Mixed Eimeria infections disrupt tight junctions and microbial homeostasis to compromise the intestinal mucosal barrier in rabbits: partial protection by Lactiplantibacillus plantarum supplementation

Mixed Eimeria infections were examined for their synergistic effects on the physical, chemical, and biological components of the rabbit intestinal mucosal immune system. species from clinical cases were identified morphologically and by PCR, and an experimental infection model was established. Intestinal pathology was evaluated by H & E staining; cytokines, immunoglobulins, and tight-junction proteins were measured by ELISA and qPCR; and gut microbiota were profiled by 16 S rRNA sequencing. Five species—Eimeria flavescens, Eimeria intestinalis, Eimeria magna, Eimeria vejdovskyi, and Eimeria perforans—were confirmed. Infection caused villus atrophy and collapse in the small intestine with a reduced villus height/crypt depth (VH/CD) ratio. Tight-junction proteins (Occludin, Claudins, ZO-1) were downregulated, indicating severe physical barrier damage. Mucin-2 (MUC2) increased in the duodenum and jejunum but decreased in the colon during gametogony. Microbial α-diversity increased, the Bacteroidota/Bacillota ratio fell, beneficial genera (e.g., Akkermansia, Lachnospiraceae) declined, and pro-inflammatory Clostridia_UCG-014 expanded. Serum IgA decreased, intestinal sIgA responses were region-specific, and IL-6 and TNF-α were elevated and associated with subsequent microbial shifts. Finally, Lactiplantibacillus plantarum supplementation partially restored mucosal architecture, enhanced Occludin and MUC2 expression, reduced TNF-α and MDA levels, and normalized the microbial community, highlighting its potential as a supportive intervention. Mixed Eimeria infections disrupt tight-junction integrity, alter mucin metabolism, and induce profound microbial dysbiosis, collectively compromising intestinal barrier structure and mucosal function. Supplementation with Lactiplantibacillus plantarum partially restored these impairments by improving epithelial sealing, enhancing mucin production, and rebalancing the gut microbiota.