Autoimmunity
Abstract
Fibroblast-like synoviocytes (FLSs) are crucial in driving synovial inflammation and joint damage in rheumatoid arthritis (RA). This study explored the functions and underlying mechanisms of GALNT1-mediated O-glycosylation, which is markedly upregulated in RA FLSs, in synovial aggression and subsequent experimental joint damage. Targeted suppression of GALNT1 effectively curtailed migration and invasion in RA FLSs and mitigated arthritis severity in a rat collagen-induced arthritis (CIA) model. Mechanistically, NEK9 was identified as a pivotal substrate and downstream effector of GALNT1, affecting the aggressive phenotype of RA FLSs. In vitro experiments further demonstrated that O-glycosylation of NEK9, mediated by GALNT1, promotes the pathogenic phenotype of RA FLSs by promoting cytoskeleton reorganization and restraining excessive endoplasmic reticulum (ER) stress activation. Our study provides mechanistic insights into the activation of RA FLSs and identifies GALNT1 as a potential therapeutic target for RA.
Authors
Yaoyao Zou, Haobo Lin, Jianling Su, Jieying Wang, Qin Zeng, Tianxiao Feng, Yunxia Lei, Jianda Ma, Hudan Pan, Hanshi Xu, Lie Dai, Yang Li
Abstract
Primary sclerosing cholangitis (PSC) is a chronic, idiopathic cholestatic liver disease characterized by inflammation and fibrosis of the bile ducts, yet the cellular crosstalk driving periductal fibrosis remains poorly defined. This study applied a multi-omics approach integrating spatial transcriptomics, RNA-seq, and proteomics to characterize fibrotic periductal regions and their cell–cell communications. Macrophages (MP) subsets, including monocyte-drived-(Mo)MP and lipid-associated-macrophage (LAM)-like, co-localized with cholangiocytes, lymphocytes, and hepatic stellate cells (HSC1). Cell niche analysis identified periductal regions with elevated fibrotic signals, where cell–cell communication analysis revealed potential MP–HSC interactions involving 17 fibrotic driver genes in MP, including ITGB2, GRN, and CCL21, and 6 fibrotic effector genes in HSC. In validation analyses, bulk RNA-seq data showed higher driver and effector gene expression in PSC with established fibrosis compared to early-stage PSC or healthy control (HC). Plasma proteins encoded by MP driver genes were elevated in PSC and in patients with elevated (≥3.29 kPa) liver stiffness on MR elastography. Furthermore, immunofluorescence and SHG imaging showed enrichment of CD68+/CD18+(ITGB2) macrophages in fibrotic regions of PSC liver biopsies. These findings revealed enrichment of MoMP and LAM-like macrophages in fibrotic regions and suggest that they likely contribute to fibrotic activation of nearby HSCs in PSC.
Authors
Yunguan Wang, David Adeleke, Xiangfei Xie, Zi F. Yang, Xiangya Wang, Giulia Loi, Annika Yang vom Hofe, Manavi Singh, Astha Malik, Ramesh Kudira, Cyd Castro-Rojas, Liva Pfuhler, Mosab Alquraish, Pamela Sylvestre, Jonathan R. Dillman, Andrew T. Trout, Emily R. Miraldi, Alexander G. Miethke
Abstract
IL-10–producing B cells exert immunosuppressive effects, yet their low abundance and poor in vitro viability have limited their therapeutic application. Here, we developed a stromal coculture system using MS5 cells engineered to express human CD40L, BAFF, and IFN-β1 (MS5-3F, for “3 factors”), which enables robust induction and greater than 1000-fold expansion of human IL-10–producing B cells. The expanded cells showed phenotypic and transcriptional profiles characteristic of unswitched (IgM+) plasmablasts and potently suppressed CD4+ T cell proliferation in an IL-10–dependent manner. MS5-3F–expanded B cells also increased the frequency of regulatory T cells in vitro, an effect that was not abrogated by IL-10/IL-10R blockade, suggesting contributions from additional mechanisms. IL-10 production originated predominantly from naive B cells, rather than memory B cells. Furthermore, B cells from patients with systemic lupus erythematosus, despite impaired IL-10 production under conventional conditions, were efficiently differentiated into IL-10–producing B cells using this system. The expanded cells showed minimal IgG-secreting output. Our platform offers a scalable strategy for generating human regulatory B cells, laying the foundation for B cell–based immunotherapies.
Authors
Ryo Kawakami, Keisuke Imabayashi, Akemi Baba, Yuichi Saito, Kazuhiko Kawata, Yutaro Yada, Airi Shibata, Rinka Ito, Ryo Kurasawa, Ryota Higuchi, Sungyeon Park, Hiroaki Niiro, Shinya Tanaka, Yoshihiro Baba
Abstract
Allogeneic islet transplantation is an effective treatment for type 1 diabetes, but its clinical use is limited by rejection involving innate and adaptive immune responses, requiring life-long immunosuppression. We herein engineered islets by transiently display two immunomodulators chimeric with streptavidin (SA), thrombomodulin (SA-TM) and CD47 (SA-CD47) for localized modulation of both innate and adaptive immune responses. The engineering process did not impact islet viability, glucose responsiveness, and metabolic activity. Intraportal transplantation into allogeneic recipients achieved sustained survival, with 8/11 grafts surviving 120-330 days without immunosuppression. In contrast, non-engineered islets were acutely rejected [median survival time (MST) = 12 days], while islets engineered with SA-TM showed delayed rejection [Median survival time (MST) = 13.5 days], and those with SA-CD47 exhibited prolonged survival (MST = 24 days). Double-engineered islets generated a localized tolerogenic immune environment characterized by low frequencies of inflammatory innate immune cells and increased frequencies of M2 macrophages, myeloid-derived suppressor cells, and CD4+FoxP3+ T regulatory cells. The transcriptomic analysis showed downregulation of proinflammatory and upregulation of immune regulatory pathways. Our results demonstrate that transient co-display of immunomodulatory molecules on the islet surface is a versatile platform with significant translational potential for islet transplantation.
Authors
Shadab Kazmi, Mohammad Tarique, Darshan Badal, Vahap Ulker, Ali Turan, Kathleen M. Yee-Flores, Abdalmonam Jadou Nejma, Esma S. Yolcu, Haval Shirwan
Abstract
Authors
Sebastian Kämpf, Marjan Hematianlarki, Leon Altmann, Jessica M. Bright, Alyssa M. A. Toda, Zohreh Mirzapoor, Valentin Zollner, Anja Werner, Johanna Bulang, Barbara Radovani, Miriam Wöhner, William Avery, Mark J. Karbarz, Pamela B. Conley, Greg P. Coffey, Falk Nimmerjahn
Abstract
Systemic sclerosis (SSc) is a complex and heterogeneous condition characterized by progressive fibrosis in multiple organs. Recent studies implicate plasminogen activator inhibitor 1 (PAI-1) in the pathogenesis of SSc, and PAI-1 is considered as a potential target for therapy. Here, using single-cell and spatial RNA-seq analysis of skin biopsies from 18 healthy individuals and 22 SSc patients, we found elevated PAI-1 co-localizing to myofibroblasts with enriched extracellular matrix-associated biological processes. Treatment of SSc dermal fibroblasts with the small molecule PAI-1 inhibitor MDI-2517 reduced the expression of the profibrotic markers COL1A1 and ACTA2. To investigate the therapeutic potential of MDI-2517, we evaluated its efficacy in reducing fibrosis in a preclinical model of SSc. Treatment of mice with MDI-2517 significantly reduced both skin and lung fibrosis and was superior to treatment with either pirfenidone or mycophenolate mofetil. Additionally, MDI-2517 attenuated weight loss and significantly reduced the expression of key profibrotic markers. Compared to tiplaxtinin, another PAI-1 inhibitor previously shown to be effective in a model of SSc, MDI-2517 was found to have superior efficacy at a 10-fold lower dose. These findings highlight the role of PAI-1 in the pathogenesis of SSc, and the potential of MDI-2517 for the treatment of SSc.
Authors
Enming J. Su, Pei-Suen Tsou, Mark Warnock, Natalya Subbotina, Kris Mann, Sirapa Vichaikul, Alyssa Rosek, Lisa Leung, Xianying Xing, Enze Xing, Olesya Plazyo, Rachael Bogle, Lam C. Tsoi, Cory D. Emal, Dinesh Khanna, John Varga, Thomas H. Sisson, Johann E. Gudjonsson, Daniel A. Lawrence
Abstract
Degradation of cellular waste from phagocytosis, endocytosis and autophagy occurs through hydrolases that become activated during acidification of late endosomes and lysosomes (LELs). In a cross-sectional study we show diminished LEL acidification and the accumulation of surface-bound nucleosome on monocytes, dendritic cells, and B cells from SLE patients. Diminished acidification and exocytosis of undegraded IgG-ICs is evident in active, but not inactive disease. This is supported by our murine study where LEL acidification is diminished, promoting exocytosis and the accumulation of cell surface IgG-immune complexes. Mechanistically, LEL dysfunction is induced by chronic PI3k activation in lupus-prone MRL/lpr mice. We also show that on a non-autoimmune C57BL/6 background, deficiency in SHP-1 and inhibition of SHIP-1 activity is sufficient to recapitulate LEL dysfunction found in MRL/lpr mice. Non-acidic LELs are evident in 67% of patients, and associate with SLEDAI arthritis, rash, and nephritis. The high frequency of LEL dysfunction in SLE suggests it could serve as a biomarker identifying a specific disease endotype.
Authors
SunAh Kang, Andrew J. Monteith, Liubov Arbeeva, Karissa Grier, Shruti Saxena Beem, Anthony C. Trujillo, Xinyun Bi, Kai Sun, Rebecca E. Sadun, Mithu Maheswaranathan, Megan E.B. Clowse, Saira Z. Sheikh, Jennifer L. Rogers, Barbara J. Vilen
Abstract
In pemphigus, autoantibodies against the desmosomal cadherins desmoglein (DSG) DSG1 and DSG3 cause intraepidermal blistering. Recently, we found that increasing cAMP with the phosphodiesterase-4 inhibitor apremilast stabilizes keratinocyte cohesion in pemphigus. This effect is paralleled by phosphorylation of the desmosomal plaque protein plakoglobin (PG) at serine 665 (S665). Here, we investigated the relevance of PG phosphorylation at S665 for stabilization of keratinocyte cohesion and further characterized the underlying mechanisms. Ultrastructural analysis of a recently established PG-S665 phospho-deficient mouse model (PG-S665A) showed diminished keratin insertion. Accordingly, the protective effect of apremilast against pemphigus autoantibody-induced skin blistering was diminished, and apremilast failed to restore alterations of the keratin cytoskeleton in PG-S665A mice. Keratinocytes derived from PG-S665A mice revealed a disorganized keratin cytoskeleton and reduced single-molecule binding strength of DSG3. In line with this, in ex vivo human skin, increased cAMP augmented keratin insertion into desmosomal plaques. Additionally, PG phosphorylated at S665 colocalized with desmoplakin and keratin filaments anchoring to desmosomes and increased cAMP-accelerated assembly of desmosomes. Taken together, phosphorylation of PG at S665 was crucial for protective effects of apremilast in pemphigus and for maintenance of DSG3 binding and keratin filament anchorage to desmosomes.
Authors
Franziska Vielmuth, Anna M. Sigmund, Desalegn T. Egu, Matthias Hiermaier, Letyfee S. Steinert, Sina Moztarzadeh, Mariia Klimkina, Margarethe E.C. Schikora, Paulina M. Rion, Thomas Schmitt, Katharina Meier, Kamran Ghoreschi, Anja K.E. Horn, Mariya Y. Radeva, Daniela Kugelmann, Jens Waschke
Abstract
Adaptive immune responses are widely considered the primary drivers of chronic inflammation in autoimmune disease, yet increasing evidence suggests that dysregulated myeloid cells play a central role in sustaining tissue damage. Salt-inducible kinases (SIKs) regulate immune cell activation, and their pharmacological inhibition can promote a shift from proinflammatory toward an immunoregulatory phenotype. We investigated whether selective inhibition of SIK2 and SIK3 with GLPG3970 could reprogram monocytes, macrophages, and dendritic cells, and we assessed pharmacological effects on activated T and B cells. Preclinical studies in mouse models of colitis, psoriasis, and arthritis demonstrated that SIK2/SIK3 inhibition reduced inflammatory activity and promoted immunoregulatory and tolerogenic-associated pathways. Clinical signal-detection studies in ulcerative colitis, psoriasis, and rheumatoid arthritis revealed signs of clinical and biological activity in ulcerative colitis and psoriasis. These findings suggest that myeloid cell dysfunction and impaired myeloid phenotype switching contribute to chronic inflammation in autoimmune diseases and that therapeutic targeting of SIK2/SIK3 holds the potential to restore immune balance by converting proinflammatory into regulatory pathways. Collectively, this work supports SIK2/SIK3 inhibition as a potential treatment strategy for myeloid cell–driven chronic inflammatory conditions.
Authors
Steve De Vos, Nicolas Desroy, Susan J. Bellaire, Anna Pereira Fernandes, Stéphanie Lavazais, Didier Merciris, Carole Delachaume, Catherine Robin-Jagerschmidt, Adrien Cosson, Angela Lazaryan, Nancy Van Osselaer, David Amantini, Christophe Peixoto, Maikel L. Colli, Thomas Van Eeckhoutte, Tiina Hakonen, Magali Constant, Alberto Garcia-Hernandez, Rahul Barron, Geert D’Haens, Wulf O. Böcher
Abstract
Systemic lupus erythematosus (SLE) is a chronic autoimmune disease characterized by immune dysregulation and widespread inflammation. Natural killer (NK) cells display marked functional impairment in SLE, including defective cytotoxicity and cytokine production, but the underlying mechanisms remain poorly defined. Here, we show that mitochondrial dysfunction and impaired mitophagy are key contributors to NK cell abnormalities in SLE. Using complementary structural, metabolic, and proteomic analyses, we found that SLE NK cells accumulate enlarged and dysfunctional mitochondria, exhibit impaired lysosomal acidification, and release mitochondrial DNA into the cytosol—features consistent with defective mitochondrial quality control. Transcriptional and proteomic profiling revealed downregulation of key mitophagy-related genes and pathways. These abnormalities correlated with reduced NK cell degranulation and cytokine production. We then tested whether enhancing mitochondrial quality control could restore NK cell function. The mitophagy activator Urolithin A improved mitochondrial and lysosomal parameters and rescued NK cell effector responses in vitro. Hydroxychloroquine partially restored mitochondrial recycling and reduced cytosolic mtDNA. These findings suggest that defective mitophagy and mitochondrial dysfunction are major contributors to NK cell impairment in SLE and that targeting mitochondrial quality control may represent a promising strategy for restoring immune balance in this disease.
Authors
Natalia W. Fluder, Morgane Humbel, Emeline Recazens, Alexis A. Jourdain, Camillo Ribi, George C. Tsokos, Denis Comte
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