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Fulltext Acquired radioresistance in EMT6 mouse mammary carcinoma cell line is mediated by CTLA-4 and PD-1 through JAK/STAT/PI3K pathway

Sham NFR, Hasani NAH, Hasan N, Karim MKA, Fuad SBSA, Hasbullah HH, et al.

Sci Rep, 2023 Feb 22;13(1):3108.
PMID: 36813833 DOI: 10.1038/s41598-023-29925-x

Cancer recurrence is often associated with the acquisition of radioresistance by cancer tissues due to failure in radiotherapy. The underlying mechanism leading to the development of acquired radioresistance in the EMT6 mouse mammary carcinoma cell line and the potential pathway involved was investigated by comparing differential gene expressions between parental and acquired radioresistance cells. EMT6 cell line was exposed to 2 Gy/per cycle of gamma-ray and the survival fraction between EMT6-treated and parental cells was compared. EMT6RR_MJI (acquired radioresistance) cells was developed after 8 cycles of fractionated irradiation. The development of EMT6RR_MJI cells was confirmed with further irradiation at different doses of gamma-ray, and both the survival fraction and migration rates were measured. Higher survival fraction and migration rates were obtained in EMT6RR_MJI cells after exposure to 4 Gy and 8 Gy gamma-ray irradiations compared to their parental cells. Gene expression between EMT6RR_MJI and parental cells was compared, and 16 genes identified to possess more than tenfold changes were selected and validated using RT-PCR. Out of these genes, 5 were significantly up-regulated i.e., IL-6, PDL-1, AXL, GAS6 and APCDD1. Based on pathway analysis software, the development of acquired radioresistance in EMT6RR_MJI was hypothesized through JAK/STAT/PI3K pathway. Presently, CTLA-4 and PD-1 were determined to be associated with JAK/STAT/PI3K pathway, where both their expressions were significantly increased in EMT6RR_MJI compared to parental cells in the 1st, 4th and 8th cycle of radiation. As a conclusion, the current findings provided a mechanistic platform for the development of acquired radioresistance in EMT6RR_MJI through overexpression of CTLA-4 and PD-1, and novel knowledge on therapeutic targets for recurrent radioresistant cancers.

Matched MeSH terms: Programmed Cell Death 1 Receptor*
Fulltext Complement-Opsonized HIV-1 Alters Cross Talk Between Dendritic Cells and Natural Killer (NK) Cells to Inhibit NK Killing and to Upregulate PD-1, CXCR3, and CCR4 on T Cells

Ellegård R, Khalid M, Svanberg C, Holgersson H, Thorén Y, Wittgren MK, et al.

Front Immunol, 2018;9:899.
PMID: 29760706 DOI: 10.3389/fimmu.2018.00899

Dendritic cells (DCs), natural killer (NK) cells, and T cells play critical roles during primary HIV-1 exposure at the mucosa, where the viral particles become coated with complement fragments and mucosa-associated antibodies. The microenvironment together with subsequent interactions between these cells and HIV at the mucosal site of infection will determine the quality of immune response that ensues adaptive activation. Here, we investigated how complement and immunoglobulin opsonization influences the responses triggered in DCs and NK cells, how this affects their cross talk, and what T cell phenotypes are induced to expand following the interaction. Our results showed that DCs exposed to complement-opsonized HIV (C-HIV) were less mature and had a poor ability to trigger IFN-driven NK cell activation. In addition, when the DCs were exposed to C-HIV, the cytotolytic potentials of both NK cells and CD8 T cells were markedly suppressed. The expression of PD-1 as well as co-expression of negative immune checkpoints TIM-3 and LAG-3 on PD-1 positive cells were increased on both CD4 as well as CD8 T cells upon interaction with and priming by NK-DC cross talk cultures exposed to C-HIV. In addition, stimulation by NK-DC cross talk cultures exposed to C-HIV led to the upregulation of CD38, CXCR3, and CCR4 on T cells. Together, the immune modulation induced during the presence of complement on viral surfaces is likely to favor HIV establishment, dissemination, and viral pathogenesis.

Matched MeSH terms: Programmed Cell Death 1 Receptor/biosynthesis; Programmed Cell Death 1 Receptor/immunology
Fulltext Programmed cell death-ligand, thymidylate synthase and deleted in colorectal carcinoma biomarkers in colorectal carcinoma

Fauzah Abd Ghani, Reena Rehavu Zin, Maha Abdullah, Norhafizah Mohtarrudin, Ebenyi Emeka Onwe

Malaysian Journal of Medicine and Health Sciences, 2019;15(108):16-16.
MyJurnal

Introduction: It is well known that cancer cells evade the immune system with the help of programmed cell death protein 1 (PD-L1) molecule to remain undetected, causing abnormal proliferation of T-cells. PD-L1 expression on the surface of neoplastic cells inhibits cytotoxic T-cell responses which lead to negative regulation of cytokines and proliferation of T-cells. The deleted in colorectal cancer (DCC) gene belongs to the immunoglobulin superfamily. It is a candidate of the tumour suppressor gene by regulating apoptosis. DCC assessment gives an insight into progno-sis in patients with advanced stages of CRC. Thymidylate synthase (TYMS) is a highly conserved enzyme involved in DNA synthesis. TYMS has been an important target for cancer chemotherapy because of its central, rate-limiting role in de novo synthesis of thymidylate. Expression of PD-L1, TYMS and DCC has been demonstrated to confer a prognostic value in CRC but none have been completely validated for patient care. This study aimed to determine the prognostic and predictive potential of PD-L1, TYMS, and DCC biomarkers in CRC. Methods: The expression of these biomarkers was evaluated immunohistochemically in 91 formalin-fixed paraffin-embedded (FFPE) archival tumour samples from patients that underwent surgical resection. Results: There was high expression of DCC in most cases; 84.6% (77/91). TYMS expression at a high level score was 46.2% (42/91) and at low level was 53.8% (49/91). Majority of cases had low PD-L1 expression in 93.4% (86/91) cases and high expression was detected in 6.6% (6/94) of cases. In addition, there was a significant association between TYMS expression with gender (P < 0.05) with distribution of TYMS expression detected at high level was 76.2% in male and 23.8% in female. The Kaplan-Meier survival plot showed mean overall survival in patients with PD-L1 with high expression to be 22 months, which pre-dicts better survival. TYMS low expression showed mean overall survival of 90 which also indicated better survival. DCC high expression showed mean overall survival of 90 which indicated better survival. The correlation between the biomarkers and overall survival were not statistically significant. Conclusion: The results from this study suggest that PD-L1, TYMS and DCC expression could be used as biomarkers to predict treatment outcome in CRC. PD-L1 overexpression predicts patients who could benefit from anti-PD-1 and anti-PD-L1 immunotherapy whilst TYMS low expression predicts patients who could benefit from 5-fluorouracil therapy. DCC high expression tumours predicts a better prognosis and overall survival compared to DCC-negative tumours in advanced CRC.

Matched MeSH terms: Programmed Cell Death 1 Receptor
Fulltext Association between PDCD1 gene polymorphisms and risk of systemic lupus erythematosus in three main ethnic groups of the Malaysian population

Chua KH, Lian LH, Sim XJ, Cheah TE, Lau TP

Int J Mol Sci, 2015;16(5):9794-803.
PMID: 25938972 DOI: 10.3390/ijms16059794

The programmed cell death 1 (PDCD1) gene encodes for the PD-1 (programmed death 1) molecule, which negatively regulates self-reactive T- and B-cells in the maintenance of peripheral tolerance. A previous report had shown the development of lupus-like phenotypes in PD-1-deficient C57BL/6 mice, was suggestive to the role of PDCD1 in predisposing to systemic lupus erythematosus (SLE). Hence, we aimed to investigate the association between PDCD1 and SLE susceptibility in the Malaysian population. A TaqMan-based real-time PCR was employed to screen for PD1.1, PD1.3, PD1.5 and PD1.6 in both SLE and healthy control groups of 200 samples each. The observed frequency for PD1.5C/C genotype was significantly higher in Indian SLE patients and Malay controls (p < 0.01). On the other hand, the PD1.5C/T genotype might predispose the Malays to SLE, but confer a protective effect among the Indians (p < 0.01). The PD1.1, PD1.3 and PD1.6 were, however, not correlated to genetic predisposition of SLE in our Malaysian population. In conclusion, PD1.5 variant was significantly associated to SLE susceptibility in our Malaysian cohort. Our failure in replicating the association between other investigated PDCD1 variants and risk of getting SLE might due to ethnic and geographic variations in the distribution of these genetic variants.

Matched MeSH terms: Programmed Cell Death 1 Receptor/genetics*
Fulltext Persistent infection due to a small-colony variant of Burkholderia pseudomallei leads to PD-1 upregulation on circulating immune cells and mononuclear infiltration in viscera of experimental BALB/c mice

See JX, Chandramathi S, Abdulla MA, Vadivelu J, Shankar EM

PLoS Negl Trop Dis, 2017 Aug;11(8):e0005702.
PMID: 28820897 DOI: 10.1371/journal.pntd.0005702

BACKGROUND: Melioidosis is a neglected tropical disease endemic across South East Asia and Northern Australia. The etiological agent, Burkholderia pseudomallei (B.pseudomallei), is a Gram-negative, rod-shaped, motile bacterium residing in the soil and muddy water across endemic regions of the tropical world. The bacterium is known to cause persistent infections by remaining latent within host cells for prolonged duration. Reactivation of the recrudescent disease often occurs in elders whose immunity wanes. Moreover, recurrence rates in melioidosis patients can be up to ~13% despite appropriate antibiotic therapy, suggestive of bacterial persistence and inefficacy of antibiotic regimens. The mechanisms behind bacterial persistence in the host remain unclear, and hence understanding host immunity during persistent B. pseudomallei infections may help designing potential immunotherapy.
METHODOLOGY/PRINCIPAL FINDINGS: A persistent infection was generated using a small-colony variant (SCV) and a wild-type (WT) B. pseudomallei in BALB/c mice via intranasal administration. Infected mice that survived for >60 days were sacrificed. Lungs, livers, spleens, and peripheral blood mononuclear cells were harvested for experimental investigations. Histopathological changes of organs were observed in the infected mice, suggestive of successful establishment of persistent infections. Moreover, natural killer (NK) cell frequency was increased in SCV- and WT-infected mice. We observed programmed death-1 (PD-1) upregulation on B cells of SCV- and WT-infected mice. Interestingly, PD-1 upregulation was only observed on NK cells and monocytes of SCV-infected mice. In contrast, cytotoxic T-lymphocyte-associated antigen-4 (CTLA-4) downregulation was seen on NK cells of WT-infected mice, and on monocytes of SCV- and WT-infected mice.
CONCLUSIONS/SIGNIFICANCE: The SCV and the WT of B. pseudomallei distinctly upregulated PD-1 expression on B cells, NK cells, and monocytes to dampen host immunity, which likely facilitates bacterial persistence. PD-1/PD-L1 pathway appears to play an important role in the persistence of B. pseudomallei in the host.

Matched MeSH terms: Programmed Cell Death 1 Receptor/analysis*
Fulltext Association of BRCA1- and BRCA2-deficiency with mutation burden, expression of PD-L1/PD-1, immune infiltrates, and T cell-inflamed signature in breast cancer

Wen WX, Leong CO

PLoS One, 2019;14(4):e0215381.
PMID: 31022191 DOI: 10.1371/journal.pone.0215381

Immune checkpoint inhibitors have demonstrated effective anti-tumour response in cancer types with high mutation burden (e.g. melanoma) and in subset of cancers with features of genomic instability (e.g. mismatch-repair deficiency). One possible explanation for this effect is the increased expression of immune checkpoint molecules and pre-existing adaptive immune response in these cancers. Given that BRCA1 and BRCA2 are integral in maintaining genomic integrity, we hypothesise that the inactivation of these genes may give rise to breast cancers with such immunogenic phenotype. Therefore, using two large series of publicly available breast cancer datasets, namely that from The Cancer Genome Atlas and Wellcome Trust Institute, we sought to investigate the association between BRCA1- and BRCA2-deficiency with features of genomic instability, expression of PD-L1 and PD-1, landscape of inferred tumour-infiltrating immune cells, and T-cell inflamed signature in breast cancers. Here, we report that BRCA1 and BRCA2-deficient breast cancers were associated with features of genomic instability including increased mutation burden. Interestingly, BRCA1-, but not BRCA2-, deficient breast cancers were associated with increased expression of PD-L1 and PD-1, higher abundance of tumour-infiltrating immune cells, and enrichment of T cell-inflamed signature. The differences in immunophenotype between BRCA1- and BRCA2-deficient breast cancers can be attributed, in part, to PTEN gene mutation. Therefore, features of genomic instability such as that mediated by BRCA1- and BRCA2- deficiency in breast cancer were necessary, but not always sufficient, for yielding T cell-inflamed tumour microenvironment, and by extension, predicting clinical benefit from immunotherapy.

Matched MeSH terms: Programmed Cell Death 1 Receptor/immunology; Programmed Cell Death 1 Receptor/metabolism
Fulltext Clinical Use of Programmed Cell Death-1 and Its Ligand Expression as Discriminatory and Predictive Markers in Ovarian Cancer

Chatterjee J, Dai W, Aziz NHA, Teo PY, Wahba J, Phelps DL, et al.

Clin Cancer Res, 2017 07 01;23(13):3453-3460.
PMID: 27986748 DOI: 10.1158/1078-0432.CCR-16-2366

Purpose: We aimed to establish whether programmed cell death-1 (PD-1) and programmed cell death ligand 1 (PD-L1) expression, in ovarian cancer tumor tissue and blood, could be used as biomarkers for discrimination of tumor histology and prognosis of ovarian cancer.Experimental Design: Immune cells were separated from blood, ascites, and tumor tissue obtained from women with suspected ovarian cancer and studied for the differential expression of possible immune biomarkers using flow cytometry. PD-L1 expression on tumor-associated inflammatory cells was assessed by immunohistochemistry and tissue microarray. Plasma soluble PD-L1 was measured using sandwich ELISA. The relationships among immune markers were explored using hierarchical cluster analyses.Results: Biomarkers from the discovery cohort that associated with PD-L1+ cells were found. PD-L1+ CD14+ cells and PD-L1+ CD11c+ cells in the monocyte gate showed a distinct expression pattern when comparing benign tumors and epithelial ovarian cancers (EOCs)-confirmed in the validation cohort. Receiver operating characteristic curves showed PD-L1+ and PD-L1+ CD14+ cells in the monocyte gate performed better than the well-established tumor marker CA-125 alone. Plasma soluble PD-L1 was elevated in patients with EOC compared with healthy women and patients with benign ovarian tumors. Low total PD-1+ expression on lymphocytes was associated with improved survival.Conclusions: Differential expression of immunological markers relating to the PD-1/PD-L1 pathway in blood can be used as potential diagnostic and prognostic markers in EOC. These data have implications for the development and trial of anti-PD-1/PD-L1 therapy in ovarian cancer. Clin Cancer Res; 23(13); 3453-60. ©2016 AACR.

Matched MeSH terms: Programmed Cell Death 1 Receptor/blood*
Fulltext Experimental exposure of Burkholderia pseudomallei crude culture filtrate upregulates PD-1 on T lymphocytes

Menon N, Mariappan V, Vellasamy KM, Samudi C, See JX, Ganesh PS, et al.

Access Microbiol, 2020;2(5):acmi000110.
PMID: 32974575 DOI: 10.1099/acmi.0.000110

Burkholderia pseudomallei is the causative agent for melioidosis. Because of its intracellular nature, the bacterium is capable of replicating within a plethora of eukaryotic cell lines. B. pseudomallei can remain dormant within host cells without symptoms for years, causing recrudescent infections. Here, we investigated the pathogenesis mechanism behind the suppression of T cell responses by B. pseudomallei . Peripheral blood mononuclear cells (1×106 cells/well) isolated by Ficoll Paque (Sigma-Aldrich) density gradient centrifugation were incubated with optimized concentrations of bacterial crude culture filtrate antigens (CFAs) (10 ug ml-1) and heat-killed bacteria [1 : 10 multiplicity of infection (m.o.i.)]. Following incubation, cells were investigated for surface expression of coinhibitory molecules by flow cytometry. We found that B. pseudomallei induced the upregulation of programmed death 1 (PD-1), a molecule responsible for T cell exhaustion, on T cells in vitro following exposure to crude CFAs of B. pseudomallei . This upregulation of PD-1 probably contributes to poor immune surveillance and disease pathogenesis.

Matched MeSH terms: Programmed Cell Death 1 Receptor
Fulltext A meta-analysis on immune checkpoint inhibitor efficacy for advanced non-small cell lung cancer between East Asians versus non-East Asians

Peng S, Ying AF, Tai BC, Soo RA

Transl Lung Cancer Res, 2020 Aug;9(4):1124-1137.
PMID: 32953491 DOI: 10.21037/tlcr-20-246

Background: We conducted a meta-analysis to assess the efficacy of immune checkpoint inhibitors (ICIs) (PD-1/L1 and CTLA-4 inhibitors) in first and subsequent lines in East Asians and non-East Asians.
Methods: We searched PubMed-MEDLINE, Embase and Scopus, from inception to 20 Sep 2019, and reviewed major conferences' abstracts, for randomised controlled trials of ICI in advanced-stage NSCLC (Stage IIIB or IV) without EGFR mutation that reported hazard ratios (HRs) stratified by geographical region including the region "Asia" or "East Asia". The primary outcome measures were overall survival (OS) and progression-free survival (PFS). The pooled HR and its 95% confidence interval (CI) for OS and PFS in East Asians and non-East Asians were calculated using a random effect model and the difference compared using an interaction test.
Results: A total of 5,465 patients from 7 randomised controlled trials involving CTLA-4 and/or PD-1/L1 inhibitors were included, with 1,740 (32%) East Asians and 3,725 (68%) non-East Asians. ICI was associated with an improvement in OS and PFS for both East Asian (OS HR, 0.74; 95% CI, 0.65-0.85; PFS HR, 0.56; 95% CI, 0.40-0.79) and non-East Asian patients (OS HR, 0.78; 95% CI, 0.72-0.85; PFS HR, 0.69; 95% CI, 0.56-0.85), with no significant difference between the two groups (Pinteraction=0.55 for OS; Pinteraction=0.33 for PFS). Subgroup analyses showed a statistically significant superior PFS (but not OS) for East Asians than non-East Asians in trials that used immune checkpoint inhibitor in the first-line treatment (Pinteraction=0.02). No significant regional difference was found in further subgroups of pure ICI and combination of ICI with chemotherapy.
Conclusions: There is no significant difference in response to ICI between East Asians and non-East Asians with advanced stage NSCLC, and the statistically significant subgroup difference in PFS in the first line use of ICI may not be clinically significant.

Matched MeSH terms: Programmed Cell Death 1 Receptor
Fulltext Immune Checkpoint Inhibitors in Urothelial Carcinoma: Recommendations for Practical Approaches to PD-L1 and Other Potential Predictive Biomarker Testing

Lopez-Beltran A, López-Rios F, Montironi R, Wildsmith S, Eckstein M

Cancers (Basel), 2021 Mar 20;13(6).
PMID: 33804698 DOI: 10.3390/cancers13061424

Immuno-oncology (IO) agents (anti-programmed cell death 1 (PD-1) and anti-programmed cell death-ligand 1 (PD-L1)) are approved as first- and second-line treatments for metastatic UC. PD-L1 expression levels in UC tumors help clinicians determine which patients are more likely to respond to IO therapies. Assays for approved IO agents use different antibodies, immunohistochemical protocols, cutoffs (defining "high" vs. "low" PD-L1 expression), and scoring algorithms. The robust control of pre-analytical and analytical standards is needed to obtain high-quality PD-L1 results. To better understand the status and perspectives of biomarker-guided patient selection for anti-PD-1 and anti-PD-L1 agents in UC, three workshops were held from December 2018 to December 2019 in Italy, Malaysia, and Spain. The primary goal was to develop recommendations for best practice approaches to PD-L1 testing in UC. Recommendations pertaining to the interpretation and reporting of the results of PD-L1 assays from experienced pathologists and oncologists from around the globe are included. A test request form for pathology laboratories was developed as a critical first step for oncologists/urologists to encourage communication between clinicians and pathologists, ensuring fast and high-quality test results. In this era of personalized medicine, we briefly discuss novel biomarkers being evaluated for IO agents in UC.

Matched MeSH terms: Programmed Cell Death 1 Receptor
Fulltext Chronic Viral Infection Compromises the Quality of Circulating Mucosal-Associated Invariant T Cells and Follicular T Helper Cells via Expression of Inhibitory Receptors

Vimali J, Yong YK, Murugesan A, Tan HY, Zhang Y, Ashwin R, et al.

Front Biosci (Landmark Ed), 2024 Mar 22;29(3):128.
PMID: 38538288 DOI: 10.31083/j.fbl2903128

BACKGROUND: Chronic viral infection results in impaired immune responses rendering viral persistence. Here, we compared the quality of T-cell responses among chronic hepatitis B virus (HBV), hepatitis C virus (HCV) and human immunodeficiency virus (HIV)-infected individuals by examining the levels of expression of selected immune activation and exhaustion molecules on circulating MAIT cells and Tfh cells.
METHODS: Cytokines were measured using a commercial Bio-plex Pro Human Cytokine Grp I Panel 17-plex kit (BioRad, Hercules, CA, USA). Inflammation was assessed by measuring an array of plasma cytokines, and phenotypic alterations in CD4+ T cells including circulating Tfh cells, CD8+ T cells, and TCR iVα7.2+ MAIT cells in chronic HBV, HCV, and HIV-infected patients and healthy controls. The cells were characterized based on markers pertaining to immune activation (CD69, ICOS, and CD27) proliferation (Ki67), cytokine production (TNF-α, IFN-γ) and exhaustion (PD-1). The cytokine levels and T cell phenotypes together with cell markers were correlated with surrogate markers of disease progression.
RESULTS: The activation marker CD69 was significantly increased in CD4+hi T cells, while CD8+ MAIT cells producing IFN-γ were significantly increased in chronic HBV, HCV and HIV infections. Six cell phenotypes, viz., TNF-α+CD4+lo T cells, CD69+CD8+ T cells, CD69+CD4+ MAIT cells, PD-1+CD4+hi T cells, PD-1+CD8+ T cells, and Ki67+CD4+ MAIT cells, were independently associated with decelerating the plasma viral load (PVL). TNF-α levels showed a positive correlation with increase in cytokine levels and decrease in PVL.
CONCLUSION: Chronic viral infection negatively impacts the quality of peripheral MAIT cells and Tfh cells via differential expression of both activating and inhibitory receptors.

Matched MeSH terms: Programmed Cell Death 1 Receptor
Fulltext Attrition of TCR Vα7.2+ CD161++ MAIT cells in HIV-tuberculosis co-infection is associated with elevated levels of PD-1 expression

Saeidi A, Tien Tien VL, Al-Batran R, Al-Darraji HA, Tan HY, Yong YK, et al.

PLoS One, 2015;10(4):e0124659.
PMID: 25894562 DOI: 10.1371/journal.pone.0124659

Mucosal-associated invariant T (MAIT) cells are evolutionarily conserved antimicrobial MR1-restricted CD8(+) T cells co-expressing the semi-invariant TCR Vα7.2, and are numerous in the blood and mucosal tissues of humans. MAIT cells appear to undergo exhaustion in chronic viral infections. However, their role in human immunodeficiency virus type 1 (HIV-1) mono-infection and HIV/tuberculosis (TB) co-infection have seldom been elaborately investigated. We conducted a cross-sectional study to investigate the frequencies and phenotypes of CD161(++)CD8(+) T cells among anti-retroviral therapy (ART)/anti-TB therapy (ATT) treatment-naïve HIV/TB co-infected, ART/TB treated HIV/TB co-infected, ART naïve HIV-infected, ART-treated HIV-infected patients, and HIV negative healthy controls (HCs) by flow cytometry. Our data revealed that the frequency of MAIT cells was severely depleted in HIV mono- and HIV/TB co-infections. Further, PD-1 expression on MAIT cells was significantly increased in HIV mono- and HIV-TB co-infected patients. The frequency of MAIT cells did not show any significant increase despite the initiation of ART and/or ATT. Majority of the MAIT cells in HCs showed a significant increase in CCR6 expression as compared to HIV/TB co-infections. No marked difference was seen with expressions of chemokine co-receptor CCR5 and CD103 among the study groups. Decrease of CCR6 expression appears to explain why HIV-infected patients display weakened mucosal immune responses.

Matched MeSH terms: Programmed Cell Death 1 Receptor/metabolism*
Increased frequency of late-senescent T cells lacking CD127 in chronic hepatitis C disease

Barathan M, Mohamed R, Saeidi A, Vadivelu J, Chang LY, Gopal K, et al.

Eur J Clin Invest, 2015 May;45(5):466-74.
PMID: 25721991 DOI: 10.1111/eci.12429

Hepatitis C virus (HCV) causes persistent disease in ~85% of infected individuals, where the viral replication appears to be tightly controlled by HCV-specific CD8+ T cells. Accumulation of senescent T cells during infection results in considerable loss of functional HCV-specific immune responses.

Matched MeSH terms: Programmed Cell Death 1 Receptor/immunology
Fulltext Hyper-Expression of PD-1 Is Associated with the Levels of Exhausted and Dysfunctional Phenotypes of Circulating CD161++TCR iVα7.2+ Mucosal-Associated Invariant T Cells in Chronic Hepatitis B Virus Infection

Yong YK, Saeidi A, Tan HY, Rosmawati M, Enström PF, Batran RA, et al.

Front Immunol, 2018;9:472.
PMID: 29616020 DOI: 10.3389/fimmu.2018.00472

Mucosal-associated invariant T (MAIT) cells, defined as CD161++TCR iVα7.2+ T cells, play an important role in the innate defense against bacterial infections, and their functionality is impaired in chronic viral infections. Here, we investigated the frequency and functional role of MAIT cells in chronic hepatitis B virus (HBV) infection. The peripheral CD3+CD161++TCR iVα7.2+ MAIT cells in chronic HBV-infected patients and healthy controls were phenotypically characterized based on CD57, PD-1, TIM-3, and CTLA-4, as well as HLA-DR and CD38 expression. The frequency of MAIT cells was significantly decreased among chronic HBV-infected individuals as compared to controls. Expression of CD57, PD-1, CTLA-4, as well as HLA-DR and CD38 on MAIT cells was significantly elevated in chronic HBV-infected individuals relative to controls. The percentage of T cell receptor (TCR) iVα7.2+ CD161+ MAIT cells did not correlate with HBV viral load but inversely with HLA-DR on CD4+ T cells and MAIT cells and with CD57 on CD8+ T cells suggesting that decrease of MAIT cells may not be attributed to direct infection by HBV but driven by HBV-induced chronic immune activation. The percentage and expression levels of PD-1 as well as CTLA-4 on MAIT cells inversely correlated with plasma HBV-DNA levels, which may suggest either a role for MAIT cells in the control of HBV infection or the effect of HBV replication in the liver on MAIT cell phenotype. We report that decrease of TCR iVα7.2+ MAIT cells in the peripheral blood and their functions were seemingly impaired in chronic HBV-infected patients likely because of the increased expression of PD-1.

Matched MeSH terms: Programmed Cell Death 1 Receptor

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