Immunoregulation in TB: observations and implications

Low-dose M.tb infection but not BCG or MTBVAC vaccination enhances heterologous antibody titres in non-human primates

Introduction

Mycobacteria are known to exert a range of heterologous effects on the immune system. The mycobacteria-based Freund's Complete Adjuvant is a potent non-specific stimulator of the immune response used in immunization protocols promoting antibody production, and Mycobacterium bovis Bacille Calmette Guérin (BCG) vaccination has been linked with decreased morbidity and mortality beyond the specific protection it provides against tuberculosis (TB) in some populations and age groups. The role of heterologous antibodies in this phenomenon, if any, remains unclear and under-studied.

Methods

We set out to evaluate antibody responses to a range of unrelated pathogens following infection with Mycobacterium tuberculosis (M.tb) and vaccination with BCG or a candidate TB vaccine, MTBVAC, in non-human primates.

Results

We demonstrate a significant increase in the titer of antibodies against SARS-CoV-2, cytomegalovirus, Epstein-Barr virus, tetanus toxoid, and respiratory syncytial virus antigens following low-dose aerosol infection with M.tb. The magnitude of some of these responses correlated with TB disease severity. However, vaccination with BCG administered by the intradermal, intravenous or aerosol routes, or intradermal delivery of MTBVAC, did not increase antibody responses against unrelated pathogens.

Discussion

Our findings suggest that it is unlikely that heterologous antibodies contribute to the non-specific effects of these vaccines. The apparent dysregulation of B cell responses associated with TB disease warrants further investigation, with potential implications for risk of B cell cancers and novel therapeutic strategies.

An Unresolving Case of Pyomyositis: A Case Report

Pyomyositis which is also known as myositis tropicans is a rare condition where there is bacterial infection of the skeletal muscle. Its manifestation includes pain and tenderness of the affected muscle and general infective symptoms. It commonly occurs in immunocompromised individuals and patients with previous history of trauma to the affected muscle. We report a case of a 16-year-old boy with history of underlying bronchial asthma who presented with multiple abscesses. He underwent multiple operations to drain the infection and targeted antibiotic therapy subsequently. Despite undergoing surgical debridement, drainage and antibiotic treatment, he was still having repeated bouts of fever and his inflammatory markers were not reducing. He was then diagnosed with concurrent pulmonary tuberculosis infection which subjected him to an immunosuppressed state thus arising to the condition of pyomyositis and unresolving fever. The patient then made prompt improvement when the underlying cause of immunosuppression; pulmonary tuberculosis was treated as well.

Low body mass index is associated with diminished plasma cytokines and chemokines in both active and latent tuberculosis

Introduction

Low body mass index (BMI) is a major risk factor for tuberculosis (PTB). Low BMI can impair the immune system and thus might affect TB incidence.

Methods

We examined the plasma levels of Type 1, Type 17, pro-inflammatory, Type 2 and regulatory cytokines and CC and CXC chemokines in PTB and latent TB (LTB) individuals with low BMI (LBMI) or normal BMI (NBMI).

Results

Our data show that PTB is associated with significantly lower levels of IFNγ, TNFα, IL-2, IL-17A, IL-6, IL-12, IL-4 and IL-5 cytokines but significantly higher levels of IL-10, TGFβ and GM-CSF in LBMI compared to NBMI. Similarly, PTB is also associated with significantly lower levels of CCL2, CCL3, CCL11, CXCL1, CXCL9 and CXCL10 chemokines in LBMI compared to NBMI. Our data reveals that LTB is associated with significantly lower levels of IFNγ, TNFα, IL-2, IL1β, IL-12, IL-13 cytokines but significantly higher levels of IL-10, TGFβ, IL-4 and IL-22 in LBMI compared to NBMI. Similarly, LTB is also associated with significantly lower levels of CCL2, CXCL1, CXCL9 and CXCL10 and significantly higher levels of CCL1, CCL3, and CCL4 in LBMI compared to NBMI.

Conclusion

Thus, LBMI has a major impact on the cytokine and chemokine milieu of both PTB and LTB and might predispose to the increased risk of tuberculosis by this immunomodulatory effect.

The multi-faceted roles of TGF-β in regulation of immunity to infection

Transforming Growth Factor-β is a potent regulator of the immune system, acting at every stage from thymic differentiation, population of the periphery, control of responsiveness, tissue repair and generation of memory. It is therefore a central player in the immune response to infectious pathogens, but its contribution is often clouded by multiple roles acting on different cells in time and space. Hence, context is all-important in understanding when TGF-β is beneficial or detrimental to the outcome of infection. In this review, a full range of infectious agents from viruses to helminth parasites are explored within this framework, drawing contrasts and general conclusions about the importance of TGF-β in these diseases.

Enhanced Mycobacterial Antigen-Induced Pro-Inflammatory Cytokine Production in Lymph Node Tuberculosis

Lymph node tuberculosis (LNTB) is characterized by the enhanced baseline and antigen-specific production of type 1/17 cytokines and reduced baseline and antigen-specific production of interleukin (IL)-1β and IL-18 at the site of infection when compared with peripheral blood. However, the cytokine profile in the lymph nodes (LNs) of Mycobacterium tuberculosis culture-positive LNTB (LNTB+) and negative LNTB (LNTB-) has not been examined. To address this, we have examined the baseline and mycobacterial antigen-stimulated cytokine levels of type 1 (interferon gamma [IFNγ], tumor necrosis factor alpha [TNFα], IL-2), type 2 (IL-4, IL-5, and IL-13), type 17 (IL-17A, IL-17F, and IL-22), pro-inflammatory (IL-1α, IL-1β, IL-18, and granulocyte macrophage colony-stimulating factor [GM-CSF]), and regulatory cytokines (IL-10, transforming growth factor beta [TGF-β]) cytokines in the LN culture supernatants of LNTB+ and LNTB- individuals. We have observed significantly enhanced baseline levels of IL-13 and IL-10 and significantly reduced baseline levels of IL-4 and GM-CSF in LNTB+ individuals compared with LNTB- individuals. By contrast, we have observed significantly enhanced levels of type 1 (IFNγ, TNFα, and IL-2), type 17 (IL-17F and IL-22), and pro-inflammatory (IL-1α and GM-CSF) cytokines and significantly reduced levels of TGFβ in response to purified protein derivative, early secreted antigen-6, and culture filtrate protein-10 antigens in LNTB+ compared with LNTB- individuals. On phorbol 12-myristate 13-acetate/ionomycin stimulation, no significant difference was observed for any of the cytokines examined. Thus, our study revealed several interesting differences in the cytokine profiles of mycobacterial antigen-stimulated LN cultures in LNTB+ and LNTB- individuals. Therefore, we suggest the presence of mycobacteria plays a significant role in driving the cytokine response at the site of infection in LNTB.

Helminth mediated modulation of the systemic and mycobacterial antigen - stimulated cytokine profiles in extra-pulmonary tuberculosis

Background

Helminth infections are known to regulate cytokine responses in both pulmonary and latent tuberculosis infection. Whether helminth infections also modulate cytokine responses in extra-pulmonary tuberculosis, specifically tuberculous lymphadenitis (TBL), has not been examined thus far.

Methodology

Hence, to determine the cytokine profile in helminth-TBL coinfection, we measured the systemic and mycobacterial (TB)–antigen stimulated levels of Type 1, Type 2, Type 17, regulatory and pro-inflammatory cytokines in TBL individuals coinfected with or without Strongyloides stercoralis (Ss) infection.

Significant findings

TBL-Ss+ individuals have significantly higher bacterial burdens in the affected lymph nodes in comparison to TBL-Ss- individuals. TBL-Ss+ individuals exhibit significantly enhanced plasma levels of Type 2 (IL-5 and IL-13), Type 17 (IL-17 and IL-22) and regulatory (IL-10) cytokines in comparison to TBL-Ss- individuals. In contrast, TBL-Ss+ individuals exhibit significantly diminished plasma levels of pro-inflammatory cytokines (IL-1α and GM-CSF) in comparison to TBL-Ss- individuals. TBL-Ss+ individuals also exhibit significantly diminished unstimulated or mycobacterial—antigen stimulated levels of Type 1, Type 17 or IL-1 family cytokines in comparison to TBL-Ss- individuals but no differences in mitogen stimulated cytokine levels.

Conclusion

Therefore, our data reveal a profound influence of Ss infection on the bacteriological profile of TBL and suggesting that the underlying modulation of cytokine responses might be a mechanism by which this helminth infection could impart a detrimental effect on the pathogenesis of TBL disease.

Strongyloides stercoralis (Ss) infects about 30–100 million people worldwide and it is the main causative agent of strongyloidiasis, a chronic parasitic infection. Similarly, tuberculosis (TB) affects nearly 2 billion people and both Ss and TB are co-endemic as well as share a major global disease burden. Earlier studies have revealed that helminth co-infection can modify the effect produced by the host immunity against Mycobacterium tuberculosis. However, no studies have examined the association of helminth co-infection with extra-pulmonary TB, especially in tuberculous lymphadenitis (TBL). In the present study, we have addressed this gap by measuring the cytokine profile in co-infected helminth-TBL individuals. Our study first shows that TBL-Ss+ co-infection is associated with “higher bacterial burden” in the affected lymph nodes. Our study also shows that co-infection is associated with alterations in plasma cytokines, specifically Type 2, regulatory and Type 17 cytokines were elevated and pro-inflammatory cytokines were reduced. Our study demonstrates significantly diminished unstimulated or TB—antigen stimulated levels of Type 1, Type 17 or IL-1 family of cytokines in TBL-Ss+ coinfected individuals. Hence, we conclude that helminth coinfection can possibly skew the protective immunity in TBL disease or infection.

Reduced systemic and mycobacterial antigen-stimulated concentrations of IL-1β and IL-18 in tuberculous lymphadenitis

BACKGROUND

Type 1, Type 17 and other pro-inflammatory cytokines are known to play an important role in resistance to pulmonary tuberculosis. The role of these cytokines in tuberculous lymphadenitis (TBL) is not well characterized.

METHODS

To estimate the systemic and mycobacterial antigen - stimulated cytokine concentrations of Type 1, Type 17, other pro-inflammatory and regulatory cytokines in TBL, we examined both the systemic and the antigen-specific concentrations of these cytokines in TBL (n=31) before and after chemotherapy, and compared them with those with latent tuberculosis infection (LTB, n=31).

RESULTS

We observed significantly reduced systemic concentrations of the pro-inflammatory cytokines - IL-1β and IL-18 but not other Type 1 or Type 17 cytokines in TBL compared to LTB. Following standard anti-tuberculosis (TB) treatment, we observed a significant increase in the concentrations of both IL-1β and IL-18. In addition, we also observed significantly reduced baseline or mycobacterial - antigen or mitogen stimulated concentrations of IL-1β and IL-18 in TBL individuals. Similar to systemic cytokine concentrations, anti-TB treatment resulted in significantly increased concentrations of these cytokines following antigen stimulation.

CONCLUSIONS

TBL is therefore, characterized by reduced systemic and antigen-specific concentrations of IL-1β and IL-18, which are reversible following anti-TB treatment, indicating that these cytokines are potential correlates of protective immunity in TBL.

High body mass index is associated with heightened systemic and mycobacterial antigen - Specific pro-inflammatory cytokines in latent tuberculosis

High body mass index (HBMI) has been shown to be protective against active tuberculosis (TB), although the biological mechanism underlying this protection is poorly understood. The immunological association between HBMI and latent TB has never been examined. In order to study the association of HBMI with latent TB, we examined the circulating and TB- antigen or mitogen stimulated levels of a large panel of cytokines in individuals with latent TB (LTB) and high or normal body mass index (HBMI or NBMI). HBMI is characterized by heightened circulating levels of pro-inflammatory (IFNγ, TNFα, IL-22, IL-1α, IL-12 and GM-CSF) cytokines but decreased circulating levels of anti-inflammatory cytokines (IL-4, IL-5 and TGFβ). This systemic cytokine profile is associated with elevated TB-antigen and mitogen stimulated levels of IFNγ, TNFα, IL-2 and IL-1α and diminished levels of IL-10 and TGFβ. In addition, we also observed a positive correlation between the circulating levels of IFNγ, TNFα, IL-22, IL-1α with BMI and a negative correlation between the circulating levels of IL-10, TGFβ and BMI. Our data, therefore, suggest the modulation of protective and regulatory cytokines might underlie the protective effect of HBMI against the development of active TB.

Coexistent Malnutrition Is Associated with Perturbations in Systemic and Antigen-Specific Cytokine Responses in Latent Tuberculosis Infection

Malnutrition, as defined by low body mass index (BMI), is a major risk factor for the development of active tuberculosis (TB), although the biological basis underlying this susceptibility remains poorly characterized. To verify whether malnutrition affects the systemic and antigen-specific cytokine levels in individuals with latent TB (LTB), we examined circulating and TB antigen-stimulated levels of cytokines in individuals with LTB and low BMI (LBMI) and compared them with those in individuals with LTB and normal BMI (NBMI). Coexistent LBMI with LTB was characterized by diminished circulating levels of type 1 (gamma interferon [IFN-γ] and tumor necrosis factor alpha [TNF-α]), type 2 (interleukin-4 [IL-4]), type 17 (IL-22), and other proinflammatory (IL-1α, IL-1β, and IL-6) cytokines but elevated levels of other type 2 (IL-5 and IL-13) and regulatory (IL-10 and transforming growth factor beta [TGF-β]) cytokines. In addition, LBMI with LTB was associated with diminished TB antigen-induced IFN-γ, TNF-α, IL-6, IL-1α, and IL-1β levels. Finally, there was a significant positive correlation between BMI values and TNF-α and IL-1β levels and a significant negative correlation between BMI values and IL-2, IL-10, and TGF-β levels in individuals with LTB. Therefore, our data reveal that latent TB with a coexistent low BMI is characterized by diminished protective cytokine responses and heightened regulatory cytokine responses, providing a potential biological mechanism for the increased risk of developing active TB.

Coincident diabetes mellitus modulates Th1-, Th2-, and Th17-cell responses in latent tuberculosis in an IL-10- and TGF-β-dependent manner

Type 2 diabetes mellitus (DM) is a risk factor for the development of active tuberculosis (TB), although its role in the TB-induced responses in latent TB (LTB) is not well understood. Since Th1, Th2, and Th17 responses are important in immunity to LTB, we postulated that coincident DM could alter the function of these CD4(+) T-cell subsets. To this end, we examined mycobacteria-induced immune responses in the whole blood of individuals with LTB-DM and compared them with responses of individuals without DM (LTB-NDM). T-cell responses from LTB-DM are characterized by diminished frequencies of mono- and dual-functional CD4(+) Th1, Th2, and Th17 cells at baseline and following stimulation with mycobacterial antigens-purified protein derivative, early secreted antigen-6, and culture filtrate protein-10. This modulation was at least partially dependent on IL-10 and TGF-β, since neutralization of either cytokine resulted in significantly increased frequencies of Th1 and Th2 cells but not Th17 cells in LTB-DM but not LTB individuals. LTB-DM is therefore characterized by diminished frequencies of Th1, Th2, and Th17 cells, indicating that DM alters the immune response in latent TB leading to a suboptimal induction of protective CD4(+) T-cell responses, thereby providing a potential mechanism for increased susceptibility to active disease.

Modulation of pro- and anti-inflammatory cytokines in active and latent tuberculosis by coexistent Strongyloides stercoralis infection

Helminth infections are known to induce modulation of both innate and adaptive immune responses in active and latent tuberculosis (TB). However, the role of helminth infections in modulating systemic cytokine responses in active and latent tuberculosis (LTB) is not known. To define the systemic cytokine levels in helminth-TB coinfection, we measured the circulating plasma levels of Type 1, Type 2, Type 17, other pro-inflammatory and regulatory cytokines in individuals with active TB (ATB) with or without coexistent Strongyloides stercoralis (Ss) infection by multiplex ELISA. Similarly, we also measured the same cytokine levels in individuals with LTB with or without concomitant Ss infection in a cross-sectional study. Our data reveal that individuals with ATB or LTB and coexistent Ss infection have significantly lower levels of Type 1 (IFNγ, TNFα and IL-2) and Type 17 (IL-17A and IL-17F) cytokines compared to those without Ss infection. In contrast, those with ATB and LTB with Ss infection have significantly higher levels of the regulatory cytokines (IL-10 and TGFβ), and those with LTB and Ss infection also have significantly higher levels of Type 2 cytokines (IL-4, IL-5 and IL-13) as well. Finally, those with LTB (but not ATB) exhibit significantly lower levels of other pro-inflammatory cytokines (IFNα, IFNβ, IL-6, IL-12 and GM-CSF). Our data therefore reveal a profound effect of Ss infection on the systemic cytokine responses in ATB and LTB and indicate that coincident helminth infections might influence pathogenesis of TB infection and disease.

Novel targeting of PEGylated liposomes for codelivery of TGF-β1 siRNA and four antitubercular drugs to human macrophages for the treatment of mycobacterial infection: a quantitative proteomic study

Tuberculosis (TB) is still a major public health issue in developing countries, and its chemotherapy is compromised by poor drug compliance and severe side effects. This study aimed to synthesize and characterize new multimodal PEGylated liposomes encapsulated with clinically commonly used anti-TB drugs with linkage to small interfering RNA (siRNA) against transforming growth factor-β1 (TGF-β1). The novel NP-siRNA liposomes could target THP-1-derived human macrophages that were the host cells of mycobacterium infection. The biological effects of the NP-siRNA liposomes were evaluated on cell cycle distribution, apoptosis, autophagy, and the gene silencing efficiency of TGF-β1 siRNA in human macrophages. We also explored the proteomic responses to the newly synthesized NP-siRNA liposomes using the stable isotope labeling with amino acids in cell culture approach. The results showed that the multifunctional PEGylated liposomes were successfully synthesized and chemically characterized with a mean size of 265.1 nm. The novel NP-siRNA liposomes functionalized with the anti-TB drugs and TGF-β1 siRNA were endocytosed efficiently by human macrophages as visualized by transmission electron microscopy and scanning electron microscopy. Furthermore, the liposomes showed a low cytotoxicity toward human macrophages. There was no significant effect on cell cycle distribution and apoptosis in THP-1-derived macrophages after drug exposure at concentrations ranging from 2.5 to 62.5 μg/mL. Notably, there was a 6.4-fold increase in the autophagy of human macrophages when treated with the NP-siRNA liposomes at 62.5 μg/mL. In addition, the TGF-β1 and nuclear factor-κB expression levels were downregulated by the NP-siRNA liposomes in THP-1-derived macrophages. The Ingenuity Pathway Analysis data showed that there were over 40 signaling pathways involved in the proteomic responses to NP-siRNA liposome exposure in human macrophages, with 160 proteins mapped. The top five canonical signaling pathways were eukaryotic initiation factor 2 signaling, actin cytoskeleton signaling, remodeling of epithelial adherens junctions, epithelial adherens junction signaling, and Rho GDP-dissociation inhibitor signaling pathways. Collectively, the novel synthetic targeting liposomes represent a promising delivery system for anti-TB drugs to human macrophages with good selectivity and minimal cytotoxicity.

Latent tuberculosis infection--Revisiting and revising concepts

Host- and pathogen-specific factors interplay with the environment in a complex fashion to determine the outcome of infection with Mycobacterium tuberculosis (Mtb), resulting in one of three possible outcomes: cure, latency or active disease. Although much remains unknown about its pathophysiology, latent tuberculosis infection (LTBI) defined by immunologic evidence of Mtb infection is a continuum between self-cure and asymptomatic, yet active tuberculosis (TB) disease. Strain virulence, intensity of exposure to the index case, size of the bacterial inoculum, and host factors such as age and co-morbidities, each contribute to where one settles on the continuum. Currently, the diagnosis of LTBI is based on reactive tuberculin skin testing (TST) and/or a positive interferon-gamma release assay (IGRA). Neither diagnostic test reflects the activity of the infectious focus or the risk of progression to active TB. This is a critical shortcoming, as accurate and efficient detection of those with LTBI at higher risk of progression to TB disease would allow for provision of targeted preventive therapy to those most likely to benefit. Host biomarkers may prove of value in stratifying risk of development of TB. New guidelines are required for interpretation of discordance between TST and IGRA, which may be due in part to a lack of stability (that is reproducibility) of IGRA or TST results or to a delay in conversion of IGRA to positivity compared to TST. In this review, the authors elaborate on the definition, diagnosis, pathophysiology and natural history of LTBI, as well as promising methods for better stratifying risk of progression to TB. The review is centered on the human host and the clinical and epidemiologic features of LTBI that are relevant to the development of new and improved diagnostic tools.

The use of Mycobacterium tuberculosis HspX and GlcB proteins to identify latent tuberculosis in rheumatoid arthritis patients

Understanding the social conditions and immunological characteristics that allow some human immunodeficiency virus (HIV)-exposed patients to remain uninfected represents an on-going challenge. In this study, the socio-demographic and sexual behaviour characteristics and immune activation profiles of uninfected individuals exposed to HIV-infected partners were investigated. A confidential and detailed questionnaire was administered and venous blood was tested using HIV-1/enzyme immunoassays, plasma HIV-1 RNA levels/bDNA and immunophenotyping/flow cytometry to determine the frequencies of CD4 and CD8 T cells expressing activation markers. The data analysis showed significant differences (p < 0.05) for immune parameters in individuals who were uninfected, albeit exposed to HIV-infected partners, compared with unexposed individuals. In particular, the exposed, uninfected individuals had a higher frequency (median, minimum-maximum) of CD4⁺HLA-DR⁺ (4.2, 1.8-6.1), CD8⁺HLA-DR⁺ (4.6, 0.9-13.7), CD4⁺CD45RO⁺ (27.5, 14.2-46.6), CD4⁺CD45RO⁺CD62L⁺ (46.7, 33.9-67.1), CD8⁺CD45RA⁺HLA-DR⁺ (12.1, 3.4-35.8) and CD8⁺CD45RO⁺HLA-DR⁺ (9.0, 3.2-14.8) cells, a decreased percentage of CD8⁺CD28⁺ cells (11.7, 4.5-24.0) and a lower cell-surface expression of Fcγ-R/CD16 on monocytes (56.5, 22.0-130.0). The plasma HIV-1 RNA levels demonstrated detectable RNA virus loads in 57% of the HIV-1⁺ female partners. These findings demonstrate an activation profile in both CD4 and CD8 peripheral T cells from HIV-1 exposed seronegative individuals of serodiscordant couples from a referral centre in Belo Horizonte, state of Minas Gerais.

The use of Mycobacterium tuberculosis HspX and GlcB proteins to identify latent tuberculosis in rheumatoid arthritis patients

Rheumatoid arthritis (RA) is an autoimmune disease characterised by the destruction of articular cartilage and bone damage. The chronic treatment of RA patients causes a higher susceptibility to infectious diseases such as tuberculosis (TB); one-third of the world’s population is latently infected (LTBI) with Mycobacterium tuberculosis (Mtb). The tuberculin skin test is used to identify individuals LTBI, but many studies have shown that this test is not suitable for RA patients. The goal of this work was to test the specific cellular immune responses to the Mtb malate synthase (GlcB) and heat shock protein X (HspX) antigens of RA patients and to correlate those responses with LTBI status. The T-helper (Th)1, Th17 and Treg-specific immune responses to the GlcB and HspX Mtb antigens were analysed in RA patients candidates for tumour necrosis factor-α blocker treatment. Our results demonstrated that LTBI RA patients had Th1-specific immune responses to GlcB and HspX. Patients were followed up over two years and 14.3% developed active TB. After the development of active TB, RA patients had increased numbers of Th17 and Treg cells, similar to TB patients. These results demonstrate that a GlcB and HspX antigen assay can be used as a diagnostic test to identify LTBI RA patients.

Coincident pre-diabetes is associated with dysregulated cytokine responses in pulmonary tuberculosis

BACKGROUND

Cytokines play an important role in the pathogenesis of pulmonary tuberculosis (PTB)--Type 2 diabetes mellitus co-morbidity. However, the cytokine interactions that characterize PTB coincident with pre-diabetes (PDM) are not known.

METHODS

To identify the influence of coincident PDM on cytokine levels in PTB, we examined circulating levels of a panel of cytokines in the plasma of individuals with TB-PDM and compared them with those without PDM (TB-NDM).

RESULTS

TB-PDM is characterized by elevated circulating levels of Type 1 (IFNγ, TNFα and IL-2), Type 17 (IL-17A and IL-17F) and other pro-inflammatory (IL-1β, IFNβ and GM-CSF) cytokines. TB-PDM is also characterized by increased systemic levels of Type 2 (IL-5) and regulatory (IL-10 and TGFβ) cytokines. Moreover, TB antigen stimulated whole blood also showed increased levels of pro-inflammatory (IFNγ, TNFα and IL-1β) cytokines as well. However, the cytokines did not exhibit any significant correlation with HbA1C levels or with bacterial burdens.

CONCLUSION

Our data reveal that pre-diabetes in PTB individuals is characterized by heightened cytokine responsiveness, indicating that a balanced pro and anti - inflammatory cytokine milieu is a feature of pre-diabetes--TB co-morbidity.

Association between single-nucleotide polymorphism in CISH gene and susceptibility to tuberculosis in Chinese Han population

The cytokine-inducible SRC homology 2 domain (CISH) gene is up-regulated by IL-2 in response to infection, and inhibits microbial infection. The objective of the present study was to examine whether genetic variants of CISH (SNPs) are associated with increased susceptibility to tuberculosis (TB) in individuals of Chinese Han ethnicity. We sequenced five previously identified SNPs of CISH in patients with TB or healthy controls. Three of the SNPs, rs148685070 [position -639; C/C], rs414171 [position -292; A/T], and rs6768300 [position -163; C/G]) are located in the promoter region, while the fourth (rs2239751 [position +1320; A/C]) near the translation start site, and the fifth (rs622502 [position +3415; C/G]) in the third intron. The AA genotypes of the SNPs rs2239751 and rs414171 were significantly associated with TB. Multivariate logistic regression analysis demonstrated that subjects with the rs414171 AA genotype were more likely to have TB than those with the AT genotype. By contrast, we did not observe genetic variants of the rs148685070 SNP. In conclusion, two genetic variants in CISH gene appear to increase susceptibility to TB in Chinese Han population.

Importance of reciprocal balance of T cell immunity in Mycobacterium abscessus complex lung disease

Background

Little is known about the nature of the host immune response to Mycobacterium abscessus complex (MABC) infection. The aim of the present study was to investigate whether alterations in serum immunomolecule levels after treating MABC lung disease patients with antibiotics can reflect the disease-associated characteristics.

Methods

A total of 22 immunomolecules in 24 MABC lung disease patients before and after antibiotic therapy were quantitatively analyzed using a multiplex bead-based system.

Results

In general, the pre-treatment levels of T helper type 1 (Th1)-related cytokines, i.e., interferon (IFN)-γ and interleukin (IL)-12, and Th2-related cytokines, i.e., IL-4 and IL-13, were significantly decreased in patients compared with control subjects. In contrast, the pre-treatment levels of Th17-related cytokines, i.e., IL-17 and IL-23, were significantly increased in MABC patients. Interestingly, significantly higher levels of IFN-γ-induced protein (IP)-10 and monokine induced by IFN-γprotein (MIG) were detected in patients with failure of sputum conversion at post-treatment compared to patients with successful sputum conversion.

Conclusion

Reduced Th1 and Th2 responses and enhanced Th17 responses in patients may perpetuate MABC lung disease, and the immunomolecules IP-10 and MIG, induced through IFN-γ, may serve as key markers for indicating the treatment outcome.

Shortening the 'short-course' therapy- insights into host immunity may contribute to new treatment strategies for tuberculosis

Achieving global control of tuberculosis (TB) is a great challenge considering the current increase in multidrug resistance and mortality rate. Considerable efforts are therefore being made to develop new effective vaccines, more effective and rapid diagnostic tools as well as new drugs. Shortening the duration of TB treatment with revised regimens and modes of delivery of existing drugs, as well as development of new antimicrobial agents and optimization of the host response with adjuvant immunotherapy could have a profound impact on TB cure rates. Recent data show that chronic worm infection and deficiencies in micronutrients such as vitamin D and arginine are potential areas of intervention to optimize host immunity. Nutritional supplementation to enhance nitric oxide production and vitamin D-mediated effector functions as well as the treatment of worm infection to reduce immunosuppressive effects of regulatory T (Treg) lymphocytes may be more suitable and accessible strategies for highly endemic areas than adjuvant cytokine therapy. In this review, we focus mainly on immune control of human TB, and discuss how current treatment strategies, including immunotherapy and nutritional supplementation, could be optimized to enhance the host response leading to more effective treatment.

IL-10 dependent suppression of type 1, type 2 and type 17 cytokines in active pulmonary tuberculosis

Background

Although Type 1 cytokine responses are considered protective in pulmonary tuberculosis (PTB), their role as well as those of Type 2, 17 and immunoregulatory cytokines in tuberculous lymphadenitis (TBL) and latent tuberculosis (LTB) have not been well studied.

Aim and Methods

To identify cytokine responses associated with pulmonary tuberculosis (TB), TB lymphadenitits and latent TB, we examined mycobacterial antigen-specific immune responses of PTB, TBL and LTB individuals. More specifically, we examined ESAT-6 and CFP-10 induced Type 1, Type 2 and Type 17 cytokine production and their regulation using multiplex ELISA.

Results

PTB individuals exhibited a significantly lower baseline as well as antigen-specific production of Type 1 (IFNγ, TNFα and IL-2); Type 2 (IL-4) and Type 17 (IL-17A and IL-17F) cytokines in comparison to both TBL and LTB individuals. TBL individuals exhibited significantly lower antigen-specific IFNγ responses alone in comparison to LTB individuals. Although, IL-10 levels were not significantly higher, neutralization of IL-10 during antigen stimulation resulted in significantly enhanced production of IFNγ, IL-4 and IL-17A in PTB individuals, indicating that IL-10 mediates (at least partially) the suppression of cytokine responses in PTB.

Conclusion

Pulmonary TB is characterized by an IL-10 dependent antigen-specific suppression of Type 1, Type 2 and Type 17 cytokines, reflecting an important association of these cytokines in the pathogenesis of active TB.

Postexposure subunit vaccination against chronic enteric mycobacterial infection in a natural host

The control of chronic bacterial diseases with high prevalence in areas of endemicity would strongly benefit from availability of postexposure vaccines. The development of these vaccines against mycobacterial infections, such as (para)tuberculosis, is hampered by lack of experience in natural hosts. Paratuberculosis in cattle is both a mycobacterial disease of worldwide importance and a natural host model for mycobacterial infections in general. The present study showed beneficial effects of therapeutic heat shock protein 70 (Hsp70) vaccination in cattle with naturally acquired chronic infection with Mycobacterium avium subsp. paratuberculosis. Vaccination-induced protection was associated with antibody responses, rather than with induction of specific T helper 1 cells. Targeted therapeutic postexposure vaccination complementary to selective use of antibiotics could be an effective approach for control of chronic mycobacterial infections.

Role of PPE18 protein in intracellular survival and pathogenicity of Mycobacterium tuberculosis in mice

Background

Ever since its discovery the mycobacterial proline-proline-glutamic acid (PPE) family of proteins has generated a huge amount of interest. Understanding the role of these proteins in the pathogenesis of Mycobacterium tuberculosis (Mtb) is important. We have demonstrated earlier that the PPE18 protein of Mtb induces IL-10 production in macrophages with subsequent downregulation of pro-inflammatory cytokines like IL-12 and TNF-α and favors a T-helper (Th) 2-type of immune response.

Methodology/Principal Findings

Using a ppe18 genetic knock-out Mtb strain, we have now carried out infection studies in mice to understand the role of PPE18 in Mtb virulence. The studies reveal that lack of PPE18 leads to attenuation of Mtb in vivo. Mice infected with the ppe18 deleted strain have reduced infection burden in lung, liver and spleen and have better survival rates compared to mice infected with the wild-type Mtb strain.

Conclusions/Significance

Taken together our data suggest that PPE18 could be a crucial virulence factor for intracellular survival of Mtb.

Adjunct immune therapy of first-diagnosed TB, relapsed TB, treatment-failed TB, multidrug-resistant TB and TB/HIV

Aim: To evaluate the effect of an adjunct immunotherapy in randomized double-blind, placebo-controlled Phase IIb trial involving 123 TB patients. Methods: Patients were randomly allocated into two arms: one (n = 62) received a once-daily pill of V-5 Immunitor™ (V5) and the other (control; n= 61) received placebo for 30 days in addition to first- or second-line TB drugs administered under directly observed therapy. The subjects in V5 and placebo arms had first-diagnosed, relapsed, treatment-failed and multidrug-resistant TB at ratios of 17:21:11:13 and 20:19:14:8, respectively; among them, ten and seven had HIV coinfection, respectively. Results: After 1 month, 55 out of 62 patients (88.7%) became sputum smear-negative in the V5 arm (p < 0.0001), whereas in the placebo group, nine out of 61 (14.8%) had converted. The conversion rate among V5 recipients was similar, regardless of whether TB was drug-sensitive, drug-resistant or with HIV. V5 downregulated TB-associated inflammation, as shown by the normalization of elevated leukocyte counts (8.7 vs 6.3 × 10 9/l; p < 0.0001) and decreased erythrocyte sedimentation rate (22.8 vs 12.6 mm/h; p < 0.0001), whereas among placebo recipients, changes were smaller (8.9 vs 8.2 × 10 9/l and 25.1 vs 19.9 mm/h). Thirty three (54.1%) placebo patients gained on average 0.8 kg (p = 0.0002); by contrast, 57 (91.9%) out of 62 patients in the V5 group gained a mean weight of 2.9 kg (p < 0.0001). No adverse side effects or reactivation of TB were seen at any time. Conclusion: V5 is safe and effective as an immune adjunct to chemotherapy for TB and can potentially reduce the treatment duration down to 1 month.

Immunity to TB and targets for immunotherapy

For centuries the treatment of TB has presented an enormous challenge to global health. In the 20th century, the treatment of TB patients with long-term multidrug therapy gave hope that TB could be controlled and cured; however, contrary to these expectations and coinciding with the emergence of AIDS, the world has witnessed a rampant increase in hard-to-treat cases of TB, along with the emergence of highly virulent and multidrug-resistant Mycobacterium tuberculosis strains. Unfortunately, these bacteria are now circulating around the world, and there are few effective drugs to treat them. As a result, the prospects for improved treatment and control of TB in the 21st century have worsened and we urgently need to identify new therapies that deal with this problem. The potential use of immunotherapy for TB is now of greater consideration than ever before, as immunotherapy could potentially overcome the problem of drug resistance. TB immunotherapy targets the already existing host anti-TB immune response and aims to enhance killing of the bacilli. For this purpose, several approaches have been used: the use of anti-Mycobacteria antibodies; enhancing the Th1 protective responses by using mycobacterial antigens or increasing Th1 cytokines; interfering with the inflammatory process and targeting of immunosuppressive pathways and targeting the cell activation/proliferation pathways. This article reviews our current understanding of TB immunity and targets for immunotherapy that could be used in combination with current TB chemotherapy.

Distinguishing Latent from Active Mycobacterium tuberculosis Infection Using Elispot Assays: Looking Beyond Interferon-gamma

Mycobacterium tuberculosis (MTB) is a global heath epidemic, its threat amplified by HIV infection and the emergence of multidrug-resistant tuberculosis (MDR-TB). Interferon (IFN)-gamma release assays (IGRAs) have improved the accuracy of detection of MTB exposure in some subject groups as compared to the Tuberculin Skin Test (TST). However, as IFN-gamma is produced by both fully rested and more recently activated populations of memory T cells, it is not surprising that the measurement of this cytokine alone cannot accurately distinguish Latent TB Infected (LTBI) subjects from those with active (infectious) disease. Accurate and rapid diagnosis of infectious individuals would allow medication to be properly allocated and other actions taken to more effectively curtail MTB spread. Analysis of multi-cytokine profiles ex vivo after stimulation of PBMCs from LTBI and active MTB subjects indicate the real possibility of successfully discerning these two disease states within 24 hours of a subject’s blood draw. Due to the unparalleled sensitivity, low cost, and ease of use of Elispot assays, we propose that via a multiplex Elispot platform the accurate distinction of LTBI from active MTB-infected individuals is within reach.

New biomarkers with relevance to leprosy diagnosis applicable in areas hyperendemic for leprosy

Leprosy is not eradicable with currently available diagnostics or interventions, as evidenced by its stable incidence. Early diagnosis of Mycobacterium leprae infection should therefore be emphasized in leprosy research. It remains challenging to develop tests based on immunological biomarkers that distinguish individuals controlling bacterial replication from those developing disease. To identify biomarkers for field-applicable diagnostics, we determined cytokines/chemokines induced by M. leprae proteins in blood of leprosy patients and endemic controls (EC) from high leprosy-prevalence areas (Bangladesh, Brazil, Ethiopia) and from South Korea, where leprosy is not endemic anymore. M. leprae-sonicate-induced IFN-γ was similar for all groups, excluding M. leprae/IFN-γ as a diagnostic readout. By contrast, ML2478 and ML0840 induced high IFN-γ concentrations in Bangladeshi EC, which were completely absent for South Korean controls. Importantly, ML2478/IFN-γ could indicate distinct degrees of M. leprae exposure, and thereby the risk of infection and transmission, in different parts of Brazilian and Ethiopian cities. Notwithstanding these discriminatory responses, M. leprae proteins did not distinguish patients from EC in one leprosy-endemic area based on IFN-γ. Analyses of additional cytokines/chemokines showed that M. leprae and ML2478 induced significantly higher concentrations of MCP-1, MIP-1β, and IL-1β in patients compared with EC, whereas IFN-inducible protein-10, like IFN-γ, differed between EC from areas with dissimilar leprosy prevalence. This study identifies M. leprae-unique Ags, particularly ML2478, as biomarker tools to measure M. leprae exposure using IFN-γ or IFN-inducible protein-10, and also shows that MCP-1, MIP-1β, and IL-1β can potentially distinguish pathogenic immune responses from those induced during asymptomatic exposure to M. leprae.

CD4 lymphocyte dynamics in Tanzanian pulmonary tuberculosis patients with and without HIV co-infection

Background

The interaction of HIV and tuberculosis (TB) on CD4 levels over time is complex and has been divergently reported.

Methods

CD4 counts were assessed from time of diagnosis till the end of TB treatment in a cohort of pulmonary TB patients with and without HIV co-infection and compared with cross-sectional data on age- and sex-matched non-TB controls from the same area.

Results

Of 1,605 study participants, 1,250 were PTB patients and 355 were non-TB controls. At baseline, HIV was associated with 246 (95% CI: 203; 279) cells per μL lower CD4 counts. All PTB patients had 100 cells per μL lower CD4 counts than the healthy controls. The CD4 levels were largely unchanged during a five-month of TB treatment. HIV infected patients not receiving ART at any time and those already on ART at baseline had no increase in CD4 counts after 5 months of TB treatment, whereas those prescribed ART between baseline and 2 months, and between 2 and 5 months increased by 69 (22;117) and 110 (52; 168) CD4 cells per μL after 5 months.

Conclusions

The increase in circulating CD4 levels observed in PTB in patients is acquired after 2 months of treatment irrespective of HIV status. Initiation of ART is the strongest factor correlated with CD4 increase during TB treatment.

Trial registration number

Clinical trials.gov: NCT00311298

Lactoferrin Augmentation of the BCG Vaccine Leads to Increased Pulmonary Integrity

The goal of vaccination to prevent tuberculosis disease (TB) is to offer long-term protection to the individual and the community. In addition, the success of any protective TB vaccine should include the ability to limit cavitary formation and disease progression. The current BCG vaccine protects against disseminated TB disease in children by promoting development of antigenic-specific responses. However, its efficacy is limited in preventing postprimary pulmonary disease in adults that is responsible for the majority of disease and transmission. This paper illustrates the use of lactoferrin as an adjuvant to boost efficacy of the BCG vaccine to control organism growth and limit severe manifestation of pulmonary disease. This resulting limitation in pathology may ultimately, limit spread of bacilli and subsequent transmission of organisms between individuals. The current literature is reviewed, and data is presented to support molecular mechanisms underlying lactoferrin's utility as an adjuvant for the BCG vaccine.

Interleukin-10 gene promoter polymorphisms and their protein production in pleural fluid in patients with tuberculosis

Associations of interleukin-10 (IL-10) gene promoter polymorphisms and pleural tuberculosis risk remain unclear. The objective of this study was to determine IL-10 gene promoter polymorphisms at -1082, -819 and -592 sites and their protein production in pleural fluid (PF) in patients with and without pleural tuberculosis. IL-10 gene promoter polymorphisms at the -1082, -819 and -592 sites were genotyped using a SNaPshot assay. Protein levels of IL-10 in PF were measured using an enzyme-linked immunosorbent assay. There were no significant differences in the genotype and allele frequencies of IL-10 gene promoter polymorphisms at position -1082 between the pleural tuberculosis and the control groups. However, the frequency of -819 T or -592 A alleles was significantly more common in patients with pleural tuberculosis than controls. The protein levels of IL-10 in PF were statistically higher in the pleural tuberculosis group than in the control group. Moreover, the polymorphisms at the -1082, -819 and -592 sites were associated with protein levels of IL-10 in PF in the pleural tuberculosis group, while in the control group, only the polymorphism at position -1082 correlated with the protein levels. These findings support the association between IL-10 promoter polymorphisms at -819 and -592 sites and their protein production with pleural tuberculosis risk.

Malaria prevention reduces in-hospital mortality among severely ill tuberculosis patients: a three-step intervention in Bissau, Guinea-Bissau

Background

Malaria and Tuberculosis (TB) are important causes of morbidity and mortality in Africa. Malaria prevention reduces mortality among HIV patients, pregnant women and children, but its role in TB patients is not clear. In the TB National Reference Center in Guinea-Bissau, admitted patients are in severe clinical conditions and mortality during the rainy season is high. We performed a three-step malaria prevention program to reduce mortality in TB patients during the rainy season.

Methods

Since 2005 Permethrin treated bed nets were given to every patient. Since 2006 environmental prevention with permethrin derivates was performed both indoor and outdoor during the rainy season. In 2007 cotrimoxazole prophylaxis was added during the rainy season. Care was without charge; health education on malaria prevention was performed weekly. Primary outcomes were death, discharge, drop-out.

Results

427, 346, 549 patients were admitted in 2005, 2006, 2007, respectively. Mortality dropped from 26.46% in 2005 to 18.76% in 2007 (p-value 0.003), due to the significant reduction in rainy season mortality (death/discharge ratio: 0.79, 0.55 and 0.26 in 2005, 2006 and 2007 respectively; p-value 0.001) while dry season mortality remained constant (0.39, 0.37 and 0.32; p-value 0.647). Costs of malaria prevention were limited: 2€/person. No drop-outs were observed. Health education attendance was 96-99%.

Conclusions

Malaria prevention in African tertiary care hospitals seems feasible with limited costs. Vector control, personal protection and cotrimoxazole prophylaxis seem to reduce mortality in severely ill TB patients. Prospective randomized trials are needed to confirm our findings in similar settings.

Trial registration number

Current Controlled Trials: ISRCTN83944306

Adjunct oral immunotherapy in patients with re-treated, multidrug-resistant or HIV-coinfected TB

This Phase IIb, placebo-controlled study involved 55 TB patients treated with anti-TB therapy. They were divided into two groups, matched by age, gender, baseline bodyweight and clinical manifestations: one group (n = 27) received a once-daily V-5 Immunitor (V5) immunotherapy pill and the other (n = 28) received placebo. Only one (3.7%) and three (10.7%) subjects in V5 and placebo arms, respectively had first-diagnosed, drug-sensitive TB; the remaining patients had re-treated TB, multidrug-resistant TB or HIV-TB coinfection. After 1 month, 26 out of 27 patients (96.3%) became sputum smear negative in the V5 group (p < 0.0000001), whereas seven out of 28 (25%) in the placebo group had converted (p = 0.005). V5 contributed to the downregulation of TB-associated inflammation, as shown by normalization of high leukocyte counts, erythrocyte sedimentation rate and faster defervescence than controls. Patients in both arms experienced an increase in the levels of hemoglobin corresponding to 128.9 ± 17.6 versus 133.1 ± 14.7 g/l (p = 0.03) and 112.6 ± 14 versus 117 ± 11.7 g/l (p = 0.03) in V5 and placebo arms, respectively. In total, 19 out of 28 placebo patients (67.9%) gained, on average, 1.07 kg (59.1 ± 10 vs 60.1 ± 10.4 kg; p = 0.003). By contrast, all patients in the V5 group gained weight with mean 3.4 kg (59.7 ± 8 vs 63.1 ± 9 kg; p = 5.7E-007). Clinical symptoms improved among all patients in V5 arm, while 28.6% of patients on placebo reported satisfactory results (p = 0.007). No adverse or side effects attributable to V5 were seen at any time. Further studies are needed to gauge the extent of the benefits of V5 as safe and effective adjunct immunotherapy for TB.