{"640323":{"#nid":"640323","#data":{"type":"event","title":"BioE PhD Defense Presentation- Zhou Yuan","body":[{"value":"\u003Cp\u003E\u003Cstrong\u003EAdvisor:\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDr. Cheng Zhu (Georgia Institute of Technology)\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003ECommittee:\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDr. Susan Thomas (Georgia Institute of Technology)\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDr. Michelle Krogsgaard (New York University)\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDr. Mandy Ford (Emory University)\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDr. Gabe Kwong (Georgia Institute of Technology)\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u003Cstrong\u003ERegulation of T-cell antigen recognition by melanoma tumor microenvironment and TCR-CD3 ectodomain interaction\u003C\/strong\u003E\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EDespite the critical role of CD8+ T cells in tumor clearance, their functions are impaired by immunosuppressive cells\/cytokines, through inhibitory receptors, and metabolic restrictions in the tumor microenvironment (TME). Targeting these suppressive pathways were shown to promote tumor clearance, yet unknown mechanisms may still exist curtailing the T cell responses. The T cell activation and anti-tumor response are initiated by the T cells receptor (TCR) recognizing antigen peptide presented by major histocompatibility complex (pMHC) molecules on antigen presenting cells (APC). Recent studies have demonstrated that comparing to in solution (or three-dimensional, 3D) kinetic measurements that uses purified TCR molecules, analysis of pMHC interacting with TCRs expressed on native T cells (or two-dimensional, 2D) provides a better prediction of T cell function and is able to capture perturbations of antigen recognition by T cell intrinsic and extrinsic mechanisms. In this study, we examined whether T cell antigen recognition is altered by the TME, and thus contributes to the T cell dysfunction. By testing the OT-I T cells from the murine B16F10 melanoma TME with their cognate antigen pMHC OVA:H2Kb, we showed that the TCR-pMHC 2D affinity is reduced in TME. The presence of tumor modulated TCR mechanosensing of antigen pMHC, converting a typical TCR-pMHC catch bond into slip bonds. The T cells from TME gave a reduced spreading on pMHC coated surface, with a decreased TCR-pMHC tension signal generated by spontaneous T cell pulling on pMHC at force over 4.7pN. The TME altered dynamic response of T cell CD3\u0026zeta; phosphorylation, and reduced level of calcium flux following in vitro stimulations. Using T cell in vitro activation, in vivo proliferation and ex vivo cytokine production as readouts, we showed that removing the TME restores T cell function that was impaired by this antigen inexperienced mechanism. Further analysis showed that nitration of TCR, which can be caused by presence of MDSCs in TME and induces T cell tolerance induced dysfunction, reduced TCR-pMHC 2D affinity. Presence of immunosuppressive Treg and cytokine TGF-\u0026beta; in TME is known to impair CD8+ T cell activation and function. We showed that in vivo TGF-\u0026beta; inhibition and CD4 depletion in tumor bearing animal partially restored the TME altered TCR-pMHC interaction. To summarize, we found that the impaired TCR-pMHC mechanosensing correlated with a reduced T cell function in TME, while this tumor antigen inexperienced suppression was functionally reversible. We also identified several immunosuppressive factors as the potential mechanisms of TME impairment on T cell antigen recognition.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003ETCR \u0026alpha; chain and \u0026beta; chain bind noncovalently to dimeric subunits CD3\u0026delta;\u0026epsilon;, CD3\u0026gamma;\u0026epsilon;, and CD3\u0026zeta;\u0026zeta; to form TCR complex. Upon TCR\u0026alpha;\u0026beta; engaging the antigen pMHC, this binding signal is transmitted through TCR-CD3 interaction, phosphorylates the immunoreceptor tyrosine-based activation motifs (ITAMs) on CD3 cytoplamic tails, which triggers the T cell activation. The interactions among TCR, CD3\u0026delta;\u0026epsilon; and CD3\u0026gamma;\u0026epsilon; ectodomains are weak in 2D affinities, with short-moderate duration of averaged lifetimes, however disrupting these interactions affects TCR complex stability, signaling and significantly reduces T cell function. In this study, we examed how this weak TCR-CD3 extracellular interaction severely impacts T cell function and whether this impact is through regulating T cell antigen recongition. We found that purified TCR proteins bind to a mixture of CD3\u0026delta;\u0026epsilon; and CD3\u0026gamma;\u0026epsilon; ectodomain proteins at an increased likelihood and increased average lifetime, comparing to TCR-CD3\u0026delta;\u0026epsilon; or TCR-CD3\u0026gamma;\u0026epsilon; interaction. This proved the existence of cooperativity among TCR-CD3 extracellular domain interactions. The antibody\/Fab targeting TCR and CD3 ectodomains can block TCR-CD3 extracellular interaction and reduce T cell functional response. We showed that the TCR-CD3 interaction blocking Fab treatments decreased TCR-pMHC 2D affinity and altered TCR-pMHC interaction force response profile. Together, these results indicate that TCR-CD3 extracellular interactions is enhanced by the cooperativity among the ectodomain interactions, and regulates T cell function through altering TCR mechanosensing.\u003C\/p\u003E\r\n\r\n\u003Cp\u003E\u0026nbsp;\u003C\/p\u003E\r\n\r\n\u003Cp\u003EIn this study, we identified impaired T cell antigen recognition as one mechanism of T cell dysfunction in TME. We also identified the cooperativity enhanced TCR-CD3 extracellular interaction as a regulating factor of T cell function by affecting T cell antigen recognition. The results greatly extend our understanding on how the T cell antigen recognition is regulated in physiological and pathological conditions, providing the molecular basis for developing pharmacological approaches to restore\/promote or suppress T cell response by regulating T cell antigen recognition.\u003C\/p\u003E\r\n","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EBioE PhD Defense Presentation-\u0026nbsp; \u0026quot;Regulation of T-cell antigen recognition by melanoma tumor microenvironment and TCR-CD3 ectodomain interaction\u0026quot;- Zhou Yuan\u003C\/p\u003E\r\n","format":"limited_html"}],"field_summary_sentence":[{"value":"\u0022Regulation of T-cell antigen recognition by melanoma tumor microenvironment and TCR-CD3 ectodomain interaction\u0022"}],"uid":"27917","created_gmt":"2020-10-19 13:54:47","changed_gmt":"2020-10-19 13:54:47","author":"Laura Paige","boilerplate_text":"","field_publication":"","field_article_url":"","field_event_time":{"event_time_start":"2020-10-29T10:30:00-04:00","event_time_end":"2020-10-29T12:30:00-04:00","event_time_end_last":"2020-10-29T12:30:00-04:00","gmt_time_start":"2020-10-29 14:30:00","gmt_time_end":"2020-10-29 16:30:00","gmt_time_end_last":"2020-10-29 16:30:00","rrule":null,"timezone":"America\/New_York"},"extras":[],"groups":[{"id":"65448","name":"Bioengineering Graduate Program"}],"categories":[],"keywords":[{"id":"172056","name":"go-BioE"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[{"id":"10377","name":"Career\/Professional development"}],"invited_audience":[{"id":"78761","name":"Faculty\/Staff"},{"id":"78771","name":"Public"},{"id":"78751","name":"Undergraduate students"}],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003ELaura Paige\u003C\/p\u003E\r\n\r\n\u003Cp\u003E404-385-6655\u003C\/p\u003E\r\n","format":"limited_html"}],"email":[],"slides":[],"orientation":[],"userdata":""}}}