Bullous pemphigoid induced by IgG targeting type XVII collagen non-NC16A/NC15A extracellular domains is driven by Fc gamma receptor- and complement-mediated effector mechanisms and is ameliorated by neonatal Fc receptor blockade.

Bullous pemphigoid (BP) is an autoimmune blistering disease characterized by autoantibodies targeting type XVII collagen (Col17) with the noncollagenous 16A (NC16A) ectodomain representing the immunodominant site. The role of additional extracellular targets of Col17 outside NC16A has not been unequivocally demonstrated. In this study, we showed that Col17 ectodomain-reactive patient sera depleted in NC16A IgG induced dermal-epidermal separation in a cryosection model indicating the pathogenic potential of anti-Col17 non-NC16A extracellular IgG. Moreover, injection of IgG targeting the murine Col17 NC14-1 domains (downstream of NC15A, the murine homologue of human NC16A) into C57BL/6J mice resulted in erythematous skin lesions and erosions. Clinical findings were accompanied by IgG/C3 deposits along the basement membrane and subepidermal blistering with inflammatory infiltrates. Disease development was significantly reduced in either Fc-gamma receptor (FcγR)- or complement-5a receptor-1 (C5aR1)-deficient mice. Inhibition of the neonatal FcR (FcRn), an atypical FcγR regulating IgG homeostasis, with the murine Fc fragment IgG2c-ABDEG, a derivative of efgartigimod, reduced anti-NC14-1 IgG levels, resulting in ameliorated skin inflammation compared with isotype-treated controls. These data demonstrate that the pathogenic effects of IgG targeting the Col17 domain outside human NC16A/murine NC15A are partly attributable to antibody-mediated FcγR- and C5aR1 effector mechanisms while pharmacological inhibition of the FcRn represents a promising treatment for BP. The mouse model of BP will be instrumental in further investigating the role of Col17 non-NC16A/NC15A extracellular epitopes and validating new therapies for this disease. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

C3d-Targeted factor H inhibits tissue complement in disease models and reduces glomerular injury without affecting circulating complement.

Complement-mediated diseases can be treated using systemic inhibitors. However, complement components are abundant in circulation, affecting systemic inhibitors' exposure and efficacy. Furthermore, because of complement's essential role in immunity, systemic treatments raise infection risk in patients. To address these challenges, we developed antibody fusion proteins combining the alternative-pathway complement inhibitor factor H (fH1-5) with an anti-C3d monoclonal antibody (C3d-mAb-2fH). Because C3d is deposited at sites of complement activity, this molecule localizes to tissue complement while minimizing circulating complement engagement. These fusion proteins bind to deposited complement in diseased human skin sections and localize to activated complement in a primate skin injury model. We further explored the pharmacology of C3d-mAb-2fH proteins in rodent models with robust tissue complement activation. Doses of C3d-mAb-2fH >1 mg/kg achieved >75% tissue complement inhibition in mouse and rat injury models while avoiding circulating complement blockade. Glomerular-specific complement inhibition reduced proteinuria and preserved podocyte foot-process architecture in rat membranous nephropathy, indicating disease-modifying efficacy. These data indicate that targeting local tissue complement results in durable and efficacious complement blockade in skin and kidney while avoiding systemic inhibition, suggesting broad applicability of this approach in treating a range of complement-mediated diseases.

High throughput screening identifies repurposable drugs for modulation of innate and acquired immune responses.

A balanced immune system is essential to maintain adequate host defense and effective self-tolerance. While an immune system that fails to generate appropriate response will permit infections to develop, uncontrolled activation may lead to autoinflammatory or autoimmune diseases. To identify drug candidates capable of modulating immune cell functions, we screened 1200 small molecules from the Prestwick Chemical Library for their property to inhibit innate or adaptive immune responses. Our studies focused specifically on drug interactions with T cells, B cells, and polymorphonuclear leukocytes (PMNs). Candidate drugs that were validated in vitro were examined in preclinical models to determine their immunomodulatory impact in chronic inflammatory diseases, here investigated in chronic inflammatory skin diseases. Using this approach, we identified several candidate drugs that were highly effective in preclinical models of chronic inflammatory disease. For example, we found that administration of pyrvinium pamoate, an FDA-approved over-the-counter anthelmintic drug, suppressed B cell activation in vitro and halted the progression of B cell-dependent experimental pemphigoid by reducing numbers of autoantigen-specific B cell responses. In addition, in studies performed in gene-deleted mouse strains provided additional insight into the mechanisms underlying these effects, for example, the receptor-dependent actions of tamoxifen that inhibit immune-complex-mediated activation of PMNs. Collectively, our methods and findings provide a vast resource that can be used to identify drugs that may be repurposed and used to promote or inhibit cellular immune responses.

Granzyme B inhibition reduces autoantibody-induced dermal-epidermal separation in an ex vivo model of epidermolysis bullosa acquisita.

The pemphigoid disease epidermolysis bullosa acquisita (EBA) is an autoimmune blistering skin disease characterized by autoantibodies against type VII collagen (COL7), immune cell infiltrates at the dermal-epidermal junction and subepidermal blistering. Proteases, particularly granzyme B (GzmB), have been established as therapeutic targets for the treatment of EBA and other pemphigoid diseases. We investigated the impact of the novel GzmB inhibitor SNT-6935 on anti-COL7 IgG-induced subepidermal blistering in a well-established EBA ex vivo model. Our findings demonstrate that pharmacological targeting of GzmB with its selective inhibitor SNT-6935 significantly reduced autoantibody-induced dermal-epidermal separation in human skin cryosections. Interestingly, treatment of skin cryosections with recombinant human GzmB alone did not cause dermal-epidermal separation, suggesting that additional mechanisms alongside GzmB are required for tissue damage in EBA. In conclusion, our study highlights the significant contribution of GzmB to the pathogenesis of EBA and supports the notion of GzmB as a therapeutic target in EBA and other pemphigoid diseases.

Anti-TNF therapy impairs both short- and long-term IgG responses after repeated vaccination.

BACKGROUND: Recently, it has been questioned whether vaccination of patients with inflammatory (auto)immune diseases under anti-tumor necrosis factor (TNF) treatment leads to impaired vaccine-induced immune responses and protection against breakthrough infections. However, the effects of TNF blockade on short- and long-term immune responses after repeated vaccination remain unclear. Vaccination studies have shown that initial short-term IgG antibodies (Abs) carry highly galactosylated and sialylated Fc glycans, whilst long-term IgG Abs have low levels of galactosylation and sialylation and are most likely generated by long-lived plasma cells (PCs) derived primarily from the germinal center (GC) response. Thus, IgG Fc glycosylation patterns may be applicable to distinguish short- and long-term vaccine responses after repeated vaccination under the influence of anti-TNF treatment. METHODS: We used COVID-19 vaccination as a model to investigate vaccine-induced IgG subclass levels and Fc glycosylation patterns, B cell subsets, and effector functions of short- and long-term Ab responses after up to three vaccinations in patients on anti-TNF or other immunosuppressive treatments and in healthy individuals. Using TriNetX, a global healthcare database, we determined the risk of SARS-CoV-2 breakthrough infections in vaccinated patients treated with anti-TNF or other immunosuppressive drugs. RESULTS: Anti-TNF treatment reduced the long-term abundance of all anti-S IgG subclasses with low levels of galactosylation and sialylation. Re-activation of potential memory B cells initially generated highly galactosylated and sialylated IgG antibodies, which were progressively reduced after each booster dose in anti-TNF-treated patients, especially in the elderly. The reduced short- and long-term IgG (1) levels in anti-TNF-treated patients correlated with diminished functional activity and an increased risk for the development of COVID-19. CONCLUSIONS: The data suggest that anti-TNF treatment reduces both GC-dependent long-lived PCs and GC-dependent memory B cell-derived short-lived PCs, hence both the long- and short-term IgG subclass responses, respectively, after repeated vaccination. We propose that anti-TNF therapy, especially in the elderly, reduces the benefit of booster vaccination.

Risk of death, major adverse cardiac events and relapse in patients with bullous pemphigoid treated with systemic or topical corticosteroids.

BACKGROUND: According to current guidelines, systemic or topical corticosteroids are both recommended as first-line treatments for bullous pemphigoid (BP). There is evidence to suggest that topical application may be associated with a lower risk of mortality. However, there is a lack of comprehensive large-scale data comparing mortality rates, as well as the risk of major adverse cardiac events (MACE), infections and relapse, between systemic and topical corticosteroid treatments. OBJECTIVES: To evaluate the risk of death, MACE, infections and relapse in patients with BP treated with systemic or topical corticosteroids. METHODS: A population-based retrospective cohort study was performed using the TriNetX US Collaborative Network. As a measure against bias, propensity score matching for age, sex, 10 diseases and 6 medications was done, and 3 sensitivity analyses were conducted. RESULTS: All-time risk of death was increased in US patients with BP exposed to any dose of systemic corticosteroids (n = 2917) vs. patients treated with topical clobetasol propionate [n = 2932; hazard ratio (HR) 1.43, 95% confidence interval (CI) 1.28-1.58 (P < 0.001)]. This was consistent in time-stratified analysis (1- and 3-year mortality rates) and in analysis contrasting prednisone (equivalent) doses of 1-10 mg (low) or 30-100 mg (medium-high) systemic corticosteroid to topical treatment. The increased risk of death in US patients with BP exposed to any dose of systemic corticosteroids vs. topical treatment was accompanied by increased risks for MACE (HR 1.33, 95% CI 1.08-1.64; P = 0.008) and infections (HR 1.33, 95% CI 1.15-1.54; P < 0.001). The risk of continued disease or relapse was decreased in patients treated with systemic vs. topical corticosteroids (HR 0.85, 95% CI 0.77-0.94; P = 0.002). Results regarding mortality and continued disease or relapse persisted in three sensitivity analyses. Potential limitations included the retrospective data collection, bias for treatment selection and miscoding. CONCLUSIONS: Pending validation in prospective studies, where feasible - and despite the heightened risk of relapse - topical corticosteroid treatment may be advantageous over systemic corticosteroid treatment owing to its significantly lower risk of death.

Bullous pemphigoid (BP) is an autoimmune skin disease that commonly affects older people. The recommended treatment is medication called corticosteroids, either taken as a tablet or injection ('systemic') or applied to the skin ('topical'). Some evidence suggests that topical corticosteroids might be safer in terms of the risk of dying. We looked at whether there was a difference between the risk of dying, having heart problems, getting sick or the condition coming back in people with BP who use the different medications. To do this, we used people's past health information and compared people of similar ages and genders, 10 diseases and 6 medications. We found that people with BP who used systemic corticosteroids had a higher chance of dying. This also meant that people taking this form of the medication had a greater chance of having heart problems and getting infections. However, the risk of BP coming back was lower for people who used systemic corticosteroids. Our findings suggest that although there is a higher risk of BP coming back, there may be fewer risks from topical corticosteroids than systemic corticosteroids.

Forward genetics and functional analysis highlight Itga11 as a modulator of murine psoriasiform dermatitis.

Psoriasis is a chronic inflammatory skin condition. Repeated epicutaneous application of Aldara® (imiquimod) cream results in psoriasiform dermatitis in mice. The Aldara®-induced psoriasiform dermatitis (AIPD) mouse model has been used to examine the pathogenesis of psoriasis. Here, we used a forward genetics approach in which we compared AIPD that developed in 13 different inbred mouse strains to identify genes and pathways that modulated disease severity. Among our primary results, we found that the severity of AIPD differed substantially between different strains of inbred mice and that these variations were associated with polymorphisms in Itga11. The Itga11 gene encodes the integrin α11 subunit that heterodimerizes with the integrin ß1 subunit to form integrin α11ß1. Less information is available about the function of ITGA11 in skin inflammation; however, a role in the regulation of cutaneous wound healing, specifically the development of dermal fibrosis, has been described. Experiments performed with Itga11 gene-deleted (Itga11-/- ) mice revealed that the integrin α11 subunit contributes substantially to the clinical phenotype as well as the histopathological and molecular findings associated with skin inflammation characteristic of AIPD. Although the skin transcriptomes of Itga11-/- and WT mice do not differ from one another under physiological conditions, distinct transcriptomes emerge in these strains in response to the induction of AIPD. Most of the differentially expressed genes contributed to extracellular matrix organization, immune system, and metabolism of lipids pathways. Consistent with these findings, we detected a reduced number of fibroblasts and inflammatory cells, including macrophages, T cells, and tissue-resident memory T cells in skin samples from Itga11-/- mice in response to AIPD induction. Collectively, our results reveal that Itga11 plays a critical role in promoting skin inflammation in AIPD and thus might be targeted for the development of novel therapeutics for psoriasiform skin conditions. © 2023 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Atopic dermatitis is associated with an increased risk of cardiovascular diseases: A large-scale, propensity-matched US-based retrospective study.

BACKGROUND: Atopic dermatitis is a chronic relapsing inflammatory skin disease characterized by intense itch impacting heavily on patients' and caregivers' quality of life. Its clinical presentation is accompanied by a variety of type 2 comorbidities, e.g. asthma, hay fever, food allergies. However, current data on cardiovascular comorbidities are inconsistent. OBJECTIVES: To identify risk of cardiovascular diseases in patients with atopic dermatitis. METHODS: Data from Electronic Health Records (EHRs) of 1,070,965 atopic dermatitis patients and equally propensity score matched controls were retrieved from the US Collaborative Network part of the federated TriNetX network. Hazard ratios for risk of onset of cardiovascular diseases with a prevalence of ≥1% in both cohorts within 20 years after diagnosis were determined. RESULTS: A total of 55 cardiovascular diseases belonging to 8 major cardiovascular groups were identified. Of those, 53 diagnoses displayed a significantly increased risk in atopic dermatitis patients. Different diagnoses of heart failure and heart disease were found most often, followed by valve insufficiencies, arrhythmia, tachycardia, atrial fibrillation, flutter, but also MACE and venous thromboembolism. The individual diagnoses venous insufficiency, atherosclerosis of native arteries of the extremities, and unspecified diastolic (congestive) heart failure displayed highest hazard ratios. CONCLUSION: Atopic dermatitis is associated with an increased risk for multiple cardiovascular diseases.

Are interleukin 17 and interleukin 23 inhibitors associated with malignancies?-Insights from an international population-based study.

BACKGROUND: Cancer risk after long-term exposure to interleukin (IL)-23 inhibitors (IL-23i) and IL-17 inhibitors (IL-17i) remains to be delineated. OBJECTIVE: To evaluate the risk of malignancies in patients with psoriasis treated with IL-23i and IL-17i relative to those prescribed tumour necrosis factor inhibitors (TNFi) during the first 5 years following drug initiation. METHODS: A global population-based cohort study included two distinct analyses comparing patients with psoriasis under different therapeutic modalities; (i) new users of IL-17i(n = 15,331) versus TNFi (n = 15,331) and (ii) new users of IL-23i (n = 5832) versus TNFi (n = 5832). RESULTS: Patients prescribed IL-17i experienced a decreased risk of non-Hodgkin lymphoma (NHL; HR, 0.58; 95% CI, 0.40-0.82; p = 0.002), colorectal cancer (HR, 0.68; 95% CI, 0.49-0.95; p = 0.024), hepatobiliary cancer (HR, 0.68; 95% CI, 0.58-0.80; p < 0.001), ovary cancer (HR, 0.48; 95% CI, 0.29-0.81; p = 0.005), melanoma (HR, 0.52; 95% CI, 0.37-0.73; p < 0.001), and basal cell carcinoma (BCC; HR, 0.57; 95% CI, 0.48-0.67; p < 0.001). IL-23i was associated with a reduced risk of NHL (HR, 0.39; 95% CI, 0.19-0.78; p = 0.006), hepatobiliary cancer (HR, 0.44; 95% CI, 0.31-0.62; p < 0.001) and BCC (HR, 0.76; 95% CI, 0.57-0.99; p = 0.046). In a sensitivity analysis comparing patients managed by IL-17i and IL-23i with their biologic-naïve counterparts, these classes were associated with decreased risk of several malignancies. CONCLUSION: IL-17i and IL-23i are associated with decreased risk of several malignancies. These findings should be considered prior to the prescription of biologics.

Risk of infections in patients with pemphigus treated with rituximab vs. azathioprine or mycophenolate mofetil: a large-scale global cohort study.

BACKGROUND: The risk of infectious complications among patients with pemphigus managed by rituximab is yet to be precisely elucidated. OBJECTIVES: To evaluate the risk of infections in patients with pemphigus managed by rituximab vs. first-line corticosteroid-sparing agents [azathioprine and mycophenolate mofetil (MMF)]. METHODS: A global population-based cohort study compared patients with pemphigus initiating rituximab (n = 963) vs. azathioprine or MMF (n = 963) regarding the risk of 26 different infections. Propensity score matching was conducted to optimize comparability. RESULTS: During the initial 12 months following treatment, patients under rituximab experienced elevated risk of COVID-19 [hazard ratio (HR) 1.82, 95% confidence interval (CI) 1.06-3.14; P = 0.028], parasitic diseases (HR 3.22, 95% CI 1.04-9.97; P = 0.032) and cytomegalovirus (CMV) infection (HR 1.63, 95% CI 1.04-2.58; P = 0.033). When evaluating infections developing ≥ 12 months after drug initiation, rituximab was associated with greater risk of pneumonia (HR 1.45, 95% CI 1.00-2.10; P = 0.047), COVID-19 (HR 1.87, 95% CI 1.49-2.33; P < 0.001), osteomyelitis (HR 2.42, 95% CI 1.11-5.31; P = 0.023), herpes simplex virus (HR 2.06, 95% CI 1.03-4.11; P = 0.037) and CMV (HR 1.63, 95% CI 1.07-2.49; P = 0.023) infections. CONCLUSIONS: Within the first 12 months after treatment, patients under rituximab experience an elevated risk of COVID-19, parasitic and CMV infections. Rituximab is associated with pneumonia, osteomyelitis and viral diseases even beyond the first year after therapy. Pneumococcal vaccine and suppressive antiviral therapy should be considered even 1 year following therapy. There is no signal for elevated risk of tuberculosis, hepatitis B virus reactivation, Pneumocystis jiroveci pneumonia and progressive multifocal leukoencephalopathy.

Isotretinoin and the risk of psychiatric disturbances: A global study shedding new light on a debatable story.

INTRODUCTION: Isotretinoin-related risk of depression and suicidal behavior is a topic of inconclusiveness. A crucial knowledge gap exists in defining the association of isotretinoin with other psychiatric comorbidities. OBJECTIVE: To evaluate the risk of psychiatric outcomes among patients with acne treated with isotretinoin versus oral antibiotics. METHODS: A global population-based retrospective cohort study enrolled 2 groups of patients with acne managed by isotretinoin (n = 75,708) and oral antibiotics (n = 75,708). Patients were compared regarding the risk of 9 psychiatric outcomes. RESULTS: Relative to those treated with oral antibiotics, patients prescribed isotretinoin experienced lower risk of depression (hazard ratio [HR], 0.90; 95% confidence interval [CI], 0.87-0.93; P < .001), but comparable risk of major depressive disorder (HR, 0.97; 95% CI, 0.92-1.03; P = .318). Risk of suicidal attempts was comparable between groups (HR, 0.97; 95% CI, 0.85-1.11; P = .663), despite the elevated risk of suicidal ideation in those under isotretinoin (HR, 1.41; 95% CI, 1.32-1.50; P < .001). Patients under isotretinoin had lower risk of post-traumatic stress disorder (HR, 0.75; 95% CI, 0.68-0.82; P < .001), anxiety (HR, 0.84; 95% CI, 0.82-0.87; P < .001), bipolar disorder (HR, 0.65; 95% CI, 0.59-0.72; P < .001), schizophrenia (HR, 0.60; 95% CI, 0.48-0.76; P < .001), and adjustment disorder (HR, 0.82; 95% CI, 0.77-0.87; P < .001). LIMITATIONS: Retrospective data collection. CONCLUSION: Isotretinoin confers lower risk of 6 psychiatric comorbidities and comparable risk of suicidal attempts.

Isotretinoin and the risk of inflammatory bowel disease and irritable bowel syndrome: A large-scale global study.

INTRODUCTION: Risk of inflammatory bowel disease under isotretinoin is a scope of a long-standing controversy. The burden of isotretinoin-related irritable bowel syndrome has not been investigated. OBJECTIVE: To evaluate the risk of Crohn's disease, ulcerative colitis (UC), and irritable bowel syndrome in patients with acne starting isotretinoin vs oral antibiotics treatment. METHODS: A global population-based retrospective cohort study assigned 2 groups of patients with acne initiating isotretinoin (n = 77,005) and oral antibiotics (n = 77,005). Comprehensive propensity-score matching was conducted. RESULTS: The lifetime risk of Crohn's disease (hazard ratio [HR], 1.05; 95% CI, 0.89-1.24; P = .583) and UC (HR, 1.13; 95% CI, 0.95-1.34; P = .162) was comparable between study groups, whereas the lifetime risk of irritable bowel syndrome was lower in isotretinoin-prescribed patients (HR, 0.82; 95% CI, 0.76-0.89; P < .001). In time-stratified analysis, isotretinoin-related risk of UC was significantly increased during the first 6 months following drug initiation (HR, 1.93; 95% CI, 1.29-2.88; P = .001), but decreased afterward to level the risk of the comparator group. The absolute risk difference within the first 6 months was clinically marginal (5.0 additional UC cases/10,000 patients starting isotretinoin; 95% CI, 2.5-7.7). LIMITATIONS: Retrospective data collection. CONCLUSION: Isotretinoin does not confer an elevated risk of Crohn's disease, whilst it might be associated with a slight and transient increase in UC risk.

Evaluating the risk of infections under interleukin 23 and interleukin 17 inhibitors relative to tumour necrosis factor inhibitors - A population-based study.

BACKGROUND: The risk of infections among patients with psoriasis undergoing interleukin (IL)-23 inhibitors (IL-23i) and IL-17 inhibitors (IL-17i) is yet to be exhaustively determined. OBJECTIVE: To assess the risk of infectious complications in patients with psoriasis managed by IL-23i and IL-17i with tumour necrosis factor inhibitors (TNFi) as a comparator. METHODS: A global cohort study comprised two distinct analyses comparing patients with psoriasis under different therapeutic modalities; (i) new users of IL-23i (n = 5272) versus TNFi (n = 5272) and (ii) new users of IL-17i (n = 15,160) versus TNFi (n = 15,160). Study groups were compared regarding the risk of 26 different infections. Propensity score matching was conducted to optimize between-group comparability. RESULTS: Patients under IL-23i had a lower risk of otitis media (HR, 0.66; 95% CI, 0.44-0.97), encephalitis (HR, 0.18; 95% CI, 0.04-0.78), herpes zoster (HZ; HR, 0.58; 95% CI, 0.41-0.82), hepatitis B virus (HBV) reactivation (HR, 0.24; 95% CI, 0.12-0.47), cytomegalovirus (HR, 0.25; 95% CI, 0.07-0.86), influenza (HR, 0.52; 95% CI, 0.38-0.71) and parasitic diseases (HR, 0.78; 95% CI, 0.64-0.95). IL-17i was associated with a decreased risk of pneumonia (HR, 0.76; 95% CI, 0.68-0.85), septicaemia (HR, 0.84; 95% CI, 0.72-0.97), upper respiratory tract infection (HR, 0.84; 95% CI, 0.77-0.92), HZ (HR, 0.79; 95% CI, 0.67-0.92), HBV (HR, 0.59; 95% CI, 0.46-0.76) and hepatitis C virus (HR, 0.71; 95% CI, 0.57-0.88) reactivation, cytomegalovirus (HR, 0.58; 95% CI, 0.36-0.93), Epstein-Barr virus (HR, 0.38; 95% CI, 0.19-0.75), influenza (HR, 0.70; 95% CI, 0.61-0.81) and parasitic diseases (HR, 0.80; 95% CI, 0.72-0.88). CONCLUSION: Compared with TNFi, IL-23i and IL-17i are associated with decreased risk of several infectious diseases. These agents might be preferred in patients with susceptibility to infections.

Research in practice: Diet and microbiome in autoimmune diseases.

The incidence of autoimmune diseases in industrialized countries is constantly increasing over past decades. These diseases lead to increased mortality and persistent reduction in quality of life of the patients, posing a severe medical burden. Treatment of autoimmune diseases is often based on unspecific immune suppression, increasing the risk of infectious diseases as well as cancer manifestation. Pathogenesis of autoimmune conditions is complex and includes not only genetic factors, but also environmental influence, which is considered to be the reason for the rise of incidence of autoimmune diseases. Environmental factors comprise numerous elements, such as infections, smoking, medication, diet etc., which can either promote or prevent the onset of autoimmunity. However, the mechanisms of environmental influence are complex and for this moment not clearly understood. Deciphering of these interactions could enhance our comprehension of autoimmunity and provide some novel treatment options for the patients.

The G protein-coupled receptor 15 (GPR15) regulates cutaneous immunology by maintaining dendritic epidermal T cells and regulating the skin microbiome.

The G protein-coupled receptor 15 (GPR15) regulates homing of different T-cell populations into the gut, thus, preserving tissue homeostasis. Its potential role in the preservation of homeostasis on other body interfaces, including the skin, is less well understood. We addressed the impact of GPR15 on cutaneous T-cell populations and the skin microbiome under steady-state conditions. Genetic deficiency in GPR15 substantially altered the composition of skin-resident T-cell populations. Precisely, dendritic epidermal T cells were almost absent in the epidermis of Gpr15-/- mice. The niche of dendritic epidermal T cells in the epidermis was, instead, populated by αß TCR+ T cells. These changes were associated with shifts in the skin microbiota in Gpr15-/- mice. Collectively, our results uncover a role of GPR15 in the regulation of the cutaneous immune system and, thus, highlight the receptor as important general regulator of tissue homeostasis of exterior body interfaces.

Evidence for a role of extracellular heat shock protein 70 in epidermolysis bullosa acquisita.

Heat shock protein 90 (Hsp90) and Hsp70 are chaperones implicated in different inflammatory disorders, given their property to impact innate and adaptive immune responses. Here, we determined the so far unknown role of extracellular Hsp70 in epidermolysis bullosa acquisita (EBA), an anti-type VII collagen autoantibody-mediated blistering dermatosis. The in vivo pathophysiological relevance of extracellular Hsp70 was demonstrated in an anti-type VII collagen antibody transfer-induced EBA mouse model in which elevated blood levels of this chaperone were recorded. We found that Hsp70-treated mice had a more intense clinical disease severity compared to controls that were paralleled by increased levels of cutaneous matrix metalloproteinase 9 and plasma hydrogen peroxide. The latter finding was confirmed in an independent reactive oxygen species release assay using EBA-specific immune complexes combined with recombinant Hsp70. Finally, cell culture experiments using human naive peripheral blood mononuclear cells (PBMC) revealed that extracellular Hsp70 stimulated the secretion of the T cell-derived pro-inflammatory cytokines IL-6 and IL-8. This work extends knowledge about the role of Hsps in autoimmune bullous diseases, suggesting that extracellular Hsp70 represents a pathophysiological factor and potential treatment target in EBA.

Association between TH2 Cytokine Gene Polymorphisms and Risk of Bullous Pemphigoid.

BACKGROUND: T-helper 2 (Th2)-associated cytokines are involved in the pathogenesis of bullous pemphigoid (BP), an autoimmune skin disease. Increased expression of Th2 cytokines such as interleukin-4 (IL-4), IL-5, IL-6, IL-10, and IL-13 have been observed in serum, skin biopsies and/or blister fluid. This study aimed to uncover a possible association between Th2 cytokine genetic variations and susceptibility to BP. METHODS: In a cohort study, blood samples of BP patients and controls were obtained and variations in IL-4 (rs2243250 and rs2070874), IL-4R (rs1805010), IL-5 (rs2069812), IL-6 (rs1800795), IL-10 (rs1800896, rs1800871, and rs1800872), and IL-13 (rs1800925 and rs20541) were genotyped by PCR-RFLP assays. Furthermore, quantitative expression levels of IL-13 gene were evaluated by real-time RT-PCR analysis. RESULTS: Among the studied variations, a significantly higher frequency of the C-allele was observed in IL-13 gene variation (rs1800925) in the healthy individuals than BP patients. This may indicate a protective effect of C-allele on predisposition to BP. Considering individuals carrying polymorphic genotypes compared to wild genotype, the minor G-allele of IL-4R rs1805010 and A-allele of IL-13 rs20541 had a promotive and protective effect, respectively, on predisposing to the development of BP. No significant difference in IL-13 mRNA expression was detected between BP patients and healthy individuals. CONCLUSIONS: Our results indicate that IL-13 rs1800925 variation may be a protective genetic marker for the development of BP. Given this preventive effect against BP, therapeutic strategies could potentially be developed interfering with the functions of IL-13 cytokine, which seems to be integral in the pathogenesis of eosinophilic inflammatory disorders, such as BP.

DNA chip-based diagnosis of onychomycosis and tinea pedis.

BACKGROUND AND OBJECTIVES: Onychomycosis (OM) and tinea pedis (TP) are common fungal infections. Currently, diagnosis is based on direct microscopy and culture that have a low to moderate sensitivity and/or require up to 3-4 weeks until results are obtained. PCR techniques have emerged for the diagnosis of fungal infections, but little is known about their sensitivity and specificity in diagnosing. Here, we compared the diagnostic value of a DNA-chip technology, that detects 56 fungal pathogens, in a single-center prospective diagnostic study with microscopy and culture in suspected OM/TP. PATIENTS AND METHODS: Microscopy, culture and DNA microarray assays were performed on scraping material from patients with suspected OM (n = 67) or TP (n = 73). To test whether swabs can be used as an alternative for scraping, PCR yields were compared in a further 13 patients with OM and 11 patients with TP. RESULTS: DNA microarrays had the highest sensitivity. Combination of DNA-chip technology with microscopy further increased the sensitivity, and results from this combined laboratory diagnosis can be obtained within 24 hours. Comparison of sampling techniques (scraping, dry or wet swab) for DNA-chip assays showed similar results in suspected OM or TP. CONCLUSIONS: DNA-chip technology shows high sensitivity for OM and TP diagnosis, especially when combined with microscopy.

DNA-Chip-basierte Diagnose der Onychomykose und Tinea pedis.

HINTERGRUND UND ZIELE: Onychomykose (OM) und Tinea pedis (TP) sind häufige Pilzinfektionen der Haut. Aktuell basiert die Diagnose vornehmlich auf mikroskopischem Direktnachweis und/oder Kultur. Beide Methoden haben jedoch eine geringe bis mäßige Sensitivität und benötigen teilweise mehrere Wochen, bis endgültige Laborergebnisse vorliegen. Um die Diagnose kutaner Pilzinfektionen zu verbessern, wurden PCR-basierte Methoden entwickelt. Hier haben wir hier die Sensitivität und Spezifität einer Chip-basierten Multiplex-PCR mit mikroskopischen Direktnachweis und verglichen. PATIENTEN UND METHODIK: In einer monozentrischen, prospektiven Studie wurden bei Patienten mit Verdacht auf OM (n  =  67) oder TP (n  =  73) Schuppenpräparate entnommen und mittels mikroskopischem Direktnachweis, Kultur und DNA-Chip-Technologie der Erregernachweis durchgeführt. In einem weiteren Ansatz wurde überprüft, ob Abstriche als Alternative zur Entnahme eines Schuppenpräparates verwendet werden können. Hierfür wurden 24 weitere OM/TP-Patienten rekrutiert und die Ergebnisse der DNA-Chip-Technologie aus Abstrichen mit denen aus den Schuppenpräparaten verglichen. ERGEBNISSE: Im Vergleich aller Methoden hatte die DNA-Chip-Technologie die höchste Sensitivität, eine Kombination von DNA-Chip-Technologie mit mikroskopischem Direktnachweis erhöhte dies weiter. Ergebnisse dieser kombinierten Labordiagnostik sind innerhalb von 24 Stunden verfügbar. Der Vergleich der Probenentnahmetechniken (Abstrich beziehungsweise Schuppenpräparat) zeigte vergleichbare Ergebnisse. SCHLUSSFOLGERUNGEN: Die molekulare Diagnostik (mittels DNA-Chip-Technologie) hat eine hohe Sensitivität für die OM- und TP-Diagnostik, insbesondere in Kombination mit dem mikroskopischen Direktnachweis.

The risk of COVID-19 in patients with bullous pemphigoid and pemphigus: A population-based cohort study.

BACKGROUND: The burden of COVID-19 in patients with bullous pemphigoid (BP) and pemphigus is yet to be evaluated. OBJECTIVE: To assess the risks of COVID-19 and COVID-19-associated hospitalization and mortality in patients with BP and pemphigus and to delineate determinants of severe COVID-19 illness among these patients. METHODS: A population-based cohort study compared COVID-19 and its complications in patients with BP (n = 1845) and pemphigus (n = 1236) with age-, sex-, and ethnicity-matched control subjects. RESULTS: The risks of COVID-19 (hazard rate [HR], 1.12; 95% confidence interval [CI], 0.72-1.73; P = .691) and COVID-19-associated hospitalization (HR, 1.58; 95% CI, 0.84-2.98; P = .160) was comparable between patients with BP and controls. The risk of COVID-19-associated mortality was higher among patients with BP (HR, 2.82; 95% CI, 1.15-6.92; P = .023). The risk of COVID-19 (HR, 0.81; 95% CI, 0.44-1.49; P = .496), COVID-19-associated hospitalization (HR, 1.41; 95% CI, 0.53-3.76; P = .499), and COVID-19-associated mortality (HR, 1.33; 95% CI, 0.15-11.92; P = .789) was similar in patients with pemphigus and their controls. Systemic corticosteroids and immunosuppressants did not predispose COVID-19-positive BP and pemphigus patients to a more severe illness. LIMITATIONS: Retrospective data collection. CONCLUSIONS: Patients with BP experience increased COVID-19-associated mortality and should be monitored closely. Maintaining systemic corticosteroids and immunosuppressive adjuvant agents during the pandemic is not associated with worse outcomes.