Gut microbiome mediated macrophage alterations in the intestine of IBD patients.

Abstract

Intestinal dysbiosis and a dysregulated immune system has been well recognized in the aetiology of inflammatory bowel disease (IBD). However, mechanisms and pathways in-volved remain elusive. Accumulating evidence suggests that bacterial metabolites might greatly impact the immune regulation of the intestine. Butyrate, a short chain fatty ac-ids (SCFA), which is metabolized by the gut bacteria from otherwise indigestible fibre-rich diets, has been shown to ameliorate IBD symptoms. Although the exact mechanisms remain partly understood, it is known that a major drop in butyrate-producing bacteria is associated with the increased pro-inflammatory environment. The increased amount of inflammatory cues facilitate macrophages to differentiate into a pro-inflammatory phenotype. Hence, enhancing butyrate levels in therapy could be a potential treatment for IBD. This review summarised the current knowledge on how butyrate affects intesti-nal macrophages, in terms of recruitment and phenotype polarization. With the inci-dence of IBD outpacing death and global gains in life expectancy, newly diagnosed IBD patients' cases are being added to the pool of prevalent individuals on a continuous ba-sis. Therefore, broadening our knowledge about different pathways is essential for indi-vidualized treatment planning and improving the quality of life of IBD patients.