Gut microbiota is regarded as the second human genome and forgotten organ, which is symbiotic with the human host and cannot live and exist alone. The gut microbiota performs multiple physiological functions and plays a pivotal role in host health and intestinal homeostasis. However, the gut microbiota can always be affected by various factors and among them, it is radiotherapy that results in gut microbiota 12dysbiosis and it is often embodied in a decrease in the abundance and diversity of gut microbiota, an increase in harmful bacteria and a decrease in beneficial bacteria, thereby affecting many disease states, especially intestine diseases. Furthermore, gut microbiota can produce a variety of metabolites, among which short-chain fatty acids (SCFAs) are one of the most abundant and important metabolites. More importantly, SCFAs can be identified as second messengers to promote signal transduction and affect the occurrence and development of diseases. Radiotherapy can lead to the alterations of SCFAs-producing bacteria and cause changes in SCFAs, which is associated with a variety of diseases such as radiation-induced intestinal injury. However, the specific mechanism of its occurrence is not yet clear. Therefore, this review intends to emphasize the alterations of gut microbiota after radiotherapy and highlight the alterations of SCFAs-producing bacteria and SCFAs to explore the mechanisms of radiation-induced intestinal injury from the perspective of gut microbiota and its metabolite SCFAs.

The purpose of this study was to investigate the effects of astragalus polysaccharides (APS) on the proliferation and apoptosis of bone marrow mesenchymal stem cells (BMSCs) induced by X-ray radiation-induced A549 cells bystander effect (RIBE), and to explore their mechanisms. In this study, APS increased the reduced cell proliferation rate induced by RIBE and inhibiting the apoptosis of bystander cells. In terms of mechanism, APS up-regulates the proteins Bcl-2, Bcl-xl, and downregulates the proteins Bax and Bak, which induces a decrease in mitochondrial membrane potential, which induces the release of Cyt-c and AIF, which leads to caspase-dependent and caspaseindependent pathway to cause apoptosis. In addition, we believe that ROS may be the main cause of these protein changes. APS can inhibit the generation of ROS in bystander cells and thus inhibit the activation of the mitochondrial pathway, further preventing cellular damage caused by RIBE.

The gut microbiota is important in metabolism and immune modulation, and compositional disruption of the gut microbiota population is closely associated with inflammation caused by ionizing radiation (IR). Guiqi Baizhu decoction (GQBZD) is a medicinal compound used in traditional Chinese medicine with anti-inflammatory and antioxidation effects, especially in the process of radiotherapy. However, the effect of GQBZD on reducing the damage to the normal immune system in radiotherapy remains unclear. Here, we show that GQBZD reduces body weights, water intake, food intake, diarrhea level and quality of life score, and inflammation and enhances immunity function in rats treated with X-ray radiation. Meanwhile, our data indicate that GQBZD not only reverses IR-induced gut dysbiosis as indicated change of α-diversity and β-diversity of microbiota, the composition of Desulfovibrio, Bacteroides, and Parabacteroides, except for Roseburia and Lachnoclostridium, but also maintains intestinal barrier integrity and promoting the formation of short-chain fatty acids (SCFAs). GQBZD can also reduce the level of phosphorylation P65 (p-P65). Our results demonstrate that GQBZD can significantly alleviate the inflammatory responses and improve the immune damage against IR, and may be used as prebiotic agents to prevent gut dysbiosis and radiation-related metabolic disorders in radiotherapy.

Background: Many pairwise meta-analyses (MAs) related to therapies of varicose veins have been published, but their reporting and methodological quality remain unclear. The present study was designed to assess the overall quality of pairwise MAs related to therapies of varicose veins. Methods: We will systematically search 4 electronic databases, including PubMed, EMBASE, Cochrane Library, Chinese Biomedical Database, to identify pairwise MAs related to therapies of varicose veins. The search time-span was set from inception to March 2019. The pairwise MAs related to therapies of varicose veins will be included in our overview. The reporting and methodological quality of included MAs will be assessed using preferred reporting items for systematic review and meta-analysis and a measurement tool to assess systematic reviews 2, respectively. Meanwhile, we will extract some general characteristics of included MAs, including first author; published year, journal, sample size, number of studies, number of randomized controlled trials and intervention details, and so on. All literatures screening, quality assessment, and data extraction will be independently completed by 2 of all reviewers, and any disagreement will be resolved by discussion. Besides, an increasingly popular method – evidence mapping, will be used to present the whole evidence landscape related to therapies of varicose veins. The assessment results will be presented as percentage and event/total. The Excel 2016 will be used to manage and analyze data. Results: The results of the overview will be submitted to a peer-reviewed journal for publication. Conclusion: This overview will summarize the overall reporting and methodological quality related to therapies of varicose veins. PROSPERO registration number: CRD42019126722.