Julie Plée

Innate immune cell-produced IL-17 sustains inflammation in bullous pemphigoid

Bullous pemphigoid (BP) is an autoimmune skin disease characterized by the binding of autoantibodies to components of the hemidesmosome structure resulting in an inflammatory response and subepidermal blister formation. To investigate the role of immune orientation in the inflammatory processes associated to disease progression, blister fluid, serum and biopsy specimens were collected from thirty one consecutive BP patients. Blister fluids displayed high level of IL-6, IL-17, IL-22, IL-23, whereas TGF-β was increased in BP sera. However neither immunocytochemistry on a trans-differentiation model of IL-17-producing PBMCs nor immunohistochemistry on BP biopsy specimens could demonstrate the presence of Th17 lymphocytes. Instead innate immune cells, especially neutrophils, produced IL-17 at the skin lesional site. Of note, superpotent topical corticosteroid application quickly and dramatically reduced both IL-17 expression and clinical signs of BP. Consistently, IL-17 upregulated MMP-9 and neutrophil elastase expression, two proteases involved in blister formation, thereof further demonstrating its role in the progress of BP. Finally IL-17-induced matrix degradation originated from neutrophil activation, initiated the formation of an amplification loop of the inflammatory response that could represent the underlying phenomenon leading to the maintenance and even disease extent. Thus, our results could open new therapeutic strategies for BP patients.

Integrating longitudinal serum IL-17 and IL-23 follow-up, along with autoantibodies variation, contributes to predict bullous pemphigoid outcome

Bullous pemphigoid (BP) is an inflammatory autoimmune bullous disease involving cytokines and proteases in the process of blister formation. Recently, IL-17 and IL-23 were evidenced in lesional skin and serum of BP patients at time of diagnosis, but their involvement in disease outcome has still not been investigated yet. We then analysed IL-17 and IL-23 serum levels during the first months of follow-up upon treatment. Compared with age- and sex- matched controls, high levels of IL-23 were observed at baseline in BP patients serum (P < 0.01), while IL-17 levels was not. However, some BP patients expressed high IL-17 serum level, independently of disease severity. In these patients, those with ongoing remission reduced IL-17 concentration upon treatment (P < 0.001), whereas IL-17 level remained elevated in patients who relapsed. Meanwhile, IL-23 serum levels increased during the first month of treatment in BP patients who later relapsed (P < 0.01) and MMP-9 serum level was not controlled. Accordingly, we found that both IL-17 and IL-23 increased MMP-9 secretion from leukocytes in-vitro. Then, we showed that elevated IL-17/IL-23 serum concentrations helped to discriminate BP patients who later relapsed. Such uncontrolled inflammatory response raises the question whether these molecules could become biological target for BP patients resistant to steroid treatment.

Bullous pemphigoid outcome is associated with CXCL10-induced matrix metalloproteinase 9 secretion from monocytes and neutrophils but not lymphocytes

Background: The outcome of bullous pemphigoid (BP), the most frequent autoimmune skin‐blistering disease, involves matrix metalloproteinase 9 (MMP‐9), IL‐17, and IL‐23 release from infiltrated inflammatory cells. The chemokine CXCL10 has been associated with several autoimmune diseases, but its participation in BP pathophysiology still needs to be clarified. Objective: We sought to assess whether BP outcome was associated with different CXCL10 levels and to evaluate the contribution of CXCL10 to the described cytokine/protease inflammatory loop associated with disease outcome. Methods: Skin biopsy specimens (n = 16), serum (n = 114), blister fluid (n = 23), and primary inflammatory cells from patients with BP were used to investigate CXCL10 expression and function. Results: At baseline, both resident cells, such as keratinocytes and fibroblasts, and infiltrating immune cells expressed CXCL10 at lesional sites in skin of patients with BP. CXCL10 levels were higher in blister fluid (P < .0001) and serum (P < .005) from patients with BP than in serum from age‐ and sex‐matched control subjects (n = 34). Furthermore, CXCL10 serum levels increased at day 60 only in patients who relapsed within the first year of treatment (n = 33, P < .005). Interestingly, CXCL10 expression could be upregulated by itself and IL‐17 in inflammatory cells. Notably, neutrophils and monocytes from patients with BP, but not lymphocytes, responded to CXCL10 by increasing MMP‐9 secretion through the activation of extracellular signal‐regulated kinase 1/2, p38, phosphoinositide‐3 kinase signaling pathways. Finally, CXCL10‐increased MMP‐9 secretion was inhibited by methylprednisolone and also by compound A, a novel nonsteroidal glucocorticoid receptor ligand. Conclusion: We showed that increased levels of inflammatory biomarkers in patients with BP, such as CXCL10, favor neutrophil‐ and monocyte‐associated MMP‐9 release and disease relapse and opened new therapeutic horizons in patients with this autoimmune disease.

Assessment of bullous pemphigoid disease area index during treatment: a prospective study of 30 patients.

Background: Recently, a consensus Bullous Pemphigoid Disease Area Index (BPDAI) was proposed to measure therapeutic outcomes in bullous pemphigoid (BP). Objective: To compare BPDAI with other clinical parameters of disease activity at baseline and to describe the variations of BPDAI during the initial phase of treatment. Methods: Thirty BP patients were included and followed for 1 year. BPDAI was assessed at baseline and on days 30, 90 and 360 by the same investigator. Concomitantly, the number of daily new blisters, the skin surface area of erythematous/eczematous/urticarial plaques and blisters/erosions, total lesion area (TLA), pruritus score and mucosal involvement were recorded. Results: At baseline, BPDAI was 46.7 ± 25 (mean ± SD); it was well correlated with erythematous/eczematous/urticarial skin surface (r = 0.63), TLA (r = 0.83), number of daily new blisters (r = 0.7; p ≤ 0.0002) and anti-BP180 autoantibodies (r = 0.49; p = 0.006), but not with anti-BP230 autoantibodies. For the 8 patients with severe BP at baseline, the mean BPDAI was 76.5, versus 35.9 for moderate BP (p = 0.0007). A value of 56 was proposed as a cut-off value for severe BP. BPDAI decreased to 11.9 ± 8.7, 10.7 ± 12.7 and 2.5 ± 4.1 on days 30, 90 and 360, respectively. Conclusion: BPDAI rapidly decreased during the early treatment stage of BP with variations almost totally conditioned by the skin activity component.

Positive Direct Immunofluorescence Is of Better Value than ELISA-BP180 and ELISA-BP230 Values for the Prediction of Relapse after Treatment Cessation in Bullous Pemphigoid: A Retrospective Study of 97 Patients

Background: ELISA-BP180 values and direct immunofluorescence (DIF) are prognostic factors for relapse after treatment cessation in bullous pemphigoid (BP). Objective: To determine the relevance of ELISA-BP230 antibodies for predicting relapse 6 months after treatment cessation. Methods: We retrospectively selected patients with BP and available data from ELISA-BP180 and -BP230 and DIF performed at treatment cessation. The rate of relapse was calculated at 6 months. We compared ELISA-BP180 and -BP230 values and DIF in patients with relapse and remission. Results: We included 97 patients. At 6 months, 25.6% of patients showed relapse. The proportion of patients with an ELISA-BP230 value ≥27 UA/ml was higher, but not significantly, for those with relapse than for those with remission (p = 0.11). The frequency of positive DIF findings was significantly higher for patients with relapse (p = 0.005). Conclusion: DIF is of better value than ELISA-BP180 and -230 tests to predict relapse after treatment cessation in BP.

Variation of the epidermal expression of glucocorticoid receptor‐beta as potential predictive marker of bullous pemphigoid outcome

Bullous pemphigoid (BP) is the most common autoimmune subepidermal blistering disease in Western countries. Although topical and/or systemic glucocorticoids treatment efficacy is widely recognized, up to 30% of patients with BP may undergo a relapse during the first year of treatment. We investigated the protein expression of the total glucocorticoid receptor and GRβ isoform in the skin biopsy specimens from patients with BP and wondered whether such investigation at baseline provided a tool to predict disease outcome. Total GR and GRβ protein expressions were detected by immunohistochemistry at baseline on 12 patients who later relapse and 11 patients who remained on remission in comparison with 14 control patients. The expression of GRβ in the epidermis of patients with BP who later relapse was significantly higher than that in the epidermis of patients with BP controlled upon corticosteroid treatment, which was also higher than control patients. Thus, our results suggest that increased protein expression of GRβ in skin epithelial cells is predictive of reduced steroid treatment efficacy, and therefore of increased risk of disease relapse in patients with BP.

Chapter 17 – Inflammation in Bullous Pemphigoid, a Skin Autoimmune Disease

Abstract Bullous pemphigoid (BP) is an example of an immunemediated disease associated with both a humoral and a cellular response directed against two well-characterized self-antigens, BP180 and BP230. Upon binding of autoantibodies to their target antigens, subepidermal blister formation results from a cascade of inflammatory events that involves complement activation, recruitment of inflammatory cells, and liberation of various cytokines, chemokines and proteases. The contribution of cytokines to the pathomechanisms of blistering is complex as they display pleiotropic activity on fibroblasts, keratinocytes, endothelial cells and innate infiltrating cells, which in turn may be crucial in modulating the adaptive autoimmune response, and subsequently affects disease severity and outcome thereof. In line with the cytokine production, BP has classically been characterized as a mix between Th1 and Th2 pattern with associated pathophysiological mechanisms already well investigated over the last decades, although not totally understood. In this chapter we tried to recapitulate our current knowledge of the contribution of cytokines in different steps of the pathophysiology mechanisms.

Anti-Type VII Collagen Antibodies Are Identified in a Subpopulation of Bullous Pemphigoid Patients With Relapse

Bullous pemphigoid (BP) is an autoimmune bullous skin disease characterized by anti-BP180 and anti-BP230 autoantibodies (AAbs). Mucous membrane involvement is an uncommon clinical feature of BP which may evoke epidermolysis bullosa acquisita, another skin autoimmune disease characterized by anti-type VII collagen AAbs. We therefore evaluated the presence of anti-type VII collagen AAbs in the serum of BP patients with and without mucosal lesions at time of diagnosis and under therapy. Anti-BP180, anti-BP230, and anti-type VII collagen AAbs were measured by ELISA in the serum of unselected patients fulfilling clinical and histo/immunopathological BP criteria at baseline (n = 71) and at time of relapse (n = 24). At baseline, anti-type VII collagen AAbs were detected in 2 out of 24 patients with BP presenting with mucosal involvement, but not in patients without mucosal lesions (n = 47). At the time of relapse, 10 out of 24 BP patients either displayed a significant induction or increase of concentrations of anti-type VII collagen AAbs (P < 0.01), independently of mucosal involvement. Those 10 relapsing BP patients were also characterized by a sustained high concentration of anti-BP180 AAb, whereas the serum anti-BP230 AAb concentrations did not vary in BP patients with relapse according to the presence of anti-type VII collagen AAbs. Thus, our study showed that anti-type VII collagen along with anti-BP180 AAbs detection stratified BP patients at time of relapse, illustrating a still dysregulated immune response that could reflect a potential epitope spreading mechanism in those BP patients.