CCR2 polymorphism in chronic renal failure patients requiring long-term hemodialysis

New mechanisms of CCR5-Δ32 carriers' advantage - Impact on progenitor cells and renal function

BACKGROUND

CCR5 is a chemokine receptor expressed by various populations including leukocytes, smooth muscle cells and endothelium. Δ32 polymorphism of CCR5 gene has been connected with, inter alia, cardiovascular disease development. The aim of our study was to evaluate impact of CCR5 variant on CD34+ and CD34+VEGFR2+ cells - populations involved in cardiovascular system homeostasis and regeneration.

METHODS AND RESULTS

We have examined 170 Polish subjects from Pomeranian region. The analysis concerned CCR5 polymorphism and flow cytometry evaluation of whole blood cells. Our results indicate that individuals with at least one CCR5-Δ32 allele are characterized by greater number of CD34+CXCR4+, CD34+VEGFR2+ and CD34+VEGFR2+c-Kit + cells than their wild type counterparts. This group also exhibits more beneficial values of renal function parameters.

CONCLUSION

Maintaining greater size of CD34+ and CD34+VEGFR2+ populations as well as proper kidney function may constitute mechanisms that connect chemokine receptor polymorphism with cardiovascular system health.

CCR2 contributes to the recruitment of monocytes and leads to kidney inflammation and fibrosis development

Chemokines are a large family of proteins that, once associated to its receptor on leukocytes, stimulate their movement and migration from blood to tissues. Once in the tissue, immune cells trigger inflammation that, when uncontrolled, leads to fibrosis development. Among the immune cells, macrophages take a special role in fibrosis formation, since macrophage depletion reflects less collagen deposition. The majority of tissue macrophages is derived from monocytes, especially monocytes expressing the chemokine receptor CCR2. Here, we investigated the role of infiltrating CCR2⁺ cells in the development of fibrosis, and specifically, the dynamic of infiltration of these cells into kidneys under chronic obstructive lesion. Using liposome-encapsulated clodronate, we observed that macrophage depletion culminated in less collagen deposition and reduced chemokines milieu that were released in the damaged kidney after obstructive nephropathy. We also obstructed the kidneys of CCL3^-/-, CCR2^-/-, CCR4^-/-, CCR5^-/-, and C57BL/6 mice and we found that among all animals, CCR2^-/- mice demonstrated the more robust protection, reflected by less inflammatory and Th17-related cytokines and less collagen formation. Next we evaluated the dynamic of CCR2^+/rfp cell infiltration and we observed that they adhere onto the vessels at early stages of disease, culminating in increased recruitment of CCR2^+/rfp cells at later stages. On the other hand, CCR2^rfp/rfp animals exhibited less fibrosis formation and reduced numbers of recruited cells at later stages. We have experimentally demonstrated that inflammatory CCR2⁺ cells that reach the injured kidney at initial stages after tissue damage are responsible for the fibrotic pattern observed at later time points in the context of UUO.

Associations of fractalkine receptor (CX3CR1) and CCR5 gene variants with hypertension, diabetes and atherosclerosis in chronic renal failure patients undergoing hemodialysis

PURPOSE

We aimed to investigate the associations of fractalkine receptor (CX3CR1) V249I, T280M and CCR5-59029 A/G gene polymorphisms in chronic renal failure (CRF) subjects undergoing hemodialysis and to evaluate possible associations of these polymorphisms with hypertension (HT), diabetes mellitus (DM) and atherosclerosis (AS).

METHODS

A total of 225 CRF subjects undergoing hemodialysis and 201 healthy controls were enrolled in the study. CRF subjects were divided into three major subgroups according to comorbidities including HT (n = 127), DM (n = 65) and AS (n = 33). Genotyping was done using polymerase chain reaction-restriction fragment length polymorphism method.

RESULTS

The II genotype and I allele frequencies of CX3CR1 V249I polymorphism were found significantly more frequent in CRF subjects, CRF subjects with DM and CRF subjects with AS compared with controls (p < 0.05 for all comparisons). G allele frequency of CCR5 polymorphism was found significantly more prevalent in CRF subjects with DM than that of controls. Further, GG genotype and G allele frequencies of CCR5 polymorphism were significantly more prevalent in CRF subjects with AS compared with controls (p < 0.05). We also explored these polymorphisms among CRF subjects with and without following comorbidities: HT, DM, AS. We found significant association between CRF subjects with HT and without HT in terms of genotype and allele frequencies of V249I polymorphism (p < 0.05). CX3CR1 T280M polymorphism was not found significantly different in none of the comparisons.

CONCLUSION

These data demonstrate possible associations between CX3CR1 V249I and CCR5-59029 A/G polymorphisms and/or HT, DM and AS in CRF subjects.

Genetic Factors Affecting Late-Onset Alzheimer's Disease Susceptibility

Alzheimer's disease is considered a progressive brain disease in the older population. Late-onset Alzheimer's disease (LOAD) as a multifactorial dementia has a polygenic inheritance. Age, environment, and lifestyle along with a growing number of genetic factors have been reported as risk factors for LOAD. Our aim was to present results of LOAD association studies that have been done in northwestern Iran, and we also explored possible interactions with apolipoprotein E (APOE) status. We re-evaluated the association of these markers in dominant, recessive, and additive models. In all, 160 LOAD and 163 healthy control subjects of Azeri Turkish ethnicity were studied. The Chi-square test with Yates' correction and Fisher's exact test were used for statistical analysis. A Bonferroni-corrected p value, based on the number of statistical tests, was considered significant. Our results confirmed that chemokine receptor type 2 (CCR2), estrogen receptor 1 (ESR1), toll-like receptor 2 (TLR2), tumor necrosis factor alpha (TNF α), APOE, bridging integrator 1 (BIN1), and phosphatidylinositol-binding clathrin assembly protein (PICALM) are LOAD susceptibility loci in Azeri Turk ancestry populations. Among them, variants of CCR2, ESR1, TNF α, and APOE revealed associations in three different genetic models. After adjusting for APOE, the association (both allelic and genotypic) with CCR2, BIN1, and ESRα (PvuII) was evident only among subjects without the APOE ε4, whereas the association with CCR5, without Bonferroni correction, was significant only among subjects carrying the APOE ε4 allele. This result is an evidence of a synergistic and antagonistic effect of APOE on variant associations with LOAD.

The protective effect of MCP-1 -2518 A>G promoter polymorphism in Turkish chronic renal failure patients requiring long-term hemodialysis

OBJECTIVE

Monocyte chemoattractant protein-1 (MCP-1) plays a major role in the pathogenesis and progression of different types of human renal disease. Therefore, in this study, we aimed to investigate the effect of MCP-1 gene -2518 A>G promoter polymorphism in chronic renal failure (CRF) patients requiring long-term hemodialysis.

METHODS

The study population consisted of 201 adult CRF patients requiring long-term hemodialysis and 194 healthy controls. The polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used for genotyping of MCP-1 -2518 A>G polymorphism in the CRF patients and healthy controls.

RESULTS

There were statistically significant differences in terms of genotypic (χ (2) = 12.69, p = 0.02) and allelic (χ (2) = 5.72, p = 0.02) frequencies of MCP-1 -2518 A>G between CRF patients and control subjects. According to our results, in the patient group MCP-1 -2518 AA genotype frequency was significantly higher than that of control group. On the other hand, heterozygous AG genotype frequency in the control group was significantly higher than that of the study group. Three different main disease subgroups of CRF (hypertension, diabetes mellitus, and atherosclerosis) patients were also evaluated, and significant associations were found between hypertension (genotype: χ (2) = 9.28, p = 0.01; allele: χ (2) = 6.00, p = 0.01), atherosclerosis (genotype: χ (2) = 5.37, p = 0.02; allele: χ (2) = 4.13, p = 0.04), and distributions of MCP-1 -2518 A>G genotypes and alleles. However, no significant association was found between diabetes mellitus and distributions of MCP-1 -2518 A>G genotype and allele frequencies (genotype: χ (2) = 2.37, p = 0.3; allele: χ (2) = 1.88, p = 0.17).

CONCLUSION

Current data show that MCP-1 -2518 AA genotype may cause susceptibility to CRF, while G allele may have a protective effect against development of CRF. In addition, MCP-1 -2518 AA genotype seems to associate with CRF originated from hypertension and atherosclerosis in our study population.

Bcıı--RFLP profiles for serum amiloid A1 and mutated MEFV gene prevalence in chronic renal failure patients requiring long-term hemodialysis

BACKGROUND AND AIM

There is an increased mortality risk in long-term hemodialysis patients of renal failure due to the chronic inflammation. The relationship between the chronic renal failure (CRF) and the role of familial genetic markers remains incompletely understood. In the current study, it was aimed to find out the prevalence of common MEFV gene mutations and BcII polymorphism in serum amyloid A1 (SAA1) gene in chronic renal patients (CRF) who require long-term hemodialysis.

METHOD

Current cohort includes 242 CRF patients and 245 healthy individuals from the same population. Total genomic DNA was isolated from peripheral blood-EDTA samples and genotyping of target MEFV gene was carried out by reverse hybridization Strip Assay and real-time techniques. The SAA1 gene was genotyped by the BclI-RFLP method.

RESULTS

Increased mutated MEFV genotypes were found in current CRF patients when compared with the control group from the same ethnicity and the difference was statistically significant (Table 2) (OR: 4.9401, 95% CI: 3.0694-7.9509), p<0.0001. The most frequent point mutations were M694V and E148Q. The mutated T allel frequency in the SAA1 gene was also different when compared with the healthy controls and the difference was found to be statistically significant (χ2: 13.18; p=0.000).

CONCLUSIONS

The current results indicate the germ-line mutations in both genetic biomarkers (MEFV and SAA1 genes) that are related to inflammation and amyloidosis processes may play a crucial role in CRF pathogenesis due to the long-term chronic inflammation.

Effects of the Chemokine Receptor 5 (CCR5)-Delta32 Mutation on Hepatitis C Virus-Specific Immune Responses and Liver Tissue Pathology in HCV Infected Patients

BACKGROUND

The specific antiviral T cells provide CC chemokine receptor 5 (CCR5) for the immune response during the hepatitis C virus (HCV) infection. Heterogenous and/or homozygous 32 base pair deletion in CCR5 gene (CCR5Δ32 bpdel) leads to reduced protein expression.

OBJECTIVES

In the current case control study, we aimed to compare the histopathological findings of liver to the CCR5Δ32 bpdel mutation profiles, expression and some other clinical findings in patients with chronic HCV infection.

MATERIALS AND METHODS

Multiple Strip Assay reverse hybridisation and Real Time PCR techniques were used to determine the germline CCR5 mutations and immunohistochemical technique was used to evaluate the gene expression in targer tissue biopsies.

RESULTS

Target CCR5 WT/WT, WT/Δ32, and Δ32/Δ32 genotypes were observed in 91.4%, 8.6% and 0.0% for HCV positive patients and 98.3%, 1.7% and 0.0% for control group respectively. The histologic activity index (HAI) was significantly lower (4.0 ± 1.0) in the mutated group than the non-mutated group (5.7 ± 1.0). Decreased fibrosis levels were detected in HCV positive mutated group.

CONCLUSIONS

Results showed that CCR5 polymorphism was more frequent in HCV positive patients than in healthy population in Turkish population. Current results also showed that mutated CCR5 signalling pathway due to CCR5-Delta32 may potentially result in subtle reduction of HCV specifity to the drug responses due to the positive impact on liver inflammation, fibrosis levels and liver destruction in HCV infection.

Investigation of chemokine receptor CCR2V64Il gene polymorphism and migraine without aura in the Iranian population

Background and Objectives. Migraine is a multifactorial common neurovascular disease with a polygenic inheritance. Inflammation plays an important part in migraine pathophysiology. C-C chemokine receptor 2 (CCR2) is an important chemokine for monocyte aggregation and transendothelial monocyte migration. The aim of our study was to investigate the association of migraine with CCR2V64Il polymorphism in the Iranian population. Methods. We assessed 103 patients with newly diagnosed migraine and 100 healthy subjects. Genomic DNA samples were extracted from peripheral blood and genotypes of CCR2V64Il gene polymorphism were determined. For measuring the severity of headache, every patient filled out the MIGSEV questionnaire. Results. There were no significant differences in the distribution of both 64Il allele and heterozygote (GA) genotype of CCR2 gene polymorphism (P = 0.396; OR = 0.92, 95% CI = 0.50–1.67 and P = 0.388; OR = 0.91, 95% CI = 0.47–1.73, resp.) between case and control groups. There was no significant difference of alleles frequency between three grades of MIGSEV (P = 0.922). Conclusions. In conclusion our results revealed no association between CCR2V64Il polymorphism and susceptibility to migraine and also headache severity in the Iranian population.