RESUMEN
BACKGROUND: Macromolecules in skin cells are damaged when exposed to environmental stressors, leading to disrupted cellular function and homeostasis. While epidermal turnover can eliminate some of this damage, autophagy can rapidly remove these defective components. Niacinamide (Nam) is known to induce autophagy and optimizing formulations to maximize this response could provide improved homeostasis in stressed skin. OBJECTIVE: To determine (i) whether Nam can induce autophagy related 5 (ATG5), an autophagy marker, in human keratinocytes and (ii) whether optimized low pH Nam formulations can enhance the response in 3D skin models. METHODS: Human keratinocytes treated with Nam were evaluated for autophagosome accumulation and induction of ATG5 by gene expression, immunoblotting and immune-fluorescence microscopy. 3D skin equivalents were topically treated with Nam formulations at pH 5.8 and 3.8. Gene expression profiling and immunoblot analysis of ATG5 were performed. RESULTS: Nam treatment of keratinocytes led to an accumulation of autophagosomes with a maximal signal at 48 h. Gene expression of ATG5 was induced by Nam, and immunoblots stained for ATG5 showed a significant increase after 6 h of treatment. Gene expression profiling of 3D epidermal skin equivalents treated with Nam at pH 3.8 showed stronger induction of autophagy-related genes, including ATG5, compared with pH 5.8 formulas. Enrichment for gene ontology terms on autophagy showed an increased linkage with Nam formulas at pH 3.8. CONCLUSIONS: We found that Nam induces autophagosome accumulation and ATG5 levels in keratinocytes. We also discovered that a Nam formulation at pH 3.8 can further increase levels of ATG5 in 3D skin models when compared to Nam at pH 5.8. These data support that Nam can induce autophagy in keratinocytes and formulations at pH 3.8 can enhance the impact. We hypothesize that optimized formulations at pH 3.8 can improve skin ageing appearance via autophagy induction.
Asunto(s)
Proteína 5 Relacionada con la Autofagia , Autofagia , Queratinocitos , Niacinamida , Proteína 5 Relacionada con la Autofagia/genética , Expresión Génica , Humanos , Concentración de Iones de Hidrógeno , Queratinocitos/metabolismoRESUMEN
BACKGROUND: Numerous clinical trials evaluating the efficacy of various antimicrobial compounds against Helicobacter pylori infection have been performed in humans. A convenient animal model for Helicobacter infection would facilitate the evaluation of novel therapies. These experiments were performed to evaluate the use of ferrets as a model of Helicobacter infection. MATERIALS AND METHODS: Ferrets were infected experimentally with Helicobacter mustelae and subsequently treated with bismuth subsalicylate (BSS) triple therapy (BSS, metronidazole, and amoxicillin), or left untreated. The status of infection and serology was assessed during treatment and for 8 weeks posttreatment. Seven ferrets successfully treated with triple therapy were challenged with H. mustelae and monitored for infection for an additional 5 weeks. RESULTS: Infection of ferrets by H. mustelae was accompanied by gastritis and a specific antibody response. Treatment of H. mustelae-infected ferrets with BSS suppressed bacterial growth in four of nine animals but did not eradicate infection. Triple therapy eradicated infection in all nine ferrets with a reduction in gastric inflammation. No relapse of infection occurred up to 8 weeks posttherapy. Challenge with H. mustelae of ferrets successfully treated with triple therapy resulted in a 100% rate of reinfection. CONCLUSIONS: H. mustelae infection can be eliminated by triple therapy, but this does not result in protective immunity against reinfection by H. mustelae. This model, using a strain of Helicobacter indigenous to the host, may be useful for assessing therapeutic efficacy of novel therapies for the treatment of human infection by H. pylori.