Human C-terminal CUBN variants associate with chronic proteinuria and normal renal function

• Text
• PDF

Abstract

Background: Proteinuria is considered as an unfavorable clinical condition that accelerates renal and cardiovascular disease. However, it is not clear if all forms of proteinuria are damaging. Mutations in CUBN cause Imerslund-Gräsbeck syndrome (IGS) featured by intestinal malabsorption of vitamin B12 and in some cases proteinuria. CUBN encodes for cubilin, an intestinal and proximal tubular uptake receptor containing 27 CUB domains for ligand binding. Methods: We used next-generation sequencing for renal disease genes to genotype cohorts of patients with suspected hereditary renal disease and chronic proteinuria. CUBN variants were analyzed using bioinformatics, structural modeling and epidemiological methods. Results: We identified 39 patients, in whom biallelic pathogenic variants in the CUBN gene are associated with chronic isolated proteinuria with childhood onset. Since the proteinuria displayed a high proportion of albuminuria, glomerular diseases such as steroid-resistant nephrotic syndrome or Alport syndrome were often the primary clinical diagnosis, motivating renal biopsies and proteinuria-lowering treatments. Yet, renal function was normal in all cases. By contrast, we did not find any biallelic pathogenic CUBN variants in patients with reduced renal function or focal segmental glomerulosclerosis. Unlike the more N-terminal IGS mutations, 37 out of the 41 proteinuria-associated CUBN variants led to modifications or truncations after the vitamin B12-binding domain. Finally, we show that four C-terminal CUBN variants are associated with albuminuria and moderately increased GFR in meta-analyses of large population-based cohorts. Conclusions: Collectively, our data suggest an important role for the C-terminal half of cubilin in renal albumin reabsorption. Albuminuria due to reduced cubilin function could be an unexpectedly common benign condition in humans that may not require any proteinuria-lowering treatment or renal biopsies.

Authors

Mathilda Bedin, Olivia Boyer, Aude Servais, Yong Li, Laure Villoing-Gaudé, Marie-Josephe Tête, Alexandra Cambier, Julien Hogan, Veronique Baudouin, Saoussen Krid, Albert Bensman, Florie Lammens, Ferielle Louillet, Bruno Ranchin, Cecile Vigneau, Iseline Bouteau, Corinne Isnard-Bagnis, Christoph J. Mache, Tobias Schäfer, Lars Pape, Markus Gödel, Tobias B. Huber, Marcus Benz, Günter Klaus, Matthias Hansen, Kay Latta, Olivier Gribouval, Vincent Morinière, Carole Tournant, Maik Grohmann, Elisa Kuhn, Timo Wagner, Christine Bole-Feysot, Fabienne Jabot-Hanin, Patrick Nitschké, Tarunveer S. Ahluwalia, Anna Köttgen, Christian Brix Folsted Andersen, Carsten Bergmann, Corinne Antignac, Matias Simons

Chronic myelogenous leukemia stem cells require cell-autonomous pleiotrophin signaling

• Text
• PDF

Abstract

Tyrosine kinase inhibitors (TKIs) induce molecular remission in the majority of patients with chronic myelogenous leukemia (CML), but persistence of CML stem cells hinders cure and necessitates indefinite TKI therapy. We report that CML stem cells upregulate expression of pleiotrophin (PTN) and require cell-autonomous PTN signaling for CML pathogenesis in BCR/ABL+ mice. Constitutive PTN deletion substantially reduced the numbers of CML stem cells capable of initiating CML in vivo. Hematopoietic cell–specific deletion of PTN suppressed CML development in BCR/ABL+ mice, suggesting that cell-autonomous PTN signaling was necessary for CML disease evolution. Mechanistically, PTN promoted CML stem cell survival and TKI resistance via induction of Jun and the unfolded protein response. Human CML cells were also dependent on cell-autonomous PTN signaling and anti–PTN antibody suppressed human CML colony formation and CML repopulation in vivo. Our results suggest that targeted inhibition of PTN has therapeutic potential to eradicate CML stem cells.

Authors

Heather A. Himburg, Martina Roos, Tiancheng Fang, Yurun Zhang, Christina M. Termini, Lauren Schlussel, Mindy M. Kim, Amara Pang, Jenny Kan, Liman Zhao, Hyung Suh, Joshua P. Sasine, Gopal Sapparapu, Peter M. Bowers, Gary Schiller, John P. Chute

Epidermal hepcidin is required for neutrophil response to bacterial infection

• Text
• PDF

Abstract

Novel approaches for adjunctive therapy are urgently needed for infections complicated by antibiotic-resistant pathogens and for patients with compromised immunity. Necrotizing fasciitis (NF) is a destructive skin and soft tissue infection. Despite treatment with systemic antibiotics and radical debridement of necrotic tissue, lethality remains high. The key iron regulatory hormone hepcidin was originally identified as a cationic antimicrobial peptide (AMP), but its putative expression and role in the skin, a major site of AMP production, has never been investigated. We report here that hepcidin production is induced in the skin of patients with Group A Streptococcal (GAS) NF. In a GAS-induced NF model, mice lacking hepcidin in keratinocytes failed to restrict systemic spread of infection from an initial tissue focus. Unexpectedly, this effect was due its ability to promote production of the CXCL1 chemokine by keratinocytes resulting in neutrophil recruitment. Unlike CXCL1, hepcidin is resistant to degradation by major GAS proteases and could therefore serve as a reservoir to maintain steady state levels of CXCL1 in infected tissue. Finally, injection of synthetic hepcidin at the site of infection can limit or completely prevent systemic spread of GAS infection suggesting that hepcidin agonists could have a therapeutic role in NF.

Authors

Mariangela Malerba, Sabine Louis, Sylvain Cuvellier, Srikanth Mairpady Shambat, Camille Hua, Camille Gomart, Agnès Fouet, Nicolas Ortonne, Jean-Winoc Decousser, Annelies S. Zinkernagel, Jacques R.R. Mathieu, Carole Peyssonnaux

Relief of tumor hypoxia unleashes the tumoricidal potential of neutrophils

• Text
• PDF

Abstract

Polymorphonuclear neutrophils (PMNs) are increasingly recognized to influence solid tumor development, but why their effects are so context-dependent and even frequently divergent remains poorly understood. Using an autochthonous mouse model of uterine cancer and the administration of respiratory hyperoxia as a means to improve tumor oxygenation, we provide in vivo evidence that hypoxia is a potent determinant of tumor-associated PMN phenotypes and direct PMN-tumor cell interactions. Upon relief of tumor hypoxia, PMNs were recruited less intensely to the tumor-bearing uterus but the recruited cells much more effectively killed tumor cells, an activity our data moreover suggested was mediated via their production of NADPH oxidase-derived reactive oxygen species and MMP-9. Simultaneously, their ability to promote tumor cell proliferation, which appeared mediated via their production of neutrophil elastase, was rendered less effective. Relieving tumor hypoxia thus greatly improved net PMN-dependent tumor control, leading to a massive reduction in tumor burden. Remarkably, this outcome was T cell-independent. Together, these findings identify key hypoxia-regulated molecular mechanisms through which PMNs directly induce tumor cell death and proliferation in vivo and suggest that the contrasting properties of PMNs in different tumor settings may in part reflect the effects of hypoxia on direct PMN-tumor cell interactions.

Authors

Karim Mahiddine, Adam Blaisdell, Stephany Ma, Amandine Créquer-Grandhomme, Clifford A. Lowell, Adrian Erlebacher

Exosomal long noncoding RNA LNMAT2 promotes lymphatic metastasis in bladder cancer

• Text
• PDF

Abstract

Patients with bladder cancer (BCa) with clinical lymph node (LN) metastasis have extremely poor prognosis. VEGF-C has been demonstrated to play vital roles in LN metastasis in BCa. However, approximately 20% of BCa with LN metastasis exhibits low VEGF-C expression, suggesting a VEGF-C-independent mechanism for LN metastasis of BCa. Herein, we demonstrated that BCa cell-secreted exosomes-mediated lymphangiogenesis promoted LN metastasis in BCa, which was in a VEGF-C-independent manner. We identified an exosomal long noncoding RNA (lncRNA), termed lymph node metastasis-associated transcript 2 (LNMAT2), stimulated HLEC tube formation and migration in vitro and enhanced tumor lymphangiogenesis and LN metastasis in vivo. Mechanistically, LNMAT2 was loaded to BCa cell-secreted exosomes by directly interacting with heterogeneous nuclear ribonucleoprotein A2B1 (hnRNPA2B1). Subsequently, exosomal LNMAT2 was internalized by HLECs and epigenetically upregulated prospero homeobox 1 (PROX1) expression by recruitment of hnRNPA2B1 and increasing the H3K4 trimethylation level in the PROX1 promoter, ultimately resulting in lymphangiogenesis and lymphatic metastasis. Therefore, our findings highlight a VEGF-C-independent mechanism of exosomal lncRNA-mediated LN metastasis and identify LNMAT2 as a therapeutic target for LN metastasis in BCa.

Authors

Changhao Chen, Yuming Luo, Wang He, Yue Zhao, Yao Kong, Hongwei Liu, Guangzheng Zhong, Yuting Li, Jun Li, Jian Huang, Rufu Chen, Tianxin Lin

Selective DNA-PKcs inhibition extends the therapeutic index of localized radiotherapy and chemotherapy

• Text
• PDF

Abstract

Potentiating radiotherapy and chemotherapy by inhibiting DNA damage repair is proposed as a therapeutic strategy to improve outcomes for patients with solid tumors. However, this approach risks enhancing normal tissue toxicity as much as tumor toxicity, thereby limiting its translational impact. Using NU5455, a newly-identified highly-selective oral inhibitor of DNA-dependent protein kinase catalytic subunit (DNA-PKcs) activity, we found that it was indeed possible to preferentially augment the effect of targeted-radiotherapy on human orthotopic lung tumors without influencing acute DNA-damage or a late radiation-induced toxicity (fibrosis) to normal mouse lung. Furthermore, while NU5455 administration increased both the efficacy and toxicity of a parenterally-administered topoisomerase inhibitor, it enhanced the activity of doxorubicin released locally in liver tumor xenografts without inducing any adverse effect. This strategy is particularly relevant to hepatocellular cancer which is treated clinically with localized drug-eluting beads and for which DNA-PKcs activity is reported to confer resistance to treatment. We conclude that transient pharmacological inhibition of DNA-PKcs activity is effective and tolerable when combined with localized DNA-damaging therapies and thus has promising clinical potential.

Authors

Catherine E. Willoughby, Yanyan Jiang, Huw D. Thomas, Elaine Willmore, Suzanne Kyle, Anita Wittner, Nicole Phillips, Yan Zhao, Susan J. Tudhope, Lisa Prendergast, Gesa Junge, Luiza Madia Lourenco, M. Raymond V. Finlay, Paul Turner, Joanne M. Munck, Roger J. Griffin, Tommy Rennison, James Pickles, Celine Cano, David R. Newell, Helen L. Reeves, Anderson J. Ryan, Stephen R. Wedge

Increased expression of anion transporter SLC26A9 delays diabetes onset in cystic fibrosis

• Text
• PDF

Abstract

Diabetes is a common complication of cystic fibrosis (CF) that affects approximately 20% of adolescents and 40% to 50% of adults with CF. The age-at-onset of CF-related diabetes (marked by clinical diagnosis and treatment initiation) is an important measure of the disease process. DNA variants associated with age-at-onset of CFRD reside in and near SLC26A9. Deep sequencing of the SLC26A9 gene in 762 individuals with CF revealed that two common DNA haplotypes formed by the risk variants account for the association with diabetes (high risk, P-value: 4.34E-3; low risk, P-value: 1.14E-3). Single-cell RNA (scRNA) sequencing indicated that SLC26A9 is predominantly expressed in pancreatic ductal cells, and frequently co-expressed with CFTR along with transcription factors that have binding sites 5′ of SLC26A9. These findings replicated upon re-analysis of scRNA data from 4 independent studies. DNA fragments derived from the 5′ region of SLC26A9 bearing variants from the low risk haplotype generated 12% to 20% higher levels of expression in PANC-1 and CFPAC-1 cells compared to the high risk haplotype (P-values: 2.00E-3 to 5.15E-9). Taken together, our findings indicate that an increase in SLC26A9 expression in ductal cells of the pancreas delays the age-at-onset of diabetes, thereby suggesting a CFTR-agnostic treatment for a major complication of CF.

Authors

Anh-Thu N. Lam, Melis A. Aksit, Briana Vecchio-Pagan, Celeste A. Shelton, Derek L. Osorio, Arianna F. Anzmann, Loyal A. Goff, David C. Whitcomb, Scott M. Blackman, Garry R. Cutting

Myelin-specific CD8 T cells exacerbate brain inflammation in CNS autoimmunity

• Text
• PDF

Abstract

Multiple sclerosis (MS) is an inflammatory, demyelinating disease of the CNS. Although CD4 T cells are implicated in MS pathogenesis and have been the main focus of MS research using the animal model experimental autoimmune encephalomyelitis (EAE), substantial evidence from patients with MS points to a role for CD8 T cells in disease pathogenesis. We previously showed that an MHC class I-restricted epitope of myelin basic protein (MBP) is presented in the CNS during CD4 T cell-initiated EAE. Here, we investigated whether naïve MBP-specific CD8 T cells recruited to the CNS during CD4 T cell-initiated EAE engaged in determinant-spreading and influenced disease. We found that the MBP-specific CD8 T cells exacerbated brain but not spinal cord inflammation. We show that a higher frequency of monocytes and monocyte-derived cells presented the MHC class I-restricted MBP ligand in the brain compared to the spinal cord. Infiltration of MBP-specific CD8 T cells enhanced ROS production in the brain only in these cell-types and only when the MBP-specific CD8 T cells expressed Fas ligand (FasL). These results suggest that myelin-specific CD8 T cells may contribute to disease pathogenesis via a FasL-dependent mechanism that preferentially promotes lesion formation in the brain.

Authors

Catriona A. Wagner, Pamela J. Roqué, Trevor R. Mileur, Denny Liggitt, Joan M. Goverman

Low- and high-thermogenic brown adipocyte subpopulations coexist in murine adipose tissue

• Text
• PDF

Abstract

Brown adipose tissue (BAT), as the main site of adaptive thermogenesis, exerts beneficial metabolic effects on obesity and insulin resistance. BAT has been previously assumed to contain a homogeneous population of brown adipocytes. Utilizing multiple mouse models capable of genetically labeling different cellular populations, as well as single-cell RNA sequencing, and 3D tissue profiling, we discovered a new brown adipocyte subpopulation with low thermogenic activity co-existing with the classical high thermogenic brown adipocytes within the BAT. These low thermogenic brown adipocytes had significantly lower Ucp1 and Adipoq expression, larger lipid droplets, and lower mitochondrial content. Functional analyses showed that the low thermogenic brown adipocytes have significant lower basal mitochondrial respiration, and they are specialized in fatty acid uptake. Upon changes in environmental temperature, the two brown adipocyte subpopulations underwent dynamic inter-conversions. Cold exposure converted low thermogenic brown adipocytes into high thermogenic cells, and a thermoneutral environment had the opposite effect. This recruitment of high thermogenic brown adipocytes by cold stimulation is not affected by high fat diet feeding, but significantly declined with age. Our results revealed a high degree of functional heterogeneity of brown adipocytes.

Authors

Anying Song, Wenting Dai, Min Jee Jang, Leonard Medrano, Zhuo Li, Hu Zhao, Mengle Shao, Jiayi Tan, Aimin Li, Tinglu Ning, Marcia M. Miller, Brian Armstrong, Janice M. Huss, Yi Zhu, Yong Liu, Viviana Gradinaru, Xiwei Wu, Lei Jiang, Philipp E. Scherer, Qiong A. Wang

β2 Adrenergic receptor-mediated signaling regulates the immunosuppressive potential of myeloid-derived suppressor cells

• Text
• PDF

Abstract

Catecholamines released by sympathetic nerves can activate adrenergic receptors present on nearly every cell type, including myeloid derived suppressor cells (MDSCs). Using in vitro systems and murine tumor models, in wild-type mice and genetically modified (β2-AR–/–) mice, as well adoptive transfer approaches, we found that the degree of β2-AR signaling significantly influences MDSC frequency and survival in tumors and other tissues, modulates their expression of immunosuppressive molecules such as arginase-I and PDL-1 and alters their ability to suppress the proliferation of T cells. The regulatory functions of β-AR signaling in MDSCs were found to be dependent upon STAT3 phosphorylation. Moreover, we observed that the β2-AR-mediated increase in survival of MDSCs is dependent upon Fas-FasL interactions, and this is consistent with gene expression analyses which reveal a greater expression of apoptosis-related genes in β2-AR–/– MDSCs. Our data reveals the potential of β2-AR signaling to increase the generation of MDSCs from both murine and human peripheral blood cells and that the immunosuppressive function of MDSCs could be mitigated by treatment with β-AR antagonists, or enhanced by β-AR agonists, strongly supporting the possibility that reducing stress-induced activation of β2-ARs could help to overcome immune suppression and enhance the efficacy of immunotherapy and other cancer therapies.

Authors

Hemn Mohammadpour, Cameron R. MacDonald, Guanxi Qiao, Minhui Chen, Bowen Dong, Bonnie L. Hylander, Philip L. McCarthy, Scott I. Abrams, Elizabeth A. Repasky