Inosine:A broad-spectrum anti-inflammatory against SARS-CoV-2 infection-induced acute lung injury via suppressing TBK1 phosphorylation

Severe acute respiratory syndrome coronavirus 2(SARS-CoV-2)-induced cytokine storms constitute the primary cause of coronavirus disease 19(COVID-19)progression,severity,criticality,and death.Glucocorticoid and anti-cytokine therapies are frequently administered to treat COVID-19,but have limited clinical efficacy in severe and critical cases.Nevertheless,the weaknesses of these treatment modalities have prompted the development of anti-inflammatory therapy against this infection.We found that the broad-spectrum anti-inflammatory agent inosine downregulated proinflammatory interleukin(IL)-6,upregulated anti-inflammatory IL-10,and ameliorated acute inflammatory lung injury caused by multiple infectious agents.Inosine significantly improved survival in mice infected with SARS-CoV-2.It indirectly impeded TANK-binding kinase 1(TBK1)phosphorylation by binding stimulator of interferon genes(STING)and glycogen synthase kinase-3β(GSK3β),inhibited the activation and nuclear translocation of the downstream transcription factors interferon regulatory factor(IRF3)and nuclear factor kappa B(NF-κB),and downregulated IL-6 in the sera and lung tissues of mice infected with lipopolysaccharide(LPS),H1N1,or SARS-CoV-2.Thus,inosine administration is feasible for clinical anti-inflammatory therapy against severe and critical COVID-19.Moreover,targeting TBK1 is a promising strategy for inhibiting cytokine storms and mitigating acute inflammatory lung injury induced by SARS-CoV-2 and other infectious agents.

Flk1胞外1-3区基因的克隆及核酸疫苗的构建

目的 :克隆并构建小鼠 Flk1胞外 1 - 3区核酸疫苗 ,并检验疫苗引起特异性免疫反应的能力。方法 :RT- PCR克隆 Flk1胞外 1 - 3区 ,构建核酸疫苗 pc DNA3.1 ( + ) -Flk1 Domain1 - 3,脂质体转染 COS7细胞 ,western- bolt检测表达 ;疫苗免疫小鼠 ;以小鼠血管内皮细胞为靶细胞 ,以免疫的小鼠脾细胞作为效应细胞 ,采用标准 4h51Cr释放法计算 CTL特异性杀伤率。结果 :扩增出 1 2 5 2 bp片段。疫苗 DNA自动测序证明所获基因片段序列阅读框架正确。Western- blot检测转染疫苗的 COS7细胞显示细胞中有分子质量为 44k Da的蛋白表达 ;疫苗组与对照组比较 ,CTL杀伤率差异有显著性。结论 :pc DNA3.1 ( + ) Flk1 -Domain1 - 3核酸疫苗可有效的引起针对 Flk1的免疫反应。

TANK结合激酶1在抗病毒免疫应答中的作用研究进展

TANK结合激酶1（TBK1）是I型干扰素合成过程中最为关键的蛋白激酶，在抗病毒固有免疫应答中发挥重要的作用。TBK1可以被RIG—I—MAVS、cGAS．STING和TLR3／4-TRIF抗病毒信号通路所活化，作为重要的节点蛋白，其活化受到磷酸化、泛素化、SUMO化等一系列机制复杂而精密的调控。本文对TBK1在抗病毒免疫应答中的作用及其调控机制的研究进展进行综述。

CD11c^+细胞特异性敲除TAK1对刀豆蛋白A诱导的免疫性肝损伤的影响

目的:探讨CD11c^+细胞中敲除TAK1对刀豆蛋白A(Con A)诱导的小鼠免疫性肝损伤的影响。方法:采用体内CD11c^+细胞中特异性敲除TAK1的C57BL/6小鼠,经鼠尾静脉注射Con A(12mg/kg)或生理盐水,分别作为Con A敲除组和生理盐水敲除组。另选C57BL/6小鼠,鼠尾静脉注射Con A(12mg/kg)或生理盐水,作为Con A对照组和生理盐水对照组。给药6h之后测定血清中丙氨酸氨基转移酶(ALT)、天门冬氨酸转移酶(AST)和乳酸脱氢酶(LDH)水平;检测肝、肾、胸腺等脏器系数并进行肝组织病理学观察和评分;测定血清中免疫反应相关细胞因子肿瘤坏死因子α(TNF-α)、干扰素γ(IFN-γ)、白细胞介素(IL-4/5/6/12)及肝组织中TNF-α和IFN-γ的表达水平。结果:与生理盐水对照组相比,Con A对照组ALT和LDH显著升高(P均<0.05),肝脏病理损伤明显加重,病理评分显著升高(P<0.05),血清中TNF-α、IFN-γ、IL-4/5/6水平和肝中TNF-α和IFN-γ均显著升高(P均<0.05);生理盐水敲除组肝中TNF-α水平显著降低(P<0.05)。与Con A对照组相比,Con A敲除组小鼠血清ALT、AST和LDH水平均显著升高(P<0.05),肝脏病理损伤明显加重,病理评分显著升高(P<0.05),肝组织IFN-γ水平,血清中TNF-α、IL-4和IL-6水平均显著升高(P均<0.05)。结论:在本实验条件下,CD11c^+细胞中敲除TAK1无明显肝损伤作用,但可加重Con A诱导的肝脏损伤,该作用可能与进一步激活免疫反应有关。

Ubiquitin-specific protease 24 promotes EV71 infection by restricting K63-linked polyubiquitination of TBK1

TANK-binding kinase 1(TBK1)is an essential protein kinase for activation of interferon regulatory factor 3(IRF3)and induction of the type I interferons(IFN-I).Although the biochemical regulation of TBK1 activation has been studied,little is known about how enterovirus 71(EV71)employs the deubiquitinases(DUBs)to regulate TBK1 activation for viral immune evasion.Here,we found that EV71 infection upregulated the expression of ubiquitinspecific protease 24(USP24).Further studies revealed that USP24 physically interacted with TBK1,and can reduce K63-linked polyubiquitination of TBK1.Knockdown of USP24 upregulated TBK1 K63-linked polyubiquitination,promoted the phosphorylation and nuclear translocation of IRF3,and in turn improved IFN-I production during EV71 infection.As a consequence,USP24 knockdown dramatically inhibited EV71 infection.This study revealed USP24 as a novel regulator of TBK1 activation,which promotes the understanding of immune evasion mechanisms of EV71 and could provide a potential strategy for treatment of EV71 infection.

TRAF7 negatively regulates the RLR signaling pathway by facilitating the K48-linked ubiquitination of TBK1

TANK-binding kinase 1(TBK1)is a nodal protein involved in multiple signal transduction pathways.In RNA virus-mediated innate immunity,TBK1 is recruited to the prion-like platform formed by MAVS and subsequently activates the transcription factors IRF3/7 and NF-κB to produce type I interferon(IFN)and proinflammatory cytokines for the signaling cascade.In this study,TRAF7 was identified as a negative regulator of innate immune signaling.TRAF7 interacts with TBK1 and promotes K48-linked polyubiquitination and degradation of TBK1 through its RING domain,impairing the activation of IRF3 and the production of IFN-β.In addition,we found that the conserved cysteine residues at position 131 of TRAF7 are necessary for its function toward TBK1.Knockout of TRAF7 could facilitate the activation of IRF3 and increase the transcript levels of downstream antiviral genes.These data suggest that TRAF7 negatively regulates innate antiviral immunity by promoting the K48-linked ubiquitination of TBK1.

Zika virus non-structural protein 4B interacts with DHCR7 to facilitate viral infection

Zika virus(ZIKV)evolves non-structural proteins to evade immune response and ensure efficient replication in the host cells.Cholesterol metabolic enzyme 7-dehydrocholesterol reductase(DHCR7)was recently reported to impact innate immune responses in ZIKV infection.However,the vital non-structural protein and mechanisms involved in DHCR7-mediated viral evasion are not well elucidated.In this study,we demonstrated that ZIKV infection facilitated DHCR7 expression.Notably,the upregulated DHCR7 in turn facilitated ZIKV infection and blocking DHCR7 suppressed ZIKV infection.Mechanically,ZIKV non-structural protein 4B(NS4B)interacted with DHCR7 to induce DHCR7 expression.Moreover,DHCR7 inhibited TANK-binding kinase 1(TBK1)and interferon regulatory factor 3(IRF3)phosphorylation,which resulted in the reduction of interferon-beta(IFN-β)and interferon-stimulated genes(ISGs)productions.Therefore,we propose that ZIKV NS4B binds to DHCR7 to repress TBK1 and IRF3 activation,which in turn inhibits IFN-βand ISGs,and thereby facilitating ZIKV evasion.This study broadens the insights on how viral non-structural proteins antagonize innate immunity to facilitate viral infection via cholesterol metabolic enzymes and intermediates.

Presence of Rare Variants is Associated with Poorer Survival in Chinese Patients with Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis(ALS)is a fatal neurodegenerative disorder with phenotypic and genetic heterogeneity.Recent studies have suggested an oligogenic basis of ALS,in which the co-occurrence of two or more genetic variants has additive or synergistic deleterious effects.To assess the contribution of possible oligogenic inheritance,we profiled a panel of 43 relevant genes in 57 sporadic ALS(sALS)patients and eight familial ALS(fALS)patients from five pedigrees in east China.We filtered rare variants using the combination of the Exome Aggregation Consortium,the 1000 Genomes and the HuaBiao Project.We analyzed patients with multiple rare variants in 43 known ALS causative genes and the genotype–phenotype cor-relation.Overall,we detected 30 rare variants in 16 different genes and found that 16 of the sALS patients and all the fALS patients examined harbored at least one variant in the investigated genes,among which two sALS and four fALS patients harbored two or more variants.Of note,the sALS patients with one or more variants in ALS genes had worse survival than the patients with no variants.Typically,in one fALS pedigree with three variants,the family member with three variants(Superoxide dismutase 1(SOD1)p.V48A,Optineurin(OPTN)p.A433V and TANK binding kinase 1(TBK1)p.R573H)exhibited much more severe disease phenotype than the member carrying one variant(TBK1 p.R573H).Our findings suggest that rare variants could exert a negative prognostic effect,thereby supporting the oligogenic inheritance of ALS.

Highlights of the 2nd International Symposium on Tribbles and Diseases: tribbles tremble in therapeutics for immunity, metabolism, fundamental cell biology and cancer

The Tribbles(TRIB) family of pseudokinase proteins has been shown to play key roles in cell cycle, metabolic diseases, chronic inflammatory disease, and cancer development. A better understanding of the mechanisms of TRIB pseudokinases could provide new insights for disease development and help promote TRIB proteins as novel therapeutic targets for drug discovery. At the 2 nd International Symposium on Tribbles and Diseases held on May 7–9, 2018 in Beijing, China, a group of leading Tribbles scientists reported their findings and ongoing studies about the effects of the different TRIB proteins in the areas of immunity, metabolism, fundamental cell biology and cancer. Here, we summarize important and insightful overviews from 4 keynote lectures, 13 plenary lectures and 8 short talks that took place during this meeting. These findings may offer new insights for the understanding of the roles of TRIB pseudokinases in the development of various diseases.