IFN-gamma and IL-12 are increased in active compared with inactive tuberculosis

Multiple cytokine analysis based on QuantiFERON-TB gold plus in different tuberculosis infection status: an exploratory study

BACKGROUND

More efficient and convenient diagnostic method is a desperate need to reduce the burden of tuberculosis (TB). This study explores the multiple cytokines secretion based on QuantiFERON-TB Gold Plus (QFT-Plus), and screens for optimal cytokines with diagnostic potential to differentiate TB infection status.

METHODS

Twenty active tuberculosis (ATB) patients, fifteen patients with latent TB infection (LTBI), ten patients with previous TB and ten healthy controls (HC) were enrolled. Whole blood samples were collected and stimulated by QFT-Plus TB1 and TB2 antigens. The levels of IFN-γ, TNF-α, IL-2, IL-6, IL-5, IL-10, IP-10, IL-1Ra, CXCL-1 and MCP-1 in supernatant were measured by Luminex bead-based multiplex assays. The receiver operating characteristic curve was used to evaluate the diagnostic accuracy of cytokine for distinguishing different TB infection status.

RESULTS

After stimulation with QFT-Plus TB1 and TB2 antigens, the levels of all cytokines, except IL-5 in TB2 tube, in ATB group were significantly higher than that in HC group. The levels of IL-1Ra concurrently showed the equally highest AUC for distinguishing TB infection from HC, followed by the levels of IP-10 in both TB1 tube and TB2 tube. Moreover, IP-10 levels displayed the largest AUC for distinguishing ATB patients from non-ATB patients. Meanwhile, the levels of IP-10 also demonstrated the largest AUC in both TB1 tube and TB2 tube for distinguishing ATB patients from LTBI.

CONCLUSIONS

In addition to conventional detection of IFN-γ, measuring IP-10 and IL-1Ra based on QFT-Plus may have the more tremendous potential to discriminate different TB infection status.

Circular RNAs in tuberculosis: From mechanism of action to potential diagnostic biomarker

Tuberculosis (TB), caused by Mycobacterium tuberculosis (M. tuberculosis), continues to be a major global health concern. Understanding the molecular intricacies of TB pathogenesis is crucial for developing effective diagnostic and therapeutic approaches. Circular RNAs (circRNAs), a class of single-stranded RNA molecules characterized by covalently closed loops, have recently emerged as potential diagnostic biomarkers in various diseases. CircRNAs have been demonstrated to modulate the host's immunological responses against TB, specifically by reducing monocyte apoptosis, augmenting autophagy, and facilitating macrophage polarization. This review comprehensively explores the roles and mechanisms of circRNAs in TB pathogenesis. We also discuss the growing body of evidence supporting their utility as promising diagnostic biomarkers for TB. By bridging the gap between fundamental circRNA biology and TB diagnostics, this review offers insights into the exciting potential of circRNAs in combatting this infectious disease.

Interleukin-18, Functional IL-18 Receptor and IL-18 Binding Protein Expression in Active and Latent Tuberculosis

A thorough understanding of the processes modulating the innate and acquired immune response to Mycobacterium tuberculosis (M.tb) infection in the context of gene expression is still a scientific and diagnostic problem. The study was aimed to assess IL-18, IL-18 binding protein (IL-18BP), IL-18R, IFN-γ, and IL-37 mRNA expression in patients with active tuberculosis (ATB) and healthy volunteers with latent M.tb-infection (LTB) or M.tb-uninfected healthy controls (Control). The relative mRNA expression was assessed in the buffy coat blood fraction using the qPCR method. In total, 97 BCG-vaccinated Polish adults were enrolled in the study. The relative expression of IL-18 and IL-18BP mRNA was significantly elevated in the ATB and LTB groups. In ATB, but not LTB individuals, the overexpression of IL-18 and IL-18BP, as well as a significant increase in IFN-γ mRNA expression, might be considered as a manifestation of active tuberculosis disease. No statistically significant differences were observed in the IL-37 mRNA expression among the studied groups. Particularly noteworthy is the outstanding reduction in the relative expression of IL-18R mRNA in the LTB group as compared to the ATB and Control group. Reduced expression of IL-18R in LTB group may, at least partially, prevent the development of a pathological inflammatory reaction and promote the maintenance of homeostatic conditions between host immunity and M.tb.

Risk alleles for tuberculosis infection associate with reduced immune reactivity in a wild mammalian host

Integrating biological processes across scales remains a central challenge in disease ecology. Genetic variation drives differences in host immune responses, which, along with environmental factors, generates temporal and spatial infection patterns in natural populations that epidemiologists seek to predict and control. However, genetics and immunology are typically studied in model systems, whereas population-level patterns of infection status and susceptibility are uniquely observable in nature. Despite obvious causal connections, organizational scales from genes to host outcomes to population patterns are rarely linked explicitly. Here we identify two loci near genes involved in macrophage (phagocyte) activation and pathogen degradation that additively increase risk of bovine tuberculosis infection by up to ninefold in wild African buffalo. Furthermore, we observe genotype-specific variation in IL-12 production indicative of variation in macrophage activation. Here, we provide measurable differences in infection resistance at multiple scales by characterizing the genetic and inflammatory variation driving patterns of infection in a wild mammal.

Discrimination between active and latent tuberculosis based on ratio of antigen-specific to mitogen-induced IP-10 production

Mycobacterium tuberculosis is the major causative agent of tuberculosis (TB). The gamma interferon (IFN-γ) release assay (IGRA) has been widely used to diagnose TB by testing cell-mediated immune responses but has no capacity for distinguishing between active TB and latent TB infection (LTBI). This study aims to identify a parameter that will help to discriminate active TB and LTBI. Whole-blood samples from 33 active TB patients, 20 individuals with LTBI, and 26 non-TB controls were applied to the commercial IFN-γ release assay, QuantiFERON-TB Gold In-Tube, and plasma samples were analyzed for interleukin-2 (IL-2), IL-6, IL-8, IL-10, IL-13, tumor necrosis factor-alpha (TNF-α), IFN-γ, monokine induced by IFN-γ (MIG), interferon gamma inducible protein 10 (IP-10), interferon-inducible T cell alpha chemoattractant (I-TAC), and monocyte chemoattractant protein 1 (MCP-1) by using a commercial cytometric bead array. The Mycobacterium tuberculosis antigen-specific production of most of the assayed cytokines and chemokines was higher in the active TB than in the LTBI group. The mitogen-induced responses were lower in the active TB than in the LTBI group. When the ratio of TB-specific to mitogen-induced responses was calculated, IL-2, IL-6, IL-10, IL-13, TNF-α, IFN-γ, MIG, and IP-10 were more useful in discriminating active TB from LTBI. In particular, most patients showed higher IP-10 production to Mycobacterium tuberculosis antigens than to mitogen at the individual level, and the ratio for IP-10 was the strongest indicator of active infection versus LTBI with 93.9% sensitivity and 90% specificity. In conclusion, the ratio of the TB-specific to the mitogen-induced IP-10 responses showed the most promising accuracy for discriminating active TB versus LTBI and should be further studied to determine whether it can serve as a biomarker that might help clinicians administer appropriate treatments.

Extra-pulmonary tuberculosis: a biomarker analysis

INTRODUCTION

Studies on biomarkers in tuberculosis are focused on pulmonary forms of this disease (PTB), and only limited information is currently available on biomarkers of extra-pulmonary tuberculosis (EPTB).

METHODS

Serum samples from 24 patients with PTB, 29 patients with EPTB and 27 healthy controls were obtained, and the levels of interferon-gamma, chemokine ligand 9, mannose-binding lectin (MBL), tumor marker Ca-125 and adenosine deaminase were determined.

RESULTS

The circulating levels of all tested biomarkers in the serum were significantly higher in PTB and EPTB patients than in controls. However, there were no significant differences in the levels of the biomarkers between patients with PTB and EPTB, with the exception of serum levels of MBL which were significantly higher in patients with EPTB than in patients with PTB (p = 0.01). In patients with EPTB, no significant differences were observed in biomarker levels among patients with or without concomitant PTB involvement. Based on MBL serum levels, ROC curve analysis showed an AUC of 0.85 for EPTB versus non-EPTB. The optimal cut-off value of MBL serum levels for EPTB versus non-EPTB was 1,000 μg/ml, with a sensitivity and specificity of 79.3 and 78.0 %, respectively.

CONCLUSIONS

Biomarkers usually present as acute phase reactants and do not enable pulmonary forms to be differentiated from more serious or extra-pulmonary forms. MBL may be an exception.

Sarcoidosis and tuberculosis cytokine profiles: indistinguishable in bronchoalveolar lavage but different in blood

Background

The clinical, radiological and pathological similarities between sarcoidosis and tuberculosis can make disease differentiation challenging. A complicating factor is that some cases of sarcoidosis may be initiated by mycobacteria. We hypothesised that immunological profiling might provide insight into a possible relationship between the diseases or allow us to distinguish between them.

Methods

We analysed bronchoalveolar lavage (BAL) fluid in sarcoidosis (n = 18), tuberculosis (n = 12) and healthy volunteers (n = 16). We further investigated serum samples in the same groups; sarcoidosis (n = 40), tuberculosis (n = 15) and healthy volunteers (n = 40). A cross-sectional analysis of multiple cytokine profiles was performed and data used to discriminate between samples.

Results

We found that BAL profiles were indistinguishable between both diseases and significantly different from healthy volunteers. In sera, tuberculosis patients had significantly lower levels of the Th2 cytokine interleukin-4 (IL-4) than those with sarcoidosis (p = 0.004). Additional serum differences allowed us to create a linear regression model for disease differentiation (within-sample accuracy 91%, cross-validation accuracy 73%).

Conclusions

These data warrant replication in independent cohorts to further develop and validate a serum cytokine signature that may be able to distinguish sarcoidosis from tuberculosis. Systemic Th2 cytokine differences between sarcoidosis and tuberculosis may also underly different disease outcomes to similar respiratory stimuli.

Prevalence, distribution and functional significance of the -237C to T polymorphism in the IL-12Rβ2 promoter in Indian tuberculosis patients

Cytokine/cytokine receptor gene polymorphisms related to structure/expression could impact immune response. Hence, the −237 polymorphic site in the 5′ promoter region of the IL-12Rβ2 (SNP ID: rs11810249) gene associated with the AP-4 transcription motif GAGCTG, was examined. Amplicons encompassing the polymorphism were generated from 46 pulmonary tuberculosis patients, 35 family contacts and 28 miscellaneous volunteers and sequenced. The C allele predominated among patients, (93.4%, 43/46), and in all volunteers and contacts screened, but the T allele was exclusively limited to patients, (6.5%, 3/46). The functional impact of this polymorphism on transcriptional activity was assessed by Luciferase-reporter and electrophoretic mobility shift assays (EMSA). Luciferase-reporter assays showed a significant reduction in transcriptional efficiency with T compared to C allele. The reduction in transcriptional efficiency with the T allele construct (pGIL-12Rb2-T), in U-87MG, THP-1 and Jurkat cell lines, were 53, 37.6, and 49.8% respectively, compared to the C allele construct (pGIL-12Rb2-C). Similarly, densitometric analysis of the EMSA assay showed reduced binding of the AP-4 transcription factor, to T compared to the C nucleotide probe. Reduced mRNA expression in all patients (3/3) harboring the T allele was seen, whereas individuals with the C allele exhibited high mRNA expression (17/25; 68%, p = 0.05). These observations were in agreement with the in vitro assessment of the promoter activity by Luciferase-reporter and EMSA assays. The reduced expression of IL-12Rβ2 transcripts in 8 patients despite having the C allele was attributed to the predominant over expression of the suppressors (IL-4 and GATA-3) and reduced expression of enhancers (IFN-α) of IL-12Rβ2 transcripts. The 17 high IL-12Rβ2 mRNA expressers had significantly elevated IFN-α mRNA levels compared to low expressers and volunteers. Notwithstanding the presence of high levels of IL-12Rβ2 mRNA in these patients elevated IFN-α expression could modulate their immune responses to Mycobacterium tuberculosis.

Mycobacteria and biological response modifiers: two sides of the relationship

With increasing use of biological response modifiers (BRMs) for various systemic inflammatory diseases there is a need to be vigilant about complications with the use of these therapies. It is important to have appropriate screening for the infections in patients requiring BRMs. However, many studies have reported benefits of certain BRMs in the treatment of infections such as tuberculosis as adjuncts. Continued research and technical advances in immunogenetics helps understand complex mechanisms in the usage of the BRMs. This article summarizes the different aspects of the relationship between mycobacterial infections and the use of various BRMs for inflammatory conditions.

MMP-1 drives immunopathology in human tuberculosis and transgenic mice

Mycobacterium tuberculosis can cause lung tissue damage to spread, but the mechanisms driving this immunopathology are poorly understood. The breakdown of lung matrix involves MMPs, which have a unique ability to degrade fibrillar collagens at neutral pH. To determine whether MMPs play a role in the immunopathology of tuberculosis (TB), we profiled MMPs and their inhibitors, the tissue inhibitor of metalloproteinases (TIMPs), in sputum and bronchoalveolar lavage fluid from patients with TB and symptomatic controls. MMP-1 concentrations were significantly increased in both HIV-negative and HIV-positive patients with TB, while TIMP concentrations were lower in HIV-negative TB patients. In primary human monocytes, M. tuberculosis infection selectively upregulated MMP1 gene expression and secretion, and Ro32-3555, a specific MMP inhibitor, suppressed M. tuberculosis-driven MMP-1 activity. Since the mouse MMP-1 ortholog is not expressed in the lung and mice infected with M. tuberculosis do not develop tissue destruction equivalent to humans, we infected transgenic mice expressing human MMP-1 with M. tuberculosis to investigate whether MMP-1 caused lung immunopathology. In the MMP-1 transgenic mice, M. tuberculosis infection increased MMP-1 expression, resulting in alveolar destruction in lung granulomas and significantly greater collagen breakdown. In summary, MMP-1 may drive tissue destruction in TB and represents a therapeutic target to limit immunopathology.

Increased frequencies of T helper type 17 cells in tuberculous pleural effusion

Th17 cells have emerged as an important mediator in inflammatory and autoimmune diseases. Recent studies suggest a potential impact of Th17 cells on tuberculosis (TB) infection. This study was designed to investigate the possible involvement of Th17 cells in tuberculous pleural effusion. Compared with healthy volunteers, patients with TB had a higher proportion of Th17 cells in peripheral blood mononuclear cells (PBMCs). Moreover, the percentage of Th17 cells in pleural effusions of TB patients was obviously higher than that in PBMC from TB patients or healthy controls. Furthermore, the mRNA and protein expression levels of IL-17 and IL-6 were significantly increased in the patients with tuberculous pleural effusion, while expression level of TGF-β was decreased in the pleural effusion. Correlation analysis showed a significant correlation between IFN-γ concentrations and the frequencies of Th17 cells in tuberculous pleural effusion. These results indicate that Th17 cells may contribute to the immunopathogenesis of tuberculous pleural effusion.

Pleural fluid from tuberculous pleurisy inhibits the functions of T cells and the differentiation of Th1 cells via immunosuppressive factors

Immunosuppressive mediators in tuberculosis pleurisy (pleural fluid (PF)) are associated with the course of disease, but they remain poorly defined. To study the local immune status of patients with tuberculosis pleurisy, we examined the effect of PF on the functions of T cells and the differentiation of Th1 cells. PF could inhibit the ability of T cells to produce cytokines. However, tumor-necrosis factor (TNF)-α derived from non-T cells was not impaired. Further analysis indicated that cell activation and cell cycle progression were also suppressed. Moreover, PF could inhibit Th1 cell differentiation. Importantly, we found that inhibitors of indoleamine 2,3-dioxygenase (IDO) and adenosine and neutralizing antibodies against IL-10 and transforming growth factor (TGF)-β could reverse cytokine production, suggesting that IDO, adenosine, IL-10 and Transforming growth factor-β1 in PF might take part in impairing T-cell functions. Taken together, our data demonstrate for the first time that several immunopathological factors participate in the downregulation of T-cell functions in local PF.

Assessment of the IgA immunoassay diagnostic potential of the Mycobacterium tuberculosis MT10.3-MPT64 fusion protein in tuberculous pleural fluid

Pleural tuberculosis (PL-TB) remains difficult to diagnose. An enzyme-linked immunosorbent assay (ELISA) was developed based on a construction containing the fusion of the Rv3019c (MT10.3) and Rv1980c (MPT64) gene sequences, and its performance was evaluated in an area where TB is endemic. A total of 92 pleural fluid (PF) samples at serial dilutions of 1:50 to 1:800 were included in the ELISA IgA MT10.3-MPT64 evaluation: 70 from TB patients and 22 from patients with other pleurisies. Confirmation of the expression and subsequent purification of the protein was made by SDS-PAGE and Western blot assays, resulting in a 36-kDa protein. ELISA IgA MT10.3-MPT64 showed sensitivities of 61.4%, 58.6%, 62.9%, 67.1%, and 70% at each PF dilution, respectively. The cumulative results of all dilutions increased sensitivity to 81.4% without jeopardizing specificity. Similar results were also obtained at the combined dilutions of 1:50, 1:200, and 1:800 or 1:50 plus 1:800 dilutions (80%). The overall sensitivity of the reference test, i.e., histopathological examination, was 74%. But, via the ELISA IgA MT10.3-MPT64 test, sensitivity was high for specimens with a negative culture (23/27; 85.2%) or nonspecific histopathology (17/18; 94.4%). Our findings demonstrated the promising use of this test as an adjunct in PL-TB diagnoses, particularly in cases with lower bacterial loads and false-negative results in the reference tests, since the new test includes such important features as quick and easy application, high sensitivity and, perhaps most importantly, affordability, which is so crucial for its widespread use in developing countries.

The immunology of tuberculosis: from bench to bedside

Tuberculosis (TB) is an international public health priority and kills almost two million people annually. TB is out of control in Africa due to increasing poverty and HIV coinfection, and drug-resistant TB threatens to destabilize TB control efforts in several regions of the world. Existing diagnostic tools and therapeutic interventions for TB are suboptimal. Thus, new vaccines, immunotherapeutic interventions and diagnostic tools are urgently required to facilitate TB control efforts. An improved understanding of the immunopathogenesis of TB can facilitate the identification of correlates of immune protection, the design of effective vaccines, the rational selection of immunotherapeutic agents, the evaluation of new drug candidates, and drive the development of new immunodiagnostic tools. Here we review the immunology of TB with a focus on aspects that are clinically and therapeutically relevant. An immunologically orientated approach to tackling TB can only succeed with concurrent efforts to alleviate poverty and reduce the global burden of HIV.

Ca-125: a useful marker to distinguish pulmonary tuberculosis from other pulmonary infections

Introduction:

Ca-125 is secreted by different celomic epitheliums. Serum levels may be increased in malignant diseases, like ovarian cancer but also in other medical conditions, such as pulmonary and extrapulmonary tuberculosis.

Methods:

From Jan-04 to Dec-06 a retrospective study analyzing Ca-125 levels in serum samples from patients with a diagnosis of pulmonary TB, was performed. These results were compared with those samples obtained from patients with non-TB pulmonary infections.

Results:

Eighty-nine patients were included in the study, thirty-five with pulmonary TB and 54 with other respiratory infections. In patients with TB, the mean Ca-125 value was 104.9 IU/ml (SD: ± 136.1). In the control group, mean value was 27.1 IU/ml (SD: ±19.7). The optimal cut-off for pulmonary tuberculosis was 32.5 IU/ml (sensitivity: 68.6%, specificity: 77.8%). Pulmonary TB was the only factor associated with a Ca-125 level >32.5. In 10 patients with TB, Ca-125 levels were available ≥ 2 months after starting TB therapy and a decrease during treatment was shown.

Conclusions:

Ca-125 values increase in patients with pulmonary TB and decline to normal values during treatment. Determination of Ca 125 may be usedin patients with a negative sputum AFB stain.

THE EFFECTS OF INHALATION OF DIESEL EXHAUST ON MURINE MYCOBACTERIAL INFECTION

The authors investigated the effects of inhalation of diesel exhaust (DE) on murine mycobacterial infection in vivo. Eight-week-old female BALB/c mice were exposed to DE (3 mg/m3 of diesel exhaust particles [DEPs]) for 1 month, 2 months, or 6 months (for 7 hours a day, 5 days a week). Control mice were housed in a clean room for the same periods. On the day following the last DE exposure, control mice and DE-exposed mice were aerially infected with Mycobacterium tuberculosis (1 x 10(6) colony-forming units (CFU), Kurono strain). At 7 weeks after mycobacterial infection, the authors examined the lung tissues for histopathological changes and performed reverse transcriptase-polymerase chain reaction (RT-PCR) to measure the messenger RNA (mRNA) expression of several proinflammatory cytokines and inducible nitric oxide synthase (iNOS). Then, the homogenates of lungs and spleens were cultured on 1% (v/v) Ogawa's egg slant medium, and after a 4-week incubation period at 37 degrees C, colonies on the medium were counted. After 1 month of DE exposure, the mycobacterial infection had slightly ameliorated. After 2 months of DE exposure, the expression levels of tumor necrosis factor (TNF)-alpha, interleukin (IL)-1beta, IL-12p40, interferon (IFN)-gamma, and iNOS mRNAs were slightly increased. However, after 6 months of DE exposure, the expression levels of IL-1beta , IL-12p40, IFN-gamma, and iNOS mRNAs were decreased, and the infection as measured by increased lung burden (CFU) actually increased. These results indicate that long-term DE exposure may increase pulmonary mycobacterial burden.

Increased levels of immunological markers in the respiratory tract but not in serum correlate with active pulmonary mycobacterial infection in mice

Immunological tests for the diagnosis of tuberculosis (TB) have relied mostly on detection of immune markers in serum or release of cytokines by mononuclear cells in vitro. These tests, although useful, sometimes fail to discriminate between active infection and contact with mycobacteria or vaccination. TB is primarily a disease of the lung, and therefore identification of immunological markers in the respiratory tract will be more likely to reflect the infection status or disease activity. In this study, it is demonstrated that active infection of mice with Mycobacterium bovis bacille Calmette-Guérin (BCG), but not exposure to heat-killed BCG, induced production of interleukin-12 (IL-12), interferon-gamma (IFN-gamma) or soluble tumour necrosis factor receptors (sTNFRs) locally in the lungs, as detected in bronchoalveolar lavage (BAL) fluid. There was a strong correlation between bacterial growth in the lung and levels of sTNFRs, and to some extent IL-12 and IFN-gamma, in BAL fluid. Furthermore, sTNFR levels increased significantly in BAL fluid after reactivation of controlled infection with dexamethasone, and this correlated with increased bacterial growth in the lungs. Finally, infection, but not exposure to non-replicating mycobacteria, induced specific IgG and IgA in BAL fluid. Elevated levels of all biomarkers measured were also detected in the serum, but correlation with infection was not as clear as in the case of BAL fluid. Taken together, the detection of sTNFRs and mycobacterium-specific antibodies, especially IgA, locally in the lungs could be used as immunological markers for the diagnosis of TB.

Th1-Th2 polarisation and autophagy in the control of intracellular mycobacteria by macrophages

Autophagy is a major intracellular pathway for the lysosomal degradation of long-lived cytoplasmic macromolecules and damaged or surplus organelles. More recently, autophagy has also been linked with innate and adaptive immune responses against intracellular pathogens, including Mycobacterium tuberculosis, which can survive within macrophages by blocking fusion of the phagosome with lysosomes. Induction of autophagy by the Th1 cytokine IFN-gamma enables infected macrophages to overcome this phagosome maturation block and inhibit the intracellular survival of mycobacteria. Conversely, the Th2 cytokines IL-4 and IL-13 inhibit autophagy in murine and human macrophages. We discuss how differential modulation of autophagy by Th1 and Th2 cytokines may represent an important feature of the host response to mycobacteria.

Compartmentalized bronchoalveolar IFN-gamma and IL-12 response in human pulmonary tuberculosis

Human tuberculosis (TB) principally involves the lungs, where local immunity impacts on the load of Mycobacterium tuberculosis (M.tb). Because concomitants of local Th1 immunity are still under-explored in humans, we characterized immune responses in bronchoalveolar cells (BACs) and systemically in peripheral blood mononuclear cells (PBMCs) in persons with active pulmonary TB and in healthy community controls. PPD- and live M.tb-induced IFN-gamma-production were observed in CD4(+), CD8(+), gammadeltaTCR(+), and CD56(+) alveolar T cell subpopulations and NK cells (CD3(-)CD56(+)). IFN-gamma-producing CD4(+) T cells (mostly CD45RO(+)) were more abundant (p<0.05). M.tb-induced IL-12p70, but interestingly also IL-4, was increased (p<0.05) in BACs from TB patients. Constitutive expression of IL-12Rbeta1 and IL-12Rbeta2 mRNA in BACs and PBMCs and IFN-gammaR1 in BACs was similar in both study groups. Data were normalized to account for differences in proportions of alveolar T cells and macrophages in the study groups. IFN-gamma-production and its induction by IL-12R engagement occur virtually unimpaired in the bronchoalveolar spaces of patients with pulmonary TB. The reasons for the apparent failure to control M. tuberculosis growth during active pulmonary TB disease is unknown but could be the expression of locally acting immunosuppressive mechanisms that subvert the antimycobacterial effects of IFN-gamma.

T helper 2 cytokines inhibit autophagic control of intracellular Mycobacterium tuberculosis

Autophagy is a recently recognized immune effector mechanism against intracellular pathogens. The role of autophagy in innate immunity has been well established, but the extent of its regulation by the adaptive immune response is less well understood. The T helper 1 (Th1) cell cytokine IFN-gamma induces autophagy in macrophages to eliminate Mycobacterium tuberculosis. Here, we report that Th2 cytokines affect autophagy in macrophages and their ability to control intracellular M. tuberculosis. IL-4 and IL-13 abrogated autophagy and autophagy-mediated killing of intracellular mycobacteria in murine and human macrophages. Inhibition of starvation-induced autophagy by IL-4 and IL-13 was dependent on Akt signaling, whereas the inhibition of IFN-gamma-induced autophagy was Akt independent and signal transducer and activator of transcription 6 (STAT6) dependent. These findings establish a mechanism through which Th1-Th2 polarization differentially affects the immune control of intracellular pathogens.

Lymphocyte subpopulations in pulmonary tuberculosis patients

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

Cytokine profiles in tuberculosis patients and healthy subjects in response to complex and single antigens of Mycobacterium tuberculosis

Peripheral blood mononuclear cells (PBMC) were obtained from tuberculosis (TB) patients and Mycobacterium bovis bacillus Calmette-Guerin vaccinated healthy subjects. PBMC were tested for secretion of tumor necrosis factor-alpha (TNF-alpha), interferon-gamma (IFN-gamma), interleukin-5 (IL-5) and IL-10 in response to complex (whole cells, culture filtrate and cell walls), single secreted (Ag85B, ESAT6, MPT64, PstS and MPT70) and single cytosolic (DnaK, GroES and GroEL) antigens of Mycobacterium tuberculosis. In the absence of antigens, detectable concentrations of TNF-alpha, IFN-gamma and IL-10 were secreted by PBMC of both donor groups, but the concentrations of only IL-10 were significantly higher (P=0.015) in TB patients than in healthy subjects. In the presence of complex antigens, PBMC secreted IFN-gamma and TNF-alpha in response to all three preparations, whereas IL-10 was secreted in response to whole cells and cell walls only. In the presence of single antigens, IFN-gamma was secreted in response to Ag85B, ESAT6 and MPT64 in TB patients and ESAT6 in healthy donors. Except for GroEL and DnaK, single antigens did not induce TNF-alpha and IL-10 secretion from PBMC in either donor group. The secretion of IFN-gamma, but not IL-10, in the presence of Ag85B, ESAT6 and MPT64 supports their potential as subunit vaccine candidates against TB.

Changes in serum cytokine levels in active tuberculosis with treatment

It has been reported that IFN-γ, TNF-α, and IL-12 stimulate, and that IL-10, TGF-β, and IL-4 suppress the protective immune response against tuberculosis. We aim to evaluate changes in the serum levels of pro and antiinflammatory cytokines in active pulmonary tuberculosis (APTB) and the possible effects of treatment on these changes. Serum IL-12p40, IL-4, IL-10, TNF-α, IFN-γ, and TGF-β1 levels were determined in 20 APTB cases (group 1) before and 2, 4, and 6 months after therapy. The same parameters were also determined in 9 inactive pulmonary tuberculosis (IPTB) cases (group 2) and 9 healthy controls (HC, group 3). Before treatment, the mean serum IFN-γ, TNF-α, and IL-10 levels in group 1 were statistically higher than those in group 2 (P = .001, P = .024, P = .016, resp) or group 3 (P = .003, P = .002, P = .011, resp). The levels in group 1 decreased significantly after treatment (P = .001 for IFN-γ, P = .004 for TNF-α, P = .000 for IL-10). The serum levels of IL-12p40 were significantly higher in group 1 than in group 3 (P = .012) and decreased insignificantly after treatment. There was no difference in serum IL-4 and TGF-β1 levels among the groups (P > .05). Because the serum IL-12p40, IL-10, TNF-α, and IFN-γ levels were high in APTB, we believe that these cytokines have important roles in the immune response to Mycobacterium tuberculosis (M tuberculosis). These parameters could be used in follow-up as indicators of the success of APTB therapy.

Cytokine profile during latent and slowly progressive primary tuberculosis: a possible role for interleukin-15 in mediating clinical disease

Recently, mouse models for latent (LTB) and slowly progressive primary tuberculosis (SPTB) have been established. However, cytokine profiles during the two models are not well established. Using quantitative reverse transcription-polymerase chain reaction (qRT-PCR) we studied the expression levels of interleukin (IL)-2, IL-4, IL-10, IL-12, IL-15, interferon (IFN)-gamma and tumour necrosis factor (TNF)-alpha during the course of LTB and SPTB in the lungs and spleens of B6D2F1Bom mice infected with the H37Rv strain of Mycobacterium tuberculosis (Mtb). The results show that, except for IL-4, cytokine expression levels were significantly higher during SPTB than LTB in both the lungs and spleens. During LTB, all the cytokines (except IL-2 in the lungs) had higher expression levels during the initial period of infection both in the lungs and spleens. During SPTB, the expression levels of IL-15 increased significantly from phases 1 to 3 in the lungs. The expression levels of IL-10, IL-12 and IFN-gamma increased significantly from 2 to 3 in the lungs. IL-10 and IL-15 increased significantly from phases 2 to 3, whereas that of TNF-alpha decreased significantly and progressively from phases 1 to 3 in the spleens. Over-expression of proinflammatory cytokines during active disease has been well documented, but factor(s) underlying such over-expression is not known. In the present study, there was a progressive and significant increase in the expression levels of IL-15, together with Th1 cytokines (IL-12 and IFN-gamma) during SPTB but a significant decrease during LTB. IL-15 is known to up-regulate the production of proinflammatory cytokines, IL-1beta, IL-8, IL-12, IL-17, IFN-gamma and TNF-alpha and has an inhibitory effect on activation-induced cell death. IL-15 is known to be involved in many proinflammatory disease states such as rheumatoid arthritis, sarcoidosis, inflammatory bowel diseases, autoimmune diabetes, etc. Our results, together with the above observations, suggest that IL-15 may play an important role in mediating active disease during Mtb infection.

Protective efficacy induced by Mycobacterium bovis bacille Calmette-Guèrin can be augmented in an antigen independent manner by use of non-coding plasmid DNA

Tuberculosis caused by infection with Mycobacterium tuberculosis or M. bovis remains one of the most important infectious diseases of man and animals, and continues to inflict a huge cost in both health and financial terms. The current vaccine, BCG demonstrates variable efficacy and so a more robust vaccine strategy to either replace or supplement BCG is required. We have utilised a DNA prime-BCG boost strategy in a murine M. bovis challenge model using a cocktail of 3 DNA vaccines (encoding Hsp65, Hsp70 and Apa) followed by BCG. Controls were inoculated with vector DNA only, coding DNA only, BCG only or vector DNA followed by BCG boost. Analysis of immune responses by ELISpot prior to challenge, revealed that the coding DNA/BCG prime boost resulted in an increased frequency of antigen-specific IFNgamma producing cells compared to the other regimes. When spleen cell cytokine production to BCG antigens was analysed, significantly more IFNgamma and IL-12 was seen in those groups primed with DNA (coding or vector) prior to BCG than those receiving BCG alone. Analysis of bacterial counts revealed that DNA priming followed by BCG boost further improved the protective immunity induced by BCG alone. Surprisingly, inoculation with vector DNA was as efficacious as the coding DNA in enhancing BCG protection. Taken together these results indicate that whilst the coding DNA vaccines induce antigen specific responses, treatment with the vector DNA is sufficient for the increase in protective immunity over that induced by BCG, suggesting that the vector DNA may be acting as a non-specific adjuvant for BCG immunization.

Frequency of IFN-gamma producing cells correlates with adjuvant enhancement of bacille Calmette-Guèrin induced protection against Mycobacterium bovis

Tuberculosis caused by infection with Mycobacterium tuberculosis or Mycobacterium bovis remains one of the most important infectious diseases of man and animals. The current vaccine M. bovis Calmette-Guérin (BCG) demonstrates variable efficacy and so a more robust strategy to either replace, or more likely supplement it, is required. Prime-boost strategies where immunity induced by BCG is boosted by a second heterologous vaccine represent a promising avenue of research. We have evaluated the ability of a protein subunit vaccine using the antigen Rv3019c to either prime or boost immunity induced by BCG in a murine M. bovis challenge model. Despite the induction of anamnestic T cell responses, we report that antigen-independent immune stimulation with adjuvant in conjunction with BCG could enhance the level of protection induced by BCG alone. Importantly this improved protection correlated with pre-infection frequencies of ex vivo IFN-gamma producing cells in the spleen, providing a possible surrogate correlate of protection for future vaccination studies.

Protective immunity against Mycobacterium bovis induced by vaccination with Rv3109c--a member of the esat-6 gene family

In a number of clinical studies the current TB vaccine, Mycobacterium bovis bacille Calmette-Guerin (BCG), has provided little or no protection against pulmonary tuberculosis in cattle and man. A new generation of vaccines is therefore required to replace or supplement BCG. Safety concerns surrounding a number of strategies make protein subunits an attractive approach. Moreover, novel prime-boost strategies based on primary immunisations with BCG are not only showing promise but also present a clear strategy for testing new TB vaccines in clinical studies. We report the evaluation of six protein vaccine candidates for their ability to induce protective immunity in a murine virulent M. bovis challenge model. One protein (Rv3019c) induced reproducibly significant protection in the spleen and lungs approaching that induced by BCG. Detailed analysis of antigen-specific T cell responses revealed that despite robust responses in the spleen and lungs of vaccinated mice, there was no correlation between these responses and the protective efficacy of the vaccine. Significantly, Rv3019c also stimulated IFN-gamma responses in PBMC from BCG vaccinated cattle, indicating its potential for use in a heterologous prime-boost strategy in conjunction with BCG in the target species.

Change in serum concentrations of interleukin-2 and interferon-gamma during treatment of tuberculosis

We aimed to investigate changes in serum concentrations of the cytokines interleukin (IL)-2 and interferon (IFN)-gamma during the clinical course of active tuberculosis, to establish the presence of cellular immunity before and after treatment. Blood samples were taken from 18 patients with active tuberculosis before and 2 months after therapy; IL-2 and IFN-gamma concentrations were evaluated. The mean serum IL-2 concentration before therapy was 164.5 pg/ml (range 12-980 pg/ml) and the concentration 2 months after therapy was 92.11 pg/ml (range 1-490 pg/ml). The mean serum IFN-gamma concentrations were 10.83 pg/ml (range 1-22.2 pg/ml) and 4.64 pg/ml (range 1-28.5 pg/ml), respectively. The decrease in concentrations of both cytokines after therapy was statistically significant. Further studies investigating the benefits of adding cytokines to drug treatment for tuberculosis are needed.

Dendritic cell trafficking and antigen presentation in the human immune response to Mycobacterium tuberculosis

Mycobacterium tuberculosis (Mtb) is an extraordinarily successful human pathogen, one of the major causes of death by infectious disease worldwide. A key issue for the study of tuberculosis is to understand why individuals infected with Mtb experience different clinical outcomes. To better understand the dynamics of Mtb infection and immunity, we coupled nonhuman primate experiments with a mathematical model we previously developed that qualitatively and quantitatively captures important processes of cellular priming and activation. These processes occur between the lung and the nearest draining lymph node where the key cells mediating this process are the dendritic cells (DC). The nonhuman primate experiments consist of bacteria and cell numbers from tissues of 17 adult cynomolgus macaques (Macaca fascicularis) that were infected with Mtb strain Erdman ( approximately 25 CFU/animal via bronchoscope). The main result of this work is that delays in either DC migration to the draining lymph node or T cell trafficking to the site of infection can alter the outcome of Mtb infection, defining progression to primary disease or latent infection and reactivated tuberculosis. Our results also support the idea that the development of a new generation of treatment against Mtb should optimally elicit a fast DC turnover at the site of infection, as well as strong activation of DCs for maximal Ag presentation and production of key cytokines. This will induce the most protective T cell response.

Down-modulation of lung immune responses by interleukin-10 and transforming growth factor beta (TGF-beta) and analysis of TGF-beta receptors I and II in active tuberculosis

Immune factors influencing progression to active tuberculosis (TB) remain poorly defined. In this study, we investigated the expression of immunoregulatory cytokines and receptors by using lung bronchoalveolar lavage cells obtained from patients with pulmonary TB, patients with other lung diseases (OLD patients), and healthy volunteers (VOL) by using reverse transcriptase PCR, a transforming growth factor beta (TGF-beta) bioactivity assay, and an enzyme immunoassay. TB patients were significantly more likely than OLD patients to coexpress TGF-beta receptor I (RI) and RII mRNA, as well as interleukin-10 (IL-10) mRNA (thereby indicating the state of active gene transcription in the alveolar cells at harvest). In contrast, gamma interferon (IFN-gamma) and IL-2 mRNA was seen in both TB and OLD patients. Likewise, significantly elevated pulmonary steady-state protein levels of IL-10, IFN-gamma, and bioactive TGF-beta were found in TB patients versus those in OLD patients and VOL. These data suggest that the combined production of the immunosuppressants IL-10 and TGF-beta, as well as coexpression of TGF-beta RI and RII (required for cellular response to TGF-beta), may act to down-modulate host anti-Mycobacterium tuberculosis immunity and thereby allow uncontrolled bacterial replication and overt disease. Delineating the underlying mechanisms of M. tuberculosis-triggered expression of these immune elements may provide a molecular-level understanding of TB immunopathogenesis.

Expression of IL-27 in human Th1-associated granulomatous diseases

Interleukin (IL)-27 is a newly described member of the IL-12 family. It is a heterodimeric cytokine composed of two subunits, p28 and Epstein-Barr virus-induced gene 3 (EBI3). In vitro studies have shown that IL-27 is mainly produced by activated monocytes and dendritic cells. It induces the proliferation of naïve CD4-positive T cells and synergizes with IL-12 for interferon-gamma (IFN-gamma) production. Knock-out mice for the IL-27 receptor (WSX-1/TCCR) have impaired Th1 responses and form abnormal granulomas when injected with bacillus Calmette-Guérin. However, the expression profile of IL-27 in vivo is currently unknown. To investigate the potential role of IL-27 in the development of a Th1 response in humans in vivo, this study has analysed the in situ expression of IL-27 subunits in three types of granulomatous disease (tuberculosis, sarcoidosis, and Crohn's disease), each characterized by a Th1 response. Tissue sections from patients with tuberculosis (n = 9), sarcoidosis (n = 8), or Crohn's disease (n = 7) were analysed by immunohistochemistry with anti-EBI3 and anti-p28 antibodies, in parallel with control tissues (control reactive lymph nodes, n = 14, and control intestinal tissues, n = 11). In granulomatous tissues, EBI3 and p28 co-expression was detected in epithelioid and multinucleate giant cells in granulomas. In addition, sinus or tissue macrophages, endothelial cells, and plasma cells were found to co-express EBI3 and p28. These data support a possible role for IL-27 in human Th1 responses.

In situ study of abundant expression of proinflammatory chemokines and cytokines in pulmonary granulomas that develop in cynomolgus macaques experimentally infected with Mycobacterium tuberculosis

Tuberculosis remains a major public health problem worldwide. Chemokines and cytokines organize and direct infiltrating cells to sites of infection, and these molecules likely play crucial roles in granuloma formation and maintenance. To address this issue, we used in situ hybridization (ISH) to measure chemokine and cytokine mRNA expression levels and patterns directly in lung tissues from cynomolgus macaques (Macaca fascicularis) experimentally infected with a low dose of virulent Mycobacterium tuberculosis. We examined more than 300 granulomas and observed abundant expression of gamma interferon (IFN-gamma)-inducible chemokine mRNAs (CXCL9/monokine induced by IFN-gamma, CXCL10/IFN-gamma-inducible protein, and CXCL11/IFN-gamma-inducible T-cell alpha-chemoattractant) within solid and caseous granulomas, and there was only minimal expression in nongranulomatous regions of tissue. The mRNA expression patterns of IFN-gamma and tumor necrosis factor alpha were examined in parallel, and the results revealed that cytokine mRNA(+) cells were abundant and generally localized to the granulomas. Mycobacterial 16S rRNA expression was also measured by ISH, and the results revealed that there was localization predominantly to the granulomas and that the highest signal intensity was in caseous granulomas. We observed several granulomatous lesions with exceptionally high levels of RNA for mycobacterial 16S rRNA, IFN-gamma, and IFN-gamma-inducible chemokines, suggesting that the local presence of mycobacteria is partially responsible for the upregulation of IFN-gamma-inducible chemokines and recruitment of CXCR3(+) cells, which were also abundant in granulomatous lesions. These results suggest that expression of CXCR3 ligands and the subsequent recruitment of CXCR3(+) cells are involved in granuloma formation and maintenance.

Anti-inflammatory effect of Pelteobagrus nudiceps extract on rat model of CFA-induced pulmonary tuberculous granuloma

We investigated the effectiveness of supportive therapy with a fish-oil extract called repair tuberculosis (RTB) in anti-tuberculosis treatment, and the underlying mechanism of action. The active component of RTB is the unsaturated fatty acid docosatetraenoic acid (C(22)H(36)O(2)), which was reported to induce the resorption and healing of pulmonary lesions in patients with severe pulmonary tuberculosis. We administered RTB to a rat model of CFA-induced pulmonary tuberculous granuloma (RTB group), and compared the results with those in a control group, which did not receive RTB. Histological examination of the lungs showed a significantly smaller area of granuloma in the RTB group than in the control group. IFN-gamma levels in bronchoalveolar lavage fluid (BALF) were higher in the RTB group than in the control group, suggesting that Th1-type immune reaction is activated in the RTB group. Moreover, significantly enhanced expression of inducible nitric oxide synthase mRNA in lung tissue was observed in the RTB group. Superoxide production by cells recovered from BALF was attenuated in the RTB group. There were no difference in IL-4 levels in BALF, or in expression of TNF-alpha mRNA in lung tissue between the RTB and control groups. The above results suggest that RTB activates Th1-type cellular immune reaction, promotes absorption of lesions, and inhibits the generation of cytotoxic substances.

High plasma osteopontin level and its relationship with interleukin-12-mediated type 1 T helper cell response in tuberculosis

Osteopontin (OPN, also known as Eta-1), a noncollagenous matrix protein produced by macrophages and T lymphocytes, is expressed in granulomatous lesions caused by Mycobacterium tuberculosis infection. In the present study, we compared plasma concentrations of OPN in patients with active pulmonary tuberculosis with those of healthy control subjects and patients with sarcoidosis, another disease associated with granuloma formation. Plasma OPN levels were significantly higher in patients with tuberculosis (n = 48) than in control subjects (n = 34) and patients with sarcoidosis (n = 20). OPN levels correlated well with severity of pulmonary tuberculosis, as indicated by the size of lung lesions on chest X-ray films. Furthermore, chemotherapy resulted in a significant fall in plasma OPN levels. In patients with tuberculosis, plasma OPN concentrations correlated significantly with those of interleukin (IL)-12. In vitro experiments showed that OPN production by peripheral blood mononuclear cells infected with Mycobacterium bovis bacillus Calmette-Guérin preceded the synthesis of IL-12 and interferon-gamma and that the neutralizing anti-OPN monoclonal antibody significantly reduced the production of IL-12 and interferon-gamma. Our results suggest that OPN may be involved in the pathologic process associated with active pulmonary tuberculosis by inducing IL-12-mediated type 1 T helper cell responses.

T lymphocyte phenotypic profile in lung segments affected by cavitary and non-cavitary tuberculosis

Clinical manifestations of pulmonary tuberculosis (TB) may depend on a complex interaction between the host and the pathogen. Clinical outcomes of pulmonary tuberculosis are variable, ranging from asymptomatic lifelong infection to parenchymal lung destruction, resulting in cavitary lesions. To investigate the hypothesis that local cellular immune response may affect presentation and outcome in tuberculosis, we performed bronchoalveolar lavage (BAL) in lung segments affected by cavitary and non-cavitary tuberculosis. We then correlated the type of cellular response at the level of the involved lung segments with clinical evolution in terms of cavity formation. We found alveolar lymphocytosis in patients with both cavitary and non-cavitary pulmonary tuberculosis, with increased CD4+ lymphocytes in patients with non-cavitary pulmonary tuberculosis. A predominant Th1 immune response has been observed in non-cavitary patients, while cavitary involved segments exhibit the presence of Th2 lymphocyte subsets. These data, while confirming the importance of Th1-type CD4+ cells and IFN-gamma in effective cellular immunity in active pulmonary tuberculosis, also suggest that the presence of Th2 lymphocytes may contribute to tissue necrosis phenomena associated with cavitary evolution of pulmonary tuberculosis. Our observations indicate the importance of the type of local immune response at the site of disease in the development of different clinical characteristics and outcome in pulmonary tuberculosis.

Cytokine polarization in miliary and pleural tuberculosis

Cytokines were measured in patients with pleural effusion and miliary tuberculosis (TB). Patients with pleural effusion had significantly higher interferon-gamma (IFN-gamma) levels (P < 0.001) in their pleural fluid as compared to that of peripheral blood of the same patients, thus exhibiting localization of predominantly Th1-type immunity in the pleural fluid. On the contrary, patients with miliary TB had higher IFN-gamma levels in the peripheral blood as compared to their bronchoalveolar lavage fluid. Moreover, the median IFN-gamma: IL-4 ratio in the peripheral blood of miliary TB patients was two-fold higher as compared to bronchoalveolar lavage fluid, suggesting that the cytokine profile at the disease site is skewed toward a Th2-like bias. Further, flow cytometry data revealed a significantly higher (P < 0.001) percentage of CD4+ pleural fluid lymphocytes expressing IFN-gamma, whereas in the miliary TB, a nine-fold higher percentage of lymphocytes in bronchoalveolar lavage fluid expressed IL-4 in comparison with their peripheral CD4 T cells. Our data indicate, respectively, a Th1-like and Th2-like response in tuberculous pleural effusion and miliary TB, suggesting that these clinical forms of extrapulmonary tuberculosis probably reflect the extreme ends of a Th1-Th2 spectrum of the disease.

Evidence inconsistent with a negative influence of T helper 2 cells on protection afforded by a dominant T helper 1 response against Mycobacterium tuberculosis lung infection in mice

Mice incapable of generating an efficient Th2 response because of functional deletion of the genes for signal transducer and activation of transcription 6 (Stat6), interleukin-4 receptor alpha chain (IL-4Ralpha), or IL-4 plus IL-13 (IL-4/IL-13) were no more resistant than wild-type (WT) mice to airborne infection with virulent Mycobacterium tuberculosis. WT mice were able to control infection and hold it at a stationary level following 20 days of log linear M. tuberculosis growth. Likewise, infection was kept under control and was held at the same stationary level in IL-4/IL-13(-/-) mice but progressed to a slightly higher level in Stat6(-/-) and IL-4Ralpha(-/-) mice. The onset of stationary-level infection in WT mice was associated with the expression of Th1-mediated immunity, as evidenced by an approximately 100- to 1,000-fold increase in the lungs in the synthesis of mRNA for IL-12, gamma interferon (IFN-gamma), and inducible nitric oxide synthase (NOS2) that was sustained for at least 100 days. IL-12 is essential for the induction of Th1 immunity, IFN-gamma is a key Th1 cytokine involved in mediation of immunity, and NOS2 is an inducible enzyme of macrophages and is needed by these cells to express immunity. In response to infection, the lungs of Stat6(-/-) mice showed increases in synthesis of mRNA for IL-12, IFN-gamma, and NOS2 similar to that seen in WT mice. In IL-4/IL-13(-/-) mice, however, synthesis of mRNA for IFN-gamma and NOS2 reached higher levels than in WT mice. These results argue against the notion that a Th2 response is partly or wholly responsible for the inability of Th1-mediated immunity to resolve infection with a virulent strain of M. tuberculosis.

Shifts of T4/T8 T lymphocytes from BAL fluid and peripheral blood by clinical grade in patients with pulmonary tuberculosis

OBJECTIVES

We investigated the shifts of T4/T8 lymphocytes from BAL fluid (BALF) and peripheral blood by the clinical grade of pulmonary tuberculosis (TB), which is determined by factors such as extent of pulmonary involvement, fever, and loss of body weight.

MATERIALS AND METHODS

In order to explore these questions, BALF was collected from 45 patients presenting with active pulmonary TB and 14 healthy control subjects. The percentages for T-lymphocyte subpopulations, including CD4(+), CD8(+), and CD3(+) T cells, were measured using two-color flow cytometry.

RESULTS

A higher percentage of CD3(+)CD4(+) T lymphocytes, with a relatively lower percentage of CD3(+)CD8(+) T lymphocytes, was revealed for the patients with a higher grade of pulmonary TB, compared to patients with a lower grade of pulmonary TB, resulting in an increased BALF C4(+)/CD8(+) ratio. By contrast, a higher percentage of CD3(+)CD8(+) T lymphocytes with a relatively low percentage of CD3(+)CD4(+) T lymphocytes was demonstrated for these patients with a higher grade of pulmonary TB, resulting in a decreased peripheral blood CD4(+)/CD8(+) ratio.

CONCLUSIONS

Our findings suggest that compartmentalization of the CD4(+) T lymphocytes in the infected lungs may occur for patients with higher grades of pulmonary TB.

Elevated levels of serum macrophage migration inhibitory factor in patients with pulmonary tuberculosis

Macrophage migration inhibitory factor (MIF) was originally described as a T-cell-derived cytokine that inhibits the random migration of macrophages and promotes the delayed-type hypersensitivity reaction. MIF plays an important role in the regulation of the Th1/Th2 balance in inflammatory response. This study investigated serum levels of circulating MIF in patients with pulmonary tuberculosis. The levels of MIF in sera were measured by enzyme-linked immunosorbent assay in 34 patients with pulmonary tuberculosis (16 males and 18 females) and 30 healthy controls (15 males and 15 females). The mean levels of circulating MIF values were significantly higher in those with pulmonary tuberculosis (19.84 +/- 11.27 ng/ml; P < 0.0001) than in the healthy controls (4.38 +/- 1.34 ng/ml). Circulating MIF values significantly correlated with circulating interferon-gamma values (r = 0.537, P < 0.0001). Thus, MIF may play an important role in immune responses to human infection with Mycobacterium tuberculosis.

Correlation of ESAT-6-specific gamma interferon production with pathology in cattle following Mycobacterium bovis BCG vaccination against experimental bovine tuberculosis

Vaccine development and the understanding of the pathology of bovine tuberculosis in cattle would be greatly facilitated by the definition of immunological correlates of protection and/or pathology. To address these questions, cattle were vaccinated with Mycobacterium bovis bacillus Calmette-Guérin (BCG) and were then challenged with virulent M. bovis. Applying a semiquantitative pathology-scoring system, we were able to demonstrate that BCG vaccination imparted significant protection by reducing the disease severity on average by 75%. Analysis of cellular immune responses following M. bovis challenge demonstrated that proliferative T-cell and gamma interferon (IFN-gamma) responses towards the M. bovis-specific antigen ESAT-6, whose gene is absent from BCG, were generally low in vaccinated animals but were high in all nonvaccinated calves. Importantly, the amount of ESAT-6-specific IFN-gamma measured by enzyme-linked immunosorbent assay after M. bovis challenge, but not the frequency of responding cells, correlated positively with the degree of pathology found 18 weeks after infection. Diagnostic reagents based on antigens not present in BCG, like ESAT-6 and CFP-10, were still able to distinguish BCG-vaccinated, diseased animals from BCG-vaccinated animals without signs of disease. In summary, our results suggest that the determination of ESAT-6-specific IFN-gamma, while not a direct correlate of protection, constitutes nevertheless a useful prognostic immunological marker predicting both vaccine efficacy and disease severity.

Innate immunity to Mycobacterium tuberculosis

The different manifestations of infection with Mycobacterium tuberculosis reflect the balance between the bacillus and host defense mechanisms. Traditionally, protective immunity to tuberculosis has been ascribed to T-cell-mediated immunity, with CD4(+) T cells playing a crucial role. Recent immunological and genetic studies support the long-standing notion that innate immunity is also relevant in tuberculosis. In this review, emphasis is on these natural, innate host defense mechanisms, referring to experimental data (e.g., studies in gene knockout mice) and epidemiological, immunological, and genetic studies in human tuberculosis. The first step in the innate host defense is cellular uptake of M. tuberculosis, which involves different cellular receptors and humoral factors. Toll-like receptors seem to play a crucial role in immune recognition of M. tuberculosis, which is the next step. The subsequent inflammatory response is regulated by production of pro- and anti-inflammatory cytokines and chemokines. Different natural effector mechanisms for killing of M. tuberculosis have now been identified. Finally, the innate host response is necessary for induction of adaptive immunity to M. tuberculosis. These basic mechanisms augment our understanding of disease pathogenesis and clinical course and will be of help in designing adjunctive treatment strategies.

Expression of IL-15 in inflammatory pulmonary diseases

BACKGROUND

IL-15 is a T(H)1-related cytokine that shares many biologic activities with IL-2. Both cytokines bind a specific alpha subunit, and they share the same beta and gamma common receptor subunits for signal transduction. IL-15 has recently been shown to be upregulated in T cell-mediated inflammatory disorders, such as rheumatoid arthritis and inflammatory bowel diseases. However, the role and expression of IL-15 in inflammatory lung disease has not been investigated.

OBJECTIVE

In the present study we have evaluated the expression of IL-15 mRNA and protein in bronchial biopsy specimens obtained from patients with sarcoidosis (n = 8), tuberculosis (n = 7), chronic bronchitis (n = 10), and bronchial asthma (n = 8) and compared its expression with that seen in normal control subjects (n = 11).

METHODS

In situ hybridization and immunocytochemistry were used to detect the number of cells expressing IL-15 mRNA and protein, respectively, within sections of bronchial tissues from all subject groups. In addition, double immunocytochemistry was used to characterize the cellular source of IL-15.

RESULTS

The number of IL-15(+) cells was significantly higher within tissue from patients with sarcoidosis, tuberculosis, and chronic bronchitis compared with that in asthmatic patients and normal control subjects. Similar results were obtained for IL-15 immunoreactivity by using immunohistochemistry. Furthermore, double immunostaining revealed that neutrophils and macrophages are the major source of IL-15.

CONCLUSION

These results suggest that the expression of IL-15 may be associated with T(H)1-mediated chronic inflammatory diseases of the lung.

Association of interleukin-10 cytokine expression status with HLA non-DRB1*02 and Mycobacterium bovis BCG scar-negative status in south Indian pulmonary tuberculosis patients

HLA DRB1*02 and its subtypes predispose individuals for a far-advanced sputum-positive pulmonary tuberculosis transcending ethnic boundaries. Mycobacterium bovis BCG does not afford the desired protection against adult pulmonary tuberculosis, and a spectrum of immune reactivity exists in controls and hospital contacts. All of these findings have been identified and demonstrated in areas of endemicity. Skewing of immunity from protective to pathogenic may involve a shift in the Th1-Th2 paradigm. To elaborate these ideas, we studied gamma interferon (IFN-gamma), interleukin-4 (IL-4), and IL-10 cytokine expression in 71 adult pulmonary tuberculosis patients and 74 controls from areas of endemicity in south India by 48-h microculture and reverse transcription-PCR. Most of the patients and controls expressed IFN-gamma de novo, and in the presence of purified protein derivative (PPD), all of them expressed significantly higher levels of IFN-gamma, suggesting a PPD-specific recall memory. HLA DRB1* allele-dependent IFN-gamma expression was identified only in controls, suggesting a skewing of the immune response in patients. In contrast to the case for IFN-gamma, only some patients and controls expressed IL-4 or IL-10 (Th2 profile); thus, the Th1 profile was identifiable only by a nonexpression of IL-4 or IL-10 in this area of endemicity. The Th2 profile was associated with HLA non-DRB1*02 and BCG scar-negative status in patients, attributing a significant risk (odds ratio = 2.074; 95% confidence interval = 0.612 to 7.07). It is possible that Mycobacterium tuberculosis (PPD)-specific IL-10 is expressed preemptively in unvaccinated (BCG scar-negative) individuals with a non-DR2 genetic background by chronic exposure in this area of endemicity and leads to pulmonary tuberculosis of adults.