Autoantibodies to RNA polymerases recognize multiple subunits and demonstrate cross-reactivity with RNA polymerase complexes.
OBJECTIVE: To determine the subunit specificity of autoantibody directed to RNA polymerases (RNAP) I, II, and III, which is one of the major autoantibody responses in patients with systemic sclerosis (SSc). METHODS: Thirty-two SSc sera with anti-RNAP antibodies (23 with anti-RNAP I/III, 5 with anti-RNAP I/III and II, and 4 with anti-RNAP II alone) were analyzed by immunoblotting using affinity-purified RNAP and by immunoprecipitation using 35S-labeled cell extracts in which RNAP complexes were dissociated. Antibodies bound to individual RNAP subunits were eluted from preparative immunoblots and were further analyzed by immunoblotting and immunoprecipitation. RESULTS: At least 15 different proteins were bound by antibodies in anti-RNAP-positive SSc sera in various combinations. All 9 sera immunoprecipitating RNAP II and all 28 sera immunoprecipitating RNAP I/III recognized the large subunit proteins of RNAP II and III, respectively. Reactivity to RNAP I large subunits was strongly associated with bright nucleolar staining by indirect immunofluorescence. Affinity-purified antibodies that recognized a 62-kd subunit protein cross-reacted with a 43-kd subunit protein and immunoprecipitated both RNAP I and RNAP III. Antibodies that recognized a 21-kd subunit protein obtained from sera that were positive for anti-RNAP I/III and II antibodies immunoprecipitated both RNAP II and RNAP III. CONCLUSION: Anti-RNAP antibodies recognize multiple subunits of RNAP I, II, and III. Moreover, the results of this study provide the first direct evidence that antibodies that recognize shared subunits of human RNAPs or epitopes present on different human RNAP subunits are responsible for the recognition of multiple RNAPs by SSc sera. (+info)
Interferon-alpha does not improve outcome at one year in patients with diffuse cutaneous scleroderma: results of a randomized, double-blind, placebo-controlled trial.
OBJECTIVE: To determine whether interferon-alpha (IFNalpha) reduces the severity of skin involvement in early (<3 years) diffuse scleroderma. METHODS: In a randomized, placebo-controlled, double-blind trial, 35 patients with early scleroderma received subcutaneous injections of either IFNalpha (13.5 x 10(6) units per week in divided doses) or indistinguishable placebo. Outcomes assessed were the modified Rodnan skin score, as determined by a single observer at baseline, 6 months, and 12 months, as well as data on renal, cardiac, and lung function. Pre- and posttreatment skin biopsy samples were analyzed and blood was obtained for assessment of procollagen peptide levels. RESULTS: There were 11 withdrawals from the IFNalpha group and 3 from the placebo group due to either toxicity, lack of efficacy, or death. In the intent-to-treat analysis, there was a greater improvement in the skin score in the placebo group between 0 and 12 months (mean change IFNalpha -4.7 versus placebo -7.5; P = 0.36). There was also a greater deterioration in lung function in patients receiving active therapy, as assessed by either the forced vital capacity (mean change IFNalpha -8.2 versus placebo +1.3; P = 0.01) or the diffusing capacity for carbon monoxide (mean change IFNalpha -9.3 versus placebo +4.7; P = 0.002). Skin biopsy showed no significant decrease in collagen synthesis in the IFNalpha group, and no significant differences in the levels of procollagen peptides were seen between the 2 groups. CONCLUSION: This study suggests that IFNalpha is of no value in the treatment of scleroderma, and that it may in fact be deleterious. (+info)
Long-term fetal microchimerism in peripheral blood mononuclear cell subsets in healthy women and women with scleroderma.
Fetal CD34(+) CD38(+) cells have recently been found to persist in maternal peripheral blood for many years after pregnancy. CD34(+) CD38(+) cells are progenitor cells that can differentiate into mature immune-competent cells. We asked whether long-term fetal microchimerism occurs in T lymphocyte, B lymphocyte, monocyte, and natural-killer cell populations of previously pregnant women. We targeted women with sons and used polymerase chain reaction for a Y-chromosome-specific sequence to test DNA extracted from peripheral blood mononuclear cells (PBMC) and from CD3, CD19, CD14, and CD56/16 sorted subsets. We also asked whether persistent microchimerism might contribute to subsequent autoimmune disease in the mother and included women with the autoimmune disease scleroderma. Scleroderma has a peak incidence in women after childbearing years and has clinical similarities to chronic graft-versus-host disease that occurs after allogeneic hematopoietic stem-cell transplantation, known to involve chimerism. Sixty-eight parous women were studied for male DNA in PBMC and 20 for PBMC subsets. Microchimerism was found in PBMC from 33% (16 of 48) of healthy women and 60% (12 of 20) women with scleroderma, P =.046. Microchimerism was found in some women in CD3, CD19, CD14, and CD56/16 subsets including up to 38 years after pregnancy. Microchimerism in PBMC subsets was not appreciably more frequent in scleroderma patients than in healthy controls. Overall, microchimerism was found in CD3, CD19, and CD14 subsets in approximately one third of women and in CD56/16 in one half of women. HLA typing of mothers and sons indicated that HLA compatibility was not a requirement for persistent microchimerism in PBMC subsets. Fetal microchimerism in the face of HLA disparity implies that specific maternal immunoregulatory pathways exist that permit persistence but prevent effector function of these cells in normal women. Although microchimerism in PBMC was more frequent in women with scleroderma than healthy controls additional studies will be necessary to determine whether microchimerism plays a role in the pathogenesis of this or other autoimmune diseases. (+info)
Evidence of cell-mediated cardiac myocyte injury involved in the heart failure of a patient with progressive systemic sclerosis.
A 54-year-old woman with progressive systemic sclerosis (PSS) was admitted to hospital because of dyspnea and chest pain. Echocardiogram revealed diffuse hypokinesis of the left ventricle (ejection fraction 24%). Methylprednisolone, heparin, and diuretics were administered, without benefit. Anemia, thrombocytopenia, and renal dysfunction rapidly progressed, and she died of heart failure on the 14th hospital day. Immunohistochemical study of the myocardial tissue showed mild to moderate cell infiltration, mainly consisting of natural killer (NK) cells, macrophages, cytotoxic T lymphocytes (CTLs), and T helper cells. Perforin, a cytolytic factor, was expressed in the infiltrating CTLs and NK cells, indicating that these cells were activated killer cells. Furthermore, human leukocyte antigen classes I and II, intercellular adhesion molecule-1, as well as costimulatory molecules B7-1, B7-2, and CD40, all of which are known not to be expressed in cardiac myocytes under normal conditions, were moderately to strongly expressed in cardiac myocytes. There was no detectable level of enterovirus genomes in the polymerase chain reaction products from the myocardial tissue of this patient. These findings strongly suggest that the infiltrating killer cells recognized cardiac myocytes as target cells and directly damaged them by releasing perforin. Enhanced expression of these antigens may have played an important role in the activation and cytotoxicity of the infiltrating killer cells. Absence of enterovirus genomes in the myocardial tissue may suggest that this autoimmune process is primarily induced by PSS. (+info)
Influence of ethnic background on clinical and serologic features in patients with systemic sclerosis and anti-DNA topoisomerase I antibody.
OBJECTIVE: To investigate the effect of ethnicity on clinical and serologic expression in patients with systemic sclerosis (SSc) and anti-DNA topoisomerase I (anti-topo I) antibody. METHODS: Clinical and serologic features, as well as HLA class II allele frequencies, were compared among 47 North American white, 15 North American black, 43 Japanese, and 12 Choctaw Native American SSc patients with anti-topo I antibody. RESULTS: The frequency of progressive pulmonary interstitial fibrosis was lower, and cumulative survival rates were better in white compared with black and Japanese patients. Sera of white and black patients frequently recognized the portion adjacent to the carboxyl terminus of topo I, sera of Japanese patients preferentially recognized the portion adjacent to the amino terminus of topo I, and sera of Choctaw patients recognized both portions of topo I. Anti-RNA polymerase II and anti-SSA/Ro antibodies were present together with anti-topo I antibody more frequently in sera of Japanese patients than in sera of white patients. The HLA-DRB1 alleles associated with anti-topo I antibody differed; i.e., DRB1*1101-*1104 in whites and blacks, DRB1*1502 in Japanese, and DRB1*1602 in Choctaws. Multivariate analysis showed that ethnic background was an independent determinant affecting development of severe lung disease as well as survival. CONCLUSION: Clinical and serologic features in SSc patients were strongly influenced by ethnic background. The variability of disease expression in the 4 ethnic groups suggests that multiple factors linked to ethnicity, including genetic and environmental factors, modulate clinical manifestations, disease course, and autoantibody status in SSc. (+info)
Pulmonary artery pressure variation in patients with connective tissue disease: 24 hour ambulatory pulmonary artery pressure monitoring.
BACKGROUND: The specific contribution of secondary pulmonary hypertension to the morbidity and mortality of patients with underlying lung disease can be difficult to assess from single measurements of pulmonary artery pressure. We have studied patients with secondary pulmonary hypertension using an ambulatory system for measuring continuous pulmonary artery pressure (PAP). We chose to study patients with connective tissue disease because they represent a group at high risk of pulmonary vascular disease, but with little disturbance of lung function. METHODS: Six patients (five with progressive systemic sclerosis and one with systemic lupus erythematosis) were studied. They underwent preliminary cardiopulmonary investigations followed by Doppler echocardiography, right heart catheterisation, and ambulatory pulmonary artery pressure monitoring to measure changes in pressure over a 24 hour period including during a formal exercise test. RESULTS: All patients had pulmonary hypertension as measured by Doppler echocardiography with estimated pulmonary artery systolic pressures of 40-100 mm Hg. Pulmonary function testing revealed virtually normal spirometric values (mean FEV1 86.9% predicted) but marked reduction in CO gas transfer factor (KCO 57.8% predicted). Exercise responses were impaired with mean VO2max 50.6% predicted. Ambulatory PAP monitoring indicated significant changes in pressures with variation in posture and activity throughout 24 hours. Resting PAP did not predict the change in PAP seen on exercise. CONCLUSION: Conventional methods of assessment of the pulmonary circulation based on single measurements in the supine position may underestimate the stresses faced by the right side of the circulation. This ambulatory system allows monitoring of pulmonary haemodynamics continuously over 24 hours during normal activities of daily living. These measurements may increase our understanding of the contribution made by secondary pulmonary hypertension to the morbidity and mortality of the underlying lung disease. (+info)
Animal model of sclerotic skin. I: Local injections of bleomycin induce sclerotic skin mimicking scleroderma.
We have established a mouse model for scleroderma induced by repeated local injections of bleomycin (BLM). Daily injection of BLM at a dose of >10 microg per ml for 4 wk induced histologic changes of dermal sclerosis, but not fibrosis, with thickened and homogenous collagen bundles and cellular infiltrates in BALB/C mice, whereas clinical signs of scleroderma were not apparent. In addition, lung fibrosis was also induced preceding the cutaneous changes. Sclerotic changes were not found in other sites of the skin distant from the injection site. Dermal sclerosis could also be induced by injecting BLM only every other day. The sclerotic changes of the dermis were sustained after ceasing BLM applications for at least 6 wk. Mast cells gradually increased in number as the sclerotic changes developed. Marked degranulation of mast cells was observed with elevated histamine release. The amount of hydroxyproline in skin was significantly increased at 4 wk of BLM treatment as compared with that in untreated or phosphate-buffered saline-treated mice. Anti-nuclear antibody was detected in serum of BLM-treated mice. Transforming growth factor-beta1 mRNA was detected at an early phase, while transforming growth factor-beta2 mRNA was strongly expressed at 4 wk when the sclerotic features were prominent. These results suggest that dermal sclerosis induced by BLM closely resembles systemic sclerosis both histologically and biochemically. Our mouse model can provide a powerful tool of inducing dermal sclerosis to examine the pathogenesis and the therapeutic approach of scleroderma. (+info)
A potential role for protease nexin 1 overexpression in the pathogenesis of scleroderma.
Scleroderma currently affects approximately 75,000-100,000 individuals in the United States. Fibroblasts isolated from lesional skin of scleroderma patients overexpress collagens and other matrix components, and this abnormality is maintained for multiple passages in culture. To understand the molecular basis for matrix gene overexpression, we performed a differential display comparison of fibroblasts from clinically lesional and nonlesional scleroderma skin. The results suggested that protease nexin 1 (PN1), a protease inhibitor, is overexpressed in scleroderma fibroblasts. Northern blot verification showed that lesional and nonlesional scleroderma fibroblasts had three- to five-fold increased levels of PN1 mRNA compared with healthy fibroblasts. Western analysis showed that scleroderma fibroblasts also secreted more PN1. In situ hybridization of skin biopsy specimens demonstrated PN1 expression in the dermis of four out of six scleroderma patients but no PN1 expression in the dermis of six healthy volunteers. Transient or stable overexpression of PN1 in mouse 3T3 fibroblasts increased collagen promoter activity or endogenous collagen transcript levels, respectively. PN1 mutagenized at its active site and antisense PN1 both failed to increase collagen promoter activity. These results suggest that overexpression of enzymatically active PN1 may play a pathogenic role in the development of the scleroderma phenotype. (+info)