Angiogenic activity of sera from pulmonary tuberculosis patients in relation to IL-12p40 and TNFα serum levels

Epigenetic reader BRD4 supports mycobacterial pathogenesis by co-modulating host lipophagy and angiogenesis

Mycobacterium tuberculosis (Mtb)-driven lipid accumulation is intricately associated with the progression of tuberculosis (TB) disease. Although several studies elucidating the mechanisms for lipid droplet (LD) biosynthesis exist, we provide evidence for the significance of their regulated turnover via macroautophagy/autophagy during Mtb infection. We demonstrate that Mtb utilizes EGFR (epidermal growth factor receptor) signaling to induce the expression of the histone acetylation reader, BRD4 (bromodomain containing 4). The EGFR-BRD4 axis suppresses lipid-specific autophagy, and hence favors cellular lipid accumulation. Specifically, we found that pharmacological inhibition or knockdown of Egfr or Brd4 enhances autophagic flux and concomitantly decreases cellular LDs that is otherwise maintained at a significant level in chloroquine-treated or Atg5 knocked down autophagy-compromised host cells. In line with the enhanced lipophagy, we found that loss of EGFR or BRD4 function restricts mycobacterial burden that is rescued by external replenishment with oleic acid. We also report that the EGFR-BRD4 axis exerts additional effects by modulating pro-angiogenic gene expression and consequently aberrant angiogenesis during mycobacterial infection. This is important in the context of systemic Mtb dissemination as well as for the efficient delivery of anti-mycobacterial therapeutics to the Mtb-rich core of TB granuloma. Finally, utilizing an in vivo mouse model of TB, we show that pharmacological inhibition of EGFR and BRD4 compromises LD buildup via enhanced lipophagy and normalizes angiogenesis, thereby restricting Mtb burden and rescuing mice from severe TB-like pathology. These findings shed light on the novel roles of BRD4 during Mtb infection, and its possible implication in potentiating anti-TB responses.Abbreviations: ATG5: autophagy related 5; BRDs: bromodomain containing; COL18A1: collagen type XVIII alpha 1 chain; EGFR: epidermal growth factor receptor; EP300: E1A binding protein p300; KDR: kinase insert domain receptor; KLF5: Kruppel like factor 5; LDs: lipid droplets; MAP1LC3B: microtubule associated protein 1 light chain 3 beta; Mtb: Mycobacterium tuberculosis; PECAM1: platelet and endothelial cell adhesion molecule 1; SQSTM1/p62: sequestosome 1; TB: tuberculosis; THBS1: thrombospondin 1; VEGF: vascular endothelial growth factor.

Uniformity and Efficacy of Dry Powders Delivered to the Lungs of a Mycobacterial-Surrogate Rat Model of Tuberculosis

Purpose

Pulmonary administration of dry drug powder is a considered promising strategy in the treatment of various lung diseases such as tuberculosis and is more effective than systemic medication. However, in the pre-clinical study phase, there is a lack of devices for effective delivery of dry powders to the lungs of small rodents. In this study, an administration device which utilizes Venturi effect to deliver dry powders to the lungs homogeneously was developed.

Methods

A Venturi-effect administration device which synchronizes with breathes by use of a ventilator and aerosolizes the dry powders was created. Pulmonary distribution of inhalable dry powders prepared by spray-drying poly(lactic-co-glycolic) acid and an antituberculosis agent rifampicin and anti-tuberculosis effect of the powders on mycobacteria infected rats by administration with the Venturi-effect administration device and a conventional insufflation device were evaluated.

Results

Homogeneous distribution of the dry powders in the lung was achieved by the Venturi-effect administration device due to efficient and recurring aerosolization of loaded dry powders while synchronizing with breathes. Amount of rifampicin delivered to the lungs by the Venturi-effect administration device was three times higher than that by a conventional insufflation device, demonstrating three times greater antimycobacterial activity.

Conclusions

The Venturi-effect administration device aerosolized inhalable antituberculosis dry powders efficiently, achieved uniform pulmonary distribution, and aided the dry powders to exert antituberculosis activity on lung-residing mycobacteria.

Mycobacteria employ two different mechanisms to cross the blood-brain barrier

Central nervous system (CNS) infection by Mycobacterium tuberculosis is one of the most devastating complications of tuberculosis, in particular in early childhood. In order to induce CNS infection, M. tuberculosis needs to cross specialised barriers protecting the brain. How M. tuberculosis crosses the blood-brain barrier (BBB) and enters the CNS is not well understood. Here, we use transparent zebrafish larvae and the closely related pathogen Mycobacterium marinum to answer this question. We show that in the early stages of development, mycobacteria rapidly infect brain tissue, either as free mycobacteria or within circulating macrophages. After the formation of a functionally intact BBB, the infiltration of brain tissue by infected macrophages is delayed, but not blocked, suggesting that crossing the BBB via phagocytic cells is one of the mechanisms used by mycobacteria to invade the CNS. Interestingly, depletion of phagocytic cells did not prevent M. marinum from infecting the brain tissue, indicating that free mycobacteria can independently cause brain infection. Detailed analysis showed that mycobacteria are able to cause vasculitis by extracellular outgrowth in the smaller blood vessels and by infecting endothelial cells. Importantly, we could show that this second mechanism is an active process that depends on an intact ESX-1 secretion system, which extends the role of ESX-1 secretion beyond the macrophage infection cycle.

Suitability of saliva for Tuberculosis diagnosis: comparing with serum

Background

In the search for fast, simple and better ways for diagnosis of tuberculosis (TB), there is need to discover and evaluate new biomarkers that are found in samples other than sputum to determine their effectiveness. This study examined the utility of saliva vis-a-vis serum by evaluating levels of biomarkers found in saliva and serum from TB suspects.

Methods

Study enrolled tuberculosis suspects. Sputum MGIT was used as the gold standard for active TB. Quantiferon gold-In tube assay was done to identify exposure to Mycobacterium tuberculosis (M.tb). Multiplex assay was run for 10 markers using a 10 plex customized kit from Bio-Rad Laboratories.

Results

There was a significant difference between saliva and serum marker levels. Saliva had significantly higher levels of GM-CSF and VEGF. Serum had higher levels of MIP-1a, b, TNF-a, G-CSF and IFN-g. Serum levels of IL-6, VEGF and TNF-a were significantly different between participants with active TB disease and those with other respiratory diseases.

Conclusion

Salivary TB biomarkers are worth the search to evaluate their ability to differentiate between TB disease states for generation of a non invasive point of care test for TB diagnosis.

Host-directed therapy targeting the Mycobacterium tuberculosis granuloma: a review

Infection by the intracellular bacterial pathogen Mycobacterium tuberculosis (Mtb) is a major cause of morbidity and mortality worldwide. Slow progress has been made in lessening the impact of tuberculosis (TB) on human health, especially in parts of the world where Mtb is endemic. Due to the complexity of TB disease, there is still an urgent need to improve diagnosis, prevention, and treatment strategies to control global spread of disease. Active research targeting avenues to prevent infection or transmission through vaccination, to diagnose asymptomatic carriers of Mtb, and to improve antimicrobial drug treatment responses is ongoing. However, this research is hampered by a relatively poor understanding of the pathogenesis of early infection and the factors that contribute to host susceptibility, protection, and the development of active disease. There is increasing interest in the development of adjunctive therapy that will aid the host in responding to Mtb infection appropriately thereby improving the effectiveness of current and future drug treatments. In this review, we summarize what is known about the host response to Mtb infection in humans and animal models and highlight potential therapeutic targets involved in TB granuloma formation and resolution. Strategies designed to shift the balance of TB granuloma formation toward protective rather than destructive processes are discussed based on our current knowledge. These therapeutic strategies are based on the assumption that granuloma formation, although thought to prevent the spread of the tubercle bacillus within and between individuals contributes to manifestations of active TB disease in human patients when left unchecked. This effect of granuloma formation favors the spread of infection and impairs antimicrobial drug treatment. By gaining a better understanding of the mechanisms by which Mtb infection contributes to irreversible tissue damage, down regulates protective immune responses, and delays tissue healing, new treatment strategies can be rationally designed. Granuloma-targeted therapy is advantageous because it allows for the repurpose of existing drugs used to treat other communicable and non-communicable diseases as adjunctive therapies combined with existing and future anti-TB drugs. Thus, the development of adjunctive, granuloma-targeted therapy, like other host-directed therapies, may benefit from the availability of approved drugs to aid in treatment and prevention of TB. In this review, we have attempted to summarize the results of published studies in the context of new innovative approaches to host-directed therapy that need to be more thoroughly explored in pre-clinical animal studies and in human clinical trials.

Levels of interleukin-(IL)-12p40 are markedly increased in Brucellosis among patients with specific IL-12B genotypes

Brucellosis remains a major zoonosis worldwide. Brucella antigens induce the production of T-helper 1 (Th1) cytokines such as interleukin-12 (IL-12) in humans. We aimed to investigate the association of two single nucleotide polymorphisms (SNPs) in the gene encoding the IL-12p40 cytokine (IL-12B) with brucellosis and to examine the functionality of these SNPs through measuring serum levels of IL-12p40. We genotyped IL-12B gene rs3212227, A>C; rs6887695 G>C polymorphisms in a case-control study on a total of 281 subjects including 153 patients with active brucellosis and 128 healthy controls, using RFLP and serum IL-12p40 levels, were assessed by ELISA. The rs3212227 minor allele (C) and homozygote genotype (CC) were more frequent in controls compared with patients with brucellosis (P = 0.006, OR = 0.608, 95%CI = 0.429-0.861 for the C allele; P = 0.024, OR = 0.443, 95% CI: 0.218-0.900 for the CC genotype). Comparison of IL-12B genotypes and serum levels of the IL-12p40 revealed that rs3212227 AA genotype, with higher frequency in patients than in controls, was associated with increased levels of the cytokine (P = 0.0001). Furthermore, the distribution of haplotype and genotype combinations in our study suggested that rs3212227C/rs6887695C haplotype or CC/GC or CC/CC genotype combinations may protect controls against Brucella infection by contributing to a functional downregulation of the serum IL-12p40 production in vivo, as shown by ELISA (P < 0.05). Overall, our study demonstrated that rs3212227 A variant was associated with higher levels of serum IL-12p40 and could possibly contribute to an inherited predisposition to brucellosis.