The elastin peptide VGVAPG increases CD4+ T-cell IL-4 production in patients with chronic obstructive pulmonary disease.

BACKGROUND: In chronic obstructive pulmonary disease (COPD), lung-infiltrating inflammatory cells secrete proteases and participate in elastin breakdown and genesis of elastin-derived peptides (EP). In the present study, we hypothesized that the pattern of T lymphocytes cytokine expression may be modulated by EP in COPD patients. METHODS: CD4+ and CD8+ T-cells, sorted from peripheral blood mononuclear cells (PBMC) collected from COPD patients (n = 29) and controls (n = 13) were cultured with or without EP. Cytokine expression in T-cell phenotypes was analyzed by multicolor flow cytometry, whereas desmosine concentration, a specific marker of elastin degradation, was measured in sera. RESULTS: Compared with control, the percentage of IL-4 (Th2) producing CD4+ T-cells was decreased in COPD patients (35.3 ± 3.4% and 26.3 ± 2.4%, respectively, p < 0.05), whereas no significant differences were found with IFN-γ (Th1) and IL-17A (Th17). Among COPD patients, two subpopulations were observed based on the percentage of IL-4 (Th2) producing CD4+ T-cells, of which only one expressed high IL-4 levels in association with high levels of desmosine and strong smoking exposure (n = 7). Upon stimulation with VGVAPG, a bioactive EP motif, the percentage of CD4+ T cells expressing IL-4 significantly increased in COPD patients (p < 0.05), but not in controls. The VGVAPG-induced increase in IL-4 was inhibited in the presence of analogous peptide antagonizing VGVAPG/elastin receptor (S-gal) interactions. CONCLUSIONS: The present study demonstrates that the VGVAPG elastin peptide modulates CD4+ T-cells IL-4 production in COPD. Monitoring IL-4 in circulating CD4+ T-cells may help to better characterize COPD phenotypes and could open a new pharmacologic opportunity through CD4+ T-cells stimulation via the VGVAPG/S-gal receptor in order to favor an anti-inflammatory response in those COPD patients.

Matrix remodelling and MMP expression/activation are associated with hidradenitis suppurativa skin inflammation.

Hidradenitis suppurativa/acne inversa (HS) is a chronic, inflammatory, recurrent, debilitating skin disease of the hair follicle, associated with considerable tissue remodelling. Although abnormal cytokine expression was detected both in perilesional and in uninvolved skin, up to now there is no model allowing a better understanding of the implicit inflammatory mechanisms in HS. The aim of this study was to investigate the inflammatory response in HS skin by mean of an ex vivo model culture. To that purpose, nine skin biopsy specimens from patients suffering from HS and controls were cultured up to 4 days. Microscopy imaging investigations showed variations of collagen I and III organization, and an increase in elastin fibres fragmentation in HS skin after 4 days of culture. The HS matrix structure remodelling was associated with high level of MMP-2 and MMP-9 in HS lesional skin. After 4 days of culture, the MMP expression in HS perilesional skin reached the level observed in HS lesional skin. Concomitantly, an increase in IL-1ß concentration was observed in all skin samples after 4 days of culture, although IL-1ß concentrations remained significantly higher in HS lesional skin as compared with control skin. Meanwhile, neither IL-17 concentrations nor the inflammasome components NLRP3 and caspase-1 varied. Thus, our HS skin model culture showed that MMP-induced matrix alteration could participate in HS inflammation by releasing biological active peptides and inflammatory factors from the extracellular matrix (ECM), and open new opportunities to investigate the regulation of the inflammatory mechanism associated with HS.

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.

The Interleukin-17 Family of Cytokines in Breast Cancer.

Breast cancer (BC) is the most common cancer in women worldwide and remains a major cause of mortality with an expected 137,000 death this year in Europe. Standard management of metastatic BC comprises hormonotherapy, chemotherapy, and targeted therapies. Cyclin dependent kinase (CDK) and mammalian target of rapamycin (mTOR) inhibitors have recently proved their efficiency in hormonal receptor expressing BC. Checkpoint proteins inhibition is being evaluated in phase 3 studies. Since inflammation is constantly present in cancers, research teams have focused their attention on the interleukin-17 (IL-17) family of proinflammatory cytokines. Preclinical experiments have reported both pro and antitumor effects depending on the conditions. In the present article, we review the accumulating evidences about the roles of IL-17 in BC and discuss whether this family of cytokines could be a new target in anticancer treatments.

Biomarkers related to bullous pemphigoid activity and outcome.

Bullous pemphigoid (BP) is the most common autoimmune subepidermal blistering disease of the skin. Investigation of the BP-associated pathophysiological processes during the last decades showed that the generation of autoantibodies directed against the hemidesmosome proteins BP180 and BP230, a hallmark of the BP-associated autoimmune response, leads to the recruitment of inflammatory immune cells at the dermal-epidermal junction, and subsequently to the release of a large amount of inflammatory molecules involved in blister formation. Analysis in transversal and longitudinal studies of autoantibodies and inflammatory molecules production both at the time of diagnosis and under treatment was mainly performed within the serum but also in the blister fluid. Some autoimmune or inflammatory molecules expression was related to the presence of clinical signs, while others were mere bystanders. In this review, we focused on the autoimmune and inflammatory molecules that have been identified as potential biomarkers of BP development and outcome.

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 GRß 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 GRß 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 GRß 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 GRß in skin epithelial cells is predictive of reduced steroid treatment efficacy, and therefore of increased risk of disease relapse in patients with BP.

Targeting the Tumor Microenvironment: The Protumor Effects of IL-17 Related to Cancer Type.

The inflammatory process contributes to immune tolerance as well as to tumor progression and metastasis. By releasing extracellular signals, cancerous cells constantly shape their surrounding microenvironment through their interactions with infiltrating immune cells, stromal cells and components of extracellular matrix. Recently, the pro-inflammatory interleukin 17 (IL-17)-producing T helper lymphocytes, the Th17 cells, and the IL-17/IL-17 receptor (IL-17R) axis gained special attention. The IL-17 family comprises at least six members, IL-17A, IL-17B, IL-17C, IL-17D, IL-17E (also called IL-25), and IL-17F. Secreted as disulfide-linked homo- or heterodimers, the IL-17 bind to the IL-17R, a type I cell surface receptor, of which there are five variants, IL-17RA to IL-17RE. This review focuses on the current advances identifying the promoting role of IL-17 in carcinogenesis, tumor metastasis and resistance to chemotherapy of diverse solid cancers. While underscoring the IL-17/IL-17R axis as promising immunotherapeutic target in the context of cancer managing, this knowledge calls upon further in vitro and in vivo studies that would allow the development and implementation of novel strategies to combat tumors.

The DNA hypomethylating agent, 5-aza-2'-deoxycytidine, enhances tumor cell invasion through a transcription-dependent modulation of MMP-1 expression in human fibrosarcoma cells.

In diseases such as cancer, cells need to degrade the extracellular matrix (ECM) and therefore require high protease levels. Thus, aberrant tissue degradation is associated to matrix metalloproteinases (MMPs) overexpression resulting from different mechanisms including epigenetic events. One of the most characterized epigenetic mechanisms is DNA methylation causing changes in chromatin conformation, thereby decreasing the accessibility to the transcriptional machinery and resulting in a robust gene silencing. Modulation of DNA methylation by DNA hypomethylating agents such as 5-aza-2'-deoxycytidine (5-azadC) is widely used in epigenetic anticancer treatments. Here, we focus on the effects of this drug on the expression level of MMP-1, -2, and -9 in human HT1080 fibrosarcoma cells. We demonstrate that 5-azadC increases MMP expression at both mRNA and protein levels, and promotes invasion potential of HT1080 cells. Using broad-spectrum and specific MMP inhibitors, we establish that MMP-1, but not MMP-2 and -9, plays a key role in 5-azadC-enhanced cell invasion. We show that 5-azadC induces MMP-1 expression through a transcriptional mechanism without affecting MMP-1 promoter methylation status. Finally, we demonstrate that 5-azadC treatment increases the nuclear levels of Sp1 and Sp3 transcription factors, and modulates their recruitment to the MMP-1 promoter, resulting in chromatin remodeling associated to 5-azadC-induced MMP-1 expression. All together, our data indicate that the hypomethylating agent 5-azadC modulates, mainly via Sp1 recruitment, MMP-1 expression resulting in an increased invasive potential of HT1080 cells.

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.

Impairment of neutrophil reactivity to elastin peptides in COPD.

RATIONALE: Neutrophils play an important role in the inflammatory process associated with chronic obstructive pulmonary disease (COPD). Lung-infiltrating neutrophils secrete elastinolytic proteases that participate in elastin breakdown and the formation of elastin peptides (EPs). OBJECTIVES: We hypothesized that circulating neutrophil-associated immune response may be modulated by EPs during COPD. METHODS: Neutrophils obtained from patients with either stable or exacerbated COPD and controls were cultured with or without EPs. Cell chemotaxis was analysed by the Boyden method and cytokine expression was analysed by ELISA and real-time reverse transcriptase PCR. Bacterial phagocytosis and killing of ingested bacteria were evaluated after incubation with Pseudomonas aeruginosa. Reactive oxygen species (ROS) measurement and elastin receptor expression were determined by flow cytometry. RESULTS: Chemotactic activity of neutrophils from patients with COPD towards the VGVAPG EP was reduced compared with controls. VGVAPG increased proinflammatory cytokine synthesis and bacterial load, but reduced ROS production in neutrophils from controls and from patients with stable COPD. Patients with exacerbated COPD were unresponsive to VGVAPG treatment. These findings were associated with a decreased or almost complete loss of S-Gal elastin receptor expression in neutrophils from patients with stable or exacerbated COPD, respectively. CONCLUSIONS: The study demonstrates that the response of neutrophils from patients with COPD to VGVAPG varied according to COPD phase and critical level of S-Gal expression. S-Gal downregulation could result from a feedback mechanism induced by high levels of EPs.

Mechanical forces-induced human osteoblasts differentiation involves MMP-2/MMP-13/MT1-MMP proteolytic cascade.

Matrix metalloproteinase (MMP) family proteins play diverse roles in many aspects of cellular processes such as osteoblastic differentiation. Besides, mechanical forces that occur in 3D collagen gel promote the osteoblastic phenotype and accelerate matrix mineralization. Although MMPs have been involved in bone differentiation, the proteolytic cascades triggered by mechanical forces are still not well characterized. In this study, we have investigated the contribution of both proteolytic cascades, MMP-3/MMP-1 and MMP-2/MMP-13/MT1-MMP in the differentiation of human osteoblasts cultured in a floating type I collagen lattice (FL) versus an attached collagen lattice (AL). Compared to AL, contraction of human osteoblasts-populated FL led to a fast (1 day) induction of alkaline phosphatase (ALP), bone sialoprotein (BSP), osteoprotegerin (OPG), and Runx-2 expression. At day 4, osteocalcin (OC) overexpression preceded the formation of calcium-containing nodule formation as assessed by X-ray analyses. MMP-1 and MMP-3 were produced to similar extent by cells cultured in FL and AL, whereas contraction of collagen lattices triggered both mRNA overexpression of MMP-2, MMP-13, and MT1-MMP (i.e., MMP-14), and their activation as evidenced by Western blotting or zymographic analyses. Down-regulating MT1-MMP expression or activity either by siRNA transfection or supplementation of culture medium with TIMP-1 or TIMP-2 highlighted the contribution of that enzyme in OC, ALP, and OPG expression. MMP-2 and MMP-13 were more directly involved in BSP expression. So, these results suggest that the main proteolytic cascade, MMP-2/MMP-13/MT1-MMP, and more particularly, its initial regulator MT1-MMP is involved in osteoblast differentiation through mechanical forces.

Inhibition of stromelysin-1 by caffeic acid derivatives from a propolis sample from Algeria.

Stromelysin-1 (matrix metalloproteinase-3: MMP-3) occupies a central position in collagenolytic and elastolytic cascades, leading to cutaneous intrinsic and extrinsic aging. We screened extracts of a propolis sample from Algeria with the aim to isolate compounds able to selectively inhibit this enzyme. A butanolic extract (B (3)) of the investigated propolis sample was found to potently inhibit MMP-3 activity (IC (50) = 0.15 ± 0.03 µg/mL), with no or only weak activity on other MMPs. This fraction also inhibited plasmin amidolytic activity (IC (50) = 0.05 µg/mL) and impeded plasmin-mediated proMMP-3 activation. B (3) was fractionated by HPLC, and one compound, characterized by NMR and mass spectroscopy and not previously identified in propolis, i.e., (+)-chicoric acid, displayed potent IN VITRO MMP-3 inhibitory activity (IC (50) = 6.3 × 10 (-7) M). In addition, both caffeic acid and (+)-chicoric acid methyl ester present in fraction B (3) significantly inhibited UVA-mediated MMP-3 upregulation by fibroblasts.

Probing tumor and peritumoral tissues in superficial and nodular basal cell carcinoma using polarized Raman microspectroscopy.

Basal cell carcinoma (BCC) can sometimes lead, through a possible invasion of the dermis and the subcutaneous tissue, to serious local damage to the patient. Several histological types of BCC are reported, among them, the superficial, nodular and infiltrative forms. This study reports the use of polarized Raman microspectroscopy on the nodular and superficial types to discriminate between healthy epidermis and tumor, and between normal and peritumoral stroma. This technique probes additional information than conventional Raman spectroscopy because it is sensitive to the molecular ordering of tissue components. Depolarization ratios and hierarchical cluster analysis demonstrate that polarized Raman microspectroscopy can better identify the tumor and the peritumoral dermis than conventional Raman microspectroscopy, and hence gives potential complementary data about their molecular characteristics (molecular composition, secondary structure of proteins, intra- and/or inter-molecular bonding). Our findings also show that although superficial and nodular types of BCC were analysed, clear differences between the spectra of peritumoral and normal dermis could be detected.

Neutrophil Extracellular Traps Generation Relates with Early Stage and Vascular Complications in Systemic Sclerosis.

Systemic sclerosis (SSc) is a systemic disease characterized by a great clinical and immunological heterogeneity whose pathophysiology is still being unraveled. Recently, innate immunity has been proposed to participate to the pathogenesis of SSc. In this study, we investigated the release of neutrophil extracellular traps (NETs) according to patient phenotype. Polymorphonuclear neutrophils (PMN) from 34 SSc patients and 26 healthy controls were stimulated by serum from SSc or healthy subject. NETs were visualized using epifluorescence microscope after DNA, myeloperoxidase, and Histone H3 tagging. Area of NETs were quantified using an original macro running in ImageJ® software. PMN from SSc patients were significantly more prone to releasing NETs than control PMN after autologous stimulation. PMN from patients with severe vascular complications (pulmonary arterial hypertension, digital ulcers) produced more NETs than PMN from other SSc patients and their aberrant NET production appeared to be sustained over time. In patients with pulmonary interstitial disease or extensive cutaneous fibrosis, NET production was high at an early stage of the disease before progressively decreasing. Both serum factors and PMN activation status were involved in the enhanced production of NETs in SSc. Consequently, neutrophils and especially NETosis represent new physiopathological and therapeutic fields in SSc.

Ceramide inhibition of MMP-2 expression and human cancer bronchial cell invasiveness involve decreased histone acetylation.

Ceramides have been proposed as potential therapeutic strategy with regard to their ability to induce cell death. We previously demonstrated that C2-ceramide generated apoptosis in bronchocarcinoma BZR cells. We here investigated whether ceramides also target other molecules involved in cell-cell or cell-matrix interactions during cancer progression. A SuperArray(R) analysis showed that ceramides modulate gene expression after 2 h. Among deregulated genes, we observed an inhibition of the transcript coding for the pro-metastatic enzyme MMP-2. The pharmacological inhibitor of caspases cascade, ZVAD-fmk, did not prevent C2-ceramide-induced down-regulation of MMP-2 ruling out apoptosis as a mediator of this event, whereas inhibition of oxidative stress using NAC confirmed a role for ROS. This effect of C2-ceramide was associated with changes in histone H3 acetylation. However, although histone deacetylase inhibitors are also currently under investigation for their anti-tumor activity, we demonstrated here that a combined treatment with trichostatin A abrogated both MMP-2 down-regulation and reduced invasive properties elicited by C2-ceramide alone. Hence, this study demonstrates that besides its apoptotic effect, C2-ceramide also exhibits anti-invasive properties, showing a dual beneficial effect against cancer progression, but casts some doubt on the use of HDAC inhibitors as combined treatment with drugs that trigger the ceramide pathway.

Role of the elastin receptor complex (S-Gal/Cath-A/Neu-1) in skin repair and regeneration.

Impaired elastic fiber assembly constitutes one major problem in skin wound healing. Recent data indicate that a ternary complex involving a splicing form of beta-galactosidase associated with cathepsin-A and neuraminidase-1 directs the transport of tropoelastin to the fibroblast plasma membrane and participates in the deposition of the elastin precursor onto a microfibrillar scaffold. In addition, this elastin receptor complex is ubiquitously expressed and also acts as a true receptor for elastin-derived peptides produced during the initial stage of wound repair following elastase-mediated proteolysis action. Among the peptides generated, those having a x.G.x.x.P.G. motif upregulate (i) keratinocyte migration, (ii) endothelial cell angiogenic phenotype, (iii) fibroblast proliferation, and (iv) induction of the expression of matrix metalloproteinases, type I collagen, and tropoelastin. All of these properties could accelerate the different stages of wound repair. Elastin-derived peptides from a chemical or a proteolytic digest of insoluble elastin alone or linked to the collagen scaffold significantly improve skin wound healing and dermal regeneration in vivo in several animal models. Such a beneficial influence has been recently extended to the treatment of burn patients. In this respect, recent investigations have focused on the design of elastin-derived peptides or elastin-building blocks, as obtained from peptide chemistry or by genetic engineering, to elaborate biocompatible elastin peptides, which are considered as ideal biomaterials for "catalyzing" skin repair and regeneration following injury.

Association of Transient Palmoplantar Keratoderma With Clinical and Immunologic Characteristics of Bullous Pemphigoid.

Importance: Development of transient palmoplantar keratoderma (PPK) with bullous pemphigoid (BP) has only been described in 2 isolated case reports. The clinical significance and the pathophysiologic mechanisms of this association are unknown. Objective: To examine the clinical characteristics and immunological profile of patients with BP who develop transient PPK and analyze therapeutic options and outcomes. Design, Setting, and Participants: In this case series, patients with BP who developed acquired, transient PPK, and were treated at a single institution from January 1, 2015, through December 31, 2017, were studied. Main Outcomes and Measures: Clinical and immunological activity of BP, treatment administrated before and after PPK appearance, and patient outcomes. Results: Six patients with BP and transient PPK were identified and included in the study. There were 5 women and 1 man with a mean age of 72 years. At baseline, all patients had a generalized, multibullous BP and high serum anti-BP180 antibodies (mean, 130 U/mL; range, 73-150), whereas anti-BP230 antibodies were elevated in only 1 case. The PPK appeared a mean 6.2 (range, 2-12) months after BP diagnosis, following a prolonged period of disease activity with recurrent flares. When the PPK occurred, BP was uncontrolled on therapy (mean Bullous Pemphigoid Disease Activity Index [BPDAI] score, 57; range, 34-105; mean anti-BP180 antibodies titer, 122 U/mL; range, 81-150). On administration of additional systemic immunosuppressive therapies, the PPK healed progressively in a mean 4.3 months (range, 2-9), along with BP clinical remission in 4 of 6 patients. No relationship was found between PPK occurrence and anti-BP180/230 antibodies profiles. In contrast, blister fluids collected at the time of PPK displayed a much higher level of interleukin 1ß (IL-1ß) compared with those collected in the absence of PKK. Expression of IL-17A, IL-17F, and IL-22 was also enhanced in the blister fluid of patients with BP who had PPK. Conclusions and Relevance: To our knowledge, this is the first report of 6 cases of BP with transient PPK with extensive immunological investigation. The PPK appeared after a prolonged period of clinical BP activity punctuated with recurrent relapses, was transient, and healed after BP control with additional immunosuppressive therapy. Enhanced expression of a particular cytokine panel in the blister fluid at time of PPK could support keratinocyte proliferation as described in patients with psoriasis. Transient PPK could represent a clinical marker of severe, treatment-resistant BP.

IL-23/IL-17 Axis Activates IL-1ß-Associated Inflammasome in Macrophages and Generates an Auto-Inflammatory Response in a Subgroup of Patients With Bullous Pemphigoid.

Bullous Pemphigoid (BP) is a skin autoimmune blistering disease characterized by immune-mediated degradation of the dermo-epidermal junction and release of a large number of inflammatory cytokines. Interleukin-1ß (IL-1ß) is a pleiotropic pro-inflammatory cytokine associated with inflammasome activation and known to be pivotal in several auto-immune and auto-inflammatory diseases. We sought to clarify the presence of inflammasome-dependent IL-1ß and to investigate its role in BP. Skin biopsy specimens (n = 13), serum (n = 60), blister fluid (n = 26), and primary inflammatory cells from patients with BP were used to investigate inflammasome activation and function. We here highlighted a differential occurrence of a functional in situ inflammasome in patients with BP, biologically distinguished by IL-1ß and NLRP3 expression. Clinically, elevated IL-1ß levels were associated with the presence of erythema and urticarial plaques reflecting the inflammatory phase preceding blister formation. We further identified IL-17 and IL-23 as important molecules favoring IL-1ß expression in monocyte-derived macrophages from BP patients. Finally, we demonstrated the ability of IL-1ß to stimulate the release of the matrix metalloproteinase-9 in those macrophages, reinforcing the role of IL-1ß in the auto-amplification loop of the inflammatory response associated to BP. However, whether this inflammasome is an epiphenomenon associated with BP disease or constitutes an amplification inflammatory step in certain patients still need to be determined. In the context of a precision medicine approach, our findings allowed us to delineate a subgroup of patients with BP that showed similarities with auto-inflammatory diseases. Subsequently, this opens up alternative therapeutic strategies targeting IL-1ß pathway in the aim to control the early, pre-blistering inflammatory phase. Ultimately, this could also help in reducing the detrimental effects associated with high doses of corticosteroids treatment.

Blister Fluid Induces MMP-9-Associated M2-Type Macrophages in Bullous Pemphigoid.

Bullous pemphigoid (BP) is a cutaneous autoimmune disease, characterized by an inflammatory cascade leading to blister formation. Although macrophages were shown to participate in BP pathophysiology, their role in the blister formation process still needs to be investigated. We here addressed the influence of serum and blister fluid (BF) from patients with BP on the polarization status of macrophages with regards to the metalloproteinase-9 (MMP-9) expression. We demonstrated that several markers related to the alternatively activated macrophage phenotype (M2) including IL-10, TARC, arginase, TNFα, and IL-1RA were meaningfully increased in BF of patients with BP. We further showed that BF, but not serum from patients with BP, significantly induced the expression of CD163, CD206, and IL-10 in BP monocyte-derived macrophages (MDMs). Notably IL-10 was the only cytokine to be correlated to the reference clinical score, BP disease activity index (BPDAI), especially to the inflammatory BPDAI subscore evaluating urticarial and erythematous skin lesions (r = 0.57, p = 0.0004). We also found elevated levels of MMP-9 to M2-type macrophages ex vivo and highlighted the presence of CD163+ MMP-9+ macrophages histologically, at skin lesional site. Finally, we showed that methylprednisolone reduced MMP-9 levels in MDMs without modifying the other M2 markers. All together these results strongly support the presence of M2-phenotype macrophages with pro-inflammatory properties susceptible to favor blister formation in BP.