Contents lists are available at the SciVerse ScienceDirect Cytokine journal homepage: www.elsevier.com/locate/issn/10434666. Although persistent inflammation has been related to unsuccessful aging, a pro-inflammatory status is a common phenotype in older individuals. To assess the genetic component of the inflammatory status in the elderly, we studied the distribution of two polymorphic chemokine pathway genes, RANTES and CCR5, in the elderly. We genotyped RANTES (cid:2)403G/A and RANTES Int1.1T/C polymorphisms and CCR5D32 polymorphism in 104 elderly individuals and 110 controls. The RANTES (cid:2)403A and RANTES Int1.1C alleles are associated with pro-inflammatory and anti-inflammatory status, respectively. The CCR5D32 allele abrogates functional receptor expression of the pro-inflammatory CCR5-mediated action. The prevalence of the RANTES (cid:2)403G allele, which is associated with high RANTES production in other studies, was reduced in elderly males compared to controls. In addition, the RANTES pro-inflammatory haplotype (cid:2)403A-Int1.1T was overrepresented in elderly males, while the RANTES anti-inflammatory haplotype (cid:2)403G-Int1.1C was overrepresented in elderly females. Our results suggest a sex-specific RANTES inflammatory genetic determinant that could contribute to the known sex-related differences in aging.    2012 Elsevier Ltd. All rights reserved.

Introduction

Recruitment of leukocytes to an inflammation site is related to chemokine gene transcription and receptor expression levels due to polymorphisms at the corresponding genes that affect inflammatory response. Previous studies of chemokine factors related to age-related disease and longevity revealed attrition or change in frequency of chemokine alleles with aging. Chemokines are small chemotactic cytokines (C-C) with a pivotal role in leukocyte trafficking and activation. Their biological effects are exerted via interaction with G protein-coupled receptors that mediate intracellular signals. C-C chemokine receptor type 5 (CCR5) is the co-receptor for macrophages and dual (T cell and macrophage) tropic immunodeficiency viruses and is involved in the migration of monocytes, NK cells, and Th1 cells toward an increasing concentration of b-chemokines, which results in recruitment of leukocytes to the inflammation site. Natural CCR5 ligands are the C-C motif chemokine ligands CCL3, CCL4, and CCL5, which are also known as RANTES (regulated upon activation normal T-cell expressed and secreted). Two polymorphisms have been described in the RANTES gene, a promoter polymorphism ((cid:2)403G/A, rs2107538) whose (cid:2)403A allele increases the promoter transcriptional activity, which results in high serum RANTES levels favoring a pro-inflammatory status [4], and an intronic polymorphism (Int1.1T/C, rs2280789) whose Int1.1C variant has been associated with low RANTES expression and an anti-inflammatory status [5]. A 32 bp insertion/deletion polymorphism has been described in exon 3 of the CCR5 gene (CCR5D32, rs333) that abrogates functional CCR5 receptor expression, weakening the pro-inflammatory CCR5-mediated action [6]. The CCR5D32 allele reaches appreciable frequencies only in Europe, following a latitudinal cline distribution that is higher in the north and lower in the south. Studies have demonstrated that the CCR5D32 allele is related to reduction of portal inflammation during hepatitis C (HCV) infection, delayed progression in multiple sclerosis, protection against cardiovascular diseases (acute myocardial infarction and severe coronary heart disease), and attenuation of the inflammatory response that delays progression of atherosclerotic lesions.

The immune system's positive protective effect against pathogens and the spread of tumor cells can also become a detrimental chronic inflammation affecting longevity. Studies on the genetic component of longevity have tended to evaluate the role of immune system genes, especially those involved in inflammation. Results obtained reveal that persistent activation of inflammatory status is related to unsuccessful aging and that avoiding persistent inflammation contributes to healthy aging. However, a pro-inflammatory status is a common phenotype in older people [1]. 

To assess the possibility of a genetic component of inflammatory status in the elderly, we studied the distribution of functional polymorphic variants of two genes from the chemokine inflammatory pathway, RANTES and CCR5, in long-lived individuals.

Methods

We genotyped RANTES (cid:2)403G/A and Int1.1T/C and CGenotype and allele distributions between controls and the elderly were analyzed using contingency table analysis performed by the OpenEpi web resource (http://www.openepi.com/OE2.3/Menu/OpenEpiMenu.htm). Differences were evaluated for all subjects and by sex between cohorts. For comparisons including zero values, odds ratio and 95%CI were calculated based on the Peto odds ratio method using the online calculator http://www.hut-chon.net/ConfidORnulhypo.htm. This approach has the advantage of accepting zero results without generating infinity. P values <0.05 were considered statistically significant. In addition, we used a modified Bonferroni-corrected nominal threshold of P = 0.05/N, where N is the effective number of independent marker loci after consideration of linkage disequilibrium between markers. N was calculated using the SNP (single nucleotide polymorphism) spectral decomposition approach web-based program SNPSpD (http://gump.qimr.edu.au/general/daleN/SNPSpD/). This yields an experiment-wide significance threshold of 0.02 to keep Type I error rate at 5%.