Coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has rapidly spread across the world. Inactivating the virus in saliva and the oral cavity represents a reasonable approach to prevent human-to-human transmission because the virus is easily transmitted through oral routes by dispersed saliva. Persimmon-derived tannin is a condensed type of tannin that has strong antioxidant and antimicrobial activity. In this study, we investigated the antiviral effects of persimmon-derived tannin against SARS-CoV-2 in both in vitro and in vivo models. We found that persimmon-derived tannin suppressed SARS-CoV-2 titers measured by plaque assay in vitro in a dose- and time-dependent manner. We then created a Syrian hamster model by inoculating SARS-CoV-2 into hamsters’ mouths. Oral administration of persimmon-derived tannin dissolved in carboxymethyl cellulose before virus inoculation dramatically reduced the severity of pneumonia with lower virus titers compared with a control group inoculated with carboxymethyl cellulose alone. In addition, pre-administration of tannin to uninfected hamsters reduced hamster-to-hamster transmission of SARS-CoV-2 from a cohoused, infected donor cage mate. These data suggest that oral administration of persimmon-derived tannin may help reduce the severity of SARS-CoV-2 infection and transmission of the virus.

Nontuberculous mycobacteria (NTM), including Mycobacterium avium complex (MAC), cause opportunistic chronic pulmonary infections. Notably, MAC susceptibility is regulated by various factors, including the host immune system. Persimmon (Ebenaceae Diospyros kaki Thunb.) tannin is a condensed tannin composed of a polymer of catechin groups. It is well known that condensed tannins have high antioxidant activity and bacteriostatic properties. However, it is hypothesized that condensed tannins might need to be digested and/or fermented into smaller molecules in vivo prior to being absorbed into the body to perform beneficial functions. In this study, we evaluated the effects of soluble persimmon-derived tannins on opportunistic MAC disease. Soluble tannins were hydrolyzed and evaluated by the oxygen radical absorbance capacity (ORAC) method. The ORAC value of soluble tannin hydrolysate was approximately five times greater than that of soluble tannin powder. In addition, soluble tannin hydrolysate exhibited high bacteriostatic activity against MAC in vitro. Furthermore, in an in vivo study, MAC infected mice fed a soluble tannin-containing diet showed significantly higher anti-bacterial activity against MAC and less pulmonary granuloma formation compared with those fed a control diet. Tumor necrosis factor α and inducible nitric oxide synthase levels were significantly lower in lungs of the soluble tannin diet group compared with the control diet group. Moreover, proinflammatory cytokines induced by MAC stimulation of bone marrow-derived macrophages were significantly decreased by addition of soluble tannin hydrolysate. These data suggest that soluble tannin from persimmons might attenuate the pathogenesis of pulmonary NTM infection.

Single-cell RNA-sequencing (scRNA-seq) is valuable for analyzing cellular heterogeneity. Cell composition accuracy is critical for analyzing cell–cell interaction networks from scRNA-seq data. However, droplet- and plate-based scRNA-seq techniques have cell sampling bias that could affect the cell composition of scRNA-seq datasets. Here we developed terminator-assisted solid-phase cDNA amplification and sequencing (TAS-Seq) for scRNA-seq based on a terminator, terminal transferase, and nanowell/bead-based scRNA-seq platform. TAS-Seq showed high tolerance to variations in the terminal transferase reaction, which complicate the handling of existing terminal transferase-based scRNA-seq methods. In murine and human lung samples, TAS-Seq yielded scRNA-seq data that were highly correlated with flow-cytometric data, showing higher gene-detection sensitivity and more robust detection of important cell–cell interactions and expression of growth factors/interleukins in cell subsets than 10X Chromium v2 and Smart-seq2. Expanding TAS-Seq application will improve understanding and atlas construction of lung biology at the single-cell level.

Ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD) induced by dysregulation of the immune response in the intestinal mucosa. Although the underlying mechanisms of UC development are not fully understood, disruption of gut microbiota, “dysbiosis”, is thought to lead to the development of IBD. Persimmon (Ebenaceae Diospyros kaki Thunb.)-derived tannin, which is a condensed polymeric tannin consisting of catechin groups, has antioxidant, anti-inflammatory, and antimicrobial activities. In this study, we assessed the effect of persimmon-derived tannin on a murine model of UC established by dextran sulfate sodium-induced colitis in female mice. Dietary supplementation of tannin significantly decreased disease activity and colon inflammation. A hydrolysate of tannin directly suppressed expression of inflammatory genes in macrophages in vitro. In faecal microbiota, the relative abundance of Bacteroides was increased significantly by tannin supplementation. Alpha-diversity indices in colitis-induced mice were significantly higher in the tannin diet group compared with the control diet group. Additionally, expansion of Enterobacteriaceae and Enterococcus, which is associated with disease progression of IBD, was remarkably suppressed in the tannin diet group. These results suggest that persimmon-derived tannin ameliorates colon inflammation in UC through alteration of the microbiota composition and immune response, which may be a promising candidate for IBD therapy.

Bifidobacterium breve M-16V is a probiotic bacterial strain with efficacy in infants achieved by suppressing T-helper type (Th) 2 immune responses and modulating the systemic Th1/ Th2 balance. Exposure to air pollution during pregnancy increases asthma susceptibility in offspring. The aim of this study was to investigate the effects of the maternal intake of B. breve M-16V on susceptibility to asthma accelerated by prenatal exposure to air pollution. The intake of B. breve M-16V in residual oil fly ash (ROFA)-exposed pregnant mice resulted in fewer eosinophils in the bronchoalveolar lavage fluid of neonatal mice and reduced allergic lung inflammation. The expressions of Th2 cytokines including IL-5 and IL-13 were decreased in neonatal mice from ROFA-exposed mothers fed B. breve M-16V. The analysis of fecal microbiota from neonatal mice revealed that the intake of B. breve M-16V by mothers changed the composition of fecal microbiota in neonatal mice, which resulted in a decreased population of Firmicutes. Moreover, several bacterial strains of fecal microbiota from neonatal mice had a strong correlation with Th2 cytokines and histological score. These results suggest that the maternal intake of M-16V might have beneficial effects in neonates by preventing and/or alleviating allergic reactions accelerated by prenatal exposure to air pollution.