A conserved ion channel function of STING mediates noncanonical autophagy and cell death.

The cGAS/STING pathway triggers inflammation upon diverse cellular stresses such as infection, cellular damage, aging, and diseases. STING also triggers noncanonical autophagy, involving LC3 lipidation on STING vesicles through the V-ATPase-ATG16L1 axis, as well as induces cell death. Although the proton pump V-ATPase senses organelle deacidification in other contexts, it is unclear how STING activates V-ATPase for noncanonical autophagy. Here we report a conserved channel function of STING in proton efflux and vesicle deacidification. STING activation induces an electron-sparse pore in its transmembrane domain, which mediates proton flux in vitro and the deacidification of post-Golgi STING vesicles in cells. A chemical ligand of STING, C53, which binds to and blocks its channel, strongly inhibits STING-mediated proton flux in vitro. C53 fully blocks STING trafficking from the ER to the Golgi, but adding C53 after STING arrives at the Golgi allows for selective inhibition of STING-dependent vesicle deacidification, LC3 lipidation, and cell death, without affecting trafficking. The discovery of STING as a channel opens new opportunities for selective targeting of canonical and noncanonical STING functions.

Exosomes from CD133+ human urine-derived stem cells combined adhesive hydrogel facilitate rotator cuff healing by mediating bone marrow mesenchymal stem cells.

Background: The inadequate regeneration of natural tissue (mainly fibrocartilage) between tendon and bone during rotator cuff (RC) repair results in an unsatisfactory quality of RC healing. Cell-free therapy based on stem cell exosomes is a safer and more promising approach for tissue regeneration. Here, we investigated the effect of exosomes from human urine-derived stem cells (USCs) and their subpopulations (CD133+USCs) on RC healing. Methods: USCs were isolated from urine and sorted by flow cytometry to obtain CD133+ urine-derived stem cells (CD133+ USCs). Urine-derived stem cell exosomes (USC-Exos) and CD133+ urine-derived stem cell exosomes (CD133+ USC-Exos) were subsequently isolated from the cell supernatant and identified by transmission electron microscopy (TEM), particle size analysis, and Western blot. We performed in vitro functional assays to evaluate the effects of USC-Exos and CD133+ USC-Exos on human bone marrow mesenchymal stem cells (BMSCs) proliferation, migration, osteogenic differentiation, and chondrogenic differentiation. In vivo experiments were performed by local injection of exosome-hydrogel complexes for the treatment of RC injury. The effects of CD133+ USC-Exos and USC-Exos on RC healing were assessed from imaging, histological, and biomechanical tests. Results: CD133+ USCs were positive for CD29, CD44, CD73, CD90, CD133, but negative for CD34 and CD45. Differentiation ability test results showed that both USCs and CD133+ USCs had the potential for osteogenic, chondrogenic, and adipogenic differentiation, but CD133+ USCs had stronger chondrogenic differentiation ability. CD133+ USC-Exos and USC-Exos could be efficiently taken up by BMSCs and promote their migration, osteogenic and chondrogenic differentiation. However, CD133+ USC-Exos could promote the chondrogenic differentiation of BMSCs more than USC-Exos. Compared with USC-Exos, CD133+ USC-Exos could promote the healing of bone-tendon interface (BTI) more effectively, which might be related to its ability to promote the differentiation of BMSCs into chondroblasts. Although the two exosomes exhibited the same effect in promoting subchondral bone repair in BTI, the CD133+ USC-Exos group had higher histological scores and stronger biomechanical properties. Conclusion: CD133+ USC-Exos hydrogel complex may become a promising therapeutic approach for RC healing based on stem cell exosomes. The translational potential of this article: This is the first study to assess the specific role of CD133+ USC-Exos in RC healing which may be related to the activation of BMSCs by CD133+ USC-Exos towards chondrogenic differentiation. Further, our study provides a reference for possible future treatment of BTI by applying CD133+ USC-Exos hydrogel complex.

Analysis of the Efficacy and Safety of PEGylated Interferon-α2b Treatment in Inactive Hepatitis B Surface Antigen Carriers.

INTRODUCTION: Hepatitis B virus (HBV) infection is associated with the onset of several major liver diseases. Inactive hepatitis B surface antigen (HBsAg) carriers (IHCs) may be successfully treated with PEGylated interferon-α2b (PEG-IFNα2b)-based antiviral therapy; however, studies on this treatment have been insufficient. In this study, we evaluated the efficacy and safety of PEG-IFNα2b treatment in IHCs. METHODS: Nineteen IHCs were treated with subcutaneous PEG-IFNα2b (180 µg/week) for 48 weeks (treatment group). Patients were followed up for 24 weeks after treatment discontinuation. Twenty untreated control patients were observed for 72 weeks (control group). HBsAg clearance (HBsAg < 0.05 IU/mL), HBsAg seroconversion, and alanine aminotransferase levels were monitored. RESULTS: Of the 19 patients treated with PEG-IFNα2b, 16 showed HBsAg loss (84.2%), and 13 showed HBsAg seroconversion (68.4%) at 72 weeks. All patients in the treatment group exhibited virological response (serum HBV DNA level < 10 IU/mL) at the time of drug withdrawal. In the control group, no patients experienced HBsAg loss during the observational period. There were no serious adverse events during treatment, and the therapy was well tolerated. CONCLUSIONS: Short PEG-IFNα2b therapy in IHCs produced a high functional cure rate and good safety profile, suggesting that PEG-IFNα2b treatment may be the best choice for clinical cure of some IHCs.