CCR5 gene polymorphism is a genetic risk factor for radiographic severity of rheumatoid arthritis

Chemokines and chemokine receptors as promising targets in rheumatoid arthritis

Rheumatoid arthritis (RA) is an autoimmune disease that commonly causes inflammation and bone destruction in multiple joints. Inflammatory cytokines, such as IL-6 and TNF-α, play important roles in RA development and pathogenesis. Biological therapies targeting these cytokines have revolutionized RA therapy. However, approximately 50% of the patients are non-responders to these therapies. Therefore, there is an ongoing need to identify new therapeutic targets and therapies for patients with RA. In this review, we focus on the pathogenic roles of chemokines and their G-protein-coupled receptors (GPCRs) in RA. Inflamed tissues in RA, such as the synovium, highly express various chemokines to promote leukocyte migration, tightly controlled by chemokine ligand-receptor interactions. Because the inhibition of these signaling pathways results in inflammatory response regulation, chemokines and their receptors could be promising targets for RA therapy. The blockade of various chemokines and/or their receptors has yielded prospective results in preclinical trials using animal models of inflammatory arthritis. However, some of these strategies have failed in clinical trials. Nonetheless, some blockades showed promising results in early-phase clinical trials, suggesting that chemokine ligand-receptor interactions remain a promising therapeutic target for RA and other autoimmune diseases.

A Polymorphism in C-C Chemokine Receptor 5 (CCR5) Associates with Löfgren's Syndrome and Alters Receptor Expression as well as Functional Response

C-C chemokine receptor 5 (CCR5) and polymorphisms in CCR5 gene are associated with sarcoidosis and Löfgren's syndrome. Löfgren's syndrome is an acute and usually self-remitting phenotype of sarcoidosis. We investigated whether the single nucleotide polymorphism (SNP) rs1799987 is associated with susceptibility for Löfgren's syndrome and has an effect on CCR5 expression on monocytes and function of CCR5. A total of 106 patients with Löfgren's syndrome and 257 controls were genotyped for rs1799987. Expression of CCR5 on monocytes was measured by flowcytometry. We evaluated calcium influx kinetics following stimulation upon N-formylmethionyl-leucyl-phenylalanine (fMLP) and macrophage inflammatory protein-1α (MIP-1α) on monocytes by measuring the median fluorescence intensity (MFI). The frequency of the G allele of rs1799987 was significantly higher in Löfgren's syndrome than in healthy controls (p = 0.0015, confidence interval (CI) 1.22-2.32, odds ratio (OR) 1.680). Patients with a GG genotype showed higher CCR5 expression on monocytes than patients with the AA genotype (p = 0.026). A significantly (p = 0.027) lower count of patients with the GG genotype showed a calcium influx reaction to simulation upon MIP-1 α, compared with patients with the AA genotype. The rs1799987 G allele in CCR5 gene is associated with susceptibility to Löfgren's syndrome and with quantitative and qualitative changes in CCR5, potentially effecting the inflammatory response.

Comparison of rheumatoid arthritis (RA) and osteoarthritis (OA) based on microarray profiles of human joint fibroblast-like synoviocytes

The purpose of the present study was to investigate the underlying molecular mechanism of osteoarthritis (OA) and rheumatoid arthritis (RA) based on microarray profiles. Three human joint fibroblast-like synoviocytes (FLSs) microarray profiles including 26 OA samples, 33 RA samples, and 20 healthy control (HC) samples were downloaded from the GEO database. Differentially expressed genes (DEGs) between OA and HC (DEGsOA) and RA and HC (DEGsRA) were identified. Co-expressed and specific genes were analysed between DEGsOA and DEGsRA. Gene ontology, KEGG pathway enrichment, PPI network, and GSEA were performed to predict the function of DEGs. Two hundred seventy-six and 410 differential genes in DEGsOA and DEGsRA were observed. One hundred fifty coexpressed genes and 126 OA-specific genes (SELE, SERPINE1, and NFKBIA were the key genes) between DEGsOA and DEGsRA were enriched in the tumour necrosis factor (TNF) signalling pathway. However, 260 RA-specific genes of which the key genes were CCR5, CCR7, CXCR4, CCL5, and CCR4 were enriched in chemokine signalling pathway. Therefore, FLSs might exert an inflammatory effect by regulating TNF signalling pathway, targeting SELE, SERPINE1, and NFKBIA during the process of OA. Although TNF signalling pathway was also involved in the synovitis of RA, chemokine signalling pathway played the key role in RA FLSs mediating cell migration, invasion, and release of chemotaxis. In addition, CCR5, CCR7, CXCR4, CCL5, and CCR4 might be hub genes in RA. The different biomarkers and pathways identified in OA and RA may provide references for further study. SIGNIFICANCE OF THE STUDY: This study revealed the similar and different mechanisms of FLSs and different biomarkers that might with important regulatory effects on RA and OA. In OA, FLSs played an inflammatory role through TNF signalling pathway, targeting SELE, SERPINE1, and NFKBIA. Although TNF signalling pathway was also involved in the synovitis of RA, chemokine signalling pathway was a crucial pathway in mediating FLSs migration, invasion, and release of chemotaxis. CCR5, CCR7, CXCR4, CCL5, and CCR4 might be keys genes in RA. We expect that our results will bring more comprehensively understanding between RA and OA for researchers.

Genetic variants in chemokine CC subfamily genes influence hepatitis C virus viral clearance

Chemokine genes may influence both hepatitis C virus (HCV) spontaneous clearance in acute infection and treatment response in chronic infection. We conducted this study to evaluate whether the genetic variants in several CC family genes influence HCV spontaneous clearance and treatment response. The current research genotyped eight SNPs, including CCR1 rs3733096, rs13096371, CCR5 rs746492, rs1800874, CCL3 rs1130371, CCL5 rs3817656, CCL8 rs1133763, CCL14 rs854625, to explore their associations with HCV spontaneous clearance and response to treatment in two populations. We identified that the CCR1 rs3733096 (dominant model: adjusted OR = 2.29, 95% CI = 1.49-3.53, additive model: adjusted OR = 2.21, 95% CI = 1.50-3.25) and CCL5 rs3817656 (dominant model: OR = 1.37, 95% CI = 1.10-1.70, additive model: OR = 1.33, 95% CI = 1.12-1.58) were associated with HCV spontaneous clearance in Chinese Han population, while we found no association with treatment response. Moreover, the expression quantitative trait loci (eQTL) analysis showed that the risk alleles of rs3817656 were significantly associated with downregulated expression of CCL5 in whole blood (P < 0.001). The polymorphism of CCR1 rs3733096 and CCL5 rs3817656 are associated with spontaneous clearance of HCV in Chinese Han population.

Effects of lentivirus-mediated ornithine decarboxylase gene on the proliferation and apoptosis of fibroblast-like synoviocytes in rats with arthritis

OBJECTIVE

This study aimed to explore the effects of lentivirus-mediated ornithine decarboxylase (ODC) gene on the proliferation and apoptosis of fibroblast-like synoviocytes (FLSs) in rats with rheumatoid arthritis (RA).

METHODS

Twenty Lewis rats were randomized into control group (ten rats without processing) and RA group (ten rats of adjuvant-induced arthritis). The third-generation FLSs were randomized into test, control and blank groups. MTT assay and flow cytometry were employed to detect cell proliferation and apoptosis, respectively. Enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of tumor necrosis factor α (TNF-α), interferon-γ (IFN-γ), and interleukin-2 (IL-2).

RESULTS

Lewis rats in the RA group became ill from 11days on and got seriously ill 18days after modeling. However, rats in the control group had no obvious change. MTT assay showed that the test group had higher cell proliferation than the blank and control groups (P₁<0.001; P₂<0.001). Flow cytometry revealed that the apoptosis of FLSs in the test group was significantly lower than that in the blank and control groups (P₁<0.001; P₂<0.001). ELISA showed that the test group had higher TNF-α, IFN-γ and IL-2 level than the control and blank groups (all P<0.001), but no significant difference was found between the control and blank groups (all P>0.05).

CONCLUSION

The results indicated that overexpression of ODC gene promotes the proliferation while suppressing apoptosis of FLSs in rats with RA.

CCL5 rs2107538 Polymorphism Increased the Risk of Tuberculosis in a Sample of Iranian Population

Cysteine-cysteine chemokine ligand 5 (CCL5) with immunoregulatory and inflammatory activities has an important role in granuloma formations that activates and stimulates T-cells and macrophages. Cysteine-cysteine chemokine receptor 5 (CCR5) is a chemokine receptor, which is important for migration of immune cells to site of infection. In the present study we investigated the possible association between CCL5 -403G/A (rs2107538), CCL5 -28C/G (rs2280788) and CCR5 Δ32 polymorphisms and pulmonary tuberculosis (PTB) in an Iranian population. This case-control study was performed on 160 patients with pulmonary tuberculosis and 160 unrelated healthy subjects. The CCL5 -403G/A, CCL5 -28C/G and CCR5 Δ32 polymorphisms were genotyped by allele-specific polymerase chain reaction (AS-PCR), tetra amplification refractory mutation system polymerase chain reaction (T-ARMS PCR) and PCR, respectively. Our results showed that GA as well as GA+AA genotypes of CCL5 -403G/A (rs2107538) increased the risk of PTB in comparison with GG genotype (OR=1.70, 95% CI=1.03-2.81, P=0.038 and OR=1.64, 95% CI=1.00-2.68, P=0.049, respectively). No significant association was found between CCL5 -28C/G as well as CCR5 Δ32 polymorphism and PTB risk. In conclusion, our findings proposed that CCL5 -403G&gt;A polymorphism may be a risk factor for susceptibility to PTB in our population. Larger sample sizes with different ethnicities are required to validate our findings.

Genetics of rheumatoid arthritis susceptibility, severity, and treatment response

A decade after the first genome-wide association study in rheumatoid arthritis (RA), a plethora of genetic association studies have been published on RA and its clinical or serological subtypes. We review the major milestones in the study of the genetic architecture of RA susceptibility, severity, and response to treatment. We set the scientific context necessary for non-geneticists to understand the potential clinical applications of human genetics and its significance for a stratified approach to the management of RA in the future.

Genetic Variants Influencing Joint Damage in Mexican Americans and European Americans With Rheumatoid Arthritis

Joint destruction in rheumatoid arthritis (RA) is heritable, but knowledge on specific genetic determinants of joint damage in RA is limited. We have used the Immunochip array to examine whether genetic variants influence variation in joint damage in a cohort of Mexican Americans (MA) and European Americans (EA) with RA. We studied 720 MA and 424 EA patients with RA. Joint damage was quantified using a radiograph of both hands and wrists, scored using Sharp's technique. We conducted association analyses with the transformed Sharp score and the Immunochip single nucleotide polymorphism (SNP) data using PLINK. In MAs, 15 SNPs from chromosomes 1, 5, 9, 17 and 22 associated with joint damage yielded strong p-values (p < 1 × 10(-4) ). The strongest association with joint damage was observed with rs7216796, an intronic SNP located in the MAP3K14 gene, on chromosome 17 (β ± SE = -0.25 ± 0.05, p = 6.23 × 10(-6) ). In EAs, 28 SNPs from chromosomes 1, 4, 6, 9, and 21 showed associations with joint damage (p-value < 1 × 10(-4) ). The best association was observed on chromosome 9 with rs59902911 (β ± SE = 0.86 ± 0.17, p = 1.01 × 10(-6) ), a synonymous SNP within the CARD9 gene. We also observed suggestive evidence for some loci influencing joint damage in MAs and EAs. We identified two novel independent loci (MAP3K14 and CARD9) strongly associated with joint damage in MAs and EAs and a few shared loci showing suggestive evidence for association.

Chemokine Signaling Pathway Involved in CCL2 Expression in Patients with Rheumatoid Arthritis

PURPOSE

Rheumatoid arthritis (RA) is an inflammatory joint disorder, the progression of which leads to the destruction of cartilage and bone. Chemokines are involved in RA pathogenesis. In this study, we investigated the chemokine signaling pathway associated with CCL2 in peripheral blood (PB) and synovial tissues (ST) of RA patients based on our previous work about chemokine signaling pathway involved in the activation of CCL2 production in collagen-induced arthritis rat ST.

MATERIALS AND METHODS

Total RNA was isolated from PB leukocytes and synovium of the knee joint in both RA patients and control populations. Real-time polymerase chain reaction was used to determine CCL4, CCR5, c-Jun, c-Fos, and CCL2 expressions. Serum level of CCL2 was assessed by enzyme-linked immunosorbent assay, and the production of CCL2 in ST was analyzed immunohistochemically.

RESULTS

The expressions of CCL4, CCR5, c-Jun, c-Fos, and CCL2 messenger RNA in RA patients were significantly higher than those in healthy controls, both in ST and on PB leukocyte. Serum CCL2 levels were elevated in RA patients. Histological examination of rheumatoid joints revealed extensive CCL2 expression in RA ST.

CONCLUSION

CCL2, CCL4, c-Jun, c-Fos, and CCR5 may play an important role in the recruitment of PB leukocytes into the RA joints. These data provide evidence that the chemokine signaling pathway is involved in CCL2 expression in RA patient tissues, which may contribute to chronic inflammation associated with RA. Targeting this signaling pathway may provide a novel therapeutic avenue in RA.

Frequency of CCR5Δ32 allele in healthy Bosniak population

Recent evidence has demonstrated the role of CCR5Δ32 in a variety of human diseases: from infectious and inflammatory diseases to cancer. Several studies have confirmed that genetic variants in chemokine receptor CCR5 gene are correlated with susceptibility and resistance to HIV infection. A 32-nucleotide deletion within the CCR5 reading frame is associated with decreased susceptibility to HIV acquisition and a slower progression to AIDS. Mean frequency of CCR5Δ32 allele in Europe is approximately 10%. The highest allele frequency is observed among Nordic populations (about 12%) and lower in the regions of Southeast Mediterranean (about 5%). Although the frequency of CCR5Δ32 was determined in numerous European populations, there is a lack of studies on this variant in the Bosnia and Hercegovina population. Therefore, the aim of our study was to assess the frequency of CCR5Δ32 allele in the cohort of Bosniaks and compare the results with European reports. CCR5Δ32 was detected by sequence-specific PCR in a sample of 100 healthy subjects from Bosnia and Herzegovina (DNA collected 2011-2013). Mean age of the cohort being 58.8 (± 10.7) years, with 82% of women. We identified 17 heterozygotes and one mutant homozygote in study group, with mean ∆32 allele frequency of 9.5%. CCR5∆32 allele frequency among Bosniaks is comparable to that found in Caucasian populations and follows the pattern of the north-southern gradient observed for Europe. Further studies on larger cohorts with adequate female-to-male ratio are necessary.