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da Silveira BP, Barhoumi R, Bray JM, Cole-Pfeiffer HM, Mabry CJ, Burghardt RC, Cohen ND, Bordin AI. Impact of surface receptors TLR2, CR3, and FcγRIII on Rhodococcus equi phagocytosis and intracellular survival in macrophages. Infect Immun 2024; 92:e0038323. [PMID: 38018994 PMCID: PMC10790823 DOI: 10.1128/iai.00383-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 10/26/2023] [Indexed: 11/30/2023] Open
Abstract
The virulence-associated protein A (VapA) produced by virulent Rhodococcus equi allows it to replicate in macrophages and cause pneumonia in foals. It is unknown how VapA interacts with mammalian cell receptors, but intracellular replication of avirulent R. equi lacking vapA can be restored by supplementation with recombinant VapA (rVapA). Our objectives were to determine whether the absence of the surface receptors Toll-like receptor 2 (TLR2), complement receptor 3 (CR3), or Fc gamma receptor III (FcγRIII) impacts R. equi phagocytosis and intracellular replication in macrophages, and whether rVapA restoration of virulence in R. equi is dependent upon these receptors. Wild-type (WT) murine macrophages with TLR2, CR3, or FcγRIII blocked or knocked out (KO) were infected with virulent or avirulent R. equi, with or without rVapA supplementation. Quantitative bacterial culture and immunofluorescence imaging were performed. Phagocytosis of R. equi was not affected by blockade or KO of TLR2 or CR3. Intracellular replication of virulent R. equi was not affected by TLR2, CR3, or FcγRIII blockade or KO; however, avirulent R. equi replicated in TLR2-/- and CR3-/- macrophages but not in WT and FcγRIII-/-. rVapA supplementation did not affect avirulent R. equi phagocytosis but promoted intracellular replication in WT and all KO cells. By demonstrating that TLR2 and CR3 limit replication of avirulent but not virulent R. equi and that VapA-mediated virulence is independent of TLR2, CR3, or FcγRIII, our study provides novel insights into the role of these specific surface receptors in determining the entry and intracellular fate of R. equi.
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Affiliation(s)
- Bibiana Petri da Silveira
- Department of Large Animal Clinical Sciences, Equine Infectious Disease Laboratory, Texas A&M University, School of Veterinary Medicine & Biomedical Sciences, College Station, Texas, USA
| | - Rola Barhoumi
- Department of Veterinary Integrative Biosciences, Texas A&M University, School of Veterinary Medicine & Biomedical Sciences, College Station, Texas, USA
| | - Jocelyne M. Bray
- Department of Large Animal Clinical Sciences, Equine Infectious Disease Laboratory, Texas A&M University, School of Veterinary Medicine & Biomedical Sciences, College Station, Texas, USA
| | - Hannah M. Cole-Pfeiffer
- Department of Large Animal Clinical Sciences, Equine Infectious Disease Laboratory, Texas A&M University, School of Veterinary Medicine & Biomedical Sciences, College Station, Texas, USA
| | - Cory J. Mabry
- Department of Large Animal Clinical Sciences, Equine Infectious Disease Laboratory, Texas A&M University, School of Veterinary Medicine & Biomedical Sciences, College Station, Texas, USA
| | - Robert C. Burghardt
- Department of Veterinary Integrative Biosciences, Texas A&M University, School of Veterinary Medicine & Biomedical Sciences, College Station, Texas, USA
| | - Noah D. Cohen
- Department of Large Animal Clinical Sciences, Equine Infectious Disease Laboratory, Texas A&M University, School of Veterinary Medicine & Biomedical Sciences, College Station, Texas, USA
| | - Angela I. Bordin
- Department of Large Animal Clinical Sciences, Equine Infectious Disease Laboratory, Texas A&M University, School of Veterinary Medicine & Biomedical Sciences, College Station, Texas, USA
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Chen X, Qian Y, Yan F, Tu J, Yang X, Xing Y, Chen Z. 5'-triphosphate-siRNA activates RIG-I-dependent type I interferon production and enhances inhibition of hepatitis B virus replication in HepG2.2.15 cells. Eur J Pharmacol 2013; 721:86-95. [PMID: 24099962 DOI: 10.1016/j.ejphar.2013.09.050] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 09/06/2013] [Accepted: 09/22/2013] [Indexed: 12/25/2022]
Abstract
Hepatitis B virus (HBV) infection often results in acute or chronic viral hepatitis and other liver diseases including cirrhosis and hepatocellular carcinoma. Current therapies for HBV usually have severe side effects and can cause development of drug-resistant mutants. An alternative and safe immunotherapeutic approach for HBV infection is urgently needed for effective anti-HBV therapy. In this study, we propose a new strategy for anti-HBV therapy that activates type-I interferon (IFN) antiviral innate immunity through stimulating pattern-recognition receptors with RNA interference (RNAi) using a 5'-end triphosphate-modified small interfering RNA (3p-siRNA). We designed and generated a 3p-siRNA targeting overlapping region of S gene and P gene of the HBV genome at the 5'-end of pregenomic HBV RNA. Our results demonstrated that 3p-siRNA induced a RIG-I-dependent antiviral type-I IFN response when transfected into HepG2.2.15 cells that support HBV replication. The 3p-siRNA significantly inhibited HBsAg and HBeAg secretion from HepG2.2.15 cells in a RIG-I-dependent manner, and the antiviral effect of 3p-siRNA was superior to that of siRNA. Furthermore, 3p-siRNA had more pronounced inhibition effects on the replication of HBV DNA and the transcription of mRNA than that of siRNA. Finally, 3p-siRNA displayed antiviral activity with long-term suppression of HBV replication. In conclusion, our findings suggest that 3p-siRNA could act as a powerful bifunctional antiviral molecule with potential for developing a promising therapeutic against chronic HBV infection.
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Affiliation(s)
- Xiaojuan Chen
- Division of Infection and Immunity, Department of Electromagnetic and Laser Biology, Beijing Institute of Radiation Medicine, 27 Taiping Rd, Beijing 100850, China
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