Isolation of cDNA clones encoding the human Sm B/B′auto-immune antigen and specifically reacting with human anti-Sm auto-immune sera

A cDNA clone for the human SmB and B′ auto-immune antigens has been isolated by antibody screening of a cDNA expression library. The cDNA clone hybridises with two distinct mRNAs, one of which is expressed in a tissue-specific manner. A fusion protein expressed from the cDNA clone was recognised by a number of sera from systemic lupus erythematosus (SLE) patients containing anti-Sm antibodies but not by sera reactive with other auto-immune antigens. The potential use of this clone in a diagnostic assay for SLE and in elucidating the processes regulating the expression of SmB and B′ is discussed.     

Anti-factor Xa antibodies in patients with antiphospholipid syndrome and their effects upon coagulation assays

IntroductionThe aim of this study was to examine the prevalence and functional effects of antibodies directed against Factor (F)Xa and other serine proteases (SP) in patients with antiphospholipid syndrome (APS).MethodsSerum from patients with APS (n = 59), systemic lupus erythematosus (SLE; n = 106), other autoimmune rheumatic disease (ARD; n = 63) and 40 healthy controls (HC) were tested for IgG activity against thrombin (Thr), FXa, FVIIa, phosphatidylserine (PS)/FXa and antithrombin (AT)-III by enzyme-linked immunosorbent assay (ELISA). Anti-FXa positive IgG were purified to measure their avidity by chaotropic ELISA and functional effects upon clotting time (FXa-ACT) and FXa enzymatic activity (± AT-III).ResultsAnti-FXa IgG were found in patients with SLE (49.1%) and APS (33.9%) (P <0.05) but not in ARD controls and HC. In contrast, anti-Thr and anti-PS/FXa IgG were identified in other ARD and anti-FVIIa IgG were low in all groups. The avidity of APS-IgG to FXa was significantly higher than SLE-IgG (P <0.05). Greatest prolongation of FXa-ACT was observed with APS-IgG and greatest inhibitory effect upon FXa enzymatic activity was found with APS-IgG followed by SLE-IgG compared to HC-IgG. ATIII inhibition of FXa was significantly reduced by APS-IgG compared with HC and SLE (P <0.05) and did not correlate with binding to AT-III.ConclusionAPS anti-FXa IgG have higher avidity to FXa and greater effects upon the enzymatic and coagulant activity of FXa compared with SLE anti-FXa IgG. Further studies of anti-FXa antibodies in APS, SLE and other non-autoimmune thrombotic disease cohorts are now required to evaluate whether targeting FXa with selective inhibitors in patients bearing anti-FXa antibodies may be an effective treatment strategy.     

Genetic variation in TIMP1 but not MMPs predict excess FEV1 decline in two general population-based cohorts

Background

An imbalance in Matrix MetalloProteases (MMPs) and Tissue Inhibitors of MMPs (TIMPs) contributes to Chronic Obstructive Pulmonary Disease (COPD) development. Longitudinal studies investigating Single Nucleotide Polymorphisms (SNPs) in MMPs and TIMPs with respect to COPD development and lung function decline in the general population are lacking.

Methods

We genotyped SNPs in MMP1 (G-1607GG), MMP2 (-1306 C/T), MMP9 (3 tagging SNPs), MMP12 (A-82G and Asn357Ser) and TIMP1 (Phe124Phe and Ile158Ile) in 1390 Caucasians with multiple FEV₁ measurements from a prospective cohort study in the general population. FEV₁ decline was analyzed using linear mixed effect models adjusted for confounders. Analyses of the X-chromosomal TIMP1 gene were stratified according to sex. All significant associations were repeated in an independent general population cohort (n = 1152).

Results

MMP2 -1306 TT genotype carriers had excess FEV₁ decline (-4.0 ml/yr, p = 0.03) compared to wild type carriers. TIMP1 Ile158Ile predicted significant excess FEV₁ decline in both males and females. TIMP1 Phe124Phe predicted significant excess FEV₁ decline in males only, which was replicated (p = 0.10) in the second cohort. The MMP2 and TIMP1 Ile158Ile associations were not replicated. Although power was limited, we did not find associations with COPD development.

Conclusions

We for the first time show that TIMP1 Phe124Phe contributes to excess FEV₁ decline in two independent prospective cohorts, albeit not quite reaching conventional statistical significance in the replication cohort. SNPs in MMPs evidently do not contribute to FEV₁ decline in the general population.