The Role Of Mannose Binding Lectin In The Pathogenesis Of Systemic Lupus Erythematosus

Objectives1. To detect serum level of mannose binding lectin (MBL) in systemic lupus erythematosus (SLE) patients and healthy blood donors.2. To develope a real-time PCR assay using fluorescence hybridisation probe for the mutation detection of exon 1 at codons 52, 54 and 57, and for the polymorphisms typing in the promoter region at position -550 (H/L) in MBL gene.3. Using the above-mentioned assay to detect the mutation of exon 1 and polymorphisms of the promoter region in MBL gene in SLE patients and healthy blood donors.4. To analyze the relationship of the serum MBL and its genovariation with the clinical manifestations and disease activity indices in Chinese SLE patients, and to investigate primarily the role 'of MBL in the pathogenesis of SLE.MethodsForty SLE patients and 30 healthy blood donors were entered in our study. Serum MBL was measured by ELISA. Genomic DNA was extracted from peripheral blood anticoagulated with EDTA. Haplotype MBL2*LXPA (GenBank X15422 ) was used to design all primers and specific fluorophore-labelled hybridisation probes for exon 1 and promoter regions. The genotyping of MBL exon 1 mutation and promoter polymorphisms in the two groups were performed using real-time PCR through LightCycler Instrument integrated with specific oligonucleotide probes.Results Serologic results: Serum MBL in SLE patients was significantly lowerthan those in healthy blood donors (107.2 vs. 290.2, P=0.0002).Molecularbiologic results: We first successfully developed a real-time PCR assay using fluorescence hybridisation probe for the genovariation detection in MBL gene in china. This method is rapid and provides reliable results and excellent reproducibility. Using this new method, we found that MBL mutation in exon 1 region in Chinese people was mainly at codon 54, with a mutation rate of 37.1 % in SLE group, which was obviously higher than those in control group (13.3%, p=0.049). Polymorphisms of H/L in MBL gene are present in both SLE patients and controls. There were no difference in the presentation of L allele (67.5 % vs. 53.3,%, p>0.05).Relationship between serologic results and clinical manifastations of SLE patients: The prevelence of leukopenia in low MBL group (<100ng/ml) of SLE patients was obviously increased than those with high MBL group( ≥ 100ng/ml). The average SLEDAI value was significantly higher in low MBL group, whose prevelence of SLEDAI ≥ 10 was significantly higher than those with high MBL group. A negative correlation was observed between SLEDAI and serum MBL (r = -0.48, p<0.001).Relationship between molecularbiologic results and clinical manifastations of SLE patients: The prevelence of complement deficiency was abviously increased (100.0% vs. 72.0% , p=0.026) in patients who have MBL mutation at codon 54, at the same time, those patients' SLEDAI value increased significantly (12.87 vs. 7.44, p=0.0029). There was no relationship between polymorphisms of H/L and clinical manifastations in SLE patients.Relationship between serologic and molecularbiologic results: Patients with MBL mutation in codon 54 have a significantly lower serum MBL compare with those without the same mutation (141.7ng/ml vs. 49.8ng/ml, p=0.00027). Though there was no statisticaly difference, patients with L polymorphism have lower serum MBL than those with H...