Oncological Surgery Unit, Veneto Institute of Oncology (IOV-IRCCS), via Gattamelata 64, 35128, Padua, Italy.
J Gastrointest Surg. 2012 Jan;16(1):188-201; discussion 201-2. doi: 10.1007/s11605-011-1720-6. Epub 2011 Oct 8.
Defensins are small cationic peptides with antibacterial activity expressed in Paneth cells (α-defensins) or generally in intestinal epithelial cells (β-defensins) that have a profound effect on gut microbiota. Chronic pouchitis, which occurs in 5% of patients after restorative proctocolectomy and can cause pouch failure, is associated to a significant increase of Clostridiaceae spp. The aim of this study was to gain further insight in the pathogenesis of pouch dysbiosis by exploring defensin expression. Thirty-two consecutive patients coming for follow-up endoscopy were recruited. On pouch biopsies, we cultured bacteria adherent to the mucosa and determined α- and β-defensins and toll-like receptor-4 and -2 mRNA by quantitative real-time RT-PCR. Serum and mucosal levels of IL-1β, IL-6 and TNF-α were measured with immunometric assays. Faecal lactoferrin was analysed by quantitative ELISA. After a median follow-up of 23 (IQR 20-24) months, the patients were contacted for a reassessment of current and past disease activity. During the follow-up, chronic/relapsing pouchitis was diagnosed in six patients. The mucosal level of α-5 and α-6 defensins correlated with chronic/relapsing pouchitis onset (τ = 0.30, p = 0.034 and τ = 0.28, p = 0.053, respectively). High levels of α-5 defensin resulted to be predictive of chronic/relapsing pouchitis [AUC = 74% (95% CI = 53-89%), p = 0.052]. Patients with high levels of α-5 and α-6 defensins had earlier pouchitis relapses (p = 0.009 and p = 0.034, respectively). High levels of α-5 defensin were associated to a significant risk of chronic/relapsing pouchitis [OR = 10.6 (95% CI = 1.2-97.6), p = 0.027]. At multivariate analysis, the mucosal levels of α-5 defensin and the number of CFU of mucosa-associated Clostridiaceae spp resulted to be independent predictors of chronic/relapsing pouchitis [β = 0.46 (0.18), p = 0.024 and β = 0.44 (0.18), p = 0.027, respectively]. In conclusion, chronic/relapsing pouchitis is associated to increased expression of mucosal HD-5 and to increased antimicrobial activity against Escherichia coli. In patients with chronic/relapsing pouchitis, HD-5 and TLR-4 over-expression is likely to create a hostile environment against Enterobacteriaceae, thus favouring Clostridiaceae spp by decreasing competing bacteria families.
防御素是一种具有抗菌活性的阳离子小肽，在潘氏细胞（α-防御素）或一般在肠上皮细胞（β-防御素）中表达，对肠道微生物群有深远影响。直肠储袋炎发生在修复性直肠结肠切除术后的 5%的患者中，可导致储袋功能障碍，与梭菌科 spp 的显著增加有关。本研究旨在通过探索防御素表达，进一步了解储袋功能障碍的发病机制。招募了 32 例连续接受随访内镜检查的患者。在储袋活检中，我们培养了黏附在黏膜上的细菌，并通过实时定量 RT-PCR 测定了 α-和 β-防御素以及 Toll 样受体 4 和 2 的 mRNA。用免疫比浊法测定血清和黏膜中 IL-1β、IL-6 和 TNF-α的水平。用定量 ELISA 分析粪便乳铁蛋白。在中位数为 23（IQR 20-24）个月的随访后，联系患者以评估当前和过去的疾病活动。在随访期间，6 名患者被诊断为慢性/复发性直肠储袋炎。黏膜 α-5 和 α-6 防御素水平与慢性/复发性直肠储袋炎的发生相关（τ=0.30，p=0.034 和 τ=0.28，p=0.053）。高水平的 α-5 防御素可预测慢性/复发性直肠储袋炎[AUC=74%（95%CI=53-89%），p=0.052]。高水平 α-5 和 α-6 防御素的患者直肠储袋炎复发较早（p=0.009 和 p=0.034）。高水平的 α-5 防御素与慢性/复发性直肠储袋炎的显著风险相关[OR=10.6（95%CI=1.2-97.6），p=0.027]。在多变量分析中，黏膜 α-5 防御素水平和黏膜相关梭菌科 spp 的 CFU 数量是慢性/复发性直肠储袋炎的独立预测因子[β=0.46（0.18），p=0.024 和 β=0.44（0.18），p=0.027]。总之，慢性/复发性直肠储袋炎与黏膜 HD-5 表达增加以及针对大肠杆菌的抗菌活性增强有关。在慢性/复发性直肠储袋炎患者中，HD-5 和 TLR-4 的过度表达可能会对肠杆菌科产生敌对环境，从而通过减少竞争细菌家族来促进梭菌科 spp 的生长。
