IL-17A Dissociates Inflammation from Fibrogenesis in Systemic Sclerosis.

IL-17A is abundant in scleroderma but its role in fibrogenesis is controversial. We interrogated the role of IL-17A in extracellular matrix deposition and inflammation by investigating its effects on keratinocytes and fibroblasts cross-talk and in organotypic skin cultures. Keratinocyte-conditioned media of resting, IL-17A-, and/or transforming growth factor-ß-primed primary keratinocytes were used to stimulate healthy donors and scleroderma fibroblasts. Alternatively, organotypic cultures of full human skin were challenged with these cytokines. Keratinocyte-conditioned media tilted the balance of col-I to matrix metalloproteinase-1 production by fibroblasts in favor of matrix metalloproteinase-1, significantly more so in healthy donors than in scleroderma, resulting in enhanced extracellular matrix turnover, further increased by IL-17A. In organotypic skin, transforming growth factor-ß induced an extensive pro-fibrotic gene signature, including the enhanced expression of several collagen genes associated with Wnt signaling. IL-17A strongly promoted the expression of pro-inflammatory genes, with no direct effects on collagen genes, and attenuated Wnt signaling induced by transforming growth factor-ß. In this model, at the protein level, IL-17A significantly decreased col-I production. Our data strongly support a pro-inflammatory and antifibrogenic activity of IL-17A in the context of keratinocyte-fibroblast interaction and in full skin. These data help in directing and interpreting targeted therapeutic approaches in scleroderma.

IL-17E (IL-25) Enhances Innate Immune Responses during Skin Inflammation.

IL-17E (IL-25) is a member of the IL-17 cytokine family involved in the promotion of type 2 immune responses. Recently, IL-17E has been reported to be up-regulated in distinct skin inflammatory diseases such as psoriasis and atopic and contact dermatitis. We assessed the role played by IL-17E in skin inflammation. Here, we show that IL-17E induces skin inflammation in vivo, characterized by the expression of innate immune response genes and the recruitment of innate immune cells, particularly neutrophils. Genetic deletion or IL-17E neutralization ameliorated skin inflammation induced by imiquimod application or tape stripping, with reductions in neutrophil and macrophage infiltration as assessed by t-distributed stochastic neighbor embedding-guided multiparameter flow cytometry analysis, in mice. In humans, IL-17E promotes the recruitment of neutrophils via activation of macrophages in a p38-dependent mechanism. In addition, IL-17E is up-regulated in neutrophil-rich inflammatory skin diseases, such as pyoderma gangrenosum and acute generalized exanthematous pustulosis. Our data show a role for IL-17E in skin inflammation that is unrelated to the development of type 2 immune reactions. We propose that IL-17E is an important common denominator of chronic skin inflammation, promoting innate immune cell recruitment and activation.

Cell therapy in surgical treatment of fistulas. Preliminary results.

Risk of recurrence after surgical treatment of a recurrent fistula is up to 50%. It has be known that more aggressive surgical treatment is associated with a high risk of anal sphincter damage and leads to incontinence. Several studies have been designed to elaborate minimally invasive treatment of rectovaginal and anal fistulas. The properties of Adipose-derived Stem Cells (ASC) significantly enhance a natural healing potency. Here, we present our experience with combined surgical and cell therapy in the treatment of fistulas. MATERIALS AND METHODS: Four patients were enrolled in our study after unsuccessful treatments in the past - patients 1-3 with rectovaginal fistulas including two women after graciloplasty, and patient 4 - a male with complex perianal fistula. Adipose tissue was obtained from subcutaneous tissue. ASCs were isolated, cultured up to 10+/-2 mln cells and injected into the walls of fistulas. Follow-up physical examination and anoscopy were performed at 1, 4, 8, and 12 weeks, 6 and 12 months after implantation. RESULTS: Up to 8 weeks after ASC implantation, symptoms of fistulas' tracts disappeared. At 8 weeks, in patients 1-3, communication between vaginal and rectal openings was closed and at 12-16 w. intestinal continuity was restored in patient 3 and 4. After a 6-month follow-up, the fistula tract of patient 4 was closed. Up to 12 m. after ASC implantation no recurrences or adverse events were observed. CONCLUSION: ASCs combined with surgical pre-treated fistula tracts were used in four patients. All of them were healed. This encouraging result needs further trials to evaluate the clinical efficiency and the cost-effectiveness ratio.

MCPIP1 contributes to the inflammatory response of UVB-treated keratinocytes.

BACKGROUND: Monocyte chemoattractant protein-1-induced protein-1 (MCPIP1), also known as regnase-1, negatively regulates many cellular processes including the cellular response to inflammatory agents, differentiation, viability, and proliferation. It possesses a PilT N-terminus (PIN) domain that is directly involved in regulating the stability of transcripts and miRNAs by recognizing stem loop structures and degrading them by endonucleolytic cleavage. OBJECTIVE: We investigated the role of MCPIP1 in the response of human primary keratinocytes to UVB stress. METHODS: Keratinocytes were treated with UVB, siRNA against MCPIP1, pharmacological inhibitors of signaling pathways, or subjected to control treatments. The mRNA and protein levels of MCPIP1 and MCPIP1-dependent changes gene expression were analyzed by quantitative (Q)-RT-PCRs and Western blots. Secretion of TNFα and IL-8 was determined by ELISA. RESULTS: UVB treatment of keratinocytes induced upregulation of MCPIP1 at the mRNA level after 4-8h and at the protein level after 8-16h. MCPIP1 abundance depended on NF-κB activity. Using an siRNA strategy, we found that diminished MCPIP1 resulted in an up-regulation of transcripts coding for IL-8, TNFα, COX-2, and BCL-2, as well as an enhanced release of IL-8. Moreover, decreased phosphorylation of NF-κB and p38 signaling pathways were observed in addition to a slight up-regulation of ERK1/2 directly after UVB treatment. Twenty-four hours later, decreased phosphorylation was observed only for NF-κB and p38. Furthermore, in MCPIP1-suppressed cells, the levels of pro-apoptotic Puma, the phosphorylated form of p53 and the abundance of its target p21 as well as the activity of caspase 3 decreased, while the level of cyclin D1 increased. CONCLUSION: MCPIP1 contributes to the UVB response of keratinocytes by altering metabolic and apoptotic processes and the release of inflammatory mediators.

Electric field as a potential directional cue in homing of bone marrow-derived mesenchymal stem cells to cutaneous wounds.

Bone marrow-derived cells are thought to participate and enhance the healing process contributing to skin cells or releasing regulatory cytokines. Directional cell migration in a weak direct current electric field (DC-EF), known as electrotaxis, may be a way of cell recruitment to the wound site. Here we examined the influence of electric field on bone marrow adherent cells (BMACs) and its potential role as a factor attracting mesenchymal stem cells to cutaneous wounds. We observed that in an external EF, BMAC movement was accelerated and highly directed with distinction of two cell populations migrating toward opposite poles: mesenchymal stem cells migrated toward the cathode, whereas macrophages toward the anode. Analysis of intracellular pathways revealed that macrophage electrotaxis mostly depended on Rho family small GTPases and calcium ions, but interruption of PI3K and Arp2/3 had the most pronounced effect on electrotaxis of MSCs. However, in all cases we observed only a partial decrease in directionality of cell movement after inhibition of certain proteins. Additionally, although we noticed the accumulation of EGFR at the cathodal side of MSCs, it was not involved in electrotaxis. Moreover, the cell reaction to EF was very dynamic with first symptoms occurring within <1min. In conclusion, the physiological DC-EF may act as a factor positioning bone marrow cells within a wound bed and the opposite direction of MSC and macrophage movement did not result either from utilizing different signalling or redistribution of investigated cell surface receptors.