B cell clonal expansion and cerebrospinal fluid (CSF) oligoclonal IgG bands are established features of the immune response in multiple sclerosis (MS). Clone-specific IgG1 monoclonal recombinant antibodies (rAbs) derived from MS patient CSF plasmablasts bound to conformational proteolipid protein 1 (PLP1) membrane complexes and, when injected into mouse brain with human complement, recapitulated histologic features of MS pathology: oligodendrocyte cell loss, complement deposition, and CD68+ phagocyte infiltration. Conformational PLP1 membrane epitopes were complex and governed by the local cholesterol and glycolipid microenvironment. Antibodies against conformational PLP1 membrane complexes targeted multiple surface epitopes, were enriched within the CSF compartment, and were detected in most MS patients but not in inflammatory and non-inflammatory neurologic controls. CSF PLP1 complex antibodies provide a pathogenic autoantibody biomarker specific for MS.
Gregory P. Owens, Timothy J. Fellin, Adeline Matschulat, Vanessa Salas, Kristin L. Schaller, Katherine S. Given, Alanna M. Ritchie, Andre Navarro, Kevin Blauth, Ethan G. Hughes, Wendy B. Macklin, Jeffrey L. Bennett
Adoptive immunotherapy with Tregs is a promising approach for prevention or treatment of type 1 diabetes. Islet antigen-specific Tregs have more potent therapeutic effects than polyclonal cells, but their low frequency is a barrier for clinical application. To generate Tregs that recognize islet antigens, we engineered a chimeric antigen receptor (CAR) derived from a monoclonal antibody with specificity for the insulin B-chain 10-23 peptide presented in the context of the IAg7 MHC class II allele present in NOD mice. Peptide specificity of the resulting InsB-g7 CAR was confirmed by tetramer staining and T cell proliferation in response to recombinant or islet-derived peptide. The InsB-g7 CAR re-directed NOD Treg specificity such that insulin B 10-23-peptide stimulation enhanced suppressive function, measured via reduction of proliferation and IL-2 production by BDC2.5 T cells and CD80 and CD86 expression on dendritic cells. Co-transfer of InsB-g7 CAR Tregs prevented adoptive transfer diabetes by BDC2.5 T cells in immunodeficient NOD mice. In wild type NOD mice, InsB-g7 CAR Tregs prevented spontaneous diabetes. These results show that engineering Treg specificity for islet antigens using a T cell receptor-like CAR is a promising new therapeutic approach for the prevention of autoimmune diabetes.
Justin A. Spanier, Vivian Fung, Christine M. Wardell, Mohannad H. Alkhatib, Yixin Chen, Linnea A. Swanson, Alexander J. Dwyer, Matthew E. Weno, Nubia Silva, Jason S. Mitchell, Paul C. Orban, Majid Mojibian, C. Bruce Verchere, Brian T. Fife, Megan K. Levings
BACKGROUND. Autoimmune diseases often have strong genetic associations with specific HLA-DR alleles. The synovial lesion in chronic inflammatory forms of arthritis shows marked up-regulation of HLA-DR molecules, including in post-infectious Lyme arthritis (LA). However, the identity of HLA-DR-presented peptides and therefore, the reasons for these associations have frequently remained elusive. METHODS. Using immunopeptidomics to detect HLA-DR-presented peptides from synovial tissue, we identified T cell epitopes from 3 extracellular matrix (ECM) proteins in patients with post-infectious LA, identified potential Borreliella burgdorferi (Bb)-mimic epitopes, and characterized T and B cell responses to these peptides or proteins. RESULTS. Of 24 post-infectious LA patients, 58% had CD4+ T cell responses to ≥1 epitope of 3 ECM proteins, fibronectin-1, laminin B2, and/or collagen Vα1, and 17% of 52 such patients had antibody responses to >1 of these proteins. Patients with autoreactive T cell responses had significantly increased frequencies of HLA-DRB1*04 or DRB1*1501 alleles and more prolonged arthritis. When tetramer reagents were loaded with ECM or corresponding Bb-mimic peptides, binding was only with the autoreactive T cells. A high percentage of ECM-autoreactive CD4+ T cells in synovial fluid were T-bet-expressing Th1 cells, a small percentage were RoRyt-expressing Th17 cells, and a minimal percentage were FoxP3-expressing Treg cells. CONCLUSION. Autoreactive, proinflammatory CD4+ T cells and autoantibodies develop to ECM proteins in a subgroup of post-infectious LA patients who have specific HLA-DR alleles. Rather than the traditional molecular mimicry model, we propose that epitope spreading provides the best explanation for this example of infection-induced autoimmunity.
Korawit Kanjana, Klemen Strle, Robert B. Lochhead, Annalisa Pianta, Laura M. Mateyka, Qi Wang, Sheila L. Arvikar, David E. Kling, Cameron A. DeAngelo, Lucy Curham, Alan G. Barbour, Catherine E. Costello, James J. Moon, Allen C. Steere
Multiple Sclerosis (MS) is a complex disease of the CNS thought to require an environmental trigger. Gut dysbiosis is common in MS, but specifically causative species are unknown. To address this knowledge gap, we used sensitive and quantitative PCR detection to show that people with MS were more likely to harbor and show a greater abundance of epsilon toxin (ETX)-producing strains of C. perfringens within their gut microbiomes compared to healthy controls (HC). MS patient-derived isolates produced functional ETX and had a genetic architecture typical of highly conjugative plasmids. In the active immunization model of experimental autoimmune encephalomyelitis (EAE), where pertussis toxin (PTX) is used to overcome CNS immune privilege, ETX can substitute for PTX. In contrast to PTX-induced EAE, where inflammatory demyelination is largely restricted to the spinal cord, ETX-induced EAE caused demyelination in the corpus callosum, thalamus, cerebellum, brainstem, and spinal cord, more akin to the neuroanatomical lesion distribution in MS. CNS endothelial cell transcriptional profiles revealed ETX-induced genes that are known to play a role in overcoming CNS immune privilege. Together, these findings suggest that ETX-producing C. perfringens strains are biologically plausible pathogens in MS that trigger inflammatory demyelination in the context of circulating myelin autoreactive lymphocytes.
Yinghua Ma, David Sannino, Jennifer R. Linden, Sylvia Haigh, Baohua Zhao, John B. Grigg, Paul Zumbo, Friederike Dündar, Daniel J. Butler, Caterina P. Profaci, Kiel M. Telesford, Paige N. Winokur, Kareem R. Rumah, Susan A. Gauthier, Vincent A. Fischetti, Bruce A. McClane, Francisco A. Uzal, Lily Zexter, Michael Mazzucco, Richard Rudick, David Danko, Evan Balmuth, Nancy Nealon, Jai Perumal, Ulrike W. Kaunzner, Ilana L. Brito, Zhengming Chen, Jenny Z. Xiang, Doron Betel, Richard Daneman, Gregory F. Sonnenberg, Christopher E. Mason, Timothy Vartanian
Signaling driven by nucleic acid sensors participates in interferonopathy-mediated autoimmune diseases. NLRP12, a pyrin-containing NLR protein, is a negative regulator of innate immune activation and type I interferon (IFN-I) production. Peripheral blood mononuclear cells (PBMCs) derived from systemic lupus erythematosus (SLE) patients expressed lower levels of NLRP12, with an inverse correlation with IFNA expression and high disease activity. NLRP12 expression was transcriptionally suppressed by runt-related transcription factor 1–dependent (RUNX1-dependent) epigenetic regulation under IFN-I treatment, which enhanced a negative feedback loop between low NLRP12 expression and IFN-I production. Reduced NLRP12 protein levels in SLE monocytes was linked to spontaneous activation of innate immune signaling and hyperresponsiveness to nucleic acid stimulations. Pristane-treated Nlrp12–/– mice exhibited augmented inflammation and immune responses; and substantial lymphoid hypertrophy was characterized in NLRP12-deficient lupus-prone mice. NLRP12 deficiency mediated the increase of autoantibody production, intensive glomerular IgG deposition, monocyte recruitment, and the deterioration of kidney function. These were bound in an IFN-I signature–dependent manner in the mouse models. Collectively, we reveal a remarkable link between low NLRP12 expression and lupus progression, which suggests the impact of NLRP12 on homeostasis and immune resilience.
Yen-Po Tsao, Fang-Yu Tseng, Chih-Wei Chao, Ming-Han Chen, Yi-Chen Yeh, Babamale Olarewaju Abdulkareem, Se-Yi Chen, Wen-Ting Chuang, Pei-Ching Chang, I-Chun Chen, Pin-Hsuan Wang, Chien-Sheng Wu, Chang-Youh Tsai, Szu-Ting Chen
B cell depletion in patients with relapsing-remitting multiple sclerosis (RRMS) markedly prevents new MRI-detected lesions and disease activity, suggesting the hypothesis that altered B cell function leads to the activation of T cells driving disease pathogenesis. Here, we performed comprehensive analyses of CD40 ligand– (CD40L-) and IL-21–stimulated memory B cells from patients with MS and healthy age-matched controls, modeling the help of follicular helper T cells (Tfh cells), and found a differential gene expression signature in multiple B cell pathways. Most striking was the impaired TIGIT expression on MS-derived B cells mediated by dysregulation of the transcription factor TCF4. Activated circulating Tfh cells (cTfh cells) expressed CD155, the ligand of TIGIT, and TIGIT on B cells revealed their capacity to suppress the proliferation of IL-17–producing cTfh cells via the TIGIT/CD155 axis. Finally, CCR6+ cTfh cells were significantly increased in patients with MS, and their frequency was inversely correlated with that of TIGIT+ B cells. Together, these data suggest that the dysregulation of negative feedback loops between TIGIT+ memory B cells and cTfh cells in MS drives the activated immune system in this disease.
Hiromitsu Asashima, Pierre-Paul Axisa, Thi Hong Giang Pham, Erin E. Longbrake, William E. Ruff, Nikhil Lele, Inessa Cohen, Khadir Raddassi, Tomokazu S. Sumida, David A. Hafler
Astrocytes are highly heterogenic in their phenotype and function, which contribute to CNS disease, repair and aging; however, the molecular mechanism of their functional states remains largely unknown. Here we show that activation of sirtuin 1 (SIRT1), a protein deacetylase, plays an important role in the detrimental actions of reactive astrocytes, whereas its inactivation endorsed these cells with anti-inflammatory functions that inhibited the production of proinflammatory mediators by myeloid cells/microglia and promoted the differentiation of oligodendrocyte progenitor cells. Mice with astrocyte-specific Sirt1 knockout had suppressed progression of experimental autoimmune encephalomyelitis (EAE), an animal model of CNS inflammatory demyelinating diseases. Ongoing EAE was also suppressed when Sirt1 expression in astrocytes was diminished by CRISPR/Cas vector, resulting in reduced demyelination, decreased numbers of T cells, and increased rate of IL-10-producing macrophages/microglia in the CNS, whereas peripheral immune response remained unaffected. Mechanistically, Sirt1-/- astrocytes expressed a range of nuclear factor erythroid-derived 2-like 2 (Nfe2l2) target genes, and Nfe2l2 deficiency shifted the beneficial action of Sirt1-/- astrocytes to a detrimental one. These findings identify a novel approach for switching functional state of reactive astrocytes and facilitate the development of astrocyte-targeting therapies for inflammatory neurodegenerative diseases such as multiple sclerosis.
Weifeng Zhang, Dan Xiao, Xing Li, Yuan Zhang, Javad Rasouli, Giacomo Casella, Alexandra Boehm, Daniel Hwang, Larissa L.W. Ishikawa, Rodolfo Thome, Bogoljub Ciric, Mark T. Curtis, Abdolmohamad Rostami, Guang-Xian Zhang
BACKGROUND. Anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitidies (AAV) are life-threatening systemic autoimmune conditions. ANCA directed against proteinase 3 (PR3) or myeloperoxidase (MPO) bind their cell surface-presented antigen, activate neutrophils and cause vasculitis. An imbalance between PR3 and its major inhibitor α1-antitrypsin (AAT) was proposed to underlie PR3- but not MPO-AAV. We measured AAT and PR3 in healthies and AAV patients and studied protective AAT effects pertaining to PR3- and MPO-ANCA. METHODS. Plasma and blood neutrophils were assessed for PR3 and AAT. Wild-type, mutant, and oxidation-resistant AAT species were produced to characterize AAT-PR3 interactions by flow cytometry, immunoblotting, FRET assays, and surface plasmon resonance measurements. Neutrophil activation was measured using the ferricytochrome C assay and AAT methionine-oxidation by Parallel Reaction Monitoring. RESULTS. We found significantly increased PR3 and AAT pools in both PR3- and MPO-AAV patients, however, only in PR3-AAV did the PR3 pool correlate with ANCA titer, inflammatory response and disease severity. Mechanistically, AAT prevented PR3 from binding to CD177, thereby reducing neutrophil surface antigen for ligation by PR3-ANCA. Active PR3-AAV patients showed critical methionine-oxidation in plasma AAT that was recapitulated by ANCA-activated neutrophils. The protective PR3-related AAT effects were compromised by methionine-oxidation in the AAT reactive center loop but preserved when two critical methionines were substituted by valine and leucine. CONCLUSION. Pathogenic differences between PR3- and MPO-AAV are related to AAT regulation of membrane-PR3, attenuating neutrophil activation by PR3- rather than MPO-ANCA. Oxidation-resistant AAT could serve as adjunctive therapy in PR3-AAV.
Maximilian J.P. Ebert, Uwe Jerke, Claudia Eulenberg-Gustavus, Lovis Kling, Dieter E. Jenne, Marieluise Kirchner, Philipp Mertins, Markus Bieringer, Saban Elitok, Kai-Uwe Eckardt, Adrian Schreiber, Alan D. Salama, Ralph Kettritz
FcɣRIIB is an inhibitory receptor expressed throughout B cell development. Diminished expression or function is associated with lupus in mice and humans, in particular through an effect on autoantibody production and plasma cell differentiation. Here, we analysed the effect of B cell-intrinsic FcɣRIIB expression on B cell activation and plasma cell differentiation. Loss of FcɣRIIB on B cells (Fcgr2b cKO mice) led to a spontaneous increase in autoantibody titers. This increase was most striking for IgG3, suggestive of increased extrafollicular responses. Marginal zone (MZ) B cells had the highest expression of FcɣRIIB in both mouse and human. This high expression of FcɣRIIB was linked to increased MZ B cell activation, Erk phosphorylation, and calcium fluxin the absence of FcɣRIIB triggering. Marked increases in IgG3+ plasma cells and B cells were observed during extrafollicular plasma cell responses in Fcgr2b cKO mice. The increased IgG3 response following immunization of Fcgr2b cKO mice was lost in MZ-deficient Notch2/Fcgr2b cKO mice. Importantly, SLE patients exhibited decreased expression of FcɣRIIB, most strongly in MZ B cells. Thus, we present a model where high FcɣRIIB expression in MZ B cells prevents their hyperactivation and ensuing autoimmunity.
Ashley N. Barlev, Susan Malkiel, Izumi Kurata-Sato, Annemarie L. Dorjée, Jolien Suurmond, Betty Diamond
Plasmacytoid dendritic cell (pDC) is a professional type I interferon producer, which plays critical roles in the pathogenesis of autoimmune diseases. However, both genetic regulation of pDC function and their relationships with autoimmunity are largely undetermined. Here, we investigated the causality of NCF1 missense variant, which is one of the most significant associated risk variants for lupus, and found that the substitution from arginine (R) to histidine (H) at position 90 in NCF1 protein (NCF1 p.R90H) led to excessive activation of pDCs. Mechanism study demonstrated that p.R90H reduced the affinity of NCF1 to phospholipid, thereby impaired endosomal localization of NCF1. As NCF1 is a subunit of NOX2 complex, this impairment led to acidified endosomal pH and facilitated downstream TLR signaling. Consistently, the homozygous knock-in mice manifested aggravated lupus progression in a pDC dependent lupus model. More importantly, pharmaceutical intervention revealed that hydroxychloroquine (HCQ) could antagonize the detrimental function of NCF1 p.R90H in lupus model and systemic lupus erythematosus (SLE) samples, supporting that NCF1 p.R90H could be identified as a genetic biomarker for HCQ application. Therefore, our study provides insights into the genetic control of pDC function and paradigm for applying genetic variants to improve targeted therapy for autoimmune diseases.
Yao Meng, Jianyang Ma, Chao Yao, Zhizhong Ye, Huihua Ding, Can Liu, Jun Li, Guanhua Li, Yuke He, Jia Li, Zhihua Yin, Li Wu, Haibo Zhou, Nan Shen
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