Effect of probiotics on the maintenance of intestinal homeostasis after chemotherapy: systematic review and meta-analysis of pre-clinical studies.

Gastrointestinal mucositis (GIM) is an inflammation caused by antitumor therapy, especially after chemotherapy and radiotherapy. Currently in the clinical practice, only palliative measures are taken to treat GIM, representing the main clinical limitation in the management of this condition. Several studies have highlighted the potential benefits of probiotics for the management of GIM, but the actual role of these microorganisms in the maintenance of intestinal homeostasis remains elusive. In this context, here we aimed to realise a systematic review with meta-analysis to evaluate the effect of probiotics on experimental GIM. The meta-analysis showed that probiotics significantly suppressed the body weight loss related to GIM in rodents (95% confidence interval (CI): -2.67 to -0.70; I=98%, <0.00). Subgroup analysis showed that pre-treatment (≥7 days before chemotherapy) (95% CI: -8.84 to -0.17; I=98%, <0.04) with a high dose of probiotics (≥ 10 cfu/day) (95% CI: -2.58 to -0.28; I=98%, <0.00) comprising two or more microorganism species (95% CI: -6.49 to -0.28; I=96%, =0.03) remedied GIM more effectively. It was also revealed that fungi (specifically ) are more effective in remedying GIM than bacteria (=0.03 vs <0.00), and the mouse models are more receptive than rats to the enteroprotective effects of probiotics (95% CI: -4.76, -0.69; I=97%, =0.01). Qualitative analyses highlighted that probiotics suppress GIM through several mechanisms; they reduce the intestinal permeability, suppress the pro-inflammatory cytokine production while stimulating production and secretion of anti-inflammatory cytokines, inhibit the signalling pathways coupled to inflammation and apoptosis, accelerate the proliferation of enterocytes, reduce the levels of reactive oxygen species, and help maintain the protective mucus layer. In conclusion, this review highlights the therapeutic benefits of probiotics in experimental GIM.