Interleukin-18 promoter polymorphisms in Japanese patients with rheumatoid arthritis: protective effect of the T allele and T/T genotype at rs360722

Genetic variant of Interleukin-18 gene is associated with the Frailty Index in the English Longitudinal Study of Ageing

Background: the term frailty refers to a condition of increased vulnerability to stressors among older people, leading to a decline in homeostatic reserve. Frailty often leads to falls, hospitalisation and mortality, hence its importance for the delivery of health care to older adults. The pathophysiological mechanisms behind frailty are not well understood, but the decreased steroid-hormone production and elevated chronic systemic inflammation of older people appear to be major contributors.

Method: we used a sample of 3,160 individuals aged 50 or older from the English Longitudinal Study of Ageing and assessed their frailty status according to a Frailty Index. We selected 620 single nucleotide polymorphisms in genes involved in the steroid hormone or inflammatory pathways. We performed linear association analysis. The outcome variable was the square root transformation of the Frailty Index, with age and sex entered as covariates.

Results: the strongest signal was detected in the pro-inflammatory Interleukin-18 gene (rs360722, P = 0.0021, β = −0.015). Further significant signals were observed in the Interleukin-12 (rs4679868, P = 0.0062, β = −0.008 and rs9852519, P = 0.0077, β = −0.008), low density lipoprotein receptor-related protein 1 (rs1799986, P = 0.0065, β = 0.011) and Selectin-P (rs6131, P = 0.0097, β = −0.01) genes. None of these associations remain significant after Bonferroni correction.

Conclusions: we show potential associations between genetic variants of four genes and the frailty index. These genes are involved in the cholesterol transport and inflammatory pathway and, as such, our results provide further support for the involvement of the immunological processes in frailty of the elderly.

Interleukins and interleukin receptors in rheumatoid arthritis: Research, diagnostics and clinical implications

Rheumatoid arthritis (RA) is an autoimmune disease, resulting in a chronic, systemic inflammatory disorder. It may affect many tissues and organs, but it primarily affects the flexible joints. In clinical practice patient care generates many questions about diagnosis, prognosis, and treatment. It is challenging for health care specialists to keep up to date with the medical literature. This review summarizes the pathogenesis, the polymorphisms of interleukin and interleukin genes and the standard available and possible future immunologic targets for RA treatment. The identification of disease-associated interleukin and interleukin receptor genes can provide precious insight into the genetic variations prior to disease onset in order to identify the pathways important for RA pathogenesis. The knowledge of the complex genetic background may prove useful for developing novel therapies and making personalized medicine based on the individual’s genetics.

Association of IL-18 promoter gene polymorphisms with rheumatoid arthritis: a meta-analysis

Interleukin-18(IL-18) plays a potential pathological role in rheumatoid arthritis (RA). The conclusions of the published reports on the relationship between single-nucleotide polymorphisms -607C/A (rs1946518) and -137G/C (rs187238) located in the IL-18 gene promoter and RA risk remain controversial. This meta-analysis was performed to evaluate the association between IL-18 gene promoter (-607A/C and -137C/G) polymorphisms and RA using (1) allele, (2) codominant, (3) dominant, and (4) recessive models. Literature search was conducted up to January, 2013, in PubMed, EMBASE, Spring-link, Web of Science, Wanfang (Chinese) and China National Knowledge Infrastructure (CNKI). A total of 10 studies from eight articles involving 2,662 cases and 2,168 controls for -607A/C polymorphism and 9 studies from six articles involving 1,331 cases and 1,468 controls for -137C/G polymorphism were considered in the meta-analysis. For the relationship of IL-18 -607A/C polymorphism with RA risk, significant association was observed in allele model (OR = 0.778, 95 % CI = 0.633-0.955) and dominant model (OR = 0.618, 95 % CI = 0.466-0.819). However, no significant association could be observed between -137C/G polymorphism and RA risk under all genetic models (allele model: OR = 0.940, 95 % CI = 0.777-1.138; codominant model: OR = 1.079, 95 % CI = 0.574-2.029; dominant model: OR = 0.913, 95 % CI = 0.779-1.069; recessive model: OR = 1.133, 95 % CI = 0.586-2.190). In the subgroup analysis by ethnicity, significant result was also found in Asian populations but not found in Caucasian populations for the relationship of IL-18 -607A/C polymorphism with RA risk; while no obvious association was found between IL-18 -137C/G polymorphism and RA risk. This meta-analysis indicates that IL-18 -607A/C polymorphism in promoter region may be associated with RA risk.

Association of IL-18 polymorphisms with rheumatoid arthritis and systemic lupus erythematosus in Asian populations: a meta-analysis

BACKGROUND

Interleukin (IL)-18, an important proinflammatory cytokine, plays a potential pathological role in rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE). Studies on the relationship of IL-18 gene promoter rs1946518 (-607A/C) polymorphism, rs187238 (-137G/C) polymorphism with RA and SLE are inconclusive. The aim of this study was to get a more precise estimation of the relationship in Asian populations.

METHODS

Meta-analysis was conducted on the associations between the IL-18 (-607A/C and -137G/C) polymorphisms and RA and SLE, using; (1) allele contrast, (2) dominant, and (3) recessive models. A total of 11 studies were included in this study.

RESULTS

For the relationship of IL-18 rs1946518 polymorphism with RA (additive model: OR=0.752, 95%CI=0.562-1.006; dominant model: OR=0.730, 95%CI =0.479-1.113; recessive model: OR=0.537, 95%CI=0.271-1.064) and SLE (additive model: OR=0.684, 95%CI=0.455-1.028; dominant model: OR=0.645, 95%CI=0.368-1.130; recessive model: OR=0.672, 95%CI =0.447-1.010), no significant association with RA and SLE risk can be found under all genetic models in Asian populations. However, significant associations were observed in Chinese population for both RA ((OR=0.688, 95%CI =0.532-0.889) and SLE (OR=0.606, 95%CI =0.396-0.930) under additive model. For the relationship between IL-18 rs187238 polymorphism and RA or SLE, there was no significant association detected in all genetic models, even in Chinese population.

CONCLUSIONS

This meta-analysis indicates that the IL-18-607A/C polymorphism may confer susceptibility to RA and SLE in Chinese population, but not all Asians.