gammadelta T lymphocytes in the peripheral blood of patients with tuberculosis with and without HIV co-infection

BCG vaccination induces innate immune memory in γδ T cells in humans

Bacillus Calmette-Guérin vaccine is well known for inducing trained immunity in myeloid and natural killer cells, which can explain its cross-protective effect against heterologous infections. Although displaying functional characteristics of both adaptive and innate immunity, γδ T-cell memory has been only addressed in a pathogen-specific context. In this study, we aimed to determine whether human γδ T cells can mount trained immunity and therefore contribute to the cross-protective effect of the Bacillus Calmette-Guérin vaccine. We investigated in vivo induction of innate memory in γδ T cells by Bacillus Calmette-Guérin vaccination in healthy human volunteers by combining single-cell RNA sequencing technology with immune functional assays. The total number of γδ T cells and membrane markers of activation was not influenced by Bacillus Calmette-Guérin vaccination. In contrast, Bacillus Calmette-Guérin changed γδ T cells' transcriptional programs and increased their responsiveness to heterologous bacterial and fungal stimuli, including lipopolysaccharide and Candida albicans, as simultaneously characterized by higher tumor necrosis factor and interferon γ production, weeks after vaccination. Human γδ T cells in adults display the potential to develop a trained immunity phenotype after Bacillus Calmette-Guérin vaccination.

Phenotype and function of peripheral blood γδ T cells in HIV infection with tuberculosis

Background

Although γδ T cells play an essential role in immunity against Human Immunodeficiency Virus (HIV) or Mycobacterium tuberculosis (MTB), they are poorly described in HIV infection with tuberculosis (TB).

Methods

The phenotypic and functional properties of peripheral blood γδ T cells in patients with HIV/TB co-infection were analyzed compared to healthy controls and patients with HIV mono-infection or TB by direct intracellular cytokine staining (ICS).

Results

The percentage of Vδ₁ subset in HIV/TB group was significantly higher than that in TB group, while the decreased frequency of the Vδ₂ and Vγ₂Vδ₂ subsets were observed in HIV/TB group than in TB group. The percentage of CD4⁺CD8^- Vδ₂ subset in HIV/TB group was markedly lower than in TB group. However, the percentage of CD4⁺CD8⁺ Vδ₂ subset in HIV/TB group was markedly higher than HIV group or TB group. A lower percentage TNF-α and a higher percentage of IL-17A of Vδ₂ subset were observed in HIV/TB group than that in HIV mono-infection. The percentage of perforin-producing Vδ₂ subset was significantly lower in HIV/TB group than that in HIV group and TB group.

Conclusions

Our data suggested that HIV/TB co-infection altered the balance of γδ T cell subsets. The influence of HIV/TB co-infection on the function of γδ T cells to produce cytokines was complicated, which will shed light on further investigations on the mechanisms of the immune response against HIV and/or MTB infection.

High Activation of γδ T Cells and the γδ2pos T-Cell Subset Is Associated With the Onset of Tuberculosis-Associated Immune Reconstitution Inflammatory Syndrome, ANRS 12153 CAPRI NK

Background: Human Immunodeficiency Virus 1 (HIV-1) and Mycobacterium Tuberculosis (Mtb) co-infected patients are commonly at risk of immune reconstitution inflammatory syndrome (IRIS) when initiating antiretroviral treatment (ART). Evidence indicates that innate immunity plays a role in TB-IRIS. Here, we evaluate the phenotype of Gamma-delta (γδ) T cells and invariant Natural Killer (iNK) T cells in tuberculosis-associated IRIS.

Methods: Forty-eight HIV+/TB+ patients (21 IRIS) and three control groups: HIV–/TB– (HD, n = 11), HIV+/TB– (n = 26), and HIV–/TB+ (n = 22) were studied. Samples were taken at ART initiation (week 2 of anti-tuberculosis treatment) and at the diagnosis of IRIS for HIV+/TB+; before ART for HIV+/TB-, and at week 2 of anti-tuberculosis treatment for HIV–/TB+ patients. γδ T cells and Invariant natural killer T (iNKT) cells were analyzed by flow cytometry.

Results: Before ART, IRIS, and non-IRIS patients showed a similar proportion of γδ^pos T and iNKT cells. HLA-DR on γδ^pos T cells and δ2^posγδ^pos T cells was significantly higher in TB-IRIS vs. non-IRIS patients and controls (p < 0.0001). NKG2D expression on γδ^pos T cells and the δ2^posγδ^pos T cell subset was lower in HIV+/TB+ patients than controls. CD158a expression on γδ^pos T cells was higher in TB-IRIS than non-IRIS (p = 0.02), HIV+/TB–, and HIV–/TB- patients.

Conclusion: The higher activation of γδ^posT cells and the γδ2^posγδ^pos T cell subset suggests that γδ T cells may play a role in the pathogenesis of TB-IRIS.

Phenotypic and functional heterogeneity of peripheral γδ T cells in pulmonary TB and HIV patients in Addis Ababa, Ethiopia

Background

Previous studies reported HIV infection alters the distribution and function of γδ T cells and their subsets. γδ T phenotypes in healthy and diseased individuals has received little attention in Ethiopia. We conducted this study to analyze the distribution of γδ T cells, the subsets and levels of expression of activation (CD38), exhaustion or anergy (CD95, PD1), adhesion (N-CAM/CD56 and CD103), among HIV and TB infected patients.

Method

The distributions of total γδ T cells, Vδ1 and Vδ2 T cells subsets were analyzed in clinical samples collected from asymptomatic HIV, pulmonary TB patients and apparently healthy controls. Multicolor flow cytometry and IFN-γ ELISA were used to assess surface markers and functional responses of Vδ2 T cells to isopentenyl pyrophosphate stimulation, respectively.

Result

A total of 52 study participants were enrolled in this study, 22 HIV + TB-, 10 HIV-TB+ and 20 healthy controls. No significant differences were observed in the distribution of total γδ T cells and in the proportion of Vδ1 subsets in all study groups, though slightly higher proportions were observed in HIV + TB- patients for the latter, of borderline statistical significance (p = 0.07). However, the proportion of Vδ2 T cells, as well as the IFN-γ response to IPP stimulation, was significantly reduced in HIV + TB- patients compared to healthy controls (p < 0.002). Expression of the activation marker CD38 (p < 0.001) and adhesion marker CD103 (αEβ7) were significantly higher in the Vδ1 T cell subset among both HIV + TB- (p = 0.013) and HIV-TB+ (p = 0.006) patients compared to healthy controls. Similarly, exhaustion markers, CD95 and PD1, were significantly higher in these two T cell subsets among both HIV + TB- and HIV-TB+ patients (p < 0.01). Interestingly, we also observed an increased proportion of effector memory (CD45RA-CD27-) and effector cytotoxic (CD45RA + CD27-) Vδ2 T cell subsets in HIV negative pulmonary TB patients.

Conclusion

In sum, HIV infection was associated with an increase in Vδ1 and a decrease in the function and frequencies of Vδ2 T cells. Moreover, increased effector Vδ2 T cells were observed among HIV negative pulmonary TB patients suggesting a potential role of these T cells in the host response to TB.

Comparison of immune peripheral blood cells in tuberculin reactor cattle that are seropositive or seronegative for Mycobacterium bovis antigens

Bovine tuberculosis (bTB) is a major economic problem in animal husbandry and is a public health risk in nonindustrialized countries. It is generally accepted that protection against TB is generated through cell-mediated immunity. Previous investigations have shown that WC1(+) γδ, CD4(+) and CD8(+) T-cell subpopulations are important in the immune response to bTB. It is known that changes in the immune balance from a dominant T helper 1 (Th1)-type response toward a more prominent Th2 response may be observed during disease progression. In this study, we aimed to investigate immune peripheral blood cells in tuberculin reactor cattle that are seropositive or seronegative for Mycobacterium bovis antigens, using flow cytometry and hematological analysis. The evaluation of the T cell subpopulations revealed a decrease in CD8(+) T cells of the seropositive and seronegative animals compared with the control animals (p=0.0001). Moreover, the seropositive group exhibited a lower percentage of CD8(+) T cells than the seronegative group. The percentage of B cells was significantly increased in the seropositive group compared with the seronegative group and the control group (p=0.0009). No difference was observed in the percentage of WC1(+) γδ and CD4(+) T cells among the groups. Furthermore, following 24h of peripheral blood culture with bovine purified protein derivative (PPD), both apparently infected groups showed an increase in the levels of cellular activation compared with the control group (p<0.0001). The seropositive group displayed a higher level of cellular activation than the seronegative group. In both apparently infected groups, the hematological analysis showed an increase in total leukocyte (p=0.0012), lymphocyte (p=0.0057), monocyte (p=0.0010) and neutrophil (p=0.0320) counts in comparison with the healthy animals. Our results demonstrated differences in immune peripheral blood cells of tuberculin reactor cattle that are seropositive or seronegative for M. bovis antigens, probably due to different stages of bTB among the groups. The percentages of CD8(+) T cells, B cells and the T cell activation levels may represent biomarkers for the progression of the disease. However, general characteristics shared by both apparently infected groups as lymphocytosis and monocytosis may also be indicative of the disease. Further experiments are required to understand the variations between cellular and humoral immunities throughout the course of bTB infection. A detailed knowledge of the peripheral blood cells involved in all stages of the bTB immune response of naturally infected cattle is essential for the optimal exploitation of diagnosis and vaccination models.

Expression of regulatory receptors on γδ T cells and their cytokine production in Behcet's disease

INTRODUCTION

Behcet's disease (BD) is a multi-systemic disorder with muco-cutaneous, ocular, arthritic, vascular or central nervous system involvement. The role of γδ T cells is implicated in BD. The activation status of γδ T cells and their cytokine secretion against phosphoantigens are evaluated in BD.

METHODS

NKG2A, NKG2C, NKG2D, CD16 and CCR7 molecules on γδ T cells were analyzed in 70 BD, 27 tuberculosis (TB) patients and 26 healthy controls (HC). Peripheral γδ T cells were expanded with a phosphoantigen (BrHPP) and IL-2, restimulated with BrHPP and a TLR3 ligand, and cytokine production was measured.

RESULTS

γδ T cells were not increased in both BD and TB patients, but the proportions of TCRVδ2+ T cells were lower (58.9 and 50.7 vs. 71.7%, P=0.04 and P=0.005) compared to HC. Higher proportion of TCRVδ2+ T cells were CD16+ (26.2 and 33.9 vs. 16.6%, P=0.02 and P=0.001) and CCR7- (32.2 and 27.9 vs. 17.7%, P<0.0001 and P=0.014) in BD and TB patients compared to HC. NKG2C+ γδ+ T cells were relatively increased (0.5 and 0.6 vs. 0.3%, P=0.008 and 0.018), whereas NKG2D positivity was decreased in patients with BD and TB (77.7 and 75.8 vs. 87.5%, P=0.001 and 0.004). Expansion capacity of γδ T cells in BD and TB as well as production of IL-13, IFN-γ, granulocyte monocyte colony stimulating factor (GM-CSF), TNF-α, CCL4 and CCL5 in BD was lower compared to HC, when restimulated by TLR3 ligand and BrHPP.

CONCLUSION

The changes on γδ T cells of BD as well as TB patients implicate that γδ T cells have already been exposed to regulatory effects, which changed their activity. Lower cytokine response of γδ T cells implicates down modulation of these cells in BD.

Changes in lymphocyte subsets in the peripheral blood of patients with active pulmonary tuberculosis

The aim of this study was to determine the percentage of lymphocyte subsets in peripheral blood in patients with active tuberculosis. A total of 21 patients with active tuberculosis and 15 healthy volunteers were included in the study. T-lymphocyte subsets, B-lymphocytes (CD19(+) cells), natural killer (NK) cells and cells positive for costimulatory molecules CD28 and CD152 were evaluated using flow cytometry. Patients with tuberculosis had a significantly decreased percentage of CD3(+) and CD3(+)CD4(+) cells, and a significantly decreased ratio of CD3(+)CD4(+) to CD3(+)CD8(+) cells compared with healthy controls. In contrast, the percentage of B-cells (CD19(+) cells), CD3(+)CD8(+) cells, CD28(+) cells, CD152(+) cells, and subpopulations of CD4(+)CD152(+), CD8(+)CD152(+) and CD8(+)CD28(+) T-cells were all significantly increased compared with healthy controls. There were no statistically significant differences in the percentages of NK cells or CD4(+)CD28(+) cells between patients and controls. These results indicate that patients with active tuberculosis have altered lymphocyte homeostasis.

Tuberculosis-associated immune restoration syndrome in HIV-1-infected patients involves tuberculin-specific CD4 Th1 cells and KIR-negative gammadelta T cells

Tuberculosis (TB)-associated immune restoration syndrome (IRS) is a frequent event (10 to 30%) in HIV-1-infected patients receiving antiretroviral treatment and is associated with an increased number of IFN-gamma-producing tuberculin-specific cells. To further understand the immune mechanisms of TB-IRS and to identify predictive factors, we prospectively analyzed the Th1 and TCRgammadelta T cells known to be involved in mycobacterial defenses and dendritic cells at baseline and after antiretroviral and TB treatment in 24 HIV-1(+) patients, 11 with and 13 without IRS. At baseline, these two groups differed by significantly lower proportions of TCRgammadelta and Vdelta2(+) T cells displaying the inhibitory receptors CD94/NKG2 and CD158ah,b in IRS patients. The two groups did not differ in the baseline characteristics of CD8 or CD4 T cells or TLR-2 expression on monocytes or myeloid/plasmacytoid dendritic cells. During IRS, the increase in tuberculin-specific IFN-gamma-producing cells involved only highly activated effector memory multifunctional (IFN-gamma(+)TNF-alpha(+)IL-2(-)) CD4 T cells, whereas activated HLA-DR(+) CD4(+) T cells also increased during IRS. In contrast, dendritic cells decreased significantly during IRS and there were no changes in TLR-2 expression. Finally, the Vdelta2(+) T cells, mostly killer Ig-related receptor (KIR) (CD94/NKG2(-) and CD158(-)), significantly peaked during IRS but not in non-IRS patients. In conclusion, IRS is associated with an increase in the number of activated tuberculin-specific effector memory CD4 T cells and of KIR(-)Vdelta2(+) TCRgammadelta(+) T cells. Higher proportions of Vdelta2(+)TCRgammadelta(+) T cells lacking KIR expression are present as baseline and distinguish patients who will develop IRS from those who will not.

Lymphocyte subpopulations in pulmonary tuberculosis patients

Protection against Mycobacterium tuberculosis is based on cell-mediated immunity, most importantly involving CD4⁺ and CD8⁺ T-cell subsets. The aim of this study was to evaluate CD4⁺ and CD8⁺ T-cell profiles and CD19⁺ and CD3⁻CD(16+56)⁺ populations in patients with pulmonary tuberculosis. CD4⁺ and CD8⁺ T cells, B-lymphocytes, and natural killer (NK) cells were evaluated in 75 active (APTB) and 25 inactive (IPTB) pulmonary tuberculosis cases and 20 healthy subjects (HCs). The results were compared at different stages of antituberculosis treatment in the APTB patients and also according to X-ray findings in the newly diagnosed APTB patients. The percentages of CD4⁺ T cells were significantly lower (P < .01) and those of CD3⁻CD(16 + 56)⁺ cells were significantly higher (P < .01) in APTB patients than in HCs. CD8⁺ T cells were significantly decreased (P < .05), and CD3⁻CD(16+56)⁺ cells were significantly increased (P < .01), in IPTB patients compared to HCs. The percentages of CD4⁺, CD8⁺, CD3⁻CD19⁺, and CD3⁻CD(16+56)⁺ cells showed no differences at different times of the antituberculosis regimen, and different stages of newly diagnosed APTB patients. APTB patients have a reduced percentage of circulating CD4⁺ T cells and an increased percentage of NK cells compared with healthy individuals. These cells could play important roles in the immune response to M tuberculosis infection.

Vdelta2+ gammadelta T cell function in Mycobacterium tuberculosis- and HIV-1-positive patients in the United States and Uganda: application of a whole-blood assay

BACKGROUND

Vgamma9(+)Vdelta2(+) gammadelta T cells (Vdelta 2(+) T cells) are activated by Mycobacterium tuberculosis and secrete interferon (IFN)-gamma. Vdelta 2(+) T cells recognize phosphoantigens, such as bromohydrin pyrophosphate (BrHPP), and link innate and adaptive immunity.

METHODS

A whole-blood assay was developed that used IFN-gamma secretion in response to BrHPP as a measurement of Vdelta2(+) T cell function.

RESULTS

Peak IFN-gamma levels were detected after stimulating whole blood with BrHPP for 7-9 days. IFN- gamma production in whole blood in response to BrHPP paralleled IFN-gamma production and Vdelta2(+) T cell expansion of peripheral-blood mononuclear cells. The assay was used to evaluate Vdelta2(+) T cell function in subjects in the United States (n = 24) and Uganda (n = 178) who were or were not infected with M. tuberculosis and/or human immunodeficiency virus (HIV) type 1. When 50 micromol/L BrHPP was used, 100% of healthy subjects produced IFN-gamma. The Vdelta2(+) T cell response was independent of the tuberculin skin test response. In Uganda, Vdelta2(+) T cell responses were decreased in patients with tuberculosis (n = 73) compared with responses in household contacts (n = 105). HIV-1-positive household contacts had lower responses than did HIV-1-negative household contacts. HIV-1-positive patients with tuberculosis had the lowest V delta 2(+) T cell responses.

CONCLUSIONS

Tuberculosis and HIV-1 infection are associated with decreased Velta2(+) T cell function. Decreased Vdelta2(+) T cell function may contribute to increased risk for tuberculosis in HIV-1-positive patients.

Immune regulation of gammadelta T cell responses in mycobacterial infections

Antigen-specific gammadelta T cells may play a role in anti-mycobacterial immunity. Studies done in humans and animal models have demonstrated complex patterns of gammadelta T cell immune responses during early mycobacterial infections and chronic tuberculosis. Recent studies have also shown a clinical correlation between major recall expansion of antigen-specific gammadelta T cells and immunity against fatal early mycobacterial diseases. Multiple host and microbial factors can regulate diverse immune responses of phosphoantigen-specific gammadelta T cells during mycobacterial infections.

Vgamma2Vdelta2+ T cells and anti-microbial immune responses

Vgamma2Vdelta2(+) T cells exist only in primates and constitute the majority of circulating human gammadelta T cells. Recent studies have demonstrated that this unique gammadelta T cell subpopulation can be a component of adaptive immune responses and contribute to anti-microbial immunity to infections.