Anticytoskeletal Autoantibody to Microfilament Novel Focal Contact Proteins Anchorage Sites Recognizes

Abstract Actin microfilaments are anchored to the plasma membrane at focal contacts. Using an indirect immunofluorescence method, we detected an autoantibody reactive with focal contacts in PtK2, HEp-2, and BHK-21 cells in serum from two patients with early systemic sclerosis. With double immunofluorescence, using the actin-binding drug phalloidin, we localized the plaques decorated by these sera specifically at the termini of microfilament bundles. The reactive antigens were identified by immunoblotting as proteins of 80,000-and 75,300-mol wt in PtK2, and of 53,500-mol wt in HEp-2 and BHK-2i cells. The 53,500-mol wt protein was also identified in rat skeletal, myocardial, and smooth muscle tissues. The detergent solubility of these proteins suggested that they may be linked to the plasma membrane. The autoantigens were immunologically distinct from vinculin and a-actinin, two major proteins also known to be concentrated at the ends of microfilament bundles. Our observations suggest that this novel anticytoskeletal autoantibody may identify a novel family of vertebrate cell proteins involved in the linkage of microfilamnents to the plasma membrane at focal contacts

Centrosome proteins: a major class of autoantigens in scleroderma

Autoantibodies to intracellular antigens are a hallmark of autoimmune diseases, although their role in disease pathogenesis is unclear. Centrosomes are organelles involved in the organization of the mitotic spindle and they are targets of autoantibodies in systemic sclerosis (SSc). We used recombinant centrosome autoantigens, centrosome-specific antibodies, and immunoassays to demonstrate that a significant proportion of SSc patients exhibited centrosome reactivity. Two centrosome proteins cloned in our laboratory were used to screen 129 SSc sera by Western blotting. The same sera were screened by immunofluorescence using centrosome-specific antibodies to distinguish centrosomes from nuclear speckles commonly stained by SSc sera. Using these criteria, 42.6% of SSc patients were autoreactive to centrosomes, a larger percentage than reacted with all other known SSc autoantigens. Most centrosome-positive sera reacted with both centrosome proteins and half were negative for other routinely assayed SSc autoantibodies. By these criteria, we have identified a novel class of SSc autoreactivity. Only a small percentage of normal individuals and patients with other connective tissue diseases had centrosome reactivity. These results demonstrate that centrosome autoantibodies are a major component of autoreactivity in SSc and thus have potential in disease diagnosis. Centrosome autoantigens may be useful in studying the development of autoantibodies and chronic inflammation in SSc and perhaps other autoimmune diseases

Pulmonary capillary endothelial metabolic dysfunction - Severity in pulmonary arterial hypertension related to connective tissue disease versus idiopathic pulmonary arterial hypertension

Objective. Pulmonary endothelial dysfunction is intertwined with the development and progression of pulmonary arterial hypertension (PAH). Pulmonary endothelium is an active metabolic tissue in healthy human subjects. This study was undertaken to determine the effects of PAH on pulmonary endothelial angiotensin-converting enzyme (ACE) activity and to identify differences between common PAH types, i.e., PAH related to connective tissue disease (PAH-CTD) versus idiopathic PAH (IPAH). Methods. Nineteen patients with PAH-CTD, 25 patients with IPAH, and 23 control subjects were evaluated. The single-pass transpulmonary percent metabolism (%M) and hydrolysis (both reflecting enzyme activity per capillary) of an ACE synthetic substrate were determined. In addition, the calculated functional capillary surface area (FCSA), normalized to body surface area (BSA), was determined. Results. The %M values in patients with PAHCTD (mean +/- SEM 53.6 +/- 3.6%) were significantly reduced compared with those in control subjects (P < 0.01) and those in patients with IPAH (P < 0.03), but were similar between the IPAH and control groups (mean +/- SEM 66.2 +/- 3.6% and 74.7 +/- 2.7%, respectively). Substrate hydrolysis was also significantly reduced in patients with PAH-CTD. The FCSA/BSA was significantly reduced in patients with PAH-CTD (mean +/- SEM 1,068 +/- 118 ml/minute/m(2)) and in patients with IPAH (1,443 +/- 186 ml/minute/m(2)) compared with that in controls (2,948 245 ml/minute/m2; P < 0.01 for both). At a given cardiac index, the FCSA/BSA tended to be lower in the PAH-CTD group than in the IPAH group. Moreover, unlike in IPAH, a linear relationship between the FCSA/BSA and the diffusing capacity for carbon monoxide (DLCO) was observed in PAH-CTD (r = 0.54, P < 0.03). Conclusion. The metabolically functional pulmonary capillary bed appears to be reduced to an equal extent in PAH-CTD and IPAH. However, %M and hydrolysis appear to be reduced in PAH-CTD but not in IPAH, reflecting relatively diminished ACE activity on the pulmonary capillary endothelial cells of patients with PAH-CTD, and showing that pulmonary endothelial metabolic function differs between PAH types. This study also provides the first functional evidence that a reduced DLCO value in patients with PAH-CTD is related to the degree of FCSA loss

Anti-SMN autoantibodies in mixed connective tissue disease are associated with a severe systemic sclerosis phenotype

Objectives The survival of motor neuron (SMN) complex has an essential role in the assembly of small nuclear ribonucleoproteins (RNP). Recent reports have described autoantibodies (aAbs) to the SMN complex as novel biomarkers in anti-U1RNP+ myositis patients. The aim of this study was to compare phenotypic features of anti-U1RNP+ mixed connective tissue disease (MCTD) patients with and without anti-SMN aAbs.Methods A retrospective MCTD cohort was studied. Addressable laser bead immunoassay was used to detect specific anti-SMN aAbs with <300 mean fluorescence intensity (MFI) as normal reference range, 300–999 MFI as low-titre and ≥1000 MFI as high-titre positivity. Comparison of clinical features between anti-SMN+ and anti-SMN− subgroups used two-tailed Fisher’s exact test, and logistic regression analyses.Results Sixty-six patients were included. Median age at MCTD diagnosis was 40.6 years, and duration of follow-up was 12 years. Based on the highest available titre, 39 (59%) were anti-SMN+: 10 (26%) had low titre and 29 (74%) had high titre. Anti-SMN+ patients had a higher frequency of fingertip pitting scars (anti-SMN+ 23% vs anti-SMN− 4%, p=0.04), lower gastrointestinal (GI) involvement (26% vs 4%, p=0.04), and myocarditis (16% vs 0%, p=0.04). The combined outcome of pitting scars and/or lower GI involvement and/or myositis and/or myocarditis was highest among high-titre anti-SMN+ patients: adjusted OR 7.79 (2.33 to 30.45, p=0.002).Conclusions Anti-SMN aAbs were present in 59% of our MCTD cohort. Their presence, especially at high-titres, was associated with a severe systemic sclerosis (scleroderma) phenotype including myositis, myocarditis and lower GI involvement

Treatment Algorithms in Systemic Lupus Erythematosus

ObjectiveTo establish agreement on systemic lupus erythematosus (SLE) treatment

Treatment algorithms in systemic lupus erythematosus

To establish agreement on systemic lupus erythematosus (SLE) treatment.SLE experts (n = 69) were e-mailed scenarios and indicated preferred treatments. Algorithms were constructed and agreement determined (≥50% respondents indicating ≥70% agreement).Initially, 54% (n = 37) responded suggesting treatment for scenarios; 13 experts rated agreement with scenarios. Fourteen of 16 scenarios had agreement as follows: discoid lupus: first-line therapy was topical agents and hydroxychloroquine and/or glucocorticoids then azathioprine and subsequently mycophenolate (mofetil); uncomplicated cutaneous vasculitis: initial treatment was glucocorticoids ± hydroxychloroquine ± methotrexate, followed by azathioprine or mycophenolate and then cyclophosphamide; arthritis: initial therapy was hydroxychloroquine and/or glucocorticoids, then methotrexate and subsequently rituximab; pericarditis: first-line therapy was nonsteroidal antiinflammatory drugs, then glucocorticoids with/without hydroxychloroquine, then azathioprine, mycophenolate, or methotrexate and finally belimumab or rituximab, and/or a pericardial window; interstitial lung disease/alveolitis: induction was glucocorticoids and mycophenolate or cyclophosphamide, then rituximab or intravenous gamma globulin (IVIG), and maintenance followed with azathioprine or mycophenolate; pulmonary hypertension: glucocorticoids and mycophenolate or cyclophosphamide and an endothelin receptor antagonist were initial therapies, subsequent treatments were phosphodiesterase-5 inhibitors and then prostanoids and rituximab; antiphospholipid antibody syndrome: standard anticoagulation with/without hydroxychloroquine, then a thrombin inhibitor for venous thrombosis, versus adding aspirin or platelet inhibition drugs for arterial events; mononeuritis multiplex and central nervous system vasculitis: first-line therapy was glucocorticoids and cyclophosphamide followed by maintenance with azathioprine or mycophenolate, and then rituximab, IVIG, or plasmapheresis; and serious lupus nephritis: first-line therapy was glucocorticoids and mycophenolate, then cyclophosphamide then rituximab.We established variable agreement on treatment approaches. For some treatment decisions there was good agreement between experts even if no randomized controlled trial data were available