IFN-γ and IgA against non-methylated heparin-binding hemagglutinin as markers of protective immunity and latent tuberculosis: Results of a longitudinal study from an endemic setting

Lung cancer induced by Benzo(A)Pyrene: ChemoProtective effect of sinapic acid in swiss albino mice

Cancer of lung is the utmost typical cause of death and the number of cases is increasing rapidly, which has emerged as a major leading health problem. A large amount of reports suggested that Benzo(a)pyrene [B(a)P] in cigarette smoke plays the major function in an initiation of cancer of lung. Cancer prevention or chemoprevention has become a compelling approach recently for treatment of lung cancer. So, discovering a fresh candidate with reduced toxicity for targeting lung cancer is vital and urgent. Sinapic acid which is a widely extracted in various vegetables and fruit exhibits rich anti-oxidant content, anti-inflammatory and anti-tumor activity. But, the chemopreventive action of sinapic acid against lung cancer initiated by B[a]P remain unclear. Following, an in-vivo B[a]P-stimulated lung cancer in swiss albino mice and an in-vitro human lung cancer cell (A549) model were established to examine the chemopreventive activities of sinapic acid. The levels of immunoglobulins (IgG and IgM), oxidative and inflammatory markers, and tumor markers level was studied using kits and standard methods. The results showed administration of sinapic acid ameliorates the exposure of B[a]P mediated lung cancer in swiss albino mice by a decline in IgG and IgM level, leukocyte count, neutrophil function tests, soluble immune complex, lipid peroxidation, pro-inflammatory cytokines, tumor markers (AHH, LDH, GGT, 5'NT and CEA) and enhanced phagocytic index, activity index and antioxidant defense enzymes. In addition, in-vitro studies showed potential cytotoxicity against human lung cancer and exhibited a potential cytotoxic (MTT assay) and apoptotic activity by elevation of ROS production and caspase activity (caspase-3 and caspase-9). Collectively, the results, clearly specifies sinapic acid can be utilized as an effective chemo preventative agent against lung carcinogenesis.

Serum levels of inhibitory costimulatory molecules and correlations with levels of innate immune cytokines in patients with pulmonary tuberculosis

Objective

To analyze serum levels of inhibitory costimulatory molecules and their correlations with innate immune cytokine levels in patients with pulmonary tuberculosis (PTB).

Methods

Data for 280 PTB patients and 280 healthy individuals were collected. Serum levels of immune molecules were measured using ELISA. Univariate, multivariate, subgroup, matrix correlation, and receiver operating characteristic curve analyses were performed.

Results

Host, environment, lifestyle, clinical features, and medical history all influenced PTB. Serum levels of soluble programmed death ligand 1 (sPD-L1), soluble T-cell immunoglobulin- and mucin-domain–containing molecule 3 (sTim-3), soluble galectin-9 (sGal-9), interleukin (IL)-4, and IL-33 were significantly higher in patients with PTB, while levels of IL-12, IL-23, IL-18, and interferon (IFN)-γ were significantly lower. Serum levels of sTim-3 were higher in alcohol users. Levels of sTim-3 were negatively correlated with those of IL-12. Levels of IL-12, IL-23, and IL-18 were positively correlated with those of IFN-γ, while levels of IL-12 were negatively correlated with those of IL-4. The areas under the curve of sPD-L1, sTim-3, sGal-9, IL-12, IL-23, IL-18, IFN-γ, IL-4, and IL-33 for identifying PTB were all >0.77.

Conclusions

Inhibitory costimulatory molecules may be targets for controlling PTB. Immune molecules may be helpful for diagnosis of PTB.

B-Cells and Antibodies as Contributors to Effector Immune Responses in Tuberculosis

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), is still a major threat to mankind, urgently requiring improved vaccination and therapeutic strategies to reduce TB-disease burden. Most present vaccination strategies mainly aim to induce cell-mediated immunity (CMI), yet a series of independent studies has shown that B-cells and antibodies (Abs) may contribute significantly to reduce the mycobacterial burden. Although early studies using B-cell knock out animals did not support a major role for B-cells, more recent studies have provided new evidence that B-cells and Abs can contribute significantly to host defense against Mtb. B-cells and Abs exist in many different functional subsets, each equipped with unique functional properties. In this review, we will summarize current evidence on the contribution of B-cells and Abs to immunity toward Mtb, their potential utility as biomarkers, and their functional contribution to Mtb control.

Diagnostic Value of Recombinant Heparin-binding Hemagglutinin Adhesin Protein in Spinal Tuberculosis

Background and aim

To explore the diagnostic value of recombinant heparin-binding hemagglutinin adhesin (HBHA) protein antigen in spinal tuberculosis.

Materials and methods

Forty patients with spinal tuberculosis were included in the experimental group and 40 healthy people were included in the control group. Serum IgG antibody expression level was detected with recombinant HBHA protein as the antigen, using enzyme-linked immunosorbent assay (ELISA) detection.

Results

Patients with spinal tuberculosis and healthy volunteers were included in this study. A total of 40 eligible patients with spinal tuberculosis were included (24 males and 16 females, aged 18-72 years, with an average age of 41.24 ± 15.74 years). Forty healthy people were included (21 males and 19 females, aged 18-70 years, with an average age of 41.33 ± 12.36 years). On comparing the groups, no significant difference was found in the general data (P >0.05). IgG antibody level in the experimental group was higher than that in the control group, and the difference was significant (P < 0.00001).

Conclusions

Detection of serum HBHA protein antibody is of great value in the auxiliary diagnosis of spinal tuberculosis, and high HBHA expression can be used as an indicator for diagnosis of spinal tuberculosis.

Mycobacterium tuberculosis Primary Infection and Dissemination: A Critical Role for Alveolar Epithelial Cells

Globally, tuberculosis (TB) has reemerged as a major cause of morbidity and mortality, despite the use of the Mycobacterium bovis BCG vaccine and intensive attempts to improve upon BCG or develop new vaccines. Two lacunae in our understanding of the Mycobacterium tuberculosis (M. tb)-host pathogenesis have mitigated the vaccine efforts; the bacterial-host interaction that enables successful establishment of primary infection and the correlates of protection against TB. The vast majority of vaccine efforts are based on the premise that cell-mediated immunity (CMI) is the predominating mode of protection against TB. However, studies in animal models and in humans demonstrate that post-infection, a period of several weeks precedes the initiation of CMI during which the few inhaled bacteria replicate dramatically and disseminate systemically. The “Trojan Horse” mechanism, wherein M. tb is phagocytosed and transported across the alveolar barrier by infected alveolar macrophages has been long postulated as the sole, primary M. tb:host interaction. In the current review, we present evidence from our studies of transcriptional profiles of M. tb in sputum as it emerges from infectious patients where the bacteria are in a quiescent state, to its adaptations in alveolar epithelial cells where the bacteria transform to a highly replicative and invasive phenotype, to its maintenance of the invasive phenotype in whole blood to the downregulation of invasiveness upon infection of epithelial cells at an extrapulmonary site. Evidence for this alternative mode of infection and dissemination during primary infection is supported by in vivo, in vitro cell-based, and transcriptional studies from multiple investigators in recent years. The proposed alternative mechanism of primary infection and dissemination across the alveolar barrier parallels our understanding of infection and dissemination of other Gram-positive pathogens across their relevant mucosal barriers in that barrier-specific adhesins, toxins, and enzymes synergize to facilitate systemic establishment of infection prior to the emergence of CMI. Further exploration of this M. tb:non-phagocytic cell interaction can provide alternative approaches to vaccine design to prevent infection with M. tb and not only decrease clinical disease but also decrease the overwhelming reservoir of latent TB infection.

The Mycobacterial HBHA Protein: A Promising Biomarker for Tuberculosis

A major goal in tuberculosis (TB) research is the identification, among the subjects infected with Mycobacterium tuberculosis (Mtb), of those with active TB, or at higher risk of developing active disease, from the latently infected subjects. The classical heterogeneity of Mtb infection and TB disease is a major obstacle toward the identification of reliable biomarkers that can stratify Mtb infected subjects based on disease risk. The heparin-binding haemagglutinin (HBHA) is a mycobacterial surface antigen that is implicated in tuberculosis (TB) pathogenesis. The host immune response against HBHA varies depending on the TB status and several studies are supporting the role of HBHA as a useful biomarker of TB.

Synergy between Th1 and Th2 responses during Mycobacterium tuberculosis infection: A review of current understanding

Induction of Th1 (cell-mediated) immunity and associated production of IFN-γ by CD4+ T cells has been widely used as a marker of protective immunity against tuberculosis (TB). This is based on two assumptions. The first is the widely accepted view that Mycobacterium tuberculosis (Mtb), the causative agent of TB is an obligate intracellular pathogen, and the second is based on the Th1/Th2 paradigm, which posits that polarization of CD4+ T cells into type1 (cell-mediated) and type 2 (humoral) is central for proper induction of protective immunity against pathogens. However, almost all licensed vaccines currently in use are primarily anti-body based whether intracellular or extra-cellular. In addition, converging data from both animal models and humans indicate that the production of IFN-γ alone is not sufficient to confer protection against TB. In addition, a substantial body of the literature suggests that, in addition to Th1 cells, antibody classes and sub-classes are protective against TB. In a recent study, we have shown that there is a synergy between IFN-γ (cell-mediated) and IgA (humoral) in human population in an endemic setting. In this review, current data from both animal and human studies that support mixed Th1 and Th2 responses that are protective against Mtb and other pathogens are presented.

Development of tuberculosis vaccines in clinical trials: Current status

Tuberculosis (TB) is an important infectious disease worldwide. Currently, Bacillus Calmette-Guérin (BCG) remains the only TB vaccine licensed for human use. This TB vaccine is effective in protecting children against severe military TB but offers variable protective efficacy in adults. Therefore, new vaccines against TB are needed to overcome this serious disease. At present, around 14 TB vaccine candidates are in different phases of clinical trials. These TB vaccines in clinical evaluation can be classified into two groups including preventive pre- and post-exposure vaccines: subunit vaccines (attenuated viral vectors or adjuvanted fusion proteins), and whole-cell vaccines (genetically attenuated Mycobacterium tuberculosis (M. tb), recombinant BCG, killed M. tb or M. vaccae). Although, over the last two decades a great progress in the search for a more effective TB vaccine has been demonstrated there is still no replacement for the licensed BCG vaccine. This article summarizes the current status of TB vaccine development and identifies crucial gaps of research for the development of an effective TB vaccine in all age groups.

Progress and challenges in TB vaccine development

The Bacille Calmette Guerin (BCG) vaccine can provide decades of protection against tuberculosis (TB) disease, and although imperfect, BCG is proof that vaccine mediated protection against TB is a possibility. A new TB vaccine is, therefore, an inevitability; the question is how long will it take us to get there? We have made substantial progress in the development of vaccine platforms, in the identification of antigens and of immune correlates of risk of TB disease. We have also standardized animal models to enable head-to-head comparison and selection of candidate TB vaccines for further development.  To extend our understanding of the safety and immunogenicity of TB vaccines we have performed experimental medicine studies to explore route of administration and have begun to develop controlled human infection models. Driven by a desire to reduce the length and cost of human efficacy trials we have applied novel approaches to later stage clinical development, exploring alternative clinical endpoints to prevention of disease outcomes. Here, global leaders in TB vaccine development discuss the progress made and the challenges that remain. What emerges is that, despite scientific progress, few vaccine candidates have entered clinical trials in the last 5 years and few vaccines in clinical trials have progressed to efficacy trials. Crucially, we have undervalued the knowledge gained from our "failed" trials and fostered a culture of risk aversion that has limited new funding for clinical TB vaccine development. The unintended consequence of this abundance of caution is lack of diversity of new TB vaccine candidates and stagnation of the clinical pipeline. We have a variety of new vaccine platform technologies, mycobacterial antigens and animal and human models.  However, we will not encourage progression of vaccine candidates into clinical trials unless we evaluate and embrace risk in pursuit of vaccine development.

L. M. C. F, Ottenhoff THM. IgA and IgG against Mycobacterium tuberculosis Rv2031 discriminate between pulmonary tuberculosis patients, Mycobacterium tuberculosis-infected and non-infected individuals

As part of a major project to investigate protective and diagnostic immune markers against tuberculosis (TB), we measured antibody isotype responses to Mycobacterium tuberculosis (Mtb) antigens (LAM, Rv2031, and HBHA) in cohorts of 149 pulmonary tuberculosis patients (PTBP), 148 household contacts (HHCs), and 68 community controls (CCs) in an endemic setting. ELISA was used to measure levels of IgA, IgG, and IgM from sera of cohorts at baseline, and at 6 and 12 months from entry. The results show that there were significant differences in IgA, IgG, and IgM responses to the different antigens and in the three cohorts. At baseline, the level of IgM against RV2031 and LAM did not vary between cohorts, but the levels of IgA and IgG against Rv2031 were significantly higher in PTB patients than HHCs and CCs, followed by HHCs, and the lowest in CCs. In patients, there was a significant variation in antibody responses before and after chemotherapy. The levels of IgA and IgG against HBHA, and IgA against Rv2031 decreased significantly and remained low, while IgA and IgG against LAM increased significantly and remained high following chemotherapy. However, the levels of IgM against Rv2031 and LAM increased at 6 months but decreased again at 12 months. IgM against HBHA did not show any significant variation before and after chemotherapy. Similarly, there were also significant variations in antibody responses in HHCs over time. Our results show that there are significant variations in IgA, IgG and IgM responses to the different antigens and in the three cohorts, implying that not all antibody isotype responses are markers of clinical TB. In addition, the current and previous studies consistently show that IgA and IgG against Rv2031 discriminate between clinical disease, Mtb-infected and non-infected individuals.

IFN-γ against the 38-kDa antigen of Mycobacterium tuberculosis discriminates pulmonary tuberculosis from infection and infection from exposure: evidence from a study of human population in a high endemic setting

Mycobacterium tuberculosis (Mtb) 38-kDa antigen is an immunogenic lipoprotein that induces strong T-cell responses in experimental animals. However, there is limited information on the role of this antigen in human population. In this article, we present the dynamics of pro-inflammatory (IFN-γ and TNF-α) and anti-inflammatory cytokine (IL-10) against the 38 kDa in cohorts of pulmonary TB (PTB) patients, household contacts (HHCs), and community controls (CCs) in a high endemic setting. Whole blood assay was used to determine the levels of cytokines in 149 patients, 149 HHCs, and 68 CCs at baseline, 6 months, and 12 months. At baseline, the level of IFN-γ was significantly (p < 0.0001) higher in CCs and HHCs than in untreated patients. CCs had significantly (p < 0.05) higher level of IFN-γ than HHCs. There was no significant difference between treated and untreated patients, and there was no significant change in HHCs over 12 months. At baseline, the levels of IL-10 and TNF-α were significantly (p < 0.0001) higher in patients than in HHCs and CCs. No significant change was observed between treated patients and untreated patients and HHCs over time. The study shows that IFN-γ against the 38 kDa discriminates clinical TB from infection and infection from exposure, suggesting its potential for immune protection and diagnosis.

Immune characterization of the HBHA-specific response in Mycobacterium tuberculosis-infected patients with or without HIV infection

Introduction

RD1-based Interferon-γ Release Assays (IGRAs) cannot distinguish latent from active tuberculosis (TB) disease. Conversely, a positive response to heparin-binding haemagglutinin (HBHA)-based IGRAs, among TB-infected subjects, correlates with Mycobacterium tuberculosis (Mtb) containment and low risk of TB progression. The aim of this study was to characterize HBHA-immune responses in HIV-infected and uninfected subjects with active TB or latent TB infection (LTBI).

Methods

49 subjects were prospectively enrolled: 22 HIV-uninfected (13 TB, 9 LTBI) and 27 HIV-infected (12 HIV-TB, 15 HIV-LTBI). Whole blood and peripheral blood mononuclear cells were stimulated with HBHA and RD1 antigens. Interferon (IFN)γ release was evaluated by ELISA whereas cytokine profile [IFNγ, tumor necrosis (TNF)α, interleukin (IL)2] and phenotype (CD45RA, CCR7) by flow cytometry.

Results

Among LTBI individuals, HBHA stimulation induced IFNγ release in all the HIV-uninfected, while, only 4/15 HIV-infected responded. Within the active TB, only 5/13 HIV-uninfected and 1/12 HIV-TB patients responded. Interestingly, by cytometry we showed that CD4⁺ T-cells response to HBHA was significantly impaired in the HIV-infected subjects with TB or LTBI compared to the HIV-uninfected subjects. The phenotype of HBHA-specific CD4 T-cells showed a predominantly central memory (CM) and effector memory (EM) phenotype without differences among the groups. Differently, HBHA-specific CD8⁺ T-cells, showed mainly a CM and naïve phenotype in LTBI group while TB, HIV-LTBI and HIV-TB groups were characterized by EM or terminally differentiated phenotypes. Interestingly, differently than what observed for RD1, the cytokine profile of HBHA-specific T-cells evaluated by cytometry showed that the CD4⁺ T-cells were mostly monofunctional. Conversely, CD8-specific T-cells were mostly monofunctional for both HBHA and RD1 stimulations.

Conclusions

These results characterize the impact of HIV infection in CD4- and CD8-specific response to HBHA in both LTBI and TB patients. HIV infection impairs the CD4 response to HBHA and likely this may lead to an impairment of TB control.

Lack of Response to HBHA in HIV-Infected Patients with Latent Tuberculosis Infection

Heparin-binding haemagglutinin (HBHA) has been proposed as an immunological biomarker for discriminating active tuberculosis (TB) from latent TB infection (LTBI) and to identify those at higher risk of progressing to active disease. Few data are available in immune-compromised patients, which are those with increased risk of TB reactivation. The aim of this stusy was to evaluate the immune response to HBHA in HIV-infected subjects with LTBI (HIV-LTBI) or active TB (HIV-TB) in comparison with the immune response to additional Mycobacterium tuberculosis (Mtb) or HIV and CMV antigens. The responses are evaluated in relation to TB status and in the LTBI subjects with the progression to active TB within 2 years. Forty-one HIV-infected antiretroviral-naïve subjects were prospectively enrolled: 18 were HIV-TB and 23 HIV-LTBI. Whole blood was in vitro stimulated overnight with several antigens and mitogen. Interferon-γ response in the harvested plasma was evaluated by ELISA. Despite that CD4 cell count was significantly different between HIV-LTBI and HIV-TB, no differences were observed in response to Mtb- or HIV-specific antigens. Differently, low responses to HBHA were observed in both HIV-LTBI and HIV-TB subjects. Importantly, none of the six HIV-LTBI responding to HBHA developed TB, while two of 17 non-HBHA responders developed active disease. HIV-TB-coinfected subjects, regardless of their TB status, showed low responses to HBHA despite maintaining detectable responses to other antigens; moreover, among the HIV-LTBI, the lack of HBHA responses indicated an increased risk to develop active TB. These results, although preliminary, suggest that a positive response to HBHA in HIV-LTBI correlates with Mtb containment.