IL-18 polymorphisms and tuberculosis susceptibility: a meta-analysis

TARM-1 Is Critical for Macrophage Activation and Th1 Response in Mycobacterium tuberculosis Infection

T cell-interacting activating receptor on myeloid cells 1 (TARM-1) is a novel leukocyte receptor expressed in neutrophils and macrophages. It plays an important role in proinflammatory response in acute bacterial infection, but its immunomodulatory effects on chronic Mycobacterium tuberculosis infections remain unclear. TARM-1 expression was significantly upregulated on CD14^high monocytes from patients with active pulmonary tuberculosis (TB) as compared that on cells from patients with latent TB or from healthy control subjects. Small interfering RNA knockdown of TARM-1 reduced expression levels of proinflammatory cytokines IL-12, IL-18, IL-1β, and IL-8 in M. tuberculosis-infected macrophages, as well as that of HLA-DR and costimulatory molecules CD83, CD86, and CD40. Moreover, TARM-1 enhanced phagocytosis and intracellular killing of M. tuberculosis through upregulating reactive oxygen species. In an in vitro monocyte and T cell coculture system, blockade of TARM-1 activity by TARM-1 blocking peptide suppressed CD4⁺ T cell activation and proliferation. Finally, administration of TARM-1 blocking peptide in a mouse model of M. tuberculosis infection increased bacterial load and lung pathology, which was associated with decreased macrophage activation and IFN-γ production by T cell. Taken together, these results, to our knowledge, demonstrate a novel immune protective role of TARM-1 in M. tuberculosis infection and provide a potential therapeutic target for TB disease.

Interleukin-18 and interferon-γ single nucleotide polymorphisms in Egyptian patients with tuberculosis

BACKGROUND

Interleukin-18 (IL-18) and interferon-γ (IFN-γ) are cytokines of crucial role in inflammation and immune reactions. There is a growing evidence supporting important roles for IL-18 and IFN γ in tuberculosis (TB) infection and anti-tuberculosis immunity.

OBJECTIVE

To evaluate the role of polymorphisms in IL-18-607 and -137 and INF-γ +874 in susceptibility to TB infection among Egyptian patients.

METHODS

A case control study was conducted to investigate the polymorphism at IL-18-607, -137 and INF-γ+874 by sequence specific primer-polymerase chain reaction (SSP- PCR) in 105 patients with pulmonary and extra pulmonary tuberculosis and 106 controls.

RESULTS

A significant protective effect against TB was found in homozygous CC genotype at IL-18 -137G/C, in addition to a 7-fold risk with GG and GC genotypes in the recessive model. Apart from a decreased risk with the AC genotype, no association was detected between the susceptibility to TB and different genotypes or alleles at the IL-18 -607A/C site. The homozygous AA genotype in INF-γ+874 showed a significant higher risk to TB than the homozygous TT or heterozygous AT genotypes with nearly a 2-fold risk of TB infection with the A allele. Regarding haplotype association, the GC haplotype was strongly associated with TB infection compared to other haplotypes.

CONCLUSION

These findings suggest; for the first time in Egypt; a significant risk to TB infection with SNP at the IL-18-137G/C with no LD with SNP at the IL-18-607 site. The homozygous AA genotype in INF-γ+874 showed a significant higher risk to TB than the homozygous TT or heterozygous AT genotypes.

Association between interleukin-8 -251A/T polymorphism and the risk of tuberculosis: A meta-analysis

Objective

The relationship between interleukin-8 (IL8) −251A/T polymorphism and tuberculosis (TB) risk remains controversial. Therefore, the present meta-analysis was performed by retrieving relevant studies from the available literature.

Methods

We comprehensively searched three databases to identify eligible literature on the relationship of IL8 −251A/T polymorphism with TB risk, calculated pooled odds ratios (OR) with 95% confidence intervals (CI), and subsequent evaluated the heterogeneity and publication bias.

Results

We found that IL8 −251A/T polymorphism increased TB risk (AA vs. TT: OR = 2.86, 95%CI: 1.46–5.60; AT vs. TT: OR = 1.64, 95%CI: 1.15–2.34; dominant model: OR = 1.88, 95%CI: 1.24–2.86; recessive model: OR = 1.77, 95%CI: 1.17–2.69). Subgroup analyses based on race revealed that the IL8 −251A/T polymorphism might be associated with the risk of TB in African but not Asian individuals.

Conclusion

The IL8 −251A/T polymorphism might be related to the risk of TB. Nevertheless, large-scale studies should be performed to confirm the role of IL8 −251A/T polymorphism on TB risk.