Microbiome diversity declines while distinct expansions of Th17, iNKT, and dendritic cell subpopulations emerge after anastomosis surgery

Abstract

Background Anastomotic failure causes morbidity and mortality even in technically correct anastomoses. Initial leaks must be prevented by mucosal reapproximation across the anastomosis. Healing is a concerted effort between intestinal epithelial cells (IECs), immune cells, and commensal bacteria. IEC TLR4 activation and signaling is required for mucosal healing, leading to inflammatory factor release that recruits immune cells to limit bacteria invasion. TLR4 absence leads to mucosal damage from loss in epithelial proliferation, attenuated inflammatory response, and bacteria translocation. We hypothesize after anastomosis, an imbalance in microbiota will occur due to a decrease in TLR4 expression and will lead to changes in the immune milieu. Results We isolated fecal content and small intestinal leukocytes from murine, Roux-en-Y and end-to-end anastomoses, to identify microbiome changes and subsequent alterations in the regulatory and pro-inflammatory immune cells 3 days post-operative. TLR4+ IECs were impaired after anastomosis. Microbiome diversity was reduced, with Firmicutes, Bacteroidetes, and Saccharibacteria decreased and Proteobacteria increased. A distinct TCRβhi CD4+ T cells subset after anastomosis was 10–20-fold greater than in control mice. 84% were Th17 IL-17A/F+ IL-22+ and/or TNFα+. iNKT cells were increased and TCRβhi. 75% were iNKT IL-10+ and 13% iNKTh17 IL-22+. Additionally, Treg IL-10+ and IL-22+ cells were increased. A novel dendritic cell subset was identified in anastomotic regions that was CD11bhi CD103mid and was 93% IL-10+. Conclusions This anastomotic study demonstrated a decrease in IEC TLR4 expression and microbiome diversity which then coincided with increased expansion of regulatory and pro-inflammatory immune cells and cytokines. Defining the anastomotic mucosal environment could help inform innovative therapeutics to target excessive pro-inflammatory invasion and microbiome imbalance.

Microbiota Phenotype Promotes Anastomotic Leakage in a Model of Rats with Ischemic Colon Resection

“…These results are in line with what was previously described, where low diversity has been observed in the microbiota of the anastomotic tissue that develops AL [ 27 , 28 , 29 ]. This may be so because reduced diversity may be associated with an increase in undesirable microbiota and a decrease in beneficial microbiota, resulting in compromised intestinal resistance [ 30 ].…”

Changes in HLA-B27 Transgenic Rat Fecal Microbiota Following Tofacitinib Treatment and Ileocecal Resection Surgery: Implications for Crohn’s Disease Management

“…It should be noted that these procedures and, notably, those with caecum suppression, were obviously linked to intestinal insufficiency. It is well known that anatomical reconstructions lead to changes in the physiological function and composition of gut microbiota, including ICR and small bowel SBR, as well as other intestinal surgeries, such as Roux-en-Y gastric bypass procedures [56][57][58]. All may promote a loss of diversity and the deep modification of the microbiota associated with pro-inflammatory events.…”

Clarifying the effect of gut microbiota on allergic conjunctivitis risk is instrumental for predictive, preventive, and personalized medicine: a Mendelian randomization analysis

“…Changes in Firmicutes and Bacteroidetes are particularly significant in many pathological states since these two constitute the vast majority of the bacterial population. Trans-differentiation of Th17 cells into regulatory T cells (Tregs) is connected with the ratio of Firmicutes to Bacteroidetes, which could be used as a disease predictor [ 58 ]. Our investigation revealed that the genera Ruminococcaceae_UCG_002 , Holdemanella, Catenibacterium , and Oscillospira , all of the phylum Firmicutes, are associated with the onset of allergic conjunctivitis.…”