Mayo, B. | bioRxiv Science

bioRxiv2025

Irinotecan-induced mucositis is associated with variation in the expression of regulatory compounds associated with goblet cells

Alimentary mucositis (AM) is a common side effect of antineoplastic treatment and a key reason for cessation of treatment, compromising the chance of remission. Gastrointestinal mucin secretion is associated with regulatory compounds nitric oxide and its respective synthases inducible, epithelial and neural nitric oxide synthase (iNOS, eNOS and nNOS, respectively), vasoactive intestinal polypeptide (VIP), and prostaglandin E2 (PGE2). Changes in secretion during mucositis have been demonstrated in numerous studies, however no secretory regulatory signals have been associated in mucositis induced secretory change. The aim of this study is to investigate regulator factors in the gastrointestinal tract involved in mucin secretion, VIP, NOS, and PGE2, which are suspected of being involved in mucositis, specifically through alteration of neural or goblet cells. Tumour-bearing Dark Agouti rats received a single dose of 175 mg/kg of irinotecan (i.p.) and 0.01mg/kg atropine. (s.c.). Rats were killed post treatment at 6, 24, 48, 72, 96 and 120 hours. Samples were collected, immunohistochemistry and real time PCR were performed to analyse the expression of iNOS, eNOS, nNOS, VIP, and PGE2. Following irinotecan treatment, staining intensity for iNOS positive goblet cells in the crypts of the jejunum decreased significantly at 48 h (p < 0.05). VIP, and PGE2 positive goblet cell numbers showed no change. mRNA expression in iNOS, eNOS, and nNOS showed no change. Irinotecan-induced mucositis is associated with altered secretory regulatory compounds; this may affect mucin secretion increasing the severity of irinotecan induced mucositis.

pharmacology and toxicology↗

bioRxiv2017

Demonstration of de novo chemotaxis in E. coli using a real-time, quantitative, and digital-like approach

Chemotaxis is the movement of an organism in response to an external chemical stimulus. This system enables bacteria to sense their immediate environment and adapt to changes in its chemical composition. Bacterial chemotaxis is mediated by chemoreceptors, membrane proteins that bind an effector and transduce the signal to the downstream proteins. From a synthetic biology perspective, the natural chemotactic repertoire is of little use since bacterial chemoreceptors have evolved to sense specific ligands that either benefit or harm the cell. Here we demonstrate that using a combined computational design approach together with a quantitative, real-time, and digital detection approach, we can rapidly design, manufacture, and characterize a synthetic chemoreceptor in E. coli for histamine (a ligand for which there are no known chemoreceptors). First, we employed a computational protocol that uses the Rosetta bioinformatics software together with high threshold filters to design mutational variants to the native Tar ligand binding domain that target histamine. Second, we tested different ligand-chemoreceptors pairs with a novel chemotaxis assay, based on optical reflectance interferometry of porous silicon (PSi) optical transducers, enabling label-free quantification of chemotaxis by monitoring real-time changes in the optical readout (expressed as the effective optical thickness, EOT). We found that different ligands can be characterized by an individual set of fingerprints in our assay. Namely, a binary, digital-like response in EOT change (i.e. positive or negative) that differentiates between attractants and repellants, the amplitude of change of EOT response, and the rate by which steady state in EOT change is reached. Using this assay, we were able to positively identify and characterize a single mutational chemoreceptor variant for histamine that mediated chemotaxis comparably to the natural Tar-aspartate system. Our results demonstrate the possibility of not only expanding the natural chemotaxis repertoire, but also provide a new quantitative assay by which to characterize the efficacy of the chemotactic response.

synthetic biology↗