The impact of gut microbiota changes on the intestinal mucus barrier in burned mice:a study using 16S rRNA and metagenomic sequencing

Background:The gut microbiota is a complex ecosystem that plays a critical role in human health and disease.However,the relationship between gut microbiota and intestinal damage caused by burns is not well understood.The intestinal mucus layer is crucial for maintaining intestinal homeostasis and providing a physiological barrier against bacterial invasion.This study aims to investigate the impact of gut microbiota on the synthesis and degradation of intestinal mucus after burns and explore potential therapeutic targets for burn injury.Methods:A modified histopathological grading system was employed to investigate the effects of burn injury on colon tissue and the intestinal mucus barrier in mice.Subsequently,16S ribosomal RNA sequencing was used to analyze alterations in the gut microbiota at days 1-10 post-burn.Based on this,metagenomic sequencing was conducted on samples collected at days 1,5 and 10 to investigate changes in mucus-related microbiota and explore potential underlying mechanisms.Results:Our findings showed that the mucus barrier was disrupted and that bacterial translocation occurred on day 3 following burn injury in mice.Moreover,the gut microbiota in mice was significantly disrupted from days 1 to 3 following burn injury,but gradually recovered to normal as the disease progressed.Specifically,there was a marked increase in the abundance of symbiotic and pathogenic bacteria associated with mucin degradation on day 1 after burns,but the abundance returned to normal on day 5.Conversely,the abundance of probiotic bacteria associated with mucin synthesis changed in the opposite direction.Further analysis revealed that after a burn injury,bacteria capable of degrading mucus may utilize glycoside hydrolases,flagella and internalins to break down the mucus layer,while bacteria that synthesize mucus may help restore the mucus layer by promoting the production of short-chain fatty acids.Conclusions:Burn injury leads to disruption of colonic mucus barrier and dysbiosis of gut microbiota.Some commensal and pathogenic bacteria may participate in mucin degradation via glycoside hydrolases,flagella,internalins,etc.Probiotics may provide short-chain fatty acids(particularly butyrate)as an energy source for stressed intestinal epithelial cells,promote mucin synthesis and accelerate repair of mucus layer.

Intestinal barrier in inflammatory bowel disease

A complex mucosal barrier protects as the first line of defense the surface of the healthy intestinal tract from adhesion and invasion by luminal microorganisms. In this review, we provide an overview about the major components of this protective system as for example an intact epithelium, the synthesis of various antimicrobial peptides (AMPs) and the formation of the mucus layer. We highlight the crucial importance of their correct functioning for the maintenance of a proper intestinal function and the prevention of dysbiosis and disease. Barrier disturbances including a defective production of AMPs, alterations in thickness or composition of the intestinal mucus layer, alterations of pattern-recognition receptors, defects in the process of autophagy as well as unresolved endoplasmic reticulum stress result in an inadequate host protection and are thought to play a crucial role in the pathogenesis of the inflammatory bowel diseases Crohn’s disease and ulcerative colitis.

Interaction between mucus layer and gut microbiota in non-alcoholic fatty liver disease:Soil and seeds

The intestinal mucus layer is a barrier that separates intestinal contents and epithelial cells,as well as acts as the"mucus layer-soil"for intestinal flora adhesion and colonization.Its structural and functional integrity is crucial to human health.Intestinal mucus is regulated by factors such as diet,living habits,hormones,neurotransmitters,cytokines,and intestinal flora.The mucus layer’s thickness,viscosity,porosity,growth rate,and glycosylation status affect the structure of the gut flora colonized on it.The interaction between"mucus layer-soil"and"gut bacteria-seed"is an important factor leading to the pathogenesis of non-alcoholic fatty liver disease(NAFLD).Probiotics,prebiotics,fecal microbiota transplantation(FMT),and wash microbial transplantation are efficient methods for managing NAFLD,but their long-term efficacy is poor.FMT is focused on achieving the goal of treating diseases by enhancing the"gut bacteria-seed".However,a lack of effective repair and management of the"mucus layer-soil"may be a reason why"seeds"cannot be well colonized and grow in the host gut,as the thinning and destruction of the"mucus layer-soil"is an early symptom of NAFLD.This review summarizes the existing correlation between intestinal mucus and gut microbiota,as well as the pathogenesis of NAFLD,and proposes a new perspective that"mucus layer-soil"restoration combined with"gut bacteria-seed"FMT may be one of the most effective future strategies for enhancing the long-term efficacy of NAFLD treatment.