Background Lupus Nephritis (LN) is one of the most frequent manifestations of SLE and can be present in 60% of SLE patients. It has been shown that structural changes and inflammatory infiltrate associated with LN contribute to a hypoxic state which induces angiogenesis . Angiogenesis is a complex process that requires interaction between different cell types, the extracellular matrix, several cytokines and growth factors.
Objectives We proposed to study gene expression levels of angiogenic factors such as VEGF-A (Vascular Endothelial Growth Factor), VCAM-1 (Vascular cell adhesion molecule 1), TGF-β (Transforming Growth Factor), SEL-E (Selectin-E), ANGPT1 (Angiopoietin 1), AGT (Angiotensinogen) and END (Endostatin) in kidney biopsies from LN patients and their relationship with LN severity.
Methods Thirty two kidney biopsies samples were obtained from 32 LN patients and then classified according to ISN/RPS scoring system  in two groups, Class I/Class II biopsies (n=11, 10F/1M, age: 34.64±15.10, range: 21-72) and Class IV biopsies (n=21, 16F/5M, age: 30.95±11.36, range: 17-64). RNA was isolated using TRIzol-Chloroform technique and then was reverse-transcribed using random primers.
Gene expression level of pro-angiogenic factors: VEGF, VCAM-1, TGF-β, SEL-E, ANGPT-1 and anti-angiogenic factors: AGT and END were evaluated using Quantitative Real Time PCR (QPCR). The threshold cycle (Ct) scores were averaged for calculations of relative expression values. The Ct scores were normalized against Ct scores by subtracting β2Microglobuline (β2M) control, or ΔCt=Ct,gene- Ct,B2M. To test for differential gene expression between groups, a two sample T-test was performed to compare the ΔCt in the two groups.
Results ΔCt is inversely proportional to the gene expression level. Significant differences between groups were found in pro-angiogenic genes VEGF-A (p=0,05), VCAM-1 (p=0,05) and in anti-angiogenic gene END (p=0,05) (Table 1). There were not statistically significant differences in the expression of AGT, ANGPT-1, SEL-E and TGF-β between groups. After T test, we evaluated data from ΔCt analysis observing that the levels of mRNA of VEGF-A and VCAM-1 in Class I/II group were higher than those from Class IV group. Conversely, END gene expression was decreased in Class I/II group.
Conclusions In the present cross-sectional study, increased levels of VEGF-A and VCAM-1 and decreased levels of END were observed in biopsies classified as Class I and II. These findings could be associated with angiogenesis process in early stages of the disease. Angiogenesis in progression to LN deserves further evaluation.
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Weening JJ. et al. The classification of glomerulonephritis in systemic lupus erythematosus revisited. Kidney Int: 65 (2):521-30. 2004.
Disclosure of Interest None declared