Studies in mice and humans have revealed that the T cell, immunoglobulin, mucin (TIM) genes are associated with several atopic diseases. TIM-1 is a type I membrane protein that is expressed on T cells upon stimulation and has been shown to modulate their activation. In addition to a recently described interaction with dendritic cells, TIM-1 has also been identified as a phosphatidylserine recognition molecule, and several protein ligands have been proposed. Our understanding of its activity is complicated by the possibility that TIM-1 possesses multiple and diverse binding partners. In order to delineate the function of TIM-1, we generated monoclonal antibodies directed to a cleft formed within the IgV domain of TIM-1. We have shown here that antibodies that bind to this defined cleft antagonize TIM-1 binding to specific ligands and cells. Notably, these antibodies exhibited therapeutic activity in a humanized SCID model of experimental asthma, ameliorating inflammation, and airway hyperresponsiveness. Further experiments demonstrated that the effects of the TIM-1–specific antibodies were mediated via suppression of Th2 cell proliferation and cytokine production. These results demonstrate that modulation of the TIM-1 pathway can critically influence activated T cells in a humanized disease model, suggesting that TIM-1 antagonists may provide potent therapeutic benefit in asthma and other immune-mediated disorders.
Sanchaita Sriwal Sonar, Yen-Ming Hsu, Melanie Lynn Conrad, Gerard R. Majeau, Ayse Kilic, Ellen Garber, Yan Gao, Chioma Nwankwo, Gundi Willer, Jan C. Dudda, Hellen Kim, Véronique Bailly, Axel Pagenstecher, Paul D. Rennert, Harald Renz
Mechanism of TIM-1 antagonism.