DDX1, DDX21, and DHX36 helicases form a complex with the adaptor molecule TRIF to sense dsRNA in dendritic cells.

The innate immune system detects viral infection predominantly by sensing viral nucleic acids. We report the identification of a viral sensor, consisting of RNA helicases DDX1, DDX21, and DHX36, and the adaptor molecule TRIF, by isolation and sequencing of poly I:C-binding proteins in myeloid dendritic cells (mDCs). Knockdown of each helicase or TRIF by shRNA blocked the ability of mDCs to mount type I interferon (IFN) and cytokine responses to poly I:C, influenza A virus, and reovirus. Although DDX1 bound poly I:C via its Helicase A domain, DHX36 and DDX21 bound the TIR domain of TRIF via their HA2-DUF and PRK domains, respectively. This sensor was localized within the cytosol, independent of the endosomes. Thus, the DDX1-DDX21-DHX36 complex represents a dsRNA sensor that uses the TRIF pathway to activate type I IFN responses in the cytosol of mDCs.

Efficacy of Ustekinumab and Vedolizumab Among Postoperative Crohn's Disease Patients as Postoperative Prophylaxis and Rescue Therapy: Real-world Data.

BACKGROUND: Almost half of patients with Crohn's disease (CD) require bowel surgeries in their lifetime. Due to the high risk of postoperative disease recurrence and high rate of previous antitumor necrosis factor (anti-TNF) failure, often alternative therapy options such as ustekinumab (UST) and vedolizumab (VDZ) are used. We aimed to evaluate the efficacy of UST and VDZ among postoperative CD patients as postoperative prophylaxis and rescue therapy. METHODS: Consented CD patients who underwent initial ileocecal resection and were treated with UST and VDZ were included in this study. Demographics, clinical characteristics, health care utilization, endoscopy scores, and surgery outcomes were collected. Postoperative early CD recurrence was defined as a Rutgeerts endoscopic score ≥i2 within the first 2 years. The rescue therapy group was defined as patients who received either UST or VDZ after having Rutgeerts endoscopic score ≥i2 postoperatively. RESULTS: During 2009 to 2019, 98 CD patients were treated with UST or VDZ postoperatively. Postoperative early recurrence rates were 5% (n = 1 out of 20) and 6% (1 out of 15) for the UST and VDZ groups, respectively. Two patients from the UST group and 1 patient from the VDZ group required bowel surgery during follow-up with median drug exposure of 51 (95% confidence interval [CI], 29-61) and 30 (95% CI, 14-63) months, respectively; 55% and 69% of patients had at least 1 point of improvement on postoperative endoscopic Rutgeerts score, respectively, for UST and VDZ. Only 3 out of 40 and 1 out of 23 patients required bowel surgery during follow-up while receiving UST and VDZ as rescue therapy. CONCLUSIONS: Both UST and VDZ were effective as postoperative therapies either as prophylaxis or rescue therapy.

This retrospective 11-year data examines the efficacy of ustekinumab and vedolizumab among postoperative Crohn's disease patients. When utilizing postoperative Rutgeerts score, this study confirms that both ustekinumab and vedolizumab were effective as postoperative therapies either as prophylaxis or rescue therapy.

Lipopolysaccharide-mediated IL-10 transcriptional regulation requires sequential induction of type I IFNs and IL-27 in macrophages.

IL-10 is a potent anti-inflammatory molecule that regulates excessive production of inflammatory cytokines during an infection or tissue damage. Dysregulation of IL-10 is associated with a number of autoimmune diseases, and so, understanding the mechanisms by which IL-10 gene expression is regulated remains an important area of study. Macrophages represent a major source of IL-10, which is generated in response to TLR signaling as a feedback mechanism to curtail inflammatory response. In this study, we identify a signaling pathway in murine bone marrow-derived macrophages in which activation of TLR4 by LPS induces the expression of IL-10 through the sequential induction of type I IFNs followed by induction and signaling through IL-27. We demonstrate that IL-27 signaling is required for robust IL-10 induction by LPS and type I IFNs. IL-27 leads directly to transcription of IL-10 through the activation of two required transcription factors, STAT1 and STAT3, which are recruited to the IL-10 promoter. Finally, through systematic functional promoter-reporter analysis, we identify three cis elements within the proximal IL-10 promoter that play an important role in regulating transcription of IL-10 in response to IL-27.

Suppressing fatty acid synthase by type I interferon and chemical inhibitors as a broad spectrum anti-viral strategy against SARS-CoV-2.

SARS-CoV-2 is an emerging viral pathogen and a major global public health challenge since December of 2019, with limited effective treatments throughout the pandemic. As part of the innate immune response to viral infection, type I interferons (IFN-I) trigger a signaling cascade that culminates in the activation of hundreds of genes, known as interferon stimulated genes (ISGs), that collectively foster an antiviral state. We report here the identification of a group of type I interferon suppressed genes, including fatty acid synthase (FASN), which are involved in lipid metabolism. Overexpression of FASN or the addition of its downstream product, palmitate, increased viral infection while knockout or knockdown of FASN reduced infection. More importantly, pharmacological inhibitors of FASN effectively blocked infections with a broad range of viruses, including SARS-CoV-2 and its variants of concern. Thus, our studies not only suggest that downregulation of metabolic genes may present an antiviral strategy by type I interferon, but they also introduce the potential for FASN inhibitors to have a therapeutic application in combating emerging infectious diseases such as COVID-19.

Cellular Signaling Analysis shows antiviral, ribavirin-mediated ribosomal signaling modulation.

As antiviral drug resistance develops and new viruses emerge there is a pressing need to develop strategies to rapidly develop antiviral therapeutics. Here we use phospho-specific flow cytometry to assess perturbations of many different cellular signaling pathways during treatment with drug combinations that are highly effective in blocking Herpes simplex virus type 1 (HSV-1) infection. We discovered two antiviral drug combinations act on distinct signaling pathways, either STAT1 or S6 phosphorylation, to block HSV-1 infection. We focused on upregulation of S6 phosphorylation by HSV-1 infection, and our subsequent finding that ribavirin antagonizes this upregulation of S6 phosphorylation. We go on to show that the S6 kinase inhibitor SL0101 blocks HSV-1 replication in vitro and in an in vivo animal model of HSV-1 infection. Overall, we have used an unbiased analysis of cellular signaling pathways during treatment by antiviral drug combinations to discover a novel antiviral drug target against HSV-1 infection. The outcomes of the approach we present highlight the importance of analyzing how antiviral drugs modulate cellular and pathogen-induced signaling as a method to discover new drug therapy targets.

Poly I:C enhances susceptibility to secondary pulmonary infections by gram-positive bacteria.

Secondary bacterial pneumonias are a frequent complication of influenza and other respiratory viral infections, but the mechanisms underlying viral-induced susceptibility to bacterial infections are poorly understood. In particular, it is unclear whether the host's response against the viral infection, independent of the injury caused by the virus, results in impairment of antibacterial host defense. Here, we sought to determine whether the induction of an "antiviral" immune state using various viral recognition receptor ligands was sufficient to result in decreased ability to combat common bacterial pathogens of the lung. Using a mouse model, animals were administered polyinosine-polycytidylic acid (poly I:C) or Toll-like 7 ligand (imiquimod or gardiquimod) intranasally, followed by intratracheal challenge with Streptococcus pneumoniae. We found that animals pre-exposed to poly I:C displayed impaired bacterial clearance and increased mortality. Poly I:C-exposed animals also had decreased ability to clear methicillin-resistant Staphylococcus aureus. Furthermore, we showed that activation of Toll-like receptor (TLR)3 and Retinoic acid inducible gene (RIG-I)/Cardif pathways, which recognize viral nucleic acids in the form of dsRNA, both contribute to poly I:C mediated impairment of bacterial clearance. Finally, we determined that poly I:C administration resulted in significant induction of type I interferons (IFNs), whereas the elimination of type I IFN signaling improved clearance and survival following secondary bacterial pneumonia. Collectively, these results indicate that in the lung, poly I:C administration is sufficient to impair pulmonary host defense against clinically important gram-positive bacterial pathogens, which appears to be mediated by type I IFNs.