Background and Aims:
Mesenteric lymph nodes are sites in which translocated bacteria incite and
progress immunological responses. For this reason, understanding the microbiome of mesenteric
lymph nodes in inflammatory bowel disease is important. The bacterial profile of Crohn’s disease
mesenteric lymph nodes has been analysed using culture-independent methods in only one
previous study. This study aimed to investigate the mesenteric lymph node microbiota from both
Crohn’s disease and ulcerative colitis patients.
Methods: Mesenteric lymph nodes were collected from Crohn’s disease and ulcerative colitis
patients undergoing resection. Total DNA was extracted from mesenteric lymph nodes and
assessed for the presence of bacterial DNA [16S]. All work was completed in a sterile environment
using aseptic techniques. Samples positive for 16S DNA underwent next-generation sequencing,
and the identity of bacterial phyla and species were determined.
Results: Crohn’s disease mesenteric lymph nodes had a distinctly different microbial profile to
that observed in ulcerative colitis. The relative abundance of Firmicutes was greater in nodes from
ulcerative colitis patients, whereas Proteobacteria were more abundant in Crohn’s disease. Although
species diversity was reduced in the mesenteric lymph nodes of patients with Crohn’s disease,
these lymph nodes contained greater numbers of less dominant phyla, mainly Fusobacteria.
Conclusion: This study confirms that there are distinct differences between the Crohn’s disease
and ulcerative colitis mesenteric lymph node microbiomes. Such microbial differences could aid in
the diagnosis of Crohn’s disease or ulcerative colitis, particularly in cases of indeterminate colitis at
time of resection, or help explain their mechanisms of development and progression.