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We have recently shown that fluoxetine (FX) suppressed polyinosinic-polycytidylic acid-induced inflammatory response and endothelin release in human epidermal keratinocytes, via the indirect inhibition of the phosphoinositide 3-kinase (PI3K)-pathway. Because PI3K-signaling is a positive regulator of the proliferation, in the current, highly focused follow-up study, we assessed the effects of FX (14 µM) on the proliferation and differentiation of human epidermal keratinocytes. We found that FX exerted anti-proliferative actions in 2D cultures (HaCaT and primary human epidermal keratinocytes [NHEKs]; 48- and 72-h; CyQUANT-assay) as well as in 3D reconstructed epidermal equivalents (48-h; Ki-67 immunohistochemistry). Importantly, FX did not influence epidermal thickness (hematoxylin-eosin staining), and it did not have a major impact on the differentiation-associated alteration of the gene expression pattern (24-h treatments; RNA-Seq). Moreover, neither keratin (K)-1, nor K10 expression was altered by FX in NHEKs (RT-qPCR) or in 3D epidermal equivalents (semi-quantitative immunohistomorphometry). FX did not influence differentiation-induced up-regulation of occludin (RT-qPCR; NHEKs), and did not alter differentiation-associated barrier forming capacity of epidermal keratinocytes (electrical impedance; Lucifer Yellow penetration assay). Our data indicate that, besides the previously reported combined anti-inflammatory and putative anti-pruritic effects, FX may also suppress proliferation of human epidermal keratinocytes without impairing their differentiation and barrier-forming capacity. [ABSTRACT FROM AUTHOR]

Fluoxetine is a safe antidepressant with remarkable anti‐inflammatory actions; therefore, we aimed to investigate its effects on immortalized (HaCaT) as well as primary human epidermal keratinocytes in a polyinosinic‐polycytidylic acid (p(I:C))‐induced inflammatory model. We found that a non‐cytotoxic concentration (MTT‐assay, CyQUANT‐assay) of fluoxetine significantly suppressed p(I:C)‐induced expression and release of several pro‐inflammatory cytokines (Q‐PCR, cytokine array, ELISA), and it decreased the release of the itch mediator endothelins (ELISA). These effects were not mediated by the inhibition of the NF‐κB or p38 MAPK pathways (western blot), or by the suppression of the p(I:C)‐induced elevation of mitochondrial ROS production (MitoSOX Red labeling). Instead, unbiased activity profiling revealed that they were most likely mediated via the inhibition of the phosphoinositide 3‐kinase (PI3K) pathway. Importantly, the PI3K‐inhibitor GDC0941 fully mimicked the effects of fluoxetine (Q‐PCR, ELISA). Although fluoxetine was able to occupy the binding site of GDC0941 (in silico molecular docking), and exerted direct inhibitory effect on PI3K (cell‐free PI3K activity assay), it exhibited much lower potency and efficacy as compared to GDC0941. Finally, RNA‐Seq analysis revealed that fluoxetine deeply influenced the transcriptional alterations induced by p(I:C)‐treatment, and exerted an overall anti‐inflammatory activity. Collectively, our findings demonstrate that fluoxetine exerts potent anti‐inflammatory effects, and suppresses the release of the endogenous itch mediator endothelins in human keratinocytes, most likely via interfering with the PI3K pathway. Thus, clinical studies are encouraged to explore whether the currently reported beneficial effects translate in vivo following its topical administration in inflammatory and pruritic dermatoses. [ABSTRACT FROM AUTHOR]

This prospective, 4‐week, placebo‐controlled, cross‐over study aimed to investigate the efficacy of 1% topical κ‐opioid agonist, asimadoline, in a model of canine atopic dermatitis (AD). Fourteen beagles were challenged with house dust mites every 3–4 days for a total of 9 challenges. Severity of dermatitis was assessed, and pruritus was monitored using GoPro HERO cameras. Pruritus scoring was evaluated at 10 time periods; baseline, 4 h post allergen challenge and the last day of the study on Day 28. Scoring was done blindly by personnel using BORIS software. A global subjective score was also given using a visual analogue scale (VAS). A 4‐week washout period occurred and dogs were crossed‐over, the study was repeated, and the results were analysed using combined data. Gel was applied once daily on inguinal area (0.6 ml/dog). ANOVA showed significant effect of time (p < 0.0001) and group (p = 0.0001) on dermatitis scores. Overall, no statistically significant effect on pruritus was found due to a crossing of scores on Day 17. Overtime the placebo scores increased while the active ingredient showed decrease after first 3 weeks. It is concluded that this approach is promising in dogs with AD and longer studies with more frequent application may be beneficial. [ABSTRACT FROM AUTHOR]

Psoriasis is a chronic inflammatory disease appearing as scaly erythematous cutaneous lesions, which are characterized by parakeratosis and acanthosis as well as the infiltration of immune cells, such as T helper-1 and T helper-17 cells. Here, we demonstrated that Kd PT, a tripeptide structurally related to the C-terminal amino acids of alpha-melanocyte-stimulating hormone, which was previously shown to exhibit anti-inflammatory effects in intestinal inflammation, ameliorated ongoing disease in the mouse model of imiquimod-induced psoriasis-like skin inflammation and in the small xenotransplant mouse model of psoriasis. We could show that systemic Kd PT treatment significantly reduced hyperkeratosis and acanthosis in murine as well as human skin. Moreover, Kd PT upregulated Foxp3 in CD4+ T cells from mice and from peripheral blood of individuals with psoriasis and decreased the expression of type 1 inflammatory cytokines, indicating that the beneficial effect of Kd PT was, at least in part, mediated by the induction of functional regulatory T cells that suppressed the activation of pathogenic CD4+ IFN-γ+ and CD4+ IL-17+ T cells. Thus, these data might suggest Kd PT as a potential novel therapeutic alternative for the treatment of psoriasis. [ABSTRACT FROM AUTHOR]

In order to develop novel κ agonists restricted to the periphery, a diastereo- and enantioselective synthesis of (4aR,5S,8aS)-configured decahydroquinoxalines 5-8 was developed. Physicochemical and pharmacological properties were fine-tuned by structural modifications in the arylacetamide and amine part of the pharmacophore as well as in the amine part outside the pharmacophore. The decahydroquinoxalines 5-8 show single-digit nanomolar to subnanomolar κ-opioid receptor affinity, full κ agonistic activity in the [35S]GTPγS assay, and high selectivity over μ, δ, σ1, and σ2 receptors as well as the PCP binding site of the NMDA receptor. Several analogues were selective for the periphery. The anti-inflammatory activity of 5-8 after topical application was investigated in two mouse models of dermatitis. The methanesulfonamide 8a containing the (S)-configured hydroxypyrrolidine ring was identified as a potent (K i = 0.63 nM) and highly selective κ agonist (EC50 = 1.8 nM) selective for the periphery with dose-dependent anti-inflammatory activity in acute and chronic skin inflammation. [ABSTRACT FROM AUTHOR]