No abstract

Ideal agents for the topical treatment of skin wounds should have antimicrobial efficacy without negative influence on wound healing. Octenidine (OCT) has become a widely used antiseptic in professional wound care, but its influence on several components of the wound healing process remains unclear. In the present study, we have used a superficial wound model using tape stripping on human full-thickness skin ex vivo to investigate the influence of OCT on epidermal Langerhans cells (LCs) and cytokine secretion pattern of skin cells during wound healing in a model without disruption of the normal skin structure. Histological and immunofluorescence studies showed that OCT neither altered human skin architecture nor the viability of skin cells upon 48 hours of culture in unwounded or wounded skin. The epidermis of explants and LCs remained morphologically intact throughout the whole culture period upon OCT treatment. OCT inhibited the upregulation of the maturation marker CD83 on LCs and prevented their emigration in wounded skin. Furthermore, OCT reduced both pro- and anti-inflammatory mediators (IL-8, IL-33, and IL-10), while angiogenesis and growth factor mediators (VEGF and TGF-β1) remained unchanged in skin explant cultures. Our data provide novel insights into the host response to OCT in the biologically relevant environment of viable human (wounded) skin.

Together with keratinocytes (KCs) and the dense network of Langerhans cells (LCs), the epidermis is an ideal portal for vaccine delivery. Pattern recognition receptor agonists, in particular polyinosinic–polycytidylic acid [p(I:C)], are promising adjuvant candidates for therapeutic vaccination to generate protective T-cell immunity. Here we established an ex vivo skin explant model to study the expression and activation of double-stranded RNA (dsRNA)-sensing pattern recognition receptors in LCs and KCs in human skin. Whereas KCs expressed all known dsRNA sensing receptors at a constitutive and inducible level, LCs exclusively expressed melanoma differentiation–associated protein 5 (MDA5) in untreated skin and freshly isolated cells. Comparative assessments of downstream signaling pathways induced by p(I:C) revealed distinct mitochondrial antiviral-signaling protein, IFN-regulatory factor 3, and NF-κB activation in LCs and KCs. Consequently, p(I:C) treatment of LCs significantly induced IFN-α and IFN-β mRNA expression, while in KCs an up-regulation of IFN-β and TNF-α mRNA was detectable. Stimulation of LCs with specific ligands revealed that not the TLR3- but only the MDA5-specific ligand induced IFN-α2, IFN-β, and TNF-α cytokines, but no IL-6 and -8. In KCs, both ligands induced production of high IL-6 and IL-8 levels, and low IFN-α2 and IFN-β levels, indicating that different dsRNA-sensing receptors and/or downstream signaling pathways are activated in both cell types. Our data suggest that MDA5 may be an attractive adjuvant target for epicutaneous delivery of therapeutic vaccines with the goal to target LCs.—Tajpara, P., Schuster, C., Schön, E., Kienzl, P., Vierhapper, M., Mildner, M., Elbe-Bürger, A. Epicutaneous administration of the pattern recognition receptor agonist polyinosinic–polycytidylic acid activates the MDA5/MAVS pathway in Langerhans cells.

In the present study, post-treatment effects of dietary turmeric on markers related to apoptosis, cell proliferation, and inflammation in 7,12-dimethylbenz(a)anthracene (DMBA)-induced hamster buccal pouch (HBP) tumors were investigated. Tumors were induced by applying 0.5% DMBA topically to the HBP three times per week for 12 weeks. After tumor development, half of the animals continued on the control diet and the other half were shifted to a 1% turmeric diet for 4 weeks. To rule out DMBA discontinuation as a cause of inhibition in tumor growth, DMBA treatment was continued during dietary exposure of turmeric in another set of animals until the end of the experiment. The turmeric diet inhibited tumor growth in animals with or without DMBA carcinogen treatment compared to the animals on the control diet. When compared to hamsters bearing tumors that remained on the control diet, the buccal pouches of hamsters bearing tumors receiving turmeric showed the following results: (1) decreased cell proliferation (diminished PCNA, cyclin D1, and Bcl-2) and PCNA labelling index, (2) enhanced apoptosis (increased Bax, caspase-3, caspase-9, and cytochrome c, and decreased survivin) and apoptotic index, (3) decreased inflammation (decreased Cox-2), and (4) decreased MAPK activation (p-ERK and p-p38). These data indicate that tumor growth decreased due to the modulation of cellular pathways associated with cell proliferation and apoptosis.