Homeostasis of the Intestinal Mucosa in Healthy Horses-Correlation between the Fecal Microbiome, Secretory Immunoglobulin A and Fecal Egg Count

Agnieszka Żak-Bochenek; Joanna Bajzert; Dominika Sambor; Natalia Siwińska; Bogumiła Szponar; Łukasz Łaczmański; Paulina Żebrowska; Aleksandra Czajkowska; Maciej Karczewski; Anna Chełmońska-Soyta

doi:10.3390/ani12223094

Homeostasis of the Intestinal Mucosa in Healthy Horses-Correlation between the Fecal Microbiome, Secretory Immunoglobulin A and Fecal Egg Count

Animals (Basel). 2022 Nov 10;12(22):3094. doi: 10.3390/ani12223094.

Affiliations

¹ Department of Immunology, Pathophysiology and Veterinary Preventive Medicine, Faculty of Veterinary Medicine, Wrocław University of Environmental and Life Sciences, C. Norwida 31, 50-375 Wroclaw, Poland.
² Department of Internal Diseases and Clinic of Diseases of Horses, Dogs and Cats, Faculty of Veterinary Medicine, Wrocław University of Environmental and Life Sciences, C. Norwida 31, 50-375 Wroclaw, Poland.
³ Laboratory of Genomics and Bioinformatics, Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, 53-114 Wroclaw, Poland.
⁴ Department of Applied Mathematics, Faculty of Environmental Engineering and Geodesy, Wrocław University of Environmental and Life Sciences, C. Norwida 31, 50-375 Wroclaw, Poland.

Abstract

The defensive function of the intestinal mucosa depends both on the ability to secrete immunoglobulin A and communication with the mucus microbiome. In horses, the functioning of this system is also influenced by the presence of nematode eggs. Feces collected from healthy horses were examined to determine the fecal egg count, immunoglobulin A level (ELISA), microbiome composition (Next-Generation Sequencing, NGS, V3−V4 and V7−V9 hypervariable regions of the 16S rRNA gene analysis and short-chain fatty acid (SCFA) production ((high-performance liquid chromatography, HPLC). In the taxonomic analysis within the phylum, the following order of dominance was found: Firmicutes, Bacteroidota, Verrucomicrobiota and Fibrobacterota. The coefficient of phylogenetic diversity of the microbiome positively correlated with both secretory immunoglobulin A (SIgA) [μg/g of feces] (p = 0.0354, r = 0.61) and SIgA [μg/mg of fecal protein] (p = 0.0382, r = 0.6) and with the number of Cyathostomum eggs (p = 0.0023, r = 0.79). Important components of the key microbiome in horses, such as phylum Proteobacteria and species Ruminococcus flavefaciens, were positively correlated with the fecal SIgA (p < 0.05). All the obtained results indicate the existence of significant relationships between the host response (SIgA production) and composition and SCFA production in the microbiome as well as the presence of small strongyles in the digestive tract of horses.

Keywords: Cyathostomum; gastrointestinal tract; mucosal immunity; secretory immunoglobulin A; short-chain fatty acids.

Grants and funding

The research was financed under the following projects: “Study of the secretory role of Immunoglobulin A in regulating immune responses in the digestive tract in healthy horses and horses with inflammatory bowel disease (CIBD)”. Innovative Scientist, 2020-21, N060 /0021/20 and “Characteristics of the intestinal microbiome in individual parts of the digestive tract in healthy horses and horses with inflammatory bowel disease”. NCN Miniatura 4, 2020/04 /X /NZ6 /02146; the APC/BPC is financed/co-financed by Wroclaw University of Environmental and Life Sciences.