Reserpine improves Enterobacteriaceae resistance in chicken intestine via neuro-immunometabolic signaling and MEK1/2 activation

Authors: REDWEIK, GRAHAM - Iowa State University; Kogut, Michael - Mike; ARSENAULT, RYAN - University Of Delaware; LYTE, MARK - Iowa State University; MELLATA, MELHA - Iowa State University

Submitted to: Communications Biology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/10/2021
Publication Date: 12/3/2021
Citation: Redweik, G.A., Kogut, M.H., Arsenault, R.J., Lyte, M., Mellata, M. 2021. Reserpine improves Enterobacteriaceae resistance in chicken intestine via neuro-immunometabolic signaling and MEK1/2 activation. Communications Biology. 4. Article 1359. https://doi.org/10.1038/s42003-021-02888-3.
DOI: https://doi.org/10.1038/s42003-021-02888-3

Interpretive Summary: Chicks get infected with Salmonella bacteria early in life, and the bacteria can survive in the chicks throughout their life by avoiding the chick’s immune system. Our research attempts to discover ways to improve the chick’s immune system so that pathogens like Salmonella will not be able to survive in the chick’s gut. One of the ways that we are interested in improving the chick’s immune system is by increasing the release of special chemicals in the chick’s gut that will stimulate immunity. These chemicals are produced by special cells in the gut called neural cells and when enough are produced, they stimulate immunity. It appears that the Salmonella may prevent the release of these chemicals so that they can live in the chick’s gut. In this experiment, we found that treating the chicks with a drug causes the release of the good chemicals which stimulate immunity and reduce the Salmonella bugs in the intestine. These experiments are important to the poultry industry because they may lead to new methods of preventing these bugs from infecting the chicks.

Technical Abstract: Non-typhoidal Salmonella enterica serovars cause severe illnesses in humans, and poultry is the main environmental reservoir for these bacteria. Due to intestinal immunotolerance induced by Salmonella and increasing antimicrobial resistance, novel means of eradicating Salmonella from poultry are required. To explore the role of the neuroimmunological axis in intestinal Salmonella resistance, we treated chicken ceca tissues with or without 1 µM reserpine, a drug that releases intracellular catecholamine stores. Following reserpine incubation, culture media supernatant was evaluated for neurochemicals and Salmonella resistance via U-HPLC and in vitro bactericidal assays, respectively. Lymphocytes from ceca tissues were similarly treated with or without 1 µM reserpine to determine potential catecholamine sources. To confirm in vivo responses, day-old chickens were orally treated with 0, 0.5, or 5 mg reserpine/kg body weight and orally challenged with Salmonella. Explants were further evaluated for changes in gene expression and kinase activity via RT-qPCR and kinome peptide array, respectively. Reserpine-treated explant media and regulatory T cells had higher norepinephrine release versus untreated controls. Similarly, Salmonella killing was greater in reserpine-treated explants versus controls, and this antimicrobial response was consistent in vivo. Reserpine increased antimicrobial peptide and IL-2 gene expression while reducing CTLA-4 expression. Globally, reserpine induced drastic changes in immunometabolism, inhibiting epidermal growth factor receptor (EGFR) and mammalian target for rapamycin (mTOR) signaling. To assess role of neurochemical release in reserpine-induced antimicrobial responses, norepinephrine treatment alone increased Salmonella resistance, which was blocked using beta-adrenergic receptor inhibitors. To assess the role of immunometabolic signaling changes, EGF treatment reversed reserpine-induced antimicrobial responses, whereas mTOR inhibition via rapamycin increased antimicrobial activities. Finally, we established that MEK1/2 activation plays a central role in reserpine-induced antimicrobial responses via both norepinephrine and mTOR-mediated pathways.