CD28-CD57+ T cells from head and neck cancer patients produce high levels of cytotoxic granules and type II interferon but are not senescent.

T lymphocytes expressing CD57 and lacking costimulatory receptors CD27/CD28 have been reported to accumulate with aging, chronic infection, and cancer. These cells are described as senescent, with inability to proliferate but enhanced cytolytic and cytokine-producing capacity. However, robust functional studies on these cells taken directly from cancer patients are lacking. We isolated these T cells and their CD27/28+ counterparts from blood and tumor samples of 50 patients with previously untreated head and neck cancer. Functional studies confirmed that these cells have enhanced ability to degranulate and produce IFN-γ. They also retain the ability to proliferate, thus are not senescent. These data suggest that CD27/28-CD57+ CD8+ T cells are a subset of highly differentiated, CD45RA+ effector memory (TEMRA) cells with retained proliferative capacity. Patients with > 34% of these cells among CD8+ T cells in the blood had a higher rate of locoregional disease relapse, suggesting these cells may have prognostic significance.

The role of KLRG1: a novel biomarker and new therapeutic target.

Killer cell lectin-like receptor G1 (KLRG1) is an immune checkpoint receptor expressed predominantly in NK and T-cell subsets that downregulates the activation and proliferation of immune cells and participates in cell-mediated immune responses. Accumulating evidence has demonstrated the importance of KLRG1 as a noteworthy disease marker and therapeutic target that can influence disease onset, progression, and prognosis. Blocking KLRG1 has been shown to effectively mitigate the effects of downregulation in various mouse tumor models, including solid tumors and hematologic malignancies. However, KLRG1 inhibitors have not yet been approved for human use, and the understanding of KLRG1 expression and its mechanism of action in various diseases remains incomplete. In this review, we explore alterations in the distribution, structure, and signaling pathways of KLRG1 in immune cells and summarize its expression patterns and roles in the development and progression of autoimmune diseases, infectious diseases, and cancers. Additionally, we discuss the potential applications of KLRG1 as a tool for tumor immunotherapy.

Dysregulation of peripheral and intratumoral KLRG1+ CD8+T cells is associated with immune evasion in patients with non-small-cell lung cancer.

OBJECTIVES: Killer cell lectin like receptor G1 (KLRG1) is identified as a co-inhibitory receptor for NK cells and antigen-experienced T cells. The role of KLRG1 in immune regulation in patients with non-small cell lung cancer (NSCLC) remains poorly understood. MATERIALS AND METHODS: We measured the proportion and immune function of KLRG1+CD8+T cells derived from peripheral blood in patients with NSCLC by flow cytometry. Besides, using data from the gene expression profiles and single-cell sequencing, we explored the expression and immune role of KLRG1 in tumor tissues of patients with NSCLC. We further determined the prognostic value of KLRG1 in terms of overall survival (OS) in NSCLC patients. RESULTS: We found that the proportion of KLRG1+CD8+T cells in peripheral blood significantly increased in patients with NSCLC as compared to those with benign pulmonary nodules and healthy donors. Peripheral KLRG1+CD8+T cell proportion was increased in elder subjects compared to that in younger ones, implying an immunosenescence phenotype. Moreover, the KLRG1+CD8+T cell levels were positively correlated with tumor size and TNM stage in the NSCLC cohort. In vitro stimulation experiments demonstrated that the KLRG1+CD8+T cells from peripheral blood expressed higher levels of Granzyme B and perforin than the KLRG1-CD8+ T cells. However, single-cell RNA sequencing data revealed that the KLRG1+CD8+ T cells were less infiltrated in tumor microenvironment and exhibited impaired cytotoxicity. The KLRG1 gene expression levels were significantly lower in tumor tissues than that in normal lung tissues, and were inversely correlated with CDH1 expression levels. Moreover, higher expression of CDH1 in tumor tissues predicted worse overall survival only in patients with KLRG1-high expression, but not in the KLRG1-low subset. CONCLUSION: This study demonstrates that KLRG1+CD8+T cells were associated with tumor immune evasion in NSCLC and suggests KLRG1 as a potential immunotherapy target.

Expression of HLA-DR and KLRG1 enhances the cytotoxic potential and cytokine secretion capacity of CD3+ T cells in tuberculosis patients.

BACKGROUND: Human T cells play an important role in immunity against tuberculosis (TB) infection. Activating receptor HLA-DR and inhibitory receptor KLRG1 are critical regulators of T cell function during viral infection and tumorigenesis, but they have been less studied in TB infection. METHODS: In this study, we explored the relationship between CD3+ T cell expression of HLA-DR and KLRG1 receptors and function against TB infection. Flow cytometry was conducted to assess the immunomodulatory effects of HLA-DR and KLRG1 receptors on CD3+ T cells in patients with different TB infection status. RESULTS: We found activating receptors HLA-DR, NKG2C, CD57 and NKP46, and inhibitory receptors KLRG1 and KIR on CD3+ T cells in different TB infection status showed different distribution patterns; the cytotoxic potential and cytokine secretion capacity of CD3+ T cells after Mtb-specific antigen stimulation were significantly enhanced in TB infection groups. Further studies revealed HLA-DR+ T and KLRG1+ T cells expressed higher activating and inhibitory receptors than the negative population. In addition, the expression of cytotoxic potential and cytokine secretion capacity of HLA-DR+ T and KLRG1+ T cells was significantly higher than that of HLA-DR- T and KLRG1- T cells. CONCLUSIONS: Expression of HLA-DR and KLRG1 enhances the cytotoxic potential and cytokine secretion capacity of CD3+ T cells in TB patients, suggesting CD3+ T cells expressing HLA-DR and KLRG1 are important effector cell phenotypes involved in the host anti-TB infection. HLA-DR and KLRG1 expressed by CD3+ T cells may be potential predictive markers of TB disease progression and clinical immune assessment.

PD-1 signaling uncovers a pathogenic subset of T cells in inflammatory arthritis.

BACKGROUND: PD-1 is an immune checkpoint on T cells, and interventions to block this receptor result in T cell activation and enhanced immune response to tumors and pathogens. Reciprocally, despite a decade of research, approaches to treat autoimmunity with PD-1 agonists have only had limited successful. To resolve this, new methods must be developed to augment PD-1 function beyond engaging the receptor. METHODS: We conducted a flow cytometry analysis of T cells isolated from the peripheral blood and synovial fluid of patients with rheumatoid arthritis. In addition, we performed a genome-wide CRISPR/Cas9 screen to identify genes associated with PD-1 signaling. We further analyzed genes involved in PD-1 signaling using publicly available bulk and single-cell RNA sequencing datasets. RESULTS: Our screen confirmed known regulators in proximal PD-1 signaling and, importantly, identified an additional 1112 unique genes related to PD-1 ability to inhibit T cell functions. These genes were strongly associated with the response of cancer patients to PD-1 blockades and with high tumor immune dysfunction and exclusion scores, confirming their role downstream of PD-1. Functional annotation revealed that the most significant genes uncovered were those associated with known immune regulation processes. Remarkably, these genes were considerably downregulated in T cells isolated from patients with inflammatory arthritis, supporting their overall inhibitory functions. A study of rheumatoid arthritis single-cell RNA sequencing data demonstrated that five genes, KLRG1, CRTAM, SLAMF7, PTPN2, and KLRD1, were downregulated in activated and effector T cells isolated from synovial fluids. Backgating these genes to canonical cytotoxic T cell signatures revealed PD-1+ HLA-DRHIGH KLRG1LOW T cells as a novel inflammatory subset of T cells. CONCLUSIONS: We concluded that PD-1+ HLA-DRHIGH KLRG1LOW T cells are a potential target for future PD-1 agonists to treat inflammatory diseases. Our study uncovers new genes associated with PD-1 downstream functions and, therefore, provides a comprehensive resource for additional studies that are much needed to characterize the role of PD-1 in the synovial subset of T cells.

PD1+TIGIT+2B4+KLRG1+ Cells Might Underlie T Cell Dysfunction in Patients Treated with BCMA-Directed Chimeric Antigen Receptor T Cell Therapy.

Chimeric antigen receptor T cell (CAR-T) therapy has shown rapid, frequent, and deep responses in patients with relapsed/refractory multiple myeloma (RRMM). However, relapse frequently occurs following CAR-T therapy, and the cause of this resistance is not well defined. Among the potential mechanisms of resistance, T cell intrinsic factors may be an important source of failure. Here we used spectral flow cytometry to identify the changes in T cell phenotypes in bone marrow aspirates at different stages of multiple myeloma progression, including cases that relapsed after anti-BCMA CAR-T therapy. We identified completely different T cell phenotypes in RRMM and post CAR-T relapse cases compared to healthy donors and earlier stages of multiple myeloma, novel double-negative CD3+ T cells in RRMM and CAR-T relapsed cases, and differences in CD8 T cell phenotype at the baseline between peripheral blood and bone marrow from healthy donors. We found that the majority of T cells in RRMM patients and significant T cell subsets in post-CAR-T relapsed patients expressed multiple coinhibitory markers, including PD1, TIGIT, 2B4, and KLRG1.

KLRG1 expression on natural killer cells is associated with HIV persistence, and its targeting promotes the reduction of the viral reservoir.

Human immunodeficiency virus (HIV) infection induces immunological dysfunction, which limits the elimination of HIV-infected cells during treated infection. Identifying and targeting dysfunctional immune cells might help accelerate the purging of the persistent viral reservoir. Here, we show that chronic HIV infection increases natural killer (NK) cell populations expressing the negative immune regulator KLRG1, both in peripheral blood and lymph nodes. Antiretroviral treatment (ART) does not reestablish these functionally impaired NK populations, and the expression of KLRG1 correlates with active HIV transcription. Targeting KLRG1 with specific antibodies significantly restores the capacity of NK cells to kill HIV-infected cells, reactivates latent HIV present in CD4+ T cells co-expressing KLRG1, and reduces the intact HIV genomes in samples from ART-treated individuals. Our data support the potential use of immunotherapy against the KLRG1 receptor to impact the viral reservoir during HIV persistence.

Morphological and molecular comparison of HIV-associated and sporadic inclusion body myositis.

OBJECTIVE: The molecular characteristics of sporadic inclusion body myositis (sIBM) have been intensively studied, and specific patterns on the cellular, protein and RNA level have emerged. However, these characteristics have not been studied in the context of HIV-associated IBM (HIV-IBM). In this study, we compared clinical, histopathological, and transcriptomic patterns of sIBM and HIV-IBM. METHODS: In this cross-sectional study, we compared patients with HIV-IBM and sIBM based on clinical and morphological features as well as gene expression levels of specific T-cell markers in skeletal muscle biopsy samples. Non-disease individuals served as controls (NDC). Cell counts for immunohistochemistry and gene expression profiles for quantitative PCR were used as primary outcomes. RESULTS: 14 muscle biopsy samples (7 HIV-IBM, 7 sIBM) of patients and 6 biopsy samples from NDC were included. Clinically, HIV-IBM patients showed a significantly lower age of onset and a shorter period between symptom onset and muscle biopsy. Histomorphologically, HIV-IBM patients showed no KLRG1+ or CD57+ cells, while the number of PD1+ cells did not differ significantly between the two groups. All markers were shown to be significantly upregulated at gene expression level with no significant difference between the IBM subgroups. CONCLUSION: Despite HIV-IBM and sIBM sharing important clinical, histopathological, and transcriptomic signatures, the presence of KLRG1+ cells discriminated sIBM from HIV-IBM. This may be explained by longer disease duration and subsequent T-cell stimulation in sIBM. Thus, the presence of TEMRA cells is characteristic for sIBM, but not a prerequisite for the development of IBM in HIV+ patients.

Uncovering the significance of expanded CD8+ large granular lymphocytes in inclusion body myositis: Insights into T cell phenotype and functional alterations, and disease severity.

Introduction: Inclusion body myositis (IBM) is a progressive inflammatory myopathy characterised by skeletal muscle infiltration and myofibre invasion by CD8+ T lymphocytes. In some cases, IBM has been reported to be associated with a systemic lymphoproliferative disorder of CD8+ T cells exhibiting a highly differentiated effector phenotype known as T cell Large Granular Lymphocytic Leukemia (T-LGLL). Methods: We investigated the incidence of a CD8+ T-LGL lymphoproliferative disorder in 85 IBM patients and an aged-matched group of 56 Healthy Controls (HC). Further, we analysed the phenotypical characteristics of the expanded T-LGLs and investigated whether their occurrence was associated with any particular HLA alleles or clinical characteristics. Results: Blood cell analysis by flow cytometry revealed expansion of T-LGLs in 34 of the 85 (40%) IBM patients. The T cell immunophenotype of T-LGLHIGH patients was characterised by increased expression of surface molecules including CD57 and KLRG1, and to a lesser extent of CD94 and CD56 predominantly in CD8+ T cells, although we also observed modest changes in CD4+ T cells and γδ T cells. Analysis of Ki67 in CD57+ KLRG1+ T cells revealed that only a small proportion of these cells was proliferating. Comparative analysis of CD8+ and CD4+ T cells isolated from matched blood and muscle samples donated by three patients indicated a consistent pattern of more pronounced alterations in muscles, although not significant due to small sample size. In the T-LGLHIGH patient group, we found increased frequencies of perforin-producing CD8+ and CD4+ T cells that were moderately correlated to combined CD57 and KLRG1 expression. Investigation of the HLA haplotypes of 75 IBM patients identified that carriage of the HLA-C*14:02:01 allele was significantly higher in T-LGLHIGH compared to T-LGLLOW individuals. Expansion of T-LGL was not significantly associated with seropositivity patient status for anti-cytosolic 5'-nucleotidase 1A autoantibodies. Clinically, the age at disease onset and disease duration were similar in the T-LGLHIGH and T-LGLLOW patient groups. However, metadata analysis of functional alterations indicated that patients with expanded T-LGL more frequently relied on mobility aids than T-LGLLOW patients indicating greater disease severity. Conclusion: Altogether, these results suggest that T-LGL expansion occurring in IBM patients is correlated with exacerbated immune dysregulation and increased disease burden.

KLRG1 is reduced on NK cells in SLE patients, inversely correlates with disease activity and is modulated by hydroxychloroquine in vitro.

OBJECTIVES: Killer cell lectin-like receptor G 1 (KLRG1), a transmembrane receptor with inhibitory capacity expressed in human immune cells, emerged as a novel susceptibility gene for systemic lupus erythematosus (SLE). The aim of this study was to investigate the expression of KLRG1 in SLE patients compared to healthy controls (HC) on both NK and T cells and to evaluate its possible involvement in SLE pathogenesis. METHODS: Eighteen SLE patients and twelve healthy controls were enrolled. Peripheral blood mononuclear cells (PBMCs) from these patients were phenotypically characterized by immunofluorescence and flow cytometry. The effect of the hydroxychloroquine (HCQ) in vitro on KLRG1 expression and its signaling mediated functions in NK cells were analyzed. RESULTS: KLRG1 expression was significantly reduced on the analyzed immune cell populations in SLE patients compared to HC, especially on total NK cells. Moreover, expression of KLRG1 on total NK cells inversely correlated with the SLEDAI-2K. A direct association between KLRG1 expression on NK cells and patients' treatment with HCQ was observed. In vitro treatment with HCQ increased KLRG1 expression on NK cells. In HC, KLRG1+ NK cells showed reduced degranulation and IFNγ production, while in SLE patient, this inhibition occurred only for the IFNγ production. CONCLUSION: With this study we revealed a reduced expression and an impaired function of KLRG1 on NK cells in SLE patients. These results suggest a possible role of KLRG1 in the pathogenesis of SLE and as a novel biomarker of this disease.

Sex differences exist in adult heart group 2 innate lymphoid cells.

BACKGROUND: Group 2 innate lymphoid cells (ILC2s) are the most dominant ILCs in heart tissue, and sex-related differences exist in mouse lung ILC2 phenotypes and functions; however, it is still unclear whether there are sex differences in heart ILC2s. RESULTS: Compared with age-matched wild-type (WT) male mice, 8-week-old but not 3-week-old WT female mice harbored an obviously greater percentage and number of heart ILC2s in homeostasis. However, the percentage of killer-cell lectin-like receptor G1 (Klrg1)- ILC2s was higher, but the Klrg1+ ILC2s were lower in female mice than in male mice in both heart tissues of 3- and 8-week-old mice. Eight-week-old Rag2-/- mice also showed sex differences similar to those of age-matched WT mice. Regarding surface marker expression, compared to age-matched male mice, WT female mice showed higher expression of CD90.2 and Ki67 and lower expression of Klrg1 and Sca-1 in heart total ILC2s. There was no sex difference in IL-4 and IL-5 secretion by male and female mouse heart ILC2s. Increased IL-33 mRNA levels within the heart tissues were also found in female mice compared with male mice. By reanalyzing published single-cell RNA sequencing data, we found 2 differentially expressed genes between female and male mouse heart ILC2s. Gene set variation analysis revealed that the glycine, serine and threonine metabolism pathway was upregulated in female heart ILC2s. Subcluster analysis revealed that one cluster of heart ILC2s with relatively lower expression of Semaphorin 4a and thioredoxin interacting protein but higher expression of hypoxia-inducible lipid droplet-associated. CONCLUSIONS: These results revealed greater numbers of ILC2s, higher expression of CD90.2, reduced Klrg1 and Sca-1 expression in the hearts of female mice than in male mice and no sex difference in IL-4 and IL-5 production in male and female mouse heart ILC2s. These sex differences in heart ILC2s might be due to the heterogeneity of IL-33 within the heart tissue.

KLMab-1: An Anti-human KLRG1 Monoclonal Antibody for Immunocytochemistry.

Immune checkpoint molecules have received attention as targets of cancer immunotherapy. Killer cell lectin-like receptor subfamily G member 1 (KLRG1) is one of the immune checkpoint molecules expressed in CD4+ T, CD8+ T, and natural killer (NK) cells. KLRG1 exhibits antiviral and antitumor immunity, and its expression in T and NK cells is upregulated by viral infectious diseases and some tumors. Thus, monoclonal antibodies (mAbs) for KLRG1 would be useful tools for the diagnosis and immunotherapy against viral infectious diseases and cancers. We have developed anti-human KLRG1 (hKLRG1) mAb (clone KLMab-1, mouse IgG1, kappa) by the Cell-Based Immunization and Screening method. We have also demonstrated that KLMab-1 recognizes both exogenous and endogenous hKLRG1 in flow cytometry. In this study, we first showed that KLMab-1 and its recombinant mAb (recKLMab-1) bound to exogenous hKLRG1 overexpressed in Chinese hamster ovary (CHO)-K1 cells, but not in parental CHO-K1 cells, in immunocytochemistry. We next showed that both mAbs detected endogenous hKLRG1 expressed in human NK cells. These results demonstrate that KLMab-1 and recKLMab-1 are available for immunocytochemistry.

Immunohistochemical Phenotype of T Cells Invading Muscle in Inclusion Body Myositis.

Inclusion body myositis (IBM) is an inflammatory myopathy of aged people with poor response to therapy. To characterize muscle-invading inflammatory cells, we performed immunohistochemical and ultrastructural studies on muscle biopsies from 10 patients with IBM with durations of illness from 3 to 84 months. At the surface of muscle fibers, 79% and 48% of CD8+ cells were positive for killer cell lectin-like receptor subfamily G, member 1 (KLRG1) and CD57, respectively. CD8+KLRG1+ cells are highly differentiated cytotoxic cells. On an average, 27% of CD8-CD57+KLRG1+ cells at the surface were CD4+. Proportions of CD28+ cells among KLRG1+ cells showed a negative correlation with duration of illness (r = -0.68). These changes indicated progressive differentiation of CD8+ T cells. Moreover, PD-1 expression on CD57+ and CD8+ cells increased early, then fluctuated, and reincreased in later stages. PD ligand-1 (PD-L1) and PD-L2 were expressed on adjacent cells including muscle fibers. T cell large granular lymphocytes (LGLs) are potent effector cells and cells with ultrastructure indistinguishable from LGLs were seen in the sarcoplasm along with lymphocytes undergoing degeneration. Together, along the course of IBM, some inflammatory cells retained the potential for cytotoxicity whereas others indicated suppression by exhaustion, senescence, or through the PD-1 pathway.

Evaluating the diversity of circulating natural killer cells between active tuberculosis and latent tuberculosis infection.

Tuberculosis (TB) is a leading global public health problem; however, the mechanisms underlying the immunopathology of TB progression are not well understood. It is currently believed that Mycobacterium tuberculosis (Mtb) infection can modify natural killer (NK) cell phenotypic signatures. Hence, our study was designed to investigate the diversity of circulating NK cells in patients with different TB infection status. NK subsets, as well as their expression of activating and inhibitory receptors between active TB (ATB) and latent TB infection (LTBI) were evaluated. There were significant differences in NK cell phenotypes between ATB, LTBI and healthy controls. Notably, the proportion of KLRG1 in NK cells (P = 0.036), as well as in their subsets CD56DimCD16+ (P = 0.046) and CD27+ (P = 0.027) NK cells, increased significantly in LTBI group than in ATB group; while Mtb specific IFN-γ+CD56BrightCD16Dim NK cells expressed higher KLRG1 in ATB than in LTBI (P = 0.027). However, the expression of activating receptor NKG2D in NK subsets showed no significant difference among the study groups. Our results suggest that different TB infection status are coupled with the diversity of NK cell compartments, and the expression of KLRG1 in NK cells may be a specific phenotype that modulates the progression of TB from latent to active.

Changes in the expression of T-cell factor-1 in follicular helper T cells reflect the condition of systemic lupus erythematosus patients.

OBJECTIVE: This study aimed to identify changes in T-cell factor-1 (TCF1) in circulating T-cell subsets of systemic lupus erythematosus (SLE) patients and to explore their significance in SLE. METHODS: Peripheral blood was collected from 41 SLE patients and 45 healthy controls (HCs). TCF1 in follicular helper T (TFH), follicular regulatory T (TFR) and regulatory T (Treg) cells was analyzed by flow cytometry. Interleukin-21 (IL-21), programmed death receptor 1 (PD-1) and killer cell lectin-like receptor G1 (KLRG1) were detected and compared among TFH subsets sorted according to TCF1 and CD62L expression. Correlation analyses were conducted between TCF1-related TFH cell subsets and autoantibody levels, systemic lupus erythematosus disease activity index (SLEDAI), and plasmablast levels of SLE patients. RESULTS: Absolute numbers of TCF1- TFH and TCF1+ Treg cells were increased in SLE patients. According to TCF1 and CD62L expression, circulating TFH cells and Tregs were sorted into four subsets. CD62L+TCF1+ TFH cell percentages were decreased, and CD62L-TCF1- TFH cells were increased. CD62L+TCF1+ Treg cell percentages were increased, and CD62L-TCF1- Treg cell percentages were decreased. KLRG1+ percentages in CD62L-TCF1-TFH were higher in SLE patients than in HCs. Functionally, CD62L+TCF1+ TFH cells had stronger IL-21 secretion, while CD62L-TCF1-TFH cells had weaker IL-21 secretion and lower PD-1 expression. TCF1- and CD62L-TCF1- TFH numbers were positively correlated with anti-ribosomal P, anti-dsDNA and SLEDAI. CONCLUSION: The increased TFH cells in SLE patients were mostly TCF1-negative subsets with weakened function. Changes in TCF1-related subsets can reflect the condition and abnormal humoral immunity of SLE patients.

The Yin and Yang of Targeting KLRG1+ Tregs and Effector Cells.

The literature surrounding KLRG1 has primarily focused on NK and CD8+ T cells. However, there is evidence that the most suppressive Tregs express KLRG1. Until now, the role of KLRG1 on Tregs has been mostly overlooked and remains to be elucidated. Here we review the current literature on KLRG1 with an emphasis on the KLRG1+ Treg subset role during cancer development and autoimmunity. KLRG1 has been recently proposed as a new checkpoint inhibitor target, but these studies focused on the effects of KLRG1 blockade on effector cells. We propose that when designing anti-tumor therapies targeting KLRG1, the effects on both effector cells and Tregs will have to be considered.

Increased expression of TIGIT and KLRG1 correlates with impaired CD56bright NK cell immunity in HPV16-related cervical intraepithelial neoplasia.

BACKGROUND: The onset and progression of cervical intraepithelial neoplasia (CIN) are closely associated with the persistent infection of high-risk HPV (especially type16), which is mainly caused by immune escape. Natural killer (NK) cells play an important role against virally infected cells and tumor cells through a fine balance of signals from multiple surface receptors. Overexpression of non-MHC-I specific inhibitory receptors TIGIT, KLRG1, Siglec-7, LAIR-1, and CD300a on NK cells correlates with cellular exhaustion and immune evasion, but these receptors have not been investigated in CIN. The aim of the present study was to examine the potential role of NK cell non-MHC-I specific inhibitory receptors expression in immune escape from HPV16(+)CIN patients. METHODS: The subset distribution, IFN-γ and TNF-α expression levels and immunophenotype of TIGIT, KLRG1, Siglec-7, LAIR-1, and CD300a of NK cells were investigated in peripheral blood mononuclear cell samples by flow cytometry from 82 women who were HPV16(+) with CIN grades 0, I, II-III or HPV(-) CIN 0. Immunohistochemistry was applied to detect the expression of ligands for NK receptors in the cervical tissues. HPV types were identified by PCR assays. RESULTS: The HPV16(+) subjects with high-grade lesions had an increased number of circulating peripheral blood CD56bright NK cells with reduced functionality and IFN-γ secretion. The expression levels of the inhibitory molecules TIGIT and KLRG1 on CD56bright NK cells increased in parallel with increasing CIN grade. In addition, TIGIT and KLRG1 related ligands, Poliovirus receptor (PVR), N-Cadherin and E-Cadherin expression level was also elevated with increasing CIN grade. CONCLUSIONS: Our results suggest that up-regulation of the inhibitory TIGIT, KLRG1 and their ligands may negatively regulate cervical CD56bright NK-mediated immunity to HPV16 and contribute to the progression of CIN. These results may facilitate the development of early-warning immune predictors and therapeutic strategies for HPV16(+) CIN based on the TIGIT and KLRG1 inhibitory pathways of NK cells.

Targeting androgen signaling in ILC2s protects from IL-33-driven lung inflammation, independently of KLRG1.

BACKGROUND: Allergic asthma is more severe and frequent in women than in men. In male mice, androgens negatively control group 2 innate lymphoid cell (ILC2) development and function by yet unknown mechanisms. OBJECTIVES: We sought to investigate the impact of androgen on ILC2 homeostasis and IL-33-mediated inflammation in female lungs. We evaluated the role of androgen receptor (AR) signaling and the contribution of the putative inhibitory receptor killer cell lectin-like receptor G1 (KLRG1). METHODS: Subcutaneous pellets mimicking physiological levels of androgen were used to treat female mice together with mice expressing a reporter enzyme under the control of androgen response elements and mixed bone marrow chimeras to assess the cell-intrinsic role of AR activation within ILC2s. We generated KLRG1-deficient mice. RESULTS: We established that lung ILC2s express a functionally active AR that can be in vivo targeted with exogenous androgens to negatively control ILC2 homeostasis, proliferation, and function. Androgen signaling upregulated KLRG1 on ILC2s, which inhibited their proliferation on E-cadherin interaction. Despite evidence that KLRG1 impaired the competitive fitness of lung ILC2s during inflammation, KLRG1 deficiency neither alters in vivo ILC2 numbers and functions, nor did it lead to hyperactive ILC2s in either sexes. CONCLUSIONS: AR agonists can be used in vivo to inhibit ILC2 homeostatic numbers and ILC2-dependent lung inflammation through cell-intrinsic AR activation. Although androgen signals in ILC2s to upregulate KLRG1, we demonstrate that KLRG1 is dispensable for androgen-mediated inhibition of pulmonary ILC2s.

Expression and Clinical Significance of KLRG1 and 2B4 on T Cells in the Peripheral Blood and Tumour of Patients with Cervical Cancer.

BACKGROUND: Killer cell lectin-like receptor G1 (KLRG1) and 2B4 play important roles in the immune regulation and immune tolerance to tumor cells by inhibiting T cell function. However, the clinical relevance of KLRG1 and 2B4 to cervical cancer remains to be understood. METHODS: We measured the frequency of KLRG1+ or 2B4+ cells in CD4+ or CD8 + T cells derived from peripheral blood or tumour biopsies in cervical cancer patients by flow cytometry. RESULTS: Compared with healthy controls, the level of KLRG1 and 2B4 on CD8 + T cells in the blood of the patients increased significantly (P = .0056 and .0441). KLRG1 level on CD8 + T cells and 2B4 level on CD4 + T cells in peripheral blood were significantly higher than in tumor tissues (P < .0001 and P = .0003). Higher KLRG1 level on blood-derived CD8 + T cells was observed in patients older than 54 years (P = .001) or tested to be HPV-negative (P = .026). Tumor-infiltrated CD8 + T cells demonstrated elevated KLRG1 level in patients having pelvic lymph node metastasis (P = .016). Increased 2B4 level on blood-derived CD8 + T cells was also observed in patients older than 54 years (P < .001). KLRG1 expression on both CD4 + T (P = .0158) and CD8 + T (P = .0187) cells in the peripheral blood increased after radiotherapy. CONCLUSION: KLRG1 level on T cells was related to age and HPV in patients with cervical cancer, while 2B4 level on T cells was related to age, underlying their roles in the host immune response to cervical cancer. Radiotherapy can improve the immune function of patients.