STUDIO DEL RUOLO DEI FATTORI AMBIENTALI NELL’EZIOPATOGENESI DELLA DISBIOSI ASSOCIATA A DISTURBI CRONICI INTESTINALI.

Background: Growing evidence supports the potential role of environmental factors, such as diet and lifestyle, in modulating the intestinal microbiota, possibly influencing the onset or the maintenance of symptoms in Chronic Gastrointestinal Disorders. The present study aimed to correlate lifestyle habits with the colonic microbiota composition in patients with Inflammatory Bowel Disease (IBD) or Irritable Bowel Syndrome (IBS) compared to healthy controls (HC). Materials and methods: 18 IBD, 33 IBS and 26 healthy control subjects were recruited from the Gastroenterology Unit of the Fondazione Campus Bio-medico Hospital. Fecal microbiota was analyzed by sequencing the 16s rDNA, v3/v4 region on the Illumina platform. Eating habits and the amount of physical activity were detected by a 7-day food diary, the Food Frequency Questionnaire (FFQ) and IPAQ questionnaires. Data obtained from next-generation sequencing was analyzed using QIIME software; the Shannon and Pielou indexes were used for alpha diversity while UniFrac weighted and unweighted were performed for beta diversity. microRNA, as biomarker of internal exposome related to inflammation and oxidative stress, were analysed by TaqMan technology in Real Time quantitative PCR. Results A significant reduction of dietary fiber consumption was detected in IBD and IBS patients compared to HC (p<0.05). IBS patients performed more moderate physical activity than HC (p< 0.05). Furthermore, weekend IBD patients spent fewer hours sitting than healthy controls (p<0.0005). IBD patients showed a lower Faith diversity index and Observed OTUs diversity index than HC (p= 0.025 and p= 0.02 respectively). Moreover, the Faith index showed an increased diversity in subjects living in a rural context compared to subjects of urban environment. Reduced fiber consumption was correlated with a reduction in microbial diversity (p<0.005) compared to an adequate fiber intake. In IBDs, a significant reduction of Verrucomicrobiota was observed, compared to IBSs and HCs. Instead, in IBS patients an increase of Firmicutes and Proteobacteriota and a reduction of Bacteroidota and Verrucomicrobiota was observed compared to healthy controls. The LEfSe analysis (Linear discriminant analysis Effect Size) and ANCOM analysis (Analysis of composition of microbiomes) identified Ruminococcus bromii significantly associated with the HCs. In contrast, Lawsonibacter asaccharolyticus and C. massiliensis were associated by ANCOM analysis with IBD and IBS patients respectively. Regarding the mean in subjects not adhering to the Mediterranean diet, the t-test showed that IBD patients had a significantly higher mean than controls (p=0.0206) and then IBS patients (p=0.004). Conclusions The preliminary results of the present study underlined the influence of lifestyle habits, such as diet, in modulating intestinal microbial diversity. A larger cohort of patients is mandatory to confirm this evidence.