Molecular Cloning,Characterization and Expression Analysis of Woodchuck Retinoic Acid-Inducible GeneⅠ

Cytosolic retinoic acid-inducible gene I（RIG-I） is an important innate immune RNA sensor and can induce antiviral cytokines, e.g., interferon-β（IFN-β）. Innate immune response to hepatitis B virus（HBV） plays a pivotal role in viral clearance and persistence. However, knowledge of the role that RIG-I plays in HBV infection is limited. The woodchuck is a valuable model for studying HBV infection. To characterize the molecular basis of woodchuck RIG-I（w RIG-I）, we analyzed the complete coding sequences（CDSs） of w RIG-I, containing 2778 base pairs that encode 925 amino acids. The deduced w RIG-I protein was 106.847 k D with a theoretical isoelectric point（p I） of 6.07, and contained three important functional structures [caspase activation and recruitment domains（CARDs）, DEx D/H-box helicases, and a repressor domain（RD）]. In woodchuck fibroblastoma cell line（WH12/6）, w RIG-I-targeted small interfering RNA（si RNA） down-regulated RIG-I and its downstrean effector–IFN-β transcripts under RIG-I＇ ligand, 5＇-ppp double stranded RNA（ds RNA） stimulation. We also measured m RNA levels of w RIG-I in different tissues from healthy woodchucks and in the livers from woodchuck hepatitis virus（WHV）-infected woodchucks. The basal expression levels of w RIG-I were abundant in the kidney and liver. Importantly, w RIG-I was significantly up-regulated in acutely infected woodchuck livers, suggesting that RIG-I might be involved in WHV infection. These results may characterize RIG-I in the woodchuck model, providing a strong basis for further study on RIG-I-mediated innate immunity in HBV infection.

Downregulation of Astrocyte Elevated Gene-1 Expression Combined with All-Trans Retinoic Acid Inhibits Development of Vasculogenic Mimicry and Angiogenesis in Glioma

Objective This study aimed to investigate the effects of downregulating astrocyte elevated gene-1(AEG-1)expression combined with all-trans retinoic acid(ATRA)on vasculogenic mimicry(VM)formation and angiogenesis in glioma.Methods U87 glioma cells were transfected with AEG-1 shRNA lentiviral vectors(U87-siAEG-1)and incubated in a medium containing 20µmol/L ATRA.Matrigel-based tube formation assay was performed to evaluate VM formation,and the cell counting kit-8(CCK-8)assay was used to analyze the proliferation of glioma cells in vitro.Reverse transcription-quantitative polymerase chain reaction and Western blot analysis were used to investigate the mRNA and protein expression of related genes,respectively.Glioma xenograft models were generated via subcutaneous implantation of glioma cells in nude mice.Tumor-bearing mice received an intraperitoneal injection of ATRA(10 mg/kg per day).Immunohistochemistry was used to evaluate the expression of related genes and the microvessel density(MVD)in glioma xenograft models.CD34/periodic acid-Schiff double staining was performed to detect VM channels in vivo.The volume and weight of tumors were measured,and a tumor growth curve was drawn to evaluate tumor growth.Results A combination of ATRA intervention and downregulation of AEG-1 expression significantly inhibited the proliferation of glioma cells in vitro and glioma VM formation in vitro and in vivo.It also significantly decreased MVD and inhibited tumor growth.Further,the expression levels of matrix metalloproteinase(MMP)-2,MMP-9,vascular endothelial-cadherin(VE-cadherin),and vascular endothelial growth factor(VEGF)in glioma significantly decreased in vivo and in vivo.Conclusion Hence,a combinatorial approach might be effective in treating glioma through regulating MMP-2,MMP-9,VEGF,and VE-cadherin expression.

Andrographolide as An Anti-H1N1 Drug and the Mechanism Related to Retinoic Acid-Inducible Gene-I-Like Receptors Signaling Pathway

Objective： To observe the anti-virus effects of andrographolide （AD） on the retinoic acid-inducible gene-I （RIG-I）-Iike receptors （RLRs） signaling pathway when immunological cells were infected with HIN1. Methods： Leukomonocyte was obtained from umbilical cord blood by Ficoll density gradient centrifugation, and immunological cells were harvested after cytokines stimulation. Virus infected cell model was established by H1N1 co-cultured with normal human bronchial epithelial cell line （16HBE）. The optimal concentration of AD was defined by methyl-thiazolyl-tetrazolium （MTT） assay. After the virus infected cell model was established, AD was added into the medium as a treatment intervention. After 24-h co-culture, cell supernatant was collected for interferon gamma （IFN- ~, ） and interleukin-4 （IL-4） enzyme-linked immunosorbent assay （ELISA） detection while immunological cells for real-time polymerase chain reaction （RT-PCR）. Results： The optimal concentration of AD for anti-virus effect was 250 μg/mL. IL-4 and IFN-γ in the supernatant and mRNA levels in RLRs pathway increased when cells was infected by virus, RIG-I, IFN-13 promoter stimulator-1 （IPS-1）, interferon regulatory factor （IRF）-7, IRF-3 and nuclear transcription factor K B （NF- K B） mRNA levels increased significantly （P〈0.05）. When AD was added into co-culture medium, the levels of IL-4 and IFN-γ were lower than those in the non-interference groups and the mRNA expression levels decreased, RIG-I, IPS-1, IRF-7, IRF-3 and NF- K B decreased significantly in each group with significant statistic differences （P〈0.05）. Conclusions： The RLRs mediated viral recognition provided a potential molecular target for acute viral infections and andrographolide could ameliorate H1N1 virus-induced cell mortality. And the antiviral effects might be related to its inhibition of viral-induced activation of the RLRs signaling pathway.

Effect of different forms of selenium in osteoporosis rat model induced by retinoic acid

Osteoporosis is a typical physiological disease,the main symptoms of which are brittle fracture,bone pain and easily deformed.As an individual ages,the prevalence of osteoporosis increases year by year.In the present study,selenium with antioxidant,immunomodulatory and anti-tumor effects was used to prevent osteoporosis induced by retinoic acid.The serum calcium contents in the selenium-treated groups(sodium selenite and selenomethionine)were significantly higher(P<0.05)than those in the model group in both the prevention and treatment studies.After pre-vention,glutamic-oxalacetic transaminase transaminase(GOT),glutamate transaminase(GPT),alkaline phosphatase(ALP)and tartrate-resistant acid phosphatase(TRACP)levels were significantly(P<0.05)decreased.In the treatment study,the serum calcium and phosphorus contents of the rats increased after selenium treatment.There was no significant change(P>0.05)in the activity of GOT and GPT.The content of ALP decreased obviously and the TRACP enzyme activity increased.Overall,these results showed that different forms of selenium compounds have great potential in preventing and treating osteoporosis.

(-)-Epigallocatechin-3-gallate enhances poly I:C-induced interferon-λ1 production and inhibits hepatitis C virus replication in hepatocytes

AIM To investigate the effect of(-)-epigallocatechin-3-gallate(EGCG) on polyinosinic-polycytidylic acid(poly I:C)-triggered intracellular innate immunity against hepatitis C virus(HCV) in hepatocytes. METHODS A cell culture model of HCV infection was generated by infecting a hepatoma cell line, Huh7, with HCV JFH-1 strain(JFH-1-Huh7). Poly I:C with a high molecular weight and EGCG were used to stimulate the JFH-1-Huh7 cells. Real-time reverse transcription-polymerase chain reaction was used to detect the expression levels of intracellular m RNAs and of intracellular and extracellular HCV RNA. Enzyme-linked immunosorbent assay was used to evaluate the interferon(IFN)-λ1 protein level in the cell culture supernatant. Immunostaining was used to examine HCV core protein expression in Huh7 cells.RESULTS Our recent study showed that HCV replication could impair poly I:C-triggered intracellular innate immune responses in hepatocytes. In the current study, we showed that EGCG treatment significantly increased the poly I:C-induced expression of Toll-like receptor 3(TLR3), retinoic acid-inducible gene I, and IFN-λ1 in JFH-1-Huh7 cells. In addition, supplementation with EGCG increased the poly I:C-mediated antiviral activity in JFH-1-Huh7 cells at the intracellular and extracellular HCV RNA and protein levels. Further investigation of the mechanisms showed that EGCG treatment significantly enhanced the poly I:C-induced expression of IFN-regulatory factor 9 and several antiviral IFNstimulated genes, including ISG15, ISG56, myxovirus resistance A, and 2'-5'-oligoadenylate synthetase 1, which encode the key antiviral elements in the IFN signaling pathway. CONCLUSION Our observations provide experimental evidence that EGCG has the ability to enhance poly I:C-induced intracellular antiviral innate immunity against HCV replication in hepatocytes.

Paramyxovirus evasion of innate immunity: Diverse strategies for common targets

The paramyxoviruses are a family of > 30 viruses that variously infect humans, other mammals and fish to cause diverse outcomes, ranging from asymptomatic to lethal disease, with the zoonotic paramyxoviruses Nipah and Hendra showing up to 70% case-fatality rate in humans. The capacity to evade host immunity is central to viral infection, and paramyxoviruses have evolved multiple strategies to overcome the host interferon(IFN)-mediated innate immune response through the activity of their IFN-antagonist proteins. Although paramyxovirus IFN antagonists generally target common factors of the IFN system, including melanoma differentiation associated factor 5, retinoic acid-inducible gene-I, signal transducers and activators of transcription(STAT)1 and STAT2, and IFN regulatory factor 3, the mechanisms of antagonism show remarkable diversity between different genera and even individual members of the same genus; the reasons for this diversity, however, are not currently understood. Here, we review the IFN antagonism strategies of paramyxoviruses, highlighting mechanistic differences observed between individual species and genera. We also discuss potential sources of this diversity, including biological differences in the host and/or tissue specificity of different paramyxoviruses, and potential effects of experimental approaches that have largely relied on in vitrosystems. Importantly, recent studies using recombinant virus systems and animal infection models are beginning to clarify the importance of certain mechanisms of IFN antagonism to in vivo infections, providing important indications not only of their critical importance to virulence, but also of their potential targeting for new therapeutic/vaccine approaches.

RIG-I,a novel DAMPs sensor for myoglobin,activates NF-κB/caspase-3 signaling in CS-AKI model

Background:Acute kidney injury(AKI)is the main life-threatening complication of crush syndrome(CS),and myoglobin is accepted as the main pathogenic factor.The pattern recognition receptor retinoicacid-inducible gene I(RIG-I)has been reported to exert anti-viral effects function in the innate immune response.However,it is not clear whether RIG-I plays a role in CS-AKI.The present research was carried out to explore the role of RIG-I in CS-AKI.Methods:Sprague-Dawley rats were randomly divided into two groups:the sham and CS groups(n=12).After administration of anesthesia,the double hind limbs of rats in the CS group were put under a pressure of 3 kg for 16 h to mimic crush conditions.The rats in both groups were denied access to food and water.Rats were sacrificed at 12 h or 36 h after pressure was relieved.The successful establishment of the CS-AKI model was confirmed by serum biochemical analysis and renal histological examination.In addition,RNA sequencing was performed on rat kidney tissue to identify molecular pathways involved in CS-AKI.Furthermore,NRK-52 E cells were treated with 200μmol/L ferrous myoglobin to mimic CS-AKI at the cellular level.The cells and cell supernatant samples were collected at 6 h or 24 h.Small interfering RNAs(siRNA)was used to knock down RIG-I expression.The relative expression levels of molecules involved in the RIG-I pathway in rat kidney or cells samples were measured by quantitative real-time PCR(qPCR),Western blotting analysis,and immunohistochemistry(IHC)staining.Tumor necrosis factor-α(TNF-α)was d etected by ELISA.Co-immunoprecipitation(Co-IP)assays were used to detect the interaction between RIG-I and myoglobin.Results:RNA sequencing of CS-AKI rat kidney tissue revealed that the different expression of RIG-I signaling pathway.qPCR,Western blotting,and IHC assays showed that RIG-I,nuclear factor kappa-B(NF-κB)P65,p-P65,and the a poptotic marker caspase-3 and cleaved caspase-3 were up-regulated in the CS group(P<0.05).However,the levels of interferon regulatory factor 3(IRF3),p-IRF3 and the antiviral factor interferon-beta(IFN-β)showed no significant c hanges between the sham and CS groups.Co-IP assays showed the interaction between RIG-I and myoglobin in the kidneys of the CS group.Depletion of RIG-I could alleviate the myoglobin induced expression of apoptosis-associated molecules via the NF-κB/caspase-3 axis.C onclusions:RIG-I is a novel damage-associated molecular patterns(DAMPs)sensor for myoglobin and participates in the NF-κB/caspase-3 signaling pathway in CS-AKI.In the development of CS-AKI,specific intervention in the RIG-I p athway might be a potential therapeutic strategy for CS-AKI.

Differential roles of RIG-Ⅰ like receptors in SARS-CoV-2 infection

Retinoic acid-inducible gene Ⅰ (RIG-Ⅰ) and melanoma differentiation-associated protein 5 (MDA5) sense viral RNA and activate antiviral immune responses.Herein we investigate their functions in human epithelial cells,the primary and initial target of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).A deficiency in MDA5,RIG-Ⅰ or mitochondrial antiviral signaling protein (MAVS) enhanced viral replication.The expression of the type I/III interferon(IFN) during infection was impaired in MDA5;and MAVS;,but not in RIG-Ⅰ;,when compared to wild type (WT) cells.The mRNA level of full-length angiotensin-converting enzyme 2 (ACE2),the cellular entry receptor for SARS-CoV-2,was approximately 2.5-fold higher in RIG-Ⅰ;than WT cells.These data demonstrate MDA5 as the predominant SARS-CoV-2 sensor,IFN-independent induction of ACE2 and anti-SARS-CoV-2 role of RIG-Ⅰ in epithelial cells.

Between Scylla and Charybdis:The role of the human immune system in the pathogenesis of hepatitis C

Hepatitis C virus(HCV)frequently elicits only mild immune responses so that it can often establish chronic infection.In this case HCV antigens persist and continue to stimulate the immune system.Antigen persistence then leads to profound changes in the infected host’s immune responsiveness,and eventually contributes to the pathology of chronic hepatitis.This topic highlight summarizes changes associated with chronic hepatitis C concerning innate immunity(interferons,natural killer cells),adaptive immune responses(immunoglobulins,T cells,and mechanisms of immune regulation(regulatory T cells).Our overview clarifies that a strong anti-HCV immune response is frequently associated with acute severe tissue damage.In chronic hepatitis C,however,the effector arms of the immune system either become refractory to activation or take over regulatory functions.Taken together these changes in immunity may lead to persistent liver damage and cirrhosis.Consequently,effector arms of the immune system will not only be considered with respect to antiviral defence but also as pivotal mechanisms of inflammation,necrosis and progression to cirrhosis.Thus,avoiding Scylla-a strong,sustained antiviral immune response with inital tissue damage-takes the infected host to virus-triggered immunopathology,which ultimately leads to cirrhosis and liver cancerthe realm of Charybdis.