The Effects of Polymorphism in the MCP-1 Gene Regulatory Region on MCP-1 Expression and the Manifestation of Lupus Nephritis

Kim, Hyun Lee; Yang, Seung Hee; Oh, Yoon Kyu; Lee, Jung Eun; Oh, Ji Eun; Yoon, Hyung Jin; Kim, Yon Su; Ahn, Cu Rie; Han, Jin Suk; Kim, Suhng Gwon; Lee, Jung Sang

Abstract

BACKGROUND: Monocyte chemoattractant protein- 1(MCP-1) plays an important role in progression of lupus nephritis.(LN) The genetic polymorphism in the regulatory region would influence clinical manifestations by controlling serum levels of MCP-1.
METHODS
We determined the genotypes of the MCP-1 gene, the secretion of MCP-1 by pheripheral blood monocytes(PBMCs) and transcription activity according to polymorphism on ELISA and luciferase assay. We also correlated serum MCP-1 level with proteinuria according to the genotypes to evaluate the clinical implication of genetic polymorphism in LN.
RESULTS
10 patients with SLE(20%) were AA homozygous, 21(42%) GA heterozygous, and 18(38%) GG homozygous, which was similar with normal controls[AA 9(20%), GA 27(58%), GG 46(22%)](n= 46). By in-vitro stimulation of PBMCs using Phytohemagglutinin, differential expression of MCP-1 appeared according to the genotypes at -2518 position; PBMCs from AA homozygotes 22.37+/-.07 ng/mL, GA 6.98+/-.72 ng/mL, GG 5.48+/-.22 ng/mL. In the luciferase assay, the gene construct with G at -2518 site showed decreased activity to 39% of that showed by A gene construct. In addition, After cells were treated with TNF-alpha 10 ng/mL), the transcription activity of A gene construct was approximately 3 fold greater than that of G gene construct. Levels of serum MCP-1 were significantly higher in patients with SLE(n=89) than normal controls(n=21)(418.17+/-35.30 pg/mL vs. 127.78+/-14.53 pg/mL, respectively; p<0.05). In contrast, there were no significant differences in serum MCP-1 levels between patients with LN, patients without LN and normal controls. Also, correlation between serum MCP-1 levels and proteinuria was not found(r=0.191, p>0.05). But, in patients with LN, levels of serum MCP-1 were significant higher in patients with AA genotype than those of GA genotyes and GG genotypes(p<0.01).
CONCLUSION
MCP-1 gene polymorphism at regulatory region may be a considerable marker for LN and may modulate the level of protein expression. Our study could make it possible to screen high risk individuals, thus help us to develop a practical application of the molecular findings in clinical practice.