Cytokines may be crucially involved in the pathogenesis of inflammatory bowel diseases (IBD), but it remains controversial whether interferon (IFN)-γ, a typical proinflammatory cytokine, is an essential mediator to cause the disorders. In the present study, IFN-γ^–/– and wild-type (WT) C57BL/6 mice were fed 2·5% dextran sodium sulphate (DSS) in drinking water for 7 days, in order to investigate DSS-induced intestinal inflammation. The DSS-treated WT mice exhibited a robust production of IFN-γ in the gut, a remarkable loss of body weight, as well as high rate of mortality (60%). In striking contrast, IFN-γ deficient mice did not develop DSS-induced colitis, as indicated by the maintenance of body weight and survival rate of 100%. Severe intestinal inflammation was demonstrated exclusively in WT animals in terms of the shortening of the bowel as well as the elevation of the disease activity index, myeloperoxidase (MPO) activity and serum haptoglobin level. Histological study of DSS-treated WT intestine revealed disruption of mucosal epithelium and massive infiltration of inflammatory cells, while the organ from IFN-γ^–/– mice remained virtually normal in appearance. Enzyme-linked immunosorbent assay (ELISA) analyses indicated abundant production of three chemokines, i.e. monokine induced by interferon-γ (MIG), interferon-inducible protein 10 (IP-10) and monocyte chemoattractant protein-1 (MCP-1), in the DSS-irritated intestine of WT but not of IFN-γ^–/– mice. The present results demonstrate clearly that IFN-γ plays indispensable roles in the initiation of DSS colitis, and some chemokines are produced in an IFN-γ-dependent fashion.

SARS-CoV-2 has mutated during the global pandemic leading to viral adaptation to medications and vaccinations. Here we describe an engineered human virus receptor, ACE2, by mutagenesis and screening for binding to the receptor binding domain (RBD). Three cycles of random mutagenesis and cell sorting achieved sub-nanomolar affinity to RBD. Our structural data show that the enhanced affinity comes from better hydrophobic packing and hydrogen-bonding geometry at the interface. Additional disulfide mutations caused the fixing of a closed ACE2 conformation to avoid off-target effects of protease activity, and also improved structural stability. Our engineered ACE2 neutralized SARS-CoV-2 at a 100-fold lower concentration than wild type; we also report that no escape mutants emerged in the co-incubation after 15 passages. Therapeutic administration of engineered ACE2 protected hamsters from SARS-CoV-2 infection, decreased lung virus titers and pathology. Our results provide evidence of a therapeutic potential of engineered ACE2.

Significance: Osteoblasts produce bone matrix and contribute to bone remodeling. We have established a procedure to directly convert human fibroblasts into osteoblasts by transducing some defined factors and culturing in osteogenic medium. Osteoblast-specific transcription factors, Runx2 and Osterix, in combination with Oct4 and L-Myc, drastically induced fibroblasts to produce calcified bone matrix and express osteoblast-specific markers. The directly converted osteoblasts (dOBs) showed similar gene expression profiles as normal osteoblasts and contributed to bone repair after transplantation into mice with bone defects. Furthermore, dOBs did not require continuous expression of the exogenous genes to maintain their phenotype. These findings strongly suggest successful direct reprogramming of fibroblasts into osteoblasts, which may be applicable to bone regeneration therapy.

Potential effects of tea and its constituents on SARS-CoV-2 infection were assessed in vitro. Infectivity of SARS-CoV-2 was decreased to 1/100 to undetectable levels after a treatment with black tea, green tea, roasted green tea, or oolong tea for 1 min. An addition of (−) epigallocatechin gallate (EGCG) significantly inactivated SARS-CoV-2, while the same concentration of theasinensin A (TSA) and galloylated theaflavins including theaflavin 3,3′-di-O-gallate (TFDG) had more remarkable anti-viral activities. EGCG, TSA, and TFDG at 1 mM, 40 µM, and 60 µM, respectively, which are comparable to the concentrations of these compounds in tea beverages, significantly reduced infectivity of the virus, viral RNA replication in cells, and secondary virus production from the cells. EGCG, TSA, and TFDG significantly inhibited interaction between recombinant ACE2 and RBD of S protein. These results suggest potential usefulness of tea in prevention of person-to-person transmission of the novel coronavirus.

RNAi enables potent and specific gene silencing, potentially offering useful means for treatment of cancers. However, safe and efficient drug delivery systems (DDS) that are appropriate for intra‐tumor delivery of siRNA or shRNA have rarely been established, hindering clinical application of RNAi technology to cancer therapy. We have devised hydrogel polymer nanoparticles, or nanogel, and shown its validity as a novel DDS for various molecules. Here we examined the potential of self‐assembled nanogel of cholesterol‐bearing cycloamylose with spermine group (CH‐CA‐Spe) to deliver vascular endothelial growth factor (VEGF)‐specific short interfering RNA (siVEGF) into tumor cells. The siVEGF/nanogel complex was engulfed by renal cell carcinoma (RCC) cells through the endocytotic pathway, resulting in efficient knockdown of VEGF. Intra‐tumor injections of the complex significantly suppressed neovascularization and growth of RCC in mice. The treatment also inhibited induction of myeloid‐derived suppressor cells, while it decreased interleukin‐17A production. Therefore, the CH‐CA‐Spe nanogel may be a feasible DDS for intra‐tumor delivery of therapeutic siRNA. The results also suggest that local suppression of VEGF may have a positive impact on systemic immune responses against malignancies.