Idiopathic inflammatory myopathies (IIM) involve chronic inflammation of skeletal muscle and subsequent muscle degeneration due to an uncontrolled autoimmune response; however, the mechanisms leading to pathogenesis are not well understood. A compromised sarcolemmal repair process could promote an aberrant exposure of intramuscular antigens with the subsequent initiation of an inflammatory response that contributes to IIM. Using an adoptive transfer mouse model of IIM, we show that sarcolemmal repair is significantly compromised in distal skeletal muscle in the absence of inflammation. We identified autoantibodies against TRIM72 (also known as MG53), a muscle-enriched membrane repair protein, in IIM patient sera and in our mouse model of IIM by ELISA. We found that patient sera with elevated levels of TRIM72 autoantibodies suppress sarcolemmal resealing in healthy skeletal muscle, and depletion of TRIM72 antibodies from these same serum samples rescues sarcolemmal repair capacity. Autoantibodies targeting TRIM72 lead to skeletal muscle fibers with compromised membrane barrier function, providing a continuous source of autoantigens to promote autoimmunity and further amplifying humoral responses. These findings reveal a potential pathogenic mechanism that acts as a feedback loop contributing to the progression of IIM.
Kevin E. McElhanon, Nicholas Young, Jeffrey Hampton, Brian J. Paleo, Thomas A. Kwiatkowski, Eric X Beck, Ana Capati, Kyle Jablonski, Travis Gurney, Miguel A. Lopez Perez, Rohit Aggarwal, Chester V. Oddis, Wael N. Jarjour, Noah Weisleder
BACKGROUND. Idiopathic CD4 lymphopenia (ICL) is defined by persistent low CD4 counts (<300 cells/µL) in the absence of a causal infection or immune deficiency and can manifest with opportunistic infections. Approximately 30% of ICL patients develop autoimmune disease. The prevalence and breadth of their autoantibodies, however, and their potential contribution to pathogenesis of ICL remain unclear. METHODS. We hybridized 35 and 51 ICL patients’ sera to a 9,000 human proteome array and to a 128 known autoantigens array, respectively. Using a flow-based method, we characterized the presence of anti-lymphocyte Ab in the whole cohort of 72 patients, as well as the Ab functional capability of inducing antibody-dependent cell-mediated cytotoxicity (ADCC), complement deposition, and complement dependent cytotoxicity (CDC). We tested ex vivo the activation of the classical complement pathway on ICL CD4 T cells. RESULTS. All ICL patients had multitude of autoantibodies mostly directed against private (not shared) targets and unrelated quantitatively or qualitatively to the patients’ autoimmune disease status. The targets included lymphocyte intracellular and membrane antigens, confirmed by the detection by flow of IgM and IgG (mostly IgG1 and IgG4) anti-CD4 cell Ab in 50% of the patients with half of these cases triggering lysis of CD4 T cells. We also detected in vivo classical complement activation on CD4 T cells in 14% of the whole cohort. CONCLUSION. Our data demonstrate a high prevalence of autoantibodies in ICL, some of which are specific against CD4 T cells, may contribute to pathogenesis and may represent a potential novel therapeutic target.
Ainhoa Perez-Diez, Chun-Shu Wong, Xiangdong Liu, Harry A. Mystakelis, Jian song, Yong Lu, Virginia Sheikh, Jeffrey S. Bourgeois, Andrea Lisco, Elizabeth Laidlaw, Cornelia D. Cudrici, Chengsong Zhu, Quan-Zhen Li, Alexandra F. Freeman, Peter R. Williamson, Megan V. Anderson, Gregg Roby, John S. Tsang, Richard M. Siegel, Irini Sereti
TGFβ is a master regulator of fibrosis, driving the differentiation of fibroblasts into apoptosis resistant myofibroblasts and sustaining the production of extracellular matrix (ECM) components. Here, we identify the nuclear lncRNA H19X as a master regulator of TGFβ-driven tissue fibrosis. H19X was consistently upregulated in a wide variety of human fibrotic tissues and diseases and was strongly induced by TGFβ, particularly in fibroblasts and fibroblast-related cells. Functional experiments following H19X silencing revealed that H19X is an obligatory factor for the TGFβ-induced ECM synthesis as well as differentiation and survival of ECM-producing myofibroblasts. We showed that H19X regulates DDIT4L gene expression, specifically interacting with a region upstream of DDIT4L gene and changing the chromatin accessibility of a DDIT4L enhancer. These events resulted in transcriptional repression of DDIT4L and, in turn, in increased collagen expression and fibrosis. Our results shed light on key effectors of the TGFβ-induced ECM remodeling and fibrosis.
Elena Pachera, Shervin Assassi, Gloria A. Salazar, Mara Stellato, Florian Renoux, Adam Wunderlin, Przemyslaw Blyszczuk, Robert Lafyatis, Fina Kurreeman, Jeska de Vries-Bouwstra, Tobias Messemaker, Carol A. Feghali-Bostwick, Gerhard Rogler, Wouter T. van Haaften, Gerard Dijkstra, Fiona Oakley, Maurizio Calcagni, Janine Schniering, Britta Maurer, Jörg H.W. Distler, Gabriela Kania, Mojca Frank-Bertoncelj, Oliver Distler
Neuromyelitis optica (NMO) is a severe inflammatory autoimmune CNS disorder triggered by binding of an IgG autoantibody to the aquaporin 4 (AQP4) water channel on astrocytes. Activation of cytolytic complement has been implicated as the major effector of tissue destruction that secondarily involves myelin. We investigated early precytolytic events in the evolving pathophysiology of NMO in mice by continuously infusing IgG (NMO patient serum–derived or AQP4-specific mouse monoclonal), without exogenous complement, into the spinal subarachnoid space. Motor impairment and sublytic NMO-compatible immunopathology were IgG dose dependent, AQP4 dependent, and, unexpectedly, microglia dependent. In vivo spinal cord imaging revealed a striking physical interaction between microglia and astrocytes that required signaling from astrocytes by the C3a fragment of their upregulated complement C3 protein. Astrocytes remained viable but lost AQP4. Previously unappreciated crosstalk between astrocytes and microglia involving early-activated CNS-intrinsic complement components and microglial C3a receptor signaling appears to be a critical driver of the precytolytic phase in the evolving NMO lesion, including initial motor impairment. Our results indicate that microglia merit consideration as a potential target for NMO therapeutic intervention.
Tingjun Chen, Vanda A. Lennon, Yong U. Liu, Dale B. Bosco, Yujiao Li, Min-Hee Yi, Jia Zhu, Shihui Wei, Long-Jun Wu
Patients with common variable immunodeficiency associated with autoimmune cytopenias (CVID+AIC) generate few isotype-switched B cells with severely decreased frequencies of somatic hypermutations (SHM) but their underlying molecular defects remain poorly characterized. We identified a CVID+AIC patient who displays a rare homozygous missense M466V mutation in the beta catenin-like protein 1 (CTNNBL1). Since CTNNBL1 binds activation-induced cytidine deaminase (AID) that catalyzes SHM, we tested AID interactions with the CTNNBL1 M466V variant. We found that the M466V mutation interfered with the association of CTNNBL1 with AID, resulting in decreased AID in the nucleus of patient EBV-transformed B cell lines and of CTNNBL1 466V/V Ramos B cells engineered to only express M466V CTNNBL1 using CRISPR/Cas9 technology. As a consequence, the scarce IgG+ memory B cells from the CTNNBL1 466V/V patient showed a low SHM frequency that averaged 6.7 mutations compared to about 18 mutations per clone in healthy donor counterparts. In addition, CTNNBL1 466V/V Ramos B cells displayed a decreased incidence of SHM that was reduced by half compared to parental wild-type Ramos B cells, demonstrating that the CTNNBL1 M466V mutation is responsible for defective SHM induction. We conclude that CTNNBL1 plays an important role in regulating AID-dependent antibody diversification in humans.
Marcel Kuhny, Lisa R. Forbes, Elif Çakan, Andrea Vega-Loza, Valentyna Kostiuk, Ravi K. Dinesh, Salomé Glauzy, Asbjorg Stray-Pedersen, Ashley E. Pezzi, I. Celine Hanson, Alexander Vargas-Hernandez, Mina LuQuing Xu, Zeynep H. Coban Akdemir, Shalini N. Jhangiani, Donna M. Muzny, Richard A. Gibbs, James R. Lupski, Ivan K. Chinn, David G. Schatz, Jordan S. Orange, Eric Meffre
Despite recent advances in understanding chronic inflammation remission, global analyses have not been explored to systematically discover genes or pathways underlying the resolution dynamics of chronic inflammatory diseases. Here, we performed time-course gene expression profiling of mouse synovial tissues along progression and resolution of collagen-induced arthritis (CIA) and identified genes associated with inflammation resolution. Through network analysis of these genes, we predicted three key secretory factors responsible for the resolution of CIA: Itgb1, Rps3, and Ywhaz. These factors were predominantly expressed by regulatory T cells and anti-inflammatory M2 macrophages, suppressing production of pro-inflammatory cytokines. In particular, Ywhaz was elevated in the sera of mice with arthritis resolution and in the urine of rheumatoid arthritis (RA) patients with good therapeutic responses. Moreover, adenovirus-mediated transfer of the Ywhaz gene to the affected joints substantially inhibited arthritis progression in mice with CIA and suppressed expression of pro-inflammatory cytokines in joint tissues, lymph nodes, and spleens, suggesting Ywhaz as an excellent target for RA therapy. Therefore, our comprehensive analysis of dynamic synovial transcriptomes provides previously unidentified anti-arthritic genes, Itgb1, Rps3, and Ywhaz, which can serve as molecular markers to predict disease remission, as well as therapeutic targets for chronic inflammatory arthritis.
Jin-Sun Kong, Ji-Hwan Park, Seung-Ah Yoo, Ki-Myo Kim, Yeung-Jin Bae, Yune-Jung Park, Chul-Soo Cho, Daehee Hwang, Wan-Uk Kim
Toll-like receptor 9 (TLR9) is a regulator of disease pathogenesis in systemic lupus erythematosus (SLE). Why TLR9 represses disease while TLR7 and MyD88 have the opposite effect remains undefined. To begin to address this question, we created two novel alleles to manipulate TLR9 expression, allowing for either selective deletion or overexpression. We used these to test cell type-specific effects of Tlr9 expression on the regulation of SLE pathogenesis. Notably, Tlr9 deficiency in B cells was sufficient to exacerbate nephritis while extinguishing anti-nucleosome antibodies, whereas Tlr9 deficiency in dendritic cells (DCs), plasmacytoid DCs, and neutrophils had no discernable effect on disease. Thus, B cell-specific Tlr9 deficiency unlinked disease from autoantibody production. Critically, B cell-specific Tlr9 overexpression resulted in ameliorated nephritis, opposite of the effect of deleting Tlr9. Our findings highlight the non-redundant role of B cell-expressed TLR9 in regulating lupus and suggests therapeutic potential in modulating and perhaps even enhancing TLR9 signals in B cells.
Jeremy S. Tilstra, Shinu John, Rachael A. Gordon, Claire Leibler, Michael Kashgarian, Sheldon Bastacky, Kevin M. Nickerson, Mark J. Shlomchik
Single nucleotide polymorphisms and locus amplification link the NF-κB transcription factor c-Rel to human autoimmune diseases and B cell lymphomas, respectively. However, the functional consequences of enhanced c-Rel levels remain enigmatic. Here, we overexpressed c-Rel specifically in mouse B cells from BAC-transgenic gene loci and demonstrate that c-Rel protein levels linearly dictated expansion of germinal center (GC) B cells and isotype-switched plasma cells. c-Rel expression in B cells of otherwise c-Rel-deficient mice fully rescued terminal B cell differentiation, underscoring its critical B cell-intrinsic roles. Unexpectedly, in GCB cells transcription-independent regulation produced the highest c-Rel protein levels amongst B cell subsets. In c-Rel overexpressing GCB cells this caused enhanced nuclear translocation, a profoundly altered transcriptional program and increased proliferation. Finally, we provide a link between c-Rel gain and autoimmunity by showing that c-Rel overexpression in B cells caused autoantibody production and renal immune complex deposition.
Maike Kober-Hasslacher, Hyunju Oh-Strauß, Dilip Kumar, Valeria Soberón, Carina Diehl, Maciej Lech, Thomas Engleitner, Eslam Katab, Vanesa Fernandez Saiz, Guido Piontek, Hongwei Li, Björn Menze, Christoph Ziegenhain, Wolfgang Enard, Roland Rad, Jan P. Böttcher, Hans-Joachim Anders, Martina Rudelius, Marc Schmidt-Supprian
T follicular helper (Tfh) cells are indispensable for the formation of germinal center (GC) reactions, while T follicular regulatory (Tfr) cells inhibit Tfh-mediated GC responses. Aberrant activation of Tfh cells contributes significantly to the pathogenesis of autoimmune diseases, such as systemic lupus erythematosus (SLE). Nonetheless, the molecular mechanisms mitigating excessive Tfh cell differentiation, which in turn trigger autoimmunity, are not fully understood. Herein we demonstrate that the adenovirus E4 promoter-binding protein (E4BP4) mediates a feedback loop and acts as a transcriptional brake to inhibit Tfh cell differentiation. Furthermore, we show that such an immunological mechanism is compromised in patients with SLE. Establishing mice with either conditional knock-out (cKO) or knock-in (cKI) of the E4bp4 gene in T cells reveals that E4BP4 strongly inhibits Tfh cell differentiation. Mechanistically, E4BP4 deregulates Bcl6 transcription by recruiting the repressive epigenetic modifiers HDAC1 and EZH2. E4BP4 phosphorylation site mutants had limited capability with regard to inhibiting Tfh cell differentiation. In SLE, we detected impaired phosphorylation of E4BP4, finding that this compromised transcription factor is positively correlated with disease activity. These findings unveiled molecular mechanisms by which E4BP4 restrains Tfh cell differentiation, whose compromised function is associated with uncontrolled autoimmune reactions in SLE.
Zijun Wang, Ming Zhao, Jinghua Yin, Limin Liu, Longyuan Hu, Yi Huang, Aiyun Liu, Jiajun Ouyang, Xiaoli Min, Shijia Rao, Wenhui Zhou, Haijing Wu, Akihiko Yoshimura, Qianjin Lu
Spondyloarthritis (SpA) represents a family of inflammatory diseases of the spine and peripheral joints. Ankylosing spondylitis (AS) is the prototypic form of SpA in which progressive disease can lead to fusion of the spine. Therapeutically, knowledge of type 3 immunity has translated into the development of IL-23– and IL-17A–blocking antibodies for the treatment of SpA. Despite being able to provide symptomatic control, the current biologics do not prevent the fusion of joints in AS patients. Thus, there is an unmet need for disease-modifying drugs. Genetic studies have linked the Janus kinase TYK2 to AS. TYK2 is a mediator of type 3 immunity through intracellular signaling of IL-23. Here, we describe and characterize a potentially novel small-molecule inhibitor of TYK2 that blocked IL-23 signaling in vitro and inhibited disease progression in animal models of SpA. The effect of the inhibitor appears to be TYK2 specific, using TYK2-inactive mice, which further revealed a duality in the induction of IL-17A and IL-22 by IL-23. Specifically, IL-22 production was TYK2/JAK2/STAT3 dependent, while IL-17A was mostly JAK2 dependent. Finally, we examined the effects of AS-associated TYK2 SNPs on TYK2 expression and function and correlated them with AS disease progression. This work provides evidence that TYK2 inhibitors have great potential as an orally delivered therapeutic for SpA.
Eric Gracey, Dominika Hromadová, Melissa Lim, Zoya Qaiyum, Michael Zeng, Yuchen Yao, Archita Srinath, Yuriy Baglaenko, Natalia Yeremenko, William Westlin, Craig Masse, Mathias Müller, Birgit Strobl, Wenyan Miao, Robert D. Inman
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