Potential Pathogenetic Role of Antimicrobial Peptides Carried by Extracellular Vesicles in an in vitro Psoriatic Model.

Purpose: Extracellular Vesicles (EVs) are a heterogeneous group of cell-derived membranous nanoparticles involved in several physiopathological processes. EVs play a crucial role in the definition of the extracellular microenvironment through the transfer of their cargo. Psoriasis is a prototypical chronic inflammatory disease characterized by several secreted mediators, among which antimicrobial peptides (AMPs) are considered pivotal in the development of the psoriatic inflammatory microenvironment. The role of EVs in the pathogenesis of psoriasis has not been elucidated yet, even if emerging evidence demonstrated that interleukin-17A (IL-17A), the psoriasis-related principal cytokine, modifies EVs release and cargo content. The aim of this work was to analyze whether, besides IL-17A, other psoriasis-related cytokines (ie, IFN-γ, TNF-α, IL-22 and IL-23) could affect EVs release and their AMPs mRNAs cargo as well as to analyze the potential biological effect due to EVs internalization by different acceptor cells. Methods: Nanoparticle tracking analysis (NTA) was performed on supernatants of HaCaT cells stimulated with IL-17A, IFN-γ, TNF-α, IL-22 or IL-23 to enumerate EVs. Real-Time RT-PCR was used for gene expression analysis in cells and EVs. Confocal microscopy and Flow cytometry were used to, respectively, study Netosis and EVs internalization. Results: IL-17A and IFN-γ increased EVs release by HaCaT cells. All the tested cytokines modulated AMPs mRNA expression in parental cells and in their respective EVs. S100A12 and hBD2 mRNAs were upregulated following IL-17A and IL-22 treatments. Interestingly, EVs derived from cytokine treated HaCaT cells induced Netosis in freshly isolated neutrophils. Upregulation of S100A12 and hBD2 mRNA was also detectable in acceptor cells incubated with EVs derived from cells treated with psoriasis-related cytokines. Conclusion: The obtained results highlighted the role of EVs in the composition of psoriasis-associated secretome and microenvironment also suggesting the EV involvement in the spreading of the disease mediators and in the possible associated comorbidities.

Reduced Interleukin-17-Expressing Cells in Cutaneous Melanoma.

Characterization of tumor associated lymphocytes (TILs) in tumor lesions is important to obtain a clear definition of their prognostic value and address novel therapeutic opportunities. In this work, we examined the presence of T helper (Th)17 lymphocytes in cutaneous melanoma. We performed an immunohistochemical analysis of a small cohort of primary melanomas, retrospectively selected. Thereafter, we isolated TILs from seven freshly surgically removed melanomas and from three basal cell carcinomas (BCC), as a comparison with a non-melanoma skin cancer known to retain a high amount of Th17 cells. In both studies, we found that, differently from BCC, melanoma samples showed a lower percentage of Th17 lymphocytes. Additionally, TIL clones could not be induced to differentiate towards the Th17 phenotype in vitro. The presence or absence of Th17 cells did not correlate with any patient characteristics. We only observed a lower amount of Th17 cells in samples from woman donors. We found a tendency towards an association between expression by melanoma cells of placenta growth factor, angiogenic factors able to induce Th17 differentiation, and presence of Th17 lymphocytes. Taken together, our data indicate the necessity of a deeper analysis of Th17 lymphocytes in cutaneous melanoma before correlating them with prognosis or proposing Th17-cell based therapeutic approaches.

Interleukin (IL)-17/IL-36 axis participates to the crosstalk between endothelial cells and keratinocytes during inflammatory skin responses.

In inflammatory skin conditions, such as psoriasis, vascular enlargement is associated with endothelial cell proliferation, release of cytokines and adhesion molecule expression. Interleukin (IL)-17A is a pro-inflammatory cytokine mainly secreted by T helper-17 cells that is critically involved in psoriasis pathogenesis. IL-36α, IL-36ß and IL-36γ are also inflammatory cytokines up-regulated in psoriasis and induced by various stimuli, including IL-17A. In this study, we found that human keratinocytes are the main source of IL-36, in particular of IL-36γ. This cytokine was strongly induced by IL-17A and, together with IL-17A, efficiently activated human dermal microvascular endothelial cells (HDMECs), which expressed both IL-17 and IL-36 receptors. Both IL-36γ and IL-17A induced cell proliferation through specific molecular cascades involving ERK1/2 only or ERK1/2, STAT3 and NF-κB, respectively. We highlighted the intense IL-17A- and IL-36γ -dependent interplay between keratinocytes and HDMECs, likely active in the psoriatic lesions and leading to the establishment of a cytokine network responsible for the development and maintenance of the inflamed state. IL-17A or IL-36γ showed in HDMECs a synergic activity with TNF-α by potently inducing inflammatory cytokine/chemokine release and ICAM-1 expression. We also investigated the involvement of IL-36γ and VEGF-A, substantially reduced in lesional skin of psoriatic patients pharmacologically treated with the anti-IL-17A antibody Secukinumab. Importantly, keratinocyte-derived IL-36γ represented an additional pro-angiogenic mediator of IL-17A. We observed that keratinocyte-derived VEGF-A influenced proliferation but did not act on expression of adhesion molecules in HDMECs. On the other hand, inhibition of IL-36γ released by IL-17A-treated keratinocytes impaired either proliferation or ICAM-1 expression both in HDMECs and in an in vivo murine model of psoriasis. Taken together, our data demonstrated that IL-17A and IL-36γ are highly involved in endothelial cells/keratinocytes crosstalk in inflammatory skin conditions.

Human Papillomavirus and carcinogenesis: Novel mechanisms of cell communication involving extracellular vesicles.

A small group of mucosal Human Papillomaviruses are the causative agents of cervical cancer and are also associated with other types of cancers. Certain cutaneous Human Papillomaviruses seem to have a role as co-factors in the UV-induced carcinogenesis of the skin. The main mechanism of the tumorigenesis induced by Human Papillomaviruses is linked to the transforming activity of the viral E6 and E7 oncoproteins. However, other mechanisms, such as the gene expression control by specific microRNAs expression and deregulation of immune inflammatory mediators, may be important in the process of transformation. In this context, the release of Extracellular Vesicles with a specific cargo (microRNAs involved in tumorigenesis, mRNAs of viral oncoproteins, cytokines, chemokines) appears to play a key role.

Eosin treatment for psoriasis reduces skin leukocyte infiltration and secretion of inflammatory chemokines and angiogenic factors.

BACKGROUND: Eosin has been traditionally employed as a topical treatment for psoriasis, but the biological mechanism of its therapeutic action has not been fully elucidated. OBJECTIVES: To analyse eosin effects on psoriatic skin in vivo and keratinocytes and endothelial cells in vitro. MATERIALS & METHODS: Skin biopsies were taken from psoriatic plaques before and after a three-day eosin treatment and processed for histological analysis. Cultured human psoriatic keratinocytes and dermal endothelial cells were treated with eosin, and release of inflammatory chemokines was analysed by multiplexed bead-based immunoassay and ELISA. RESULTS: In patients, the three-day eosin treatment significantly reduced the number of infiltrating T lymphocytes, neutrophilic granulocytes, and dermal dendritic cells. A reduction in VEGF-A expression was also observed. In vitro, eosin treatment significantly decreased the release of CCL2, CCL5, and VEGF-A by keratinocytes and angiopoietin-2 by endothelial cells. CONCLUSIONS: Eosin treatment impacts on psoriatic inflammatory infiltrates and dampens the release of proinflammatory chemokines and angiogenic factors.

Wounds Difficult to Heal: An Effective Treatment Strategy.

OBJECTIVE: Treatment of wounds difficult to heal concerns 50% of the elderly population in Italy and is therefore a relevant social burden. The present study shows how the treatment with autologous leuco-platelets reduces the healing time of wounds improving the functional recovery. PATIENTS AND METHODS: Patients (n=100) with ulcers of the legs were divided in two groups: 1) 50 patients treated with conventional therapies; 2) 50 patients treated with autologous leuco-platelet concentrate (LPC) and hyaluronic acid (HIAFF, Hyalofill-F® ) as a scaffold. RESULTS: After 2 months, a 49% reduction in wound area was observed in the second group and in about 65% wound reduction was achieved in 15 days (4 LPC dressings). In contrast, patients treated by conventional therapies, showed a longer healing time and a greater percentage of failures. Morphometric analysis of biopsy samples obtained from the edge as well as from the bottom of the lesions obtained from the LPC group, detected an abundant presence of neoformed capillaries, characterized by a cubic, "reactive endothelium", close to the site of LPC infiltration. CONCLUSION: These results suggest that healing was promoted not only by limiting bacterial infections but also by the release of chemotactic and proangiogenic factors from leukocytes and platelets, improving the neoformation of capillaries.