Missing Insight Into T and B Cell Responses in Dermatitis Herpetiformis.

Dermatitis herpetiformis is a cutaneous form of celiac disease manifesting as an itching rash typically on the elbows, knees and buttocks. It is driven by the ingestion of gluten-containing cereals and characterized by granular deposits of immunoglobulin A in the papillary dermis. These antibodies target transglutaminase (TG) 3 and in the majority of patients they are also found in circulation. The circulating antibodies disappear and skin symptoms resolve as a result of gluten-free diet but the cutaneous anti-TG3 IgA deposits may persist for several years. In dermatitis herpetiformis, plasma cells secreting antibodies against TG3 are located in the intestinal mucosa similarly to those producing TG2 antibodies characteristic for celiac disease. In fact, both TG2- and TG3-specific plasma cells and gluten responsive T cells are found in dermatitis herpetiformis patients but the interplay between these cell populations is unknown. The small bowel mucosal damage in celiac disease is believed to be mediated by co-operation of cytotoxic intraepithelial T cells and the inflammatory milieu contributed by gluten-reactive CD4+ T cells, whereas the skin lesions in dermatitis herpetiformis appear to be devoid of gluten reactive T cells. Thus, how celiac disease-type intestinal T and B cell responses develop into an autoimmune condition affecting the skin is still incompletely understood. Finally, the skin and small bowel lesions may reappear upon reintroduction of gluten in patients treated with gluten-free diet but virtually nothing is known about the long-lived B cell and memory T cell populations activating in response to dietary gluten in dermatitis herpetiformis.

Mast cells and thymic stromal lymphopoietin (TSLP) expression positively correlates with pruritus intensity in dermatitis herpetiformis.

BACKGROUND: Pruritus is one of the leading symptoms of dermatitis herpetiformis (DH), however, studies on the pathogenesis of pruritus are scarce. Currently, skin mast cells (MCs) have been indicated to play a role in pruritus in autoimmune bullous disease. OBJECTIVE: To study the role of mast cells and related mediators involved in the pathogenesis of pruritus in DH. MATERIALS & METHODS: The number of MCs and expression of histamine and thymic stromal lymphopoietin (TSLP) was investigated in lesions of 29 DH cases and 15 healthy skin donors by immunohistochemistry. Fourteen patients were assessed for severity of pruritus based on the Numeric Rating Scale and Pruritus Grading System. The levels of histamine and TSLP in the serum of 18 DH patients and 15 healthy controls were also investigated. RESULTS: A significant increase in the number of MCs and degranulation was observed in DH lesions, which positively correlated with intensity of pruritus. In addition, skin TSLP but not histamine was shown to correlate with intensity of pruritus. No significant difference in expression of serum TSLP or histamine was observed between DH patients and healthy controls. CONCLUSION: These results suggest that skin MCs and TSLP might be involved in the pathogenesis of pruritus in DH which should be further clarified in future studies.

A Case of Dermatitis Herpetiformis With Fibrillar Immunoglobulin A Deposition: A Rare Pattern Not to Be Missed.

Dermatitis herpetiformis is a rare, chronic autoimmune disorder characterized by intense pruritic papules and vesicles, which can be associated with celiac disease and other autoimmune disorders. Its histologic characteristic is the accumulation of neutrophils within the papillary dermis with granular deposition of immunoglobulin A (IgA) observed under direct immunofluorescence. Herein, we report a 58-year-old woman who presented with a vesicular rash on the buttocks. The patient reported a recent history of genital herpes, Entamoeba histolytica colitis, recurrent hives, and eczema. A representative biopsy demonstrated features of spongiotic dermatitis and focal papillary dermal neutrophilic aggregates. Direct immunofluorescence revealed fibrillary IgA deposition in the papillary dermis, granular C3 deposition at the dermal-epidermal junction, and dermal papillae. The overall clinical, histologic, and DIF findings were consistent with those of dermatitis herpetiformis. The fibrillar IgA pattern is rare and easily overlooked by the unwary. Pathologists should be aware of this rare pattern, especially when the histologic findings are not classic.

Granzyme B is elevated in autoimmune blistering diseases and cleaves key anchoring proteins of the dermal-epidermal junction.

In healthy skin, epidermis and dermis are anchored together at the dermal-epidermal junction (DEJ), a specialized basement membrane pivotal for skin integrity and function. However, increased inflammation in the DEJ is associated with the disruption and separation of this junction and sub-epidermal blistering. Granzyme B (GzmB) is a serine protease secreted by immune cells. Dysregulated inflammation may lead to increased GzmB accumulation and proteolysis in the extracellular milieu. Although elevated GzmB is observed at the level of the DEJ in inflammatory and blistering skin conditions, the present study is the first to explore GzmB in the context of DEJ degradation in autoimmune sub-epidermal blistering. In the present study, GzmB induced separation of the DEJ in healthy human skin. Subsequently, α6/ß4 integrin, collagen VII, and collagen XVII were identified as extracellular substrates for GzmB through western blot, and specific cleavage sites were identified by mass spectrometry. In human bullous pemphigoid, dermatitis herpetiformis, and epidermolysis bullosa acquisita, GzmB was elevated at the DEJ when compared to healthy samples, while α6/ß4 integrin, collagen VII, and collagen XVII were reduced or absent in the area of blistering. In summary, our results suggest that regardless of the initial causation of sub-epidermal blistering, GzmB activity is a common final pathway that could be amenable to a single targeted treatment approach.

A retrospective study of dermatitis herpetiformis from an immunobullous disease clinic in north India.

BACKGROUND: Indian data on dermatitis herpetiformis (DH) is not available. The aim of this study was to investigate the demographic and clinicopathological characteristics of patients with DH and to study its association with other autoimmune diseases. METHODS: All data were collected from case record forms of patients registered in immunobullous disease clinic of our institute. The diagnosis was based on characteristic clinical and immuno/histopathological features. RESULTS: A total of 65 patients were included, which constituted 9.47% of the registered patients in the immunobullous disease clinic over 3.5 years. The male to female ratio was 1.4 : 1; the average age was 44.35 ± 15.52 years. Direct immunofluorescence showed granular IgA deposits at the papillary tips in 83.07% and basement membrane zone in 12.3% patients. Sixteen (24.1%) patients had associated celiac disease, and 15 (23.07%) patients had other autoimmune comorbidities such as hypothyroidism. Forty percent of patients on strict gluten-free diet achieved remission in 2 years, while 35.4% had frequent relapses as they continued gluten intake. CONCLUSIONS: Dermatitis herpetiformis is not a rare disease in northern India as previously believed. The clinical, histological, and immunopathological characteristics of Indian DH patients are similar to those reported in Caucasian populations. The limitations of our study include an absence of genetic testing for HLA-DQ2 or DQ8, nonavailability of kits for detecting IgA specific for epidermal transglutaminase (IgA eTG), and short follow-up period.

Expression of Elafin in Dermatitis Herpetiformis.

BACKGROUND: Elafin is a serine protease inhibitor that has various epithelial cell regulatory and immunomodulatory effects including inactivation of neutrophil elastases. This later role originated the interest of elafin in certain neutrophil-rich dermatoses. Interestingly, it has been speculated that elafin has a protective role by slowing the deamidation process of gliadin in celiac disease (CD), despite the typical absence of neutrophils in intestinal histologic samplings. Dermatitis herpetiformis (DH) is a chronic recurrent vesicular dermatitis associated with gluten hypersensitivity and also characterized by a neutrophilic infiltrate and granular immunoglobulin A deposits in papillary dermis. MATERIALS AND METHODS: We selected 31 formalin-fixed paraffin-embedded skin specimens of DH that demonstrated typical immunopathologic findings and probed them with rabbit polyclonal immunoglobulinG antielafin antibodies through standard immunohistochemistry analysis. Negative controls consisted of normal skin from elbow and knee surgical re-excisions specimen lacking residual tumor. Positive controls included skin biopsies of active plaque psoriasis, Sweet syndrome, and pyoderma gangrenosum. RESULTS: Similar to what has been previously reported in intestinal sampling of patients with active CD, abnormal expression of elafin was noted in virtually all probed skin biopsies of DH patients with active cutaneous disease. CONCLUSION: Under normal circumstances, keratinocytes overexpress elafin to downregulate a neutrophil mediated inflammatory response. The deficient expression of elafin in the aforementioned probed DH specimens correlates with previous similar elafin underexpression in intestinal samples of active CD. These histological findings suggest that these 2 gluten mediated disorders carry an abnormal elafin underexpression during disease activity.

Expression of the JAK/STAT Signaling Pathway in Bullous Pemphigoid and Dermatitis Herpetiformis.

A family of eleven proteins comprises the Janus kinases (JAK) and signal transducers and activators of transcription (STAT) signaling pathway, which enables transduction of signal from cytokine receptor to the nucleus and activation of transcription of target genes. Irregular functioning of the cascade may contribute to pathogenesis of autoimmune diseases; however, there are no reports concerning autoimmune bullous diseases yet to be published. The aim of this study was to evaluate the expression of proteins constituting the JAK/STAT signaling pathway in skin lesions and perilesional area in dermatitis herpetiformis (DH) and bullous pemphigoid (BP), as well as in the control group. Skin biopsies were collected from 21 DH patients, from 20 BP patients, and from 10 healthy volunteers. The localization and expression of selected STAT and JAK proteins were examined by immunohistochemistry and immunoblotting. We found significantly higher expression of JAK/STAT proteins in skin lesions in patients with BP and DH, in comparison to perilesional skin and the control group, which may be related to proinflammatory cytokine network and induction of inflammatory infiltrate in tissues. Our findings suggest that differences in the JAK and STAT expression may be related to distinct cytokines activating them and mediating neutrophilic and/or eosinophilic infiltrate.

Correlation between IL36α and IL17 and Activity of the Disease in Selected Autoimmune Blistering Diseases.

Dermatitis herpetiformis (DH), bullous pemphigoid (BP), and pemphigus vulgaris (PV) are autoimmune bullous skin conditions with eosinophilic and neutrophilic infiltrations. While cytokines are crucial for the affinity and activation of different leukocyte cells in the inflammation and blister formation, there are no studies concerning a role of IL-36. The goal of the study was to analyze whether interleukin 36 is involved in pathogenesis of DH, BP, and PV. And the second aim of the study was the estimation of correlation between Il-36 and IL-17 and titers of specific antibodies in these diseases. Expression of IL-36 and IL-17 was detected in serum in all DH, BP, and PV samples. Serum levels of IL-36 and IL-17α were statistically higher in DH, BP, and PV groups as compared to the control group. IL-36α levels were statistically higher in DH patients, as compared to patients with PV and BP. Our results showed that IL-36 may be helpful in the diagnostic and monitoring of the activity of the disease. IL 36 may play a relevant role of enrolling eosinophils and neutrophils in DH, BP, and PV and finally provoke tissue injury.

Extraintestinal manifestations of celiac disease: 33-mer gliadin binding to glutamate receptor GRINA as a new explanation.

We propose a biochemical mechanism for celiac disease and non-celiac gluten sensitivity that may rationalize many of the extradigestive disorders not explained by the current immunogenetic model. Our hypothesis is based on the homology between the 33-mer gliadin peptide and a component of the NMDA glutamate receptor ion channel - the human GRINA protein - using BLASTP software. Based on this homology the 33-mer may act as a natural antagonist interfering with the normal interactions of GRINA and its partners. The theory is supported by numerous independent data from the literature, and provides a mechanistic link with otherwise unrelated disorders, such as cleft lip and palate, thyroid dysfunction, restless legs syndrome, depression, ataxia, hearing loss, fibromyalgia, dermatitis herpetiformis, schizophrenia, toxoplasmosis, anemia, osteopenia, Fabry disease, Barret's adenocarcinoma, neuroblastoma, urinary incontinence, recurrent miscarriage, cardiac anomalies, reduced risk of breast cancer, stiff person syndrome, etc. The hypothesis also anticipates better animal models, and has the potential to open new avenues of research.

Granular C3 Dermatosis.

There has been no previous systematic study of bullous skin diseases with granular basement membrane zone deposition exclusively of C3. In this study we collected 20 such patients, none of whom showed cutaneous vasculitis histopathologically. Oral dapsone and topical steroids were effective. Various serological tests detected no autoantibodies or autoantigens. Direct immunofluorescence for various complement components revealed deposition only of C3 and C5-C9, indicating that no known complement pathways were involved. Studies of in situ hybridization and micro-dissection with quantitative RT-PCR revealed a slight reduction in expression of C3 in patient epidermis. These patients may represent a new disease entity, for which we propose the term "granular C3 dermatosis". The mechanism for granular C3 deposition in these patients is unknown, but it is possible that the condition is caused by autoantibodies to skin or aberrant C3 expression in epidermal keratinocytes.

[Expression of transient receptor potential lvanilloidreceptor 4 protein in autoimmune bullous skin disorders].

OBJEVTIVE: To investigate the expression of transient receptor potential lvanilloidreceptor 4 (TRPV4) protein in pemphigus vulgaris (PV), bullous pemphigoid (BP), dermatitis herpetiformis (DH), and epidermolysis bullosa acquisita (EBA), and explore the role of TRPV4 in the pathogenesis of these diseases. METHODS: TRPV4 protein in normal skin tissues and lesions of PV, BP, DH, and EBA were detected with immunohistochemistry. RESULTS: The positivity rate of TRPV4 protein expression was 61.90% in PV, 81.81% in BP, 72.22% in DH, and 68.42% in EBA. TRPV4-positive rates in these lesions were significantly lower than the rate in normal skin tissues (93.33%) and also differed significantly among these lesions (PV

Regulatory T cells as well as IL-10 are reduced in the skin of patients with dermatitis herpetiformis.

BACKGROUND: Dermatitis herpetiformis (DH) and celiac disease (CD) are considered as autoimmune diseases that share a defined trigger (gluten) and a common genetic background (HLA-DQ2/DQ8). However, the pathogenesis of DH is not fully understood and no data are available about the immune regulation in such a disease. OBJECTIVE: The aim of this study was to assess if alterations in the pattern of the immune response and, in particular, impairments of regulatory T (Tregs) cells may contribute to the phenotypic differences between DH and CD. METHODS: We investigated the presence of Tregs cell markers, in the skin, the duodenum and the blood of patients with DH by immunohistochemistry, confocal microscopy and flow cytometry. As controls, we included patients with bullous pemphigoid, patients with CD without skin lesions, as well as healthy subjects (HS). RESULTS: In the skin of DH patient, we found a significantly lower proportion of FOXP3(+) Tregs and IL-10(+) cells than in HS (p < 0.001 for both cell populations). In duodenal samples, no differences where found in the proportion of Tregs between patients with DH and patients with CD without skin manifestations. Finally, the frequency of CD25(bright)FOXP3(+) cells within the CD4(+) subset was significantly reduced in CD patients either with or without DH with respect to HS (p = 0.029 and p = 0.017, respectively). CONCLUSIONS: Our findings suggested that a reduction of Tregs may play a major role in the skin, leading to a defective suppressive function and thus to the development of the lesions. By contrast, no differences could be detected about Tregs between patients with DH and patients with CD in the duodenum, suggesting that the mechanisms of the intestinal damage are similar in both diseases.

IL-17 expression in dermatitis herpetiformis and bullous pemphigoid.

Dermatitis herpetiformis (DH) and bullous pemphigoid (BP) are skin diseases associated with eosinophilic and neutrophilic infiltrations. Although cytokines are critical for the inflammatory process, there are single findings concerning concentration of IL-17 in bullous diseases. The goal of this study was to assess IL-17 expression in DH and BP patients. Skin biopsies were taken from 10 DH, 14 BP patients and from 10 healthy subjects. The localization and expression of IL-17 was studied by immunohistochemistry and the serum concentration was measured by immunoassays. Expression of IL-17 in the epidermis and in influxed cells in dermis was detected in skin biopsies. Expression of IL-17 was statistically higher in epidermis and infiltration cells in specimens from BP than from DH patients. Examined interleukin expression was detected in perilesional skin of all patients but it was much lower than in lesional skin. The expression of IL-17 was not observed in biopsies from healthy people. Serum level of IL-17 was statistically higher in BP and DH groups as compared to control group. Our results provide the evidence that IL-17 may play an essential role in activating and recruiting eosinophils and neutrophils, which ultimately contribute to the tissue damage in DH and BP.

Flow cytometric analyses of circulating regulatory T cells in patients with dermatitis herpetiformis and other immune mediated dermatoses.

Regulatory T cells (Tregs) play a crucial role by maintaining the peripheral tolerance and inhibiting autoimmunity. In recent years, numerous autoimmune and immune-mediated diseases have been shown to present significant number depletion and/or function impairment of this subset. In the present study, we present a brief overview of the results obtained by our group in association with the centers belonging to the Italian Immunopathology Group, as to the expression levels and biological significance of circulating regulatory CD4+CD25+brightFOXP3+ T cells in a variety of immune-mediated skin diseases (such as psoriasis, scleroderma, bullous pemphigoid and GvHD), together with preliminary results achieved in patients with inflammatory bowel disease-related dermatoses. This review shows that this series of different cutaneous diseases characterised by an immune-mediated pathogenesis, share a significant down-regulation of circulating FOXP3+ Treg cells, whilst the treatment and the achievement of clinical response are generally associated with an opposite phenomenon with up-regulation of Treg cells. Future studies are mandatory to identify the effective role of these modifications in the disease pathogenesis as well as its relationship with the clinical response.

The expression of selected proapoptotic molecules in dermatitis herpetiformis.

The role of the process of apoptosis is investigated in the pathogenesis of many autoimmune diseases; however at present, there is not much information about its role in dermatitis herpetiformis. Skin biopsies were taken from 18 DH patients and from 10 healthy subjects. The localization and expression of Bax, Fas, FasL, TRAIL, TRAIL-R in skin lesions, and perilesional skin were studied by immunohistochemistry. Expression of Bax, Fas, and Fas ligand was detected in the keratinocytes in skin biopsies from DH patients. Expression of TRAIL and TRAIL receptor was confirmed in epidermis, infiltration cells, and some fibroblasts. The expression of examined molecules in biopsies from healthy people was observed only in single cells. There were statistically significant differences between lesional, perilesional, and healthy skin of control group in Bax expression analysis and between lesional skin and control group in Fas, FasL, and TRAIL expression. There were statistically significant differences between control group and perilesional skin in Bax and FasL expression. Our results show that selected proapoptotic molecules may take part in pathogenesis of dermatitis herpetiformis, but the role of apoptosis in this process is not clear.