Supplementary Material for: Effects of a protease inhibitor camostat mesilate on gut microbial function in patients with irritable bowel syndrome: A pilot randomized placebo-controlled study

Introduction: Increased fecal protease activity which may induce visceral hypersensitivity has been observed in patients with irritable bowel syndrome (IBS). Serine proteases modulate FK506 binding protein (FKBP)-type peptidylprolyl cis-trans isomerase (PPIase) activity associated with immune and glucocorticoid receptor functions. The aims were to investigate whether camostat mesilate (CM), a serine protease inhibitor, modifies fecal bacterial function associated with FKBP-type PPIases ameliorates in patients with IBS.
Methods: Randomly assigned 16 patients with IBS received 200 mg po tid of CM and 16 patients received placebo for 14 days. Self-reported adequate relief (AR) as a primary endpoint, IBS Symptom Severity Scale (IBS-SSS) and colonic motor and pain thresholds to colorectal distention were assessed before and after treatment. The fecal bacterial content was inferred from 16S rRNA gene sequence data using Phylogenetic Investigation of Communities by Reconstruction of Unobserved States (PICRUSt) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) database.
Results: CM significantly increased the relative abundance of Streptococcus and the functional abundances of serine protease and FKBP-type PPIase FklB and SlyD more than placebo after treatment. CM treatment was not superior to placebo in proportion of AR although colonic motor response partially changed.
Conclusion: CM modulated the fecal microbiome composition and functional potentials that are related to FKBP-type PPIase activity in IBS patients. These findings suggest that protease inhibitors may modify gut microbial function along with abnormal immunological and/or stress responses that underlie pathophysiology of IBS.

引言：在肠易激综合症（IBS）患者中，观察到粪便蛋白酶活性增加，这可能导致内脏高敏感性。丝氨酸蛋白酶调节与免疫和糖皮质激素受体功能相关的FK506结合蛋白（FKBP）型肽基脯氨酰顺反异构酶（PPIase）活性。研究目标在于探究卡莫司他甲酸盐（CM），一种丝氨酸蛋白酶抑制剂，是否能够调节与FKBP型PPIases相关的粪便细菌功能，并改善IBS患者的症状。方法：随机分配16名IBS患者接受200 mg po tid的CM治疗，另16名患者接受安慰剂治疗，持续14天。主要终点为自报的充分缓解（AR），评估IBS症状严重程度量表（IBS-SSS）和结肠运动及痛阈对结肠扩张的反应，在治疗前后进行评估。通过16S rRNA基因序列数据利用系统发育分析通过重建未观察到的状态（PICRUSt）和京都基因与基因组百科全书（KEGG）数据库推断粪便细菌含量。结果：治疗后，CM显著增加了Streptococcus的相对丰度和丝氨酸蛋白酶以及FKBP型PPIase FklB和SlyD的功能丰度，超过安慰剂组。尽管结肠运动反应部分改变，但CM治疗在AR比例上并不优于安慰剂。结论：CM调节了与FKBP型PPIase活性相关的粪便微生物群组成和功能潜力，在IBS患者中显示出其调节作用。这些发现表明，蛋白酶抑制剂可能通过调节肠道微生物功能，伴随异常的免疫和/或压力反应，从而影响IBS的病理生理学。