Why does tuberculosis lead to specific inflammation?

Association between latent tuberculosis and ischemic heart disease: a hospital-based cross-sectional study from Saudi Arabia

Introduction

atherosclerosis could be a sequela of long-term activation of cell-mediated immunity as the case of latent tuberculosis infection. Atherosclerosis is the main pathological event in ischemic heart disease. The present study aimed to assess the prevalence of Latent tuberculosis infection (LTBI) among patients with ischemic heart disease (IHD) and to detect the association between both diseases.

Methods

this cross-sectional study included 98 patients with a history of previously diagnosed ischemic heart disease who did a multi-detector computed tomography coronary angiogram (MDCTCA). Detailed clinical examination and investigations as chest X-ray and sputum examination were done for those with positive QuantiFERON-TB Gold test (QFT) to exclude active tuberculosis (TB). Participants having positive QFT results but with no evidence of active TB were considered as LTBI positive.

Results

the prevalence of LTBI in patients with IHD was 19.3% as only nineteen of the ninety-eight patients were diagnosed with latent tuberculosis infection using the QuantiFERON serum test. Eighty-four percent (84.2%) of patients with LTBI had coronary artery atherosclerosis (CAA) compared to only 55.6% in patients without LTBI with a statistically significant difference. In multivariable analysis, Diabetes Mellitus (DM) (AOR 0.179, 95% C.I.: 0.03-0.967), and LTBI (AOR 1.024, 95% C.I.: 1.002-1.736) were significantly associated with coronary artery atherosclerosis (p=0.0001, and p= 0.003 respectively).

Conclusion

the prevalence of latent tuberculosis infection among patients with ischemic heart diseases is high. Among different factors that are already well known to precipitate ischemic heart disease, latent tuberculosis should be considered.

Adjunctive Phosphodiesterase-4 Inhibitor Therapy Improves Antibiotic Response to Pulmonary Tuberculosis in a Rabbit Model

Objectives

Adjunctive host-directed therapy is emerging as a new potential approach to improve the outcome of conventional antimicrobial treatment for tuberculosis (TB). We tested the ability of a phosphodiesterase-4 inhibitor (PDE4i) CC-11050, co-administered with the first-line anti-TB drug isoniazid (INH), to accelerate bacillary killing and reduce chronic inflammation in the lungs of rabbits with experimental Mycobacterium tuberculosis (Mtb) infection.

Methods

A rabbit model of pulmonary TB that recapitulates the pathologic manifestations seen in humans was used. Rabbits were infected with virulent Mtb by aerosol exposure and treated for eight weeks with INH with or without CC-11050, starting at four weeks post infection. The effect of CC-11050 treatment on disease severity, pathology, bacillary load, T cell proliferation and global lung transcriptome profiles were analyzed.

Results

Significant improvement in bacillary clearance and reduced lung pathology and fibrosis were noted in the rabbits treated for eight weeks with INH + CC-11050, compared to those treated with INH or CC-11050 only. In addition, expression of host genes associated with tissue remodeling, tumor necrosis factor alpha (TNF-α) regulation, macrophage activation and lung inflammation networks was dampened in CC-11050-treated, compared to the untreated rabbits.

Conclusions

Adjunctive CC-11050 therapy significantly improves the response of rabbits with experimental pulmonary TB to INH treatment. We propose that CC-11050 may be a promising candidate for host directed therapy of patients with pulmonary TB, reducing the duration and improving clinical outcome of antibiotic treatment.

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CC-11050 is an anti-inflammatory molecule targeting host phosphodiesterase-4.

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CC-11050 plus isoniazid therapy significantly reduced bacillary load and pathology in a rabbit model pulmonary tuberculosis.

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CC-11050 can be a promising candidate for adjunctive host directed therapy of patients with active pulmonary tuberculosis.

In 2013, tuberculosis (TB) caused by Mycobacterium tuberculosis (Mtb) killed 1.5 million people worldwide. Current antibiotic therapy for tuberculosis is ineffective in eliminating the infecting bacilli and/or disease pathology such as lung fibrosis. Therefore, alternate approaches are urgently needed to control the TB epidemic. In this study, using a rabbit model of pulmonary TB, which closely mimics the human disease, we tested the hypothesis that reducing the host inflammatory response during Mtb infection would improve the outcome of antibiotic treatment; we show that adjunctive phosphodiesterase-4 inhibition therapy with isoniazid improves bacterial clearance and lung pathology.

CC chemokine receptor 4 contributes to innate NK and chronic stage T helper cell recall responses during Mycobacterium bovis infection

Cysteine-cysteinyl chemokine receptor 4 (CCR4) is expressed by a variety of T-cell subsets and leukocytes. This study examined the participation of CCR4 in response to pulmonary infection with Mycobacterium bovis Bacille-Calmette-Guerin (BCG). Constitutive and induced CCR4 agonist expression was detected among large mononuclear cells. The course of infection and mobilization of effector cell populations were then analyzed in CCR4 knockout (CCR4(-/-)) mice. Compared with controls, CCR4(-/-) mice displayed delayed innate stage (<2 weeks) bacterial clearance and reduced late stage inflammation. Innate impairment was associated with reduced natural killer cell activation. In the adaptive phase, CCR4(-/-) mice generated effector T cells in draining lymph nodes and accumulated effector T cells in lungs, which resulted in normal adaptive stage bacterial elimination at 2 to 4 weeks. However, during the late stage, CCR4(-/-) mice had reduced interferonγ+CD4(+)α/β+ (Th1) and interleukin (IL)-17+CD4(+)α/β+ (Th17) T helper cells in lungs. In contrast, IL-17+ γ/δ T cells in lungs were unaffected. When challenged with mycobacterial antigen- (Ag-) Ag-coated beads to elicit a recall granulomatous response, CCR4(-/-) mice displayed abrogated recall granuloma formation and reduced interferon γ+ Th1 cells. These findings indicate that CCR4 supports innate natural killer cell activation and sustains later CD4(+) Th effector/memory antimycobacterial responses in the lung but is redundant in the early adaptive elimination phase.

Cysteine-cysteinyl chemokine receptor 6 mediates invariant natural killer T cell airway recruitment and innate stage resistance during mycobacterial infection

This study examined the contribution of cysteine-cysteinyl chemokine receptor 6 (CCR6) to the innate pulmonary antimycobacterial immune response. Using a mouse model of Mycobacterium bovis BCG airway infection, we detected maximal induction of the CCR6 agonist CCL20 in lungs at 1 week after infection. Infected CCR6 knockout (CCR6-/-) mice displayed an early impairment of bacterial clearance, but ultimately eliminated the attenuated organisms with the onset of adaptive immunity. Flow-cytometric analyses of bronchoalveolar lavages and dispersed lungs revealed a 60% reduction in TCR-α/β+ T cells in airways but no compromise of TCR-γ/δ+ T cells. The subset of CD1d-restricted, CD8-TCR-α/β+ natural killer cells, which mediate innate mycobacterial resistance, was profoundly reduced (90%). Analysis of the adaptive response using ovalbumin-specific transgenic TCR T cell (OT-II) transfer combined with infection with recombinant M. bovis BCG producing ovalbumin peptide indicated no impairment of adaptive T cell activation in CCR6-/- mice. There was also no impairment of the induction of cytokine-producing cells in draining lymphoid tissue of CCR6-/- mice. Taken together, our findings indicate that CCR6 is not required for induction of the adaptive antimycobacterial response, but is likely critical to airway compartment mobilization of TCR-α/β+CCR6+ innate and adaptive effector T cells.