PD-1/PD-Ls pathways between CD4(+) T cells and pleural mesothelial cells in human tuberculous pleurisy

Characterization of multiple soluble immune checkpoints in individuals with different Mycobacterium tuberculosis infection status and dynamic changes during anti-tuberculosis treatment

BACKGROUND

Immune checkpoints are crucial for the maintenance of subtle balance between self-tolerance and effector immune responses, but the role of soluble immune checkpoints (sICs) in Mycobacterium tuberculosis (M. tb) infection remains unknown. We assessed the levels of multiple sICs in individuals with distinct M. tb infection status, and their dynamic changes during anti-tuberculosis treatment.

METHODS

We enrolled 24 patients with pulmonary tuberculosis, among which 10 patients were diagnosed with tuberculous pleurisy (TBP), 10 individuals with latent tuberculosis infection (LTBI), and 10 healthy volunteers from Wuxi Fifth People's Hospital and Huashan Hospital between February 2019 and May 2021. Plasma concentrations of thirteen sICs were measured at enrollment and during anti-tuberculosis treatment using luminex-based multiplex assay. sICs levels in tuberculous pleural effusion (TPE) and their relations to laboratory test markers of TPE were also assessed in TBP patients.

RESULTS

The circulating levels of sPD-1, sPD-L1, sCTLA-4, sBTLA, sGITR, sIDO, sCD28, sCD27 and s4-1BB were upregulated in tuberculosis patients than in healthy controls. A lower sPD-L1 level was found in LTBI individuals than in tuberculosis patients. In TBP patients, the levels of sPD-1, sPD-L2, sCD28, sCD80, sCD27, sTIM-3, sLAG-3, sBTLA, s4-1BB and sIDO increased significantly in TPE than in plasma. In TPE, sBTLA and sLAG-3 correlated positively with the adenosine deaminase level. sIDO and sCD80 correlated positively with the lactate dehydrogenase level and the percentage of lymphocytes in TPE, respectively. Meanwhile, sCD27 correlated negatively with the specific gravity and protein level in TPE. In tuberculosis patients, the circulating levels of sBTLA and sPD-L1 gradually declined during anti-tuberculosis treatment.

CONCLUSIONS

We characterized the changing balance of sICs in M. tb infection. And our results revealed the relations of sICs to laboratory test markers and treatment responses in tuberculosis patients, indicating that certain sICs may serve as potential biomarkers for disease surveillance and prognosis of tuberculosis.

Downregulation of the PD-1/PD-Ls pathway in peripheral cells correlates with asbestosis severity

Background

Asbestosis and silicosis are characterized by diffuse or nodular interstitial lung fibrosis resulting from exposure to asbestos or silica dust, respectively. This study was designed to detect programmed cell death protein (PD-1)/programmed death ligands (PD-Ls) expression in patients with asbestosis and silicosis and to explore the possible clinical significance of PD-1/PD-Ls expression in patients with the two diseases.

Methods

Thirty patients with asbestosis, 23 patients with silicosis and 25 healthy controls were consecutively recruited and provided informed consent to participate in the study. Clinical data were collected from patients’ clinical charts. PD-1/PD-Ls expression in peripheral blood (PB) was detected using flow cytometry.

Results

PD-1 was expressed at significantly lower levels on CD4⁺ or CD8⁺ peripheral T cells from patients with asbestosis and silicosis than on cells from healthy controls. Similarly, significantly lower PD-L1 and PD-L2 expression was detected on CD14⁺ monocytes from patients with asbestosis and silicosis than on cells from healthy controls. In addition, no significant differences in PD-1, PD-L1 and PD-L2 expression were observed between the asbestosis and silicosis groups. Moreover, the proportions of PD-1⁺ CD4⁺ T cells and PD-1⁺ CD8⁺ T cells in patients with asbestosis were positively correlated with the percentage of forced vital capacity predicted.

Conclusions

Decreased PD-1 expression on CD4⁺ T or CD8⁺ T cells in PB was positively correlated with the asbestosis severity, implying that pulmonary fibrosis development in patients with asbestosis was positively correlated with the downregulation of the PD-1/PD-Ls pathway.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-021-01531-5.

Diagnostic Usefulness of Cytokine and Chemokine Levels in the Cerebrospinal Fluid of Patients with Suspected Tuberculous Meningitis

In this study, we investigated the diagnostic utility of the cytokine profile of the cerebrospinal fluid (CSF) and enzyme-linked immunospot (ELISPOT) assays of patients with suspected tuberculous meningitis (TBM). We prospectively enrolled adult patients with suspected TBM, and CSF specimens were analyzed for 18 cytokines/chemokines and soluble programmed death protein 1 (PD-1) and programmed death ligand 1 (PD-L1). Enzyme-linked immunospot assays were performed on mononuclear cells from the CSF (CSF-MCs) and peripheral blood (PBMCs). A total of 87 patients with meningitis, including 42 TBM-suspected patients and 45 non-TBM patients, were enrolled. Excluding the 32 patients with possible TBM, 10 patients with TBM and 45 patients with non-TBM were finally analyzed. Levels of adenosine deaminase (ADA), interleukin 12 subunit β (IL-12p40), IL-13, macrophage inflammatory protein α (MIP-1α), and soluble PD-1 and PD-L1 in the CSF were significantly higher in the TBM group than in the non-TBM group (P < 0.05). The optimal cutoff values for the sensitivities and specificities of the test methods for diagnosing TBM with small samples of 10 cases of definite or probable TBM were as follows: ADA > 6.95 U/L, 70% and 81%; IL-12p40 > 52.04 pg/mL, 80% and 73%; IL-13 > 0.44 pg/mL, 90% and 47%; MIP-1α > 8.83 pg/mL, 80% and 62%; soluble PD-1 > 35.87 pg/mL, 80% and 63%; soluble PD-L1 > 24.19 pg/mL, 80% and 61%; CSF-MC ELISPOT > 13.5 spots/250,000 CSF-MC, 30% and 91%; and PBMC ELISPOT > 14 spots/250,000 PBMCs, 50% and 78%, respectively. Therefore, CSF IL-12p40, IL-13, MIP-1α, and soluble PD-1 and PD-L1 concentrations appear to be useful adjuncts for diagnosing TBM.

PD-1-expressing MAIT cells from patients with tuberculosis exhibit elevated production of CXCL13

To understand functional role of PD-1-expressing MAIT cells during tuberculosis infection in humans, sorted PD-1⁺ and PD-1^- MAIT cells from pleural effusions of patients with pleural tuberculosis were subjected to transcriptome sequencing. PD-1-expressing MAIT cells were analysed by flow cytometry and their phenotypic and functional features were investigated. Transcriptome sequencing identified 144 genes that were differentially expressed between PD-1⁺ and PD-1^- MAIT cells from tuberculous pleural effusions and CXCL13 was the gene with highest fold difference. The level of PD-1-expressing MAIT cells was associated with extent of TB infection in humans. PD-1-expressing MAIT cells had increased production of CXCL13 and IL-21 as determined by flow cytometry. PD-1^high CXCR5^- MAIT cells were significantly expanded in pleural effusions from patients with pleural tuberculosis as compared with those from peripheral blood of both patients with tuberculosis and healthy controls. Although PD-1^high CXCR5^- MAIT cells from tuberculous pleural effusions had reduced IFN-γ level and increased expression of Tim-3 and GITR, they showed activated phenotype and had higher glucose uptake and lipid content. It is concluded that PD-1-expressing MAIT cells had reduced IFN-γ level but increased production of both CXCL13 and IL-21.

Meta-analysis of human gene expression in response to Mycobacterium tuberculosis infection reveals potential therapeutic targets

Background

With the global emergence of multi-drug resistant strains of Mycobacterium tuberculosis, new strategies to treat tuberculosis are urgently needed such as therapeutics targeting potential human host factors.

Results

Here we performed a statistical meta-analysis of human gene expression in response to both latent and active pulmonary tuberculosis infections from nine published datasets. We found 1655 genes that were significantly differentially expressed during active tuberculosis infection. In contrast, no gene was significant for latent tuberculosis. Pathway enrichment analysis identified 90 significant canonical human pathways, including several pathways more commonly related to non-infectious diseases such as the LRRK2 pathway in Parkinson’s disease, and PD-1/PD-L1 signaling pathway important for new immuno-oncology therapies. The analysis of human genome-wide association studies datasets revealed tuberculosis-associated genetic variants proximal to several genes in major histocompatibility complex for antigen presentation. We propose several new targets and drug-repurposing opportunities including intravenous immunoglobulin, ion-channel blockers and cancer immuno-therapeutics for development as combination therapeutics with anti-mycobacterial agents.

Conclusions

Our meta-analysis provides novel insights into host genes and pathways important for tuberculosis and brings forth potential drug repurposing opportunities for host-directed therapies.

Electronic supplementary material

The online version of this article (doi: 10.1186/s12918-017-0524-z) contains supplementary material, which is available to authorized users.

The PD-L1/PD-1 pathway promotes dysfunction, but not "exhaustion", in tumor-responding T cells from pleural effusions in lung cancer patients

Malignant pleural effusions are frequent in patients with advanced stages of lung cancer and are commonly infiltrated by lymphocytes and tumor cells. CD8+ T cells from these effusions have reduced effector functions. The programmed death receptor 1(PD-1)/programmed death ligand 1 (PD-L1) pathway is involved in T-cell exhaustion, and it might be responsible for T-cell dysfunction in lung cancer patients. Here, we show that PD-L1 is expressed on tumor cell samples from malignant effusions, on lung cancer cell lines, and, interestingly, on MRC-5 lung fibroblasts. PD-L1 was up-regulated in lung cancer cell lines upon treatment with IFN-gamma, but not under hypoxic conditions, as detected by RT-qPCR and flow cytometry. Blockade of PD-L1 on tumor cells restored granzyme-B expression in allogenic CD8+ T cells in vitro. Remarkably, pleural effusion CD8+ T cells that responded to the tumor antigens MAGE-3A and WT-1 (identified as CD137+ cells) were lower in frequency than CMV pp65-responding CD8+ T cells and did not have an exhausted phenotype (PD-1+ TIM-3+). Nonetheless, tumor-responding CD8+ T cells had a memory phenotype and expressed higher levels of PD-1. A PD-L1 blocking antibody increased the expression of granzyme-B and perforin on polyclonal- and tumor-stimulated CD8+ T cells. Taken together, our data show that rather than being exhausted, tumor-responding CD8+ T cells are not completely differentiated into effector cells and are prone to negative regulation by PD-L1. Hence, our study provides evidence that lung cancer patients respond to immunotherapy due to blockade of the PD-L1/PD-1 pathway.

Programmed death-1+ T cells inhibit effector T cells at the pathological site of miliary tuberculosis

Optimal T cell activation is vital for the successful resolution of microbial infections. Programmed death-1 (PD-1) is a key immune check-point receptor expressed by activated T cells. Aberrant/excessive inhibition mediated by PD-1 may impair host immunity to Mycobacterium tuberculosis infection, leading to disseminated disease such as miliary tuberculosis (MTB). PD-1 mediated inhibition of T cells in pulmonary tuberculosis and TB pleurisy is reported. However, their role in MTB, particularly at the pathological site, remains to be addressed. The objective of this study was to investigate the role of PD-1-PD-ligand 1 (PD-L1) in T cell responses at the pathological site from patients of TB pleurisy and MTB as clinical models of contained and disseminated forms of tuberculosis, respectively. We examined the expression and function of PD-1 and its ligands (PD-L1-PD-L2) on host immune cells among tuberculosis patients. Bronchoalveolar lavage-derived CD3 T cells in MTB expressed PD-1 (54·2 ± 27·4%, P ≥ 0·0009) with significantly higher PD-1 ligand-positive T cells (PD-L1: 19·8 ± 11·8%; P ≥ 0·019, PD-L2: 12·6 ± 6·2%; P ≥ 0·023), CD19⁺ B cells (PD-L1: 14·4 ± 10·4%; P ≥ 0·042, PD-L2: 2·6 ± 1·43%; not significant) and CD14⁺ monocytes (PD-L1: 40·2 ± 20·1%; P ≥ 0·047, PD-L2: 22·4 ± 15·6%; P ≥ 0·032) compared with peripheral blood (PB) of MTB and healthy controls. The expression of PD-1 was associated with a diminished number of cells producing effector cytokines interferon (IFN)-γ, tumour necrosis factor (TNF)-α, interleukin (IL)-2 and elevated apoptosis. Locally accumulated T cells were predominantly PD-1⁺ -PD-L1⁺ , and blocking this pathway restores the protective T cell response. We conclude that M. tuberculosis exploits the PD-1 pathway to evade the host immune response by altering the T helper type 1 (Th1) and Th2 balance at the pathological site of MTB, thereby favouring disease dissemination.

PD-1/PD-L pathway inhibits M.tb-specific CD4+ T-cell functions and phagocytosis of macrophages in active tuberculosis

The role of the PD-1/PD-L pathway in a murine model of tuberculosis remains controversial regarding viral infections and clinical tuberculosis. We conducted a case-control study to investigate the modulating role and mechanism of the PD-1/PD-L pathway in patients with active tuberculosis. Fifty-nine participants, including 43 active tuberculosis (ATB) patients and 16 healthy controls (HC), were enrolled. Cell surface staining and flow cytometry were used to detect the expressions of PD-1 and its ligands on T cells and monocytes. Intracellular cytokine staining was used to determine the PPD-specific IFN-γ-secreting T-cell proportion. CD4⁺ T-cell proliferation and macrophage functions were investigated in the presence or absence of PD-1/PD-L pathway blockade. Proportions of both PD-1⁺CD4⁺ and PD-L1⁺CD4⁺ T cells in ATB patients were more significantly increased than in the HC group (P = 0.0112 and P = 0.0141, respectively). The expressions of PD-1, PD-L1, and PD-L2 on CD14⁺ monocytes in ATB patients were much higher than those in the HC group (P = 0.0016, P = 0.0001, and P = 0.0088, respectively). Blockade of PD-1 could significantly enhance CD4⁺ T-cell proliferation (P = 0.0433). Phagocytosis and intracellular killing activity of macrophages increased significantly with PD-1/PD-L pathway blockade. In conclusion, the PD-1/PD-L pathway inhibits not only M.tb-specific CD4⁺ T-cell-mediated immunity but also innate immunity.

Increased soluble and membrane-bound PD-L1 contributes to immune regulation and disease progression in patients with tuberculous pleural effusion

Soluble and membrane-bound programmed death ligand-1 (sPD-L1 and mPD-L1, respectively) have been demonstrated to participate in the immune suppression of non-small cell lung cancer. However, the contribution of sPD-L1 and mPD-L1 to immune regulation and disease progression in patients with pleural effusions remains unknown. The present study evaluated the levels of sPD-L1 and membrane-bound PD-1/PD-L1 in the peripheral blood and pleural effusions of patients with tuberculous pleural effusion (TPE), malignant pleural effusion (MPE) and non-tuberculous non-malignant pleural effusion (n-TB n-M). Furthermore, selected T lymphocytes and cluster of differentiation (CD)14⁺ monocytes were co-cultured to investigate the potential effect of the PD-1/PD-L1 pathway in TPE. Levels of sPD-L1 and PD-L1 on CD14⁺ monocytes were increased in the TPE group, as compared with the MPE and n-TB n-M groups. Furthermore, sPD-L1 levels and the expression levels of PD-L1 on CD14⁺ monocytes were demonstrated to be positively correlated with interferon (IFN)-γ concentration in pleural effusions. Therefore, IFN-γ may increase the expression of PD-L1 on CD14⁺ monocytes in vitro. Cell counting kit-8 analysis demonstrated that anti-PD-L1 antibody was able to partially reverse the proliferation of T lymphocytes in the co-culture system. The results of the present study indicated that sPD-L1 or mPD-L1 are associated with the immune regulation and disease progression of TPE, and may serve as possible biomarkers of TPE. Furthermore, sPD-L1 and the PD-1/PD-L1 pathway of TPE may be associated with the Th1 immune response; therefore, an anti-PD-1/PD-L1 pathway suggests a potential immune therapy strategy for the treatment of TPE.