CCR5-Delta32 Mutation Research Articles

Short Communication:SDF1-3′A Gene Mutation Is Correlated with Increased Susceptibility to HIV Type 1 Infection by Sexual Transmission in Han Chinese

Limited information is available on host genetic polymorphisms that confer resistance to HIV-1 infection in Han Chinese who persistently remain seronegative (HEPS) despite high exposure to HIV-1 through unprotected sexual activity with known HIV-1-seropositive spouses or long-term sexual partners. The aim of this study was to investigate the correlation of CCR5-Delta32, CCR2b-64I, and SDF1-3'A polymorphisms with susceptibility to HIV-1 infection through sexual transmission in Han Chinese. A cross-sectional study was used to analyze the differences in allelic frequencies of CCR5-Delta32, CCR2b-64I, and SDF1-3'A among HEPS, healthy HIV-unexposed individuals, and HIV-1-seropositive individuals. Restriction fragment length polymorphism (RFLP) analysis was used for genotype determination. The CCR5-Delta32 mutation was not detected in the three groups (n = 260). The allelic frequencies of CCR2b-64I were 21.57%, 21.63%, and 22.12% in the three groups, respectively. There was no significant difference among the three groups in CCR2b-64I distribution. The allelic frequencies of SDF1-3'A were 20.19%, 28.37%, and 29.33% in the three groups, respectively. There was a significant difference in the allelic distribution of SDF1-3'A between HEPS and healthy HIV-unexposed individuals (p = 0.023), as well as between HEPS and HIV-1-seropositive individuals (p = 0.049). Statistical analysis showed that the allelic distributions on CCR2b-64I and SDF1-3'A were in equilibrium according to the Hardy-Weinberg equation. The mutant genotypes of CCR5-Delta32 and CCR2b-64I were not correlated with HIV-1 infection through sexual transmission in Han Chinese. SDF1- 3'A was associated with a high risk of HIV-1 infection through sexual transmission in Han Chinese.

Association of CCR5-delta32 Mutation with Reduced Risk of Nonatopic Asthma in Slovenian Children

Asthma is one of the most common chronic diseases of childhood. Asthma results from the interaction of several genes and environmental influences. Viral infections are common triggers of asthma attacks, especially in nonatopic asthmatics. CCR5 is a chemokine receptor involved in the immune response against a number of viruses. A 32 base pair deletion (delta32) in the CCR5 receptor gene causes loss of gene function and is associated with several chronic diseases due to the resulting altered immunity. The results of the association studies exploring the role of the CCR5 receptor gene in asthma pathogenesis are contradictory. We studied 111 children aged between 5 and 18 years with mild or moderate persistent asthma; 75 of them were atopic and 36 had nonatopic asthma. We carried out allergy and spirometry tests, a bronchoprovocation test with methacholine and performed measurement of exhaled nitric oxide and genotyping for CCR5-delta32 mutation. Compared with 365 nonatopic, nonasthmatic controls we found significantly lower CCR5-delta32 allelic frequency in nonatopic asthmatics (p = 0.016, OR 0.139, 95% CI 0.02 to 0.984) but not in atopic asthmatics. CCR5-delta32 mutation protects against nonatopic asthma. This association offers new insights into the pathogenesis of an important asthma phenotype and could serve as useful information for the future research of new asthma management strategies.

Lack of Higher Frequency of the Chemokine Receptor 5-??32/??32 Genotype in Hepatitis C

An elevated frequency of the CCR5-Delta32 mutation in German patients with hepatitis C with viremia has been reported. The aim of the present study was to verify whether this mutation occurs in an Italian population with hepatitis C and whether it is an adverse host factor indicative of severity of liver disease and response to antiviral therapy. The authors amplified 189-bp (wild-type) and 157-bp (Delta32 deletion) fragments of the CCR5 gene by polymerase chain reaction in 130 patients with chronic hepatitis C. Comparisons were drawn with 110 blood donors and 135 patients with primary biliary cirrhosis. Four (3.1%) patients with chronic hepatitis C and 1 blood donor (0.9%) were CCR5-Delta32 homozygous, whereas there was no CCR5-Delta32 homozygosity among primary biliary cirrhosis patients; the wild-type gene was present in a similar percentage in the 3 groups of patients without any significant difference (83.1% vs 90.4% vs 83.6%, respectively). Among the patients with chronic hepatitis C, no significant correlation was found between CCR5-Delta32 homozygosity and the following parameters: histologic grade/stage, hepatitis C virus genotype, viral load, serum aspartate aminotransferase, serum alanine aminotransferase, and serum gamma-glutamyltransferase. Ninety-five patients received a standard antiviral protocol with pegylated interferon (PEG Intron)+ribavirin; a sustained response was achieved in 59 patients (62.1%), and the remainder did not respond or experienced a relapse. Response to treatment was not influenced by CCR5-Delta32 deletion. No greater frequency of CCR5-Delta32 homozygosity was seen in an Italian population of patients with chronic hepatitis C. This mutation does not seem to influence either the overall severity of liver disease or the response to viral therapy.

CC-Type chemokine receptor 5-Δ32 mutation protects against primary sclerosing cholangitis

Primary sclerosing cholangitis (PSC) is commonly associated with inflammatory bowel disease (IBD) and characterized by fibrosing inflammatory destruction of biliary ducts. The pathogenesis of PSC remains unknown, but immunological, bacterial, viral, and toxic factors play a role in a genetically susceptible host. We hypothesized that CC-type chemokine receptor 5 (CCR5) would be an interesting candidate gene for susceptibility to PSC from its chromosomal location within the IBD susceptibility locus on 3p21, as well as from a functional perspective. We therefore investigated the role of the functional 32-bp deletion in this gene (CCR5-Delta32) with regard to susceptibility to PSC. A total of 110 patients with PSC, 56 with concomitant IBD (23 with Crohn's disease, 28 with ulcerative colitis, 5 with indeterminate colitis), were collected. All of the subjects were genotyped for CCR5-Delta32 with polymerase chain reaction amplification, followed by detection on ethidium bromide-stained agarose gel. Genotypes and allele frequencies were compared with a cohort of IBD patients without PSC (n = 400) and healthy control subjects (n = 362). The frequency of the CCR5-Delta32 mutation in PSC (6.8%) was significantly lower compared with IBD (12.6%; P = 0.016) and healthy control subjects (12.2%, P = 0.026), suggesting a protective effect of this mutation on PSC. None of the PSC patients with severe disease necessitating liver transplantation (n = 17) carried CCR5-Delta32. Because an intact CCR5 receptor is needed for internalization of specific pathogens and homing of memory T lymphocytes to the liver, we hypothesize that a deficient expression of this receptor resulting from the CCR5-Delta32 variant may protect against PSC.

CCR5Δ32 mutation does not influence the susceptibility to HCV infection, severity of liver disease and response to therapy in patients with chronic hepatitis C

To study whether CCR5Delta32 mutation was associated with viral infection and severity of liver disease. Two hundred and fifty two histologically proven, chronic HCV patients (mean age: 41 +/- 14 years; M/F: 164/88) were genotyped. PCR based genotyping of 32 bp deletion at the CCR5 locus was done. Four-hundred and eight matched healthy controls were studied to assess susceptibility to HCV infection. To assess correlation of immune gene polymorphism with severity of HCV related liver disease, patients with chronic HCV infection were divided into those with a fibrosis score of <= 2 (mild) or > 2 (severe) and histological activity index (HAI) of <= 5 or > 5. For correlation between CCR5Delta32 mutations and response to therapy, 129 patients who completed therapy were evaluated. The majority (89.4%) of the patients were infected with genotype 3. The frequency of homozygous CCR5Delta32 mutants was comparable to HCV patients as compared to the healthy controls (0.7% vs 0%, P = 0.1). Further more, the frequency of CCR5Delta32 mutation was comparable in patients with mild or severe liver disease. (P = NS). There was also no association observed with response to therapy and CCR5Delta32 mutation. CCR5Delta32 mutation does not have a role in disease susceptibility, severity or response to therapy in patients with chronic hepatitis C infection.

Frequency of the CCR5-Δ32 Mutation in the Atlantic Island Populations of Madeira, the Azores, Cabo Verde, and São Tomé e Príncipe

There is evidence that the CCR5-delta32 mutation confers protection against HIV-1 infection to homozygous individuals. It is believed that this mutation spread through Europe with the Vikings and that it has been subjected to positive selection, leading to a high frequency in Europe (approximately 10%). We carried out the present study to determine the 32-bp deletion allele and genotype frequencies of the CCR5 gene (CCR5-delta32) in the Atlantic island populations of Madeira, the Azores, Cabo Verde, and São Tomé e Principe. These Atlantic archipelagos were all colonized by the Portuguese in the 15th and 16th centuries, but the latter two received most of their settlers from the West African coast. The frequency of the CCR5-delta32 mutation varies between 0% in São Tomé e Príncipe and 16.5% in the Azores. The Azores Islands have one of the highest frequencies of homozygotes found in Europe (4.8%). There are significant differences (P < 0.05) between some of these populations, for example, between São Tomé e Príncipe and Cabo Verde, and even within populations (e.g., Portugal, Madeira, and the Azores).

Distribution of the mutated Δ32 allele of the CCR5 gene in a Sicilian population

The CCR5 gene encodes a cell-surface chemokine receptor molecule that serves as a co-receptor for macrophage-tropic strains of human immunodeficiency virus type 1 (HIV-1). A mutation in this gene may alter the expression or the function of the protein product, thereby altering chemokine binding and/or signalling or HIV-1 infection of cells that normally express CCR5 protein. Individuals homozygous for a 32-bp deletion allele of CCR5 (CCR5 delta32), heritable as a Mendelian trait, are relatively resistant to HIV-1 infection. The CCR5 delta32 mutation is present in the Caucasian population at different frequencies. The aim of this study was to investigate the frequency of truncated alleles of the CCR5 delta32 gene in a Sicilian population, as the interpopulation variation in CCR5 delta32 frequency may be a significant factor in the prediction of AIDS endemicity in future studies. We examined 901 healthy individuals from several Sicilian provinces. We found a mean (+/- standard deviation) delta32 allele frequency (fr) of 0.04 +/- 0.012. The highest value was observed in the province of Messina, with a mean delta32 allele frequency of 0.06 +/- 0.024, where we collected samples from a cohort of 114 HIV-1-infected individuals. The observed frequency amongst these patients was quite low (fr = 0.03 +/- 0.031) compared to the healthy population, although the difference was not statistically significant.

Chemokine receptor 5 and primary biliary cirrhosis: a two‐centre genetic association study

Chemokines and their receptors are important mediators of leucocyte trafficking and are suggested to be critical for establishment of inflammatory autoimmune processes. CC chemokine receptor 5 (CCR5) is expressed preferentially by CD4+ T cells. We hypothesised that the CCR5delta(Delta)32 genotype, which impairs surface expression of CCR5 in heterozygotes and is linked to a functional polymorphism of CD45RA expressed on suppressor-inducer-like 'naive' CD4+ T cells, may modulate the inflammatory process in primary biliary cirrhosis (PBC). CCR5Delta32 polymorphism was determined by PCR in 226 Caucasian PBC patients and 197 racially matched controls from two geographical areas, Newcastle, UK and Padua, Italy. (UK: 144 PBC, 105 controls, Italy: 82 PBC, 92 controls). When the two series were analysed separately, there were no significant differences in the genotype distribution comparing patients and controls (UK: wt/wt 72% vs 76%; wt/Delta32 28% vs 22%; Delta32/Delta32 0% vs 2%, P=0.24; Italy: wt/wt 72% vs 82%; wt/Delta32 27% vs 17%; Delta32/Delta32 0% vs 1%, P=0.14). However, when the data for the two series were pooled and reanalysed, we found an increase in the CCR5Delta32 mutation in PBC patients vs controls (28% vs 21%, OR=1.43, P=0.03), but there was no evidence that this Delta32 polymorphism is associated with less severe disease. Although this two-centre genetic association study is large compared with others performed in PBC, taken separately, each geographically based cohort of patients and controls is underpowered to detect a small effect of this functional polymorphism. This emphasises the need for far larger case-control collections to address which polymorphic markers or haplotypes might modify the pathogenesis and clinical course of PBC. We propose that multi-centre collaboration on an international scale in 'orphan' complex liver diseases such as (PBC) is supported by the International Association for the Study of the Liver and promoted via their journal with development of a brief format for web-based publication of studies.

CC-chemokine receptor 5 (CCR5) in hepatitis C--at the crossroads of the antiviral immune response?

An effective immune response to hepatitis C virus (HCV) infection requires efficient recruitment and activation of inflammatory cells to the liver, the site of infection. Chemokines are critically involved in this process, since they exert both chemotactic and immunoregulatory actions. In particular, the interaction between chemokines CCL3 (MIP-1alpha), CCL4 (MIP-1beta) and CCL5 (RANTES) and their receptor, CC-chemokine receptor 5 (CCR5), may be critical in regulating T cell functions by mediating recruitment, polarization, activation and differentiation of antiviral type 1 cytokine secreting T helper and cytotoxic T cells. A 32 bp deletion in the encoding region of CCR5 leads to complete loss of the functional CCR5 receptor in subjects homozygous for this mutation and decreased expression in heterozygous patients. This fact provides the unique opportunity to study the role of the CCR5 receptor in chronic hepatitis C infection by comparing immune responses between HCV infected CCR5-Delta32 carriers and CCR5 wild-type patients. This article will summarize and discuss the available data with respect to possibly altered disease susceptibility, clinical course and treatment outcomes associated with the CCR5-Delta32 mutation in hepatitis C.

Evidence for Gag p24-specific CD4 T cells with reduced susceptibility to R5 HIV-1 infection in a UK cohort of HIV-exposed-seronegative subjects.

To characterize HIV-1 Gag p24-specific CD4 cell responses in HIV-exposed-seronegative (ES) individuals. Twelve ES individuals, of diverse ethnicity and wild type for the CCR5 Delta-32 mutation, were identified. Controls were HIV-negative blood donors. Gag p24-specific and total Vbeta+ CD4 cells that expressed MIP-1beta, IFN-gamma and IL-2 were enumerated by intracytoplasmic cytokine staining. beta-Chemokine expression was correlated with susceptibility to R5 HIV-1 infection, as measured by polymerase chain reaction for integrated HIV-1 and by p24 enzyme-linked immunosorbent assay. Similar numbers of mitogen-stimulated and Vbeta+ MIP-1beta+, IFN-gamma+ and IL-2+ T cells were found in ES and HIV-negative control subjects. However, all ES subjects tested had an HIV Gag p24-specific MIP-1beta+, IFN-gamma+ and IL-2+ CD4 T-cell response that was rare in controls. p24-Specific cells of all ES but no control subjects could be expanded by in-vitro Ag/IL-2 stimulation, and when re-stimulated with an overlapping peptide series showed evidence of a broad CD4 cell memory response directed against multiple regions of Gag p24. Mitogen-stimulated ES CD4 cells were as susceptible to HIV infection as those from control subjects, but p24-specific IFN-gamma+ CD4 cells of six out of seven ES subjects tested were less susceptible to R5 HIV-1 infection than the counterpart fraction depleted of p24-specific IFN-gamma+ cells. The addition of blocking anti-beta-chemokine antibodies did not promote R5 HIV-1 infection of p24-specific IFN-gamma+ cells. Specific CD4 cell immunity, characterized by a broadly directed memory Gag-p24 CD4 cell response and reduced susceptibility of specific CD4 cells to R5 HIV-1 infection, is a likely correlate of non-transmission.

Prevalence of the CCR5Delta32 mutation in Brazilian populations and cell susceptibility to HIV-1 infection.

We investigated the occurrence of the CCR5Delta32 mutation in various regional ethnic groups in Brazil and tested the resistance of mutant peripheral blood mononuclear cells (PBMCs) to infection by HIV-1 in vitro. The heterozygous prevalence was 5.3% in uninfected African descendents and 8.8% in HIV-1-positive individuals (neither population had Delta32/Delta32). German descendents were 11% heterozygous and l% Delta32/Delta32. Amerindians were exclusively CCR5/CCR5. Heterozygous uninfected PBMCs showed partial resistance to R5-HIV-1 strains in vitro, but no resistance to X4 virus. HIV-1-positive CCR5/CCR5 had higher viral loads than did heterozygous cells.

Heterozygosity for CCR5-Delta32 but not CCR2b-64I protects against certain intracellular pathogens.

To determine the association between CCR5 and CCR2b genotype and the clinical manifestation of first and subsequent AIDS-defining illnesses (ADIs). The distribution of ADIs was examined by CCR5 and CCR2b genotype in a subset of homosexual men enrolled in the Sydney AIDS Prospective Study. The expected number of ADIs was calculated from rates observed in the same tertiary hospital over the same period. Information on initial ADI was collected for 117 homosexual men diagnosed with AIDS before January 1998. Of these individuals, 17 were heterozygous for the CCR5-Delta32 mutation and 11 were heterozygous for CCR2b-64I. The number of observed cases of Pneumocystis carinii pneumonia (PCP), toxoplasmosis, Mycobacterium avium complex (MAC) and cryptosporidiosis reported as a first ADI was substantially fewer in people heterozygous for the CCR5-Delta32 mutation than for those without the mutation, despite similar age, CD4 T-cell count at AIDS diagnosis, year of AIDS diagnosis and receipt of antiretroviral treatment. In addition, among individuals heterozygous for CCR5-Delta32 there were fewer cases of PCP, toxoplasmosis, MAC, and cryptosporidiosis observed as subsequent ADIs compared to the number expected, based on rates measured in the same hospital during the same period (seven observed vs. 24 expected, RR = 0.3, 95% CI = 0.01-0.6). The distribution of first and subsequent ADIs did not differ from the number expected in individuals heterozygous for the CCR2b-64I mutation. Results from this study show that heterozygosity for CCR5-Delta32 but not CCR2b-64I appears to protect against opportunistic infections.

Frequency analysis of the CCR5delta32 mutation in patients with brucellosis.

This study investigated the influence of the host's CCR5 genotype in human brucellosis. Genotype analysis for the CCR5delta32 mutation was performed in 185 brucellosis patients and 141 healthy volunteers, all recruited in northern Greece. In the brucellosis-infected patients the CCR5delta32 genotype distribution showed a significant deviation from the Hardy-Weinberg equilibrium (p = 0.030), owing to the presence of 2 individuals homozygous for delta32 among the 185 brucellosis patients compared with none of the 141 controls. Extended studies should be performed to confirm an association between CCR5 genotype and the risk of acquiring brucellosis.

CCR5Delta32 and promoter polymorphisms are not correlated with initial virological or immunological treatment response.

Natural genetic polymorphisms within the CCR5 gene and promoter have been linked to patterns of HIV-1 clinical disease progression in untreated individuals. The objective of this retrospective study was to assess the influence of the CCR5Delta32 mutation and promoter polymorphisms on virological and immunological treatment outcome in 436 antiretroviral-naive individuals initiating their first therapy, over a mean follow-up time of 22 months. Genotypes for the CCR5Delta32 and promoter were determined by polymerase chain reaction amplification of human DNA from plasma, followed by gel electrophoresis for CCR5Delta32 or DNA sequencing for the promoter polymorphisms. Time to virological failure [defined as the second plasma viral load > or = 400 copies HIV-1 RNA/ml) and immunological failure (defined as time to achieve two successive CD4 cell counts below baseline) were analyzed by Kaplan-Meier methods. The five most common CCR5 promoter polymorphisms were observed at positions 208(G/T), 303(A/G), 627(C/T), 676(A/G), and 927(C/T). Allele frequencies were 0.24(208T), 0.38(303G), 0.44(627T), 0.35(676G) and 0.18(927T). The CCR5Delta32 allele frequency was 0.08. The promoter polymorphisms existed in strong linkage disequilibrium with each other and the Delta32. No significant effect of the individual CCR5Delta32 or promoter polymorphisms could be demonstrated with respect to time to treatment failure as defined by virological or immunological parameters (P > or = 0.07). Similarly, when combined CCR5Delta32 and promoter genotypes were analyzed in order to account for linkage disequilibrium, no significant effect was observed on time to virological or immunological failure (P > 0.6). CCR5Delta32 and promoter genotypes may not be of clinical relevance in predicting initial virological or immunological response to antiretroviral therapy.

Adverse effect of the CCR5 promoter −2459A allele on HIV‐1 disease progression

HIV positive individuals heterozygous for a 32 basepair deletion in the CCR5 encoding gene (CCR5 Delta32) have a reduced number of CCR5 receptors on the cell surface and a slower progression towards AIDS and death. Other human polymorphisms, such as the CCR2 64I and the CCR5 promoter -2459 A/G transition that has been discovered recently, have also been shown to influence HIV progression. Since genetic linkages make these polymorphisms interdependent variables, the aim of the present study was to isolate and evaluate the effect on HIV disease progression for each of these mutations independently. Genotypes were determined in 119 individuals enrolled in the Copenhagen AIDS Cohort. When including the concurrent effects of the CCR5 Delta32 and CCR2 64I mutations, homozygous carriers of the CCR5 promoter -2459A allele had a significantly faster progression towards death than heterozygous A/G individuals (P = 0.03), whereas this adverse effect was not significant when comparing A/A and G/G individuals. However, independent analysis revealed a significant adverse effect of the CCR5 promoter -2459A allele. Homozygous carriers of the -2459A allele that lack the protective effects of the CCR5 Delta32 and CCR2 64I mutations were found to have a median survival of 6.0 years, whereas carriers of the -2459G allele had a median survival of 9.4 years (P < 0.01).

Analysis of the CC chemokine receptor 5 (CCR5) delta-32 polymorphism in inflammatory bowel disease.

The inflammatory bowel diseases (IBD) Crohn's disease (CD) and ulcerative colitis (UC) are complex multifactorial traits involving both environmental and genetic factors. Recent studies have shown the important role of pro-inflammatory cytokines and chemokines, including RANTES, in IBD. RANTES is the natural ligand for the CC-chemokine receptor 5 (CCR5). The chromosomal location of the CCR5 gene on 3p21 coincides with an IBD-susceptibility locus identified by genome-wide scanning. A 32-bp deletion (A32) in the CCR5 gene results in a nonfunctional receptor and is found with high frequency in Caucasians. In this study, we investigated the presence of the CCR5delta32 allele in a large cohort of IBD patients and in a healthy control population. Blood samples were obtained from 538 unselected IBD cases (433 unrelated IBD patients: 289 CD, 142 UC, 2 indeterminate colitis; 105 affected first-degree relatives) and 135 unaffected first-degree family members. Of the IBD patients, 36% had familial IBD with at least two members being affected. There were no significant differences in the CCR5delta32 mutation frequency between IBD patients and healthy controls, nor between CD and UC patients. There was no correlation between the CCR5delta32 genotype and the age at IBD-diagnosis, the frequency of surgical intervention, or disease localization. Only the association between CCR5delta32 homozygosity and the presence of anal lesions in CD patients was statistically significant (P=0.007). Analysis by the transmission/disequilibrium test showed no significant transmission distortion to the probands or their clinically silent siblings. Based on these results, it is unlikely that the CCR5delta32 allele is an important marker for predisposition to IBD.

Frequency of CCR5 delta-32 mutation in human immunodeficiency virus (HIV)-seropositive and HIV-exposed seronegative individuals and in general population of Medellin, Colombia.

Repeated exposure to human immunodeficiency virus (HIV) does not always result in seroconversion. Modifications in coreceptors for HIV entrance to target cells are one of the factors that block the infection. We studied the frequency of Delta-32 mutation in ccr5 gene in Medellin, Colombia. Two hundred and eighteen individuals distributed in three different groups were analyzed for Delta-32 mutation in ccr5 gene by polymerase chain reaction (PCR): 29 HIV seropositive (SP), 39 exposed seronegative (ESN) and 150 individuals as a general population sample (GPS). The frequency of the Delta-32 mutant allele was 3.8% for ESN, 2.7% for GPS and 1.7% for SP. Only one homozygous mutant genotype (Delta-32/Delta-32) was found among the ESN (2.6%). The heterozygous genotype (ccr5/Delta-32) was found in eight GPS (5.3%), in one SP (3.4%) and in one ESN (2.6%). The differences in the allelic and genotypic frequencies among the three groups were not statistically significant. A comparison between the expected and the observed genotypic frequencies showed that these frequencies were significantly different for the ESN group, which indirectly suggests a protective effect of the mutant genotype (Delta-32/Delta-32). Since this mutant genotype explained the resistance of infection in only one of our ESN persons, different mechanisms of protection must be playing a more important role in this population.