Understanding the pathophysiology of anastomic leakage
The prevalence of anastomotic leakage (AL) after colorectal surgery is between 10 – 15% in the Netherlands. Its pathophysiology remains poorly understood and current options to prevent it are limited. However, Konstantina Zafeiropoulou’s PhD research indicates that preoperative abundance of Prevotella associates with anastomotic healing. Looking at AL from a preventative angle is unique, timely, and should lead to reduced mortality, morbidity, and associated medical costs.
Figure 1. Preoperative abundance of Prevotella associates with AH after colorectal surgery in the absence of profound preoperative AL-related fecal microbial dysbiosis. Source.
(A) Alpha diversity indices (i.e., Richness, Shannon, Simpson diversity) and local contribution to beta diversity (LBCD) of preoperative fecal samples (rarefied to 30,000 reads) from patients who underwent colorectal surgery (n = 57); (B) Nonmetric multidimensional scaling plots of the fecal beta diversity based on unweighted UniFrac distance (upper panel) and Bray-Curtis dissimilarity index (lower panel); (C) Log2fold changes of the 16 discriminatory between AL and AH patients genera (P (adjusted) < 0.05, see also Table S2 and Figure S2); asterisk indicates Bioenv-selected taxa suggested as major determinants of the community complexity (see also Table S1); stripes indicate influential taxa based on the conventional random forest classification-feature importance analysis; taxa essential components of the Prevotella enterotype are indicated with dark green (same color as Prevotella enterotype in panel (D)); the red dashed arrows highlight the significant absence of Prevotella-related taxa in AL; (D) Relative contribution of the three enterotypes in the AL and AH patients.
Single-cell research into epithelial and immune cells
Following her initial study into preoperative AL-related microbiome in 2021, Zafeiropoulou is now working on data from a second cohort. The Gut Research PhD candidate, who is a diet specialist, is analyzing data from a multi-center Dutch REVEAL cohort (>400). The cohort is overseen by Joep Derikx, pediatric surgeon at Emma Hospital, part of Amsterdam UMC. To discover more about the anastomosis, Zafeiropoulou will be using mass cytometry to observe Prevotella’s effect on the colon’s epithelial and immune cells at single-cell level in an animal model.
Can we reverse the AL phenotype?
In the next step, an established animal model with the AL phenotype will be colonized with Prevotella to investigate whether the bacteria can reverse the phenotype. And whether temporarily feeding the mice a high-fiber diet is sufficient, or if a diet combined with a probiotic is more effective.
Next-generation sequencing analysis
The initial study analyzed patients’ related samples using two high-throughput next-generation sequencing analysis approaches, including anastomotic tissue-associated bulk RNA sequencing and preoperative fecal 16S rRNA gene sequencing. It found that in the absence of host epithelial gene expression differences, the preoperative fecal microbiota of patients who heal from colorectal resection differs from the group of patients who develop AL in the abundance of Prevotella and suggested a potential beneficial role of Prevotella that may prove useful as a predictive biomarker for AH.
See you at DDW in May 22
Zafeiropoulou will be speaking on the findings during a plenary session of #DigestiveDiseaseWeek in San Diego this May. Full publication will follow once the animal model research has been completed (expected in 2023). Read the preprint of the initial study here.