[Abstract]
Crohn’s disease is a chronic disorder that typically affects the gastrointestinal tract. The increased incidence in the recent years, especially in Asian countries, prompts for performing studies and gain newer insights into the etiology and pathogenesis of the disease. Among other causative factors, gut microbiome and its cross-talk with the salivary microbiome is a known factor that has a plausible role in the pathogenesis of Crohn’s disease. The gut microbiome has been extensively studied, however, the salivary microbiome and its dynamics during different phases of this disease remain understudied. In this study, we obtained saliva samples from the patients during active and remission phases of the disease and compared them with control samples and highlighted the differences in taxonomic as well as predicted functional pathways among them. Our results indicated that the α and β diversities were signifificantly lower during the active phase in contrast with remission phase and healthy samples. In general, Firmicutes were most abundant among the three sample groups, followed by Bacteroidetes and Proteobacteria. Genus level distribution highlighted Streptococcus, Neisseria, Prevotella, Haemophilus, and Veillonella as the five most abundant taxa. Differential abundance analysis of the three sample groups identifified signifificant enrichment of 30 bacterial taxa in the active phase that included g_Prevotella, f_Prevotellaceae, and p_Bacteroidetes. Furthermore, remission phase and control also exhibited signifificant enrichment of 24 and 22 bacterial taxa, respectively. Eleven differentially abundant pathways were also identifified, four were signifificantly enriched in healthy controls whereas other seven were signifificantly enriched in active phase of the disease. Several important pathways, such as ribosome biogenesis and Energy metabolism were depleted in the active phase. Our study has highlighted several taxa and functional categories that could be implicated with the onset of Crohn’s disease and thus have the potential to serve as biomarkers of the active disease. However, these findings require further validation through functional studies in the future.
【中文摘要】
克羅恩病（CD）是一種慢性腸道炎症性疾病。近年來，CD發病率逐年增加，許多研究聚焦於其病因和發病機制有了部分新的發現。其中，腸道菌群和口腔菌群的相互作用被認為在CD的發病機制中有著重要作用。CD患者的腸道菌群已經被廣泛研究，但其口腔菌群特徵以及不同臨床分期的變化尚未被揭示。在本研究中，我們收集活動期及緩解期CD患者的唾液樣本進行16sRNA測序，並將其與健康對照人群的唾液樣本的菌群特徵進行對比，揭示其在菌群分類及預測功能方面的差異。我們的研究發現，與緩解期CD患者及健康人群相比，活動期CD患者口腔菌群的α多態性及β多態性均有明顯的降低。總體來說，三組樣品中最豐富的為厚壁菌門，其次為類桿菌門及蛋白質菌門。屬級分布顯示鏈球菌屬、奈瑟菌屬、普雷沃菌屬、嗜血桿菌屬及韋榮菌屬為最豐富的分類群。三組樣本的差異豐度分析顯示活動期CD患者唾液中30個細菌類群（包括前卵藻、前角藻科和類桿菌）具有明顯富集。此外，緩解期CD患者及健康對照組也分別表現出24和22個細菌類群有顯著富集。11條差異豐度通路中，健康對照組有4條，活動期CD患者組有7條。活動期患者中，諸如核糖體生物合成和能量代謝等一些重要的通路缺失。我們的研究發現口腔菌群的分類和功能可能與CD的發病相關，患者口腔菌群的特徵可能成為疾病活動性的生物標誌物，這些發現需要未來的功能學研究加以證實。