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The management of autoimmune diseases is currently limited by therapies that largely suppress the immune system, often resulting in partial and temporary remissions. Cellular immunotherapies offer a targeted approach by redirecting immune cells to correct the underlying autoimmunity. This review explores the latest advances in cellular immunotherapies for autoimmune diseases, focusing on various strategies, such as the use of chimeric antigen receptor (CAR) T cells, chimeric auto-antibody receptor (CAAR) T cells, regulatory T cells (Tregs), and tolerogenic dendritic cells (TolDCs). We review recent preclinical studies and results from clinical trials that demonstrate the potential for these therapies to either deplete autoreactive cells or promote immune tolerance through broad or selective targeting of immune cell populations. Key challenges such as ensuring specificity, preventing off-target effects, and improving the longevity of therapeutic effects are discussed. The evolving landscape of cellular immunotherapies holds promise for more durable treatment responses and increased specificity for autoimmune disease treatment., Competing Interests: Declarations. Conflict of interest: All other authors declare no conflict of interest., (© 2025. The Author(s).)

Early expansion and long-term persistence predict efficacy of chimeric antigen receptor T cells (CARTs) 1-7 , but mechanisms governing effector versus memory CART differentiation and whether asymmetric cell division induces differential fates in human CARTs remain unclear. Here we show that target-induced proximity labelling enables isolation of first-division proximal-daughter and distal-daughter CD8 CARTs that asymmetrically distribute their surface proteome and transcriptome, resulting in divergent fates. Target-engaged CARs remain on proximal daughters, which inherit a surface proteome resembling activated-undivided CARTs, whereas the endogenous T cell receptor and CD8 enrich on distal daughters, whose surface proteome resembles resting CARTs, correlating with glycolytic and oxidative metabolism, respectively. Despite memory-precursor phenotype and in vivo longevity, distal daughters demonstrate transient potent cytolytic activity similar to proximal daughters, uncovering an effector-like state in distal daughters destined to become memory CARTs. Both partitioning of pre-existing transcripts and changes in RNA velocity contribute to asymmetry of fate-determining factors, resulting in diametrically opposed transcriptional trajectories. Independent of naive, memory or effector surface immunophenotype, proximal-daughter CARTs use core sets of transcription factors known to support proliferation and effector function. Conversely, transcription factors enriched in distal daughters restrain differentiation and promote longevity, evidenced by diminished long-term in vivo persistence and function of distal-daughter CARTs after IKZF1 disruption. These studies establish asymmetric cell division as a framework for understanding mechanisms of CART differentiation and improving therapeutic outcomes., (© 2024. The Author(s).)

Background: For psoriatic patients who need to receive nonlive or live vaccines, evidence-based recommendations are needed regarding whether to pause or continue systemic therapies for psoriasis and/or psoriatic arthritis., Objective: To evaluate literature regarding vaccine efficacy and safety and to generate consensus-based recommendations for adults receiving systemic therapies for psoriasis and/or psoriatic arthritis receiving nonlive or live vaccines., Methods: Using a modified Delphi process, 22 consensus statements were developed by the National Psoriasis Foundation Medical Board and COVID-19 Task Force, and infectious disease experts., Results: Key recommendations include continuing most oral and biologic therapies without modification for patients receiving nonlive vaccines; consider interruption of methotrexate for nonlive vaccines. For patients receiving live vaccines, discontinue most oral and biologic medications before and after administration of live vaccine. Specific recommendations include discontinuing most biologic therapies, except for abatacept, for 2-3 half-lives before live vaccine administration and deferring next dose 2-4 weeks after live vaccination., Limitations: Studies regarding infection rates after vaccination are lacking., Conclusion: Interruption of antipsoriatic oral and biologic therapies is generally not necessary for patients receiving nonlive vaccines. Temporary interruption of oral and biologic therapies before and after administration of live vaccines is recommended in most cases., Competing Interests: Conflicts of interest Dr Chat, Dr Ellebrecht, Ms. Kingston, and Dr Cordoro have no conflicts of interest to declare. Dr Bell is an employee of the National Psoriasis Foundation. Author Gondo is an employee of the National Psoriasis Foundation. Dr Desai has served as a research investigator, consultant, speaker, and/or advisor for AbbVie, Galderma, Foundation for Research & Education of Dermatology, Almirall, Dermavant, Ferndale Laboratories, Inc, Incyte Corporation, Gore Range Capital, AOBiome, LLC, Bristol Myers Squibb, Verrica Pharmaceuticals, UCB, Ortho Dermatologics, Scientis, EPI Health, Avita, Pfizer, Lilly, LEO, Incyte Corporation, L'Oreal USA, Inc, Beiersdorf, Inc, and Johnson and Johnson; is a board member of the National Psoriasis Foundation and Women's Derm Society; and is a stockholder for Gore Range Capital. Dr Duffin has been a consultant, advisor, or served as an investigator for AbbVie, AnaptysBio, Amgen, Bristol-Myers Squib, Celgene, CorEvitas/Corrona, Boehringer-Ingelheim, Janssen, Lilly, Novartis, Ortho Dermatologica, Pfizer, Regeneron, Sienna, Stiefel, and UCB. Dr Feldman has received research, speaking and/or consulting support from Eli Lilly and Company, GlaxoSmithKline/Stiefel, AbbVie, Janssen, Alovtech, vTv Therapeutics, Bristol-Myers Squibb, Samsung, Pfizer, Boehringer Ingelheim, Amgen Inc, Dermavant, Arcutis, Novartis, Novan, UCB, Helsinn, SunPharma, Almirall, Galderma, Leo Pharma, Mylan, Celgene, Valeant, Menlo, Merck & Co, Qurient Forte, Arena, Biocon, Accordant, Argenx, Sanofi, Regeneron, the National Biological Corporation, Caremark, Advance Medical, Suncare Research, Informa, UpToDate and the National Psoriasis Foundation; is the founder and majority owner of www.DrScore.com; is a founder and part owner of Causa Research; and has stock in Sensal Health. Dr Garg is an advisor for AbbVie, Aclaris Therapeutics, Anaptys Bio, Aristea Therapeutics, Boehringer Ingelheim, Bristol Myers Squibb, Incyte, InflaRx, Insmed, Janssen, Novartis, Pfizer, UCB, and Viela Biosciences; receives honoraria; and receives research grants from AbbVie, UCB and National Psoriasis Foundation. Dr Gelfand served as a consultant for Abbvie, BMS, Boehringer Ingelheim, Celldex (DSMB), FIDE (which is sponsored by multiple pharmaceutical companies) GSK, Happify, Lilly (DMC), Leo, Janssen Biologics, Neumentum, Novartis Corp, Pfizer, UCB (DSMB), Neuroderm (DSMB), Regeneron, Trevi, and Mindera Dx., receiving honoraria; receives research grants (to the Trustees of the University of Pennsylvania) from Boehringer Ingelheim, and Pfizer Inc; and received payment for continuing medical education work related to psoriasis that was supported indirectly pharmaceutical sponsors. Dr Gelfand is a co-patent holder of resiquimod for treatment of cutaneous T cell lymphoma. Dr Gelfand is a Deputy Editor for the Journal of Investigative Dermatology receiving honoraria from the Society for Investigative Dermatology, is Chief Medical Editor for Healio Psoriatic Disease (receiving honoraria) and is a member of the Board of Directors for the International Psoriasis Council, receiving no honoraria. Dr Gladman has served as a consultant for AbbVie, Amgen, BMS, Eli Lily, Galapagos, Gilead, Janssen, Novartis, Pfizer, and UCB; and has received grants from AbbVie, Amgen, Eli Lily, Janssen, Novartis, Pfizer, and UCB. Dr Green is a research investigator, speaker, and/or consultant for AbbVie, Amgen, Arcutis, BMS, Dermavant, Lilly, MC2, SunPharma, and UCB. Dr Gudjonsson has served as an advisor for Novartis, Janssen, Almirall, Eli Lilly, Sanofi, and Boehringer Ingelheim; and has received research support from Almirall, Eli Lilly, Prometheus, BMS, and Janssen. Dr Han has served as a research investigator, consultant, and/or speaker for AbbVie, Amgen, Boehringer Ingelheim, BMS, Dermavant, Janssen, Lilly, UCB, Novartis, Leo Pharma, Regeneron, Sanofi Genzyme, Ortho Dermatologics, Bond Avillion, Pellepharm, MC2, Athenex, Celgene, Sun Pharma, and Pfizer. Dr Hawkes is an advisor and/or consultant for AbbVie, Arcutis, Boehringer Ingelheim, Janssen, LearnSkin, LEO, Lilly, Novartis, Pfizer, Regeneron-Sanofi Genzyme, and UCB; is a board member of the National Psoriasis Foundation; and has stock ownership/equity of Regeneron Pharmaceuticals. Dr Kircik is a research investigator, speaker, advisor, and/or consultant for Abbott Laboratories, Allergan, Almirall, Amgen, Arcutis, Biogen-Idec, BMS, Boehringer-Ingleheim, Breckinridge Pharma, Celgene, Centocor, Inc, Cellceutix, Cipher, Combinatrix, Connetics Corporation, Coria, Dermavant, Dermira, Dow Pharmaceutical Sciences, Inc, Dr Reddy's Lab, Eli Lilly, Galderma, Genentech, Inc, GlaxoSmithKline, PLC, Idera, Leo, Maruho, Merck, Medicis Pharmaceutical Corp., Novartis AG, Promius, PharmaDerm, Pfizer, Serono, Stiefel Laboratories, Inc, Sun Pharma, Taro, UCB, Valeant Pharmaceuticals Intl, and XenoPort. Dr Koo is a speaker and/or advisor for AbbVie, Amgen, Lilly, UCB, Ortho Dermatologics, LEO, Sun Pharma, Janssen, and Epi Pharm. Dr Langley has been an investigator, served on the scientific advisory board, and/or has provided a lecture for AbbVie, Amgen, Boehringer Ingelheim, Celgene, Leo, Lilly, Merck, Novartis, Pfizer, and UCB. Dr Lebwohl is an employee of Mount Sinai; receives research funds from AbbVie, Amgen, Arcutis, Avotres, Boehringer Ingelheim, Cara Therapeutics, Dermavant Sciences, Eli Lilly, Incyte, Janssen Research & Development, LLC, Ortho Dermatologics, Regeneron, and UCB, Inc; and is a consultant for Aditum Bio, Almirall, AltruBio Inc, AnaptysBio, Arcutis, Inc, Arena Pharmaceuticals, Aristea Therapeutics, Arrive Technologies, Avotres Therapeutics, BiomX, Brickell Biotech, Boehringer-Ingelheim, Bristol Myers Squibb, Cara Therapeutics, Castle Biosciences, Corevitas, Dermavant Sciences, Dr Reddy's Laboratories, Evelo Biosciences, Evommune, Inc, Facilitatation of International Dermatology Education, Forte Biosciences, Foundation for Research and Education in Dermatology, Helsinn Therapeutics, Hexima Ltd., LEO Pharma, Meiji Seika Pharma, Mindera, Pfizer, Seanergy, and Verrica. Dr Lewitt has received speaking and/or consulting support from AbbVie, Lilly, Janssen, Ortho Dermatologics, UCB, Galderma, Pfizer; received honoraria; and served as an advisor for AbbVie, Janssen, and Dermavant. Dr Liao has received research/grant support from AbbVie, Amgen, Janssen, Leo, Novartis, Trex Bio, Pfizer, and Regeneron. Dr Martin has served as an advisor for Bristol Meyers Squibb, DUSA/SUN, AbbVie, Ortho/Bausch Health, Galderma, Pfizer, LEO, Janssen, Horizon, UCB, Trevi, Almirall, Dermavent, Incyte, and Lilly; has served as a consultant for Bristol Meyers Squibb, DUSA/SUN, AbbVie, Ortho/Bausch Health, Galderma, Pfizer, LEO, UCB, Trevi, Almirall, Lilly, Arcutis, and Dermavant; and has received speaking support from UCB, Almirall, LEO, Incyte, Dermavant, and Bristol Meyers Squibb. Dr Orbai is a consultant and/or advisor for Janssen, Novartis, and UCB; and receives research support from AbbVie, Amgen, and Celgene. Dr Reddy has served as a consultant for Novartis, AbbVie, Janssen, and UCB; and has received grant support from Pfizer. Ms Richardson has served as an advisor for and received honoraria from Boehringer Engelheim and Lilly. Dr Ritchlin is a consultant and/or speaker for Novartis, Lilly, AbbVie, Janssen, UCB, and Pfizer. Dr Schwartzman has received speaking support from AbbVie, Janssen, Lilly, Pfizer, Novartis, and UCB; served as a consultant for Abbvie, Janssen, Lilly, Myriad, Novartis, Regeneron, Sanofi, UCB, Stelexis, Jubilant, and Teijin; is a board member of the National Psoriasis Foundation; and served as an advisor for Myriad. Dr Siegel has served as an advisor, speaker, and/or consultant for Abbvie, UCB, Lilly, Horizon, and BMS. Dr Van Voorhees has served as a research investigator and/or scientific advisor for Lilly, AbbVie, UCB, Bristol Meyers Squibb, Amgen, Boehringer Ingelheim, Novartis, and Merck. Dr Wallace serves as an investigator for Pfizer and Target RWE. Dr Weinberg is a research investigator, consultant, and/or speaker for Novartis, Lilly, Amgen, AbbVie, Sun, Janssen, and BMS. Dr Winthrop is a consultant for Pfizer, AbbVie, Union Chimique Belge (UCB), Eli Lilly & Company, Galapagos, GlaxoSmithKline (GSK), Roche, Gilead, Bristol Myers Squibb (BMS), Regeneron, Sanofi, AstraZeneca, and Novartis; and receives research funding from BMS and Pfizer. Dr Yamauchi serves as a research investigator, consultant, and speaker for Abbvie, Amgen, BMS, Janssen, Lilly, Novartis, Pfizer, Sun Pharma, UCB. Dr Armstrong has served as a research investigator, scientific advisor, and/or speaker to AbbVie, Almirall, Arcutis, ASLAN, Beiersdorf, BI, BMS, EPI, Incyte, Leo, UCB, Janssen, Lilly, Mindera, Nimbus, Novartis, Ortho Dermatologics, Sun, Dermavant, Dermira, Sanofi, Regeneron, and Pfizer., (Copyright © 2024. Published by Elsevier Inc.)

Muscle-specific tyrosine kinase myasthenia gravis (MuSK MG) is an autoimmune disease that causes life-threatening muscle weakness due to anti-MuSK autoantibodies that disrupt neuromuscular junction signaling. To avoid chronic immunosuppression from current therapies, we engineered T cells to express a MuSK chimeric autoantibody receptor with CD137-CD3ζ signaling domains (MuSK-CAART) for precision targeting of B cells expressing anti-MuSK autoantibodies. MuSK-CAART demonstrated similar efficacy as anti-CD19 chimeric antigen receptor T cells for depletion of anti-MuSK B cells and retained cytolytic activity in the presence of soluble anti-MuSK antibodies. In an experimental autoimmune MG mouse model, MuSK-CAART reduced anti-MuSK IgG without decreasing B cells or total IgG levels, reflecting MuSK-specific B cell depletion. Specific off-target interactions of MuSK-CAART were not identified in vivo, in primary human cell screens or by high-throughput human membrane proteome array. These data contributed to an investigational new drug application and phase 1 clinical study design for MuSK-CAART for the treatment of MuSK autoantibody-positive MG., (© 2023. The Author(s).)

Background: Programmed cell death protein (PD-1) and programmed death-ligand 1 (PD-L1) inhibition checkpoint blockade leads to various cutaneous adverse reactions, including bullous pemphigoid and lichen-planus-like reactions. However, lichen planus pemphigoides (LPP), manifesting histopathologic features of both lichen planus and bullous pemphigoid, has more rarely been associated with immunotherapy., Methods: The clinical and histopathologic findings of three patients were examined, and a review of cases of LPP and bullous lichen planus secondary to PD-1 inhibitor therapy was performed., Results: Three patients (two with advanced non-small-cell lung adenocarcinoma and the third with metastatic breast cancer) presented with both lichenoid eruptions and bullae. Biopsy of the lesions revealed lichenoid tissue reactions in all three patients. Together with the histopathologic findings, direct immunofluorescence (DIF) showing linear C3 and IgG deposition and positive enzyme-linked immunosorbent assay (ELISA) showing BP180 positivity supported a diagnosis of LPP in two patients. The third patient in our series also showed confirmatory ELISA testing supporting LPP., Conclusions: Lichen planus pemphigoides is a distinct cutaneous toxicity to checkpoint inhibitor therapy illustrates a possible pathogenic mechanism and the importance of dermatopathology recognition to render an accurate diagnosis., (© 2022 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Pemphigus and pemphigoid are paradigms for understanding the mechanisms of antibody-mediated autoimmune disease in humans. In pemphigus, IgG4-predominant autoantibodies cause intraepidermal blistering by direct interference with desmoglein interactions and subsequent disruption of desmosomes and signaling pathways. In pemphigoid, IgG1, IgG4, and IgE autoantibodies against basement membrane zone antigens directly interfere with hemidesmosomal adhesion, activating complement and Fc receptor‒mediated effector pathways. Unraveling disease mechanisms in pemphigus and pemphigoid has identified numerous opportunities for clinical trials, which hold promise to identify safer and more effective therapies for these potentially life-threatening diseases., (Copyright © 2021 The Authors. Published by Elsevier Inc. All rights reserved.)

Follicular T helper cells (Tfh) are a specialized subset of CD4 effector T cells that are crucial for germinal center (GC) reactions and for selecting B cells to undergo affinity maturation. Despite this central role for humoral immunity, only few data exist about their clonal distribution when multiple lymphoid organs are exposed to the same antigen (Ag) as it is the case in autoimmunity. Here, we used an autoantibody-mediated disease model of the skin and injected one auto-Ag into the two footpads of the same mouse and analyzed the T cell receptor (TCR)β sequences of Tfh located in GCs of both contralateral draining lymph nodes. We found that over 90% of the dominant GC-Tfh clonotypes were shared in both lymph nodes but only transiently. The initially dominant Tfh clonotypes especially declined after establishment of chronic disease while GC reaction and autoimmune disease continued. Our data demonstrates a dynamic behavior of Tfh clonotypes under autoimmune conditions and emphasizes the importance of the time point for distinguishing auto-Ag-specific Tfh clonotypes from potential bystander activated ones., Competing Interests: MN, JB, AF, AS, MI, CE, CH, KB, JW, KK No competing interests declared, (© 2021, Niebuhr et al.)

Objective: To update guidance regarding the management of psoriatic disease during the COVID-19 pandemic., Study Design: The task force (TF) includes 18 physician voting members with expertise in dermatology, rheumatology, epidemiology, infectious diseases, and critical care. The TF was supplemented by nonvoting members, which included fellows and National Psoriasis Foundation staff. Clinical questions relevant to the psoriatic disease community were informed by inquiries received by the National Psoriasis Foundation. A Delphi process was conducted., Results: The TF updated evidence for the original 22 statements and added 5 new recommendations. The average of the votes was within the category of agreement for all statements, 13 with high consensus and 14 with moderate consensus., Limitations: The evidence behind many guidance statements is variable in quality and/or quantity., Conclusions: These statements provide guidance for the treatment of patients with psoriatic disease on topics including how the disease and its treatments affect COVID-19 risk, how medical care can be optimized during the pandemic, what patients should do to lower their risk of getting infected with severe acute respiratory syndrome coronavirus 2 (including novel vaccination), and what they should do if they develop COVID-19. The guidance is a living document that is continuously updated by the TF as data emerge., Competing Interests: Conflicts of interest Dr Gelfand has served as a consultant for Bristol Myers Squibb, Boehringer Ingelheim, GlaxoSmithKline, Janssen Biologics, Novartis Corp, Regeneron, UCB (Data Safety and Monitoring Board), Sanofi, and Pfizer, receiving honoraria; has received research grants (to the Trustees of the University of Pennsylvania) from AbbVie, Janssen, Novartis Corp, Sanofi, Celgene, OrthoDermatologics, and Pfizer; has received payment for continuing medical education work related to psoriasis that was supported indirectly by Eli Lilly and Company and Ortho Dermatologics; is a copatent holder of resiquimod for treatment of cutaneous T-cell lymphoma; and is a deputy editor for the Journal of Investigative Dermatology, receiving honoraria from the Society for Investigative Dermatology. Dr Armstrong has served as a research investigator and/or scientific advisor to Leo, AbbVie, UCB, Incyte, Janssen, Lilly, Novartis, Ortho Dermatologics, Sun, Dermavant, Bristol Myers Squibb, Sanofi, Regeneron, Dermira, and Modmed. Dr Bell is an employee of the National Psoriasis Foundation. Dr Anesi is supported by the Agency for Healthcare Research and Quality (K12HS026372) and has received fees from UpToDate for authoring COVID-19 clinical reference material. Dr Blauvelt has served as a scientific advisor and/or clinical study investigator for AbbVie, Almirall, Arena, Athenex, Boehringer Ingelheim, Bristol Myers Squibb, Dermavant, Eli Lilly and Company, Evommune, Forte, Galderma, Incyte, Janssen, Leo, Novartis, Pfizer, Rapt, Regeneron, Sanofi Genzyme, Sun Pharma, and UCB Pharma. Dr Calabrese is a speaker for Sanofi-Regeneron and consultant for AbbVie. Dr Feldman has received research, speaking, and/or consulting support from Galderma, GlaxoSmithKline/Stiefel, Almirall, Alvotech, Leo Pharma, Bristol Myers Squibb, Boehringer Ingelheim, Mylan, Celgene, Pfizer, Ortho Dermatology, AbbVie, Samsung, Janssen, Lilly, Menlo, Merck, Novartis, Regeneron, Sanofi, Novan, Qurient, National Biological Corporation, Caremark, Advance Medical, Sun Pharma, Suncare Research, Informa, UpToDate, and National Psoriasis Foundation; has consulted for others through Guidepoint Global, Gerson Lehrman, and other consulting organizations; is the founder and majority owner of www.DrScore.com; and is a founder and part owner of Causa Research, a company dedicated to enhancing patients' adherence to treatment. Dr Gladman is a consultant for AbbVie, Amgen, Bristol Myers Squibb, Galapagos, Gilead, Eli Lilly, Janssen, Novartis, Pfizer, and UCB and has received grants from AbbVie, Amgen, Eli Lilly, Janssen, Novartis, Pfizer, and UCB. Dr Kircik has served either as an investigator, consultant, or speaker for AbbVie, Almirall, Amgen, Arcutis, Bausch Health Canada, Bristol Myers Squibb, Boehringer Ingelheim, Cellceutix, Celgene, Coherus, Dermavant, Dermira, Eli Lilly, Leo, MC2, Maruho, Novartis, Ortho Dermatologics, Pfizer, Dr Reddy's Laboratories, Sun Pharma, UCB, Taro, and Xenoport. Dr Lebwohl is an employee of Mount Sinai; receives research funds from AbbVie, Amgen, Arcutis, Boehringer Ingelheim, Dermavant, Eli Lilly, Incyte, Janssen Research and Development, Leo Pharmaceuticals, Ortho Dermatologics, Pfizer, and UCB; and is a consultant for Aditum Bio, Allergan, Almirall, Arcutis, Avotres Therapeutics, BirchBioMed, BMD Skincare, Boehringer Ingelheim, Bristol Myers Squibb, Cara Therapeutics, Castle Biosciences, Corrona, Dermavant Sciences, Evelo, Facilitate International Dermatologic Education, Foundation for Research and Education in Dermatology, Inozyme Pharma, Kyowa Kirin, LEO Pharma, Meiji Seika Pharma, Menlo, Mitsubishi, Neuroderm, Pfizer, Promius/Dr Reddy's Laboratories, Serono, Theravance, and Verrica. Dr Martin is a consultant for Almirall, Athenex, Bristol Meyers Squibb, Celgene, Eli Lilly, LEO, Ortho Dermatologic, Pfizer, and UCB and a scientific advisor for Almirall, Athenex, Bristol Meyers Squibb, Celgene, Eli Lilly, Janssen, LEO, Ortho Dermatologic, Pfizer, and UCB. Dr Merola is a consultant and/or investigator for Bristol Myers Squibb, AbbVie, Dermavant, Eli Lilly, Novartis, Janssen, UCB, Sun Pharma, Pfizer, and EMD Serono. Dr Scher is a consultant for UCB, Janssen, AbbVie, Pfizer, Novartis, Bristol Myers Squibb, and Sanofi and is supported in part by the Riley Family Foundation and the Beatrice Snyder Foundation. Dr Schwartzman is a speaker for AbbVie, Genentech, Janssen, Lilly, Novartis, Pfizer, and UCB; owns stock in Amgen, Boston Scientific, Gilead, Medtronic, and Pfizer; is a consultant for AbbVie, Myriad, Janssen, Gilead, Lilly, Novartis, and UCB; is a scientific advisory board member for Myriad; and is a board member of the National Psoriasis Foundation. Dr Van Voorhees has been an investigator for Celgene, Lilly, and AbbVie and an advisor/consultant for AbbVie, Allergan, AstraZeneca, Celgene, Dermira, Merck, Novartis, Pfizer, UCB, and Valeant. Dr Syed is supported by a grant from Pfizer. Authors Gondo, Heydon, and Koons are employees of the National Psoriasis Foundation. Dr Ritchlin reports personal fees from AbbVie, Amgen, Janssen, Novartis, UCB, and Boehringer Ingelheim, as well as grants from Amgen, UCB, and AbbVie outside the submitted work. Drs Dommasch, Lo Re, Treat, Ellebrecht, Fenner, Ocon, and Weinstein have no conflicts of interest to declare., (Copyright © 2021 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

Objective: To provide guidance about management of psoriatic disease during the coronavirus disease 2019 (COVID-19) pandemic., Study Design: A task force (TF) of 18 physician voting members with expertise in dermatology, rheumatology, epidemiology, infectious diseases, and critical care was convened. The TF was supplemented by nonvoting members, which included fellows and National Psoriasis Foundation (NPF) staff. Clinical questions relevant to the psoriatic disease community were informed by questions received by the NPF. A Delphi process was conducted., Results: The TF approved 22 guidance statements. The average of the votes was within the category of agreement for all statements. All guidance statements proposed were recommended, 9 with high consensus and 13 with moderate consensus., Limitations: The evidence behind many guidance statements is limited in quality., Conclusion: These statements provide guidance for the management of patients with psoriatic disease on topics ranging from how the disease and its treatments impact COVID-19 risk and outcome, how medical care can be optimized during the pandemic, what patients should do to lower their risk of getting infected with severe acute respiratory syndrome coronavirus 2 and what they should do if they develop COVID-19. The guidance is intended to be a living document that will be updated by the TF as data emerge., (Copyright © 2020 American Academy of Dermatology, Inc. Published by Elsevier Inc. All rights reserved.)

Desmoglein 3 chimeric autoantibody receptor T cells (DSG3-CAART) expressing the pemphigus vulgaris (PV) autoantigen DSG3 fused to CD137-CD3ζ signaling domains, represent a precision cellular immunotherapy approach for antigen-specific B cell depletion. Here, we present definitive preclinical studies enabling a first-in-human trial of DSG3-CAART for mucosal PV. DSG3-CAART specifically lysed human anti-DSG3 B cells from PV patients and demonstrated activity consistent with a threshold dose in vivo, resulting in decreased target cell burden, decreased serum and tissue-bound autoantibodies, and increased DSG3-CAART engraftment. In a PV active immune model with physiologic anti-DSG3 IgG levels, DSG3-CAART inhibited antibody responses against pathogenic DSG3 epitopes and autoantibody binding to epithelial tissues, leading to clinical and histologic resolution of blisters. DSG3 autoantibodies stimulated DSG3-CAART IFN-γ secretion and homotypic clustering, consistent with an activated phenotype. Toxicology screens using primary human cells and high-throughput membrane proteome arrays did not identify off-target cytotoxic interactions. These preclinical data guided the trial design for DSG3-CAART and may help inform CAART preclinical development for other antibody-mediated diseases.

Current therapies for autoimmunity cause significant morbidity and mortality. Adoptive immunotherapy using genetically engineered T cells has led to durable remissions of B cell leukemias and lymphomas, raising the question of whether the approach can be modified to target autoreactive B and T cells to induce durable remissions of autoimmunity. Here we review antigen-specific approaches to modify immune cells to treat autoimmune disease. We focus on recent studies that aim to eliminate or suppress autoimmunity by targeting the disease-causing B or T cells through their B cell receptor or T cell receptor specificities., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Lineage analysis of autoreactive B cells can reveal the origins of autoimmunity. In the autoimmune disease pemphigus vulgaris (PV), desmoglein 3 (DSG3) and DSG1 autoantibodies are predominantly of the IgG4 subclass and less frequently of IgG1 and IgA subclasses, prompting us to investigate whether anti-DSG IgG4 B cells share lineages with IgG1, IgA1, and IgA2. Combining subclass-specific B cell deep sequencing with high-throughput antibody screening, we identified 80 DSG-reactive lineages from 4 PV patients. Most anti-DSG IgG4 B cells lacked clonal relationships to other subclasses and preferentially targeted DSG adhesion domains, whereas anti-DSG IgA frequently evolved from or to other subclasses and recognized a broader range of epitopes. Our findings suggest that anti-DSG IgG4 B cells predominantly evolve independently or diverge early from other subclasses and that IgA is most often not the origin of IgG autoreactivity in PV. These data provide insight into how autoreactivity diversifies across B cell subclasses., (Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.)

This corrects the article DOI: 10.1038/nrdp.2018.13.

HIV is adept at avoiding naturally generated T cell responses; therefore, there is a need to develop HIV-specific T cells with greater potency for use in HIV cure strategies. Starting with a CD4-based chimeric antigen receptor (CAR) that was previously used without toxicity in clinical trials, we optimized the vector backbone, promoter, HIV targeting moiety, and transmembrane and signaling domains to determine which components augmented the ability of T cells to control HIV replication. This re-engineered CAR was at least 50-fold more potent in vitro at controlling HIV replication than the original CD4 CAR, or a TCR-based approach, and substantially better than broadly neutralizing antibody-based CARs. A humanized mouse model of HIV infection demonstrated that T cells expressing optimized CARs were superior at expanding in response to antigen, protecting CD4 T cells from infection, and reducing viral loads compared to T cells expressing the original, clinical trial CAR. Moreover, in a humanized mouse model of HIV treatment, CD4 CAR T cells containing the 4-1BB costimulatory domain controlled HIV spread after ART removal better than analogous CAR T cells containing the CD28 costimulatory domain. Together, these data indicate that potent HIV-specific T cells can be generated using improved CAR design and that CAR T cells could be important components of an HIV cure strategy.

Pemphigus is a group of IgG-mediated autoimmune diseases of stratified squamous epithelia, such as the skin and oral mucosa, in which acantholysis (the loss of cell adhesion) causes blisters and erosions. Pemphigus has three major subtypes: pemphigus vulgaris, pemphigus foliaceus and paraneoplastic pemphigus. IgG autoantibodies are characteristically raised against desmoglein 1 and desmoglein 3, which are cell-cell adhesion molecules found in desmosomes. The sites of blister formation can be physiologically explained by the anti-desmoglein autoantibody profile and tissue-specific expression pattern of desmoglein isoforms. The pathophysiological roles of T cells and B cells have been characterized in mouse models of pemphigus and patients, revealing insights into the mechanisms of autoimmunity. Diagnosis is based on clinical manifestations and confirmed with histological and immunochemical testing. The current first-line treatment is systemic corticosteroids and adjuvant therapies, including immunosuppressive agents, intravenous immunoglobulin and plasmapheresis. Rituximab, a monoclonal antibody against CD20 + B cells, is a promising therapeutic option that may soon become first-line therapy. Pemphigus is one of the best-characterized human autoimmune diseases and provides an ideal paradigm for both basic and clinical research, especially towards the development of antigen-specific immune suppression treatments for autoimmune diseases.

Pemphigus vulgaris (PV) is an epithelial blistering disease caused by autoantibodies to the desmosomal cadherin desmoglein 3 (DSG3). Glucocorticoids improve disease within days by increasing DSG3 gene transcription, although the mechanism for this observation remains unknown. Here, we show that DSG3 transcription in keratinocytes is regulated by Stat3. Treatment of primary human keratinocytes (PHKs) with hydrocortisone or rapamycin, but not the p38 MAPK inhibitor SB202190, significantly increases DSG3 mRNA and protein expression and correspondingly reduces phospho-S727 Stat3. Stat3 inhibition or shRNA-knockdown also significantly increases DSG3 mRNA and protein levels. Hydrocortisone- or rapamycin-treated PHKs demonstrate increased number and length of desmosomes by electron microscopy and are resistant to PV IgG-induced loss of cell adhesion, whereas constitutive activation of Stat3 in PHKs abrogates DSG3 upregulation and inhibits hydrocortisone and rapamycin's therapeutic effects. Topical hydrocortisone, rapamycin, or Stat3 inhibitor XVIII prevents autoantibody-induced blistering in the PV passive transfer mouse model, correlating with increased epidermal DSG3 expression and decreased phospho-S727 Stat3. Our data indicate that glucocorticoids and rapamycin upregulate DSG3 transcription through inhibition of Stat3. These studies explain how glucocorticoids rapidly improve pemphigus and may also offer novel insights into the physiologic and pathophysiologic regulation of desmosomal cadherin expression in normal epidermis and epithelial carcinomas.

Despite the rising incidence of autoimmunity, therapeutic options for patients with autoimmune disease still rely on decades-old immunosuppressive strategies that risk severe and potentially fatal complications. Thus, novel therapeutic approaches for autoimmune diseases are greatly needed in order to minimize treatment-related toxicity. Such strategies would ideally target only the autoreactive immune components to preserve beneficial immunity. Here, we review how several decades of basic, translational, and clinical research on the immunology of pemphigus vulgaris (PV), an autoantibody-mediated skin disease, have enabled the development of targeted immunotherapeutic strategies. We discuss research to elucidate the pathophysiology of PV and how the knowledge afforded by these studies has led to the preclinical and clinical testing of targeted approaches to neutralize autoantibodies, to induce antigen-specific tolerance, and to specifically eliminate autoreactive B cells in PV., Competing Interests: Conflict of interest: A.S. Payne and C.T. Ellebrecht are inventors on patents related to targeted therapy of autoimmune diseases (PCT/US15/28872), including pemphigus. A.S. Payne has received research funding from Sanofi for the development of cellular immunotherapies for pemphigus.

In autoantibody-mediated diseases such as pemphigus, serum antibodies lead to disease. Genetic analysis of B cells has allowed characterization of antibody repertoires in such diseases but would be complemented by proteomic analysis of serum autoantibodies. Here, we show using proteomic analysis that the serum autoantibody repertoire in pemphigus is much more polyclonal than that found by genetic studies of B cells. In addition, many B cells encode pemphigus autoantibodies that are not secreted into the serum. Heavy chain variable gene usage of serum autoantibodies is not shared among patients, implying targeting of the coded proteins will not be a useful therapeutic strategy. Analysis of autoantibodies in individual patients over several years indicates that many antibody clones persist but the proportion of each changes. These studies indicate a dynamic and diverse autoantibody response not revealed by genetic studies and explain why similar overall autoantibody titers may give variable disease activity., Competing Interests: JL and LK are employees of the Euroimmun AG, a company that develops, produces and manufactures immunoassays for the detection of disease-associated antibodies. The other authors have nothing to disclose., (Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.)

Shared VH1-46 gene usage has been described in B cells reacting to desmoglein 3 (Dsg3) in the autoimmune disease pemphigus vulgaris (PV), as well as B cells responding to rotavirus capsid protein VP6. In both diseases, VH1-46 B cells bearing few to no somatic mutations can recognize the disease Ag. This intriguing connection between an autoimmune response to self-antigen and an immune response to foreign Ag prompted us to investigate whether VH1-46 B cells may be predisposed to Dsg3-VP6 cross-reactivity. Focused testing of VH1-46 mAbs previously isolated from PV and rotavirus-exposed individuals indicates that cross-reactivity is rare, found in only one of seven VH1-46 IgG clonotypes. High-throughput screening of IgG B cell repertoires from two PV patients identified no additional cross-reactive clonotypes. Screening of IgM B cell repertoires from one non-PV and three PV patients identified specific cross-reactive Abs in one PV patient, but notably all six cross-reactive clonotypes used VH1-46. Site-directed mutagenesis studies indicate that amino acid residues predisposing VH1-46 Abs to Dsg3 reactivity reside in CDR2. However, somatic mutations only rarely promote Dsg3-VP6 cross-reactivity; most mutations abolish VP6 and/or Dsg3 reactivity. Nevertheless, functional testing identified two cross-reactive VH1-46 Abs that both disrupt keratinocyte adhesion and inhibit rotavirus replication, indicating the potential for VH1-46 Abs to have both pathologic autoimmune and protective immune functions. Taken together, these studies suggest that certain VH1-46 B cell populations may be predisposed to Dsg3-VP6 cross-reactivity, but multiple mechanisms prevent the onset of autoimmunity after rotavirus exposure., (Copyright © 2016 by The American Association of Immunologists, Inc.)

The mechanisms underlying the maintenance of long-lasting humoral immunity are not well understood. Studies in mice indicate that plasma cells (PCs) can survive up to a lifetime, even in the absence of regeneration by B cells, implying the presence of long-lived PCs as a mechanism for long-lasting immunity. Evidence from humans treated with anti-CD20, which depletes circulating B cells, also suggests B-cell-independent long-term survival of some PCs. On the other hand, antibody responses may be sustained solely by short-lived PCs with repopulation from clonally related memory B cells. To explore PC longevity and humoral immunity in humans, we investigated the fate of PCs and their antibodies in adult and pediatric patients who received chimeric antigen receptor-based adoptive T-cell immunotherapy targeting CD19 to treat B-cell lineage malignancies (CTL019). Treatment with CTL019 is frequently associated with B-cell aplasia that can persist for years. Serum antibody titers to vaccine-related antigens were measured, and quantitative assessment of B cells and PCs in blood and bone marrow was performed at various time points before and after CTL019 therapy. While total serum immunoglobulin concentrations decline following CTL019-induced B-cell aplasia, several vaccine/pathogen-specific serum immunoglobulin G and A (IgG and IgA) titers remain relatively stable for at least 6 and 12 months posttreatment, respectively. Analysis of bone marrow biopsies after CTL019 revealed 8 patients with persistence of antibody-secreting PCs at least 25 months post-CTL019 infusion despite absence of CD19(+)CD20(+) B cells. These results provide strong evidence for the existence of memory B-cell-independent, long-lived PCs in humans that contribute to long-lasting humoral immunity., (© 2016 by The American Society of Hematology.)

Ideally, therapy for autoimmune diseases should eliminate pathogenic autoimmune cells while sparing protective immunity, but feasible strategies for such an approach have been elusive. Here, we show that in the antibody-mediated autoimmune disease pemphigus vulgaris (PV), autoantigen-based chimeric immunoreceptors can direct T cells to kill autoreactive B lymphocytes through the specificity of the B cell receptor (BCR). We engineered human T cells to express a chimeric autoantibody receptor (CAAR), consisting of the PV autoantigen, desmoglein (Dsg) 3, fused to CD137-CD3ζ signaling domains. Dsg3 CAAR-T cells exhibit specific cytotoxicity against cells expressing anti-Dsg3 BCRs in vitro and expand, persist, and specifically eliminate Dsg3-specific B cells in vivo. CAAR-T cells may provide an effective and universal strategy for specific targeting of autoreactive B cells in antibody-mediated autoimmune disease., (Copyright © 2016, American Association for the Advancement of Science.)

Pemphigus vulgaris (PV) is characterized by IgG1 and IgG4 autoantibodies to desmoglein (Dsg) 3, causing suprabasal blistering of skin and mucous membranes. IgG4 is the dominant autoantibody subclass in PV and correlates with disease activity, whereas IgG1 can be associated with remittent disease. It is unknown if switching the same variable region between IgG4 and IgG1 directly impacts pathogenicity. Here, we tested whether three pathogenic PV monoclonal antibodies (mAbs) from three different patients demonstrate differences in antigen affinity, epitope specificity, or pathogenicity when expressed as IgG1 or IgG4. F706 anti-Dsg3 IgG4 and F779 anti-Dsg3 IgG1, previously isolated as heterohybridomas, and Px43, a monovalent anti-Dsg3/Dsg1 IgG antibody isolated by phage display, were subcloned to obtain paired sets of IgG1 and IgG4 mAbs. Using ELISA and cell surface staining assays, F706 and F779 demonstrated similar antigen binding affinities of IgG1 and IgG4, whereas Px43 showed 3- to 8-fold higher affinity of IgG4 versus IgG1 by ELISA, but identical binding affinities to human skin, perhaps due to targeting of a quaternary epitope best displayed in tissues. All 3 mAb pairs targeted the same extracellular cadherin (EC) domain on Dsg3, caused Dsg3 internalization in primary human keratinocytes, and caused suprabasal blisters in human skin at comparable doses. We conclude that switching IgG1 and IgG4 subclasses of pathogenic PV mAbs does not directly affect their antigen binding or pathogenic properties.

Epidermolysis bullosa acquisita (EBA) is a chronic autoimmune blistering skin disease characterized by autoantibodies against type VII collagen (COL7). Immunization of SJL/J mice with recombinant murine COL7 results in break of tolerance and skin blisters. Strikingly, despite circulating autoantibodies, the same genetic background and identical environmental conditions, 20% of mice remain healthy. To elucidate the regulation of the transition from the presence of autoantibodies to overt autoimmune disease, we characterized the innate and adaptive immune response of mice that remain healthy after immunization and compared it to mice that developed skin disease. Both clinically healthy and diseased SJL/J mice showed circulating autoantibodies and deposition of complement-fixing IgG2c autoantibodies and C3 at the dermal-epidermal junction. However, only in diseased animals significant neutrophil infiltration and increase in FcgRIV expression were observed in the skin. In contrast, the expression of T cell signature cytokines in the T cell zone of the draining lymph node was comparable between clinically healthy and diseased animals after immunization. Surprisingly, health was associated with a decreased expression of CD11c, TNFA and KC (CXCL1) in the skin prior to immunization and could be predicted with a negative predictive value of >80%. Furthermore, mice that did not develop clinical disease showed a significantly higher richness and distinctly clustered diversity of their skin microbiota before immunization. Our data indicate that the decision whether blisters develop in the presence of autoantibodies is governed in the skin rather than in the lymph node, and that a greater richness of cutaneous bacterial species appears to be protective., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Laparoscopic colon and rectum operations expose peripheral nerves to risk due to extreme patient positions needed to achieve gravity displacement during the surgical procedures. The general incidence of position-caused nerve injuries in surgery is not well known and is estimated to be about 0.5 % in the literature. There are no current data concerning laparoscopic operations. This study assesses the incidence and outcome of surgery-associated neurological symptoms after laparoscopic colon and rectum surgical procedures. We analysed the number of position-caused nerve injuries and their outcome from 1992-2010 in a prospectively managed data base. Risk factors like age, BMI, procedure duration and abduction of the upper extremities were analysed. There were 19 (0.7 %) position-caused nerve injuries among 2698 laparoscopic operations on the colon and rectum. The incidence of surgery-associated neurological symptoms was 1.08 % after laparoscopic rectum and 0.54 % after laparoscopic colon surgical procedures. Both operation time (267 vs. 185 minutes) and BMI (27.93 vs. 25.79 kg/m(2)) were revealed as risk factors for position-caused nerve injuries. Adduction of the upper extremities reduced the incidence of positioning nerve injuries from 0.23 % to 0.1 %. Postoperative neurological symptoms were in most cases reversible (89.47 %). The incidence of postoperative nerve injuries since 2007 is low after laparoscopic rectum and colon operations and is mostly completely reversible. Both procedure duration and BMI are probable risk factors for surgery-associated nerve injuries. Adduction of the upper extremities provides an opportunity to reduce position-caused nerve injuries., (Georg Thieme Verlag KG Stuttgart · New York.)

The immunomodulatory cytokine interleukin-10 (IL-10) plays beneficial but also potentially detrimental roles in inflammation, infection, and autoimmunity. Recent studies suggest a regulatory role for IL-10-expressing B cells in the autoimmune blistering disease pemphigus vulgaris. Here we review the studies on IL-10 in pemphigus vulgaris and discuss the potential pathophysiological significance of these findings in comparison to prior studies of IL-10 in other human conditions. A better understanding of the complex roles of IL-10 in immune regulation may improve our understanding of pemphigus pathogenesis and treatment., (Copyright © 2014 Elsevier Ltd. All rights reserved.)

IMPORTANCE B-cell depletion with the anti-CD20 antibody rituximab is highly effective for pemphigus vulgaris (PV) treatment. However,most patients experience relapse, and intravenous rituximab infusions are expensive. Therefore, cost-effective anti-CD20 therapies are desirable.OBSERVATIONS A compassionate-use investigational new drug protocol was approved to administer veltuzumab, a second-generation humanized anti-CD20 antibody, to a patient with refractory PV. Veltuzumab was administered as two 320-mg (188mg/m2) subcutaneous doses 2 weeks apart, resulting in complete remission of disease off therapy. The disease relapsed 2 years after treatment. A second cycle of subcutaneous veltuzumab, using the same dosage regimen, again induced complete remission off therapy, which remained at9 months. No serious adverse events occurred during 35 months of follow-up. Serum veltuzumab levels were 22 and 29 μg/mL 2 weeks after the first dose of each cycle, and the drug remained detectable in the serum for longer than 3 months. Relapse and response to veltuzumab generally correlated with desmoglein 3 enzyme-linked immunosorbent assay index values. Shortly after a relapse that occurred after a long-term remission, the patient demonstrated an elevated naive (CD19+CD27−) to memory (CD19+CD27+) B-cell ratio of 19.5 and transitional (CD19+CD24+CD38+) B-cell frequency of 12.5%.CONCLUSIONS AND RELEVANCE Subcutaneous veltuzumab may be a safe, effective, and more economical alternative to intravenous rituximab for PV therapy. Clinical trials of subcutaneous veltuzumab for PV are warranted.

Pemphigus vulgaris (PV) is a potentially fatal blistering disease caused by autoantibodies (autoAbs) against desmoglein 3 (Dsg3). Here, we clone anti-Dsg3 antibodies (Abs) from four PV patients and identify pathogenic VH1-46 autoAbs from all four patients. Unexpectedly, VH1-46 autoAbs had relatively few replacement mutations. We reverted antibody somatic mutations to their germline sequences to determine the requirement of mutations for autoreactivity. Three of five VH1-46 germline-reverted Abs maintain Dsg3 binding, compared with zero of five non-VH1-46 germline-reverted Abs. Site-directed mutagenesis of VH1-46 Abs demonstrates that acidic amino-acid residues introduced by somatic mutation or heavy chain VDJ recombination are necessary and sufficient for Dsg3 binding. Our data suggest that VH1-46 autoantibody gene usage is commonly found in PV because VH1-46 Abs require few to no mutations to acquire Dsg3 autoreactivity, which may favour their early selection. Common VH gene usage indicates common humoral immune responses, even among unrelated patients.

The importance of desmosomal cell adhesion to human health is evidenced by the autoimmune disease pemphigus vulgaris (PV), in which autoantibodies against the extracellular domain of the desmosomal cadherin desmoglein 3 cause potentially fatal blistering of the skin and mucous membranes. Tucker et al. describe how enhanced expression of a desmosomal cytoplasmic plaque protein, plakophilin-1, protects keratinocytes from PV IgG-induced loss of cell adhesion by inducing calcium-independent hyperadhesive desmosomes. This study beautifully demonstrates that desmosomal adhesion can be modulated by the molecular interactions of the desmoglein tail and suggests that these novel regulatory pathways may possibly be exploited in treating human disease.

Background: Pemphigus vulgaris (PV) and pemphigus foliaceus (PF) are potentially fatal blistering diseases caused by autoantibodies targeting desmoglein (Dsg) adhesion proteins. Previous studies have shown an IgG4 > IgG1 predominance of anti-Dsg antibodies in pemphigus; however, no studies have examined total serum IgG4 levels in pemphigus. IgG4 is induced by chronic antigen stimulation, which could occur with persistent skin blistering and potentially elevate the total serum IgG4 relative to other IgG subclasses in patients with pemphigus., Objectives: The primary aim of the study was to quantitate total and Dsg-specific IgG subclasses in patients with pemphigus., Methods: IgG subclasses and Dsg-specific IgG1 and IgG4 were quantitated in patients with PV and PF, and in sera from age-matched controls using a subclass enzyme-linked immunosorbent assay. The effectiveness of IgG4 depletion in blocking IgG pathogenicity in PV was determined using a keratinocyte dissociation assay., Results: Dsg-specific antibodies comprised a median of 7·1% and 4·2% of total IgG4 in patients with PV and PF, respectively, with eightfold and fourfold enrichment in IgG4 vs. IgG1. Total serum IgG4, but not other IgG subclasses, was enriched in patients with PV and PF compared with age-matched controls (P = 0·004 and P = 0·005, respectively). IgG4 depletion of PV sera reduced pathogenicity in a keratinocyte dissociation assay and showed that affinity-purified IgG4 is more pathogenic than other serum IgG fractions., Conclusions: Dsg-specific autoantibodies are significantly enriched in IgG4, which may explain the enrichment of total serum IgG4 in some patients with pemphigus. By preferentially targeting autoimmune rather than beneficial immune antibodies, IgG4-targeted therapies may offer safer treatment options for pemphigus., (© 2012 The Authors. BJD © 2012 British Association of Dermatologists 2012.)

The environment encountered in secondary lymphoid organs (e.g., lymph nodes) influences the outcome of immune responses. Immunization of mice with type VII collagen, an adhesion protein expressed at the cutaneous basement membrane, induces experimental epidermolysis bullosa acquisita (EBA). In this model, clinical disease is associated with the H2s haplotype of the MHC found in SJL/J mice. Most other strains (e.g., BALB/c, C57BL/6, NZM2410/J) are resistant to clinical disease, despite autoantibody production. Comparison of autoantibody response in EBA-resistant and -susceptible mice showed an IgG2-dominated response in the latter. We hypothesized that EBA susceptibility is due to specific cytokine gene expression in draining lymph nodes (dLN). To challenge this hypothesis, EBA-susceptible (SJL/J) and -resistant (BALB/c, C57BL/6) mice were immunized with type VII collagen, followed by analysis of clinical phenotype, subclasses of circulating and tissue-bound autoantibodies, complement activation, and cytokine gene expression in dLN. Disease manifestation was associated with induction of complement-fixing autoantibodies, confirming previous observations. Furthermore, however, IFN-γ/IL-4 ratio in dLN of EBA-susceptible mice was significantly increased compared with EBA-resistant strains, suggesting a Th1 polarization. Immunization of H2s-congenic C57BL/6 mice (B6.SJL-H2s) led to Th1 polarization in dLN and clinical disease. In addition to their cytokine milieu, EBA-susceptible and -resistant mice also differed regarding the expression of FcγR on peripheral leukocytes, in which a higher FcγRIV expression in SJL/J and B6.SJL-H2s mice, compared with C57BL/6, was associated with skin lesions. In summary, blistering in experimental EBA is regulated by both adaptive (divergent class switch recombination due to polarized cytokine expression) and innate (FcγR expression) immune mechanisms.