MuSK cysteine-rich domain antibodies are pathogenic in a mouse model of autoimmune myasthenia gravis

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Abstract

The neuromuscular junction (NMJ), synapse between the motor neuron terminal and a skeletal muscle fiber is crucial, throughout life, in maintaining the reliable neurotransmission required for functional motricity. Disruption of this system leads to neuromuscular disorders, such as auto-immune myasthenia gravis (MG), the most common form of NMJ diseases. MG is caused by autoantibodies directed mostly against the acetylcholine receptor (AChR) or the muscle-specific kinase MuSK. Several studies report immunoreactivity to the Frizzled-like cysteine-rich Wnt-binding domain of MuSK (CRD) in patients, although the pathogenicity of the antibodies involved remains unknown. We showed here that the immunoreactivity to MuSK CRD induced by the passive transfer of anti-MuSKCRD antibodies in mice led to typical MG symptoms, characterized by a loss of body weight and a locomotor deficit. The functional and morphological integrity of the NMJ was compromised with a progressive decay of neurotransmission and disruption of the structure of pre- and post-synaptic compartments. We found that anti-MuSKCRD antibodies completely abolished Agrin-mediated AChR clustering by decreasing the Lrp4-MuSK interaction. These results provide the first demonstration of the role of the MuSK CRD in MG pathogenesis and improve our understanding of the underlying pathophysiological mechanisms.

Authors

Marius Halliez, Steve Cottin, Axel You, Céline Buon, Antony Grondin, Léa S. Lippens, Megane Lemaitre, Jérome Ezan, Charlotte Isch, Yann Rufin, Mireille Montcouquiol, Nathalie Sans, Bertrand Fontaine, Julien Messéant, Rozen Le Panse, Laure Strochlic

B cell deficiency induces cytotoxic memory CD8⁺ T cells during influenza-associated bacterial pneumonia

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Abstract

Influenza-associated bacterial super-infections in the lung lead to increased morbidity and mortality. Nearly all people have pre-existing memory to influenza virus, which can protect against subsequent infection in the lung. This study explored the role B cells play in protection against bacterial (Staphylococcus aureus or Klebsiella pneumoniae) super-infection with previous heterotypic influenza memory. B cell deficiency resulted in an increased inflammatory lung environment and lung tissue injury during super-infection. Loss of B cells increased populations of memory CD8+ T cells in the lung and these CD8+ T cells were transcriptionally and functionally distinct from WT mice. Use of antibody-deficient mouse models showed that this phenotype was specifically due to loss of antibody production from B cells. Passive immunization with influenza-antibody serum in B cell deficient mice rescued the CD8+ T cell phenotype. CD8+ T cell depletion and lethal super-infection challenge experiments showed that the cytotoxic memory CD8+ T cells from B cell deficient mice protect against super-infection bacterial burden and mortality. These findings provide insight into the importance of B cells for regulating immune responses against infection.

Authors

Leigh M. Miller, Alexis M. Duray, Ellyse M. Cipolla, Flavia Rago, Brooke P. Dresden, Kristen L. Parenteau, Abhigya Gupta, John F. Alcorn

CXCL10 secreted by SPRY1-deficient epidermal keratinocytes fuels joint inflammation in psoriatic arthritis via CD14 signaling

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Abstract

Psoriatic arthritis (PsA) is a multifaceted chronic inflammatory disease affecting the skin, joints, and entheses, and is a major comorbidity of psoriasis. Most patients with PsA present with psoriasis before articular involvement, however, the molecular and cellular mechanisms underlying the link between cutaneous psoriasis and PsA are poorly understood. Here, we found that epidermal-specific SPRY1-deficient mice spontaneously developed PsA-like inflammation involving both the skin and joints. Excessive CXCL10 was secreted by SPRY1-deficient epidermal keratinocytes through enhanced activation of JAK1/2-STAT1 signaling, and CXCL10 blockade attenuated PsA-like inflammation. Of note, CXCL10 was found to bind to CD14, but not CXCR3, to promote the TNF𝜶 production of periarticular CD14hi macrophages via PI3K/AKT and NF-κB signaling pathways. Collectively, this study reveals that SPRY1 deficiency in the epidermis is sufficient to drive both skin and joint inflammation, and identifies keratinocyte-derived CXCL10 and periarticular CD14hi macrophages as critical links in the skin-joint crosstalk leading to PsA. This keratinocyte SPRY1-CXCL10-periarticular CD14hi macrophages-TNFα axis provides valuable insights into the mechanisms underlying the transition from psoriasis to PsA and suggests potential therapeutic targets for preventing this progression.

Authors

Fan Xu, Ying-Zhe Cui, Xing-Yu Yang, Yu-Xin Zheng, Xi-Bei Chen, Hao Zhou, Zhao-Yuan Wang, Yuan Zhou, Yi Lu, Ying-Ying Li, Li-Ran Ye, Ni-Chang Fu, Si-Qi Chen, Xue-Yan Chen, Min Zheng, Yong Yang, Xiao-Yong Man

Tumor microenvironment of non-small cell lung cancer impairs immune cell function among people with HIV

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Abstract

Lung cancer is the leading cause of cancer mortality among people with HIV (PWH), with increased incidence and poor outcomes. This study explored whether the tumor microenvironment (TME) of HIV-associated non-small cell lung cancer (NSCLC) limits tumor-specific immune responses. With a matched cohort of NSCLC from PWH and people without HIV (PWOH), we used imaging mass cytometry, linear mixed effects model and AI-based pageRank mathematical algorithm based on spectral graph theory to demonstrate that HIV-associated tumors demonstrate differential distribution of tumor infiltrating CD8+ and CD4+ T cells, enriched for the expression of PD-1 and Lag-3, as well as activation and proliferation markers. We also demonstrate higher expression of immunoregulatory molecules (PD-L1, PD-L2, B7-H3, B7-H4, IDO1 and VISTA), among tumor-associated macrophages. Discrimination of cells between tumors from PWH versus PWOH was confirmed by spectral graph theory with 84.6% accuracy. Furthermore, we noted differences in spatial orientation of immune cells within the TME of PWH compared to PWOH. Additionally, cells from PWH, compared to PWOH, exhibited decreased tumor killing when exposed to HLA-matched NSCLC cell lines. In conclusion, our study demonstrates that the HIV-associated tumor microenvironment sustains a unique immune landscape, with evidence of immune cells with enhanced immunoregulatory phenotypes and impaired anti-tumor responses, with implications for response to immune checkpoint blocker therapies.

Authors

Shruti S. Desai, Syim Salahuddin, Ramsey Yusuf, Kishu Ranjan, Jianlei Gu, Lais Osmani, Ya-Wei Eileen Lin, Sameet Mehta, Ronen Talmon, Insoo Kang, Yuval Kluger, Hongyu Zhao, Kurt A. Schalper, Brinda Emu

Immune cells promote paralytic disease in mice infected with enterovirus D68

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Abstract

Enterovirus D68 (EV-D68) is associated with acute flaccid myelitis (AFM), a poliomyelitis-like illness causing paralysis in young children. However, mechanisms of paralysis are unclear, and antiviral therapies are lacking. To better understand EV-D68 disease, we inoculated newborn mice intracranially to assess viral tropism, virulence, and immune responses. Wild-type (WT) mice inoculated intracranially with a neurovirulent strain of EV-D68 showed infection of spinal cord neurons and developed paralysis. Spinal tissue from infected mice revealed increased chemokines, inflammatory monocytes, macrophages, and T cells relative to controls, suggesting that immune cell infiltration influences pathogenesis. To define the contribution of cytokine-mediated immune cell recruitment to disease, we inoculated mice lacking CCR2, a receptor for several EV-D68-upregulated cytokines, or RAG1, which is required for lymphocyte maturation. WT, Ccr2-/-, and Rag1-/- mice had comparable viral titers in spinal tissue. However, Ccr2-/- and Rag1-/- mice were significantly less likely to be paralyzed relative to WT mice. Consistent with impaired T cell recruitment to sites of infection in Ccr2-/- and Rag1 -/- mice, antibody-mediated depletion of CD4+ or CD8+ T cells from WT mice diminished paralysis. These results indicate that immune cell recruitment to the spinal cord promotes EV-D68-associated paralysis and illuminate new targets for therapeutic intervention.

Authors

Mikal A. Woods Acevedo, Jie Lan, Sarah Maya, Jennifer E. Jones, Isabella E. Bosco, John V. Williams, Megan C. Freeman, Terence S. Dermody

PIEZO1 mediates mechanical reprogramming of neutrophils for proangiogenic specialization in the lung

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Abstract

Neutrophils are the most abundant immune cells that constantly patrol or marginate inside vascular beds to support immune homeostasis. The extent to which neutrophils undergo reprogramming in response to the changes in vascular architecture and the resultant biological implications of such adaptations remain unclear. Here, we performed intravital imaging and transcriptional profiling to investigate neutrophil behavior across different tissues. Our findings revealed that neutrophils had significant deformability and spontaneous calcium signaling while navigating through the narrow pulmonary vessels. Pulmonary neutrophils exhibited unique transcriptional profiles and were specialized for proangiogenic functions. We found that the mechanosensitive ion channel Piezo-type mechanosensitive ion channel component 1 (PIEZO1) was essential for neutrophil reprogramming. Deletion of Piezo1 in neutrophils ablated the lung-specific proangiogenic transcriptional signature and impaired capillary angiogenesis in both physiological and pathological conditions. Collectively, these data show that mechanical adaptation of neutrophils within the pulmonary vasculature drives their reprogramming in the lungs and promotes pulmonary vascular homeostasis.

Authors

Jin Wang, Wenying Zhao, Wenjuan Bai, Dong Dong, Hui Wang, Xin Qi, Ajitha Thanabalasuriar, Youqiong Ye, Tian-le Xu, Hecheng Li, Paul Kubes, Bin Li, Jing Wang

Chemotaxis overrides killing response in alloreactive cytotoxic T-cells providing vascular immune privilege during cellular rejection

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Abstract

Graft endothelial cells (ECs) express donor alloantigens and encounter cytotoxic T lymphocytes (CTLs) but are generally spared during T cell-mediated rejection (TCMR), which predominantly affects epithelial structures. The mechanisms underlying this vascular immune privilege are unclear. Transcriptomic analyses and endothelial-mesenchymal transition assessments confirmed that the graft endothelium is preserved during TCMR. Co-culture experiments revealed that endothelial and epithelial cells are equally susceptible to CTL-mediated lysis, ruling out cell-intrinsic protection. Intravital microscopy of murine kidney grafts and single-cell RNA sequencing of human renal allografts demonstrated that CTL interactions with ECs are transient compared to epithelial cells. This disparity is mediated by a chemotactic gradient produced by graft stromal cells, guiding CTLs away from ECs toward epithelial targets. In vitro, chemotaxis overrode TCR-induced cytotoxicity, preventing endothelial damage. Finally, analysis of TCMR biopsies revealed that disruption of the chemotactic gradient correlates with endothelialitis lesions, linking its loss to vascular damage. These findings challenge the traditional view of cell-intrinsic immune privilege, proposing a cell-extrinsic mechanism where chemotaxis preserves graft vasculature during TCMR. This mechanism may have implications beyond transplantation, highlighting its role in maintaining vascular integrity across pathological conditions.

Authors

T. Barba, M. Oberbarnscheidt, G. Franck, C. Gao, S. This, M. Rabeyrin, C. Roufosse, L. Moran, A. Koenig, V. Mathias, C. Saison, V. Dubois, N. Pallet, D. Anglicheau, B. Lamarthée, A. Hertig, E. Morelon, A Hot, H. Paidassi, T. Defrance, A. Nicoletti, J.P. Duong-Van-Huyen, Y. Xu-Dubois, F.G. Lakkis, O. Thaunat

Autophagy is an upstream mediator of chromatin dynamics in normal and autoimmune germinal centre B cells

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Abstract

Germinal centre (GC) B cells are pivotal in establishing a robust humoral immune response and long-term serological immunity while maintaining antibody self-tolerance. GC B cells rely on autophagy for antigen presentation and homeostatic maintenance. However, these functions, primarily associated with the light zone, cannot explain the spatiotemporal autophagy upregulation in the dark zone of GCs. Here, we define a functional mechanism controlling chromatin accessibility in GC B cells during their dark zone transition. This mechanism links autophagy and nuclear Lamin B1 dynamics with their downstream effects, including somatic hypermutation and antibody affinity maturation. Moreover, the autophagy-Lamin B1 axis is highly active in the aberrant ectopic germinal centres in the salivary glands of Sjogren’s disease, defining its role in autoimmunity.

Authors

Marta C Sallan, Filip Filipsky, Christina H. Shi, Elena Pontarini, Manuela Terranova-Barberio, Gordon Beattie, Andrew Clear, Michele Bombardieri, Kevin Y. Yip, Dinis Parente Calado, Mark S. Cragg, Sonya James, Matthew J. Carter, Jessica Okosun, John G. Gribben, Tanya Klymenko, Andrejs Braun

ST6GalNAc-I regulates tumor cell sialylation via NECTIN2/MUC5AC-mediated immunosuppression and angiogenesis in non–small cell lung cancer

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Abstract

Glycosylation controls immune evasion, tumor progression, and metastasis. However, how tumor cell sialylation regulates immune evasion remains poorly characterized. ST6GalNAc-I, a sialyltransferase that conjugates sialic acid to the glycans in glycoproteins, was overexpressed in an aggressive-type KPA (KrasG12D/+ Trp53R172H/+ Ad-Cre) lung adenocarcinoma (LUAD) model and patient samples. Proteomic and biochemical analysis indicated that ST6GalNAc-I mediated NECTIN2 sialylation in LUAD cells. ST6GalNAc-I–deficient tumor cells cocultured with T cells were more susceptible to T cell–mediated tumor cell killing, indicating a key role for NECTIN2 in T cell dysfunction. Mice injected with St6galnac-I–knockdown syngeneic cells showed reduced lung tumor incidence and Nectin2/Tigit-associated immunosuppression. ST6GalNAc-I–deficient cells exhibited reduced P-DMEA metabolite levels, while administration of P-DMEA promoted LUAD cell proliferation via MUC5AC. MUC5AC interacted and colocalized with PRRC1 in the Golgi, suggesting a potential role for PRRC1 in MUC5AC glycosylation. Mice injected with ST6GalNAc-I/MUC5AC-deficient cells (human LUAD) exhibited reduced lung tumor incidence, angiogenesis, and liver metastases. Mechanistically, ST6GalNAc-I/MUC5AC regulates VCAN-V1, a key factor in tumor matrix remodeling during angiogenesis and metastasis. These findings demonstrate that ST6GalNAc-I–mediated sialylation of NECTIN2/MUC5AC is critical for immune evasion and tumor angiogenesis. Targeting this pathway may prevent LUAD development and/or metastasis.

Authors

Muthamil Iniyan Appadurai, Sanjib Chaudhary, Ashu Shah, Gopalakrishnan Natarajan, Zahraa W. Alsafwani, Parvez Khan, Dhananjay D. Shinde, Subodh M. Lele, Lynette M. Smith, Mohd Wasim Nasser, Surinder Kumar Batra, Apar Kishor Ganti, Imayavaramban Lakshmanan

Clemastine fumarate accelerates accumulation of disability in progressive multiple sclerosis by enhancing pyroptosis

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Abstract

Multiple sclerosis (MS) is an immune-mediated demyelinating disease of the CNS. Clemastine fumarate, the over-the-counter antihistamine and muscarinic receptor blocker, has remyelinating potential in MS. A clemastine arm was added to an ongoing platform clinical trial, targeting residual activity by precision, biomarker-guided combination therapies of multiple sclerosis (TRAP-MS) (ClinicalTrials.gov NCT03109288), to identify a cerebrospinal fluid (CSF) remyelination signature and to collect safety data on clemastine in patients progressing independently of relapse activity (PIRA). The clemastine arm was stopped per protocol-defined criteria when 3 of 9 patients triggered individual safety stopping criteria. Clemastine-treated patients had significantly higher treatment-induced disability progression slopes compared with the remaining TRAP-MS participants. Quantification of approximately 7,000 proteins in CSF samples collected before and after clemastine treatment showed significant increases in purinergic signaling and pyroptosis. Mechanistic studies showed that clemastine with sublytic doses of extracellular adenosine triphosphate (ATP) activates inflammasome and induces pyroptotic cell death in macrophages. Clemastine with ATP also caused pyroptosis of induced pluripotent stem cell–derived human oligodendrocytes. Antagonist of the purinergic channel P2RX7, which is strongly expressed in oligodendrocytes and myeloid cells, blocked these toxic effects of clemastine. Finally, reanalysis of published single-nucleus RNA-Seq (snRNA-Seq) studies revealed increased P2RX7 expression and pyroptosis transcriptional signature in microglia and oligodendrocytes in the MS brain, especially in chronic active lesions. The CSF proteomic pyroptosis score was increased in untreated MS patients, was higher in patients with progressive than relapsing-remitting disease, and correlated significantly with the rates of MS progression. Collectively, this identifies pyroptosis as a likely mechanism of CNS injury underlying PIRA even outside of clemastine toxicity.

Authors

Joanna Kocot, Peter Kosa, Shinji Ashida, Nicolette A. Pirjanian, Raphaela Goldbach-Mansky, Karin Peterson, Valentina Fossati, Steven M. Holland, Bibiana Bielekova