DosR regulon genes are considered essential for Mycobacterium tuberculosis dormancy, and their products are demonstrated to have immunogenicity in M. tuberculosis-infected individuals, suggesting that DosR regulon-encoded proteins are suitable targets for vaccines to control the reactivation of dormant M. tuberculosis.Prospective analysis of T-cell and antibody responses against DosR regulon-encoded antigens in M. tuberculosis-infected individuals in Japan to identify effective vaccine targets.T-cell responses against 33 DosR regulon-encoded antigens were investigated in 26 consecutive M. tuberculosis-infected individuals-14 with latent tuberculosis infection (LTBI) and 12 with active pulmonary tuberculosis (PTB)-using enzyme-linked immunosorbent spot assay, and antibody responses in 42 consecutive individuals, 14 with LTBI and 28 with PTB.Six antigens (Rv0570, Rv1996, Rv2004c, Rv2028c, Rv2029c and Rv3133c) induced stronger T-cell responses in LTBI than in PTB, In contrast, antigen-specific antibody responses to five antigens (Rv0080, Rv1738, Rv2007c, Rv2031c and Rv2032) were found to be stronger in PTB than in LTBI cases.T-cell responses to six antigens might contribute to natural protection against dormant M. tuberculosis. These antigens are therefore considered to be potential targets of novel vaccines to control M. tuberculosis reactivation in the Japanese population.

Tuberculosis (TB) is associated with oxidative stress and the induction of host anti-oxidants to counteract this response. Heme oxygenase-1 (HO-1) is a critical promoter of cytoprotection in diverse disease models including mycobacterial infection. Nevertheless, the pattern of expression of HO-1 in human tuberculosis has not been studied. Here, we examine expression of HO-1 in M. tuberculosis-exposed and -infected individuals and test its ability to distinguish active from latent and successfully treated TB cases. In addition, we assess correlations between plasma levels of HO-1 and cytokines closely associated with the immunopathogenesis of TB.Cross-sectional and longitudinal analyses of levels of HO-1, acute phase proteins and pro-inflammatory cytokines were performed in plasma samples from individuals with active pulmonary, extra-pulmonary or latent TB infection and healthy controls as part of a prospective cohort study in South India.Systemic levels of HO-1 were dramatically increased in individuals with active pulmonary and extra-pulmonary tuberculosis and particularly those with bilateral lung lesions and elevated bacillary loads in sputum. HO-1 levels effectively discriminated active from latent tuberculosis with higher predictive values than either C-reactive protein or serum amyloid protein. Moreover, there was a marked reduction in HO-1 levels in active TB cases following anti-tuberculous therapy but not in those who failed treatment. Pulmonary TB patients displaying the highest concentrations of HO-1 in plasma exhibited significantly elevated plasma levels of interleukin (IL)-10, interferon (IFN)-γ and IL-17 and diminished levels of tumor necrosis factor (TNF)-α.These findings establish HO-1 levels as a potentially useful parameter for distinguishing active from latent or treated pulmonary tuberculosis, that is superior in this respect to the measurement of other acute inflammatory proteins.

Exposure to microbes may result in maternal immune responses that can affect fetal immune development. Several lines of evidence have shown that mycobacterial antigens can change the onset of atopic disease. We hypothesized that infants born to mothers with a positive tuberculosis (TB) test and a negative chest radiograph, may exhibit differential development of atopic disease during early childhood. The study was designed as a case control study. Birth records for infants born to untreated mothers with a positive TB skin test (TST), as defined by ≥10 mm induration were reviewed (n = 145 cases) and compared to a randomly selected unmatched control cohort of 46 women with a negative TST who delivered during the same time period at Scripps Hospital in San Diego, CA, USA. Childhood outcome parameters reviewed were: (1) the onset of physician diagnosed asthma; (2) lower respiratory tract infection (LRTI) with wheezing, latent tuberculosis infection/wheezing diagnosed on physical examination; (3) nonsurgical hospitalization; (4) atopic disease (eye/skin/nasal-sinus disease); (5) infections: ear, LRTI, sinus. LRTI was defined as an infection of the lower airways, eg, pneumonia. Outcomes at the end of years 1, 2, and 3-5 years combined were analyzed. Fisher exact test, Chi-square analysis or Poisson regression analysis were used as appropriate and a P-value of <0.05 was defined as significant. The cases and controls had similar birth weights, gestational ages, maternal ages: 3.34 versus 3.35 kg; 38.3 versus 39.2 weeks, 27.4 versus 26 years (P = non-significant). The childhood outcome parameters of the new onset of asthma was significantly higher than controls by age 2 years, but not at other ages studied, based on available clinic follow up data (P = 0.02). There was a difference in the risk for lung infection at age 2 and 3-5 years (P < 0.0001). There were no differences in the other outcome parameters studied (P = ns). There were no cases of infants with a positive TST, maternal Bacille Calmette-Guerin vaccination or active maternal TB, based on our study findings. There was a higher occurrence of asthma and lung infections at age 2 years among controls (P = 0.02). Our study defines for the first time a possible influence of maternal latent TB infection on fetal and childhood illness.

Dialysis patients are more likely than the general population to develop active tuberculosis (TB). In these patients, the availability of a highly sensitive and specific test to diagnose latent TB will ensure earlier treatment and decreased progression to active disease. In the current study, the Quanti-FERON-TB Gold In-Tube (QFT-G) test was compared with the tuberculin skin test (TST) for the diagnosis of latent tuberculosis infection (LTBI) among 200 hemodialysis patients and 15 confirmed TB disease cases in a tertiary care center in Saudi Arabia. Among the LTBI cases, 26 (13%) were TST positive, and 65 (32.5%) were positive by the QTF-G test, with an overall agreement between the 2 tests of 75.5% (k=0.34) being observed. Among the confirmed tuberculosis disease cases, none were positive by TST, and 10 (66.7%) were positive by the QTF-G test, resulting in an overall agreement of 33.3% (k=0). A comparison between the TST and the QTF-G test was performed based on the sensitivity, specificity, and area under the curve (AUC) obtained for the tests. The QTF-G test was more sensitive and less specific than the TST in predicting the confirmed TB disease cases. When we tested the correspondence of the AUC values between the 2 diagnostic modalities, the obtained p-value was 0.0003. In conclusion, the AUCs of the examined diagnostic modalities are significantly different in predicting LTBI and tuberculosis.

OBJECTIVES:

: Opiates drug users are at much higher risk of developing tuberculosis (TB) infection than general population. We conducted this study to determine the susceptibility for pulmonary and latent TB infection in opiates drug users.

METHODS::

In this cross-sectional study, all opiates drug users referred to drop-in centers, methadone maintenance clinics, and harm-reduction facilities affiliated with Shiraz University of Medical Sciences in southern Iran were screened for pulmonary and latent TB infection.

RESULTS::

The participation rate of opiate drug users was 87.66% (263 of 300). Mean age was 37.37 ± 8.33 (range, 20-65) years. Two hundred twenty-six (85.93%) were male and 197 (74.90%) were injection drug users (IDUs). One hundred sixty-three (61.97%) had TB-related symptoms. Culture for TB was positive in 3 patients (1.14%) (2 non-IDUs and 1 IDU). Two patients (0.76%) showed acid-fast bacilli in the direct sputum smear. Eighty-five of 244 patients (34.83%) had a 5- to 10-mm induration in the skin TB test. Twenty-nine of 223 patients (13%) had abnormal findings from chest x-ray films.

CONCLUSIONS::

The prevalence of smear-positive pulmonary TB in opiate drug users is more than 100 times in the general population in Iran. Therefore, active and appropriate screening to detect pulmonary TB infection should be integrated into routine activities at all harm-reduction facilities for drug users, irrespective of their route of drug use or human immunodeficiency virus status, in this country.

BACKGROUND:

Human tuberculosis caused by M. bovis is a zoonosis presently considered sporadic in developed countries, but remains a poorly studied problem in low and middle resource countries. The disease in humans is mainly attributed to unpasteurized dairy products consumption. However, transmission due to exposure of humans to infected animals has been also recognized. The prevalence of tuberculosis infection and associated risk factors have been insufficiently characterized among dairy farm workers (DFW) exposed in settings with poor control of bovine tuberculosis.

METHOD

OLOGY

PRINCIPAL FINDINGS:

Tuberculin skin test (TST) and Interferon-gamma release assay (IGRA) were administered to 311 dairy farm and abattoir workers and their household contacts linked to a dairy production and livestock facility in Mexico. Sputa of individuals with respiratory symptoms and samples from routine cattle necropsies were cultured for M. bovis and resulting spoligotypes were compared. The overall prevalence of latent tuberculosis infection (LTBI) was 76.2% (95% CI, 71.4-80.9%) by TST and 58.5% (95% CI, 53.0-64.0%) by IGRA. Occupational exposure was associated to TST (OR 2.72; 95% CI, 1.31-5.64) and IGRA (OR 2.38; 95% CI, 1.31-4.30) adjusting for relevant variables. Two subjects were diagnosed with pulmonary tuberculosis, both caused by M. bovis. In one case, the spoligotype was identical to a strain isolated from bovines.

CONCLUSIONS:

We documented a high prevalence of latent and pulmonary TB among workers exposed to cattle infected with M. bovis, and increased risk among those occupationally exposed in non-ventilated spaces. Interspecies transmission is frequent and represents an occupational hazard in this setting.

Rationale/objectives: There are hardly any data about the frequency of CD4+CD25+Foxp3+ve regulatory T cells (T-Regs) in the lungs of patients with active tuberculosis.

Methods:

Patients with pulmonary tuberculosis (TB; n=49) and healthy volunteers with presumed latent-TB infection (LTBI; n=38) donated blood and/or broncho-alveolar-lavage cells (BAL) obtained via bronchoscopy. T-cell phenotype (Th1/Th2/Th17/T-Reg) and functional status was evaluated using flow-cytometry and 3H-thymidine proliferation assays, respectively. H37Rv-infected alveolar and monocyte-derived macrophages were co-cultured with autologous T-Regs and PPD pre-primed T-Reg-depleted effector cells. Mycobacterial containment was evaluated by counting colony-forming units.

Results:

In blood and BAL T-Reg levels were higher in TB versus LTBI (p<0.04), and in TB the frequency of T-Regs was significantly higher in BAL versus blood (p<0.001). T-Reg-mediated suppression of T-cell proliferation in blood and BAL was concentration-dependent. Restriction of mycobacterial growth in infected alveolar and monocyte-derived macrophages was significantly diminished, and by up to 50%, when T-Regs were co-cultured with PPD-primed CD4+ effector T-cells. The levels of CD8+T-Regs (CD8+CD25+Foxp3+), IL-17-producing T-Regs (IL-17+CD4+CD25+Foxp3+), and IL-17-producing T-cells were similar in BAL-TB versus BAL-LTBI. Within the TB group compartmentalisation of responses was prominent (T-Reg, IFN-γ, TNF-α, IL17 and IL-22 significantly higher in BAL versus blood).

Conclusions:

In patients with TB the alveolar compartment is enriched for CD4+T-Regs. Peripheral blood-derived T-Regs decrease the ability of alveolar and monocyte-derived macrophages to restrict the growth of M. tb in the presence of effector cells. Collectively, these data suggest that CD4+CD25+FoxP3+ T-Regs subvert anti-mycobacterial immunity in human tuberculosis.

Biomarkers for active tuberculosis (TB) are urgently needed. Mycobacteria produce membrane vesicles (MVs) that contain concentrated immune-modulatory factors that are released into the host. We evaluated the human immune responses to BCG and Mycobacterium tuberculosis MVs to characterize the antibody responses and identify potentially novel TB biomarkers. Serological responses to MVs were evaluated by ELISAs and immunoblots with sera from 16 sputum smear-positive, 12 smear-negative HIV uninfected pulmonary TB patients and 16 BCG vaccinated Tuberculin skin-test positive controls with and without latent tuberculosis infection. MVs from both BCG and M. tuberculosis induced similar responses and were strongly immunogenic in TB patients but not in controls. Several MV-associated antigens appear to induce robust antibody responses, in particular the arabinomanan portion of the cell wall glycolipid lipoarabinomannan. Three proteins at ∼36, 25, and 23 kDa were simultaneously recognized by sera from 16/16 smear-positive, 9/12 smear-negative TB patients and 0/16 controls. These results provide promise and encouragement that antibody responses to proteins enriched in MVs of pathogenic mycobacteria may constitute a novel TB biomarker signature that could have diagnostic information.

The study demonstrates that in cattle, animals heterozygous at the MyD88 A625C polymorphic marker have a 5-fold reduced risk for active pulmonary tuberculosis (odds ratio [OR] = 0.19; P = 6 × 10(-12)). The reduced risk, however, does not extend to animals with latent pulmonary tuberculosis (OR = 0.83; P = 0.40). Heterozygosity at the A625C single nucleotide polymorphism is associated with intermediate levels of tumor necrosis factor alpha, gamma interferon, and nitric oxide synthase (NOS). Accordingly, deficiency as well as overexpression of proinflammatory cytokines or NOS favor tuberculosis, while heterozygosity provides the animals with the optimal level of inflammation.

Tuberculosis (TB) causes 1.45 million deaths annually world wide, the majority of which occur in the developing world. Active TB disease represents immune failure to control latent infection from airborne spread. Acid-fast bacillus (AFB) seen on sputum smear is a biomarker for contagiousness.We enrolled 73 tuberculosis patients with extensive infiltrates into a research study using bronchoalveolar lavage (BAL) to sample lung immune cells and assay BAL cell cytokine production. All patients had sputum culture demonstrating Mycobacterium tuberculosis and 59/73 (81%) had AFB identified by microscopy of the sputum. Compared with smear negative patients, smear positive patients at presentation had a higher proportion with smoking history, a higher proportion with temperature >38.5(0) C, higher BAL cells/ml, lower percent lymphocytes in BAL, higher IL-4 and IL-12p40 in BAL cell supernatants. There was no correlation between AFB smear and other BAL or serum cytokines. Increasing IL-4 was associated with BAL PMN and negatively associated with BAL lymphocytes. Each 10-fold increase in BAL IL-4 and IL-12p40 increased the odds of AFB smear positivity by 7.4 and 2.2-fold, respectively, in a multi-variable logistic model.Increasing IL-4 and IL-12p40 production by BAL cells are biomarkers for AFB in sputum of patients who present with radiographically advanced TB. They likely reflect less effective immune control of pathways for controlling TB, leading to patients with increased infectiousness.