Probiotic Combination CBLEB Alleviates Infection Through Immune Regulation in Immunocompromised Rats.

BACKGROUND

() is the most common cause of bacterial pneumonia, especially for people with immature or compromised immune systems. In addition to vaccination and antibiotics, immune regulation through microbial intervention has emerged in recent anti- infection research. This study investigated the therapeutic effect of a combination of live , and (CBLEB), a widely used probiotic drug, on infection in rats.

METHODS

An immunocompromised -infection rat model was established by intraperitoneal injection of cyclophosphamide and nasal administration of strain ATCC49619. Samples from -infected, -infected and CBLEB-treated, and healthy rats were collected to determine blood indicators, serum cytokines, gut microbiota, faecal and serum metabolomes, lung- and colon-gene transcriptions, and histopathological features.

RESULTS

CBLEB treatment alleviated weight loss, inflammation, organ damage, increase in basophil percentage, red cell distribution width, and RANTES levels and decrease in total protein and albumin levels of immunocompromised -infection rats. Furthermore, CBLEB treatment alleviated dysbiosis in gut microbiota, including altered microbial composition and the aberrant abundance of opportunistic pathogenic bacterial taxa such as , and disorders in gut and serum metabolism, including altered metabolomic profiles and differentially enriched metabolites such as 2,4-di-tert-butylphenol in faeces and L-tyrosine in serum. The transcriptome analysis results indicated that the underlying mechanism by which CBLEB fights infection is mainly attributed to its regulation of immune-related pathways such as TLR and NLR signalling in the lungs and infection-, inflammation- or metabolism-related pathways such as TCR signalling in the colon.

CONCLUSION

The present study shows a potential value of CBLEB in the treatment of infection.