Martine Garcia

IL-22 inhibits epidermal differentiation and induces proinflammatory gene expression and migration of human keratinocytes

IL-22 belongs to a family of cytokines structurally related to IL-10, including IL-19, IL-20, IL-24, and IL-26. In contrast to IL-10, IL-22 has proinflammatory activities. IL-22 signals through a class II cytokine receptor composed of an IL-22-binding chain, IL-22RA1, and the IL-10RB subunit, which is shared with the IL-10R. In the present study, we show that short-term cultured human epidermal keratinocytes express a functional IL-22R but no IL-10R. Accordingly, IL-22 but not IL-10 induces STAT3 activation in keratinocytes. Using a cDNA array screening approach, real-time RT-PCR, and Western blot analysis, we demonstrate that IL-22 up-regulates, in a dose-dependent manner, the expression of S100A7, S100A8, S100A9, a group of proinflammatory molecules belonging to the S100 family of calcium-binding proteins, as well as the matrix metalloproteinase 3, the platelet-derived growth factor A, and the CXCL5 chemokine. In addition, IL-22 induces keratinocyte migration in an in vitro injury model and down-regulates the expression of at least seven genes associated with keratinocyte differentiation. Finally, we show that IL-22 strongly induces hyperplasia of reconstituted human epidermis. Taken together, these results suggest that IL-22 plays an important role in skin inflammatory processes and wound healing.

A role for T cell-derived interleukin 22 in psoriatic skin inflammation.

Interleukin (IL)‐22 is a T cell‐derived cytokine that has been reported recently to induce cutaneous inflammation in an experimental murine model of psoriasis, and to induce in vitro an inflammatory‐like phenotype. In the present study, we assessed the presence of IL‐22 and the IL‐22 receptor 1 (IL‐22R1) in skin lesions, skin‐derived T cells, as well as IL‐22 levels in sera from patients with psoriasis. IL‐22R1 and IL‐10R2 transcripts are expressed at a similar level in psoriatic and healthy skin. In contrast, IL‐22 mRNA expression was up‐regulated in psoriatic skin lesions compared to normal skin, whereas IL‐22 mRNA levels in peripheral blood mononuclear cells from psoriatic patients and normal subjects were similar. Circulating IL‐22 levels were significantly higher in psoriatic patients than in normal subjects. T cells isolated from psoriatic skin produced higher levels of IL‐22 in comparison to peripheral T cells isolated from the same patients. IL‐10 was expressed at similar levels in skin biopsies and peripheral blood mononuclear cells of psoriatic patients and normal subjects. Finally, we show here that supernatants of lesional psoriatic skin‐infiltrating T cells induce an inflammatory response by normal human epidermal keratinocytes, resembling that observed in psoriatic lesions. Taken together, the results reported in this study indicate that IL‐22 is a cytokine produced by skin‐infiltrating lymphocytes that is potentially involved in initiation and/or maintenance of the pathogenesis of psoriasis.

Oncostatin M Secreted by Skin Infiltrating T Lymphocytes Is a Potent Keratinocyte Activator Involved in Skin Inflammation

Cutaneous inflammatory diseases such as psoriasis vulgaris and atopic dermatitis are associated with altered keratinocyte function, as well as with a particular cytokine production profile of skin-infiltrating T lymphocytes. In this study we show that normal human epidermal keratinocytes express a functional type II oncostatin-M (OSM) receptor (OSMR) consisting of the gp130 and OSMRβ components, but not the type I OSMR. The type II OSMR is expressed in skin lesions from both psoriatic patients and those with atopic dermatitis. Its ligand, OSM, induces via the recruitment of the STAT3 and MAP kinase pathways a gene expression profile in primary keratinocytes and in a reconstituted epidermis that is characteristic of proinflammatory and innate immune responses. Moreover, OSM is a potent stimulator of keratinocyte migration in vitro and increases the thickness of a reconstituted epidermis. OSM transcripts are enhanced in both psoriatic and atopic dermatitic skin as compared with healthy skin and mirror the enhanced production of OSM by T cells isolated from diseased lesions. Results from a microarray analysis comparing the gene-modulating effects of OSM with those of 33 different cytokines indicate that OSM is a potent keratinocyte activator similar to TNF-α, IL-1, IL-17, and IL-22 and that it acts in synergy with the latter cytokines in the induction of S100A7 and β-defensin 2 expression, characteristic of psoriatic skin. Taken together, these results demonstrate that OSM and its receptor play an important role in cutaneous inflammatory responses in general and that the specific effects of OSM are associated with distinct inflammatory diseases depending on the cytokine environment.

Human cardiomyocyte hypertrophy induced in vitro by gp130 stimulation

OBJECTIVES Recent in vivo and in vitro studies in animals have demonstrated that cytokines of the IL-6 family are involved in cardiac hypertrophy and in protection of cardiomyocytes against apoptosis. The present study aims to analyse the capacity of human atrial cardiac cells (i.e., cardiomyocytes and fibroblasts) to display the gp130 receptor subunit, and to evaluate its functionality. METHODS Twenty human atrial biopsies were used for immunohistochemistry, in situ hybridisation, and western blot analysis or dissociated for isolation and primary culture of cardiac cells. RESULTS Fibroblasts present in tissue or maintained in primary culture clearly express gp130 whereas the signal in cardiomyocytes is weaker. Culture of cardiac cells with a gp130 agonist antibody enhances atrial natriuretic peptide (ANP), beta myosin heavy chain (beta-MHC) expression in cardiomyocytes, and significantly increases the cell surface area microm(2)). This process could involve STAT3 (signal transducer and activator of transcription 3) phosphorylation. CONCLUSIONS These results demonstrate that gp130 activation in human cardiac cells leads to cardiomyocyte hypertrophy. We discuss several hypotheses on the role of IL-6-type cytokines on cardiomyocyte functions.

Involvement of IL-1 and Oncostatin M in Acanthosis Associated With Hypertensive Leg Ulcer

Hypertensive leg ulcer (HLU) is an inflammatory disease characterized by intense pain, alteration of vascularization, and skin necrosis. The optimal treatment relies on surgical removal of necrotic tissues covered by a split-skin graft. We studied the histomorphology of the lesions and investigated the involvement of inflammatory cells and cytokines to further define the physiopathology of HLU. We report epidermis acanthosis and a preferential occlusion of the precapillary arterioles with infiltration of neutrophils, macrophages, and T lymphocytes in the dermis. OSM, IL-1β, and IL-6 were overexpressed in the ulcer, whereas the Th17-derived cytokines were not. In vitro, the addition of IL-1β and OSM promoted acanthosis and destructuring of reconstructed epidermis. Exogenous IL-1β and OSM synergistically induced epidermal acanthosis in mice. These data show that OSM and IL-1β are not only a biological characteristic signature of HLU, but these cytokines reflect a specific inflammatory state, directly involved in the pathogenesis. We suggest that anti-cytokine biotherapies could be an alternative strategy to surgery to treat HLU.

Interleukin-17A-induced production of acute serum amyloid A by keratinocytes contributes to psoriasis pathogenesis

Background Acute-serum Amyloid A (A-SAA), one of the major acute-phase proteins, is mainly produced in the liver but extra-hepatic synthesis involving the skin has been reported. Its expression is regulated by the transcription factors NF-κB, C/EBPβ, STAT3 activated by proinflammatory cytokines. Objectives We investigated A-SAA synthesis by resting and cytokine-activated Normal Human Epidermal Keratinocytes (NHEK), and their inflammatory response to A-SAA stimulation. A-SAA expression was also studied in mouse skin and liver in a model mimicking psoriasis and in the skin and sera of psoriatic and atopic dermatitis (AD) patients. Methods NHEK were stimulated by A-SAA or the cytokines IL-1α, IL-17A, IL-22, OSM, TNF-α alone or in combination, previously reported to reproduce features of psoriasis. Murine skins were treated by imiquimod cream. Human skins and sera were obtained from patients with psoriasis and AD. A-SAA mRNA was quantified by RT qPCR. A-SAA proteins were dosed by ELISA or immunonephelemetry assay. Results IL-1α, TNF-α and mainly IL-17A induced A-SAA expression by NHEK. A-SAA induced its own production and the synthesis of hBD2 and CCL20, both ligands for CCR6, a chemokine receptor involved in the trafficking of Th17 lymphocytes. A-SAA expression was increased in skins and livers from imiquimod-treated mice and in patient skins with psoriasis, but not significantly in those with AD. Correlations between A-SAA and psoriasis severity and duration were observed. Conclusion Keratinocytes could contribute to psoriasis pathogenesis via A-SAA production, maintaining a cutaneous inflammatory environment, activating innate immunity and Th17 lymphocyte recruitment.

Specific Anti-Leukemic Activity of the Peptide Warnericin RK and Analogues and Visualization of Their Effect on Cancer Cells by Chemical Raman Imaging

Antimicrobial peptides can be used as therapeutic agents against cancer cells. Warnericin RK and derivatives (WarnG20D and WarnF14V) were tested on various, solid tumor or leukemia, cancer cells. These peptides appeared to be cytotoxic on all the cell types tested, cancerous as well healthy, but very interestingly displayed no deleterious effect on healthy mononuclear cells. The mode of action of the peptide was proposed to be membranolytic, using chemical Raman imaging. Addition of peptide induced a large disorganization of the membrane leading to the loss of the content of inner compartments of Jurkat cell, whereas no effect was observed on the healthy mononuclear cells. The less hemolytic peptides WarnG20D and WarnF14V could be good candidates for the leukemia treatment.