CD56 highCD16 - NK cell involvement in cutaneous lichen planus.

Lichen planus is an inflammatory disease of the skin and mucous membranes characterized by vacuolization of basal keratinocytes associated with a prominent junctional lymphocyte infiltrate which comprises T lymphocytes, NK cells, myeloid and plasmacytoid dendritic cells. Basal keratinocyte damage is considered as being a consequence of a lymphocytic cytotoxic attack, mostly mediated by perforin+CD8+ T lymphocytes. NK cells have been described to infiltrate inflamed skin and significantly contribute to the amplification of immune-mediated skin diseases, thanks to their cytotoxic activity and the release of pro-inflammatory cytokines. Here, we investigated the characteristics and functional properties of NK lymphocytes involved in lichen planus. Double staining immunohistochemistry showed a considerable number (6.42 ± 2.2% of the total cellular infiltrate) of CD3-CD56+ cells in early lichen planus lesions, mostly distributed in the papillary dermis and at the epidermal-dermal interface. Skin NK cells isolated from lichen planus lesions belong to the CD56highCD16- subset, are highly positive for perforin and natural cytotoxic receptors NKG2D and NKp44, and, in accordance with their phenotype, are negative for KIRs receptors CD158a and CD158b. Skin CD56highCD16- NK cells display a CCR6+CXCR3+CCR5+ChemR23+ chemokine receptor asset for homing into inflamed skin. In terms of cytokine release, skin CD56highCD16- NK cells are able to secrete IFN-γ, TNF-α and hardly release IL-22, IL-17 and IL-4. Overall, our data propose a pro-inflammatory role of NK lymphocytes in lichen planus.

Osteopontin: a new emerging role in psoriasis.

Osteopontin (OPN) is a phosphorylated acidic glycoprotein produced by cells of the immune system, epithelial tissue, smooth muscle cells, osteoblasts, and tumor cells. OPN interacts with integrins and CD44 to enhance Th1 and inhibit Th2 cytokine expression. The involvement of this molecule in the onset of psoriasis has not previously been studied. Here, we demonstrate that OPN is expressed in peripheral blood mononuclear cells and in skin biopsies of psoriatic patients. The study was conducted on 30 patients affected with plaque psoriasis, and on 11 healthy donors. Two blood samples and two skin samples from patients affected with atopic dermatitis were used as control for Th2 typical inflammatory skin disease. The analysis of IL-1beta, IFN-gamma, TauNuF-alpha, IL-8, and ICAM-1 showed the characteristic Th1 pattern in all the psoriatic blood and skin samples analyzed. This study offers an opportunity for understanding inflammation in psoriasis and supports the hypothesis that OPN could represent a potential target for therapeutic intervention in psoriatic patients.

5-aminolaevulinic acid and photodynamic therapy reduce HSV-1 replication in HaCat cells through an apoptosis-independent mechanism.

BACKGROUND: Photodynamic therapy (PDT) involves the use of a photosensitizing agent, which may require metabolic synthesis (i.e. a prodrug), followed by light activation. Numerous studies have advanced PDT as a means for treating bacteria, fungi and viruses. In this study, the photoinactivation of Herpes simplex virus type 1 (HSV-1) in human keratinocytes using 5-aminolaevulinic acid (5-ALA) was investigated. METHODS: HaCat cells were infected with HSV-1 and treated with 5-ALA to verify its antiviral effect during the stages of adsorption and penetration to host cells. Immunoblot analysis was used to estimate the effect of ALA-PDT on the production of viral proteins glycoprotein D (gD), infected cell proteins (ICP) 27 and virion protein (VP) 16. We also investigated whether the effect of ALA-PDT was associated with a cellular apoptotic mechanism through DNA fragmentation and the study of p53, PARP and caspase-3 protein expression. RESULTS: While the treatment of ALA-PDT after the viral adsorption period reduced HSV-1 replication by about 70%, it did not act on the virus in the first phase of infection. The viral proteins' expressions were reduced by ALA-PDT treatments. There was no evidence of ALA-PDT-induced apoptosis. CONCLUSION: Our data suggest that the target of photoinactivation appears to be viral replication and not a cellular response.