Enrofloxacin Induces Intestinal Microbiota-Mediated Immunosuppression in Zebrafish

Abstract

The immunosuppressive effects of antibiotics and the potential associations with the intestinal microbiota of the host have been increasingly recognized in recent years. However, the detailed underlying mechanisms of immune interference of antibiotics in environmental organisms remain unclear, particularly at the early life stage of high sensitivity. To better understand the gut microbiome and immune function interactions, the vertebrate model, zebrafish, was treated with environmentally relevant concentrations of a frequently detected antibiotic, enrofloxacin (ENR), ranging from 0.01 to 100 μg/L. 16S ribosomal RNA sequencing indicated diminished diversity, richness, and evenness of intestinal flora following ENR treatment. Twenty-two taxa of gut bacteria including Rickettsiales, Pseudomonadales, and Flavobacteriales were significantly correlated with immunosuppressive biomarkers, including a significant decrease in the abundance of macrophages and neutrophils. To validate the immunomodulatory effects due to altered intestinal microbial populations, zebrafish reared under sterile and non-sterile husbandry conditions were compared after ENR treatment. A significant inhibitory effect was induced by ENR treatment under non-sterile conditions, while the number of macrophages and neutrophils, as well as biomarkers of immunosuppressive effects, were significantly salved in zebrafish under sterile conditions, confirming for the first time that immunosuppression by ENR was closely mediated through alterations of the intestinal microbiome in fish.

Effect of Enrofloxacin on the Microbiome, Metabolome, and Abundance of Antibiotic Resistance Genes in the Chicken Cecum

“…The microbial diversity was higher in the C3 group, treated with a high dose of enrofloxacin, than in the C2 group, treated with a low dose. This is consistent with the results of previous studies ( 19 , 30 ). This may be because high concentrations of enrofloxacin more significantly disrupted the intestinal flora and reduced colonization resistance, favoring an increase in microbial diversity in the early stages of recovery.…”

“…Antibiotics alter the composition and function of the host microbial community ( 18 ). Enrofloxacin-exposed zebrafish show significant differences in bacterial communities and intestinal flora richness ( 19 ). Changes in taxa with high and low abundances in the pig intestinal flora were also observed after the administration of tylosin ( 20 ).…”

Amino Acid Transporter as a Potential Carrier Protein for the Root-to-Shoot Translocation of Polybrominated Diphenyl Ethers in Rice

“…It was observed that the treatment of PBDEs significantly enhanced the expression of the LHT protein throughout the exposure periods, among which BDE-77 promoted LHT the most by 1.66–6.99-fold compared to the control (Figure S7). Next, to validate whether the enhanced LHT expression and PBDE translocation were due to the selective binding of PBDEs with the LHT protein, in vitro fluorescence spectra, CD, and sorption equilibrium experiments were conducted. − …”

Intestinal Permeability, Gut Inflammation, and Gut Immune System Response Are Linked to Aging-Related Changes in Gut Microbiota Composition: A Study in Female Mice

“…They were all negatively correlated with the expression of genes related to immunity. A recent study by Qiu et al ( 40 ) showed a positive correlation between Flavobacteriales and immunosuppressive biomarkers in zebrafish. However, the Flavobacteriaceae family has not been extensively studied, thus more research is necessary to clarify its role.…”