Reduced T-cell receptor CD3zeta-chain protein and sustained CD3epsilon expression at the site of mycobacterial infection

Exploring modulations in T-cell receptor-mediated T-cell signaling events in systemic circulation and at local disease site of patients with tubercular pleural effusion: An attempt to understand tuberculosis pathogenesis at the local disease site

Introduction

T cells are crucial for pathogenesis as well as control for tuberculosis (TB). Although much is known about the signaling pathways which are required for the activation of T cells during acute infection but the way these cells respond during persistent of infection still remained elusive. Therefore, it is rationale to understand T cell activation during tuberculous pleural effusion (TPE), which is similar to bacterial persistency system.

Methods

Herein, we will employ T cell receptor (TCR) based approaches for studying events of T cell activation pathways in cells of blood and pleural fluid among patients with TPE. We performed spectrofluorimetric analysis to study effect of M. tuberculosis antigens, ESAT-6 and Ag85A stimulation on intracellular calcium levels, Phosphorylation levels of ZAP-70 (Zeta-chain-associated protein kinase 70), PKC-θ (Protein kinase C theta), Erk1/2 (Extracellular signal-regulated kinase 1 and 2) and p-38 two important members of MAPKs (Mitogen activated Protein kinases) in CD3 and CD28 induced cells of blood and pleural fluid of same patients with TPE by western blotting. Patients with non-TPE were also included as matching disease controls in this study.

Results

We observed significantly higher intracellular calcium levels, Phosphorylation levels of ZAP-70, Erk1/2 and p-38 in CD3 and CD28 induced cells of pleural fluid as compared to the blood cells of same patients with TPE. Alteration in the activation of these events has also been noted after stimulation of ESAT-6 and Ag85A.

Discussion

Present study demonstrated up-regulated activation of TCR mediated T cell signaling events at local disease site (Pleural fluid) as compared to the blood sample of TB pleurisy patients which could be involved in T-cell dysfunctioning during the progression of the disease and also could be responsible for Th 1 dominance at local disease site in patients with TPE.

T Cell Interactions in Mycobacterial Granulomas: Non-Specific T Cells Regulate Mycobacteria-Specific T Cells in Granulomatous Lesions

Infections with pathogenic mycobacteria are controlled by the formation of a unique structure known as a granuloma. The granuloma represents a host–pathogen interface where bacteria are killed and confined by the host response, but also where bacteria persist. Previous work has demonstrated that the T cell repertoire is heterogenous even at the single granuloma level. However, further work using pigeon cytochrome C (PCC) epitope-tagged BCG (PCC-BCG) and PCC-specific 5CC7 RAG−/− TCR transgenic (Tg) mice has demonstrated that a monoclonal T cell population is able to control infection. At the chronic stage of infection, granuloma-infiltrating T cells remain highly activated in wild-type mice, while T cells in the monoclonal T cell mice are anergic. We hypothesized that addition of an acutely activated non-specific T cell to the monoclonal T cell system could recapitulate the wild-type phenotype. Here we report that activated non-specific T cells have access to the granuloma and deliver a set of cytokines and chemokines to the lesions. Strikingly, non-specific T cells rescue BCG-specific T cells from anergy and enhance the function of BCG-specific T cells in the granuloma in the chronic phase of infection when bacterial antigen load is low. In addition, we find that these same non-specific T cells have an inhibitory effect on systemic BCG-specific T cells. Taken together, these data suggest that T cells non-specific for granuloma-inducing agents can alter the function of granuloma-specific T cells and have important roles in mycobacterial immunity and other granulomatous disorders.

Temporal Expression of Peripheral Blood Leukocyte Biomarkers in a Macaca fascicularis Infection Model of Tuberculosis; Comparison with Human Datasets and Analysis with Parametric/Non-parametric Tools for Improved Diagnostic Biomarker Identification

A temporal study of gene expression in peripheral blood leukocytes (PBLs) from a Mycobacterium tuberculosis primary, pulmonary challenge model Macaca fascicularis has been conducted. PBL samples were taken prior to challenge and at one, two, four and six weeks post-challenge and labelled, purified RNAs hybridised to Operon Human Genome AROS V4.0 slides. Data analyses revealed a large number of differentially regulated gene entities, which exhibited temporal profiles of expression across the time course study. Further data refinements identified groups of key markers showing group-specific expression patterns, with a substantial reprogramming event evident at the four to six week interval. Selected statistically-significant gene entities from this study and other immune and apoptotic markers were validated using qPCR, which confirmed many of the results obtained using microarray hybridisation. These showed evidence of a step-change in gene expression from an ‘early’ FOS-associated response, to a ‘late’ predominantly type I interferon-driven response, with coincident reduction of expression of other markers. Loss of T-cell-associate marker expression was observed in responsive animals, with concordant elevation of markers which may be associated with a myeloid suppressor cell phenotype e.g. CD163. The animals in the study were of different lineages and these Chinese and Mauritian cynomolgous macaque lines showed clear evidence of differing susceptibilities to Tuberculosis challenge. We determined a number of key differences in response profiles between the groups, particularly in expression of T-cell and apoptotic makers, amongst others. These have provided interesting insights into innate susceptibility related to different host `phenotypes. Using a combination of parametric and non-parametric artificial neural network analyses we have identified key genes and regulatory pathways which may be important in early and adaptive responses to TB. Using comparisons between data outputs of each analytical pipeline and comparisons with previously published Human TB datasets, we have delineated a subset of gene entities which may be of use for biomarker diagnostic test development.

TCR-CD3ζ gene polymorphisms and expression profile in rheumatoid arthritis

OBJECTIVES

Recent evidence has demonstrated that CD3ζ (also called CD247) play a vital role in multiple autoimmune diseases. In this study, we explored the association between CD247 gene single-nucleotide polymorphisms (SNPs) and rheumatoid arthritis (RA) in a Chinese Han population. We also evaluated the CD3ζ expression profile in peripheral blood mononuclear cells (PBMCs) from patients with RA and health controls.

METHODS

Three CD247 polymorphisms (rs704853, rs1214611 and rs858554) were studied in 612 patients with RA and 848 controls in a Chinese population. Genotyping was performed using the Fluidigm 192.24 Dynamic Array™ Integrated Fluidic Circuit (IFC). For gene expression study, CD3ζ mRNA levels of 36 patients with RA and 39 healthy individuals were assessed by real-time polymerase chain reaction (RT-PCR). Data were analyzed by SPSS 11.5 software.

RESULTS

A significant association between rs858554 polymorphism and RA was found under all genetic models (all p < 0.05). Moreover, we found the genotype distribution and allele frequency of rs858554 were significant associated with ACCP⁺ and RF⁺ phenotype as compare to health controls (all p < 0.05). Unfortunately, we did not detect any significant associations between rs704853, rs1214611 and RA susceptibility and autoantibody profiles (all p > 0.05). The gene expression assays showed that CD3ζ mRNA levels were downregulated in PBMCs of patients with RA when compared to healthy controls.

CONCLUSIONS

Our results, the first reported for distinct Chinese populations, support a role of the CD247 gene in the susceptibility to RA. Further studies with more sample size are necessary to clarify the exact role of CD247 gene in the pathogenesis of RA.

Frequency of Mycobacterium tuberculosis-specific CD8+ T-cells in the course of anti-tuberculosis treatment

Anti-tuberculosis drug treatment is known to affect the number, phenotype, and effector functionality of antigen-specific T-cells. In order to objectively gauge Mycobacterium tuberculosis (MTB)-specific CD8+ T-cells at the single-cell level, we developed soluble major histocompatibility complex (MHC) class I multimers/peptide multimers, which allow analysis of antigen-specific T-cells without ex vivo manipulation or functional tests. We constructed 38 MHC class I multimers covering some of the most frequent MHC class I alleles (HLA-A*02:01, A*24:02, A*30:01, A*30:02, A*68:01, B*58:01, and C*07:01) pertinent to a South African or Zambian population, and presenting the following MTB-derived peptides: the early expressed secreted antigens TB10.4 (Rv0288), Ag85B (Rv1886c), and ESAT-6 (Rv3875), as well as intracellular enzymes, i.e., glycosyltransferase 1 (Rv2957), glycosyltransferase 2 (Rv2958c), and cyclopropane fatty acid synthase (Rv0447c). Anti-TB treatment appeared to impact on the frequency of multimer-positive CD8+ T-cells, with a general decrease after 6 months of therapy. Also, a reduction in the total central memory CD8+ T-cell frequencies, as well as the antigen-specific compartment in CD45RA-CCR7+ T-cells was observed. We discuss our findings on the basis of differential dynamics of MTB-specific T-cell frequencies, impact of MTB antigen load on T-cell phenotype, and antigen-specific T-cell responses in tuberculosis.

Mycobacterium tuberculosis secretory proteins downregulate T cell activation by interfering with proximal and downstream T cell signalling events

Background

Mycobacterium tuberculosis (M. tuberculosis) modulates host immune response, mainly T cell responses for its own survival leading to disease or latent infection. The molecules and mechanisms utilized to accomplish immune subversion by M. tuberculosis are not fully understood. Understanding the molecular mechanism of T cell response to M. tuberculosis is important for development of efficacious vaccine against TB.

Methods

Here, we investigated effect of M. tuberculosis antigens Ag85A and ESAT-6 on T cell signalling events in CD3/CD28 induced Peripheral blood mononuclear cells (PBMCs) of PPD+ve healthy individuals and pulmonary TB patients. We studied CD3 induced intracellular calcium mobilization in PBMCs of healthy individuals and TB patients by spectrofluorimetry, CD3 and CD28 induced activation of mitogen activated protein kinases (MAPKs) in PBMCs of healthy individuals and TB patients by western blotting and binding of transcription factors NFAT and NFκB by Electrophorectic mobility shift assay (EMSA).

Results

We observed CD3 triggered modulations in free intracellular calcium concentrations in PPD+ve healthy individuals and pulmonary TB patients after the treatment of M. tuberculosis antigens. As regards the downstream signalling events, phosphorylation of MAPKs, Extracellular signal-regulated kinase 1 and 2 (ERK1/2) and p38 was curtailed by M. tuberculosis antigens in TB patients whereas, in PPD+ve healthy individuals only ERK1/2 phosphorylation was inhibited. Besides, the terminal signalling events like binding of transcription factors NFAT and NFκB was also altered by M. tuberculosis antigens. Altogether, our results suggest that M. tuberculosis antigens, specifically ESAT-6, interfere with TCR/CD28-induced upstream as well as downstream signalling events which might be responsible for defective IL-2 production which further contributed in T-cell unresponsiveness, implicated in the progression of disease.

Conclusion

To the best of our knowledge, this is the first study to investigate effect of Ag85A and ESAT-6 on TCR- and TCR/CD28- induced upstream and downstream signalling events of T-cell activation in TB patients. This study showed the effect of secretory antigens of M. tuberculosis in the modulation of T cell signalling pathways. This inflection is accomplished by altering the proximal and distal events of signalling cascade which could be involved in T-cell dysfunctioning during the progression of the disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12865-015-0128-6) contains supplementary material, which is available to authorized users.

TCR+CD4-CD8- T cells in antigen-specific MHC class I-restricted T-cell responses after allogeneic hematopoietic stem cell transplantation

Human TCRαβ(+) CD4(-)CD8(-) double-negative (DN) T cells represent a minor subset in peripheral blood, yet are important in infectious diseases and autoimmune responses. We examined the frequency of DN T cells in 17 patients after allogeneic hematopoietic stem cell transplantation (aHSCT) at 1, 2, 3, 6, and 12 months post-aHSCT and show that these cells increase early after aHSCT and decrease with time after aHSCT. DN T cells reside in the terminally differentiated effector (CD45RA(+)CCR7(-)) T-cell population and are polyclonal, determined by T-cell receptor Vβ CDR3 analysis. Gene expression analysis of ex vivo sorted DN T cells showed a distinct set of gene expression, including interleukin-8, as compared with CD4(+) or CD8(+) T cells. DN T cells contributed to MHC class I-restricted EBV-directed immune responses, defined by antigen-specific cytokine production and by detection of HLA-A*02:01-restricted EBV BMLF-1 (GLCTLVAML), LMP-2A (CLGGLLTMV), and HLA-A*24:02-restricted EBV BRLF-1 (DYCNVLNKEF) and EBNA3 (RYSIFFDY)-specific T cells. We created retroviral-transfected Jurkat cell lines with a Melan-A/MART-1-specific TCR(+) and the CD8α chain to study TCR(+) DN T cells in response to their nominal MHC class I/peptide ligand. We show that DN T cells exhibit increased TCRζ chain phosphorylation as compared with the TCR(+)CD8(+) transgenic T-cell line. DN T cells contribute to antigen-specific T-cell responses and represent an effector T-cell population that may be explored in immunotherapeutic approaches against viral infections or transformed cells.

Inflammation and tuberculosis: host-directed therapies

Tuberculosis (TB) is an airborne infectious disease that kills almost two million individuals every year. Multidrug-resistant (MDR) TB is caused by strains of Mycobacterium tuberculosis (M. tb) resistant to isoniazid and rifampin, the backbone of first-line antitubercular treatment. MDR TB affects an estimated 500,000 new patients annually. Genetic analysis of drug-resistant MDR-TB showed that airborne transmission of undetected and untreated strains played a major role in disease outbreaks. The need for new TB vaccines and faster diagnostics, as well as the development of new drugs, has recently been highlighted. The major problem in terms of current TB research and clinical demands is the increasing number of cases of extensively drug-resistant and 'treatment-refractory' TB. An emerging scenario of adjunct host-directed therapies is intended to target pulmonary TB where inflammatory processes can be deleterious and lead to immune exhaustion. 'Target-organ-saving' strategies may be warranted to prevent damage to infected tissues and achieve focused, clinically relevant and long-lasting anti-M. tb cellular immune responses. Candidates for such interventions may be biological agents or already approved drugs that can be 're-purposed' to interfere with biologically relevant cellular checkpoints. Here, we review current concepts of inflammation in TB disease and discuss candidate pathways for host-directed therapies to achieve better clinical outcomes.

The risk factors for tuberculosis in liver or kidney transplant recipients

BACKGROUND

Liver or kidney transplant recipients are at a higher risk of developing tuberculosis (TB) than general population. We aimed to clarify the incidence density of and risk factors for TB in liver or kidney transplant recipients in the present study.

METHODS

All patients with TB following liver or kidney transplantation were investigated retrospectively at the Third Xiangya Hospital, Central South University, Changsha, China. The incidence density of TB was calculated. We performed a nested case-control study (1:1) to investigate by univariate and multivariate logistic regression analysis the potential risk factors for TB.

RESULTS

From January 2000 to August 2013, 1748 kidney and 166 liver transplant recipients were performed at a university teaching hospital. Among the 1914 recipients, 45 cases (2.4%) of TB were reported. The incidence density was 506 cases per 105 patient-years in kidney or liver transplant recipients, which was 7 times higher than in the general Chinese population (around 70 cases per 105 person-years). The median time to develop TB was 20.0 months (interquartile ratio: 5.0-70.0). The receipt of a graft from a cadaveric donor (odds ratio [OR] = 3.7; 95% confidence interval [CI] = 1.4-10.0; P = 0.010) and the preoperative evidence of latent TB (OR = 6.8; 95% CI = 2.0-22.7; P = 0.002) were identified as two risk factors for developing TB in liver or kidney transplant recipients.

CONCLUSIONS

The incidence density of TB among liver or kidney transplant recipients was much higher than in the general Chinese population. Recipients receiving a graft from a cadaveric donor and the preoperative evidence of latent TB were two major risk factors for developing TB in liver or kidney transplant recipients.

Autologous mesenchymal stromal cell infusion as adjunct treatment in patients with multidrug and extensively drug-resistant tuberculosis: an open-label phase 1 safety trial

BACKGROUND

Novel treatment options are urgently needed for multidrug-resistant (MDR) and extensively drug-resistant (XDR) tuberculosis, which are associated with immune dysfunction and poor treatment outcomes. Mesenchymal stromal cells (MSCs) are immunomodulatory and adjunct autologous treatment with bone marrow-derived MSCs might improve clinical outcome by transforming chronic inflammation into productive immune responses. Our aim was to assess the safety of infusion of autologous MSCs as an adjunct treatment in patients with tuberculosis.

METHODS

30 patients with microbiologically confirmed MDR or XDR tuberculosis were treated with single-dose autologous bone marrow-derived MSCs (aimed for 1×10(6) cells per kg), within 4 weeks of the start of antituberculosis-drug treatment in a specialist centre in Minsk, Belarus. Inclusion patients were those with pulmonary tuberculosis confirmed by sputum smear microscopy, culture, or both; MDR or XDR tuberculosis confirmed by drug-susceptibility testing to first-line and second-line drugs; age older than 21 years to 65 years or younger; and absence of lesion compatible with a malignant process or ongoing tuberculosis in organs other than the lungs and pleura. In addition to the inclusion criteria, patients were excluded if they were pregnant, coinfected with HIV, or infected with hepatitis B, C, or both. The primary endpoint was safety measured by MSC-infusion related events; any tuberculosis-related event within the 6 month observation period that related to a worsening of the underlying infectious disease, measured by conversion of Mycobacterium tuberculosis culture or microscopic examination; or any adverse event defined clinically or by changes in blood haematology and biochemistry variables, measured monthly for 6 months after MSC infusion per protocol. This study is registered with the German Clinical Trials Registry, number DRKS00000763.

FINDINGS

The most common (grade 1 or 2) adverse events were high cholesterol levels (14 of 30 patients), nausea (11 of 30 patients), and lymphopenia or diarrhoea (ten of 30 patients). There were no serious adverse events reported. We recorded two grade 3 events that were transitory-ie, increased plasma potassium ion concentrations in one patient and a transitory grade 3 γ-glutamyltransferase elevation in another patient.

INTERPRETATION

MSCs as an adjunct therapy are safe and can now be explored further for the treatment of patients with MDR or XDR tuberculosis in combination with standard drug regimens. Adjunct treatment with MSCs needs to be evaluated in controlled phase 2 trials to assess effects on immune responses and clinical and microbiological outcomes.

Human leukocyte antigens A*3001 and A*3002 show distinct peptide-binding patterns of the Mycobacterium tuberculosis protein TB10.4: consequences for immune recognition

High-tuberculosis (TB)-burden countries are located in sub-Saharan Africa. We examined the frequency of human leukocyte antigen (HLA) alleles, followed by recombinant expression of the most frequent HLA-A alleles, i.e., HLA-A*3001 and HLA-A*3002, to study differences in mycobacterial peptide presentation and CD8(+) T-cell recognition. We screened a peptide library (9-mer peptides with an 8-amino-acid overlap) for binding, affinity, and off-rate of the Mycobacterium tuberculosis-associated antigen TB10.4 and identified only three TB10.4 peptides with considerable binding to HLA-A*3001. In contrast, 22 peptides bound to HLA-A*3002. This reflects a marked difference in the binding preference between the two alleles, with A*3002 tolerating a more promiscuous peptide-binding pattern and A*3001 accommodating only a very selective peptide repertoire. Subsequent analysis of the affinity and off-rate of the binding peptides revealed a strong affinity (8 nM to 7 μM) and moderate off-rate (20 min to 3 h) for both alleles. Construction of HLA-A*3001 and HLA-A*3002 tetramers containing selected binding peptides from TB10.4, including a peptide which was shared among both alleles, QIMYNYPAM (TB10.4(3-11)), allowed us to enumerate epitope-specific T cells in HLA-A*3001- and HLA-A*3002-typed patients with active TB. HLA-A*3001 and HLA-A*3002 major histocompatibility complex-peptide complexes were recognized in individuals with active TB, irrespective of their homozygous HLA-A*3001 or HLA-A*3002 genetic background. The antigen-specific T cells exhibited the CD45RA(+) CCR7(+) precursor phenotype and the interleukin-7 receptor (CD127), which were different from the phenotype and receptor exhibited by the parental CD8(+) T-cell population.

Tracking antigen-experienced effector T cells in vitro and in vivo

The TCR complex is a multisubunit complex, comprising at least eight transmembrane units. The clonotypic TCR alpha and beta chains are responsible for antigen recognition, whilst the invariant chains of the CD3 complex (delta, epsilon and gamma) and two zeta (zeta) polypeptides couple antigen recognition to downstream signal transduction pathways. TCRzeta (CD247) functions as an amplification module in the TCR signalling cascade and is also essential for the assembly and surface expression of the TCR/CD3 complex. Loss of TCRzeta expression is common in chronic infectious and inflammatory diseases, as well as in cancer. Previous work has indicated that TCRzeta(low)-expressing cells phenotypically resemble antigen-experienced effector T cells. Here, we describe the derivation of a flow cytometry-based TCRzeta expression index for the purpose of more precisely defining TCRzeta expression, in addition to utilising a simple transmigration assay in the demonstration that TCRzeta(dim) T cells have intrinsic migratory properties that may explain their accumulation at sites of inflammation.

Extensive major histocompatibility complex class I binding promiscuity for Mycobacterium tuberculosis TB10.4 peptides and immune dominance of human leucocyte antigen (HLA)-B*0702 and HLA-B*0801 alleles in TB10.4 CD8 T-cell responses

The molecular definition of major histocompatibility complex (MHC) class I-presented CD8(+) T-cell epitopes from clinically relevant Mycobacterium tuberculosis (Mtb) target proteins will aid in the rational design of T-cell-based diagnostics of tuberculosis (TB) and the measurement of TB vaccine-take. We used an epitope discovery system, based on recombinant MHC class I molecules that cover the most frequent Caucasian alleles [human leucocyte antigen (HLA)-A*0101, A*0201, A*0301, A*1101, A*2402, B*0702, B*0801 and B*1501], to identify MHC class I-binding peptides from overlapping 9-mer peptides representing the Mtb protein TB10.4. A total of 33 MHC class I-binding epitopes were identified, spread across the entire amino acid sequence, with some clustering at the N- and C-termini of the protein. Binding of individual peptides or closely related peptide species to different MHC class I alleles was frequently observed. For instance, the common motif of xIMYNYPAMx bound to six of eight alleles. Affinity (50% effective dose) and off-rate (half life) analysis of candidate Mtb peptides will help to define the conditions for CD8(+) T-cell interaction with their nominal MHC class I-peptide ligands. Subsequent construction of tetramers allowed us to confirm the recognition of some of the epitopes by CD8(+) T cells from patients with active pulmonary TB. HLA-B alleles served as the dominant MHC class I restricting molecules for anti-Mtb TB10.4-specific CD8(+) T-cell responses measured in CD8(+) T cells from patients with pulmonary TB.

Peptide microarray-based identification of Mycobacterium tuberculosis epitope binding to HLA-DRB1*0101, DRB1*1501, and DRB1*0401

A more effective vaccine against Mycobacterium tuberculosis is needed, and a number of M. tuberculosis vaccine candidates are currently in preclinical or clinical phase I and II studies. One of the strategies to select M. tuberculosis (protein) targets to elicit a CD8(+) or CD4(+) T-cell response is to gauge the binding of candidate peptides to major histocompatibility complex (MHC) class I or class II molecules, a prerequisite for successful peptide presentation and to expand antigen-specific T cells. We scanned 61 proteins from the M. tuberculosis proteome for potential MHC class II-presented epitopes that could serve as targets for CD4(+) T-cell responses. We constructed a peptide microarray consisting of 7,466 unique peptides derived from 61 M. tuberculosis proteins. The peptides were 15-mers overlapping by 12 amino acids. Soluble recombinant DRB1*0101 (DR1), DRB1*1501 (DR2), and DRB1*0401 (DR4) monomers were used to gauge binding to individual peptide species. Out of 7,466 peptides, 1,282, 674, and 1,854 peptides formed stable complexes with HLA-DR1, -DR2, and -DR4, respectively. Five hundred forty-four peptides bound to all three MHC class II molecules, 609 bound to only two, and 756 bound to only a single MHC class II molecule. This allowed us to rank M. tuberculosis proteins by epitope density. M. tuberculosis proteins contained "hot spots," i.e., regions with enriched MHC class II binding epitopes. Two hundred twenty-two peptides that formed MHC class II-peptide complexes had previously been described as exclusively recognized by IgG in sera from patients with active pulmonary tuberculosis, but not in sera from healthy individuals, suggesting that these peptides serve as B-cell and CD4(+) T-cell epitopes. This work helps to identify not only M. tuberculosis peptides with immunogenic potential, but also the most immunogenic proteins. This information is useful for vaccine design and the development of future tools to explore immune responses to M. tuberculosis.

Mycobacterium tuberculosis cell wall glycolipids directly inhibit CD4+ T-cell activation by interfering with proximal T-cell-receptor signaling

Immune evasion is required for Mycobacterium tuberculosis to survive in the face of robust adaptive CD4(+) T-cell responses. We have previously shown that M. tuberculosis can indirectly inhibit CD4(+) T cells by suppressing the major histocompatibility complex class II antigen-presenting cell function of macrophages. This study was undertaken to determine if M. tuberculosis could directly inhibit CD4(+) T-cell activation. Murine CD4(+) T cells were purified from spleens by negative immunoaffinity selection followed by flow sorting. Purified CD4(+) T cells were activated for 16 to 48 h with CD3 and CD28 monoclonal antibodies in the presence or absence of M. tuberculosis and its subcellular fractions. CD4(+) T-cell activation was measured by interleukin 2 production, proliferation, and expression of activation markers, all of which were decreased in the presence of M. tuberculosis. Fractionation identified that M. tuberculosis cell wall glycolipids, specifically, phosphatidylinositol mannoside and mannose-capped lipoarabinomannan, were potent inhibitors. Glycolipid-mediated inhibition was not dependent on Toll-like receptor signaling and could be bypassed through stimulation with phorbol 12-myristate 13-acetate and ionomycin. ZAP-70 phosphorylation was decreased in the presence of M. tuberculosis glycolipids, indicating that M. tuberculosis glycolipids directly inhibited CD4(+) T-cell activation by interfering with proximal T-cell-receptor signaling.

The CD3Z 844 T>A polymorphism within the 3'-UTR of CD3Z confers increased risk of incidence of systemic lupus erythematosus

Recently, a family-based association analysis showed that the haplotype carrying a low expression of the variant CD3Z 844 T>A (rs1052231) polymorphism located in the 3'-untranslated region of CD3Z predisposes to systemic lupus erythematosus (SLE) incidence. We analyzed the prevalence of the CD3Z 844 T>A polymorphism in SLE patients (n = 152) and controls (n = 304) in Poland. We observed that women with the CD3Z AA and CD3Z AT genotypes exhibited a 1.845-fold increased risk of SLE [95% confidence intervals (95% CI) = 1.222-2.787, P = 0.0038]. However, we did not find an increased risk for the homozygous CD3Z AA genotype (odds ratio = 1.204, 95% CI = 0.2838-5.108, P = 1.0000). This observation confers that genetic factors causing a decreased level of CD3-zeta in T cells may predispose to SLE incidence.

T cell CD3 receptor zeta (TCRzeta)-chain expression in children with idiopathic nephrotic syndrome

Children with idiopathic nephrotic syndrome (INS) have an increased risk of developing life-threatening infections. Several studies have demonstrated functional abnormalities in the T lymphocytes of patients with nephrotic syndrome. Although T cells are activated in INS during relapse, as indicated by an increased expression of interleukin (IL)-2 receptor, these cells have a decreased ability to proliferate. The T-cell receptor (TCR) plays an important role in signal transduction and T cell activation, with the TCR-zeta (TCRzeta) chain being a key element in early signaling. We measured the expression of the TCRzeta chain in patients with INS (steroid resistant and steroid sensitive) during relapse and remission by flow cytometry and by PCR ELISA. The results showed a significant decrease in the expression of the TCRzeta chain at both the protein and mRNA level in INS patients during relapse as compared with normal controls (p < 0.05). In contrast, when patients with INS achieved remission, the expression of TCRzeta normalized and was similar to that expressed in normal controls. Therefore, a decreased expression of the TCRzeta chain may explain the abnormal function of T cells in patients with INS, and it may also contribute to the increased risk for infections seen in these patients.

Impaired phenotype and function of monocyte derived dendritic cells in pulmonary tuberculosis

Pulmonary tuberculosis (PTB) is often associated with impaired immunological functions. Blood monocytes, which can differentiate into dendritic cells upon cytokine stimulation, play a central role in adequate immune reactivity. Here, we investigated the morphologic, phenotypic and functional characteristics of in vitro-generated monocyte derived dendritic cells (MoDC) from PTB patients in comparison with healthy subjects. Phenotypic analysis revealed a defective differentiation of MoDC in PTB patients as assessed by a strong down regulation of CD1a, MHC II, CD80 and CD83 expression and impaired allostimulatory function under the influence of IL-4 and GM-CSF. In contrast, the expression of CD86 was not affected and remained same as in healthy subjects. Furthermore, the maturation status of lipopolysaccharide (LPS) stimulated MoDC was not optimal in PTB. However, the MoDC of PTB patients produced significantly higher levels of TNF-alpha and IL-6 but lower levels of IL-12 compared to healthy subjects. These findings suggest that there is a fundamental defect in the differentiation and maturation of dendritic cells during PTB that may compromise the antigen presentation and subsequent immune functions.

Polymorphisms in the CD3Z gene influence TCRzeta expression in systemic lupus erythematosus patients and healthy controls

TCRzeta (CD247) functions as an amplification module in the TCR signaling cascade and is essential for assembly and surface expression of the TCR/CD3 complex. The TCRzeta-chain is down-regulated in many chronic infectious and inflammatory diseases, including systemic lupus erythematosus (SLE). It is unclear whether reduced TCRzeta expression is a cause or a consequence of chronic inflammatory responses. We have addressed this question by adopting a combined genetic and functional approach. We analyzed TCRzeta protein expression using a FACS-based expression index and documented considerable, but longitudinally stable, variation in TCRzeta expression in healthy individuals. The variation in TCRzeta expression was associated with polymorphisms in the CD3Z 3'-untranslated region (UTR) in SLE patients and healthy controls. Detailed mapping of the 3'-UTR revealed that the minor alleles of two single nucleotide polymorphisms (SNPs) in strong disequilibrium (rs1052230 and rs1052231) were the causal variants associated with low TCRzeta expression (p=0.015). Using allelic imbalance analysis, the minor alleles of these 3'-UTR SNPs were associated with one-third of the level of mRNA compared with the major allele. A family-based association analysis showed that the haplotype carrying the low-expression variants predisposes to SLE (p=0.033). This suggests that a genetically determined reduction in TCRzeta expression has functional consequences manifested by systemic autoimmunity.

What does the immunogenetic basis of rheumatoid arthritis teach us about the immunobiology of the disease?

Rheumatoid arthritis is a chronic inflammatory autoimmune disease in which, although the exact etiology is unknown, the contribution from genetic factors is approximately 60%. major histocompatibility complex alleles make the largest contribution to this genetic effect. The remainder is probably made up of an, as yet undefined, number of genes ( approximately 50-200) with low disease penetrance. Recent advances in genetic technology are now enabling us to start to identify some of these more moderate risk-conferring candidate genes. Evidence from functional studies of such genes is beginning to provide insight into the exact nature of the pathways and processes involved in disease susceptibility and expression. In this review, we will discuss how a growing number of genetic polymorphisms might underpin the immunological and molecular anomalies characteristic of rheumatoid arthritis. Specifically, we will focus on one particular pathway, T-cell activation, with an emphasis on the genetic polymorphism that influences antigen presentation and recognition in antigen-presenting cells, as well as those genes that influence the thresholds of antigen-receptor signaling in T lymphocytes.

Transcriptional profiling of the peripheral blood response during tularemia

Tularemia is a febrile disease caused by the highly contagious bacterium Francisella tularensis. We undertook an analysis of the transcriptional response in peripheral blood during the course of ulceroglandular tularemia by use of Affymetrix microarrays comprising 14,500 genes. Samples were obtained from seven individuals at five occasions during 2 weeks after the first hospital visit and convalescent samples 3 months later. In total, 265 genes were differentially expressed, 95 of which at more than one time point. The differential expression was verified with real-time quantitative polymerase chain reaction for 36 genes (R(2)=0.590). The most prominent changes were noted in samples drawn on days 2-3 and a considerable proportion of the upregulated genes appeared to represent an interferon-gamma-induced response and also a proapoptotic response. Genes involved in the generation of innate and acquired immune responses were found to be downregulated, presumably a pathogen-induced event. A logistic regression analysis revealed that seven genes were good predictors of the early phase of tularemia. This is the first description of the transcriptional host response to ulceroglandular tularemia and the study has identified gene subsets relevant to the pathogenesis of the disease and subsets that may serve as early diagnostic biomarkers.

Defective CD3γ gene transcription is associated with NFATc2 overexpression in the lymphocytic variant of hypereosinophilic syndrome

OBJECTIVE

Determine the molecular defects underlying the CD3(-)CD4(+) T-cell phenotype and persistence of this clonal population in patients with hypereosinophilic syndrome.

PATIENTS AND METHODS

Patients in this study suffer from the lymphocytic variant of hypereosinophilic syndrome distinguished by a CD3(-)CD4(+) T-cell clone that overexpresses Th2 cytokines upon activation and thereby provokes the eosinophilia. Interleukin-2-dependent CD3(-)CD4(+) T-cell lines were derived from patient blood at various disease stages and used to investigate the molecular modifications correlated with their abnormal phenotype.

RESULTS

We demonstrate that the CD3(-)CD4(+) T cells, characterized by a clonal TCRbeta gene rearrangement, maintained the same immunophenotype over the 6-year period of our study, during which one patient progressed from premalignant disease to CD3(-)CD4(+) T-cell lymphoma. We show that a specific loss of CD3gamma gene transcripts is responsible for the defect in TCR/CD3 surface expression. In addition, the level of NFATc2 binding to NFAT motifs in the CD3gamma gene promoter was greatly increased in the abnormal T cells. Our studies indicate that CD3gamma promoter activity can be positively influenced by NFATc1 plus NF-kappaB p50 and negatively regulated by NFATc2 containing complexes. We show that in patients' CD3(-)CD4(+) T cells, an increase in nuclear NFATc2 occurs in parallel with a decrease in NFATc1 and NF-kappaB gene expression.

CONCLUSION

Hypereosinophilic syndrome joins the growing number of pathological conditions where a defect in surface expression and/or function of the TCR/CD3 complex results from altered regulation of CD3gamma gene expression.

Altered expression of the T cell receptor-CD3 complex in systemic lupus erythematosus

SLE T cells may play a key role in autoantibody production in SLE B cells. In addition, accumulating evidence has shown that SLE T cells participate in the attack on target cells or tissues through the overproduction of pro-inflammatory cytokines or an increase in cell-to-cell adhesion. Thus, the functional abnormality of SLE T cells appears to be pivotal to an understanding of SLE pathogenesis. Accumulating evidence suggests that potential defects may reside in the proximal signal transduction around the TCR-CD3 complex. We have demonstrated that the expression of TCR zeta chain is significantly decreased in peripheral blood T cells from SLE patients. To explore the mechanism of defective expression of TCR zeta chain, we examined mRNA of TCR zeta, and found that two alternatively spliced variants such as exon 7 (-) and short 3'-UTR are detected in SLE. We review the possible role of the TCR zeta defects in autoimmunity and discuss how the splicing variants lead to downregulated protein expression of TCR zeta chain.

Characterization of effusion-infiltrating T cells: benign versus malignant effusions

PURPOSE

While naïve T cells circulate between peripheral blood and lymph nodes, memory effector T cells acquire certain surface molecules that enable them to travel to peripheral tissues and exert their effector function. We analyzed whether deficient numbers of effector-type T cells within the malignant effusion might contribute to tumor escape from immunosurveillance.

EXPERIMENTAL DESIGN

We analyzed the expression of a broad range of adhesion molecules and chemokine receptors (CD62L, CD56, CCR4, CCR5, CCR7, CXCR3, CLA, and integrin alpha 4 beta 7) on tumor-associated lymphocytes in effusions and peripheral blood lymphocytes of patients with malignant ascites (n = 11) or malignant pleural effusion (n = 16). A tumor-associated lymphocyte:peripheral blood lymphocyte ratio was calculated as an indicator for homing of lymphocytes into the effusions and was compared with patients with nonmalignant ascites (n = 17).

RESULTS

Patients with malignancies show an increased enrichment of T cells expressing the phenotype of "naïve" (CD62L+ and CD45RA+CCR7+), "central memory" (CD45RA-CCR7+), and type 2-polarized (CCR4+) T cells within their effusions. In contrast, enrichment of "effector"-type (CD45RA-CCR7- or CD45RA+CCR7-) and presumably type 1-polarized T cells (CCR5+) at the tumor site is deficient. The same is true for natural killer cells and potentially cytotoxic CD56+ T cells.

CONCLUSIONS

Here we show for the first time that patients with malignant effusions show a deficient enrichment of T cells expressing the phenotype of type-1-polarized effector T cells at the tumor site. This mechanism is likely to contribute to the escape of tumor cells from immunosurveillance.

Mycobacterial granulomas: keys to a long-lasting host-pathogen relationship

Chronic infection with mycobacteria is controlled by the formation of granulomas. The failure of granuloma maintenance results in reactivation of disease. Macrophages are the dominant cell type in granulomas, but CD4+ T cells are the master organizers of granuloma structure and function. Recent work points to an unrecognized role for nonspecific T cells in maintaining granuloma function in the chronic phase of infection. In addition, it has become clear that mycobacteria and host T cells collaborate in formation of granulomas. Further understanding of how nonspecific T cells contribute to granuloma formation, as well as how bacteria and T cells maintain a harmonious relationship over the life of the host, will facilitate the development of new strategies to treat mycobacterial disease.

TCR zeta-chain downregulation: curtailing an excessive inflammatory immune response

The T-cell receptor (TCR) functions in both antigen recognition and signal transduction, which are crucial initial steps of antigen-specific immune responses. TCR integrity is vital for the induction of optimal and efficient immune responses, including the routine elimination of invading pathogens and the elimination of modified cells and molecules. Of the TCR subunits, the zeta-chain has a key role in receptor assembly, expression and signalling. Downregulation of TCR zeta-chain expression and impairment of T-cell function have been shown for T cells isolated from hosts with various chronic pathologies, including cancer, and autoimmune and infectious diseases. This review summarizes studies of the various pathologies that show this phenomenon and provides new insights into the mechanism responsible for downregulation of zeta-chain expression, its relevance and its clinical implications.

Helicobacter pylori arginase inhibits T cell proliferation and reduces the expression of the TCR zeta-chain (CD3zeta)

Helicobacter pylori infects approximately half the human population. The outcomes of the infection range from gastritis to gastric cancer and appear to be associated with the immunity to H. pylori. Patients developing nonatrophic gastritis present a Th1 response without developing protective immunity, suggesting that this bacterium may have mechanisms to evade the immune response of the host. Several H. pylori proteins can impair macrophage and T cell function in vitro through mechanisms that are poorly understood. We tested the effect of H. pylori extracts and live H. pylori on Jurkat cells and freshly isolated human normal T lymphocytes to identify possible mechanisms by which the bacteria might impair T cell function. Jurkat cells or activated T lymphocytes cultured with an H. pylori sonicate had a reduced proliferation that was not caused by T cell apoptosis or impairment in the early T cell signaling events. Instead, both the H. pylori sonicate and live H. pylori induced a decreased expression of the CD3zeta-chain of the TCR. Coculture of live H. pylori with T cells demonstrated that the wild-type strain, but not the arginase mutant rocF(-), depleted L-arginine and caused a decrease in CD3zeta expression. Furthermore, arginase inhibitors reversed these events. These results suggest that H. pylori arginase is not only important for urea production, but may also impair T cell function during infection.

HIV, 'an evolving species'. Roles of cellular activation and co-infections

Each small variation of the genome of a species can be preserved if it is useful for the survival of the species in a given environment. Within this framework, the finality of the biological cycle of HIV consists in a search for harmony (biological coherence) with man, which is to say a stable condition. Cellular activation appears to be the strategy developed by HIV in order to achieve this coherence. The price of this strategy is the AIDS. The first contact between HIV and immune system appears to determine the subsequent clinical outcome and the future of HIV. Lymphocytic activation varies during the course of the vital cycle of HIV. For each individual, this lymphocytic activation depends on both the HLA repertoire acquired during thymic ontogenesis and the antigenic experience before and after HIV infection. Thus intercurrent infections alter the immune condition of the organism and influence the outcome of HIV. We described a synthetic analysis of the effects of HIV on the surface protein expression and the cellular activation pathways which should provide insights in the evolutionary relationship between HIV and man and should permit to do a more physiological therapeutic approach.

Definition of the HLA-A2 restricted peptides recognized by human CD8+ effector T cells by flow-assisted sorting of the CD8+ CD45RA+ CD28- T cell subpopulation

In response to antigenic stimulation, naive MHC-class I restricted and antigen-specific CD8+ CD45RA+ CD28+ T cells undergo clonal expansion, differentiate into CD8+ CD45RO+ memory T cells and convert to CD8+ CD45RA+ CD28- T cells displaying potent immune effector functions upon re-encounter with the nominal antigen. We show that the effector CD8+ CD45RA+ CD28- T cell subset is expanded in peripheral blood lymphocytes (PBL) from patients with human papilloma virus (HPV)+ cervical lesions as well as in PBL from patients with pulmonary tuberculosis. Flow-cytometric cell sorted CD8+ CD45RA+ CD28- and CD8+ CD45RA+ CD28- T cells were tested for recognition of HLA-A2 restricted peptides derived either from the human papillomavirus (HPV)16-E7 gene product, or from M. tuberculosis antigens. Mostly CD8+ CD45+ CD28- T cells define antigen/peptide-specific and MHC-restricted responses. These data were confirmed in PBL from patients with tuberculosis using HLA-A2 tetramer-complexes loaded with a peptide from the M. tuberculosis Ag85b antigen by flow cytometry. The sorting of this T cell subset enables to determine the fine specificity of CD8+ effector T cells without the need for in vitro manipulation.

Defective production of functional 98-kDa form of Elf-1 is responsible for the decreased expression of TCR zeta-chain in patients with systemic lupus erythematosus

Systemic lupus erythematosus (SLE), the prototypic autoimmune disease, is characterized by defective expression of TCR zeta-chain. Elf-1 (E-74-like factor) is a member of the Ets (E-26-specific) family and is crucial for the basal transcription of TCR zeta-chain in Jurkat cells. We previously demonstrated that Elf-1 exists in the cytoplasm mainly as 80-kDa form and after phosphorylation and O-glycosylation it moves to the nucleus as a 98-kDa which binds DNA. We now demonstrate that Elf-1 is crucial for the transactivation of TCR zeta-chain promoter in normal and SLE T cells. Defective expression of TCR zeta-chain in SLE T cells is associated with two distinct molecular defects in the generation of the 98-kDa DNA binding Elf-1 form. In the first, the levels of the 98-kDa form were either decreased or absent. In the second, the apparent levels of the nuclear Elf-1 form were normal but included only two of the three bands into which the nuclear Elf-1 form separated in isoelectric focusing gels. Because both the transcription and the translation processes of Elf-1 gene are normal in SLE T cells, our data demonstrate that abnormal posttranslational mechanisms of the Elf-1 protein result in defective expression of functional Elf-1, and consequently, the transcriptional defect of TCR zeta-chain in patients of SLE.