Issue published August 1, 2018 Previous issue | Next issue
On the cover: Film stars: fibrin barriers obstruct bacterial invasion
In this issue of the JCI, Macrae et al. report that fibrin forms films on the air-exposed surface of blood clots that provide acute protection from pathogens following cutaneous injury. The cover image, captured by SEM, reveals a fibrin film at the air-exposed surface of a blood clot. A perforation in the film exposes the RBCs and polymerized fiber strands contained within.
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Reviews
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Abstract
Current immune checkpoint-modulating agents have demonstrated clinical efficacy in certain tumor types, particularly those with a high burden of tumor-specific neoantigens, high tumor-mutational burden, and abundant tumor-infiltrating T cells. However, these tumors often stop responding, with signs of T cells exhaustion, decreased T cell effector function, and upregulated inhibitory checkpoints. To enhance antitumor immunity and rescue exhausted T cells, newer inhibitory and stimulatory checkpoint modulators are being tested as monotherapy or in combination with approved checkpoint inhibitors. In contrast, tumors with low tumor-mutational burden, low neoantigen burden, and a paucity of T cells are immunologically “cold,” and therefore first require the addition of agents to facilitate the induction of T cells into tumors. Cold tumors also often recruit immunosuppressive cell subsets, including regulatory T cells, myeloid-derived suppressor cells, and macrophages, and secrete immunosuppressive soluble cytokines, chemokines, and metabolites. To unleash an optimal antitumor immune response, combinatorial therapeutics that combine immune checkpoints with other modalities, such as vaccines, are being developed. From current preclinical data, it appears that combinatorial strategies will provide robust and durable responses in patients with immunologically cold cancers.
Authors
Aleksandra Popovic, Elizabeth M. Jaffee, Neeha Zaidi
×Abstract
The motor neuron disease spinal muscular atrophy (SMA) is caused by recessive, loss-of-function mutations of the survival motor neuron 1 gene (SMN1). Alone, such mutations are embryonically lethal, but SMA patients retain a paralog gene, SMN2, that undergoes alternative pre-mRNA splicing, producing low levels of SMN protein. By mechanisms that are not well understood, reduced expression of the ubiquitously expressed SMN protein causes an early-onset motor neuron disease that often results in infantile or childhood mortality. Recently, striking clinical improvements have resulted from two novel treatment strategies to increase SMN protein by (a) modulating the splicing of existing SMN2 pre-mRNAs using antisense oligonucleotides, and (b) transducing motor neurons with self-complementary adeno-associated virus 9 (scAAV9) expressing exogenous SMN1 cDNA. We review the recently published clinical trial results and discuss the differing administration, tissue targeting, and potential toxicities of these two therapies. We also focus on the challenges that remain, emphasizing the many clinical and biologic questions that remain open. Answers to these questions will enable further optimization of these remarkable SMA treatments as well as provide insights that may well be useful in application of these therapeutic platforms to other diseases.
Authors
Charlotte J. Sumner, Thomas O. Crawford
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Commentaries
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Abstract
Langerhans cells (LCs) are likely among the first targets of HIV-1 infection due to their localization in mucosal tissues. In their recent work, Pena-Cruz and colleagues were able to study HIV-1 infection in vaginal epithelial DCs (VEDCs), termed CD1a+ VEDCs. They show that VEDCs are distinct from other blood- and tissue-derived DCs or LCs because they express the protein langerin but not the lectin receptor DC-SIGN, and they do not have Birbeck granules. The results from this study indicate that HIV-1 using CXCR4 replicates poorly in VEDCs but that a higher replication for HIV-1 using CCR5 strains is supported by VDECs. Furthermore, Pena-Cruz and colleagues demonstrate that VDECs can represent a viral reservoir in HIV-1–infected virologically suppressed women. As such, VDECs may represent another sanctuary of viral persistence and can be an additional obstacle to viral eradication.
Authors
Stephan Caucheteux, Vincent Piguet
×Abstract
Crescentic glomerulonephritis, a complication of severe immune glomerular injury, is the pathological correlate of rapidly progressive glomerulonephritis, mediated by both humoral and cellular effectors. In the current issue of the JCI, Chen et al. have implicated Bowman’s capsule in functionally isolating potentially immune effectors, specifically antigen-specific CD8+ T lymphocytes, from podocytes. They suggest that, in crescentic glomerulonephritis, immune-mediated glomerular endothelial injury results in inside-out injury to the glomerulus, with subsequent leukocyte migration through a weakened or ruptured Bowman’s capsule, resulting in outside-in injury. Effector T cells then recognize nephritogenic antigens presented by podocytes or other cells within the urinary space, enhancing injury and crescent formation.
Authors
A. Richard Kitching, Maliha A. Alikhan
×Abstract
The use of broad-spectrum antibiotics in empirical antimicrobial therapy is a lifesaving strategy for patients in intensive care. At the same time, antibiotics dramatically increase the risk for nosocomial infections, such as hospital‑acquired pneumonia caused by Pseudomonas aeruginosa, and other antibiotic-resistant bacteria. In this issue of the JCI, Robak and colleagues identified a mechanism by which depletion of resident gut and lung microbiota by antibiotic treatment results in secondary IgA deficiency and impaired anti–P. aeruginosa host defense. Impaired defenses could be improved by substitution of polyclonal IgA via the intranasal route in a mouse model of pneumonia. Importantly, antibiotic treatment caused lung IgA deficiency that involved reduced TLR-dependent production of a proliferation-inducing ligand (APRIL) and B cell–activating factor (BAFF) in intensive care unit patients. These patients might therefore benefit from future strategies to increase pulmonary IgA levels.
Authors
Juergen Lohmeyer, Rory E. Morty, Susanne Herold
×Abstract
Brown et al. report that two weeks of exogenous leptin administration to leptin-naive individuals with lipodystrophy resulted in increased energy expenditure and lipolysis, decreased ectopic liver fat, improved hepatic and peripheral insulin sensitivity, and attenuated dyslipidemia. Leptin withdrawal in individuals with lipodystrophy did not produce reciprocal effects on these phenotypes and resulted in significant improvements only in hepatic insulin sensitivity. This asymmetry in responses to leptin initiation and cessation is consistent with the other aspects of leptin biology that are dependent on the metabolic context in which this adipocyte-derived hormone functions.
Authors
Michael Rosenbaum, Rudolph L. Leibel
×Abstract
WHIM (warts, hypogammaglobulinemia, infections, and myelokathexis) syndrome is a genetic autoimmune disorder that results from gain-of-function mutations in the gene encoding chemokine receptor CXCR4. A previous study characterized a patient with WHIM who underwent a chromothriptic event that resulted in spontaneous deletion of the WHIM allele in a single hematopoietic stem cell and subsequent cure of the disease. In this issue of the JCI, Gao et al. extend this work and show that Cxcl4-haplosufficient bone marrow has a selective advantage for long-term engraftment in murine WHIM models. Moreover, successful engraftment occurred without prior conditioning of recipients. Together, these results have important implications for improving hematopoietic stem/progenitor cell transplant not only for patients with WHIM but also for all patients who may require the procedure.
Authors
Hal E. Broxmeyer
×Abstract
The hemostatic response to vascular injury culminates in a fibrin clot network that forms an initial barrier to blood loss and also contributes to microbial host defense. Fibrinogen is cleaved by thrombin into fibrin monomers that spontaneously polymerize into protofibrils and form the extensive fiber networks characteristic of blood clots. In this issue of the JCI, Macrae and colleagues characterize an alternative fibrin structure in which fibrinogen and fibrin assemble into a continuous 2D film at the exterior face of the fibrin clot network. Fibrin films connect to the underlying fiber network through tethering fibers and provide a protective barrier to microbial infiltration. These findings shed new light on a previously overlooked mechanism of fibrin assembly at the clot surface and provide a link between hemostasis and innate immunity.
Authors
Sean X. Gu, Steven R. Lentz
×Abstract
Resolution of inflammation is a critical process that is facilitated by specialized proresolving mediators (SPMs). In this issue, Bang et al. show that the G protein–coupled receptor GPR37 is a receptor for one such SPM, neuroprotectin D1. They also show that GPR37 activation in macrophages enhances phagocytosis, shifts cytokine release toward an antiinflammatory profile, and thereby helps to reverse inflammatory pain.
Authors
Lintao Qu, Michael J. Caterina
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Research Articles
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Abstract
PRDM16 is a transcriptional coregulator involved in translocations in acute myeloblastic leukemia (AML), myelodysplastic syndromes, and T acute lymphoblastic leukemia that is highly expressed in and required for the maintenance of hematopoietic stem cells (HSCs), and can be aberrantly expressed in AML. Prdm16 is expressed as full-length (fPrdm16) and short (sPrdm16) isoforms, the latter lacking the N-terminal PR domain. The role of both isoforms in normal and malignant hematopoiesis is unclear. We show here that fPrdm16 was critical for HSC maintenance, induced multiple genes involved in GTPase signaling, and repressed inflammation, while sPrdm16 supported B cell development biased toward marginal zone B cells and induced an inflammatory signature. In a mouse model of human MLL-AF9 leukemia, fPrdm16 extended latency, while sPrdm16 shortened latency and induced a strong inflammatory signature, including several cytokines and chemokines that are associated with myelodysplasia and with a worse prognosis in human AML. Finally, in human NPM1-mutant and in MLL-translocated AML, high expression of PRDM16, which negatively impacts outcome, was associated with inflammatory gene expression, thus corroborating the mouse data. Our observations demonstrate distinct roles for Prdm16 isoforms in normal HSCs and AML, and identify sPrdm16 as one of the drivers of prognostically adverse inflammation in leukemia.
Authors
David J. Corrigan, Larry L. Luchsinger, Mariana Justino de Almeida, Linda J. Williams, Alexandros Strikoudis, Hans-Willem Snoeck
×Abstract
TNF is an important mediator in numerous inflammatory diseases, e.g., in inflammatory bowel diseases (IBDs). In IBD, acute increases in TNF production can lead to disease flares. Glucocorticoids (GCs), which are steroids that bind and activate the glucocorticoid receptor (GR), are able to protect animals and humans against acute TNF-induced inflammatory symptoms. Mice with a poor transcriptional response of GR dimer–dependent target genes were studied in a model of TNF-induced lethal inflammation. In contrast to the GRWT/WT mice, these GRdim/dim mice displayed a substantial increase in TNF sensitivity and a lack of protection by the GC dexamethasone (DEX). Unchallenged GRdim/dim mice had a strong IFN-stimulated gene (ISG) signature, along with STAT1 upregulation and phosphorylation. This ISG signature was gut specific and, based on our studies with antibiotics, depended on the gut microbiota. GR dimers directly bound to short DNA sequences in the STAT1 promoter known as inverted repeat negative GRE (IR-nGRE) elements. Poor control of STAT1 in GRdim/dim mice led to failure to repress ISG genes, resulting in excessive necroptosis induction by TNF. Our findings support a critical interplay among gut microbiota, IFNs, necroptosis, and GR in both the basal response to acute inflammatory challenges and pharmacological intervention by GCs.
Authors
Marlies Ballegeer, Kelly Van Looveren, Steven Timmermans, Melanie Eggermont, Sofie Vandevyver, Fabien Thery, Karen Dendoncker, Jolien Souffriau, Jolien Vandewalle, Lise Van Wyngene, Riet De Rycke, Nozomi Takahashi, Peter Vandenabeele, Jan Tuckermann, Holger M. Reichardt, Francis Impens, Rudi Beyaert, Karolien De Bosscher, Roosmarijn E. Vandenbroucke, Claude Libert
×Abstract
Tumor angiogenesis occurs through regulation of genes that orchestrate endothelial sprouting and vessel maturation, including deposition of a vessel-associated extracellular matrix. CD93 is a transmembrane receptor that is upregulated in tumor vessels in many cancers, including high-grade glioma. Here, we demonstrate that CD93 regulates β1 integrin signaling and organization of fibronectin fibrillogenesis during tumor vascularization. In endothelial cells and mouse retina, CD93 was found to be expressed in endothelial filopodia and to promote filopodia formation. The CD93 localization to endothelial filopodia was stabilized by interaction with multimerin-2 (MMRN2), which inhibited its proteolytic cleavage. The CD93-MMRN2 complex was required for activation of β1 integrin, phosphorylation of focal adhesion kinase (FAK), and fibronectin fibrillogenesis in endothelial cells. Consequently, tumor vessels in gliomas implanted orthotopically in CD93-deficient mice showed diminished activation of β1 integrin and lacked organization of fibronectin into fibrillar structures. These findings demonstrate a key role of CD93 in vascular maturation and organization of the extracellular matrix in tumors, identifying it as a potential target for therapy.
Authors
Roberta Lugano, Kalyani Vemuri, Di Yu, Michael Bergqvist, Anja Smits, Magnus Essand, Staffan Johansson, Elisabetta Dejana, Anna Dimberg
×Abstract
Enterotoxigenic Escherichia coli (ETEC) infections are highly prevalent in developing countries, where clinical presentations range from asymptomatic colonization to severe cholera-like illness. The molecular basis for these varied presentations, which may involve strain-specific virulence features as well as host factors, has not been elucidated. We demonstrate that, when challenged with ETEC strain H10407, originally isolated from a case of cholera-like illness, blood group A human volunteers developed severe diarrhea more frequently than individuals from other blood groups. Interestingly, a diverse population of ETEC strains, including H10407, secrete the EtpA adhesin molecule. As many bacterial adhesins also agglutinate red blood cells, we combined the use of glycan arrays, biolayer inferometry, and noncanonical amino acid labeling with hemagglutination studies to demonstrate that EtpA is a dominant ETEC blood group A–specific lectin/hemagglutinin. Importantly, we have also shown that EtpA interacts specifically with glycans expressed on intestinal epithelial cells from blood group A individuals and that EtpA-mediated bacterial-host interactions accelerate bacterial adhesion and effective delivery of both the heat-labile and heat-stable toxins of ETEC. Collectively, these data provide additional insight into the complex molecular basis of severe ETEC diarrheal illness that may inform rational design of vaccines to protect those at highest risk.
Authors
Pardeep Kumar, F. Matthew Kuhlmann, Subhra Chakraborty, A. Louis Bourgeois, Jennifer Foulke-Abel, Brunda Tumala, Tim J. Vickers, David A. Sack, Barbara DeNearing, Clayton D. Harro, W. Shea Wright, Jeffrey C. Gildersleeve, Matthew A. Ciorba, Srikanth Santhanam, Chad K. Porter, Ramiro L. Gutierrez, Michael G. Prouty, Mark S. Riddle, Alexander Polino, Alaullah Sheikh, Mark Donowitz, James M. Fleckenstein
×Abstract
For gene therapy of gain-of-function autosomal dominant diseases, either correcting or deleting the disease allele is potentially curative. To test whether there may be an advantage of one approach over the other for WHIM (warts, hypogammaglobulinemia, infections, and myelokathexis) syndrome — a primary immunodeficiency disorder caused by gain-of-function autosomal dominant mutations in chemokine receptor CXCR4 — we performed competitive transplantation experiments using both lethally irradiated WT (Cxcr4+/+) and unconditioned WHIM (Cxcr4+/w) recipient mice. In both models, hematopoietic reconstitution was markedly superior using BM cells from donors hemizygous for Cxcr4 (Cxcr4+/o) compared with BM cells from Cxcr4+/+ donors. Remarkably, only approximately 6% Cxcr4+/o hematopoietic stem cell (HSC) chimerism after transplantation in unconditioned Cxcr4+/w recipient BM supported more than 70% long-term donor myeloid chimerism in blood and corrected myeloid cell deficiency in blood. Donor Cxcr4+/o HSCs differentiated normally and did not undergo exhaustion as late as 465 days after transplantation. Thus, disease allele deletion resulting in Cxcr4 haploinsufficiency was superior to disease allele repair in a mouse model of gene therapy for WHIM syndrome, allowing correction of leukopenia without recipient conditioning.
Authors
Ji-Liang Gao, Erin Yim, Marie Siwicki, Alexander Yang, Qian Liu, Ari Azani, Albert Owusu-Ansah, David H. McDermott, Philip M. Murphy
×Abstract
SEC24 family members are components of the coat protein complex II (COPII) machinery that interact directly with cargo or with other adapters to ensure proper sorting of secretory cargo into COPII vesicles. SEC24C is 1 of 4 mammalian SEC24 paralogs (SEC24A–D), which segregate into 2 subfamilies on the basis of sequence homology (SEC24A/SEC24B and SEC24C/SEC24D). Here, we demonstrate that postmitotic neurons, unlike professional secretory cells in other tissues, are exquisitely sensitive to loss of SEC24C. Conditional KO of Sec24c in neural progenitors during embryogenesis caused perinatal mortality and microcephaly, with activation of the unfolded protein response and apoptotic cell death of postmitotic neurons in the murine cerebral cortex. The cell-autonomous function of SEC24C in postmitotic neurons was further highlighted by the loss of cell viability caused by disrupting Sec24c expression in forebrain neurons of mice postnatally and in differentiated neurons derived from human induced pluripotent stem cells. The neuronal cell death associated with Sec24c deficiency was rescued in knockin mice expressing Sec24d in place of Sec24c. These data suggest that SEC24C is a major cargo adapter for COPII-dependent transport in postmitotic neurons in developing and adult brains and that its functions overlap at least partially with those of SEC24D in mammals.
Authors
Bo Wang, Joung Hyuck Joo, Rebecca Mount, Brett J. W. Teubner, Alison Krenzer, Amber L. Ward, Viraj P. Ichhaporia, Elizabeth J. Adams, Rami Khoriaty, Samuel T. Peters, Shondra M. Pruett-Miller, Stanislav S. Zakharenko, David Ginsburg, Mondira Kundu
×Abstract
BACKGROUND. A common germline variant in HSD3B1(1245A>C) encodes for a hyperactive 3β-hydroxysteroid dehydrogenase 1 (3βHSD1) missense that increases metabolic flux from extragonadal precursor steroids to DHT synthesis in prostate cancer. Enabling of extragonadal DHT synthesis by HSD3B1(1245C) predicts for more rapid clinical resistance to castration and sensitivity to extragonadal androgen synthesis inhibition. HSD3B1(1245C) thus appears to define a subgroup of patients who benefit from blocking extragonadal androgens. However, abiraterone, which is administered to block extragonadal androgens, is a steroidal drug that is metabolized by 3βHSD1 to multiple steroidal metabolites, including 3-keto-5α-abiraterone, which stimulates the androgen receptor. Our objective was to determine if HSD3B1(1245C) inheritance is associated with increased 3-keto-5α-abiraterone synthesis in patients. METHODS. First, we characterized the pharmacokinetics of 7 steroidal abiraterone metabolites in 15 healthy volunteers. Second, we determined the association between serum 3-keto-5α-abiraterone levels and HSD3B1 genotype in 30 patients treated with abiraterone acetate (AA) after correcting for the determined pharmacokinetics. RESULTS. Patients who inherit 0, 1, and 2 copies of HSD3B1(1245C) have a stepwise increase in normalized 3-keto-5α-abiraterone (0.04 ng/ml, 2.60 ng/ml, and 2.70 ng/ml, respectively; P = 0.002). CONCLUSION. Increased generation of 3-keto-5α-abiraterone in patients with HSD3B1(1245C) might partially negate abiraterone benefits in these patients who are otherwise more likely to benefit from CYP17A1 inhibition. FUNDING. Prostate Cancer Foundation Challenge Award, National Cancer Institute.
Authors
Mohammad Alyamani, Hamid Emamekhoo, Sunho Park, Jennifer Taylor, Nima Almassi, Sunil Upadhyay, Allison Tyler, Michael P. Berk, Bo Hu, Tae Hyun Hwang, William Douglas Figg, Cody J. Peer, Caly Chien, Vadim S. Koshkin, Prateek Mendiratta, Petros Grivas, Brian Rini, Jorge Garcia, Richard J. Auchus, Nima Sharifi
×Abstract
High-risk neuroblastoma is a devastating malignancy with very limited therapeutic options. Here, we identify withaferin A (WA) as a natural ferroptosis-inducing agent in neuroblastoma, which acts through a novel double-edged mechanism. WA dose-dependently either activates the nuclear factor–like 2 pathway through targeting of Kelch-like ECH-associated protein 1 (noncanonical ferroptosis induction) or inactivates glutathione peroxidase 4 (canonical ferroptosis induction). Noncanonical ferroptosis induction is characterized by an increase in intracellular labile Fe(II) upon excessive activation of heme oxygenase-1, which is sufficient to induce ferroptosis. This double-edged mechanism might explain the superior efficacy of WA as compared with etoposide or cisplatin in killing a heterogeneous panel of high-risk neuroblastoma cells, and in suppressing the growth and relapse rate of neuroblastoma xenografts. Nano-targeting of WA allows systemic application and suppressed tumor growth due to an enhanced accumulation at the tumor site. Collectively, our data propose a novel therapeutic strategy to efficiently kill cancer cells by ferroptosis.
Authors
Behrouz Hassannia, Bartosz Wiernicki, Irina Ingold, Feng Qu, Simon Van Herck, Yulia Y. Tyurina, Hülya Bayır, Behnaz A. Abhari, Jose Pedro Friedmann Angeli, Sze Men Choi, Eline Meul, Karen Heyninck, Ken Declerck, Chandra Sekhar Chirumamilla, Maija Lahtela-Kakkonen, Guy Van Camp, Dmitri V. Krysko, Paul G. Ekert, Simone Fulda, Bruno G. De Geest, Marcus Conrad, Valerian E. Kagan, Wim Vanden Berghe, Peter Vandenabeele, Tom Vanden Berghe
×Abstract
Hemostasis requires conversion of fibrinogen to fibrin fibers that generate a characteristic network, interact with blood cells, and initiate tissue repair. The fibrin network is porous and highly permeable, but the spatial arrangement of the external clot face is unknown. Here we show that fibrin transitioned to the blood-air interface through Langmuir film formation, producing a protective film confining clots in human and mouse models. We demonstrated that only fibrin is required for formation of the film, and that it occurred in vitro and in vivo. The fibrin film connected to the underlying clot network through tethering fibers. It was digested by plasmin, and formation of the film was prevented with surfactants. Functionally, the film retained blood cells and protected against penetration by bacterial pathogens in a murine model of dermal infection. Our data show a remarkable aspect of blood clotting in which fibrin forms a protective film covering the external surface of the clot, defending the organism against microbial invasion.
Authors
Fraser L. Macrae, Cédric Duval, Praveen Papareddy, Stephen R. Baker, Nadira Yuldasheva, Katherine J. Kearney, Helen R. McPherson, Nathan Asquith, Joke Konings, Alessandro Casini, Jay L. Degen, Simon D. Connell, Helen Philippou, Alisa S. Wolberg, Heiko Herwald, Robert A.S. Ariëns
×Abstract
Neuronatin (Nnat) is an imprinted gene implicated in human obesity and widely expressed in neuroendocrine and metabolic tissues in a hormone- and nutrient-sensitive manner. However, its molecular and cellular functions and precise role in organismal physiology remain only partly defined. Here we demonstrate that mice lacking Nnat globally or specifically in β cells display impaired glucose-stimulated insulin secretion leading to defective glucose handling under conditions of nutrient excess. In contrast, we report no evidence for any feeding or body weight phenotypes in global Nnat-null mice. At the molecular level neuronatin augments insulin signal peptide cleavage by binding to the signal peptidase complex and facilitates translocation of the nascent preprohormone. Loss of neuronatin expression in β cells therefore reduces insulin content and blunts glucose-stimulated insulin secretion. Nnat expression, in turn, is glucose-regulated. This mechanism therefore represents a novel site of nutrient-sensitive control of β cell function and whole-animal glucose homeostasis. These data also suggest a potential wider role for Nnat in the regulation of metabolism through the modulation of peptide processing events.
Authors
Steven J. Millership, Gabriela Da Silva Xavier, Agharul I. Choudhury, Sergio Bertazzo, Pauline Chabosseau, Silvia M.A. Pedroni, Elaine E. Irvine, Alex Montoya, Peter Faull, William R. Taylor, Julie Kerr-Conte, Francois Pattou, Jorge Ferrer, Mark Christian, Rosalind M. John, Mathieu Latreille, Ming Liu, Guy A. Rutter, James Scott, Dominic J. Withers
×Abstract
Clarin-1, a tetraspan-like membrane protein defective in Usher syndrome type IIIA (USH3A), is essential for hair bundle morphogenesis in auditory hair cells. We report a new synaptic role for clarin-1 in mouse auditory hair cells elucidated by characterization of Clrn1 total (Clrn1ex4–/–) and postnatal hair cell–specific conditional (Clrn1ex4fl/fl Myo15-Cre+/–) knockout mice. Clrn1ex4–/– mice were profoundly deaf, whereas Clrn1ex4fl/fl Myo15-Cre+/– mice displayed progressive increases in hearing thresholds, with, initially, normal otoacoustic emissions and hair bundle morphology. Inner hair cell (IHC) patch-clamp recordings for the 2 mutant mice revealed defective exocytosis and a disorganization of synaptic F-actin and CaV1.3 Ca2+ channels, indicative of a synaptopathy. Postsynaptic defects were also observed, with an abnormally broad distribution of AMPA receptors associated with a loss of afferent dendrites and defective electrically evoked auditory brainstem responses. Protein-protein interaction assays revealed interactions between clarin-1 and the synaptic CaV1.3 Ca2+ channel complex via the Cavβ2 auxiliary subunit and the PDZ domain–containing protein harmonin (defective in Usher syndrome type IC). Cochlear gene therapy in vivo, through adeno-associated virus–mediated Clrn1 transfer into hair cells, prevented the synaptic defects and durably improved hearing in Clrn1ex4fl/fl Myo15-Cre+/– mice. Our results identify clarin-1 as a key organizer of IHC ribbon synapses, and suggest new treatment possibilities for USH3A patients.
Authors
Didier Dulon, Samantha Papal, Pranav Patni, Matteo Cortese, Philippe F.Y. Vincent, Margot Tertrais, Alice Emptoz, Abdelaziz Tlili, Yohan Bouleau, Vincent Michel, Sedigheh Delmaghani, Alain Aghaie, Elise Pepermans, Olinda Alegria-Prevot, Omar Akil, Lawrence Lustig, Paul Avan, Saaid Safieddine, Christine Petit, Aziz El-Amraoui
×Abstract
Myocardial infarction (MI) arising from obstruction of the coronary circulation engenders massive cardiomyocyte loss and replacement by non-contractile scar tissue, leading to pathological remodeling, dysfunction, and ultimately heart failure. This is presently a global health problem for which there is no effective cure. Following MI, the innate immune system directs the phagocytosis of dead cell debris in an effort to stimulate cell repopulation and tissue renewal. In the mammalian adult heart, however, the persistent influx of immune cells, coupled with the lack of an inherent regenerative capacity, results in cardiac fibrosis. Here, we reveal that stimulation of cardiac lymphangiogenesis with VEGF-C improves clearance of the acute inflammatory response after MI by trafficking immune cells to draining mediastinal lymph nodes (MLNs) in a process dependent on lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1). Deletion of Lyve1 in mice, preventing docking and transit of leukocytes through the lymphatic endothelium, results in exacerbation of chronic inflammation and long-term deterioration of cardiac function. Our findings support targeting of the lymphatic/immune cell axis as a therapeutic paradigm to promote immune modulation and heart repair.
Authors
Joaquim Miguel Vieira, Sophie Norman, Cristina Villa del Campo, Thomas J. Cahill, Damien N. Barnette, Mala Gunadasa-Rohling, Louise A. Johnson, David R. Greaves, Carolyn A. Carr, David G. Jackson, Paul R. Riley
×Abstract
T cells play a key role in immune-mediated glomerulonephritis, but how cytotoxic T cells interact with podocytes remains unclear. To address this, we injected EGFP-specific CD8+ T cells from just EGFP death inducing (Jedi) mice into transgenic mice with podocyte-specific expression of EGFP. In healthy mice, Jedi T cells could not access EGFP+ podocytes. Conversely, when we induced nephrotoxic serum nephritis (NTSN) and injected Jedi T cells, EGFP+ podocyte transgenic mice showed enhanced proteinuria and higher blood urea levels. Morphometric analysis showed greater loss of EGFP+ podocytes, which was associated with severe crescentic and necrotizing glomerulonephritis. Notably, only glomeruli with disrupted Bowman’s capsule displayed massive CD8+ T cell infiltrates that were in direct contact with EGFP+ podocytes, causing their apoptosis. Thus, under control conditions with intact Bowman’s capsule, podocytes are not accessible to CD8+ T cells. However, breaches in Bowman’s capsule, as also noted in human crescentic glomerulonephritis, allow access of CD8+ T cells to the glomerular tuft and podocytes, resulting in their destruction. Through these mechanisms, a potentially reversible glomerulonephritis undergoes an augmentation process to a rapidly progressive glomerulonephritis, leading to end-stage kidney disease. Translating these mechanistic insights to human crescentic nephritis should direct future therapeutic interventions at blocking CD8+ T cells, especially in progressive stages of rapidly progressive glomerulonephritis.
Authors
Anqun Chen, Kyung Lee, Vivette D. D’Agati, Chengguo Wei, Jia Fu, Tian-Jun Guan, John Cijiang He, Detlef Schlondorff, Judith Agudo
×Spleen mediates a distinct hematopoietic progenitor response supporting tumor-promoting myelopoiesis
Abstract
Cancer progression is associated with alterations of intra- and extramedullary hematopoiesis to support a systemic tumor-promoting myeloid response. However, the functional specialty, mechanism, and clinical relevance of extramedullary hematopoiesis (EMH) remain unclear. Here, we showed that the heightened splenic myelopoiesis in tumor-bearing hosts was not only characterized by the accumulation of myeloid precursors, but also associated with profound functional alterations of splenic early hematopoietic stem/progenitor cells (HSPCs). With the distinct capability to produce and respond to granulocyte-macrophage CSF (GM-CSF), these splenic HSPCs were “primed” and committed to generating immunosuppressive myeloid cells. Mechanistically, the CCL2/CCR2 axis–dependent recruitment and the subsequent local education by the splenic stroma were critical for eliciting this splenic HSPC response. Selective abrogation of this splenic EMH was sufficient to synergistically enhance the therapeutic efficacy of immune checkpoint blockade. Clinically, patients with different types of solid tumors exhibited increased splenic HSPC levels associated with poor survival. These findings reveal a unique and important role of splenic hematopoiesis in tumor-associated myelopoiesis.
Authors
Chong Wu, Huiheng Ning, Mingyu Liu, Jie Lin, Shufeng Luo, Wenjie Zhu, Jing Xu, Wen-Chao Wu, Jing Liang, Chun-Kui Shao, Jiaqi Ren, Bin Wei, Jun Cui, Min-Shan Chen, Limin Zheng
×Abstract
HIV-1 acquisition occurs most commonly after sexual contact. To establish infection, HIV-1 must infect cells that support high-level replication, namely CD4+ T cells, which are absent from the outermost genital epithelium. Dendritic cells (DCs), present in mucosal epithelia, potentially facilitate HIV-1 acquisition. We show that vaginal epithelial DCs, termed CD1a+ VEDCs, are unlike other blood- and tissue-derived DCs because they express langerin but not DC-SIGN, and unlike skin-based langerin+ DC subset Langerhans cells (LCs), they do not harbor Birbeck granules. Individuals primarily acquire HIV-1 that utilizes the CCR5 receptor (termed either R5 or R5X4) during heterosexual transmission, and the mechanism for the block against variants that only use the CXCR4 receptor (classified as X4) remains unclear. We show that X4 as compared with R5 HIV-1 shows limited to no replication in CD1a+ VEDCs. This differential replication occurs after fusion, suggesting that receptor usage influences postentry steps in the virus life cycle. Furthermore, CD1a+ VEDCs isolated from HIV-1–infected virologically suppressed women harbor HIV-1 DNA. Thus, CD1a+ VEDCs are potentially infected early during heterosexual transmission and also retain virus during treatment. Understanding the interplay between HIV-1 and CD1a+ VEDCs is important for future prevention and cure strategies.
Authors
Victor Pena-Cruz, Luis M. Agosto, Hisashi Akiyama, Alex Olson, Yvetane Moreau, Jean-Robert Larrieux, Andrew Henderson, Suryaram Gummuluru, Manish Sagar
×Abstract
Podocyte malfunction occurs in autoimmune and nonautoimmune kidney disease. Calcium signaling is essential for podocyte injury, but the role of Ca2+/calmodulin–dependent kinase (CaMK) signaling in podocytes has not been fully explored. We report that podocytes from patients with lupus nephritis and focal segmental glomerulosclerosis and lupus-prone and lipopolysaccharide- or adriamycin-treated mice display increased expression of CaMK IV (CaMK4), but not CaMK2. Mechanistically, CaMK4 modulated podocyte motility by altering the expression of the GTPases Rac1 and RhoA and suppressed the expression of nephrin, synaptopodin, and actin fibers in podocytes. In addition, it phosphorylated the scaffold protein 14-3-3β, which resulted in the release and degradation of synaptopodin. Targeted delivery of a CaMK4 inhibitor to podocytes preserved their ultrastructure, averted immune complex deposition and crescent formation, and suppressed proteinuria in lupus-prone mice and proteinuria in mice exposed to lipopolysaccharide-induced podocyte injury by preserving nephrin/synaptopodin expression. In animals exposed to adriamycin, podocyte-specific delivery of a CaMK4 inhibitor prevented and reversed podocyte injury and renal disease. We conclude that CaMK4 is pivotal in immune and nonimmune podocyte injury and that its targeted cell-specific inhibition preserves podocyte structure and function and should have therapeutic value in lupus nephritis and podocytopathies, including focal segmental glomerulosclerosis.
Authors
Kayaho Maeda, Kotaro Otomo, Nobuya Yoshida, Mones S. Abu-Asab, Kunihiro Ichinose, Tomoya Nishino, Michihito Kono, Andrew Ferretti, Rhea Bhargava, Shoichi Maruyama, Sean Bickerton, Tarek M. Fahmy, Maria G. Tsokos, George C. Tsokos
×Abstract
In type 1 diabetes, cytotoxic CD8+ T cells with specificity for β cell autoantigens are found in the pancreatic islets, where they are implicated in the destruction of insulin-secreting β cells. In contrast, the disease relevance of β cell–reactive CD8+ T cells that are detectable in the circulation, and their relationship to β cell function, are not known. Here, we tracked multiple, circulating β cell–reactive CD8+ T cell subsets and measured β cell function longitudinally for 2 years, starting immediately after diagnosis of type 1 diabetes. We found that change in β cell–specific effector memory CD8+ T cells expressing CD57 was positively correlated with C-peptide change in subjects below 12 years of age. Autoreactive CD57+ effector memory CD8+ T cells bore the signature of enhanced effector function (higher expression of granzyme B, killer-specific protein of 37 kDa, and CD16, and reduced expression of CD28) compared with their CD57– counterparts, and network association modeling indicated that the dynamics of β cell–reactive CD57+ effector memory CD8+ T cell subsets were strongly linked. Thus, coordinated changes in circulating β cell–specific CD8+ T cells within the CD57+ effector memory subset calibrate to functional insulin reserve in type 1 diabetes, providing a tool for immune monitoring and a mechanism-based target for immunotherapy.
Authors
Lorraine Yeo, Alyssa Woodwyk, Sanjana Sood, Anna Lorenc, Martin Eichmann, Irma Pujol-Autonell, Rosella Melchiotti, Ania Skowera, Efthymios Fidanis, Garry M. Dolton, Katie Tungatt, Andrew K. Sewell, Susanne Heck, Alka Saxena, Craig A. Beam, Mark Peakman
×Abstract
Chromatin remodeler Brahma related gene 1 (BRG1) is silenced in approximately 10% of human pancreatic ductal adenocarcinomas (PDAs). We previously showed that BRG1 inhibits the formation of intraductal pancreatic mucinous neoplasm (IPMN) and that IPMN-derived PDA originated from ductal cells. However, the role of BRG1 in pancreatic intraepithelial neoplasia–derived (PanIN-derived) PDA that originated from acinar cells remains elusive. Here, we found that exclusive elimination of Brg1 in acinar cells of Ptf1a-CreER; KrasG12D; Brg1fl/fl mice impaired the formation of acinar-to-ductal metaplasia (ADM) and PanIN independently of p53 mutation, while PDA formation was inhibited in the presence of p53 mutation. BRG1 bound to regions of the Sox9 promoter to regulate its expression and was critical for recruitment of upstream regulators, including PDX1, to the Sox9 promoter and enhancer in acinar cells. SOX9 expression was downregulated in BRG1-depleted ADMs/PanINs. Notably, Sox9 overexpression canceled this PanIN-attenuated phenotype in KBC mice. Furthermore, Brg1 deletion in established PanIN by using a dual recombinase system resulted in regression of the lesions in mice. Finally, BRG1 expression correlated with SOX9 expression in human PDAs. In summary, BRG1 is critical for PanIN initiation and progression through positive regulation of SOX9. Thus, the BRG1/SOX9 axis is a potential target for PanIN-derived PDA.
Authors
Motoyuki Tsuda, Akihisa Fukuda, Nilotpal Roy, Yukiko Hiramatsu, Laura Leonhardt, Nobuyuki Kakiuchi, Kaja Hoyer, Satoshi Ogawa, Norihiro Goto, Kozo Ikuta, Yoshito Kimura, Yoshihide Matsumoto, Yutaka Takada, Takuto Yoshioka, Takahisa Maruno, Yuichi Yamaga, Grace E. Kim, Haruhiko Akiyama, Seishi Ogawa, Christopher V. Wright, Dieter Saur, Kyoichi Takaori, Shinji Uemoto, Matthias Hebrok, Tsutomu Chiba, Hiroshi Seno
×Abstract
Purinergic receptor-7 (P2X7R) signaling controls Th17 and Th1 generation/differentiation, while NOD-like receptor P3 (NLRP3) acts as a Th2 transcriptional factor. Here, we demonstrated the existence of a P2X7R/NLRP3 pathway in T cells that is dysregulated by a P2X7R intracellular region loss-of-function mutation, leading to NLRP3 displacement and to excessive Th17 generation due to abrogation of the NLRP3-mediated Th2 program. This ultimately resulted in poor outcomes in cardiac-transplanted patients carrying the mutant allele, who showed abnormal Th17 generation. Transient NLRP3 silencing in nonmutant T cells or overexpression in mutant T cells normalized the Th profile. Interestingly, IL-17 blockade reduced Th17 skewing of human T cells in vitro and abrogated the severe allograft vasculopathy and abnormal Th17 generation observed in preclinical models in which P2X7R was genetically deleted. This P2X7R intracellular region mutation thus impaired the modulatory effects of P2X7R on NLRP3 expression and function in T cells and led to NLRP3 dysregulation and Th17 skewing, delineating a high-risk group of cardiac-transplanted patients who may benefit from personalized therapy.
Authors
Francesca D’Addio, Andrea Vergani, Luciano Potena, Anna Maestroni, Vera Usuelli, Moufida Ben Nasr, Roberto Bassi, Sara Tezza, Sergio Dellepiane, Basset El Essawy, Maria Iascone, Attilio Iacovoni, Laura Borgese, Kaifeng Liu, Gary Visner, Sirano Dhe-Paganon, Domenico Corradi, Reza Abdi, Randall C. Starling, Franco Folli, Gian Vincenzo Zuccotti, Mohamed H. Sayegh, Peter S. Heeger, Anil Chandraker, Francesco Grigioni, Paolo Fiorina
×Abstract
BACKGROUND. Recombinant leptin (metreleptin) ameliorates hyperphagia and metabolic abnormalities in leptin-deficient humans with lipodystrophy. We aimed to determine whether metreleptin improves glucose and lipid metabolism in humans when food intake is held constant. METHODS. Patients with lipodystrophy were hospitalized for 19 days, with food intake held constant by a controlled diet in an inpatient metabolic ward. In a nonrandomized, crossover design, patients previously treated with metreleptin (n = 8) were continued on metreleptin for 5 days and then taken off metreleptin for the next 14 days (withdrawal cohort). This order was reversed in metreleptin-naive patients (n = 14), who were reevaluated after 6 months of metreleptin treatment on an ad libitum diet (initiation cohort). Outcome measurements included insulin sensitivity by hyperinsulinemic-euglycemic clamp, fasting glucose and triglyceride levels, lipolysis measured using isotopic tracers, and liver fat by magnetic resonance spectroscopy. RESULTS. With food intake constant, peripheral insulin sensitivity decreased by 41% after stopping metreleptin for 14 days (withdrawal cohort) and increased by 32% after treatment with metreleptin for 14 days (initiation cohort). In the initiation cohort only, metreleptin decreased fasting glucose by 11% and triglycerides by 41% and increased hepatic insulin sensitivity. Liver fat decreased from 21.8% to 18.7%. In the initiation cohort, changes in lipolysis were not independent of food intake, but after 6 months of metreleptin treatment on an ad libitum diet, lipolysis decreased by 30% (palmitate turnover) to 35% (glycerol turnover). CONCLUSION. Using lipodystrophy as a human model of leptin deficiency and replacement, we show that metreleptin improves insulin sensitivity and decreases hepatic and circulating triglycerides and that these improvements are independent of its effects on food intake. TRIAL REGISTRATION. ClinicalTrials.gov NCT01778556 FUNDING. This research was supported by the intramural research program of the NIDDK.
Authors
Rebecca J. Brown, Areli Valencia, Megan Startzell, Elaine Cochran, Peter J. Walter, H. Martin Garraffo, Hongyi Cai, Ahmed M. Gharib, Ronald Ouwerkerk, Amber B. Courville, Shanna Bernstein, Robert J. Brychta, Kong Y. Chen, Mary Walter, Sungyoung Auh, Phillip Gorden
×Abstract
A homozygous truncating frameshift mutation in CEP57 (CEP57T/T) has been identified in a subset of mosaic-variegated aneuploidy (MVA) patients; however, the physiological roles of the centrosome-associated protein CEP57 that contribute to disease are unknown. To investigate these, we have generated a mouse model mimicking this disease mutation. Cep57T/T mice died within 24 hours after birth with short, curly tails and severely impaired vertebral ossification. Osteoblasts in lumbosacral vertebrae of Cep57T/T mice were deficient for Fgf2, a Cep57 binding partner implicated in diverse biological processes, including bone formation. Furthermore, a broad spectrum of tissues of Cep57T/T mice had severe aneuploidy at birth, consistent with the MVA patient phenotype. Cep57T/T mouse embryonic fibroblasts and patient-derived skin fibroblasts failed to undergo centrosome maturation in G2 phase, causing premature centriole disjunction, centrosome amplification, aberrant spindle formation, and high rates of chromosome missegregation. Mice heterozygous for the truncating frameshift mutation or a Cep57-null allele were overtly indistinguishable from WT mice despite reduced Cep57 protein levels, yet prone to aneuploidization and cancer, with tumors lacking evidence for loss of heterozygosity. This study identifies Cep57 as a haploinsufficient tumor suppressor with biologically diverse roles in centrosome maturation and Fgf2-mediated bone formation.
Authors
Khaled Aziz, Cynthia J. Sieben, Karthik B. Jeganathan, Masakazu Hamada, Brian A. Davies, Raul O. Fierro Velasco, Nazneen Rahman, David J. Katzmann, Jan M. van Deursen
×Abstract
Broad-spectrum antibiotics are widely used with patients in intensive care units (ICUs), many of whom develop hospital-acquired infections with Pseudomonas aeruginosa. Although preceding antimicrobial therapy is known as a major risk factor for P. aeruginosa–induced pneumonia, the underlying mechanisms remain incompletely understood. Here we demonstrate that depletion of the resident microbiota by broad-spectrum antibiotic treatment inhibited TLR-dependent production of a proliferation-inducing ligand (APRIL), resulting in a secondary IgA deficiency in the lung in mice and human ICU patients. Microbiota-dependent local IgA contributed to early antibacterial defense against P. aeruginosa. Consequently, P. aeruginosa–binding IgA purified from lamina propria culture or IgA hybridomas enhanced resistance of antibiotic-treated mice to P. aeruginosa infection after transnasal substitute. Our study provides a mechanistic explanation for the well-documented risk of P. aeruginosa infection following antimicrobial therapy, and we propose local administration of IgA as a novel prophylactic strategy.
Authors
Oliver H. Robak, Markus M. Heimesaat, Andrey A. Kruglov, Sandra Prepens, Justus Ninnemann, Birgitt Gutbier, Katrin Reppe, Hubertus Hochrein, Mark Suter, Carsten J. Kirschning, Veena Marathe, Jan Buer, Mathias W. Hornef, Markus Schnare, Pascal Schneider, Martin Witzenrath, Stefan Bereswill, Ulrich Steinhoff, Norbert Suttorp, Leif E. Sander, Catherine Chaput, Bastian Opitz
×Abstract
The biological activity of 24R,25-dihydroxyvitamin D3 [24R,25(OH)2D3] remains controversial, but it has been suggested that it contributes to fracture healing. Cyp24a1–/– mice, synthesizing no 24R,25(OH)2D3, show suboptimal endochondral ossification during fracture repair, with smaller callus and reduced stiffness. These defects were corrected by 24R,25(OH)2D3 treatment, but not by 1,25-dihydroxyvitamin D3. Microarrays with Cyp24a1–/– callus mRNA identified FAM57B2 as a mediator of the 24R,25(OH)2D3 effect. FAM57B2 produced lactosylceramide (LacCer) upon specific binding of 24R,25(OH)2D3. Fam57b inactivation in chondrocytes (Col2-Cre Fam57bfl/fl) phenocopied the callus formation defect of Cyp24a1–/– mice. LacCer or 24R,25(OH)2D3 injections restored callus volume, stiffness, and mineralized cartilage area in Cyp24a1-null mice, but only LacCer rescued Col2-Cre Fam57bfl/fl mice. Gene expression in callus tissue suggested that the 24R,25(OH)2D3/FAM57B2 cascade affects cartilage maturation. We describe a previously unrecognized pathway influencing endochondral ossification during bone repair through LacCer production upon binding of 24R,25(OH)2D3 to FAM57B2. Our results identify potential new approaches to ameliorate fracture healing.
Authors
Corine Martineau, Roy Pascal Naja, Abdallah Husseini, Bachar Hamade, Martin Kaufmann, Omar Akhouayri, Alice Arabian, Glenville Jones, René St-Arnaud
×Abstract
Mutations in superoxide dismutase 1 (SOD1) are responsible for 20% of familial ALS. Given the gain of toxic function in this dominantly inherited disease, lowering SOD1 mRNA and protein is predicted to provide therapeutic benefit. An early generation antisense oligonucleotide (ASO) targeting SOD1 was identified and tested in a phase I human clinical trial, based on modest protection in animal models of SOD1 ALS. Although the clinical trial provided encouraging safety data, the drug was not advanced because there was progress in designing other, more potent ASOs for CNS application. We have developed next-generation SOD1 ASOs that more potently reduce SOD1 mRNA and protein and extend survival by more than 50 days in SOD1G93A rats and by almost 40 days in SOD1G93A mice. We demonstrated that the initial loss of compound muscle action potential in SOD1G93A mice is reversed after a single dose of SOD1 ASO. Furthermore, increases in serum phospho-neurofilament heavy chain levels, a promising biomarker for ALS, are stopped by SOD1 ASO therapy. These results define a highly potent, new SOD1 ASO ready for human clinical trial and suggest that at least some components of muscle response can be reversed by therapy.
Authors
Alex McCampbell, Tracy Cole, Amy J. Wegener, Giulio S. Tomassy, Amy Setnicka, Brandon J. Farley, Kathleen M. Schoch, Mariah L. Hoye, Mark Shabsovich, Linhong Sun, Yi Luo, Mingdi Zhang, Nicole Comfort, Bin Wang, Jessica Amacker, Sai Thankamony, David W. Salzman, Merit Cudkowicz, Danielle L. Graham, C. Frank Bennett, Holly B. Kordasiewicz, Eric E. Swayze, Timothy M. Miller
×Abstract
The mechanisms of pain induction by inflammation have been extensively studied. However, the mechanisms of pain resolution are not fully understood. Here, we report that GPR37, expressed by macrophages (MΦs) but not microglia, contributes to the resolution of inflammatory pain. Neuroprotectin D1 (NPD1) and prosaptide TX14 increase intracellular Ca2+ (iCa2+) levels in GPR37-transfected HEK293 cells. NPD1 and TX14 also bind to GPR37 and cause GPR37-dependent iCa2+ increases in peritoneal MΦs. Activation of GPR37 by NPD1 and TX14 triggers MΦ phagocytosis of zymosan particles via calcium signaling. Hind paw injection of pH-sensitive zymosan particles not only induces inflammatory pain and infiltration of neutrophils and MΦs, but also causes GPR37 upregulation in MΦs, phagocytosis of zymosan particles and neutrophils by MΦs in inflamed paws, and resolution of inflammatory pain in WT mice. Mice lacking Gpr37 display deficits in MΦ phagocytic activity and delayed resolution of inflammatory pain. Gpr37-deficient MΦs also show dysregulations of proinflammatory and antiinflammatory cytokines. MΦ depletion delays the resolution of inflammatory pain. Adoptive transfer of WT but not Gpr37-deficient MΦs promotes the resolution of inflammatory pain. Our findings reveal a previously unrecognized role of GPR37 in regulating MΦ phagocytosis and inflammatory pain resolution.
Authors
Sangsu Bang, Ya-Kai Xie, Zhi-Jun Zhang, Zilong Wang, Zhen-Zhong Xu, Ru-Rong Ji
×Abstract
T cells must migrate in order to encounter antigen-presenting cells (APCs) and to execute their varied functions in immune defense and inflammation. ATP release and autocrine signaling through purinergic receptors contribute to T cell activation at the immune synapse that T cells form with APCs. Here, we show that T cells also require ATP release and purinergic signaling for their migration to APCs. We found that the chemokine stromal-derived factor-1α (SDF-1α) triggered mitochondrial ATP production, rapid bursts of ATP release, and increased migration of primary human CD4+ T cells. This process depended on pannexin-1 ATP release channels and autocrine stimulation of P2X4 receptors. SDF-1α stimulation caused localized accumulation of mitochondria with P2X4 receptors near the front of cells, resulting in a feed-forward signaling mechanism that promotes cellular Ca2+ influx and sustains mitochondrial ATP synthesis at levels needed for pseudopod protrusion, T cell polarization, and cell migration. Inhibition of P2X4 receptors blocked the activation and migration of T cells in vitro. In a mouse lung transplant model, P2X4 receptor antagonist treatment prevented the recruitment of T cells into allograft tissue and the rejection of lung transplants. Our findings suggest that P2X4 receptors are therapeutic targets for immunomodulation in transplantation and inflammatory diseases.
Authors
Carola Ledderose, Kaifeng Liu, Yutaka Kondo, Christian J. Slubowski, Thomas Dertnig, Sara Denicoló, Mona Arbab, Johannes Hubner, Kirstin Konrad, Mahtab Fakhari, James A. Lederer, Simon C. Robson, Gary A. Visner, Wolfgang G. Junger
×Abstract
Autosomal dominant hyper IgE syndrome (AD-HIES), or Job’s syndrome, is a primary immune deficiency caused by dominant-negative mutations in STAT3. Recurrent Staphylococcus aureus skin abscesses are a defining feature of this syndrome. A widely held hypothesis that defects in peripheral Th17 differentiation confer this susceptibility has never been directly evaluated. To assess the cutaneous immune response in AD-HIES, we induced suction blisters in healthy volunteers (HVs) and patients with AD-HIES and then challenged the wound with lethally irradiated bacteria. We show that cutaneous production of IL-17A and IL-17F was normal in patients with AD-HIES. Overproduction of TNF-α differentiated the responses in AD-HIES from HVs. This was associated with reduced IL-10 family signaling in blister-infiltrating cells and defective epithelial cell function. Mouse models of AD-HIES recapitulated these aberrant epithelial responses to S. aureus and involved defective epithelial-to-mesenchymal transition (EMT) rather than a failure of bacterial killing. Defective responses in mouse models of AD-HIES and primary keratinocyte cultures from patients with AD-HIES could be reversed by TNF-α blockade and by drugs with reported modulatory effects on EMT. Our results identify these as potential therapeutic approaches in patients with AD-HIES suffering S. aureus infections.
Authors
Ian A. Myles, Erik D. Anderson, Noah J. Earland, Kol A. Zarember, Inka Sastalla, Kelli W. Williams, Portia Gough, Ian N. Moore, Sundar Ganesan, Cedar J. Fowler, Arian Laurence, Mary Garofalo, Douglas B. Kuhns, Mark D. Kieh, Arhum Saleem, Pamela A. Welch, Dirk A. Darnell, John I. Gallin, Alexandra F. Freeman, Steven M. Holland, Sandip K. Datta
×Abstract
While the genomic binding of MYC protein correlates with active epigenetic marks on chromatin, it remains largely unclear how major epigenetic mechanisms functionally impact the tumorigenic potential of MYC. Here, we show that, compared with the catalytic subunits, the core subunits, including DPY30, of the major H3K4 methyltransferase complexes were frequently amplified in human cancers and selectively upregulated in Burkitt lymphoma. We show that DPY30 promoted the expression of endogenous MYC and was also functionally important for efficient binding of MYC to its genomic targets by regulating chromatin accessibility. Dpy30 heterozygosity did not affect normal animal physiology including lifespan, but significantly suppressed Myc-driven lymphomagenesis, as cells failed to combat oncogene-triggered apoptosis as a result of insufficient epigenetic modulation and expression of a subset of antiapoptotic genes. Dpy30 reduction also greatly impeded MYC-dependent cellular transformation, without affecting normal cell growth. These results suggest that MYC hijacks a major epigenetic pathway — H3K4 methylation — to facilitate its molecular activity in target binding and to coordinate its oncogenic program for efficient tumorigenesis, meanwhile creating “epigenetic vulnerability.” DPY30 and the H3K4 methylation pathway are thus potential epigenetic targets for treating certain MYC-driven cancers.
Authors
Zhenhua Yang, Kushani Shah, Theodore Busby, Keith Giles, Alireza Khodadadi-Jamayran, Wei Li, Hao Jiang
×Abstract
The tumor-suppressive role of trefoil factor family (TFF) members in gastric carcinogenesis has been suggested, but their significance and mechanisms in other digestive diseases remain elusive. To clarify the role of TFF1 in pancreatic carcinogenesis, we performed IHC on human samples, transfected siRNA against TFF1 into pancreatic cancer cell lines, and employed mouse models in which PanIN development and loss of TFF1 occur simultaneously. In human samples, the expression of TFF1 was specifically observed in pancreatic intraepithelial neoplasm (PanIN), but was frequently lost in the invasive component of pancreatic ductal adenocarcinoma (PDAC). When the expression of TFF1 was suppressed in vitro, pancreatic cancer cell lines showed enhanced invasive ability and features of epithelial-mesenchymal transition (EMT), including upregulated Snail expression. TFF1 expression was also observed in PanIN lesions of Pdx-1 Cre; LSL-KRASG12D (KC) mice, a model of pancreatic cancer, and loss of TFF1 in these mice resulted in the expansion of PanIN lesions, an EMT phenotype in PanIN cells, and an accumulation of cancer-associated fibroblasts (CAFs), eventually resulting in the development of invasive adenocarcinoma. This study indicates that the acquisition of TFF1 expression is an early event in pancreatic carcinogenesis and that TFF1 might act as a tumor suppressor to prevent EMT and the invasive transformation of PanIN.
Authors
Junpei Yamaguchi, Yukihiro Yokoyama, Toshio Kokuryo, Tomoki Ebata, Atsushi Enomoto, Masato Nagino
×Abstract
Skeletal muscle has emerged as a critical, disease-relevant target tissue in spinal and bulbar muscular atrophy, a degenerative disorder of the neuromuscular system caused by a CAG/polyglutamine (polyQ) expansion in the androgen receptor (AR) gene. Here, we used RNA-sequencing (RNA-Seq) to identify pathways that are disrupted in diseased muscle using AR113Q knockin mice. This analysis unexpectedly identified substantially diminished expression of numerous ubiquitin/proteasome pathway genes in AR113Q muscle, encoding approximately 30% of proteasome subunits and 20% of E2 ubiquitin conjugases. These changes were age, hormone, and glutamine length dependent and arose due to a toxic gain of function conferred by the mutation. Moreover, altered gene expression was associated with decreased levels of the proteasome transcription factor NRF1 and its activator DDI2 and resulted in diminished proteasome activity. Ubiquitinated ADRM1 was detected in AR113Q muscle, indicating the occurrence of stalled proteasomes in mutant mice. Finally, diminished expression of Drosophila orthologues of NRF1 or ADRM1 promoted the accumulation of polyQ AR protein and increased toxicity. Collectively, these data indicate that AR113Q muscle develops progressive proteasome dysfunction that leads to the impairment of quality control and the accumulation of polyQ AR protein, key features that contribute to the age-dependent onset and progression of this disorder.
Authors
Samir R. Nath, Zhigang Yu, Theresa A. Gipson, Gregory B. Marsh, Eriko Yoshidome, Diane M. Robins, Sokol V. Todi, David E. Housman, Andrew P. Lieberman
×Abstract
Ciliopathies are clinically overlapping genetic disorders involving structural and functional abnormalities of cilia. Currently, there are no small-molecule drugs available to treat ciliary defects in ciliopathies. Our phenotype-based screen identified the flavonoid eupatilin and its analogs as lead compounds for developing ciliopathy medication. CEP290, a gene mutated in several ciliopathies, encodes a protein that forms a complex with NPHP5 to support the function of the ciliary transition zone. Eupatilin relieved ciliogenesis and ciliary receptor delivery defects resulting from deletion of CEP290. In rd16 mice harboring a blinding Cep290 in-frame deletion, eupatilin treatment improved both opsin transport to the photoreceptor outer segment and electrophysiological responses of the retina to light stimulation. The rescue effect was due to eupatilin-mediated inhibition of calmodulin binding to NPHP5, which promoted NPHP5 recruitment to the ciliary base. Our results suggest that deficiency of a ciliopathy protein could be mitigated by small-molecule compounds that target other ciliary components that interact with the ciliopathy protein.
Authors
Yong Joon Kim, Sungsoo Kim, Yooju Jung, Eunji Jung, Ho Jeong Kwon, Joon Kim
Copyright © 2025 American Society for Clinical Investigation
ISSN: 0021-9738 (print), 1558-8238 (online)