Botanicals as a zinc oxide alternative to protect intestinal cells from an Escherichia coli F4 infection in vitro by modulation of enterocyte inflammatory response and bacterial virulence

Abstract

Pharmacological doses of zinc oxide (ZnO) have been widely used in pig industry to control post-weaning diarrhea (PWD) symptoms exacerbated by enterotoxigenic Escherichia coli F4 infections. Because of environmental issues and regulatory restrictions, ZnO is no longer sustainable, and novel nutritional alternatives to manage PWD are urgently required. Botanicals represent a wide class of compounds employed in animal nutrition because of their diverse beneficial functions. The aim of this study was to investigate the in vitro protective action of a panel of essential oils and natural extracts on intestinal Caco-2 cells against an E. coli F4 infection. Moreover, we explored the potential mechanisms of action of all the botanicals compared to ZnO. Amongst the others, thyme essential oil, grape seed extract, and Capsicum oleoresin were the most effective in maintaining epithelial integrity and reducing bacterial translocation. Their mechanism of action was related to the modulation of cellular inflammatory response, the protection of tight junctions' expression and function, and the control of bacterial virulence, thus resembling the positive functions of ZnO. Moreover, despite their mild effects on the host side, ginger and tea tree essential oils provided promising results in the control of pathogen adhesion when employed during the challenge. These outcomes support the advantages of employing selected botanicals to manage E. coli F4 infections in vitro, therefore offering novel environmentally-friendly alternatives to pharmacological doses of ZnO capable to modulate host-pathogen interaction at different levels during PWD in pigs.

A blend of selected botanicals maintains intestinal epithelial integrity and reduces susceptibility to Escherichia coli F4 infection by modulating acute and chronic inflammation in vitro

“…The infection protocol was performed according to our previous study (22). Briefly, Caco-2 were differentiated and TER of all inserts measured as described in paragraph 2.3.…”

“…As previously described (22), to assess the ability of BOT to influence bacterial interaction with target cells, Caco-2 were differentiated on 24 well plates. On the infection day, cells were washed twice with DPBS, then infected with 5 × 10 7 CFU/mL ETEC in basal medium without P/S and supplemented with the blend of botanicals (BOT+).…”

“…After the challenge, cells were washed twice with DPBS, and then fixed in 4% paraformaldehyde in DPBS. Staining was performed according to our previous study (22). Briefly, Caco-2 were permeabilized with 0.5% Triton X-100, and subsequently blocked with 10% goat serum.…”

“…Botanicals such as essential oils, oleoresins, and powder extracts are broadly studied in animal nutrition thanks to their recognized antimicrobial, antioxidant, and anti-inflammatory properties (19,20). Our previous studies showed that certain single terpene-rich botanicals and phenol-rich botanicals were able to modulate oxidative stress, ameliorate epithelial integrity of enterocytes, and support cells to manage ETEC infections in vitro, with specific mechanisms of action and peculiar individual properties (21,22).…”

Combination of fenchone and sodium hyaluronate ameliorated constipation‐predominant irritable bowel syndrome and underlying mechanisms

“…Oral castor oil has a profound effect on colonic motor activity (Karaus et al., 1987). Thyme essential oil maintains epithelial integrity and reduces bacterial translocation (Bonetti et al., 2023). Fenchone (FE), an irregular bicyclic monoterpene ketone, is thought to be derived from rearrangement of a bicyclic precursor.…”