The chemokine receptor 5 Delta32 mutation is associated with increased renal survival in patients with IgA nephropathy

CC chemokine receptor 5: the interface of host immunity and cancer

Solid tumors are embedded in a stromal microenvironment consisting of immune cells, such as macrophages and lymphocytes, as well as nonimmune cells, such as endothelial cells and fibroblasts. Chemokines are a type of small secreted chemotactic cytokine and together with their receptors play key roles in the immune defense. Critically, they regulate cancer cellular migration and also contribute to their proliferation and survival. The CCR5 chemokine receptor is involved in leucocytes chemotaxis to sites of inflammation and plays an important role in the macrophages, T cells, and monocytes recruitment. Additionally, CCR5 may have an indirect effect on cancer progression by controlling the antitumor immune response, since it has been demonstrated that its expression could promote tumor growth and contribute to tumor metastasis, in different types of malignant tumors. Furthermore, it was demonstrated that a CCR5 antagonist may inhibit tumor growth, consisting of a possible therapeutic target. In this context, the present review focuses on the establishment of CCR5 within the interface of host immunity, tumor microenvironment, and its potential as a targeting to immunotherapy.

Concordance of CCR5 genotypes that influence cell-mediated immunity and HIV-1 disease progression rates

We used cutaneous delayed-type hypersensitivity responses, a powerful in vivo measure of cell-mediated immunity, to evaluate the relationships among cell-mediated immunity, AIDS, and polymorphisms in CCR5, the HIV-1 coreceptor. There was high concordance between CCR5 polymorphisms and haplotype pairs that influenced delayed-type hypersensitivity responses in healthy persons and HIV disease progression. In the cohorts examined, CCR5 genotypes containing -2459G/G (HHA/HHA, HHA/HHC, HHC/HHC) or -2459A/A (HHE/HHE) associated with salutary or detrimental delayed-type hypersensitivity and AIDS phenotypes, respectively. Accordingly, the CCR5-Δ32 allele, when paired with non-Δ32-bearing haplotypes that correlate with low (HHA, HHC) versus high (HHE) CCR5 transcriptional activity, associates with disease retardation or acceleration, respectively. Thus, the associations of CCR5-Δ32 heterozygosity partly reflect the effect of the non-▵32 haplotype in a background of CCR5 haploinsufficiency. The correlations of increased delayed-type hypersensitivity with -2459G/G-containing CCR5 genotypes, reduced CCR5 expression, decreased viral replication, and disease retardation suggest that CCR5 may influence HIV infection and AIDS, at least in part, through effects on cell-mediated immunity.

Predicting the risk for dialysis or death in IgA nephropathy

For the individual patient with primary IgA nephropathy (IgAN), it remains a challenge to predict long-term outcomes for patients receiving standard treatment. We studied a prospective cohort of 332 patients with biopsy-proven IgAN patients followed over an average of 13 years. We calculated an absolute renal risk (ARR) of dialysis or death by counting the number of risk factors present at diagnosis: hypertension, proteinuria ≥1 g/d, and severe pathologic lesions (global optical score, ≥8). Overall, the ARR score allowed significant risk stratification (P < 0.0001). The cumulative incidence of death or dialysis at 10 and 20 years was 2 and 4%, respectively, for ARR=0; 2 and 9% for ARR=1; 7 and 18% for ARR=2; and 29 and 64% for ARR=3, in adequately treated patients. When achieved, control of hypertension and reduction of proteinuria reduced the risk for death or dialysis. In conclusion, the absolute renal risk score, determined at diagnosis, associates with risk for dialysis or death.

Inflammation in chronic kidney disease: role in the progression of renal and cardiovascular disease

Inflammation is the response of the vasculature or tissues to various stimuli. An acute and chronic pro-inflammatory state exists in patients with chronic kidney disease (CKD), contributing substantially to morbidity and mortality. There are many mediators of inflammation in adults with CKD and end-stage kidney disease (ESKD), including hypoalbuminemia/malnutrition, atherosclerosis, advanced oxidation protein products, the peroxisome proliferators-activated receptor, leptin, the thiobarbituric acid reactive system, asymmetric dimethyl arginine, iron, fetuin-A, and cytokines. Inflammation contributes to the progression of CKD by inducing the release of cytokines and the increased production and activity of adhesion molecules, which together contribute to T cell adhesion and migration into the interstitium, subsequently attracting pro-fibrotic factors. Inflammation in CKD also causes mortality from cardiovascular disease by contributing to the development of vascular calcifications and endothelial dysfunction. Similar to the situation in adults, cardiovascular disease in pediatric CKD is linked to inflammation: abnormal left ventricular wall geometry is positively associated with markers of inflammation. This review focuses on traditional and novel mediators of inflammation in CKD and ESKD, and the deleterious effect inflammation has on the progression of renal and cardiovascular disease.

CCR5 deficiency aggravates crescentic glomerulonephritis in mice

The chemokine receptor CCR5 is predominantly expressed on monocytes and Th1-polarized T cells, and plays an important role in T cell and monocyte recruitment in inflammatory diseases. To investigate the functional role of CCR5 in renal inflammation, we induced a T cell-dependent model of glomerulonephritis (nephrotoxic serum nephritis) in CCR5(-/-) mice. Induction of nephritis in wild-type mice resulted in up-regulation of renal mRNA expression of the three CCR5 chemokine ligands, CCL5 (15-fold), CCL3 (4.9-fold), and CCL4 (3.4-fold), in the autologous phase of the disease at day 10. The up-regulated chemokine expression was paralleled by infiltration of monocytes and T cells, followed by renal tissue injury, albuminuria, and loss of renal function. Nephritic CCR5(-/-) mice showed a 3- to 4-fold increased renal expression of CCL5 (61.6-fold vs controls) and CCL3 (14.1-fold vs controls), but not of CCL4, in comparison with nephritic wild-type mice, which was accompanied by augmented renal T cell and monocyte recruitment and increased lethality due to uremia. Furthermore, CCR5(-/-) mice showed an increased renal Th1 response, whereas their systemic humoral and cellular immune responses were unaltered. Because the CCR5 ligands CCL5 and CCL3 also act via CCR1, we investigated the effects of the pharmacological CCR1 antagonist BX471. CCR1 blockade in CCR5(-/-) mice significantly reduced renal chemokine expression, T cell infiltration, and glomerular crescent formation, indicating that increased renal leukocyte recruitment and consecutive tissue damage in nephritic CCR5(-/-) mice depended on functional CCR1. In conclusion, this study shows that CCR5 deficiency aggravates glomerulonephritis via enhanced CCL3/CCL5-CCR1-driven renal T cell recruitment.

Natural history of primary IgA nephropathy

Primary IgA nephropathy (IgAN) is the most frequent type of primary glomerulonephritis worldwide. The characteristic presentation is gross hematuria at the time of an infectious episode. A renal biopsy still is mandatory for the diagnosis. The natural history of the disease is characterized by clinical and pathologic progression over time, which can vary from a few years to more than 50 years. It is possible to make a broad prediction at the time of diagnosis of the long-term (20 years) risk of progressive chronic kidney disease, and then to end-stage renal disease requiring renal replacement therapy (20-year cumulative end-stage renal disease risk range, 14%-39%). The 3 major independent risk factors are arterial hypertension, proteinuria more than 1 g/d, and severe renal histopathologic lesions including hyalinosis, crescents, or defined by histopathologic scoring systems. When any clinical risk factors are present, patients should be targeted closely by appropriate treatments in the following order: (1) precise control of hypertension, (2) control of proteinuria when persisting for greater than 1 g/d, and (3) evidence-based treatment where available for severe lesions. This is a symptomatic treatment strategy because pathogenesis and etiology still remain unclear.

The genetics of IgA nephropathy

IgA nephropathy is the most common form of primary glomerulonephritis. Variations in clinical manifestations indicate that a diagnosis of IgA nephropathy encompasses multiple disease subsets that cannot be distinguished on the basis of renal pathology or clinical variables alone. Familial forms of the disease have been reported throughout the world, but are probably under-recognized because associated urinary abnormalities are often intermittent in affected family members. IgA nephropathy has complex determination, with different genes probably causing disease in different patient subgroups. Of the many pathogenic mechanisms reported, defects in IgA1 glycosylation that lead to formation of immune complexes have been consistently implicated. Here, we present the evidence for genetic contributions to the disease, review clinical patterns of familial disease, and summarize some of the most promising genetic studies conducted to date. Linkage-based approaches to the study of familial forms of the disease have identified significant or suggestive loci on chromosomes 6q22-23, 2q36, 4q26-31, 17q12-22 and 3p24-23, but no causal gene has yet been identified. Many interesting, but poorly replicated, genetic association studies have also been reported. We discuss recent developments in analytic tools that should enable genetic studies of sporadic forms of disease by the genome-wide association approach.

Analysis of the CC chemokine receptor 5 delta32 polymorphism in a Brazilian population with cutaneous leishmaniasis

Patients with mucocutaneous leishmaniasis (MCL) show a vigorous T-cell immune response against Leishmania braziliensis. Because the Th response is associated with inflammation, the non-functional CC chemokine receptor 5 (CCR5) may rely in a less severe inflammatory state. The aim of this study was to investigate the CCR5 gene in a Brazilian population with leishmaniasis compared with healthy control subjects and to determine the progression from cutaneous to MCL in the Delta32 allele carriers. Among 100 patients with Montenegro skin test and indirect immunofluorescence assay (IIF) values positive for leishmaniasis, there were 32% women and 68% men. The patients were 89% CCR5/CCR5, 10% CCR5/Delta32, and 1% Delta32/Delta32, while healthy subjects showed a 91% incidence of CCR5/CCR5, 8% of CCR5/Delta32, and 1% of Delta32/Delta32. The CCR5/CCR5 patients (89%) showed a large spectrum of clinical manifestations, where 22.47% had active mucous lesions and 77.53% had cutaneous lesions. In this work, the Delta32 allele carriers (10%) showed only cutaneous manifestations when compared with wild-type individuals. Finally, with regard to the Delta32 allele carriers, a less severe spectrum of clinical manifestations was observed in comparison with wild-type individuals. Although a lack of mucocutaneous lesions was evident among Delta32 allele carriers, the number of individuals studied was small. Therefore, further investigations are needed to elucidate the role of CCR5 in the clinical aspects of leishmaniasis.

CC-chemokine receptor five gene polymorphism in primary IgA nephropathy: the 32 bp deletion allele is associated with late progression to end-stage renal failure with dialysis

The chemokine (CK) receptor 5 (CCR5) is necessary for two adjacent cysteines (CC)-CKs such as Regulated upon Activation Normal T cell Expressed and Secreted, a/o Macrophage Inflammatory Protein 1alpha/beta to mediate their inflammatory properties. The CCR5 gene polymorphism with 32-basepair deletion (d32) leads to receptor inactivation/dysfunction in homo/heterozygous individuals. We have evaluated its role in both initiation and/or progression of primary immunoglobulin A (IgA) nephropathy (IGAN) in a case-control study involving a prospective cohort of 318 IGAN patients and a matched group of 294 controls. Genotyping was performed by a two-specific primers single polymerase chain reaction technique: normal allele (nl) vs d32 allele. The d32 allele frequency was not different in patients (11.0%) vs controls (8.3%), indicating no significant influence on IGAN initiation. Genotype to clinical phenotype correlation demonstrated that progression to renal/patient death was associated with the d32 allele: 18.2% (12 out of 66 with d32) vs 8.3% (21 out of 252); chi(2)=6.73; P=0.017. The Kaplan-Meier survival without renal/patient death was worse in d32-positive patients (log-rank test; P=0.002). The Cox regression analyses confirmed that the nl/nl genotype was a significant and independent protective factor for progression to end-stage renal failure (ESRF)/dialysis: beta/standard error (s.e.)=-3.1; chi(2)=9.5; relative risk=0.31 (95% confidence interval 0.15-0.65); P=0.002. The d32-CCR5 polymorphism played a significant role in the progression of primary IGAN, with the nl/nl genotype being an independent protective factor for late progression towards ESRF/dialysis. These data raise question about the usefulness of systematic CCR5 genotyping in IGAN patients.

A closed-tube assay for genotyping of the 32-bp deletion polymorphism in the chemokine receptor 5 (CCR5) gene: dissociation analysis of amplified fragments of DNA

We have developed a closed-tube assay for determination of the chemokine receptor type 5 (CCR5) 32-bp deletion allele, which protects against infections with HIV and modulates susceptibility to a variety of inflammatory diseases. This assay utilizes dissociation analysis of amplified products in the presence of Sybr Green I for allele discrimination. After having established robust conditions for the assay, we used it to genotype 590 unknown DNA samples. A blinded comparison with a procedure based upon agarose gel electrophoresis of amplified material revealed complete concordance between the two procedures. Our closed-tube assay is inexpensive and easy to carry out. Furthermore, it reduces or eliminates the risk of carry-over contamination with previously amplified products. The insights gained in this study can be applied to develop assays for genotyping of other insertion/deletion polymorphisms based upon differences in T(m) of allele-specific amplicons.