Gut microbiome on immune checkpoint inhibitor therapy and consequent immune-related colitis: a review

Immune checkpoint inhibitors have dramatically revolutionized the therapeutic landscape for patients with advanced malignancies. Recently, convincing evidence has shown meaningful influence of gut microbiome on human immune system. With the complex link between gut microbiome, host immunity and cancer, the variations in the gut microbiota may influence the efficacy of immune checkpoint inhibitors. Indeed, some bacterial species have been reported to be predictive for cancer outcome in patients treated with immune checkpoint inhibitors. Although immune checkpoint inhibitors are currently proven to be an effective anti-tumor treatment, they can induce a distinct form of toxicity, termed immune-related adverse events. Immune-related colitis is one of the common toxicities from immune checkpoint inhibitors, and it might preclude the cancer therapy in severe or refractory cases. The manipulation of gut microbiome by fecal microbiota transplantation or probiotics administration has been suggested as one of the methods to enhance anti-tumor effects and decrease the risk of immune-related colitis. Here we review the role of gut microbiome on immune checkpoint inhibitor therapy and consequent immune-related colitis to provide a new insight for better anti-cancer therapy.

Recent progress in mucosal immunology and vaccine development

No abstract available.

Mucosal dendritic cells shape mucosal immunity

Dendritic cells (DCs) are key modulators that shape the immune system. In mucosal tissues, DCs act as surveillance systems to sense infection and also function as professional antigen-presenting cells that stimulate the differentiation of naive T and B cells. On the basis of their molecular expression, DCs can be divided into several subsets with unique functions. In this review, we focus on intestinal DC subsets and their function in bridging the innate signaling and adaptive immune systems to maintain the homeostasis of the intestinal immune environment. We also review the current strategies for manipulating mucosal DCs for the development of efficient mucosal vaccines to protect against infectious diseases.

Shigella flexneri Inhibits Intestinal Inflammation by Modulation of Host Sphingosine-1-Phosphate in Mice

Infection with invasive Shigella species results in intestinal inflammation in humans but no symptoms in adult mice. To investigate why adult mice are resistant to invasive shigellae, 6~8-week-old mice were infected orally with S. flexneri 5a. Shigellae successfully colonized the small and large intestines. Mild cell death was seen but no inflammation. The infected bacteria were cleared 24 hours later. Microarray analysis of infected intestinal tissue showed that several genes that are involved with the sphingosine-1-phosphate (S1P) signaling pathway, a lipid mediator which mediates immune responses, were altered significantly. Shigella infection of a human intestinal cell line modulated host S1P-related genes to reduce S1P levels. In addition, co-administration of S1P with shigellae could induce inflammatory responses in the gut. Here we propose that Shigella species have evasion mechanisms that dampen host inflammatory responses by lowering host S1P levels in the gut of adult mice.

Ginsan Enhances Humoral Antibody Response to Orally Delivered Antigen

BACKGROUND: There have been several reports describing the capability of ginseng extracts as an adjuvant. In this study, we tested if ginsan, a polysaccharide extracted from Panax ginseng, was effective in enhancing antibody response to orally delivered Salmonella antigen. METHODS: Ginsan was treated before oral salmonella antigen administration. Salmonella specific antibody was determined by ELISA. mRNA expression was determined by RT-PCR. Cell migration was determined by confocal microscopy and flow cytometry. COX expression was detected by western blot. RESULTS: Ginsan treatment before oral Salmonella antigen delivery significantly increased both secretory and serum antibody production. Ginsan increased the expression of COX in the Peyer's patches. Various genes were screened and we found that CCL3 mRNA expression was increased in the Peyer's patch. Ginsan increased dendritic cells in the Peyer's patch and newly migrated dendritic cells were mostly found in the subepithelial dome region. When COX inhibitors were treated, the expression of CCL3 was reduced. COX inhibitor also antagonized both the migration of dendritic cells and the humoral immune response against oral Salmonella antigen. CONCLUSION: Ginsan effectively enhances the humoral immune response to orally delivered antigen, mediated by CCL3 via COX. Ginsan may serve as a potent vaccine suppliment for oral immunization.