MHCII Cross-presentation as a Driver of CD4+ T Cell Responses to Poxviruses

MHCII 交叉呈递作为 CD4 T 细胞对痘病毒反应的驱动因素

• 批准号: 9198974
• 负责人: Laurence Crane Eisenlohr
• 金额: $ 56.46万
• 依托单位: CHILDREN'S HOSP OF PHILADELPHIA
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-07-15 至 2019-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9198974
• 关键词: Achievement; Adoptive Transfer; Anabolism; Antigen Presentation Pathway; Antigen-Presenting Cells; Antigens; Area; Autoimmune Diseases; Binding; Bioinformatics; Biological Assay; Biology; CD4 Positive T Lymphocytes; Catalysis; Cell membrane; Cell physiology; Cells; Clinical; Complex; Cross Presentation; Data; Dendritic Cells; Development; DsRed; Ectromelia; Epitopes; Eukaryota; Goals; Histocompatibility Antigens Class II; Host Defense; Human; Hybridomas; Image; Immune system; In Vitro; Infectious Ectromelia; Influenza; Investigation; Knock-out; Lead; Location; MHC Class I Genes; MHC Class II Genes; Mediating; Mediator of activation protein; Modeling; Mus; Pathogenesis; Pathway interactions; Peptide Library; Peptide/MHC Complex; Peptides; Play; Poxviridae; Process; Proteins; Reagent; Reporting; Research; Resistance; Role; Scheme; Series; Smallpox Vaccine; Source; Specificity; Structure; Surface; Testing; Therapeutic; Vaccine Design; Vaccinia; Viral; Viral Antigens; Viral Proteins; Virion; Virulence; Virus; Work; anti-influenza; experimental study; extracellular; flu; gene product; immunoregulation; in vivo; insight; late endosome; novel; novel strategies; pathogen; protein aminoacid sequence; public health relevance; response; symposium

 DESCRIPTION (provided by applicant): By recognizing foreign peptides (epitopes) in combination with Major Histocompatibility Complex class II molecules (MHCII), CD4+ T lymphocytes (TCD4+) play a critical role in the adaptive responses to most viruses, including the poxviruses, which continue to pose a considerable threat to humans worldwide. According to a convention developed with nominal protein antigens, MHCII-bound peptides are derived from internalized material that is catabolized in the endocytic network and loaded onto nascent MHCII in the late endosome, the complex subsequently transiting to the plasma membrane. Previous and ongoing work in the Eisenlohr lab has demonstrated that this classical scheme contributes minimally to the activation of influenza (flu)-specific TCD4+. Catalysis of whole virions is inefficient and, instead, viral proteins synthesized within the infected antigen- presenting cell (APC) are the primary source of peptides, generated via a network of endogenous processing pathways and directly presented to flu-specific TCD4+. We have recently extended the work to poxviruses in order to explore the generality of these findings. Investigation of vaccinia (VACV) and ectromelia (ECTV) reveals the landscape to be far more complex. As with flu, exogenously provided poxvirions are also resistant to processing, necessitating biosynthesis of viral proteins. However, in contrast to flu, TCD4+ activation appears to depend primarily upon MHCII cross-presentation, in which the biosynthesized antigen is transferred from an infected cell to an uninfected APC. This is attributable to profound inhibition of direct presentation by the infected cell, particularly in the case of ECTV, a natural mouse pathogen. While direct disruption of MHC class I-restricted antigen processing and presentation is well known, it has rarely been reported for MHCII, and the degree and specificity of inhibition by poxviruses is unprecedented. Established work by the Roper lab has identified the A35 gene product of both VACV and ECTV as a major mediator of the inhibition, and preliminary data from the Hersperger lab implicates the B22 gene product as a potent co-conspirator. This Co-PI RO1 application, which combines expertise in antigen processing and presentation with that in poxvirus biology and pathogenesis, will extend these preliminary findings as follows: 1) Rigorously test the hypothesis both in vitro (Aim 1) and in vivo (Aim 2) that MHCII cross-presentation is the principal driver of TCD4+ responses to VACV- and ECTV-specific TCD4+ responses, 2) Determine the contributions of A35 and B22 to the block in direct presentation and identify other poxviral products that might provide complementary activity (Aim 3). 3) Identify the mechanisms underlying A35 and B22 inhibitory activities (Aim 4). These studies bring together three areas of high impact - TCD4+ recognition of viral antigens, poxvirus virulence, and viral subversion of MHCII antigen processing and presentation. Achievement of the aims will substantially enhance understanding of poxvirus pathogenesis and rational vaccine design, and could lead to novel experimental and clinical immunomodulatory strategies.

 描述（由申请人提供）：通过识别与主要组织相容性复合物II类分子（MHCII）组合的外源肽（表位），CD 4 + T淋巴细胞（TCD 4+）在对大多数病毒（包括痘病毒）的适应性应答中发挥关键作用，痘病毒继续对全世界人类构成相当大的威胁。根据用标称蛋白质抗原开发的惯例，MHCII结合肽衍生自内化的材料，所述内化的材料在内吞网络中被分解代谢并加载到晚期内体中的新生MHCII上，所述复合物随后转运到质膜。Eisenlohr实验室以前和正在进行的工作已经证明，这种经典的方案对流感特异性TCD 4+的激活贡献最小。整个病毒粒子的催化是低效的，相反，在感染的抗原呈递细胞（APC）内合成的病毒蛋白是肽的主要来源，通过内源性加工途径的网络产生并直接呈递给流感特异性T ⑶ 4+。我们最近将这项工作扩展到痘病毒，以探索这些发现的普遍性。对牛痘（VACV）和脱肢病（ECTV）的调查显示，景观要复杂得多。与流感一样，外源性痘病毒也对加工有抵抗力，需要病毒蛋白的生物合成。然而，与流感相反，TCD 4+活化似乎主要依赖于MHCII交叉呈递，其中生物合成的抗原从感染的细胞转移到未感染的APC。这是由于深刻的 抑制受感染细胞的直接呈递，特别是在ECTV的情况下， 鼠病原体虽然直接破坏MHC I类限制性抗原加工和呈递是众所周知的，但很少报道MHCII，并且痘病毒抑制的程度和特异性是前所未有的。罗珀实验室的既定工作已经确定VACV和ECTV的A35基因产物是抑制的主要介质，而来自赫斯珀格实验室的初步数据暗示B22基因产物是一个有力的同谋者。 该Co-PI RO 1应用将抗原加工和呈递方面的专业知识与痘病毒生物学和发病机制相结合，将这些初步发现扩展如下：1）在体外（目标1）和体内（目标2）严格检验假设，即MHCII交叉呈递是TCD 4+应答对VACV和ECTV特异性TCD 4+应答的主要驱动力，2）确定A35和B22在直接呈递中对阻断的贡献，并鉴定可能提供互补活性的其他痘病毒产物（目的3）。3)确定A35和B22抑制活性的机制（目标4）。 这些研究汇集了三个具有高度影响力的领域-病毒抗原的TCD 4+识别，痘病毒毒力和MHCII抗原加工和呈递的病毒颠覆。这些目标的实现将大大提高对痘病毒发病机制和合理疫苗设计的理解，并可能导致新的实验和临床免疫调节策略。