In vitro levels of cytokines in response to purified protein derivative (PPD) antigen in a population with high prevalence of pulmonary tuberculosis

Transcriptional Profiling of Human Peripheral Blood Mononuclear Cells Identifies Diagnostic Biomarkers That Distinguish Active and Latent Tuberculosis

Mycobacterium tuberculosis (M. tuberculosis) infection in humans can cause active disease or latent infection. However, the factors contributing to the maintenance of latent infection vs. disease progression are poorly understood. In this study, we used a genome-wide RNA sequencing (RNA-seq) approach to identify host factors associated with M. tuberculosis infection status and a novel gene signature that can distinguish active disease from latent infection. By RNA-seq, we characterized transcriptional differences in purified protein derivative (PPD)-stimulated peripheral blood mononuclear cells (PBMCs) among three groups: patients with active tuberculosis (ATB), individuals with latent TB infection (LTBI), and TB-uninfected controls (CON). A total of 401 differentially expressed genes enabled grouping of individuals into three clusters. A validation study by quantitative real-time PCR (qRT-PCR) confirmed the differential expression of TNFRSF10C, IFNG, PGM5, EBF3, and A2ML1 between the ATB and LTBI groups. Additional clinical validation was performed to evaluate the diagnostic performance of these five biomarkers using 130 subjects. The 3-gene signature set of TNFRSF10C, EBF3, and A2ML1 enabled correct classification of 91.5% of individuals, with a high sensitivity of 86.2% and specificity of 94.9%. Diagnostic performance of the 3-gene signature set was validated using a clinical cohort of 147 subjects with suspected ATB. The sensitivity and specificity of the 3-gene set for ATB were 82.4 and 92.4%, respectively. In conclusion, we detected distinct gene expression patterns in PBMCs stimulated by PPD depending on the status of M. tuberculosis infection. Furthermore, we identified a 3-gene signature set that could distinguish ATB from LTBI, which may facilitate rapid diagnosis and treatment for more effective disease control.

Differed IL-1 Beta Response between Active TB and LTBI Cases by Ex Vivo Stimulation of Human Monocyte-Derived Macrophage with TB-Specific Antigen

Background

The difference of macrophage-specific interleukin-1 beta (IL-1b) response between latent tuberculosis infection (LTBI) and active tuberculosis (TB) remains less studied.

Method

We performed this prospective study and recruited active TB patients, contacts with LTBI, and uninfected contacts. The gene and protein expression of human monocyte-derived macrophage (hMDM) after ex vivo stimulation by early secretory antigenic target-6KD (ESAT-6) and tuberculin purified protein derivatives (PPD) was studied by real-time PCR and flow cytometry. The effect of caspase-1 inhibitor was also studied.

Result

The IL-1b gene expression after 6 hr ESAT-6 1 μg/ml stimulation was different among active TB patients (n = 12), LTBI cases (n = 12), and uninfected contacts (n = 23) (log fold change: 0.98 ± 1.26 vs. 2.20 ± 0.96 vs. 2.20 ± 0.96, P = 0.013). The IL-1b gene expression at 24 hours was higher than that at 6 hours in LTBI cases (n = 4) and uninfected contacts (n = 6). After 24 hr ESAT-6 1 μg/ml stimulation, the percentage of IL-1b-expressed hMDM was borderline lower in the active TB patients (n = 9) than in the LTBI cases (n = 10) (14.0 ± 11.2% vs. 31.6 ± 22.5%, P = 0.065). Compared with ESAT-6 1 μg/ml stimulation but without the addition of caspase-1 inhibitor (CasI) (55.6 ± 16.3%), the percentage of IL-1b-positive hMDMs decreased after addition of CasI (50 μg/ml CasI: 49.8 ± 18.2%, P = 0.078; 100 μg/ml CasI: 46.6 ± 20.8%, P = 0.030; 150 μg/ml CasI: 33.7 ± 15.5%, P = 0.016).

Conclusions

This study revealed that macrophage-specific IL-1b response differed among different stages of Mycobacterium tuberculosis infection. The role of IL-1b and inflammasome in the process of LTBI progressing to active TB warrants further investigation.

Evaluation of the transcriptional immune biomarkers in peripheral blood from Warao indigenous associate with the infection by Mycobacterium tuberculosis

INTRODUCTION

Biomarkers are critical tools for finding new approaches for controlling the spread of tuberculosis (TB), including for predicting the development of TB therapeutics, vaccines, and diagnostic tools.

METHODS

Expression of immune biomarkers was analyzed in peripheral blood cells stimulated and non-stimulated with M. tuberculosis antigens ESAT-6, CFP10 and TB7.7. in Warao indigenous individuals. These biomarkers may be able to differentiate TB states, such as active tuberculosis (ATB) cases and latent tuberculosis infection (LTBI) from non-infected controls (NIC). A real-time reverse transcription polymerase chain reaction (RT-qPCR) assay was performed on 100 blood samples under non-stimulation or direct ex vivo conditions (NS=50) and stimulation conditions (S=50).

RESULTS

The findings are shown as the median and interquartile range (IQR) of relative gene expression levels of IFN-γ, CD14, MMP9, CCR5, CCL11, CXCL9/MIG, and uPAR/PLAUR immune biomarkers. MMP9 levels were significantly higher in the LTBI-NS and LTBI-S groups compared with the NIC-NS and NIC-S groups. However, CCR5 levels were significantly lower in the LTBI-S group compared with both NIC-NS and NIC-S groups. CCL11 levels were significantly lower in the LTBI-S group compared with the NIC-NS group.

CONCLUSIONS

Preliminary findings showed that MMP9 immune biomarkers separated LTBI indigenous individuals from NIC indigenous individuals, while CCR5, CCL11, CD14, and IFN-γ did not differentiate TB states from NIC. MMP9 may be useful as a potential biomarker for LTBI and new infected case detection among Warao indigenous individuals at high risk of developing the disease. It may also be used to halt the epidemic, which will require further validation in larger studies.

Multiple cytokine responses in discriminating between active tuberculosis and latent tuberculosis infection

BACKGROUND

Cytokines play an important role in cell-mediated immune responses against Mycobacterium tuberculosis (Mtb) infection. Cytokine profile specifically associated with active tuberculosis (ATB) patients, subjects with latent tuberculosis infection (LTBI) and non-infected individuals remains to be determined.

METHODS

We enrolled a total of 92 subjects including patients with ATB (n = 25), LTBI (n = 36) and healthy controls (HC, n = 31) to investigate the cytokine production by peripheral blood mononuclear cells after Mtb purified protein derivative (PPD) stimulation which was evaluated by a beads-based multiplex assay system.

RESULTS

The production of IL-1β, IL-2, IL-6, IL-10, IL-17, G-CSF, IFN-γ, IP-10, MIP-1α and TNF-α was abundantly induced by PPD in all three groups. The levels of IL-2, IL-10, IFN-γ, IP-10 and TNF-α were significantly higher in LTBI group than in ATB group. The combination of PPD-stimulated IL-2 and IL-10 accurately identified 84.0% of ATB and 88.9% of LTBI. We validated the use of PPD-stimulated IL-2 and IL-10 test combined with T-SPOT.TB test in a cohort of 44 subjects with TB suspicion. The sensitivity and specificity of the combined test were 83.3% and 92.3%, respectively. The PPD-stimulated IL-2/IFN-γ ratio (p < 0.001) in LTBI subjects was significantly higher than in active TB patients.

CONCLUSION

Our study identified cytokine patterns characteristic of ATB and LTBI. Cytokines such as IL-2 and IL-10 may serve as biomarkers for distinguishing ATB from LTBI and healthy control and may contribute to intervention and improvement in TB diagnosis.

Monocyte-derived IL-5 reduces TNF production by Mycobacterium tuberculosis-specific CD4 T cells during SIV/M. tuberculosis coinfection

HIV-infected individuals are significantly more susceptible to tuberculosis (TB) than uninfected individuals. Although it is established that HIV reduces Mycobacterium tuberculosis-specific T cell responses, the causes of this dysfunction are not known. We used the cynomolgus macaque model of TB to demonstrate that ex vivo SIV reduces the frequency of M. tuberculosis-specific TNF and IFN-γ-producing T cells within 24 h after infection. In vivo, T cell IFN-γ responses in granulomas from animals with SIV/M. tuberculosis coinfection were lower than SIV-negative animals with active TB. The SIV effects on the inhibition of T cell responses were primarily on APCs and not the T cells directly. Specifically, reductions in the frequency of TNF-producing M. tuberculosis-specific CD4 T cells were caused, at least in part, by SIV-induced production of monocyte derived IL-5.

Genetic polymorphism and immune response to tuberculosis in indigenous populations: a brief review

We systematically reviewed studies of the immune response to tuberculosis and the genetic polymorphisms associated with Th1- or Th2-mediated cytokine expression in indigenous populations. A bibliographic search was performed on the Medline and ISI databases and included studies published between January 1980 and October 2011. The search terms were tuberculosis, American Indians, Amerindian, indigenous, Indians, native people, aboriginal, immun*, host immune, immune response, cytokine*, polymorphism*, and gene. Regardless of their design, studies that evaluated immunoglobulin, cytokine levels and genetic polymorphisms that altered cytokine expression were included. Thirteen studies met the inclusion criteria. The majority of studies were performed in Latin America, and five investigated the Warao ethnic group of Venezuela. Most of the investigations indirectly evaluated the immune response. Higher anergy to the tuberculin skin test, higher IgG4 and IgM levels, higher IL-5 production and lower TNF-α, IL-12p40 and IFN-γ production were found in the indigenous populations. The studies also reported a predominantly Th2-type response in these populations and a possibly higher susceptibility to tuberculosis. A better understanding of the relevant genetic polymorphisms and their role in immune regulation would help to clarify the immunogenetic mechanisms of TB infection in these populations. This information would be useful for identifying new treatments and preventing infection and progression to active disease.

Helminths and skewed cytokine profiles increase tuberculin skin test positivity in Warao Amerindians

The immune regulatory mechanisms involved in the acquisition of Mycobacterium tuberculosis infection in children are largely unknown. We investigated the influence of parasitic infections, malnutrition and plasma cytokine profiles on tuberculin skin test (TST) positivity in Warao Amerindians in Venezuela. Pediatric household contacts of sputum smear-positive tuberculosis (TB) cases were enrolled for TST, chest radiograph, plasma cytokine analyses, QuantiFERON-TB Gold In-Tube (QFT-GIT) testing and stool examinations. Factors associated with TST positivity were studied using generalized estimation equations logistic regression models. Of the 141 asymptomatic contacts, 39% was TST-positive. After adjusting for age, gender and nutritional status, TST positivity was associated with Trichuris trichiura infections (OR 3.5, 95% CI 1.1-11.6) and low circulating levels of T helper 1 (Th1) cytokines (OR 0.51, 95% CI 0.33-0.79). Ascaris lumbricoides infections in interaction with Th2- and interleukin (IL)-10-dominated cytokine profiles were positively associated with TST positivity (OR 3.1, 95% CI 1.1-8.9 and OR 2.4, 95% CI 1.04-5.7, respectively). A negative correlation of QFT-GIT mitogen responses with Th1 and Th2 levels and a positive correlation with age were observed (all p < 0.01). We conclude that helminth infections and low Th1 cytokine plasma levels are significantly associated with TST positivity in indigenous Venezuelan pediatric TB contacts.

Patients exposed to Mycobacterium tuberculosis infection with a prominent IgE response

BACKGROUND AND AIMS

Even though it has been reported that chronic immune activation associated with intestinal helminthic infections results in a predominant IgE response, specific IgE antibodies that are also interleukin 4 (IL-4) dependent have been reported in tuberculosis patients; however, this fact has not been widely reported. This study was aimed at investigating the levels of circulating IgE in Warao (an indigenous population) of the Orinoco river delta, an area isolated from contact with the tubercle bacillus for millennia until the mid-1960s as compared to Creole (nonindigenous population).

METHODS

A total of 294 individuals were studied, 161 Warao and 136 Creole. Patient group was comprised of 86 Warao patients (WP) and 60 Creole patients (CP). Control group was comprised of 75 Warao controls (WC) and 76 Creole controls (CC). Total serum IgE and IgE and IgG(4) reactivities to M. tuberculosis antigens were measured by an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Levels of total serum IgE were significantly elevated in WP (13002.0 ± 11200.0 IU/mL) and WC (2763.5 ± 2596.2 IU/mL) than in CP (385.9 ± 155.1 IU/mL) and CC (356.6 ± 157.5 IU/mL) (p <0.0001). Anti-PPD and anti-H37Rv IgE were significantly higher in WP (0.240 ± 0.145 and 0.230 ± 0.155) than in CP (0.127 ± 0.152 and 0.97 ± 0.103, respectively) and also between WC (0.240 ± 0.273 and 0.147 ± 0.158) and CC (0.115 ± 0.136 and 0.43 ± 0.46, respectively) (p <0.0001). Anti-PPD and anti-H37Rv IgG(4) did not show differences among groups; however, anti-H37Rv IgG(4) was affected by anti-TB treatment, which could be predictive of treatment outcome.

CONCLUSIONS

The findings suggest that for the Warao population there is an intrinsic propensity to produce a high IgE response, which could be incompatible with the protective response to M. tuberculosis.