TIM3 is a context-dependent coregulator of cytotoxic T cell function

Hanin Alamir; Carissa C.W. Wong; Amal Alsubaiti; Grace L. Edmunds; Maryam Alismail; Lan Huynh; Yiwei Shi; Philip A. Lewis; Tressan Grant; Safaa Alsulaimani; James Boyd; Christopher J. Holland; David J. Morgan; Awen M. Gallimore; Christoph Wülfing

doi:10.1126/scisignal.adk4594

TIM3 is a context-dependent coregulator of cytotoxic T cell function

Hanin Alamir, Carissa C.W. Wong, Amal Alsubaiti, Grace L. Edmunds, Maryam Alismail, Lan Huynh, Yiwei Shi, Philip A. Lewis, Tressan Grant, Safaa Alsulaimani, James Boyd, Christopher J. Holland, David J. Morgan, Awen M. Gallimore, Christoph Wülfing

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Abstract

TIM3 is a coregulatory receptor that is highly abundant on multiple immune cell types, including T cells in response to prolonged exposure to antigen, and it marks functionally suppressed cytotoxic T lymphocytes (CTLs) in the tumor microenvironment. TIM3 exhibits inhibitory function in vivo but paradoxically has costimulatory T cell signaling capability in vitro. Here, we found that TIM3 directly inhibited the function of murine and human CTLs in direct interaction with target tumor cell spheroids. TIM3 regulated the ability of suppressed CTLs to polarize their actin cytoskeleton as a required step in cytolysis. Whereas the expression of the proposed TIM3 ligands CEACAM1 and galectin 9 in trans on target tumor cells enhanced TIM3 function, expression of CEACAM1 in cis on CTLs had the opposite effect. TIM3 functioned as an inhibitory receptor on spheroid-suppressed CTLs but not on active CTLs in a two-dimensional tissue culture model. Together, these data suggest that TIM3 enhances T cell function, serving as either a coinhibitory or costimulatory receptor depending on the functional context of the T cell on which it is expressed.

Original language	English
Article number	eadk4594
Pages (from-to)	eadk4594
Journal	Science Signaling
Volume	18
Issue number	905
DOIs	https://doi.org/10.1126/scisignal.adk4594
Publication status	Published - 23 Sept 2025

Data Availability Statement

Image analysis workflow files are available at Zenodo as detailed in the Materials and Methods. Spheroid imaging data were deposited in Dryad. the MS proteomics data have been deposited to the ProteomeXchange consortium through the PRiDe partnerrepository with the dataset identifier PXD057617. All other data needed to evaluate the conclusions in the paper are present in the paper or the Supplementary Material.

Funding

This work was supported by grants from the MRC (MR/N0137941/1 to C.C.W.W. and MR/W006308/1 to T.G. for the GW4 BIOMED MRC DTP), the Wellcome Trust (201254/Z/16/Z/ to G.L.E.), Cancer Research UK (DRCRPG-nOV21/100003 to A.M.G.), and Immunocore (to C.J.H. and C.W.). H.A., A.A., S.A., and M.A. were supported by the Ministry of Education of Saudi Arabia.

Funders	Funder number
Ministry of Education - Kingdom of Saudi Arabia
Medical Research Council	MR/N0137941/1, MR/W006308/1
The Wellcome Trust	201254/Z/16/Z/
Cancer Research UK	DRCRPG-nOV21/100003

ASJC Scopus subject areas

Biochemistry
Molecular Biology
Cell Biology

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Alamir, H., Wong, C. C. W., Alsubaiti, A., Edmunds, G. L., Alismail, M., Huynh, L., Shi, Y., Lewis, P. A., Grant, T., Alsulaimani, S., Boyd, J., Holland, C. J., Morgan, D. J., Gallimore, A. M., & Wülfing, C. (2025). TIM3 is a context-dependent coregulator of cytotoxic T cell function. Science Signaling, 18(905), eadk4594. Article eadk4594. https://doi.org/10.1126/scisignal.adk4594

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abstract = "TIM3 is a coregulatory receptor that is highly abundant on multiple immune cell types, including T cells in response to prolonged exposure to antigen, and it marks functionally suppressed cytotoxic T lymphocytes (CTLs) in the tumor microenvironment. TIM3 exhibits inhibitory function in vivo but paradoxically has costimulatory T cell signaling capability in vitro. Here, we found that TIM3 directly inhibited the function of murine and human CTLs in direct interaction with target tumor cell spheroids. TIM3 regulated the ability of suppressed CTLs to polarize their actin cytoskeleton as a required step in cytolysis. Whereas the expression of the proposed TIM3 ligands CEACAM1 and galectin 9 in trans on target tumor cells enhanced TIM3 function, expression of CEACAM1 in cis on CTLs had the opposite effect. TIM3 functioned as an inhibitory receptor on spheroid-suppressed CTLs but not on active CTLs in a two-dimensional tissue culture model. Together, these data suggest that TIM3 enhances T cell function, serving as either a coinhibitory or costimulatory receptor depending on the functional context of the T cell on which it is expressed.",

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TIM3 is a context-dependent coregulator of cytotoxic T cell function

Abstract

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