Role of Human Leukocyte Antigen Class II in Antibody-Mediated Skin Disorders.

HLA class II molecules are key factors determining susceptibility to autoimmune disorders, and their role in immune-mediated skin conditions such as psoriasis has been extensively investigated. However, there is currently little understanding of their role in antibody-mediated skin diseases such as autoimmune blistering disorders. We researched the available literature using PubMed to narratively review the current knowledge on HLA associations in antibody-mediated blistering skin pathologies. Our results summarized the risk alleles that are identified in the literature, together with certain known protective alleles: in the pemphigus group, alleles HLA-DQB1*0503 and HLA-DRB1*0402 are most commonly associated with disease; in the pemphigoid group, the most studied allele is HLA-DQB1*0301; in epidermolysis bullosa acquisita, few genetic studies are available; in dermatitis herpetiformis, the association with haplotypes HLA-DQ2 and HLA-DQ8 is strongly established; finally, in linear IgA bullous disease, specific HLA alleles may be responsible for pediatric presentations. Our current pathogenic understanding of this group of disorders assigns a key role to predisposing HLA class II alleles that are able to bind disease autoantigens and therefore stimulate antigen-specific autoreactive T cells. The latter engage B lymphocytes that will produce pathogenic autoantibodies. The distribution of HLA alleles and their disease associations are variable across demographics, and an in-depth pathogenetic understanding is needed to support associations between HLA alleles and disease phenotypes. Additionally, in a personalized medicine approach, the identification of HLA alleles associated with the risk of disease may become clinically relevant in identifying susceptible subjects that should avoid exposure to known triggers, such as medication, when possible.

The Impact of the Initial Phase of the COVID-19 Pandemic on Patients With Autoimmune Bullous Diseases.

Introduction The follow-up of patients with autoimmune bullous diseases (AIBDs) was temporarily interrupted during the initial phase of the COVID-19 pandemic due to restrictions in healthcare services, given the high contagiousness and rapid spread of SARS-CoV-2. Our objective was to assess the impact of the initial phase of the COVID-19 pandemic on the treatments and disease activity of AIBD patients. Methods We conducted a telephone survey of patients with AIBDs who had been regularly followed up in our hospital prior to the onset of the pandemic. A structured questionnaire that we designed was used. This questionnaire comprised questions examining the following issues between March and June of 2020: patients' follow-up, treatment, COVID-19 infection status, and changes in disease activity. Results Thirty-nine patients were included in the study. Among those, 26 (66.7%) were immunosuppressed. The frequency of follow-up for 37 patients (94.9%) changed significantly (p<0.001): 28 patients (71.8%) did not visit the hospital, and 26 of them (92.9%) did not communicate at all. The treatment for 10 patients (25.6%) was altered, either by their physician or by themselves. Disease activity reactivated in patients who altered their own treatments. There was only one patient (2.6%) who contracted COVID-19. Conclusions Documenting this period revealed that some patients were negatively impacted by the pandemic initially. The most significant contributing factor was the interruption of patient-physician communication.

Autoantibody Profile of a Cohort of 54 Italian Patients with Linear IgA Bullous Dermatosis: LAD-1 Denoted as a Major Auto-antigen of the Lamina Lucida Subtype.

Linear IgA bullous dermatosis (LABD) is characterized by presence of multiple IgA autoantibodies, and a comparatively lesser number of IgG antibodies, directed against different hemidesmosomal antigens. The main autoantigens are LAD-1, LABD-97, BP180 and BP230, type VII collagen and laminin 332. We retrospectively studied the serology of 54 Italian patients with LABD using enzyme-linked immunosorbent assay (ELISA), immunoblotting assay, and indirect immunofluorescence on monkey oesophagus and salt-split skin. Among these, indirect immunofluorescence of salt-split skin elicits the greatest sensitivity. Sixty-three percent of the sera were observed to be positive, with a lamina lucida pattern observed in 48%, a sub-lamina densa pattern in 2% and a mixed pattern in 13% of the cases. IgA reactivity to LAD-1 on immunoblotting was found in 52% of sera, to BP180-NC16A by ELISA in 32% and to BP230 in 26%. Only 17% of patients possessed circulating IgG autoantibodies. LAD-1 was determined to be a major autoantigen of the lamina lucida subtype. Combined serological assays demonstrated a high sensitivity (82%), suggesting that this approach could support diagnosis when a biopsy is not feasible or direct immunofluorescence results are negative.

Collagen XVII Processing and Blistering Skin Diseases.

Collagen XVII (COL17) is a hemidesmosomal transmembrane protein in the skin, which, in several autoimmune blistering skin diseases, may be targeted by autoantibodies. In addition, loss-of-function mutations in the COL17A1 gene induce a subtype of junctional epidermolysis bullosa. The extracellular domain of COL17 can be physiologically cleaved from the cell surface by ADAM family proteins in a process known as ectodomain shedding. COL17 ectodomain shedding is thought to be associated with the migration and proliferation of keratinocytes. Furthermore, the C-terminal cleavage of COL17 may be associated with basement membrane formation. COL17 can be targeted by various proteases, including MMP9, neutrophil elastase, plasmin and granzyme B, which may be associated with blister formation in pemphigoid diseases. Interestingly, cleavage of COL17 may induce neoepitopes on the proteolysed fragments, and such induction is associated with dynamic structural changes. This review summarizes the current understanding of cleavage of COL17, and how such cleavage relates to blistering skin diseases.

Dermatitis herpetiformis-like Linear IgA bullous disease in a Filipino

@#INTRODUCTION: Linear IgA bullous disease (LABD) is a rare autoimmune blistering disease characterized by subepithelial bullae and linear IgA deposition along the basement membrane zone of the epidermis. Lesions present as pruritic papulovesicles and tense bullae which may coalesce forming annular or polycyclic urticarial plaques with blistering on the edge of the lesions forming the classic “string of pearls” sign. Lesions may affect the face, trunk, and extensor extremities. Incidence rates range from 0.5 to 2.3 cases per million individuals per year. Due to its rare occurrence, there are only a fewdocumented reports on cases of LABD, particularly in the Filipino population. CASE REPORT: A 33 year-old Filipino female consulted because of a 3-week history of severely pruritic vesicles and crusts on the face, trunk, and arms. Patient noted no gastrointestinal symptoms on consultation. Skin punch biopsy revealed subepidermal blisters with collection of neutrophils at the dermal papillae. Direct immunofluorescence showed strong (+2) deposits of linear IgA at the dermo- epidermal junction in perilesional skin thus validating the diagnosis. The patient’s serum was negative for IgA anti-tissue transglutaminase and IgA antiendomysial antibodies. Patient was treated with topical corticosteroids and Dapsone 50 mgs OD with remarkable improvement. CONCLUSION: Linear IgA bullous disease has very few reported cases especially in the Philippine setting. Dapsone is considered the first-line treatment. The disease may persist for a decade or longer, and relapses may occur. Careful history-taking accompanied by the histological, immunofluorescence, and serological findings must be done to ensure proper treatment and good prognosis.

Childhood linear IgA bullous disease induced by trimethoprim-sulfamethoxazole.

BACKGROUND: Linear IgA bullous disease (LABD) is a rare mucocutaneous autoimmune subepidermal blistering disease that can affect children mostly of pre-school age. As many as two-thirds of LABD are related to drug ingestion, particularly certain antibiotics, non-steroidal anti-inflammatory drugs and diuretics. MAIN OBSERVATION: We describe a 3-year-old boy who presented a CMV infection followed by LABD induced by trimtheporim-sulfametoxazole. To our knowledge, this is the first reported case of trimethoprim-sulfamethoxazole that was confirmed by a rechallenge. CONCLUSIONS: Most cases of drug-induced LABD are patients being treated with multiple systemic drugs that could induce the LABD. In the lack of suitable alternative treatment, the identification of the causative drug can be achieved by a rechallenge under close medical surveillance.