Kiely Christopher J, Pavli Paul, O'Brien Claire L
IBD Research Laboratory, Medical School, College of Medicine, Biology and Environment, Australian National University, Canberra, Capital of Australia, Australia.
Gastroenterology and Hepatology Unit, Canberra Hospital, Canberra, Australian Capital Territory, Australia.
Intern Med J. 2018 Nov;48(11):1346-1354. doi: 10.1111/imj.13998.
Using culture-based methods, bacterial translocation from the gut to draining mesenteric lymph nodes is seen in 5% of normal controls and up to 33% of patients with inflammatory bowel diseases (IBD). Many bacteria cannot be cultured, so these methods are unable to capture the full spectrum of bacteria present.
To detect viable bacteria in lymph nodes of patients with IBD and non-IBD controls using bacterial RNA as a surrogate for viability and to compare them with the same patient's gut microbiome.
Bacterial RNA was extracted from lymph nodes and mucosa of 20 patients who had undergone intestinal resection (10 IBD, 10 non-IBD). A previous study had detected bacterial DNA in these patients' lymph nodes; 16S rRNA gene high-throughput sequencing was performed.
Bacterial RNA was detected in the lymph nodes of five patients with IBD and three controls (volvulus, diverticulitis and bowel obstruction). Lymph nodes had higher alpha (within sample) diversity compared to mucosal samples (Shannon diversity index 2.41 vs 1.81, one-way ANOVA P = 0.035). Beta diversity (inter-sample variation: lymph node vs intestine) was similar within individuals and did not differ between groups. Common gene polymorphisms linked with IBD (NOD2, ATG16L1, IRGM and IL23R) were not associated with bacterial translocation.
Metabolically active bacteria mirroring the individual's gut microbiome were commonly found in the lymph nodes of patients with IBD undergoing resection. An increase in lymph node alpha diversity is likely due to the larger drainage area. The presence of viable bacteria in non-IBD controls is also not unexpected given the underlying pathology in these patients.
采用基于培养的方法时，在5%的正常对照以及高达33%的炎症性肠病（IBD）患者中可观察到细菌从肠道向引流的肠系膜淋巴结发生移位。许多细菌无法培养，因此这些方法无法全面检测出存在的细菌种类。
以细菌RNA作为活力替代指标，检测IBD患者和非IBD对照者淋巴结中的活菌，并将其与同一患者的肠道微生物群进行比较。
从20例接受肠道切除术的患者（10例IBD患者，10例非IBD患者）的淋巴结和黏膜中提取细菌RNA。之前的一项研究已在这些患者的淋巴结中检测到细菌DNA；进行了16S rRNA基因高通量测序。
在5例IBD患者和3例对照者（肠扭转、憩室炎和肠梗阻患者）的淋巴结中检测到细菌RNA。与黏膜样本相比，淋巴结的α（样本内）多样性更高（香农多样性指数分别为2.41和1.81，单因素方差分析P = 0.035）。个体内部的β多样性（样本间变异：淋巴结与肠道）相似，且组间无差异。与IBD相关的常见基因多态性（NOD2、ATG16L1、IRGM和IL23R）与细菌移位无关。
在接受切除术的IBD患者的淋巴结中普遍发现了反映个体肠道微生物群的代谢活跃细菌。淋巴结α多样性增加可能是由于引流区域更大。鉴于这些非IBD对照患者的潜在病理状况，在其淋巴结中存在活菌也并不意外。
