The novel coronavirus severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of coronavirus disease 2019 (COVID-19) and the ensuing worldwide pandemic. The spread of the virus has had global effects such as activity restriction, economic stagnation, and collapse of healthcare infrastructure. Severe SARS-CoV-2 infection induces a cytokine storm, leading to acute respiratory distress syndrome (ARDS) and multiple organ failure, which are very serious health conditions and must be mitigated or resolved as soon as possible. Mesenchymal stem cells (MSCs) and their exosomes can affect immune cells by inducing anti-inflammatory macrophages, regulatory T and B cells, and regulatory dendritic cells, and can inactivate T cells. Hence, they are potential candidate agents for treatment of severe cases of COVID-19. In this review, we report the background of severe cases of COVID-19, basic aspects and mechanisms of action of MSCs and their exosomes, and discuss basic and clinical studies based on MSCs and exosomes for influenza-induced ARDS. Finally, we report the potential of MSC and exosome therapy in severe cases of COVID-19 in recently initiated or planned clinical trials of MSCs (33 trials) and exosomes (1 trial) registered in 13 countries on ClinicalTrials.gov.

PURPOSE: The activities of breast cancer resistance protein (Bcrp/ABCG2) as well as P-glycoprotein (P-gp) and drug-metabolizing enzymes can be inhibited by several flavonoids or drugs in rats. However, the species, gender and regional differences of effects of flavonoids on Bcrp/ABCG2 in rats and mice remain unclear, although Bcrp, like P-gp, is also important in controlling drug absorption and disposition. METHODS: We used chrysin as a model flavonoid because it possesses anti-inflammatory and antioxidative properties and is used as a dietary supplement. We examined the pharmacokinetics of nitrofurantoin, a specific Bcrp substrate, in rats and mice treated with chrysin. Bcrp mRNA levels were measured in liver, kidney, duodenum, jejunum and ileum in rats and mice. RESULTS: Plasma concentrations of nitrofurantoin were increased in rats, but not mice, treated with oral chrysin, compared with untreated controls. Intraperitoneal injection of chrysin into rats or mice had little effect on the elimination of nitrofurantoin, compared with untreated animals. CONCLUSIONS: These results suggest that chrysin-nitrofurantoin interactions occur in the small intestine in rats, but not in mice, possibly due to the higher levels of Bcrp expression in the small intestine in rats, compared with those in mice.

The liver has a high regenerative ability and can induce spontaneous regression of fibrosis when early liver damage occurs; however, these abilities are lost when chronic liver damage results in decompensated cirrhosis. Cell therapies, such as mesenchymal stem cell (MSC) and macrophage therapies, have attracted attention as potential strategies for mitigating liver fibrosis. Here, we evaluated the therapeutic effects of HMGB1 peptide synthesized from box A of high mobility group box 1 protein. Liver damage and fibrosis were evaluated using a carbon tetrachloride (CCl4)-induced cirrhosis mouse model. The effects of HMGB1 peptide against immune cells were evaluated by single-cell RNA-seq using liver tissues, and those against monocytes/macrophages were further evaluated by in vitro analyses. Administration of HMGB1 peptide did not elicit a rapid response within 36 h, but attenuated liver damage after 1 week and suppressed fibrosis after 2 weeks. Fibrosis regression developed over time, despite continuous liver damage, suggesting that administration of this peptide could induce fibrolysis. In vitro analyses could not confirm a direct effect of HMGB1 peptide against monocyte/macrophages. However, macrophages were the most affected immune cells in the liver, and the number of scar-associated macrophages (Trem2+Cd9+ cells) with anti-inflammatory markers increased in the liver following HMGB1 treatment, suggesting that indirect effects of monocytes/macrophages were important for therapeutic efficacy. Overall, we established a new concept for cell-free therapy using HMGB1 peptide for cirrhosis through the induction of anti-inflammatory macrophages.

Ulcerative colitis, a chronic and recurrent inflammatory disease, is localized to the colonic mucosa but can affect other organs and lead to various complications. Gastroduodenitis associated with ulcerative colitis has been reported. However, little is known about esophageal ulcers. We herein report two rare cases of esophageal ulcers associated with ulcerative colitis. Furthermore, the clinical and histological characteristics of 18 previously reported cases are summarized. This case series and literature review will encourage the accurate diagnosis and treatment of esophageal ulcers associated with ulcerative colitis.

Background and Aims: Decompensated cirrhosis with fibrosis progression causes portal hypertension followed by an oedematous intestinal tract. These conditions weaken the barrier function against bacteria in the intestinal tract, a condition called leaky gut, resulting in invasion by bacteria and bacterial components. Here, we investigated the role of outer-membrane vesicles (OMVs) of Escherichia coli, which is the representative pathogenic gut-derived bacteria in patients with cirrhosis in the pathogenesis of cirrhosis. Methods:We investigated the involvement of OMVs in humans using human serum and ascites samples and also investigated the involvement of OMVs from E. coli in mice using mouse liver-derived cells and a mouse cirrhosis model.