TIM4 Regulates the Anti-Islet Th2 Alloimmune Response.

The role of the novel costimulatory molecule TIM4 in anti-islet response is unknown. We explored TIM4 expression and targeting in Th1 (BALB/c islets into C57BL/6 mice) and Th2 (BALB/c islets into Tbet(-/-) C57BL/6 mice) models of anti-islet alloimmune response and in a model of anti-islet autoimmune response (diabetes onset in NOD mice). The targeting of TIM4, using the monoclonal antibody RMT4-53, promotes islet graft survival in a Th1 model, with 30% of the graft surviving in the long term; islet graft protection appears to be mediated by a Th1 to Th2 skewing of the immune response. Differently, in the Th2 model, TIM4 targeting precipitates graft rejection by further enhancing the Th2 response. The effect of anti-TIM4 treatment in preventing autoimmune diabetes was marginal with only minor Th1 to Th2 skewing. B-Cell depletion abolished the effect of TIM4 targeting. TIM4 is expressed on human B-cells and is upregulated in diabetic and islet-transplanted patients. Our data suggest a model in which TIM4 targeting promotes Th2 response over Th1 via B-cells. The targeting of TIM4 could become a component of an immunoregulatory protocol in clinical islet transplantation, aiming at redirecting the immune system toward a Th2 response.

Citation

Andrea Vergani, Francesca Gatti, Kang M Lee, Francesca D'Addio, Sara Tezza, Melissa Chin, Roberto Bassi, Ze Tian, Erxi Wu, Paola Maffi, Moufida Ben Nasr, James I Kim, Antonio Secchi, James F Markmann, David M Rothstein, Laurence A Turka, Mohamed H Sayegh, Paolo Fiorina. TIM4 Regulates the Anti-Islet Th2 Alloimmune Response. Cell transplantation. 2015;24(8):1599-1614

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PMID: 24612609

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