Disease Severity Rheumatoid Arthritis , Systemic Lupus Erythematosus , Lupus Nephritis , and 32 Deletion Status with ∆ Lack of Association of C-C Chemokine Receptor 5 KALLENBERG and

Objective. C-C chemokine receptor 5 (CCR5) plays an important role in inflammation. A 32 base-pair (∆32) deletion in the CCR5 gene leads to a nonfunctional receptor. This deletion has been reported to have a protective effect on the development and progression of several autoimmune diseases. We investigated whether the ∆32 deletion is associated with disease susceptibility in a population of patients with rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), and lupus nephritis (LN); and whether it is associated with disease severity. Methods. DNA samples from 405 RA patients, 97 SLE patients, 113 LN patients, and 431 healthy controls were genotyped for the CCR5 ∆32 deletion. Differences in genotype frequencies were tested between patients and controls. Association of genotypes with disease severity was analyzed. Results. Genotype frequencies of each group were in Hardy-Weinberg equilibrium. The genotype frequencies of patients did not differ significantly from controls (CCR5/∆32, ∆32/∆32: RA 18.3% and 1.2%, respectively; SLE 17.5% and 2.1%; LN 13.3% and 1.8%; controls 20.0% and 2.8%). However, there was a trend for lower ∆32 deletion allele frequency in LN patients compared to controls (p = 0.08). There was no significant association between the CCR5 status and disease severity in RA, SLE, or LN. Conclusion.Although an association with LN cannot be excluded, the CCR5 ∆32 deletion does not seem to be a disease susceptibility genotype for RA, SLE, or LN. No significant effect of the ∆32 deletion on disease severity was demonstrated. (First Release August 1 2010; J Rheumatol 2010;37:2226–31; doi:10.3899/jrheum.091468) Key Indexing Terms: C-C CHEMOKINE RECEPTOR 5 ∆32 BASE-PAIR DELETION SYSTEMIC LUPUS ERYTHEMATOSUS RHEUMATOID ARTHRITIS LUPUS NEPHRITIS From the Department of Rheumatology and Clinical Immunology, Department of Nephrology, and Department of Genetics, University Medical Center Groningen, Groningen; Department of Nephrology, Radboud University Nijmegen Medical Center, Nijmegen; Department of Rheumatology and Clinical Immunology, University Medical Center, Utrecht; Department of Rheumatology, VU University Medical Center, Amsterdam; and Department of Nephrology, Leiden University Medical Center, Leiden, The Netherlands. The first and second Dutch Lupus Nephritis studies were supported by the Dutch Kidney Foundation (C94.1363; C02.2023; C02.2005), the Dutch League against Rheumatism (grant 735), and The Netherlands Organization for Scientific Research NOW (920-03-115). H.A. Martens, PhD, Department of Rheumatology and Clinical Immunology; S. Gross, Department of Nephrology; G. van der Steege, Department of Genetics; E. Brouwer, PhD, Department of Rheumatology and Clinical Immunology, University Medical Center Groningen; J.H.M. Berden, PhD; R. de Sevaux, PhD, Department of Nephrology, Radboud University Nijmegen Medical Center; R.H.W.M. Derksen, PhD, Department of Rheumatology and Clinical Immunology, University Medical Center, Utrecht; A.E. Voskuyl, PhD, Department of Rheumatology, VU University Medical Center; S.P. Berger, PhD, Department of Nephrology, Leiden University Medical Center; G.J. Navis, PhD, Department of Nephrology; C.G.M. Kallenberg, PhD; M. Bijl, PhD, Department of Rheumatology and Clinical Immunology, University Medical Center Groningen. Address correspondence to Dr. H.A. Martens, Department of Rheumatology and Clinical Immunology, University Medical Center Groningen, PO Box 30001, 9700 RB Groningen, The Netherlands. E-mail: h.martens@maartenskliniek.nl Accepted for publication June 23, 2010. Chemokines, a family of proteins that play an important role in inflammation, attract inflammatory cells such as leukocytes, lymphocytes, and macrophages by interacting with chemokine receptors that are expressed on the surface of these cells. Chemokines are important in homeostatic as well as in inflammatory conditions. In several autoimmune diseases, an enhanced level of chemokines and increased expression of chemokine receptors have been found. One of these receptors, C-C chemokine receptor 5 (CCR5), has several ligands, including CCL5/RANTES (regulated on activation, normal T cell expressed and secreted). CCR5 is highly expressed on T lymphocytes and is important for recruitment of T cells1,2. A deletion of 32 base pairs (∆32 bp deletion) in the gene encoding for CCR5 leads to the proJournal of Rheumatology The on January 20, 2015 Published by www.jrheum.org Downloaded from 2227 Martens, et al: CCR5 ∆32 BP deletion duction of a nonfunctional receptor. The clinical importance of this deletion was first demonstrated in human immuno deficiency virus (HIV) infection, where CCR5 acts as an important coreceptor. In HIV, homozygosity for the ∆32 bp deletion leads to almost 100% resistance against the HIV virus3. Subsequently, the ∆32 bp deletion was also reported to have a protective effect on susceptibility for several autoimmune diseases such as rheumatoid arthritis (RA)4, on progression of (inflammatory) kidney diseases, and on solid organ allograft rejection5. The ∆32 bp deletion has been reported to have a protective effect against the development of RA4. In established RA, the ∆32 bp deletion seems to influence disease severity6,7. However, results have been conflicting8,9. In patients with systemic lupus erythematosus (SLE), there are few data on the role of the ∆32 bp deletion. Although in 2 studies no direct correlation of the ∆32 bp status with SLE was found10,11, another study reported an increased risk for SLE in subjects with the ∆32 bp deletion12. In a mouse model of SLE, expression of chemokines and the CCR5 receptor was highly associated with the development and progression of renal disease (lupus nephritis, LN)13,14. Also in human LN, increased expression of CCR5-positive cells was found5. To date, except for the study by Mamtani, et al12, no study has focused on the role of the CCR5 ∆32 bp deletion in LN. Thus CCR5 may play a role in several autoimmune diseases, including RA and SLE. We evaluated the association of the CCR5 ∆32 bp status with susceptibility for RA and SLE. In addition to studying a large, well defined, and stable founder population of RA and SLE patients, we analyzed a large, well defined and homogeneous population of patients with LN. Further, we determined whether the ∆32 bp deletion is associated with disease severity in RA, SLE, and LN. MATERIALS AND METHODS Patient selection. RA. In 2002, all RA patients who fulfilled the American College of Rheumatology (ACR) criteria for RA15 treated at the University Medical Center Groningen (UMCG) were asked to participate in a study on genetic predisposition of RA. In total, 405 patients were included. In a subgroup of 107 patients, prospective information on disease severity was available. This included cumulative C-reactive protein (CRP) levels over a period of 24 months, Disease Activity Score (DAS) according to Van der Heijde with 3 variables (number of swollen joints, erythrocyte sedimentation rate, Ritchie articular index)16 at disease onset, Ritchie articular index17, and progression of erosions after 24 months of followup (measured by the modified Sharp-van der Heijde score18). Also rheumatoid factor and anti-cyclic citrullinated peptide (anti-CCP) levels were available. SLE. In the period November 2000 to November 2001 we contacted all patients with SLE treated at UMCG to invite them to participate in a study on the genetic predisposition of SLE. All patients met ACR criteria for SLE19. In total, 106 patients were eligible. Nine of these patients, however, were already included in the lupus nephritis studies (see below), so 97 SLE patients were included for further analysis. Lupus nephritis. From September 1995 until November 2006, patients with biopsy-proven proliferative LN (World Health Organization ISN/RPS class III or IV) were included in the first and second Dutch LN studies. Patients included in this study were treated according to a protocol (first study: azathioprine combined with methylprednisolone and prednisone versus cyclophosphamide with prednisone20; second study: prednisone with cyclophosphamide followed by mycophenolate mofetil). Blood samples were available for genetic analysis from 113 of these patients. In LN, proteinuria and creatinine clearance results (measured by the Cockcroft-Gault formula) at the time of inclusion, after 5 months, and after 30 months of therapy were used as markers for disease severity. If the followup was shorter than 30 months, the last available followup data were included. Treatment failure was defined as a renal relapse requiring escalation of therapy or renal failure requiring dialysis or renal transplant. In addition, complement C3 and C4 levels and anti-dsDNA antibody levels at baseline were available. Controls. Partners of patients included in the study of the RA and SLE patients of the UMCG cohort were included as controls. Controls had no RA or SLE. Additional healthy controls were included from a study of risk for development of colorectal cancer as described21. These controls also