IL-10 Overexpression After BCG Vaccination Does Not Impair Control of Mycobacterium tuberculosis Infection

Association of TOLLIP mRNA Expression and TOLLIP rs5743899A/G, TOLLIP rs3750920C/T, and IL-10 -1082G/A Single-Nucleotide Polymorphisms with Susceptibility to Tuberculosis

The early innate host immune response is crucial in the susceptibility to tuberculosis (TB). This study aimed to investigate the potential role of Toll-interacting protein (TOLLIP), a negative regulator of the human innate immune response, and interleukin-10 (IL-10), an anti-inflammatory cytokine, in susceptibility to TB. The peripheral blood mononuclear cells of 30 active pulmonary TB patients and 30 healthy volunteers were included. TOLLIP mRNA expression levels, single nucleotide polymorphisms (SNPs) of the TOLLIP gene, such as rs5743899A/G and rs3750920C/T, and IL-10 -1082G/A SNP were detected using real-time PCR, PCR-restriction fragment length polymorphism (PCR-RFLP) and amplification refractory mutation system-PCR (ARMS-PCR), respectively. TOLLIP mRNA expression levels were significantly higher in TB patients than in healthy controls (expression fold difference = 2.72, the delta-delta Ct method, also known as the 2-∆∆Ct method). The heterozygous (GA) genotype of the IL-10 -1080G/A polymorphism was significantly predominant among the patient group (p = 0.02, Hardy-Weinberg equilibrium). However, the Kruskal‒Wallis analysis found no significant relationship between TOLLIP mRNA expression levels and SNPs. TOLLIP mRNA and IL-10 -1082G/A SNP were assessed as potential biomarkers to predict TB susceptibility. For more significant results, they should be examined with other negative regulators of innate immunity and other immune factors associated with susceptibility to TB. Our study is the first to investigate the association of TOLLIP polymorphisms and expression levels with TB susceptibility in Turkey.

IL-27 alters inflammatory cytokine expression and limits protective immunity against Mycobacterium tuberculosis in a neonatal BCG vaccination model

Background

Efforts to control tuberculosis (TB), caused by the pathogen Mycobacterium tuberculosis (Mtb), have been hampered by the immense variability in protection from BCG vaccination. While BCG protects young children from some forms of TB disease, long-term protection against pulmonary disease is more limited, suggesting a poor memory response. New vaccines or vaccination strategies are required to have a realistic chance of eliminating TB disease. In TB endemic areas, routine immunization occurs during the neonatal period and as such, we hypothesized that inadequate protective immunity elicited by BCG vaccination could be the result of the unique early-life immune landscape. Interleukin (IL)-27 is a heterodimeric cytokine with immune suppressive activity that is elevated in the neonatal period.

Objective

We investigated the impact of IL-27 on regulation of immune responses during neonatal BCG vaccination and protection against Mtb.

Methods

Here, we used a novel model of neonatal vaccination and adult aerosol challenge that models the human timeline of vaccine delivery and disease transmission.

Results

Overall, we observed improved control of Mtb in mice unresponsive to IL-27 (IL-27Rα-/-) that was consistent with altered expression patterns of IFN-γ and IL-17 in the lungs. The balance of these cytokines with TNF-α expression may be key to effective bacterial clearance.

Conclusions

Our findings suggest the importance of evaluating new vaccines and approaches to combat TB in the neonatal population most likely to receive them as part of global vaccination campaigns. They further indicate that temporal strategies to antagonize IL-27 during early life vaccination may improve protection.

Bacillus Calmette-Guérin-induced interleukin-10 inhibits S100A8/A9 production and hinders development of T helper type 1 memory in mice

Tuberculosis caused by Mycobacterium tuberculosis (M.tb) is one of the main causes of human death in the world. Bacillus Calmette-Guérin (BCG) provides limited protection in adolescents and adults. To explore the factors reducing efficacy of BCG vaccine, we assess the impacts of interleukin (IL)-10 and alarmins S100A8/A9 on T-cell memory. We found that BCG-induced IL-10 inhibited production of S100A8/A9 in human peripheral blood mononuclear cells (PBMCs) and murine splenocytes. S100A9 deficiency inhibited IFN-γ production by CD4⁺ T cells in the early phase of BCG immunization and hindered the development of effector memory T helper type 1 (Th1) cells, while IL-10 deficiency promoted Th1 memory and blocking IL-10 signaling enhanced Th1 protective recall response against M.tb. IL-10 inhibited the binding of transcription factor CCAAT enhancer binding protein beta to S100a8/a9 promoter leading to S100A8/A9 reduction. S100A8/A9 heterodimer enhanced the IFN-γ production via receptor for advanced glycation end products signaling in CD4⁺ T cells. Our results demonstrate a hurdle to development of Th1 memory after BCG immunization and clarify the mechanism of the regulation of Th1 memory by IL-10 and S100A8/A9.