Effect of HMG-CoA reductase inhibitors on activation of human gammadeltaT cells induced by Mycobacterium tuberculosis antigens

Analysis of the components of Mycobacterium tuberculosis heat-resistant antigen (Mtb-HAg) and its regulation of γδ T-cell function

BACKGROUND

Mycobacterium tuberculosis heat-resistant antigen (Mtb-HAg) is a peptide antigen released from the mycobacterial cytoplasm into the supernatant of Mycobacterium tuberculosis (Mtb) attenuated H37Ra strain after autoclaving at 121 °C for 20 min. Mtb-HAg can specifically induce γδ T-cell proliferation in vitro. However, the exact composition of Mtb-HAg and the protein antigens that are responsible for its function are currently unknown.

METHODS

Mtb-HAg extracted from the Mtb H37Ra strain was subjected to LC‒MS mass spectrometry. Twelve of the identified protein fractions were recombinantly expressed in Escherichia coli by genetic engineering technology using pET-28a as a plasmid and purified by Ni-NTA agarose resin to stimulate peripheral blood mononuclear cells (PBMCs) from different healthy individuals. The proliferation of γδ T cells and major γδ T-cell subset types as well as the production of TNF-α and IFN-γ were determined by flow cytometry. Their proliferating γδ T cells were isolated and purified using MACS separation columns, and Mtb H37Ra-infected THP-1 was co-cultured with isolated and purified γδ T cells to quantify Mycobacterium viability by counting CFUs.

RESULTS

In this study, Mtb-HAg from the attenuated Mtb H37Ra strain was analysed by LC‒MS mass spectrometry, and a total of 564 proteins were identified. Analysis of the identified protein fractions revealed that the major protein components included heat shock proteins and Mtb-specific antigenic proteins. Recombinant expression of 10 of these proteins in by Escherichia coli genetic engineering technology was used to successfully stimulate PBMCs from different healthy individuals, but 2 of the proteins, EsxJ and EsxA, were not expressed. Flow cytometry results showed that, compared with the IL-2 control, HspX, GroEL1, and GroES specifically induced γδ T-cell expansion, with Vγ2δ2 T cells as the main subset, and the secretion of the antimicrobial cytokines TNF-α and IFN-γ. In contrast, HtpG, DnaK, GroEL2, HbhA, Mpt63, EsxB, and EsxN were unable to promote γδ T-cell proliferation and the secretion of TNF-α and IFN-γ. None of the above recombinant proteins were able to induce the secretion of TNF-α and IFN-γ by αβ T cells. In addition, TNF-α, IFN-γ-producing γδ T cells inhibit the growth of intracellular Mtb.

CONCLUSION

Activated γδ T cells induced by Mtb-HAg components HspX, GroES, GroEL1 to produce TNF-α, IFN-γ modulate macrophages to inhibit intracellular Mtb growth. These data lay the foundation for subsequent studies on the mechanism by which Mtb-HAg induces γδ T-cell proliferation in vitro, as well as the development of preventive and therapeutic vaccines and rapid diagnostic reagents.

Association between biomarkers of inflammation and dyslipidemia in drug resistant tuberculosis in Uganda

BACKGROUND

Active tuberculosis (TB) significantly increases the risk of cardiovascular disease, but the underlying mechanisms remain unclear. This study aimed to investigate the association between inflammation biomarkers and dyslipidemia in patients with drug-resistant TB (DR-TB).

METHODS

This was a secondary analysis of data from a cross-sectional multi-center study in Uganda conducted 2021. Participants underwent anthropometric measurements and laboratory tests included a lipid profile, full haemogram and serology for HIV infection. Dyslipidemia was defined as total cholesterol > 5.0 mmol/l and/or low-density lipoprotein cholesterol > 4.14 mmol/l, and/or triglycerides (TG) ≥ 1.7 mmol/l, and/or high density lipoprotein cholesterol (HDL-c) < 1.03 mmol/l for men and < 1.29 mmol/l for women. Biomarkers of inflammation were leukocyte, neutrophil, lymphocyte, monocyte, and platelet counts, as well as neutrophil/lymphocyte (NLR), platelet/lymphocyte, and lymphocyte/monocyte (LMR) ratios, mean corpuscular volume (MCV), and the systemic immune inflammation index (SII) (neutrophil × platelet/lymphocyte). Modified Poisson Regression analysis was used for determining the association of the biomarkers and dyslipidemia.

RESULTS

Of 171 participants, 118 (69.0%) were co-infected with HIV. The prevalence of dyslipidemia was 70.2% (120/171) with low HDL-c (40.4%, 69/171) and hypertriglyceridemia (22.5%, 38/169) being the most common components. Patients with dyslipidemia had significantly higher lymphocyte (P = 0.008), monocyte (P < 0.001), and platelet counts (P = 0.014) in addition to a lower MCV (P < 0.001) than those without dyslipidemia. Further, patients with dyslipidemia had lower leucocyte (P < 0.001) and neutrophil (P = 0.001) counts, NLR (P = 0.008), LMR (P = 0.006), and SII (P = 0.049). The MCV was inversely associated with low HDL-C (adjusted prevalence ratio (aPR) = 0.97, 95% CI 0.94-0.99, P = 0.023) but was positively associated with hypertriglyceridemia (aPR = 1.04, 95% CI 1.00-1.08, P = 0.052).

CONCLUSIONS

Individuals with dyslipidemia exhibited elevated lymphocyte, monocyte, and platelet counts compared to those without. However, only MCV demonstrated an independent association with specific components of dyslipidemia. There is need for further scientific inquiry into the potential impact of dyslipidemia on red cell morphology and a pro-thrombotic state among patients with TB.

Association between statin use and tuberculosis risk in patients with bronchiectasis: a retrospective population-based cohort study in Taiwan

BACKGROUND

Chronic airway diseases have been associated with an increased risk of tuberculosis (TB); however, data in patients with bronchiectasis is limited. Statins have been shown to exhibit anti-inflammatory effects by modulating the inflammatory response. This study investigated whether statin treatment could reduce the risk of TB in patients with bronchiectasis.

METHODS

We conducted a retrospective cohort study using a nationwide population database of patients with bronchiectasis who did or did not receive statin treatment. The defined daily dose (DDD) of statin, current or past statin user and statin exposure time were measured for the impact of statin use. The primary outcome was the incidence of new-onset TB. Considering of potential immortal time bias due to stain exposure time, Cox regression models with time-dependent covariates were employed to estimate HRs with 95% CIs for TB incidence among patients with bronchiectasis.

RESULTS

Patients with bronchiectasis receiving statin treatment had a decreased risk of TB. After adjusting for age, sex, income, comorbidities and Charlson Comorbidity Index, statin users had a 0.59-fold lower risk of TB incidence compared with non-statin users (95% CI 0.40 to 0.88; p=0.0087). Additionally, compared with non-statin users, statin treatment was a protective factor against TB in users with a cumulative DDD greater than 180 per year, with an HR of 0.32 (95% CI 0.12 to 0.87; p=0.0255).

CONCLUSIONS

Statin treatment demonstrated a dose-dependent protective effect and was associated with a reduced risk of TB in patients with bronchiectasis. These findings suggest that statins may play a role in lowering TB risk by modulating airway inflammation in this patient population.

Atorvastatin Potentially Reduces Mycobacterial Severity through Its Action on Lipoarabinomannan and Drug Permeability in Granulomas

The majority of preclinical research has shown that Mycobacterium tuberculosis can modify host lipids in various ways. To boost its intramacrophage survival, M. tuberculosis causes host lipids to build up, resulting in the development of lipid-laden foam cells. M. tuberculosis binds to and enters the macrophage via the cell membrane cholesterol. Aggregation of cholesterol in the cell wall of M. tuberculosis and an increase in vascularity at the granuloma site reduce the permeability of rifampicin and isoniazid concentrations. However, very few studies have assessed the effect of statins on drug penetration. Here, we used atorvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, to observe its effect on the bacterial burden by increasing the drug concentration at the infection site. We looked into how atorvastatin could be used in conjunction with first-line drugs to promote drug permeation. In this study, we detected an accumulation of drugs at the peripheral sites of the lungs and impaired drug distribution to the diseased sites. The efficacy of antituberculosis drugs, with atorvastatin as an adjunct, on the viability of M. tuberculosis cells was demonstrated. A nontoxic statin dosage established phenotypic and normal granuloma vasculature and showed an additive effect with rifampicin and isoniazid. Our data show that statins help to reduce the tuberculosis bacterial burden. Our findings reveal that the bacterial load is connected with impaired drug permeability resulting from lipid accumulation in the bacterial cell wall. Statin therapy combined with antituberculosis medications have the potential to improve treatment in tuberculosis patients. IMPORTANCE Mycobacterium tuberculosis binds to and enters the macrophage via the cell membrane cholesterol. M. tuberculosis limits phagosomal maturation and activation without engaging in phagocytosis. Aggregation of cholesterol in the cell wall of M. tuberculosis and an increase in the vascularity at the granuloma site reduce the permeability of rifampicin and isoniazid concentrations. However, very few studies have assessed the effect of statins on drug penetration, which can be increased through a reduction in cholesterol and vascularity. Herein, we used atorvastatin, a 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, to observe its effect on bacterial burden through increasing the drug concentration at the infection site. Our main research goal is to diminish mycobacterial dissemination and attenuate bacterial growth by increasing drug permeability.

Statin Use May Be Associated With Reduced Active Tuberculosis Infection: A Meta-Analysis of Observational Studies

Background: Tuberculosis remains one of the leading causes of mortality among the infectious diseases, while statins were suggested to confer anti-infective efficacy in experimental studies. We aimed to evaluate the association between statin use and tuberculosis infection in a meta-analysis.

Method: Relevant studies were obtained via systematically search of PubMed and Embase databases. A random or a fixed effect model was applied to pool the results according to the heterogeneity among the included studies. Subgroup analyses according to the gender and diabetic status of the participants were performed. We assessed the quality of evidence with the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

Results: Nine observational studies were included. Significant heterogeneity was detected among the studies (p for Cochrane's Q test <0.001, I² = 93%). The GRADE approach showed generally low quality of evidence. Pooled results showed that statin use was associated with reduced active tuberculosis infection (risk ratio [RR]: 0.60, 95% confidence interval [CI]: 0.45 to 0.75, p < 0.001). Subgroup analyses showed that the negative association between statin use and active tuberculosis infection was consistent in men (RR: 0.63, p = 0.01) and women (RR: 0.58, p < 0.001), in participants with (RR: 0.63, p = 0.02) and without diabetes (RR: 0.50, p < 0.001), in retrospective cohort studies (RR: 0.56, p = 0.02), prospective cohort studies (RR: 0.76, p = 0.03), nested case-controls studies (RR: 0.57, p < 0.001), and case-control studies (RR: 0.60, p < 0.001), and in studies with statin used defined as any use within 1 year (RR: 0.59, p < 0.001) or during follow-up (RR: 0.61, p < 0.001). Significant publication bias was detected (p for Egger's regression test = 0.046). Subsequent “trim and fill” analyses retrieved an unpublished study to generate symmetrical funnel plots, and meta-analysis incorporating this study did not significantly affect the results (RR: 0.72, 95% CI: 0.68 to 0.76, p < 0.001).

Conclusions: Statin use may be associated with reduced active tuberculosis infection. Randomized controlled trials (RCTs) are needed to confirm the potential preventative role of statin use on tuberculosis infection.

Anti-tuberculous Effects of Statin Therapy: A Review of Literature

Tuberculosis (TB) is a chronic infection caused by Mycobacterium tuberculosis (M. TB). It is transmitted through respiratory droplets. Increased cholesterol level is a predisposing factor for TB. M. TB uses cholesterol in the host macrophage membranes to bind and enter the macrophages. Statins are the drugs that are prescribed to hyperlipidemic patients to maintain their lipid levels in the normal range, thereby reducing the risk of stroke and cardiovascular events. Moreover, statins aid in reducing the levels of cholesterol in human macrophages. Therefore, a reduction in the membrane cholesterol minimizes the entry of TB pathogen inside macrophages. Furthermore, acting as vitamin D3 analogs and positively influencing pancreatic beta-cell function in a chronic diabetic state, statins minimize the occurrence of M. TB infection among diabetic population as well. This review aims to provide a comprehensive detail of all in vitro, in vivo, and retrospective studies that investigated the effects of statins in relation to the prevention or treatment of TB infection.

Human Peripheral Blood Gamma Delta T Cells: Report on a Series of Healthy Caucasian Portuguese Adults and Comprehensive Review of the Literature

Gamma delta T cells (Tc) are divided according to the type of Vδ and Vγ chains they express, with two major γδ Tc subsets being recognized in humans: Vδ2Vγ9 and Vδ1. Despite many studies in pathological conditions, only a few have quantified the γδ Tc subsets in healthy adults, and a comprehensive review of the factors influencing its representation in the blood is missing. Here we quantified the total γδ Tc and the Vδ2/Vγ9 and Vδ1 Tc subsets in the blood from 30 healthy, Caucasian, Portuguese adults, we characterized their immunophenotype by 8-color flow cytometry, focusing in a few relevant Tc markers (CD3/TCR-γδ, CD5, CD8), and costimulatory (CD28), cytotoxic (CD16) and adhesion (CD56) molecules, and we examined the impacts of age and gender. Additionally, we reviewed the literature on the influences of race/ethnicity, age, gender, special periods of life, past infections, diet, medications and concomitant diseases on γδ Tc and their subsets. Given the multitude of factors influencing the γδ Tc repertoire and immunophenotype and the high variation observed, caution should be taken in interpreting “abnormal” γδ Tc values and repertoire deviations, and the clinical significance of small populations of “phenotypically abnormal” γδ Tc in the blood.

Statins: a viable candidate for host-directed therapy against infectious diseases

Statins were first identified over 40 years ago as lipid-lowering drugs and have been remarkably effective in treating cardiovascular diseases. As research advanced, the protective effects of statins were additionally attributed to their anti-inflammatory, antioxidative, anti-thrombotic and immunomodulatory functions rather than lipid-lowering abilities alone. By promoting host defence mechanisms and inhibiting pathological inflammation, statins increase survival in human infectious diseases. At the cellular level, statins inhibit the intermediates of the host mevalonate pathway, thus compromising the immune evasion strategies of pathogens and their survival. Here, we discuss the potential use of statins as an inexpensive and practical alternative or adjunctive host-directed therapy for infectious diseases caused by intracellular pathogens, such as viruses, protozoa, fungi and bacteria.

Potential Effect of Statins on Mycobacterium tuberculosis Infection

Tuberculosis is one of the 10 leading causes of death in the world. The current treatment is based on a combination of antimicrobials administered for six months. It is essential to find therapeutic agents with which the treatment time can be shortened and strengthen the host immune response against Mycobacterium tuberculosis. M. tuberculosis needs cholesterol to infect and survive inside the host, but the progression of the infection depends to a large extent on the capacity of the immune response to contain the infection. Statins inhibit the synthesis of cholesterol and have pleiotropic effects on the immune system, which have been associated with better results in the treatment of several infectious diseases. Recently, it has been reported that cells treated with statins are more resistant to M. tuberculosis infection, and they have even been proposed as adjuvants in the treatment of M. tuberculosis infection. The aim of this review is to summarize the immunopathogenesis of tuberculosis and its mechanisms of evasion and to compile the available scientific information on the effect of statins in the treatment of tuberculosis.

Statins increase rifampin mycobactericidal effect

Mycobacterium leprae and Mycobacterium tuberculosis antimicrobial resistance has been followed with great concern during the last years, while the need for new drugs able to control leprosy and tuberculosis, mainly due to extensively drug-resistant tuberculosis (XDR-TB), is pressing. Our group recently showed that M. leprae is able to induce lipid body biogenesis and cholesterol accumulation in macrophages and Schwann cells, facilitating its viability and replication. Considering these previous results, we investigated the efficacies of two statins on the intracellular viability of mycobacteria within the macrophage, as well as the effect of atorvastatin on M. leprae infections in BALB/c mice. We observed that intracellular mycobacteria viability decreased markedly after incubation with both statins, but atorvastatin showed the best inhibitory effect when combined with rifampin. Using Shepard's model, we observed with atorvastatin an efficacy in controlling M. leprae and inflammatory infiltrate in the BALB/c footpad, in a serum cholesterol level-dependent way. We conclude that statins contribute to macrophage-bactericidal activity against Mycobacterium bovis, M. leprae, and M. tuberculosis. It is likely that the association of statins with the actual multidrug therapy effectively reduces mycobacterial viability and tissue lesion in leprosy and tuberculosis patients, although epidemiological studies are still needed for confirmation.

Mycobacteria and biological response modifiers: two sides of the relationship

With increasing use of biological response modifiers (BRMs) for various systemic inflammatory diseases there is a need to be vigilant about complications with the use of these therapies. It is important to have appropriate screening for the infections in patients requiring BRMs. However, many studies have reported benefits of certain BRMs in the treatment of infections such as tuberculosis as adjuncts. Continued research and technical advances in immunogenetics helps understand complex mechanisms in the usage of the BRMs. This article summarizes the different aspects of the relationship between mycobacterial infections and the use of various BRMs for inflammatory conditions.

Coexisting aggregates in mixed aerosol OT and cholesterol microemulsions

Dynamic light scattering and NMR spectroscopic experimental evidence suggest the coexistence of two compositionally different self-assembled particles in solution. The self-assembled particles form in solutions containing water, Aerosol OT (AOT, sodium bis(2-ethylhexyl) sulfosuccinate) surfactant, and cholesterol in cyclohexane. In a similar series of studies carried out in 1-octanol only one aggregate type, that is, reverse micelles, is observed. Dynamic light scattering measurements reveal the presence of two different types of aggregates in the microemulsions formed in cyclohexane, demonstrating the coexistence of two compositionally distinct structures with very similar Gibbs energies. One particle type consists of standard AOT reverse micelles while the second type of particle consists of submicellar aggregates including cholesterol as well as small amounts of AOT and water. In microemulsions employing 1-octanol as the continuous medium, AOT reverse micelles form in a dispersed solution of cholesterol in 1-octanol. Although the size distribution of self-assembled particles is well-known for many different systems, evidence for simultaneous formation of two distinctly sized particles in solution that are chemically different is unprecedented. The ability to form microemulsion solutions that contain coexisting particles may have important applications in drug formulation and administration, particularly as applied to drug delivery using cholesterol as a targeting agent.