Inflammatory bowel diseases (IBD) are currently considered multifactorial pathologies in which various combined environmental factors act on a genetic background, giving rise to a chronic inflammation of the gastrointestinal tract. Among the various environmental factors, it now seems clear that the diet plays the major role in IBD onset and progression. Several clinical studies have attempted to understand the impact of diet in the development and progression of these diseases in order to establish useful guidelines for their management. However, the modest and sometimes contradictory results did not lead to the definition of shared dietary suggestions. On the other hand, food fads and recommendations based on anecdotal episodes are often followed by IBD patients to improve their diet. This review provides a critical overview of existing data on the role of diet as a risk factor for IBD. The methodology used was that of analyzing the results of clinical studies conducted on diet and IBD over the last 12 years through PubMed, as well as analyzing the most relevant studies on nutrients and their possible roles in IBD through the knowledge of the mechanisms by which they can modulate the microbiota or the intestinal physiology.

Background: COVID-19, whose causative pathogen is the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), was declared a pandemic in March 2020. The gastrointestinal tract is one of the targets of this virus, and mounting evidence suggests that gastrointestinal symptoms may contribute to disease severity. The gut–lung axis is involved in the immune response to SARS-CoV-2; therefore, we investigated whether COVID-19 patients’ bacterial and fungal gut microbiome composition was linked to disease clinical outcome.Methods: In May 2020, we collected stool samples and patient records from 24 hospitalized patients with laboratory-confirmed SARS-CoV-2 infection. Fungal and bacterial gut microbiome was characterized by amplicon sequencing on the MiSeq, Illumina’s integrated next generation sequencing instrument. A cohort of 201 age- and sex-matched healthy volunteers from the project PRJNA661289 was used as a control group for the bacterial gut microbiota analysis.Results: We observed that female COVID-19 patients had a lower gut bacterial microbiota richness than male patients, which was consistent with a different latency in hospital admittance time between the two groups. Both sexes in the COVID-19 patient study group displayed multiple positive associations with opportunistic bacterial pathogens such as Enterococcus, Streptococcus, and Actinomyces. Of note, the Candida genus dominated the gut mycobiota of COVID-19 patients, and adult patients showed a higher intestinal fungal diversity than elderly patients. We found that Saccharomycetales unassigned fungal genera were positively associated with bacterial short-chain fatty acid (SCFA) producers and negatively associated with the proinflammatory genus Bilophila in COVID-19 patients, and we observed that none of the patients who harbored it were admitted to the high-intensity unit.Conclusions: COVID-19 was associated with opportunistic bacterial pathogens, and Candida was the dominant fungal taxon in the intestine. Together, we found an association between commensal SCFA-producers and a fungal genus that was present in the intestines of patients who did not experience the most severe outcome of the disease. We believe that this taxon could have played a role in the disease outcome, and that further studies should be conducted to understand the role of fungi in gastrointestinal and health protection.

Patients with surgical Crohn’s colitis (CC) might either undergo a total colectomy (TC) and ileo-rectal anastomosis (IRA), or TC and end ileostomy. Among the latter group, a second-stage IRA is not always performed. The predictors of the different outcomes after TC (including the recurrence of disease at the level of the anastomosis) are yet to be identified. Retrospective study including 354 patients undergoing TC for CC (2000–2019), with a minimum preoperative follow-up of 2 years in our centre. The mean postoperative follow-up was 67.5+/-49.8 months (62 patients lost). The primary end-points were to identify the predictors for the following outcomes: a) IRA (87 cases, 24.6%) vs. end ileostomy (267 cases, 75.4%) at the primary colectomy. b) second-stage IRA (80 cases, 39%) vs. no IRA (125 cases, 61%) at the last follow-up. c) recurrence of the disease after IRA (167 patients). Considering the large number of regressors and the risk of over-fitting, the least absolute shrinkage and selection operator (LASSO) method was used. A multivariate analysis was carried out using the preselected covariates. The analysis was conducted using logistic regression and cox regression for dichotomus and time-dependent outcomes. A p-value<0.05 was considered significant. a) Predictors against the IRA at primary TC: preoperative biologic exposure (OR=1.96, CI 1.15–3.33, p=0.014), Crohn’s rectal location (OR=4.17, CI 2.0–8.33, p<0.0001), perianal disease (OR=3.33, CI 1.75–6.25, p<0.0001), and low hemoglobin concentration (OR=1.26, CI 1.01–1.58, p=0.037). b) Predictors of the risk of still having the ileostomy at the follow-up: age (OR: 1.02, CI 1.00–1.04, p=0.045), exposure to biologics before (OR 1.85, CI 1.11–3.03, p=0.017) and after (OR 1.79, CI 1.11–2.89, p=0.018) the TC; postoperative use of azathioprine was associated with a greater chance of a second-stage IRA (OR 2.66, CI 1.21–5.83, p=0.014). c) Risk of anastomotic recurrence was 8.7% and 30.8% at 5 and 10 years. Significant predictors were: female gender (OR 2.38, CI 1.11–5.55, p=0.046), use of more than one biologic (OR 5.65, CI 2.18–9.89, p<0.0001) and worsening of symptoms needing for drug escalation (OR 5.51, CI 2.06–8.59, p=0.001) during the follow-up. The location and severity of the disease at diagnosis predict the long-term behavior of the disease. The exposure to biologics, especially if multiple drugs are required, does not represent a risk for worse outcomes per se, but rather identifies a population at higher risk of permanent ileostomy due to more severe disease. These predictors might be implemented in the assessment of patients affected by CC, in order to identify the population at risk of permanent ileostomy.

Mirikizumab is a selective anti-IL-23 monoclonal antibody approved for moderate-to-severe ulcerative colitis (UC). Evidence regarding its efficacy mostly derives from registration trials, as real-world data in multi-refractory populations remain limited. We conducted an observational study including UC patients treated with mirikizumab. Clinical activity was assessed using the partial Mayo (pMayo) score at baseline, Week12 (W12), and Week24 (W24). Urgency, biomarkers, endoscopic activity and safety were evaluated. Steroid-free clinical remission (SFCR) was defined as pMayo≤1 without corticosteroids; clinical response as ≥3-point or ≥30% reduction. Changes over time were analyzed using paired non-parametric tests; logistic regression identified predictors of remission. One-hundred-twenty-three highly treatment-expierenced patients were included (median 3 prior advanced therapies, IQR 2-4). Most patients (89.0%) continued extended IV induction after W12. SFCR was achieved in 25.2% (31/123) at W12 and 31.3% (30/96) at W24, while clinical response occurred in 70.7% and 67.7%, respectively. Bowel urgency improved at W12 and W24 (p<0.001). Adverse events occurred in 20.3% of patients; the colectomy rate was 4.9%. Higher baseline pMayo and prior JAKi exposure were associated with lower remission. Mirikizumab showed encouraging effectiveness and safety in multirefractory UC. Prior JAKi exposure emerged as a potential negative predictor of remission; this hypothesis-generating signal warrants validation.