Zinc Oxide Protects Cultured Enterocytes from the Damage Induced by Escherichia coli

Abstract

There is some evidence that zinc oxide (ZnO) protects against intestinal diseases. However, despite the suggestions that ZnO may have an antibacterial effect, the mechanisms of this protective effect have not yet been elucidated. We investigated the potential benefits of ZnO in protecting intestinal cells from damage induced by enterotoxigenic Escherichia coli (ETEC, strain K88) and the related mechanisms, using human Caco-2 enterocytes. Cell permeability, measured as transepithelial electrical resistance (TEER), was unaffected by 0.01 and 1 mmol/L ZnO treatments and moderately increased by 5 mmol/L ZnO, compared with untreated cells. Transfer of (14)C-inulin was slightly increased by 5 mmol/L ZnO compared with untreated cells; transfer was unaffected by lower concentrations. The TEER and (14)C-inulin transfer were lower in ETEC-infected cells than in uninfected cells. Treatment of ETEC exposure with 0.2 mmol/L ZnO prevented disruption of membrane integrity. The ETEC was able to adhere to enterocytes and, to some extent, invade the cells. The ZnO treatment reduced bacterial adhesion and blocked bacterial invasion. The ETEC infection upregulated the expression of the inflammatory cytokines interleukin-8, growth-related oncogene-alpha and tumor necrosis factor-alpha, and reduced that of the anti-inflammatory cytokine transforming growth factor-beta, compared with uninfected cells. The addition of 0.2 or 1 mmol/L ZnO counteracted the alteration of cytokine mRNA levels caused by ETEC. The protective effects of ZnO were not due to any antibacterial activity, because the viability of ETEC grown in a medium containing ZnO was unaffected. In conclusion, ZnO may protect intestinal cells from ETEC infection by inhibiting the adhesion and internalization of bacteria, preventing the increase of tight junction permeability and modulating cytokine gene expression.

Metalloproteins and phytochelatin synthase may confer protection against zinc oxide nanoparticle induced toxicity in Caenorhabditis elegans

“…Based on the TEM images, ZnONP agglomerates did not seem to induce morphological changes or enter the bacteria. Clearly, high concentrations of ZnONPs may inflict changes to the metabolic system of E. coli, a notion that cannot be assessed by TEM (Roselli et al, 2003;Liu et al, 2009). However, continuous contact with ZnONPs caused the bacteria to secrete extracellular polymeric substances (EPS) which coated the nanoparticles within a 24 hour timeframe (Fig.…”

Dietary phenylalanine-improved intestinal barrier health in young grass carp (Ctenopharyngodon idella) is associated with increased immune status and regulated gene expression of cytokines, tight junction proteins, antioxidant enzymes and related signalling molecules

“…4 6. impaired digestive and absorptive functions as well as antioxidant capacity in the intestines of young grass carp, but all of these negative observations could be improved by optimal Phe supplementation [8]. In poultry, digestive ability and absorption function rely on intestinal health [48].…”

“…Limited research has suggested that nutrient deficiencies can disturb the intestinal mucosal immune system. It was reported that zinc deficiency upregulated the expression of the inflammatory cytokines interleukin-8 (IL-8) and tumour necrosis factor-a (TNF-a) and increased bacterial adhesion in the human colorectal adenocarcinoma cell line Caco-2 in vitro [4]. Meanwhile, vitamin A deficiency caused intestinal epithelium dysfunction and increased bacterial translocation in the intestines of rats [5].…”

Assessing the efficacy of zinc oxide nanoparticles against Penicillium expansum by automated turbidimetric analysis

“…Recently, metal nanoparticles have received increasing attention due to strong antimicrobial properties and low toxicity towards mammalian cells and have been already applied in food preservation, burn dressings, safe cosmetics, medical devices, water treatment and other range of products (Moritz and Geszke-Moritz 2013). Additional benefits coming from the use of inorganic nanoparticles are their improved stability in comparison with the traditional antimicrobial agents (Dutta et al 2012) and some of them even contain mineral elements essential to human (Roselli et al 2003; Espitia et al 2012). The main metal and metal oxide nanoparticles are based on silver, copper, copper oxide and zinc oxide (Moritz and Geszke-Moritz 2013).…”