Histopathological study of mixed connective tissue disease from 32 autopsy cases in Japan

In order to identify the histological specificity of newly defined connective tissue disease, we examined 32 autopsy cases of mixed connective tissue disease (MCTD) which fulfilled the disease criteria proposed by the Japanese MCTD Committee. The age of the 32 cases ranged from 19 to 79 with an average age of 43 years. The male: female ratio was 3∶29. The duration of illness was 7.9 years on average. These tendencies were not so specific compared with other connective tissue diseases. In reference to the cause of death, pulmonary hypertension associated with severe pulmonary arterial lesions such as plexogenic arteriopathy and intimal thickening was found in 16 cases, which was 34% of all total autopsy cases. Totally pulmonary diseases including pulmonary hypertension, pulmonary fibrosis and interstitial pneumonitis amounted to half of all fatal cases. Following pulmonary disease, esophageal fibrosis, sialoadenitis and cardiac involvement succeeded. Although clinical signs such as dysphagia or hypomotility did not necessarily present before death, the frequency and severity of histological changes of the esophagus cannot be ignored. Accompanied with sicca syndrome, the salivary gland showed variable stages of inflammatory changes from slight lymphocytic infiltration in the periductal region to severe parenchymatous atrophy with severe fibrosis. Autopsy cases of MCTD disclosed myocardial damage in not a few cases, which were often accompanied with fibrosis, and these features were very similar to the those of esophageal lesions. On the other hand, involvement of the kidney, skin and muscle was very slight in MCTD compared with those of systemic lupus erythematosus, progressive systemic sclerosis and polymyositis/dermatomyositis. The kidney lesion was characterized by membranous glomerulonephritis. Skin continued to be scleroedematous in spite of long term illness. Muscle showed slight lymphocytic infiltration around small vessels and interstitium. In addition to serological and clinical features, histopathological study revealed specific features of MCTD different from other connective tissue diseases. In treatment and follow-up of the patients of MCTD, special care should be paid to the conditions of this disease which reflect the histological changes as presented here.     

Clinical profiles of patients with antibodies to nuclear ribonucleoprotein

Summary Currently there are no widely accepted criteria for the diagnosis of MCTD. In this work we attempted to define the clinical profile of a group of 68 patients with anti nRNP antibodies, detected by immunoprecipitation in 0.6% agarose. The diagnosis of each collagen vascular disease was established in every patient, who met with the strict diagnostic criteria either at clinical presentation or during the follow-up period. Twenty-eight patients had SLE, 9 had classical erosive RA, three had PSS and one had PM. The only distinctive features in the group of SLE with anti nRNP was an increased incidence of anti Sm antibodies (p<0.05). In the RA group there was a trend towards a high frequency of Raynaud's phenomenon and swollen hands. At clinical presentation twenty-seven patients did not fulfil enough criteria to be diagnosed of any of the well-defined collagen vascular disease. They presented an undifferentiated syndrome, characterized clinically by Raynaud's phenomenon (100%), swollen hands (88.9%) and joint symptoms (88.9%), with scarce tendency of developing severe systemic manifestations. The main laboratory abnormalities in this group were hipergammaglobulinemia, mildly increased ESR, abnormal levels of CIC, negative anti nDNA and anti Sm antibodies, and the virtual absence of hipocomplementemia. During a clinical course of 96±72.5 months only one patient evolved into another collagen disease (SLE). The clinical course in the remaining cases, was stable improving with low doses of prednisone and/or NSAID. We suggest considering this undifferentiated syndrome as a distinct entity, for which the already classical term of MCTD could be reserved.     

Human urinary trypsin inhibitor bolus infusion improved severe interstitial pneumonia in mixed connective tissue disease

Interstitial pneumonia (IP) with mixed connective tissue disease (MCTD) often progresses despite immunosuppressive therapies that caused serious infections. Human urinary trypsin inhibitor (UT) inhibits inflammatory factors associated with IP, without immunosuppression. UT bolus infusion rescued a female MCTD patient with refractory IP and severe opportunistic fungal pneumonia. Her IP diminished with monthly UT bolus infusion despite tapering of prednisolone, without UT-related side effects. UT pulse therapy could prove beneficial for refractory IP in MTCD even with opportunistic infections.     

A case of mixed connective tissue disease complicated with thrombotic thrombocytopenic purpura

Thrombotic thrombocytopenic purpura (TTP) is a rare complication of mixed connective tissue disease (MCTD). In this report, we describe the case of a 73-year-old Japanese woman with MCTD who developed fever, thrombocytopenia, and microangiopathic hemolytic anemia and was diagnosed with MCTD together with TTP. The activity of von Willebrand factor (vWF) cleaving metalloprotease ADAMTS13 was low and considered to have contributed to the disease activity of TTP. The patient died despite intensive treatment of plasma exchange (PEX) and steroid pulse therapy. Autopsy results revealed that the kidneys had platelet and fibrin thrombi, which occluded capillaries and arterioles. These findings were compatible with TTP and the decreased activity of ADAMTS13 was considered to be associated with the disease activity of TTP.     

A case of mixed connective tissue disease associated with macrovascular lesions in the upper and lower extremities

Macrovascular disease in the setting of mixed connective tissue disease (MCTD) is associated with high rates of morbidity. We describe a 29-year-old woman with MCTD who presented with stenoses of the left radial and left posterior tibial arteries. Blood flow was restored successfully with an intra-arterial infusion of prostaglandin (PG) E₁ followed by oral PGE₁ therapy. The association between macrovascular disease and MCTD, the effectiveness of PGE₁ therapy, and the usefulness of Doppler flow measurements are discussed.     

Anticyclic citrullinated peptide antibodies in patients with mixed connective tissue disease

The clinical significance of anticyclic citrullinated peptide (CCP) antibodies in patients with mixed connective tissue disease (MCTD) was assessed. Altogether, 86 sera from MCTD patients, 96 from rheumatoid arthritis (RA) patients, 42 from systemic lupus erythematosus (SLE) patients, 23 from systemic sclerosis (SSc) patients, 21 from poymyositis/dermatomyositis (PM/DM) patients, and 17 from those with Sjögrens syndrome (SjS) were tested for anti-CCP antibodies using an enzyme-lined immunosorbent assay. Among the 96 RA patients, anti-CCP antibodies were detected in 85%, with the frequency being significantly higher than in MCTD, SLE, SSc, PM/DM, and SjS patients (9%, 14%, 13%, 14%, and 18%, respectively; P < 0.001). Among eight MCTD patients who fulfilled the diagnostic criteria for RA, only 50% had anti-CCP antibodies, and the prevalence was significantly lower than for all RA patients (p < 0.01). All eight patients who fulfilled the criteria for RA had overlap of SLE and SSc, except one patient, whereas the four anti-CCP-positive patients who did not fulfill the criteria for RA had SjS without overlapping features of SLE and SSc; moreover, most of their antibody titers were low. These results suggested that anti-CCP antibodies are associated with RA in MCTD patients, but careful diagnosis of RA is required if patients with low titers of anti-CCP antibodies lack overlapping SLE and SSc.     

Human voltage-dependent anion selective channel 1 is a target antigen for antiglomerular endothelial cell antibody in mixed connective tissue disease

The purpose of this study was to identify the endothelial cell antigens that react with circulating antiendothelial antibody (AECA) in mixed connective tissue disease (MCTD). We screened serum AECA reactivity in 23 patients with MCTD using a human glomerular endothelial cell (HGEC) cellular ELISA. Proteomics, two-dimensional gel electrophoresis and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry were used to identify the endothelial cell antigens of HGECs that reacted with serum antibodies from MCTD patients. Sera from 12 patients (52.0%) were positive for anti-HGEC antibody based on cellular ELISA. MALDI-TOF mass spectrometry used in combination with immunoblotting using serum antibody revealed one protein spot that represented a 36-kDa cell component of HGECs, with an isoelectric point (IP) of about 9, which had a high homology with the voltage-dependent anion-selective channel 1 (VDAC-1). This protein spot was confirmed to react with the antibody specific to VDAC-1. This is the first report of the presence of antibody to VDAC-1 from HGECs in the sera from MCTD patients. Although future studies will be needed to clarify the disease specificity of the a-VDAC-1 antibody in MCTD, the results show that modern proteomics technology is useful for identifying antigens that react with AECA in autoimmune diseases such as MCTD.     

Altered Th17 cells and Th17/regulatory T-cell ratios indicate the subsequent conversion from undifferentiated connective tissue disease to definitive systemic autoimmune disorders

A shift in the balance between Th17-cells and regulatory T-cells (Treg) is an important feature of systemic autoimmune diseases (SAID), and may also contribute to their development. Hereby, we assessed the distribution of peripheral Th17 and Treg-cells in patients with undifferentiated connective tissue disease (UCTD), the forerunner of SAIDs and followed these parameters during the development towards definitive SAIDs. Fifty-one UCTD patients were investigated and followed-up for 3 years. Flow cytometry was used to identify and follow three cell-populations: Th17-cells (CD4+IL-17+ T-cells), natural regulatory T-cells (CD4⁺CD25^brightFoxP3⁺; nTregs) and IL-10 producing Type-1 regulatory T-cells (CD4+IL-10+ T-cells; Tr1). Altogether 37.3% of these patients progressed into SAIDs. Th17-cells were increased in UCTD vs. controls, which further increased in those, whom developed SAIDs eventually. The Th17/nTreg ratio gradually increased from controls through UCTD patients, reaching the highest values in SAID-progressed patients. Regarding the Th17/Tr1 ratios, a similar tendency was observed moreover Th17/Tr1 could distinguish between UCTD patients with, or without subsequent SAID progression in a very early UCTD stage. Various immunoserological markers showed association with Th17 and Th17/nTreg at baseline, indicating the consecutive development of a distinct SAID. The derailed Th17/Treg balance may contribute to disease progression therefore could function as a prognostic marker.     

Anti-cyclic Citrullinated Peptide Antibodies are Highly Associated with Severe Bone Lesions in Rheumatoid Arthritis Anti-CCP and Bone Damage in RA

In the present study we investigated the predictive value of anti-cyclic citrullinated peptide antibodies (anti-CCP) in early rheumatoid arthritis (RA) with respect to the bone damage.

Fifty-four patients with early RA (onset <12 months), 35 classified as established RA (onset >12 months), 33 healthy donors and 76 non-RA autoimmune diseases, were enrolled. Anti-CCP and IgG, IgA, IgM rheumatoid factors (RFs) were determined at baseline. Disease activity score (DAS 28) was calculated at the entry. Bone involvement was evaluated by X-rays and sonography.

The specificity of anti-CCP was 98.4%; significantly (?p<0.01) higher than those of the IgM- (86.0%), IgA- (86.0%) and IgG-RFs (66.2%), respectively. Anti-CCP were detected in 23/54 (42.6%) early RA patients and in 16/35 (45.7%) established RA patients. In the early RA group, 6/33 (18.2%) of the patients without bone lesions, 12/16 (75%) with juxta-articular osteoporosis (JO) and 5/5 with joint erosions (JE) resulted positive showing a significant (?p<0.001) difference between the groups without and with radiological damage.

In the established RA group a significant (?p<0.01) difference being between the group without radiological damage and that with JE was found. Finally, in patients without radiological lesions, examined by ultrasound, anti-CCP antibodies were detected only in subjects with pathologic findings (31.25%).

Data here reported confirm that the presence of anti-CCP are specific for diagnosis of RA, of recent onset also and they are potentially useful as prognostic index of bone involvement.     

Osteoporosis in mixed connective tissue disease

The existence of osteoporosis in 58 postmenopausal women with mixed connective tissue disease (MCTD) was investigated. The mean bone mineral density assessed by dual energy X-ray absorptiometry in the lumbar spine was decreased in 25.8% of the patients, reflecting osteoporosis (T score < –2.5). In the femoral neck there was no significant difference between the BMD of MCTD patients and that of age-matched, healthy postmenopausal women. Low bone mineral density was found among patients on, as well as off, corticosteroids. The extent of bone loss was associated with disease duration, as well as corticosteroid therapy. Serum osteocalcin levels were lower in MCTD patients than in controls. Lower serum oestradiol, testosterone and dehydroepiandrosterone sulphate levels were detected in MCTD patients than in controls. Thus, MCTD may be associated with increased bone loss. Pathogenic factors may include the disease itself, corticosteroid therapy, impaired osteoblast function, and low serum sex hormone levels.