Influence of genetic variants of gamma interferon, interleukins 10 and 12 on Visceral Leishmaniasis in an endemic area, Iran

Human visceral leishmaniasis and polymorphisms in interleukin-coding genes: a systematic review

Visceral leishmaniasis (VL) is a neglected disease that is typical of tropical and subtropical parts of the world and is caused by the trypanosomatid Leishmania donovani complex. This disease is a multifactorial condition that involves parasitic, environmental, and immunogenetic characteristics. Genetic changes in genes encoding cytokines may be associated with changes in their expression and, consequently, with the development of clinical resistance or susceptibility to the disease. This systematic review and meta-analysis aimed to assess whether single nucleotide polymorphisms (SNPs) in interleukin genes influence the clinical consequences of visceral leishmaniasis infection. To this end, we carried out a systematic review and meta-analysis with structured searches in the EMBASE, PubMed, Scopus, SciELO, and Web of Science databases without time restrictions. Two independent reviewers examined the studies, performed data extraction, and assessed quality by assigning scores. If there were any discrepancies, a third reviewer with more experience was consulted. After the screening process, 28 articles were included in the systematic review and 9 in the final analysis of the meta-analysis. Statistical analyses were carried out using various genetic models. The odds ratio (OR) and corresponding 95% confidence intervals (CIs) were calculated to estimate the associations. Overall, the main clinical outcomes were classified as not associated or associated when they presented susceptibility, resistance, risk, or protective factors for the development of the disease. Associations between IFN-γ +874T/A polymorphisms in the dominant model (OR 1.64, 95% CI 1.13-2.38, I2 = 0%, p < 0.01) and heterozygous model (OR 1.72, 95% CI 1.15-2.57, I2 = 0%, p < 0.01) and IL-18 -137G/C in the recessive model (OR 1.33, 95% CI 1.02-1.71, I2 = 9%, p = 0.03) and VL were observed. For the IL-10 gene SNPs, there was no significant association. Our findings suggest that SNPs in the IFN-γ and IL-18 genes may be associated with the risk of developing VL.

Cytokines signatures and susceptibility to cutaneous leishmaniasis in patients from Sistan and Baluchestan province of Iran

BACKGROUND

Cutaneous leishmaniasis (CL) is a complex, multifactorial disease that results from environmental factors such as parasite polymorphism, phlebotomine vectors, and host genetic factors. Some studies have identified specific genetic factors that may be associated with cutaneous leishmaniasis. The objective of this research was to resolve the association of 8 cytokine polymorphisms, including TNF-α -308 A/G (rs 1800629), TNF-α -238 A/G (rs 361525), TGF-β1 -509 T/C (rs 1800469), TGF-β1+ 915 G/C (rs 1800471), IFN-γ -874 T/A (rs 2430561), IFN-γ -179 G/A (rs 2069709), IL-10 -819 C/T (rs 1800871), and IL-10 -592 A/C (rs 1800872) with susceptibility to CL.

METHODS

A total of 152 patients with designated CL and 100 healthy controls were selected from those referred to Sistan and Baluchestan hospitals. CL was diagnosed by microscopic examination of Giemsa-stained samples and culture. Leishmania species were identified using ITS2 gene PCR amplification with universal primers. Genetic polymorphism was determined by the ARMS PCR method on extracted genomic DNA of individuals. Eight SNPs cytokines were genotyped.

RESULTS

Most of the Genotypic and allelic frequency comparisons between patients with CL and healthy subjects showed no difference, except 3. Individual SNP analysis showed highest association of TGF-β1 -509 (rs1800469) -CC genotype (P = 0.03, OR = 7.05, 95 % CI = 3.3-15) with 5.7-fold increase, IFN-γ -874 (rs 2430561) -AA genotype (P = 0.04, OR = 4.72, 95 % CI = 1.6-14) with 4.2-fold increase, and IL10 -819 (rs1800871) -CC genotype (P = 0.05, OR = 3.63, 95 % CI = 2.5-5.3) with 1.9-fold increase, with CL. Odds ratios (ORs) and 95 % confidence intervals (CIs) were evaluated to assess the association power.

CONCLUSION

Our results conclude that rs1800469 (TGF-β1), rs2430561 (INF-γ), and rs1800872 (IL10) polymorphisms are associated with CL in southeastern Iranian people.

Interleukin 6 and interferon gamma haplotypes are related to cytokine serum levels in dogs in an endemic Leishmania infantum region

BACKGROUND

The Ibizan Hound is a canine breed native to the Mediterranean region, where leishmaniasis is an endemic zoonosis. Several studies indicate a low prevalence of this disease in Ibizan Hound dogs, whereas other canine breeds present a high prevalence. However, the underlying molecular mechanisms still remain unknown. The aim of this work is to analyse the relationship between serum levels of cytokines and the genomic profiles in two canine breeds, Ibizan Hound (resistant canine breed model) and Boxer (susceptible canine breed model).

METHODS

In this study, we analyse the haplotypes of genes encoding cytokines related to immune response of Leishmania infantum infection in twenty-four Boxers and twenty-eight Ibizan Hounds apparently healthy using CanineHD DNA Analysis BeadChip including 165,480 mapped positions. The haplo.glm extension of haplo.score was used to perform a General Linear Model (GLM) regression to estimate the magnitude of individual haplotype effects within each cytokine.

RESULTS

Mean levels of interferon gamma (IFN-γ), interleukin 2 (IL-2) and IL-18 in Boxer dogs were 0.19 ± 0.05 ng/ml, 46.70 ± 4.54 ng/ml, and 36.37 ± 30.59 pg/ml, whereas Ibizan Hound dogs present 0.49 ± 0.05 ng/ml, 64.55 ± 4.54 ng/ml, and 492.10 ± 31.18 pg/ml, respectively. The GLM regression shows fifteen haplotypes with statistically significant effect on the cytokine serum levels (P < 0.05). The more relevant are IL6-CGAAG and IFNG-GCA haplotypes, which increase and decrease the IL-2, IL-8 and IFN-γ serum levels, respectively.

CONCLUSIONS

Haplotypes in the IFNG and IL6 genes have been correlated to serum levels of IFN-γ, IL-2 and IL-18, and a moderate effect has been found on IL8 haplotype correlated to IL-8 and IL-18 serum levels. The results indicate that the resistance to L. infantum infection could be a consequence of certain haplotypes with a high frequency in the Ibizan Hound dog breed, while susceptibility to the disease would be related to other specific haplotypes, with high frequency in Boxer. Future studies are needed to elucidate whether these differences and haplotypes are related to different phenotypes in immune response and expression gene regulation to L. infantum infections in dogs and their possible application in new treatments and vaccines.

Human genetic polymorphism and Leishmaniasis

Leishmaniasis is a disease of the subtropical and tropical spheres of the earth and has various clinical manifestations. The different form of leishmaniasis includes cutaneous leishmaniasis, mucocutaneous leishmaniasis, most lethal visceral leishmaniasis and PKDL form. These different forms depend on many factors such as parasite and vector species, geographical, environmental conditions and population ethnicity. Host genetic factors have been widely investigated for their role in developing the disease in various infections. There are several reports on associations or resistance between candidate gene polymorphisms and the risk and outcome of Leishmania infection. Polymorphism in genes involved in both innate and adaptive immune systems, as well as genes of metabolic processes contributes to disease manifestation. The wide availability and advancement of molecular techniques permits to exploration of hereditary factors related to leishmaniasis. Many candidate gene studies were conducted on family-based and population to identify novel biomarkers for understanding disease pathogenesis pathways and possible drug targets. This comprehensive review presents an update on various human genes polymorphism that influence the outcome of different forms of Leishmania infection in endemic regions of the world. Various electronic databases were searched systematically for relevant publications and thoroughly analyzed. Most of the candidate gene studies were found with discrepancies in findings. Genetic and functional studies with adequate power are needed to validate the contribution of host genes in susceptibility or resistance towards Leishmania infection and understanding pathogenesis.

Exploring the Links between Personality and Immune Function

Decades of research finds associations between personality traits and health. In recent years, it has become clear that the activities of the immune system play a key role in linking these variables. In the current work, we add to this research by exploring the relationship between Big Five personality traits and (Study 1) polymorphisms known to impact cytokine release and (Study 2) immunological parameters measured in vivo (differential white blood cell counts, plasma proinflammatory cytokine levels) and in vitro (proinflammatory cytokine release by peripheral blood mononuclear cells, Staphylococcus aureus growth in plasma). Results provide insights into potential mechanistic drivers of the link between personality and immune function and the possibility that, in some cases, relationships between personality and immune function may be sex differentiated.

A historical review of the role of cytokines involved in leishmaniasis

Leishmaniasis is an infectious disease caused by the Leishmania genus, affecting millions of persons in the world. Despite increased studies, no vaccine has been developed against leishmaniasis, and drug resistance is evolving in some Leishmania species (spp). Innate and acquired immune cells and their associated cytokines interplay together to determine the immune responses related outcomes in leishmaniasis. Interferon (IFN)-γ or macrophage activating factor (MAF) is the first effective lymphokine (LK), with a related function to leishmaniasis, discovered in 1979. This review article discussed the history of cytokines involved in Leishmania infection, and it is the first report demonstrating the involvement in the disease by focusing on cutaneous leishmaniasis. Up to now, the role of many cytokines has been determined and the literature review showed that IL-35 is the latest known cytokine involved in leishmaniasis. This review revealed that the cytokines have pleiotropic effects, depending upon the cytokine environment, generated during the infection and the host genetic background or infecting Leishmania spp. Overall, advances in our knowledge of immune cells and their secreted cytokines, contributing to the protection or pathological process of leishmaniasis may help to reach new approaches for immunotherapy.

Association of cytokine gene polymorphisms with susceptibility to cutaneous leishmaniasis in a Turkish population

AIMS

The objective of this study was to determine the association of TNF-α -308 G/A, IFN-γ +874 T/A, IL-12B + 1188 A/C, IL-10 -1082 G/A and IL-4 -590 C/T polymorphisms with susceptibility to CL.

METHODS AND RESULTS

A total of 55 CL patients and 110 controls from Sanlıurfa province of Turkey were included to this study. Polymorphisms were genotyped by 'polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP)' and 'amplification refractory mutation system-PCR (ARMS-PCR)' methods. A statistically significant difference was noted in the allele (P < .001, P = .002) and genotype (P < .001, P = .001,) frequencies of TNF-α -308 G/A and IL-4 -590 C/T, respectively. TNF-α 308 GG versus GA genotype (OR = 19.556 [95% CI 8.310-46.019] P < .001), GG versus GA + AA genotype (OR = 20.444 [95% CI 8.707-48.004] P < .001) and G versus A allele (OR = 6.968 [95% CI 3.903-12.440] P < .001) revealed significant association with CL. IL-4 -590 CC versus TT + CT genotype (OR = 2.049 [95% CI 1.025-4.096], P = .041) and C versus T allele (OR = 2.441 [95% CI 1.355-4.396], P = .002) revealed significant association with CL.

CONCLUSION

Our study indicates that TNF-α 308 G/A and IL-4-590 C/T polymorphisms are significantly associated with susceptibility to CL. Individuals carrying A allele at TNF-α promoter -308 position and T allele at IL-4 promoter -590 position are at a higher risk for CL.

Association of Single Nucleotide Polymorphisms of the IL-6, IL-10, and TNF-α Genes with Susceptibility to Gestational Diabetes Mellitus

Objective: To investigate any associations between the single nucleotide polymorphisms (SNPs) at the interleukin-6 (IL-6) rs1800796, interleukin-10 (IL-10) rs1800896, and the tumor necrosis factor-alpha (TNF-α) rs1800629 loci with gestational diabetes mellitus (GDM) susceptibility. Materials and Methods: A total of 242 GDM patients and 242 healthy controls were enrolled in this study. The genotypes of the IL-6 rs1800796, IL-10 rs1800896, and TNF-α rs1800629 loci were analyzed by Sanger sequencing. Interactions among these SNPs were analyzed through multifactor dimensionality reduction. Results: Women with the IL-6 rs1800796 G allele had a higher GDM susceptibility risk than those with the C allele (odds ratio [OR] = 1.44, 95% confidence interval [CI]: 1.10-1.90, p = 0.010). Women with the IL-10 rs1800896 C allele had a higher risk of GDM susceptibility than those with the T allele (OR = 2.94, 95% CI: 1.87-4.63, p < 0.001). Women with the TNF-α rs1800629 A allele had a higher risk of susceptibility to GDM than those with the G allele (OR = 3.73, 95% CI: 2.25-6.18, p < 0.001). The plasma levels of IL-6 and TNF-α in GDM patients were significantly higher than those in the control group, and the levels of IL-10 were significantly lower than those in the control group (p < 0.001). Women with the IL-6 rs1800796 CG/GG genotypes had higher plasma IL-6 levels than those with the CC genotype (p < 0.05). Women with the IL-10 rs1800896 TT genotype had higher IL-10 levels than those with the TC/CC genotypes (p < 0.05), and those with the TNF-α rs1800629 GA/AA genotypes had higher TNF-α levels than those with the GG genotype (p < 0.05). Conclusion: The results of this study show that the IL-6 rs1800796 G allele, the IL-10 rs1800896 C allele, and the TNF-α rs1800629 A allele are significantly associated with an increased risk of susceptibility to GDM.

Cytokines: Key Determinants of Resistance or Disease Progression in Visceral Leishmaniasis: Opportunities for Novel Diagnostics and Immunotherapy

Leishmaniasis is a parasitic disease of humans, highly prevalent in parts of the tropics, subtropics, and southern Europe. The disease mainly occurs in three different clinical forms namely cutaneous, mucocutaneous, and visceral leishmaniasis (VL). The VL affects several internal organs and is the deadliest form of the disease. Epidemiology and clinical manifestations of VL are variable based on the vector, parasite (e.g., species, strains, and antigen diversity), host (e.g., genetic background, nutrition, diversity in antigen presentation and immunity) and the environment (e.g., temperature, humidity, and hygiene). Chemotherapy of VL is limited to a few drugs which is expensive and associated with profound toxicity, and could become ineffective due to the parasites developing resistance. Till date, there are no licensed vaccines for humans against leishmaniasis. Recently, immunotherapy has become an attractive strategy as it is cost-effective, causes limited side-effects and do not suffer from the downside of pathogens developing resistance. Among various immunotherapeutic approaches, cytokines (produced by helper T-lymphocytes) based immunotherapy has received great attention especially for drug refractive cases of human VL. Therefore, a comprehensive knowledge on the molecular interactions of immune cells or components and on cytokines interplay in the host defense or pathogenesis is important to determine appropriate immunotherapies for leishmaniasis. Here, we summarized the current understanding of a wide-spectrum of cytokines and their interaction with immune cells that determine the clinical outcome of leishmaniasis. We have also highlighted opportunities for the development of novel diagnostics and intervention therapies for VL.