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Studying the biology of cytotoxic T lymphocytes in vivo with a fluorescent granzyme B-mTFP knock-in mouse.

ABSTRACT: Understanding T cell function in vivo is of key importance for basic and translational immunology alike. To study T cells in vivo, we developed a new knock-in mouse line, which expresses a fusion protein of granzyme B, a key component of cytotoxic granules involved in T cell-mediated target cell-killing, and monomeric teal fluorescent protein from the endogenous Gzmb locus. Homozygous knock-ins, which are viable and fertile, have cytotoxic T lymphocytes with endogeneously fluorescent cytotoxic granules but wild-type-like killing capacity. Expression of the fluorescent fusion protein allows quantitative analyses of cytotoxic granule maturation, transport and fusion in vitro with super-resolution imaging techniques, and two-photon microscopy in living knock-ins enables the visualization of tissue rejection through individual target cell-killing events in vivo. Thus, the new mouse line is an ideal tool to study cytotoxic T lymphocyte biology and to optimize personalized immunotherapy in cancer treatment.

SUBMITTER: Chitirala P

PROVIDER: S-EPMC7375811 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature

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Studying the biology of cytotoxic T lymphocytes in vivo with a fluorescent granzyme B-mTFP knock-in mouse.

Chitirala Praneeth P Chang Hsin-Fang HF Martzloff Paloma P Harenberg Christiane C Ravichandran Keerthana K Abdulreda Midhat H MH Berggren Per-Olof PO Krause Elmar E Schirra Claudia C Leinders-Zufall Trese T Benseler Fritz F Brose Nils N Rettig Jens J

eLife 20200722

Understanding T cell function in vivo is of key importance for basic and translational immunology alike. To study T cells in vivo, we developed a new knock-in mouse line, which expresses a fusion protein of granzyme B, a key component of cytotoxic granules involved in T cell-mediated target cell-killing, and monomeric teal fluorescent protein from the endogenous <i>Gzmb</i> locus. Homozygous knock-ins, which are viable and fertile, have cytotoxic T lymphocytes with endogeneously fluorescent cyto ...[more]

PMID: 32696761

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Project description:BackgroundType I interferons (IFN-I) have recently emerged as key regulators of tumor response to chemotherapy and immunotherapy. However, IFN-I function in cytotoxic T lymphocytes (CTLs) in the tumor microenvironment is largely unknown.MethodsTumor tissues and CTLs of human colorectal cancer patients were analyzed for interferon (alpha and beta) receptor 1 (IFNAR1) expression. IFNAR1 knock out (IFNAR-KO), mixed wild type (WT) and IFNAR1-KO bone marrow chimera mice, and mice with IFNAR1 deficiency only in T cells (IFNAR1-TKO) were used to determine IFN-I function in T cells in tumor suppression. IFN-I target genes in tumor-infiltrating and antigen-specific CTLs were identified and functionally analyzed.ResultsIFNAR1 expression level is significantly lower in human colorectal carcinoma tissue than in normal colon tissue. IFNAR1 protein is also significantly lower on CTLs from colorectal cancer patients than those from healthy donors. Although IFNAR1-KO mice exhibited increased susceptibility to methylcholanthrene-induced sarcoma, IFNAR1-sufficient tumors also grow significantly faster in IFNAR1-KO mice and in mice with IFNAR1 deficiency only in T cells (IFNAR1-TKO), suggesting that IFN-I functions in T cells to enhance host cancer immunosurveillance. Strikingly, tumor-infiltrating CTL levels are similar between tumor-bearing WT and IFNAR1-KO mice. Competitive reconstitution of mixed WT and IFNAR1-KO bone marrow chimera mice further determined that IFNAR1-deficient naïve CTLs exhibit no deficiency in response to vaccination to generate antigen-specific CTLs as compared to WT CTLs. Gene expression profiling determined that Gzmb expression is down-regulated in tumor-infiltrating CTLs of IFNAR1-KO mice as compared to WT mice, and in antigen-specific IFNAR1-KO CTLs as compared to WT CTLs in vivo. Mechanistically, we determined that IFN-I activates STAT3 that binds to the Gzmb promoter to activate Gzmb transcription in CTLs.ConclusionIFN-I induces STAT3 activation to activate Gzmb expression to enhance CTL effector function to suppress tumor development. Human colorectal carcinoma may use down-regulation of IFNAR1 on CTLs to suppress CTL effector function to evade host cancer immunosurveillance.

Dataset Information

Studying the biology of cytotoxic T lymphocytes in vivo with a fluorescent granzyme B-mTFP knock-in mouse.

Publications

Studying the biology of cytotoxic T lymphocytes in vivo with a fluorescent granzyme B-mTFP knock-in mouse.

Similar Datasets

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