Ex vivo innate immune cytokine signature of enhanced risk of relapsing brucellosis

Brucella abortus and Pregnancy in Mice: Impact of Chronic Infection on Fertility and the Role of Regulatory T Cells in Tissue Colonization

Stealthy intracellular bacterial pathogens are known to establish persistent and sometimes lifelong infections. Some of these pathogens also have a tropism for the reproductive system, thereby increasing the risk of reproductive disease and infertility. To date, the pathogenic mechanism involved remains poorly understood. Here, we demonstrate that Brucella abortus, a notorious reproductive pathogen, has the ability to infect the nonpregnant uterus, sustain infection, and induce inflammatory changes during both acute and chronic stages of infection. In addition, we demonstrated that chronically infected mice had a significantly reduced number of pregnancies compared to naive controls. To investigate the immunologic mechanism responsible for uterine tropism, we explored the role of regulatory T cells (Tregs) in the pathogenesis of Brucella abortus infection. We show that highly suppressive CD4+FOXP3+TNFR2+ Tregs contribute to the persistence of Brucella abortus infection and that inactivation of Tregs with tumor necrosis factor receptor II (TNFR2) antagonistic antibody protected mice by significantly reducing bacterial burden both systemically and within reproductive tissues. These findings support a critical role of Tregs in the pathogenesis of persistence induced by intracellular bacterial pathogens, including B. abortus Results from this study indicate that adverse reproductive outcomes can occur as sequelae of chronic infection in nonpregnant animals and that fine-tuning Treg activity may provide novel immunotherapeutic and prevention strategies against intracellular bacterial infections such as brucellosis.

Association of IL-6, IL-10 and TGF-β1 gene polymorphisms with brucellosis: A systematic review with meta-analysis

BACKGROUND

Brucellosis is one of the major public health problems worldwide. Several current studies have provided data that polymorphisms in the interleukin-6 (IL-6), interleukin-10 (IL-10) and transforming growth factor beta1(TGF-β1) gene were associated with the susceptibility to human brucellosis, but the results remain inconsistent.

OBJECTIVES

The aim of present study was to investigate the relationship between IL-6 (-174 G/C), IL-10 (-1082 A/G, -819C/T) and TGF-β1 (codon 10, codon 25) gene polymorphisms and brucellosis.

METHODS

We performed a comprehensive search of the PubMed, EMBASE, Web of Science, OVID-EBMR, and the Cochrane Library up to Oct. 30, 2018. The search was designed using the following key words: "brucellosis" or" "brucella melitensis", "IL-10" or "interleukin10" or "interleukin-10", "IL-6" or "interleukin6" or "interleukin-6", "TGF-β1" or "TGF-beta1" or "transforming growth factor β1", "polymorphism" and "single nucleotide polymorphism (SNP)". Crude odds ratios (ORs) with 95% confidence intervals (CIs) were used to measure the strength of association between TGF-β1, IL-10 and IL-6 polymorphisms and brucellosis risk. All the statistical analyses were conducted by Review manager 5.3 software.

RESULTS

A total of 8 studies involving 1308 cases and 902 controls met the inclusion criteria for IL-6, IL-10, TGF-β1 polymorphisms and brucellosis risk. There was a slightly trend of increasing risk of brucellosis in individuals with the G allele compared with individuals with the C allele (OR = 1.07, 95% CI: 0.85-1.33, P = 0.57) in IL-6 polymorphism. However, statistical analysis showed that these differences are not significant. Our results suggested TGF-β1 (codon 25 G/C) GG genotype may be considered as a risk factor for brucellosis (OR = 1.67, 95% CI: 1.12-2.50, P = 0.01). Herein, we failed to find any significant association between IL-10 (-1082 A/G, -819C/T), TGF-β1 (codon 10C/T) gene polymorphism and susceptibility to brucellosis in all gene models.

CONCLUSION

IL-6 (-174 G/C), IL-10 (-1082 A/G, -819C/T), and TGF-β1 (codon 10C/T) polymorphisms is not a risk factor for brucellosis infection. TGF-β1 codon 25 GG genotype may be considered as a risk factor for brucellosis.

The IL4-VNTR P1 Allele, IL4-VNTR P2P2 Genotype, and IL4-VNTR_IL6-174CG P2P1-GG Genotype Are Associated with an Increased Risk of Brucellosis

In this study, associations between IL-4, IL-6, and macrophage migration inhibitory factor (MIF) polymorphisms and susceptibility to brucellosis were investigated. Consecutive adult patients with no known treatment against brucellosis and who did not have any other autoimmune and/or chronic disorders, were included in this study (n = 120, Group I). Age and sex-matched controls who had no other autoimmune and/or chronic disorders were also included (n = 120, healthy volunteers, Group II). The IL4_P2P2 genotype, IL4_P1 allele, and IL4_variable number of tandem repeats (VNTR)_IL6-174CG compound genotype were found to be more frequent in the patient group than in control subjects. There were significant differences between the patients and controls with respect to the frequencies of the IL4_P2P2 genotype (77.5% versus 87.5%; p = 0.001; OR, 0.36; 95% confidence interval [CI], 0.21-0.62) and the IL4_P1 allele (12.1% versus 6.7%; p = 0.030; OR, 0.92; CI, 1.02-3.64). The IL4-VNTR_IL6-174CG compound genotype was also present at a significantly higher frequency in the patient group than in control subjects (11.7% versus 4.2%; p = 0.027, OR, 3.04; CI, 1.06-8.68). No statistically significant differences in the frequencies of the IL-6-174, MIF-173, IL-4_P1P1, and IL4_P2P1 genotypes were observed between patients and control subjects. The IL4_VNTR P1 allele, P2P2 genotypes, and IL4-VNTR_IL6-174CG P2P1-GG genotypes are common in southern Turkey, and carriers of these polymorphisms are susceptible to brucellosis.

TNF-α -238, -308, -863 polymorphisms, and brucellosis infection

BACKGROUND

Brucella abortus is an intracellular bacterium that affects humans and domestic animals. Tumor necrosis factor-alpha (TNF-α) has been shown as a key player in the induction of cell-mediated resistance against Brucella infection. We aimed to evaluate the possible influence of the TNF-α promoter polymorphisms (-308 G/A, -238 G/A, and -863 C/A) on the susceptibility of human brucellosis.

METHODOLOGY

A total of 153 patients with active brucellosis and 128 healthy individuals were recruited. All subjects were genotyped for the polymorphisms in the TNF-α gene by Allele-Specific polymerase chain reaction analysis.

RESULTS

Our results showed that the TNF-α -308 GG genotype was significantly more frequently present in controls than in brucellosis patients (91% vs. 75%), thus was a protective factor against developing brucellosis (OR=0.313, p=0.001). In contrast, the -308 GA genotype (OR=3.026, p=0.002) and minor allele (A) (OR=3.058, p=0.001) as well as AAG haplotype (OR=4.014, p=0.001) conferred an increased risk of brucellosis. However, the -238 G/A and -863 C/A polymorphisms were not associated with the risk of brucellosis at both allelic and genotypic levels (p>0.05).

CONCLUSION

Our study revealed that the TNF-α -308 A allele or GA heterozygosity or AAG haplotype were associated with an increased risk of brucellosis in our population.