Yang Qiu

The increasing emergence and re-emergence of RNA virus outbreaks underlines the urgent need to develop effective antivirals. RNA interference (RNAi) is a sequence-specific gene silencing mechanism that is triggered by small interfering RNAs (siRNAs) or short hairpin RNAs (shRNAs), which exhibits significant promise for antiviral therapy. AGO2-dependent shRNA (agshRNA) generates a single-stranded guide RNA and presents significant advantages over traditional siRNA and shRNA. In this study, we applied a logistic regression algorithm to a previously published chemically siRNA efficacy dataset and built a machine learning-based model with high predictive power. Using this model, we designed siRNA sequences targeting diverse RNA viruses, including human enterovirus A71 (EV71), Zika virus (ZIKV), dengue virus 2 (DENV2), mouse hepatitis virus (MHV) and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and transformed them into agshRNAs. We validated the performance of our agshRNA design by evaluating antiviral efficacies of agshRNAs in cells infected with different viruses. Using the agshRNA targeting EV71 as an example, we showed that the anti-EV71 effect of agshRNA was more potent compared with the corresponding siRNA and shRNA. Moreover, the antiviral effect of agshRNA is dependent on AGO2-processed guide RNA, which can load into the RNA-induced silencing complex (RISC). We also confirmed the antiviral effect of agshRNA in vivo. Together, this work develops a novel antiviral strategy that combines machine learning-based algorithm with agshRNA design to custom design antiviral agshRNAs with high efficiency.

The maternal-fetal interface shares similarities with tumor tissues in terms of the immune microenvironment. Normal pregnancy is maintained due to the immunosuppressed state, but pyroptosis induced by MITA can trigger the body’s immune response and disrupt the immunosuppressed state of the maternal-fetal interface, leading to abortion. In this study, we explored the role of MITA and TRIM38 in regulating pyroptosis and maintaining the immune tolerance of the maternal-fetal interface during pregnancy. Our findings show that the interaction between MITA and TRIM38 plays a crucial role in maintaining the immunosuppressed state of the maternal-fetal interface. Specifically, we observed that TRIM38-mediated K48 ubiquitination of MITA was higher in M2 macrophages, leading to low expression levels of MITA and thus inhibiting pyroptosis. Conversely, in M1 macrophages, the ubiquitination of K48 was lower, resulting in higher expression levels of MITA and promoting pyroptosis. Our results also indicated that pyroptosis played an important role in hindering the transformation of M1 to M2 and maintaining the immunosuppressed state of the maternal-fetal interface. These discoveries help elucidate the mechanisms that support the preservation of the immune tolerance microenvironment at the maternal-fetal interface, playing a vital role in ensuring successful pregnancy.

Apoptotic inhibition and immune evasion have particular importance to efficient viral infection, while a dilemma often faced by viruses is that inhibiting apoptosis can up-regulate antiviral immune signaling. Herein, we uncovered that in addition to inhibiting caspase-8/extrinsic apoptosis, human cytomegalovirus (HCMV)–encoded UL36 suppresses interferon regulatory factor 3 (IRF3)–dependent immune signaling by directly targeting IRF3 to abrogate IRF3 interaction with stimulator of interferon genes or TANK-binding kinase 1 and inhibit IRF3 phosphorylation/activation. Although UL36-mediated caspase-8/extrinsic apoptosis inhibition enhances immune signaling, the immunosuppressing activity of UL36 counterbalances this immunoenhancing “side effect” undesirable for virus. Furthermore, we used mutational analyses to show that only the wild-type, but not the UL36 mutant losing either inhibitory activity, is sufficient to support effective HCMV replication in cells, showing the functional importance of the dual inhibition by UL36 for the HCMV life cycle. Together, our findings demonstrate a sophisticated mechanism by which HCMV tightly controls innate immune signaling and extrinsic apoptosis for efficient infection.

Maternal-fetal interface shares similarities with tumor tissues in terms of immune microenvironment. Normal pregnancy is maintained due to the immunosuppressed state, but pyroptosis induced by MITA can trigger the body's immune response and disrupt the immunosuppressed state of the maternal-fetal interface, leading to abortion. In this study, we explored the role of MITA and TRIM38 in regulating pyroptosis and maintaining the immune tolerance of the maternal-fetal interface during pregnancy. Our findings show that the interaction between MITA and TRIM38 plays a crucial role in maintaining the immunosuppressed state of the maternal-fetal interface. Specifically, we observed that TRIM38-mediated K48 ubiquitination of MITA was higher in M2 macrophages, leading to low expression levels of MITA and thus, inhibiting pyroptosis. Conversely, in M1 macrophages, the ubiquitination of K48 was lower, resulting in higher expression levels of MITA and promoting pyroptosis. Our results also indicated that pyroptosis played a significant role in hindering the transformation of M1 to M2 and maintaining the immunosuppressed state of the maternal-fetal interface. The discoveries presented offer significant understanding into the mechanisms that support the preservation of the immune tolerance microenvironment at the maternal-fetal interface, playing a vital role in ensuring successful pregnancy results.

MITA (also called STING), a master regulator of DNA-mediated innate immune activation, is a potential therapeutic target for viral infection and virus-related diseases. The circRNA-mediated ceRNA network plays important roles in gene regulation and may contribute to many human diseases. However, the relationship between MITA and recurrent miscarriage (RM) and its circRNA-related regulatory mechanisms remain unclear. In this study, we validated that the decidual M1/M2 ratio was upregulated in RM patients, suggesting the vital roles of decidual macrophages in the pathogenesis of RM. We found that MITA was highly expressed in decidual macrophages of RM patients and validated that MITA could promote apoptosis and macrophage proinflammatory polarization in THP-1-derived macrophage (TDM) cells. Using circRNA sequencing and bioinformatic analysis, we screened out a novel circRNA (circKIAA0391) that is overexpressed in decidual macrophages of RM patients. Mechanistically, we found that circKIAA0391 could promote the apoptosis and proinflammatory polarization of TDM cells by sponging the miR-512-5p/MITA axis. This study provides a theoretical basis for further understanding the impact of MITA on macrophages and its circRNA-related regulatory mechanisms, which may have a crucial immunomodulatory function in the pathophysiology of RM.

Ferroptosis is a nonapoptotic form of programmed cell death that contributes to different neurological inflammatory diseases. However, whether HSV-1 induces ferroptosis in the CNS and the role of ferroptosis in viral pathogenesis remain unclear.

Echovirus 11 (ECHO 11) is a positive-strand RNA virus belonging to the genus Enterovirus of the family Picornaviridae. ECHO 11 infections can cause severe inflammatory illnesses in neonates, including severe acute hepatitis with coagulopathy. The activation of NLRP3 inflammasome is important for host defense against invading viruses, which also contributes to viral pathogenicity. However, whether and how ECHO 11 induces NLRP3 inflammasome activation remains unclear. In this study, we isolated a clinical strain of ECHO 11 from stools of an ECHO 11-infected newborn patient with necrotizing hepatitis. This virus shared 99.95% sequence identity with the previously published ECHO 11 sequence. The clinically isolated ECHO 11 can efficiently infect liver cells and strongly induces inflammation. Moreover, we showed that ECHO 11 induced IL-1β secretion and pyroptosis in cells and mouse bone marrow-derived macrophages (BMDMs). Furthermore, ECHO 11 infection triggered NLRP3 inflammasome activation, as evidenced by cleavages of GSDMD, pro-IL-1β and pro-caspase-1, and the release of LDH. ECHO 11 2B protein was required for NLRP3 inflammasome activation via interacting with NLRP3 to facilitate the inflammasome complex assembly. In vivo, expression of ECHO 11 2B also activated NLRP3 inflammasome in the murine liver. Besides, 2Bs of multiple EVs can also interact with NLRP3 and induce NLRP3 inflammasome activation. Together, our findings demonstrate a mechanism by which ECHO 11 induces inflammatory responses by activating NLRP3 inflammasome, providing novel insights into the pathogenesis of ECHO 11 infection.