Pathogenesis Of Bullous Pemphigoid Research Articles

Frequency and Correlation of Peripheral and Tissue Eosinophilia with Clinical Manifestations in Patients with Bullous Pemphigoid.

Bullous pemphigoid (BP) is an autoimmune disease involving the sub-epidermal layer. Eosinophilia may play a role in the pathogenesis of BP. We aimed to investigate the correlation between dermal or peripheral eosinophilia with clinical presentations in patients with BP. This cross-sectional study was conducted on 108 BP patients from January 2010 to September 2019. Clinical data were recovered. Skin biopsies were re-evaluated, and the Bullous Pemphigoid Disease Area Index (BPDAI) severity score was calculated. Finally, the relationship between clinical features of BP and dermal or peripheral eosinophilia was analyzed. A total number of 108 patients were included in this study. Thirty-five were excluded due to our exclusion criteria. Finally, data from 73 patients were analyzed. Fifty-seven point five percent of the population was female. There was a significant direct correlation (r = 0.33) between BPDAI severity score and tissue eosinophilia (P = 0.03). No significant relationship was found between BPDAI severity score and peripheral eosinophilia (P = 0.52). There were significant positive correlations between tissue eosinophilia with absolute serum eosinophil count (P = 0.002; r = 0.49) and percentage (P < 0.0001; r = 0.89). This study revealed significant relationships between tissue eosinophilia and BP severity. These findings could be useful in clinical practice. The possible role of eosinophils in BP clinical features should be considered as a promising help for better diagnosis and treatment.

Anti-IL-17 monoclonal antibodies and bullous pemphigoid: treatment or causal agents? A case series and review of the literature.

Bullous pemphigoid (BP) is an autoimmune bullous disease, typically affecting the elderly, characterized by the production of autoantibodies directed against structural components of the dermal-epidermal junction. An association between BP and psoriasis has been described several times, but the mechanisms underlying this association have yet to be clearly defined. The pathophysiological mechanism underlying psoriasis may be implicated in the pathogenesis of BP, as psoriasis precedes BP in most cases; in particular, a promoting role has been hypothesized by biologic therapies, which may induce a switch from a T helper 1 (TH1)/TH17-dominant cytokine milieu, typical of patients with psoriasis, to a TH2-dominant one, typical of patients with BP. IL-17 inhibitors, in particular, have also been successfully used to treat BP in patients with psoriasis. The use of these drugs in these patients has been based on in vitro studies. However, cases of new-onset BP or relapses of BP already diagnosed in patients with psoriasis treated with biologic drugs have also been reported, and they occurred mainly in patients on anti-TNF drugs, yet very few cases with anti-IL-17A drugs have been described. We hereby describe two cases of new-onset BP in two patients treated with anti-IL-17 drugs for psoriasis.

Serum Biomarkers in Bullous Pemphigoid: A Systematic Review.

Bullous pemphigoid (BP) is the most common type of subepidermal blistering disease, usually observed in the elderly population, with a mean age of presentation between 66 and 83 years. BP is a psychosocially ladened disease, with many patients experiencing negative body image, social isolation, and depression. The identification and validation of biomarkers in BP may further the understanding of disease pathogenesis, provide objective measures in assessing efficacy in clinical trials, and identify new targets for targeted therapy. Two databases (Medline and Embase) were searched from database inception to September 2023. All published articles reporting on biomarker levels of BP patients in serum compared to healthy controls were included. A total of 877 unique articles were identified, resulting in the inclusion of 62 case-control studies reporting on a total of 1837 patients and 140 unique biomarkers. Biomarkers were categorized into T-cell mediated, B-cell mediated, innate immune system, and coagulation cascade pathway. The most notable biomarkers identified include increases in anti-BP180/230 immunoglobulin (Ig)G/E, total IgE, TNF-α, B-cell activating factor, interleukin-31, eosinophil cationic protein, MMP-9, and coagulation cascade biomarker levels. The results of this review provide the greatest support for a role of anti-BP180/230 autoantibodies, Th2 cells, eosinophils, and the coagulation cascade in the pathogenesis of BP. The pathogenesis of BP has an underlying autoimmune etiology centred around the production of autoantibodies against BP180/230, but increased Th2, eosinophil and coagulation cascade activity may be contributory.

Single-cell transcriptomics analysis of bullous pemphigoid unveils immune-stromal crosstalk in type 2 inflammatory disease

Bullous pemphigoid (BP) is a type 2 inflammation- and immunity-driven skin disease, yet a comprehensive understanding of the immune landscape, particularly immune-stromal crosstalk in BP, remains elusive. Herein, using single-cell RNA sequencing (scRNA-seq) and in vitro functional analyzes, we pinpoint Th2 cells, dendritic cells (DCs), and fibroblasts as crucial cell populations. The IL13-IL13RA1 ligand–receptor pair is identified as the most significant mediator of immune-stromal crosstalk in BP. Notably, fibroblasts and DCs expressing IL13RA1 respond to IL13-secreting Th2 cells, thereby amplifying Th2 cell-mediated cascade responses, which occurs through the specific upregulation of PLA2G2A in fibroblasts and CCL17 in myeloid cells, creating a positive feedback loop integral to immune-stromal crosstalk. Furthermore, PLA2G2A and CCL17 contribute to an increased titer of pathogenic anti-BP180-NC16A autoantibodies in BP patients. Our work provides a comprehensive insight into BP pathogenesis and shows a mechanism governing immune-stromal interactions, providing potential avenues for future therapeutic research.

High serum total IgE levels correlate with urticarial lesions and IgE deposition in perilesional skin of bullous pemphigoid patients: An observational study.

Background In the pathophysiology of bullous pemphigoid, besides IgG, there has been evidence that supports the role of IgE antibodies. However, there have been no studies to evaluate total serum IgE levels or detect IgE deposits in the skin of Vietnamese patients. Aim To analyse the association between IgE levels in the serum and disease severity as well as eosinophils and IgE basement membrane zone (BMZ) deposition in Vietnamese bullous bullous pemphigoid patients. Methods A single-centre observational research on 35 newly diagnosed and untreated bullous bullous pemphigoid patients. Total serum IgE levels were analysed using enzyme-linked immunosorbent assay (ELISA). For controls, we collected sera of 30 pemphigus patients and 30 elderly patients with pruritus. Perilesional skin biopsies underwent direct immunofluorescence (DIF) staining, with biopsies of pemphigus patients as controls. Results Elevated total serum IgE was observed in 60% of bullous pemphigoid patients, the percentage in the pemphigus group and pruritus group was 20% and 40%, respectively. The mean total serum IgE level among the bullous pemphigoid group was higher than that of the pemphigus group (123.3 ± 102.4 IU/mL vs. 64.3 ± 45.1 IU/mL, p = 0.010). Total serum IgE levels of bullous pemphigoid patients correlated with higher eosinophil counts (r = 0.61; p = 0.018) and urticaria/erythema (U/E) Bullous Pemphigoid Disease Area Index (BPDAI) score (r = 0.50; p = 0.035). Among 35 bullous pemphigoid patients, 5 patients showed positive IgE DIF staining, accounting for 14.3%. Higher serum IgE levels correlated with the deposition of IgE in patients' perilesional skin (p = 0.037). Limitations Due to the rarity of bullous pemphigoid, the effect of the COVID-19 pandemic, and self-treatment issues in Vietnam, we could not recruit a larger number of participants. Conclusions Total serum IgE values correlated with urticarial lesions and IgE deposition in perilesional skin of Vietnamese bullous pemphigoid patients. IgE autoantibodies present in the skin of bullous pemphigoid patients support the role of IgE in bullous pemphigoid pathogenesis.

Diacron-Reactive Oxygen Metabolites Levels Are Initially Elevated in Patients with Bullous Pemphigoid

Reactive oxygen species (ROS) are involved in the pathogenesis of bullous pemphigoid (BP), but this involvement has not been fully elucidated. In this study, to further elucidate the pathogenic role of ROS in BP, we examined the results of the diacron-reactive oxygen metabolite (d-ROMs) test and the biological antioxidant potential test for 16 BP patients who visited our hospital before being treated with systemic corticosteroids. In the BP patients, the average d-ROMs levels, expressed in Carratelli units (U.CARR), were significantly reduced at 1 month of treatment (from 335.6 ± 40.3 U.CARR to 224.7 ± 61.6 U.CARR, P<0.001). Bullous Pemphigoid Disease Area Index (erosions/blisters) scores correlated with d-ROMs levels (r=0.51), suggesting that those levels reflect the disease severity. We also performed staining of 3,5-dibromotyrosine (DiBrY) in skin tissues. DiBrY is expected to be a marker of tissue damage related to inflammation and allergies. The DiBrY was stained in infiltrated cells around the dermis, throughout the blister fluid, and at the basement membrane within the blister. It is considered that tissue destruction caused by the myeloperoxidase released from neutrophils and by eosinophil peroxidase released from eosinophils is involved in blister formation. The results suggest that ROS play a role in BP.

Efficacy of omalizumab for the treatment of bullous pemphigoid: Spanish multicentre real-world experience.

Bullous pemphigoid (BP) is the most common autoimmune blistering disease. Most patients are older and have associated multiple comorbidities. Topical and systemic corticosteroids are considered the first-line treatment for BP, and immunosuppressants are used as steroid-sparing treatments. However, both have side-effects and contraindications, which are even more common in this older population. New treatments targeting interleukins and receptors related to BP pathogenesis have been proposed to decrease these side-effects while achieving equal or better effectiveness and response rates. Omalizumab is a monoclonal antibody that targets IgE and has been proposed for the treatment of BP due to the evidence that IgE autoantibodies play an essential role in BP pathogenesis. To assess the efficacy and safety of omalizumab for the treatment of BP. We carried out a multicentre, retrospective, observational study including patients diagnosed with BP who received omalizumab for ≥ 3 months from 15 tertiary hospitals in Spain. IgE levels prior to treatment were measured, and we evaluated the possible correlation with clinical response. We excluded patients treated with omalizumab for < 3 months, as we consider this duration to be insufficient for a comprehensive assessment of its efficacy. To evaluate the effectiveness of the treatment, we used the percentage of body surface area improvement. We included 36 patients. The vast majority had associated multiple comorbidities, and all patients had used other systemic therapies apart from corticosteroids before omalizumab. In total, 83% experienced some kind of treatment response and 42% of all patients treated achieved complete response. We did not find any correlation between higher IgE levels and a better response (P = 0.2). All patients tolerated omalizumab without reported side-effects. Omalizumab is a good therapeutic alternative for BP as it provided clinical response in most patients, and nearly one-half of the cases achieved complete response. It showed no side-effects, which is crucial in older patients with BP.

Advancements in Bullous Pemphigoid Treatment: A Comprehensive Pipeline Update.

Bullous pemphigoid (BP) is a common autoimmune bullous disease affecting mainly the elderly, with rising incidence due to increased life expectancy. This disease is characterized by tense bullous lesions on normal or erythematous skin, accompanied by pruritus. BP pathogenesis involves autoantibodies against hemidesmosomal proteins BP180 and BP230, leading to detachment at the dermo-epidermal junction as well as blister formation. BP is associated with coexisting comorbidities and drug exposure, and its management often requires high doses or chronic use of systemic glucocorticoids, posing risks of adverse effects. This review focuses on novel treatment options for BP, exploring therapies targeting different immune pathways. Rituximab, a CD20 monoclonal antibody, depletes B-lymphocytes and has shown efficacy in severe cases. Dupilumab, targeting interleukin (IL)-4 receptor α and thus blocking IL-4 and IL-13, downregulates type 2 helper (Th2) responses and has demonstrated promising results. Targeting eosinophil-related molecules using bertilimumab and AKST4290 has yielded positive results in clinical trials. Omalizumab, an immunoglobulin (Ig)E antibody, can reduce disease severity and allows corticosteroid tapering in a number of cases. Complement inhibitors such as nomacopan and avdoralimab are being investigated. IL-17 and IL-23 inhibitors such as secukinumab and tildrakizumab have shown potential in a limited number of case reports. Neonatal Fc receptor antagonists such as efgartigimod are under investigation. Additionally, topical therapies and Janus kinase inhibitors are being explored as potential treatments for BP. These novel therapies offer promising alternatives for managing BP, with potential to improve outcomes and reduce high cumulative doses of systemic corticosteroids and related toxicities. Further research, including controlled clinical trials, is needed to establish their efficacy, safety, and optimal dosing regimens for BP management.

Targeting type 2 inflammation in bullous pemphigoid: current and emerging therapeutic approaches.

Bullous pemphigoid (BP) is one of the most common autoimmune bullous diseases and mainly affects an elderly population with multi-morbidity. Due to the frailty of many BP patients, existing treatment options are limited. The blisters associated with BP result from IgG and IgE autoantibodies binding to the central components of hemidesmosome, BP180, and BP230, stimulating a destructive inflammatory process. The known characteristic features of BP, such as intense pruritus, urticarial prodrome, peripheral eosinophilia, elevated IgE, as well as recent expanding evidence from in vitro and in vivo studies implicate type 2 inflammation as an important driver of BP pathogenesis. Type 2 inflammation is an inflammatory pathway involving a subset of CD4+ T cells that secrete IL-4, IL-5, and IL-13, IgE-secreting B cells, and granulocytes, such as eosinophils, mast cells, and basophils. It is believed that effectors in type 2 inflammation may serve as novel and effective treatment targets for BP. This review focuses on recent understandings of BP pathogenesis with a particular emphasis on the role of type 2 inflammation. We summarize current clinical evidence of using rituximab (B-cell depletion), omalizumab (anti-IgE antibody), and dupilumab (anti-IL-4/13 antibody) in the treatment of BP. The latest advances in emerging targeted therapeutic approaches for BP treatment are also discussed.

Dietary habits in Japanese patients with bullous pemphigoid: low intake of retinol.

Bullous pemphigoid (BP) is an autoimmune subepidermal blistering disease. Dietary habits may modulate the pathogenesis of BP. We evaluated dietary habits in Japanese patients with BP and compared their results to those of age- and sex-matched healthy controls. We also examined the relationship between dietary habits versus IgG anti-BP180NC16A antibody or parameters of BP disease area index (BPDAI); cutaneous blisters/erosions, cutaneous urticaria/erythema, and mucosal blisters/erosions. Dietary habits were assessed by the validated, Brief-type self-administered Diet History Questionnaire. Severity of disease was assessed with BPDAI. Patients with BP showed a lower intake of retinol (vitamin A1) and beverages, and a higher intake of seasoning/spices, compared to controls. The bivariate and multivariable logistic regression analysis showed that BP was associated with a low intake of retinol and beverages. There were no significant correlations between IgG anti-BP180NC16A antibody levels and intake of nutrients/foods. The BPDAI score for cutaneous blisters/erosions significantly positively correlated with intake of carbohydrate and negatively with intake of retinol, vitamin A, animal fat, cholesterol, phosphorus, and vitamin B2. The BPDAI score for cutaneous urticaria/erythema significantly negatively correlated with intake of vitamin A. BP patients with mucosal blisters/erosions had a higher intake of cholesterol, n-6 polyunsaturated fatty acid, and eggs, and lower intake of seasoning/spices, compared to patients without BP. The supplementation of vitamin A might have prophylactic and/or therapeutic effects on BP.

Eosinophils, Basophils, and Neutrophils in Bullous Pemphigoid.

Bullous pemphigoid (BP) is an autoimmune blistering skin disease, of which the incidence has increased in recent years. BP is characterized by circulating IgG and IgE autoantibodies against the hemidesmosomal proteins BP180 and BP230. Although autoantibodies trigger inflammatory cascades that lead to blister formation, effector cells and cell-mediated autoimmunity must also be considered as important factors in the pathogenesis of BP. The aim of this review is to outline the current knowledge on the role of eosinophils, basophils, and neutrophils in BP.

Localized Bullous Pemphigoid

A man in his 80s presented with a pruritic, focally ulcerated pink plaque with overlying blisters on the left lateral thigh (Figures 1 and 2). This had been the site of an excision 9 months earlier. Over time, pruritic vesicles and bullae developed at the surgical site. Punch biopsies showed a subepidermal bulla with extensive eosinophilic infiltrate on histopathology and linear deposition of C3 and immunoglobulin G (IgG) at the basement membrane zone on direct immunofluorescence, confirming the diagnosis of localized bullous pemphigoid (BP).Figure 2Close-up view of vesicles and bullae at the periphery.View Large Image Figure ViewerDownload Hi-res image Download (PPT) BP is a subepidermal autoimmune blistering disease caused by autoantibodies to hemidesmosome proteins BP180 (BP antigen 2) or BP230 (BP antigen 1). Classically, patients present with pruritic urticarial papules and plaques and tense vesicles and bullae. Diagnosis is made by examination of the tissue and direct immunofluorescence, which show a subepidermal accumulation of eosinophils and linear deposition of IgG and/or C3 in an n-serrated pattern along the basement membrane zone, respectively. Enzyme-linked immunosorbent assay (ELISA) for autoantibodies to the NC16a domain of BP180 and to BP230 is supportive, and anti-BP180-NC16a ELISA may aid in monitoring disease activity during treatment.1Schmidt E. Zillikens D. Pemphigoid diseases.Lancet. 2013; 381: 320-332https://doi.org/10.1016/S0140-6736(12)61140-4Abstract Full Text Full Text PDF PubMed Scopus (705) Google Scholar,2Feliciani C. Joly P. Jonkman M.F. et al.Management of bullous pemphigoid: the European Dermatology Forum consensus in collaboration with the European Academy of Dermatology and Venereology.Br J Dermatol. 2015; 172: 867-877https://doi.org/10.1111/bjd.13717Crossref PubMed Scopus (233) Google Scholar Most cases of BP are generalized. Rarely, it is localized, usually to sites of previous skin injury, surgery, radiation, or venous insufficiency.3Ständer S. Kasperkiewicz M. Thaçi D. et al.Prevalence and presumptive triggers of localized bullous pemphigoid.J Dermatol. 2021; 48: 1257-1261https://doi.org/10.1111/1346-8138.15912Crossref PubMed Scopus (4) Google Scholar Although the pathophysiology of localized BP is not well understood,4Danescu S. Chiorean R. Macovei V. Sitaru C. Baican A. Role of physical factors in the pathogenesis of bullous pemphigoid: case report series and a comprehensive review of the published work.J Dermatol. 2016; 43: 134-140https://doi.org/10.1111/1346-8138.13031Crossref PubMed Scopus (39) Google Scholar topical steroids are first-line therapy and are generally effective.2Feliciani C. Joly P. Jonkman M.F. et al.Management of bullous pemphigoid: the European Dermatology Forum consensus in collaboration with the European Academy of Dermatology and Venereology.Br J Dermatol. 2015; 172: 867-877https://doi.org/10.1111/bjd.13717Crossref PubMed Scopus (233) Google Scholar Our patient was treated with topical clobetasol 0.05% ointment twice daily for 3 weeks with excellent results, and subsequent use as needed to maintain clearance. The authors report no competing interests.

Adaptive and innate immune pathogenesis of bullous pemphigoid: A review.

Bullous pemphigoid (BP) is an autoimmune blistering disease that primarily affects elderly individuals. The presentation of BP is heterogeneous, typically manifesting as microscopic subepidermal separation with a mixed inflammatory infiltrate. The mechanism of pemphigoid development is unclear. B cells play a major role in pathogenic autoantibody production, and T cells, type II inflammatory cytokines, eosinophils, mast cells, neutrophils, and keratinocytes are also implicated in the pathogenesis of BP. Here, we review the roles of and crosstalk between innate and adaptive immune cells in BP.

Bullous pemphigoid: The role of type 2 inflammation in its pathogenesis and the prospect of targeted therapy.

Bullous pemphigoid (BP) is an autoimmune disease that mainly occurs in the elderly, severely affecting their health and life quality. Traditional therapy for BP is mainly based on the systemic use of corticosteroids, but long-term use of corticosteroids results in a series of side effects. Type 2 inflammation is an immune response largely mediated by group 2 innate lymphoid cells, type 2 T helper cells, eosinophils, and inflammatory cytokines, such as interleukin (IL)-4, IL-5 and IL-13. Among patients with BP, the levels of immunoglobulin E and eosinophils are significantly increased in the peripheral blood and skin lesions, suggesting that the pathogenesis is tightly related to type 2 inflammation. To date, various targeted drugs have been developed to treat type 2 inflammatory diseases. In this review, we summarize the general process of type 2 inflammation, its role in the pathogenesis of BP and potential therapeutic targets and medications related to type 2 inflammation. The content of this review may contribute to the development of more effective drugs with fewer side effects for the treatment of BP.

Pilot study investigating BP-180 in extracellular vesicles derived from blister fluid of bullous pemphigoid patients

Bullous pemphigoid (BP) is an autoimmune blistering disease that targets the haemidesmosomal proteins, mainly BP180. Extracellular vesicles (EVs) have been demonstrated to carry tissue-specific autoantigens in the setting of autoimmune diseases and transplant organ rejection; this phenomenon was demonstrated to have pathogenic implications in autoimmune diseases and to correlate with transplant rejection severity. The purpose of this study was to identify the presence of BP targeted autoantigens in blister fluid derived EVs. We isolated, by size exclusion chromatography, EVs derived from blisters of BP-patients and from suction blisters of healthy donors. EV characterization was performed by flow cytometry and nanoparticle tracking analysis. Western blot analysis was used to investigate the presence of autoantigens. A suspension enriched in EVs was efficiently obtained from blister fluid from patients and healthy donors. EV-enriched fractions were enriched in particles with a size distribution characterizing small-EVs (main peak was present at 94.5 nm). BP180 was found, by western blot analysis, in EVs derived from blister fluid of 3 out 6 BP patients and in none of EVs isolated from suction blister fluid of healthy donors. BP230 and Dsg1 were not detectable in EVs of any of the samples. No specific clinical characteristics seemed to correlate to the presence of BP180 in EVs. The discovery of BP180 in EVs derived from blister fluid might help understanding BP pathogenesis.

What's new in the pathogeneses and triggering factors of bullous pemphigoid.

Bullous pemphigoid (BP) is a subepidermal blistering disease induced by autoantibodies to type XVII collagen (COL17, also called BP180) and BP230. Previous studies using patients' samples and animal disease models elucidated the complement-dependent and complement-independent pathways of blister formation, the pathogenic roles of immune cells (T and B cells, macrophages, mast cells, neutrophils, eosinophils), and the pathogenicity of IgE autoantibodies in BP. This review introduces the recent progress on the mechanism behind the epitope-spreading phenomenon in BP, which is considered to be important to understand the chronic and intractable disease course of BP, and the pathogenicity of anti-BP230 autoantibodies, mainly focusing on studies that used active disease models. To clarify the pathogenesis of BP, the mechanism behind the breakdown of immune tolerance to BP antigens should be investigated. Recent studies using various experimental models have revealed important roles for regulatory T cells in the maintenance of self-tolerance to COL17 and BP230 as well as in the suppression of inflammation triggered by the binding of antibodies to COL17. Notably, physical stresses such as trauma, thermal burns, bone fractures, irradiation and ultraviolet exposure, some pathologic conditions such as neurological diseases and hematological malignancies, and the use of dipeptidyl peptidase-IV inhibitors and immune checkpoint inhibitors have been reported as triggering factors for BP. These factors and certain underlying conditions such as genetic background, regulatory T-cell dysfunction or aging might synergistically affect some individuals and eventually induce BP. Further studies on the breakdown of self-tolerance and on the identification of key molecules that are relevant to blister formation and inflammation may expand our understanding of BP's etiology and may lead to the development of novel therapeutic approaches.

Differential expression of C5aR1 and C5aR2 in innate and adaptive immune cells located in early skin lesions of bullous pemphigoid patients.

Bullous pemphigoid (BP), the by far most frequent autoimmune subepidermal blistering disorder (AIBD), is characterized by the deposition of autoantibodies against BP180 (type XVII collagen; Col17) and BP230 as well as complement components at the dermal-epidermal junction (DEJ). The mechanisms of complement activation in BP patients, including the generation of C5a and regulation of its two cognate C5aRs, i.e., C5aR1 and C5aR2, are incompletely understood. In this study, transcriptome analysis of perilesional and non-lesional skin biopsies of BP patients compared to site-, age-, and sex-matched controls showed an upregulated expression of C5AR1, C5AR2, CR1, and C3AR1 and other complement-associated genes in perilesional BP skin. Of note, increased expressions of C5AR2 and C3AR1 were also observed in non-lesional BP skin. Subsequently, double immunofluorescence (IF) staining revealed T cells and macrophages as the dominant cellular sources of C5aR1 in early lesions of BP patients, while C5aR2 mainly expressed on mast cells and eosinophils. In addition, systemic levels of various complement factors and associated molecules were measured in BP patients and controls. Significantly higher plasma levels of C3a, CD55, and mannose-binding lectin-pathway activity were found in BP patients compared to controls. Finally, the functional relevance of C5aR1 and C5aR2 in BP was explored by two in vitro assays. Specific inhibition of C5aR1, resulted in significantly reduced migration of human neutrophils toward the chemoattractant C5a, whereas stimulation of C5aR2 showed no effect. In contrast, the selective targeting of C5aR1 and/or C5aR2 had no effect on the release of reactive oxygen species (ROS) from Col17-anti-Col17 IgG immune complex-stimulated human leukocytes. Collectively, this study delineates a complex landscape of activated complement receptors, complement factors, and related molecules in early BP skin lesions. Our results corroborate findings in mouse models of pemphigoid diseases that the C5a/C5aR1 axis is pivotal for attracting inflammatory cells to the skin and substantiate our understanding of the C5a/C5aR1 axis in human BP. The broad expression of C5aRs on multiple cell types critical for BP pathogenesis call for clinical studies targeting this axis in BP and other complement-mediated AIBDs.

Bullous Pemphygoid and Novel Therapeutic Approaches.

Bullous pemphigoid is a subepidermal blistering disease associated with autoantibodies (auto-ab) to BP180 and BP230 which affects elderly patients, predominately. Although it is a rare disease, bullous pemphigoid is the most common among the autoimmune bullous skin diseases. Systemic corticosteroids and immunosuppressants represent milestones in the treatment of patients suffering from bullous pemphigoid; however, therapeutic management of patients still represents a clinical challenge, owing to the chronic nature of the disease and to potential adverse effects related to the long-term use of systemic treatments. Recent discoveries on the pathogenesis of bullous pemphigoid have allowed investigation of new target therapies against selective pro-inflammatory mediators. These therapies appear to yield satisfactory results with fewer side effects in cases of refractory disease. The review discusses current evidence on these new therapeutic targets and specific drugs under investigation.

Interleukin-26-DNA complexes promote inflammation and dermal-epidermal separation in a modified human cryosection model of bullous pemphigoid.

Bullous pemphigoid (BP) is an autoimmune disease characterized by autoantibody-mediated activation of immune cells and subepidermal blister formation. Excess amounts of extracellular DNA are produced in BP, however, it remains unclear how extracellular DNA contributes to BP pathogenesis. Here we show a possible mechanism by which interleukin (IL)-26 binds to extracellular DNA released from neutrophils and eosinophils to support DNA sensing. Patients with BP exhibited high circulating levels of IL-26, forming IL-26–DNA complexes in the upper dermis and inside the blisters. IL-26–DNA complexes played a dual role in regulating local immunity and blister formation. First, they enhanced the production of inflammatory cytokines in monocytes and neutrophils. Second, and importantly, the complexes augmented the production and activity of proteases from co-cultured monocytes and neutrophils, which induced BP180 cleavage in keratinocytes and dermal-epidermal separation in a modified human cryosection model. Collectively, we propose a model in which IL-26 and extracellular DNA synergistically act on immune cells to enhance autoantibody-driven local immune responses and protease-mediated fragility of dermal-epidermal junction in BP.

A Comparison for Type 2 Cytokines and Lesional Inflammatory Infiltrations in Bullous Pemphigoid and Atopic Dermatitis.

Bullous pemphigoid (BP) and atopic dermatitis (AD) are both type 2 inflammatory skin diseases with similar clinical features. Thymic stromal lymphopoietin (TSLP) is an epithelial-derived cytokine which is upregulated in AD. However, the expression of TSLP in BP and the correlation between TSLP and inflammatory infiltrations have not been fully studied. To characterize the serum Th2 cytokines level and Th2 inflammatory cell infiltrations in BP and AD. To study TSLP levels in serum, blister fluids and expression in lesional skin in patients with BP and AD. TSLP level in serum and blister fluids was measured by enzyme-linked immunosorbent assay (ELISA). Inflammatory cells (CD4+ T cells, CD8+ T cells, CD1a+ cells, eosinophils and mast cells) were stained immunohistochemically and quantified by image analysis. TSLP level was significantly increased in blister fluids of BP and was highly expressed in lesional skin of BP and AD. Serum levels of IL-6, IL-4, IL-22, IFN-γ and thymic activation regulates chemokines (TARC) were significantly higher in patients with BP and AD than in healthy controls. CD4+ T cells, CD8+ T cells and CD1a+ cells were significantly more in upper dermis of BP and AD lesions. Eosinophils were found more in BP lesions while mast cells were found more in AD lesions than in healthy controls. A distinct correlation was found between TSLP levels and the intensities of CD4+ T cells, CD1a+ cells infiltrations. TSLP was significantly higher in blister fluids and skin lesions of BP, suggesting that it might contribute to the pathogenesis of BP. BP exhibited a similar type 2 immune response and a slight difference in cells infiltrations with AD.