The negative regulatory function of the lymphocyte-activation gene-3 co-receptor (CD223) on human T cells

Abstract Background and Aims Lymphocyte activation gene [LAG]-3 is an immune checkpoint and its expression identifies recently activated lymphocytes that may contribute to inflammation. We investigated the role of LAG-3 by analysing its expression and function in immune cells from blood and tissue of patients with ulcerative colitis [UC]. Methods The phenotypic properties of LAG-3+ T cells were determined by flow cytometry, qRT-PCR and single-cell RNA-sequencing. LAG-3+ cells were quantified and correlated with disease activity. The functional effects of LAG-3+ cells were tested using a depleting anti-LAG-3 monoclonal antibody [mAb] in a mixed lymphocyte reaction [MLR]. Results LAG-3+ cells in the blood were negligible. LAG-3+ lymphocytes were markedly increased in inflamed mucosal tissue and both frequencies of LAG-3+ T cells and transcript levels of LAG3 correlated with endoscopic severity. LAG-3 expression was predominantly on effector memory T cells, and single-cell RNA-sequencing revealed LAG3 expression in activated and cytokine-producing T cell subsets. Foxp3+CD25hi Tregs also expressed LAG-3, although most mucosal Tregs were LAG-3−. Mucosal LAG-3+ cells produced mainly interferon γ [IFNγ] and interleukin-17A. LAG-3+ cell numbers decreased in patients who responded to biologics, and remained elevated in non-responders. Treatment with a depleting anti-LAG-3 mAb led to a reduction in proliferation and IFNγ production in an MLR. Conclusions LAG-3+ cells are increased in the inflamed mucosa, predominantly on effector memory T cells with an activated phenotype and their cell numbers positively correlate with disease activity. Depleting LAG-3 eliminates activated proliferating T cells, and hence LAG-3 could be a therapeutic target in UC.

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Calcium-activated Potassium Channels Sustain Calcium Signaling in T Lymphocytes

Journal of Biological Chemistry ◽

10.1074/jbc.m011342200 ◽

2001 ◽

Vol 276 (15) ◽

pp. 12249-12256 ◽

Cited By ~ 130

Author(s):

Christopher M. Fanger ◽

Heiko Rauer ◽

Amber L. Neben ◽

Mark J. Miller ◽

Heike Rauer ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

T Lymphocyte ◽

Lymphocyte Activation ◽

Vital Role ◽

Dominant Negative ◽

Jurkat T Cells ◽

Human T Cells ◽

Calcium Activated Potassium Channels ◽

Small Conductance

To maintain Ca2+entry during T lymphocyte activation, a balancing efflux of cations is necessary. Using three approaches, we demonstrate that this cation efflux is mediated by Ca2+-activated K+(KCa) channels, hSKCa2in the human leukemic T cell line Jurkat and hIKCa1in mitogen-activated human T cells. First, several recently developed, selective and potent pharmacological inhibitors of KCachannels but not KVchannels reduce Ca2+entry in Jurkat and in mitogen-activated human T cells. Second, dominant-negative suppression of the native KCachannel in Jurkat T cells by overexpression of a truncated fragment of the clonedhSKCa2channel decreases Ca2+influx. Finally, introduction of the hIKCa1channel into Jurkat T cells maintains rapid Ca2+entry despite pharmacological inhibition of the native small conductance KCachannel. Thus, KCachannels play a vital role in T cell Ca2+signaling.

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Targeting Lymphocyte Activation Gene 3 to Reverse T-Lymphocyte Dysfunction and Improve Survival in Murine Polymicrobial Sepsis

The Journal of Infectious Diseases ◽

10.1093/infdis/jiaa191 ◽

2020 ◽

Vol 222 (6) ◽

pp. 1051-1061

Author(s):

Jing-sheng Lou ◽

Jia-feng Wang ◽

Miao-miao Fei ◽

Yan Zhang ◽

Jun Wang ◽

...

Keyword(s):

T Cells ◽

T Cell ◽

Cell Apoptosis ◽

Interleukin 2 ◽

Lymphocyte Activation ◽

Interferon Γ ◽

T Cell Apoptosis ◽

Cytokine Levels ◽

Lymphocyte Activation Gene

Abstract Background Lymphocyte activation gene 3 (LAG-3) is one of the immune checkpoint molecules, negatively regulating the T-cell reactions. The present study investigated the role of LAG-3 in sepsis-induced T-lymphocyte disability. Methods Mice sepsis was induced by cecal ligation and puncture (CLP). LAG-3 expression on some immune cells were detected 24 hours after CLP. LAG-3 knockout and anti–LAG-3 antibody were applied to investigate the effects on the survival, bacterial clearance. Cytokine levels, T-cell counts, and the presence of apoptosis (in blood, spleen, and thymus) were also determined. In vitro T-cell apoptosis, interferon γ secretion, and proliferation were measured. The expression of interleukin 2 receptor on T cells was also determined after CLP. Results LAG-3 was up-regulated on CD4+/CD8+ T, CD19+ B, natural killer, CD4+CD25+ regulatory T cells and dendritic cells. Both LAG-3 knockout and anti–LAG-3 antibody had a positive effect on survival and on blood or peritoneal bacterial clearance in mice undergoing CLP. Cytokine levels and T-cell apoptosis decreased in anti–LAG-3 antibody–treated mice. Induced T-cell apoptosis decreased, whereas interferon γ secretion and proliferation were improved by anti–LAG-3 antibody in vitro. Interleukin 2 receptor was up-regulated on T cells in both wild-type and LAG-3–knockout mice undergoing CLP. Conclusions LAG-3 knockout or anti–LAG-3 antibody blockade protected mice undergoing CLP from sepsis-associated immunodysfunction and may be a new target for the treatment.

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