The intestinal microbiota is a crucial regulator of human health and disease because of its interactions with the immune system. Tobacco smoke also influences the human ecosystem with implications for disease development. This systematic review aims to analyze the available evidence, until June 2021, on the relationship between traditional and/or electronic cigarette smoking and intestinal microbiota in healthy human adults. Of the 2645 articles published in PubMed, Scopus, and Web of Science, 13 were included in the review. Despite differences in design, quality, and participants’ characteristics, most of the studies reported a reduction in bacterial species diversity, and decreased variability indices in smokers’ fecal samples. At the phylum or genus level, the results are very mixed on bacterial abundance both in smokers and non-smokers with two exceptions. Prevotella spp. appears significantly increased in smokers and former smokers but not in electronic cigarette users, while Proteobacteria showed a progressive increase in Desulfovibrio with the number of pack-years of cigarette (p = 0.001) and an increase in Alphaproteobacteria (p = 0.04) in current versus never smokers. This attempt to systematically characterize the effects of tobacco smoking on the composition of gut microbiota gives new perspectives on future research in smoking cessation and on a new possible use of probiotics to contrast smoke-related dysbiosis.

Background and Objectives: JAK inhibitors entered current clinical practice as treatment for several immune-related diseases and, recently, for atopic dermatitis. These drugs target the Janus Kinase intracellular cascade, rendering them suitable for treating both Th1 and Th2 immune-mediated responses. Materials and Methods: We report the case of a 36-year-old male patient presenting an overlap of ulcerative colitis, a Th1-related disease, and atopic dermatitis, a Th2-mediated condition. Treatment with upadacitinib was initiated, and laboratory and instrumental follow-ups were carried out for 8 months. Results: The complete and persistent clinical remission of both conditions was observed at a low dose of 15 mg of upadacitinib, even though ulcerative colitis guidelines usually recommend a dosage of 45 mg. No serious adverse responses to therapy were reported. Conclusions: Upadacitinib may be the most suitable management strategy in subjects with coexisting severe conditions mediated by Th1 inflammation, such as ulcerative colitis, and by Th2 cytokines, such as atopic dermatitis.

Background Intestinal microbiota (IM) plays a crucial role in maintaining human body homeostasis, yet it is highly susceptible to lifestyle changes and environmental factors, such as tobacco and e-cig smoking. This systematic review aims to investigate the relationship between smoking and IM in healthy humans, by assessing abundance of Phyla and species' variability. Methods PubMed, Scopus and Web of Science were searched until April 2019. Studies assessing IM of healthy adult tobacco/e-cig smokers, collected on faecal samples and analysed with genome sequencing of rRNA 16 S, were included. Any type of study design, described in English, was considered. Quality assessment was performed with Methodological index for non-randomized studies and Joanna Briggs Institute Critical Appraisal tool for cross-sectional studies. Results Eight out of 1,838 studies (one controlled prospective and seven cross-sectional studies) were included. The only controlled prospective study found a significant increase in α and β-diversity, an increase in Firmicutes (p = 0.014) and a decrease in Bacteroidetes (p = 0.019) after a smoking cessation intervention. In cross- sectional studies, five out of seven studies found a statistically significant decrease in α-diversity among tobacco/e-cig smokers, while results on β-diversity were more contradictory. One out of two studies evaluating Firmicutes found a significant decrease in smokers (p = 0.047). The only study assessing Bacteroidetes found a significant increase among smokers (p = 0.015). Five studies analysed genera, three of them found a decrease in Bacteroides and two an increase in Prevotella. Conclusions What seems to emerge is a decreasing species’ variability in smokers, yet it is difficult to profile IM in smokers in terms of phyla’s abundance, because of few studies available and some further limitations, such as small sample sizes and lack of adjusted analysis to cope with confounding factors like gender, diet and other lifestyles. Key messages There is a decrease in species’ variability among smokers. Further studies are needed to assess abundance of phyla in healthy smokers, taking into account confounding factors.