Epidermal expression of eotaxins and thymic stromal lymphopoietin in eosinophil rich dermatoses

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.

Pruritogens in pemphigoid diseases: Possible therapeutic targets for a burdensome symptom

Pruritus is a hallmark feature in pemphigoid diseases, where it can be severe and greatly impact the quality of life of affected patients. Despite being a key symptom, the exact pathophysiological mechanisms involved in pruritus in pemphigoid are yet to be fully elucidated and effective therapies addressing them are limited. This review summarizes the present understanding of pruritus specific to pemphigoid diseases, especially the pruritogens that induce it, and the therapeutic options that have been explored so far. The majority of the available evidence is on bullous pemphigoid and epidermolysis bullosa acquisita. Histamine derived from basophils correlates with pruritus severity, with omalizumab demonstrating promising efficacy in pruritus for bullous pemphigoid. IL-4/-13 contribute to itch in bullous pemphigoid with dupilumab being evaluated in clinical trials. Other pruritogens of interest include substance P, tryptase, and thymic stromal lymphopoetin, with therapies targeting them requiring further investigation. Scratching behaviors contribute directly to blister formation through various mechanisms, such as pathological autoantibody recruitment, T helper cell type 1 polarization, and exposure of intracellular autoantigens. Treatments addressing these pathways may contribute to decreasing disease severity. Additional studies are needed to fully characterize how pruritus is regulated in pemphigoid diseases, to help pave the way to develop novel and effective therapeutics that will not only address pruritic symptoms but also decrease disease severity.

Expression of Thymic Stromal Lymphopoietin in Immune-Related Dermatoses

Thymic stromal lymphopoietin (TSLP), long known to be involved in Th2 response, is also implicated in multiple inflammatory dermatoses and cancers. The purpose of this study was to improve our understanding of the expression of TSLP in the skin of those dermatoses. Lesional specimens of representative immune-related dermatoses, including lichen planus (LP), discoid lupus erythematosus (DLE), eczema, bullous pemphigoid (BP), psoriasis vulgaris (PsV), sarcoidosis, and mycosis fungoides (MF), were retrospectively collected and analyzed by immunohistochemistry. Morphologically, TSLP was extensively expressed in the epidermis of each dermatosis, but the expression was weak in specimens of DLE. In a semiquantitative analysis, TSLP was significantly expressed in the epidermis in LP, BP, eczema, PsV, sarcoidosis, and MF. TSLP expression was higher in the stratum spinosum in LP, eczema, BP, PsV, and MF and higher in the stratum basale in sarcoidosis and PsV. Moreover, we found positive TSLP staining in the dermal infiltrating inflammatory cells of BP, PsV, and sarcoidosis. Our observation of TSLP in different inflammatory dermatoses might provide a novel understanding of TSLP in the mechanism of diseases with distinctly different immune response patterns and suggest a potential novel therapeutic target of those diseases.

Increased serum CCL26 level is a potential biomarker for the effectiveness of anti-PD1 antibodies in patients with advanced melanoma

Nivolumab plus ipilimumab combined therapy is among the most effective therapies for advanced melanoma. However, this therapy is also associated with a high frequency of immune-related adverse events (irAEs). To avoid such severe irAEs caused by additional administration of anti-CTLA4 antibodies, biomarkers to distinguish responders from non-responders among patients treated with anti-PD1 antibodies are important. The purpose of this study is to evaluate the increased serum levels of CCL11, CCL24, and CCL26 as a predictive biomarker for the efficacy of anti-PD1 antibodies in advanced cutaneous melanoma patients. This study analyzed increased serum levels of CCL11, CCL24, and CCL26 in 46 cases of advanced cutaneous melanoma treated with anti-PD1 antibodies. Serum levels on day 42 were compared to baseline (day 0) and analyzed statistically. Receiver operating characteristic curves were established to evaluate the correlation between serum levels of CCL11, CCL24, and CCL26 and efficacy of anti-PD1 antibodies. Increased serum levels of CCL26 correlated significantly with the efficacy of anti-PD1 antibodies. In contrast, no significant correlations were seen between increased serum levels of CCL11 and CCL24 and efficacy of anti-PD1 antibodies. Increased serum levels of CCL26 may be a useful biomarker for identifying those patients with advanced cutaneous melanoma most likely to benefit from anti-melanoma immunotherapy.

Overexpression of helper T cell type 2-related molecules in the skin of patients with eosinophilic dermatosis of hematologic malignancy

BACKGROUND

Eosinophilic dermatosis of hematologic malignancy (EDHM) is a rare dermatosis associated with blood tumors.

OBJECTIVE

To characterize the expression of T-cell and B-cell markers and pruritogenic mediators in EDHM skin.

METHODS

Immunohistochemical and immunofluorescence analysis were performed in 12 skin samples of EDHM, 11 samples of bullous pemphigoid (BP), and 5 samples from healthy controls (HC). Serum levels of interleukin (IL) 4 were analyzed in 11 patients with EDHM, 11 BP patients, and 5 HC by enzyme-linked immunosorbent assay.

RESULTS

T-cell markers, including clusters of differentiation (CD) 3, CD4, CD8, and CD5 were significantly overexpressed in EDHM and BP skin compared to HC. A predominance of CD4⁺ over CD8⁺ cells and GATA3⁺ (helper T cell type 2 [Th2] marker) over T-bet⁺ (Th1 marker) cells were observed. FOXP3 expression was increased but the FOXP3/CD4 ratio was low. B-cell markers were under-represented, without significant differences between the 3 groups. IL-4 and IL-31 were significantly overexpressed in EDHM and BP compared to HC and colocalized with the Th2-associated marker GATA3. Eotaxin-1 was significantly overexpressed in EDHM compared to BP and HC. IL-4 serum concentration was significantly increased in EDHM and BP compared to HC.

LIMITATIONS

Small sample size; retrospective design.

CONCLUSIONS

Targeting Th2-related molecules, in particular IL-4, holds promise for EDHM management.

Thymic Stromal Lymphopoietin in Cutaneous Immune-Mediated Diseases

Thymic stromal lymphopoietin (TSLP) was initially demonstrated to be critical in regulating inflammatory responses among various allergic disorders (such as atopic dermatitis, food allergy, and asthma). Although two isoforms (short form and long form) of TSLP have been demonstrated in human tissues, the long form of TSLP (lfTSLP) is strongly implicated in the pathogenesis of allergies and cutaneous immune-mediated diseases. The immunomodulatory activity of lfTSLP varies widely, driving T helper (Th) cells polarizing Th2 and Th17 immune responses and inducing itch. Moreover, lfTSLP is closely associated with skin fibrosis, epidermal hyperplasia, angiogenesis, and homeostatic tolerogenic regulations. This review highlights significant progress from experimental and clinical studies on lfTSLP in cutaneous immune-mediated diseases (atopic dermatitis, psoriasis, bullous pemphigoid, systemic sclerosis, chronic spontaneous urticaria, Behçet’s disease, vitiligo, rosacea, systemic lupus erythematosus, and alopecia areata). We also offer original insights into the pleiotropic properties of the cytokine TSLP in various pathophysiological conditions, with significant clinical implications of TSLP-targeted therapies for immune-mediated skin diseases in the future.

Immunoinflammatory Biomarkers in Serum Are Associated with Disease Severity in Atopic Dermatitis

BACKGROUND

A growing body of evidence links various biomarkers to atopic dermatitis (AD). Still, little is known about the association of specific biomarkers to disease characteristics and severity in AD.

OBJECTIVE

To explore the relationship between various immunological markers in the serum and disease severity in a hospital cohort of AD patients.

METHODS

Outpatients with AD referred to the Department of Dermatology, Bispebjerg Hospital, Copenhagen, Denmark, were divided into groups based on disease severity (SCORAD). Serum levels of a preselected panel of immunoinflammatory biomarkers were tested for association with disease characteristics. Two machine learning models were developed to predict SCORAD from the measured biomarkers.

RESULTS

A total of 160 patients with AD were included; 53 (33.1%) with mild, 73 (45.6%) with moderate, and 34 (21.3%) with severe disease. Mean age was 29.2 years (range 6-70 years) and 84 (52.5%) were females. Numerous biomarkers showed a statistically significant correlation with SCORAD, with the strongest correlations seen for CCL17/thymus and activation-regulated chemokine (chemokine ligand-17/TARC) and CCL27/cutaneous T cell-attracting-chemokine (CTACK; Spearman R of 0.50 and 0.43, respectively, p < 0.001). Extrinsic AD patients were more likely to have higher mean SCORAD (p < 0.001), CCL17 (p < 0.001), CCL26/eotaxin-3 (p < 0.001), and eosinophil count (p < 0.001) than intrinsic AD patients. Predictive models for SCORAD identified CCL17, CCL27, serum total IgE, IL-33, and IL-5 as the most important predictors for SCORAD, but with weaker associations than single cytokines.

CONCLUSIONS

Specific immunoinflammatory biomarkers in the serum, mainly of the Th2 pathway, are correlated with disease severity in patients with AD. Predictive models identified biomarkers associated with disease severity but this finding warrants further investigation.

Thymic Stromal Lymphopoietin Is Implicated in the Pathogenesis of Bullous Pemphigoid by Dendritic Cells

Objectives

Both thymic stromal lymphopoietin (TSLP) and dendritic cells (DCs) are involved in many autoimmune diseases, but the potential roles of TSLP and DCs in bullous pemphigoid (BP) have not been clarified. We sought to explore the contributions of TSLP and DCs in patients with BP.

Methods

TSLP levels in sera and blister fluids were measured by enzyme-linked immunosorbent assay. The TSLP expression in the BP lesional skin was detected by immunohistochemical staining. Infiltration of DCs, marked by DC-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN), and its relationship with TSLP and TSLP receptors was evaluated by immunofluorescence staining.

Results

We found that TSLP levels in sera and in blister fluids of patients with BP were higher compared to the control groups. In patients with BP, TSLP levels in sera correlated with TSLP levels in blisters. The expression of TSLP in the BP lesional skin was higher compared to the healthy controls' skin. Greater numbers of TSLP-positive cells were observed in the epidermis of patients with BP compared to the healthy controls. Greater numbers of DC-SIGN-positive cells were present in the BP lesional skin compared to the skin of controls. The expression of TSLP was highly upregulated in DC-SIGN-positive cells, and most DC-SIGN-positive cells expressed TSLP receptors.

Conclusions

We conclude that TSLP may activate DC-SIGN-positive DCs directly, which may be involved in the pathogenesis of BP.

Eosinophils in Bullous Pemphigoid

Bullous pemphigoid (BP) is an autoimmune blistering disorder with substantial morbidity and mortality. BP is regarded as a disorder driven by IgG due to BP180 and BP230 IgG autoantibodies, yet, new advances highlight the function of eosinophils and IgE autoantibodies in BP. Evidence supports that eosinophils are involved in BP pathogenesis, notably, these include the presence of IL-5, eotaxin, and eosinophil-colony stimulating factor in blister fluid, peripheral blood eosinophilia is present in nearly 50% of affected patients, eosinophils are found against the dermo-epidermal junction (DEJ) when BP serum is present, metalloprotease-9 is secreted by eosinophils at blister sites, blister fluid of BP patients contains eosinophil granule proteins which are located along the lamina lucida of the BMZ in patients with BP and correspond with disease clinically, eosinophil extracellular traps (EET) have been linked to DEJ splitting, IL-5 activated eosinophils cause DEJ separation when BP serum is present, and eosinophils are requisite to drive anti-BP180 IgE mediated blistering of the skin. Yet, the mechanism whereby eosinophils contribute to the pathogenesis of BP remains to be explored. In this review, we examine the role of eosinophils in BP while offering a basis to explain the pathomechanisms of eosinophils in BP.