Microvascular deposition of complement membrane attack complex in dermatomyositis

The role of microvascular injury in the pathogenesis of cutaneous lesions of dermatomyositis

Although microvascular injury has been postulated as the pathogenetic basis of skeletal muscle injury in dermatomyositis (DM), its role in the genesis of the skin lesions, which are said to be difficult to distinguish light microscopically from systemic lupus erythematosus (SLE) and subacute lupus erythematosus (SCLE), has not been analyzed. The authors' intention was to assess the role of microvascular injury in the pathogenesis of skin lesions in DM, SLE, and SCLE. Light microscopic features of biopsies of lesional skin from 20 patients with myopathic DM and 11 with amyopathic DM were compared to eight lesional skin biopsies from eight patients with SLE and 12 lesional skin biopsies from 12 patients with SCLE. Vascular density was compared in the three groups using an immunohistochemical preparation with an antibody to factor VIII. In 12 biopsies from the DM group, and in 19 of 20 lupus erythematosus (LE) specimens, frozen tissue was available. An indirect immunofluorescence methodology was used to detect C5b-9 deposition, and direct immunofluorescence studies for other immunoreactants were performed in standard fashion. Compared with LE, lesions of DM showed a greater degree of endothelial injury, vascular ectasia, and vascular fibrin deposition; there were no differences between myopathic versus amyopathic DM. C5b-9 deposition in vessels was significantly greater in DM than in LE. The superficial vascular plexus density was reduced in lesions of DM versus LE control groups with the greatest reduction observed in myopathic DM. Epithelial injury and mucin was greatest in myopathic DM. Microvascular injury is the apparent pathophysiological basis of skin lesions in DM. Careful attention to microvascular pathology enables distinction of DM from SLE and SCLE. Indirect immunofluorescence testing using a monoclonal antibody to C5b-9 is a valuable tool to distinguish DM from LE in biopsies of lesional skin.

Update on the use of intravenous immune globulin in the treatment of patients with inflammatory muscle disease

The inflammatory myopathies consist of three distinct groups: dermatomyositis, polymyositis, and inclusion body myositis. Dermatomyositis is distinguished by its characteristic rash, while polymyositis is a diagnosis of exclusion. Inclusion body myositis is characterized by early involvement of distal muscle groups and the quadriceps. Definitive diagnosis is made by muscle biopsy, which demonstrates histological features characteristic for each disorder. Immune mechanisms play a role in the pathogenesis of the inflammatory myopathies. A complement-mediated microangiopathy is seen in dermatomyositis, while there is evidence for a T cell-mediated process in polymyositis and inclusion body myositis. Treatment with prednisone is helpful to a majority of patients for a period of time. Immunosuppressive drugs have met with limited success. We describe a group of patients with dermatomyositis, resistant to available therapies, whose muscle strength, skin changes, and muscle biopsies improved significantly during treatment with intravenous immune globulin. The treatment of polymyositis and inclusion body myositis with intravenous immune globulin is currently under study.

Treatment of childhood dermatomyositis with high dose intravenous immunoglobulin

Two children with chronic dermatomyositis who were treated with intravenous immunoglobulin (IVIG) for 28 and 12 months, respectively, are reported. Both patients had received prednisone and immunosuppressive agents prior to IVIG treatments and had experienced significant side effects. Strength and functional abilities improved in both patients in a gradual stepwise fashion with IVIG treatment. One patient achieved remission and continues to do well without any immunosuppressive agents; in the other patient, the dose of oral steroids was reduced and other immunosuppressive agents were discontinued. Use of IVIG was associated with headaches, nausea, and vomiting in both patients. IVIG was an useful adjuvant therapy in these 2 children with dermatomyositis without any significant side effects.

Juvenile dermatomyositis. Pathophysiology and disease expression

In summary, the child who develops the symptoms of the specific rash, proximal muscle weakness, or fatigue should seek medical care promptly. With the advances in physical and medical therapy, many of the consequences of the disease can now be ameliorated. Data suggest that JDMS and PM may each have a different pathophysiology, but more evidence is needed. The next few years will be exciting as there is a national effort by an increased number of investigators to determine the epidemiologic and genetic factors that influence JDMS disease susceptibility and severity.

Inflammatory myopathies

New information regarding myositis specific autoantibodies, histopathologic analysis of muscle biopsy specimens, and immunogenetic features of the different serologic subsets of disease has greatly increased our understanding of the pathogenesis of the inflammatory myopathies. The clinical descriptions of inclusion body myositis and 'amyopathic dermatomyositis' (Euwer and Sontheimer, 1993) are examples of our expanded descriptive capabilities in the evaluation of patients with myopathy. Finally, newer techniques such as cytokine analysis and magnetic resonance imaging may help in the ongoing assessment of disease activity in patients with myositis. The combination of these recently described clinical and laboratory parameters are enough to force a reconsideration of the previously described classification and diagnostic criteria in the inflammatory myopathies.

X-linked vacuolated myopathy: complement membrane attack complex on surface membrane of injured muscle fibers

We describe a probable recessive X-linked myopathy characterized by the presence of vacuolated muscle fibers. Four males and their shared maternal grandfather were affected. Clinical characteristics include juvenile onset, very slow progression, and predominant proximal muscle involvement. The clinical picture and the morphological findings are compared with those previously described in a family. By immunofluorescence, all histologically abnormal muscle fibers, in particular those vacuolated, showed a strong deposition of the complement C5b-9 membrane attack complex over the whole muscle fiber surface. Weak immunostaining for membrane attack complex was also found in endomysial capillaries and perimysial vessel walls. Muscle fibers showed sarcolemmal immunolabeling with anti-major histocompatibility complex I, which was also present on the margins of many vacuoles. All vacuoles were stained by antidystrophin antibody, which colocalized in most of them with antilaminin immunostaining. Taken together, these results suggest that the deposition of membrane attack complex on the damaged cell surface membrane could be important in the pathogenesis of this muscle disorder, and that the membrane-bounded vacuoles could be a consequence of sarcolemmal invagination.

Immunopathogenesis of inflammatory myopathies

Immune-mediated mechanisms appear to play a primary role in the pathogenesis of polymyositis (PM) and dermatomyositis (DM). The serum of patients with active DM has high levels of circulating complement fragments C3b, C4b, and C5b-9 membranolytic attack complex (MAC) and demonstrates a very high C3 uptake in an vitro assay system. The MAC and the immune complex-specific C3bNEO fragment are deposited on the endomysial capillaries early in the disease and lead sequentially to loss of capillaries, muscle ischemia, muscle fiber necrosis, and perifascicular atrophy. In contrast, in PM the muscle fiber injury is initiated by sensitized CD8+ cytotoxic T cells that recognize heretofore unknown and probably endogenous muscle antigens in the context of major histocompatibility complex (MHC) class I expression. A restricted (oligoclonal) pattern of T-cell receptor with prominence of Va1, Vb6, and Vb15 genes is noted within the endomysial infiltrates suggesting that the T-cell response is antigen driven. In both PM and DM, intercellular adhesion molecule (ICAM)-1 and vascular cell adhesion molecule (VCAM)-1 are upregulated in the endomysial endothelial cells and function as ligands for the leukocyte integrins leukocyte function-associated antigen (LFA)-1 and very late activating antigen (VLA)-4, allowing activated lymphocytes to adhere to the endothelial cells and migrate to the muscle fibers. Among viruses, only the retroviruses human immunodeficiency virus (HIV) and human T-cell lymphotropic virus (HTLV)-1 have been convincingly shown to trigger PM, which is mediated by nonviral-specific, cytotoxic CD8+ cells. The treatment of inflammatory myopathies remains empirical. Many patients respond to steroids to some degree and for some period of time. Azathioprine, methotrexate, cyclosporine, cyclophosphamide, and plasmapheresis can be of mild to moderate benefit. High-dose intravenous immunoglobulin (IVIg) is a promising therapeutic modality for some patients resistant to therapies. In a controlled study, IVIg was effective in DM not only in improving the clinical symptoms but also in reversing the underlying immunopathology. The role of IVIg in PM and IBM is under study in control trials.

Inhibition of complement-mediated red cell lysis by immunoglobulins is dependent on the IG isotype and its C1 binding properties

We have investigated the effect on complement activation of human immunoglobulins (Ig) using several therapeutic Ig preparations including two for intravenous use (IVIG), and various purified myeloma proteins. Ig inhibited lysis in a dose-dependent manner in the classical pathway assay whereas no alternative pathway inhibition was observed. The Fc part of the molecule was responsible for all the inhibitory effect. Purified IgG3 myeloma proteins were potent inhibitors whereas IgG1 inhibited to a lesser extent and IgG2 and IgG4 did not inhibit at all. Inhibition was obtained both when Ig was added to the solution and when it was coated onto a solid matrix. Analysis of the soluble and solid phase Ig after incubation revealed binding of C1q and activated C4 and C3 to the isotypes which inhibited lysis. Using selectively depleted sera and reconstitution with their respective purified components, efficient inhibition of lysis was seen when Ig was added prior to serum (C1), some inhibition was seen at the C4 level, whereas no effect was seen when Ig was added at the C9 level. We conclude that the complement-modulatory effect of Ig in vitro is isotype specific and dependent mainly on competitive C1 binding by the Ig molecule in the absence of antigen.

Laboratory evaluation of the inflammatory myopathies

The laboratory plays an important role in the diagnosis, evaluation, and classification of the heterogeneous group of diseases known as the IIM, which are characterized by chronic muscle inflammation. Serial measurements of the levels of muscle-derived enzymes in serum are the traditional laboratory studies used to follow the clinical course of patients with IIM, although other laboratory tests can also be useful in assessing myositis disease activity. Several markers of immune system activation, including cytokines and lymphocyte markers, show promise as possibly more sensitive measures of myositis disease activity. Discovery of a unique group of MSAs over the past decade has provided an immunologic basis for defining relatively homogeneous subsets of patients who share similar clinical features, disease courses, and responses to therapy. Future investigations of novel immunologic activation markers, as well as the cloning and expression of target autoantigens of the MSAs, should allow better diagnostic assays, enhanced prognosis, and a better understanding of the pathogenesis of these disorders.

High-dose intravenous immunoglobulin exerts its beneficial effect in patients with dermatomyositis by blocking endomysial deposition of activated complement fragments

In patients with dermatomyositis (DM) the earliest lesion is microvasculopathy mediated by deposition of C5b-C9 membranolytic attack complex (MAC) on intramuscular capillaries. This leads sequentially to muscle ischemia, necrosis of muscle fibers, and muscle weakness. High-dose intravenous immunoglobulin (IVIG), which can modulate complement-dependent tissue damage in animal models, has been shown to be effective in the treatment of patients with DM. We used an in vitro C3 uptake assay to examine 55 coded sera from 13 patients with DM and 5 patients with other non-complement-mediated neuromuscular diseases, before and after treatment with IVIG or placebo. Patients with active DM had a significantly higher baseline C3 uptake compared with the others (geometric mean 12,190 vs 3,090 cpm). Post-IVIG but not post-placebo sera inhibited the C3 uptake, without depleting the complement components, by 70.6-93.4%. The maximum inhibition of C3 uptake occurred within hours after IVIG infusion, started to rebound 2 d later, and reached pretreatment levels after 30 d. The serum levels of SC5b-9 complex production were high at baseline but normalized after IVIG therapy. Repeat biopsies from muscles of improved patients showed disappearance of C3b NEO and MAC deposits from the endomysial capillaries and restoration of the capillary network. We conclude that IVIG exerts its beneficial clinical effect by intercepting the assembly and deposition of MAC on the endomysial capillaries through the formation of complexes between the infused immunoglobulins and C3b, thereby preventing the incorporation of activated C3 molecules into C5 convertase. These findings provide the first serological and in situ evidence that IVIG modulates complement attack in a human disease.

The immunobiology of muscle

Skeletal muscle can be both the site and target of immune reactions. Here, Reinhard Hohlfeld and Andrew Engel consider the role of muscle as an immunological microenvironment and discuss the immunological properties of human muscle cells. Furthermore, they provide a brief overview of autoimmune diseases of muscle and of other conditions in which intramuscular immune reactions play a role. Finally, they discuss the immunological problems of novel gene therapies that rely on muscle cells as vehicles for gene transfer.

Immunohistochemical analysis of perforin and granzyme A in inflammatory myopathies

Perforin (PF) and granzyme A (GA) are candidates suspected of being cytolytic proteins of the granules of cytotoxic T lymphocytes (CTLs) and natural killer (NK) cells. We analysed PF and GA in muscles from patients with inflammatory myopathies. Five cases of polymyositis (PM), two cases of inclusion body myositis (IBM), and five cases of dermatomyositis (DM) were studied immunohistochemically using anti-PF and GA antibodies raised against each synthetic peptide of human PF and mouse GA, together with a panel of monoclonal antibodies reactive for lymphocyte subsets. In PM and IBM, PF positive cells were colocalized with GA positive cells and occasionally invaded into the non-necrotic muscle fibres. The percentage of PF positive cells among the endomysial CD8 positive cell population was 9.9% (PM) and 12.5% (IBM), and the majority of the endomysial CD8 positive cells were alpha/beta T cells. In contrast, in DM, both PF and GA positive cells were very few in all cases. Only few inflammatory cells were CD16+ or CD57+ NK cells among these diseases. Our results suggest that PF and GA are secreted mainly from alpha/beta T cells, and may play a key role in muscle fibre damage in at least some PM and IBM, but not in DM.

Plasma exchange and intravenous immunoglobulin treatment of neuromuscular disease

Removal of immunoglobulin by plasma exchange and administration of immunoglobulin by intravenous infusion each improve selected neuromuscular diseases. Both treatments are expensive and relatively brief in their duration of action, but they benefit both self-limited neuromuscular diseases such as the Guillain-Barré syndrome and acute exacerbations of more chronic neuromuscular diseases including myasthenia gravis and chronic inflammatory demyelinating polyneuropathy. It is likely that plasma exchange acts by removing pathogenic antibodies. The mechanism by which intravenous immunoglobulin acts is less clear. Possibilities include (1) antiidiotypic antibody effect, (2) complement absorption, (3) downregulation of immunoglobulin production, (4) receptor blockade, (5) virus neutralization, (6) enhancement of suppressor cells, and (7) inhibition of lymphocyte proliferation. Although plasma exchange and intravenous immunoglobulin have major side effects, severe reactions are uncommon with plasma exchange and rare with intravenous immunoglobulin. Because of their low incidence of life-threatening complications, both treatments have major appeal to clinicians. Because of their brief action and high cost as well as the uncertainty as to whether either or both should be employed, their role in the therapeutic armamentarium of the neurologist requires further study.

[Vascular manifestations of dermatomyositis and polymyositis. Clinical, capillaroscopic and histological aspects]

Polymyositis is characterized by a T-cell-mediated and MHC-I-restricted cytotoxic process, whereas dermatomyositis is a primitively vascular disease with microangiopathy mediated by the complement C5b-9 membranolytic attack complex. We have tried to estimate the frequency of vascular abnormalities in polymyositis as defined by Bohan and Peter. We have retrospectively studied 17 patients with dermatomyositis and 15 patients with polymyositis. Vascular abnormalities have been defined by clinical, capillaroscopic and histologic (muscle biopsy and minor salivary glands biopsy) features. After clinical features, 5/17 dermatomyositis had a Raynaud's phenomenon, against 6/15 polymyositis. Digital necrosis has been observed for 2/17 dermatomyositis and 2/15 polymyositis. In capillaroscopy, 14/17 dermatomyositis had a microangiopathy with or no enlarged capillary loops, against 7/15 polymyositis. None of these polymyositis had enlarged capillary loops. The muscle biopsy showed a predominantly perivascular or perimysial inflammatory infiltrate (vascular process) for 10/16 dermatomyositis against 4/13 polymyositis; a perifascicular atrophy for 3/16 dermatomyositis against 2/13 polymyositis. The histological study of minor salivary glands, showed vascular lesions for 2/11 dermatomyositis and for 1/8 polymyositis. Finally, Bohan and Peter's classification is now inadequate to distinguish between dermatomyositis and polymyositis. Indeed, some dermatomyositis sine dermatitis, may exist and be recognized by their vascular features. To distinguish between dermatomyositis and polymyositis is important, to evaluate the risk of cancer which is more frequent in dermatomyositis.

A controlled trial of high-dose intravenous immune globulin infusions as treatment for dermatomyositis

BACKGROUND

Dermatomyositis is a clinically distinct myopathy characterized by rash and a complement-mediated microangiopathy that results in the destruction of muscle fibers. In some patients the condition becomes resistant to therapy and causes severe physical disabilities.

METHODS

We conducted a double-blind, placebo-controlled study of 15 patients (age, 18 to 55 years) with biopsy-proved, treatment-resistant dermatomyositis. The patients continued to receive prednisone (mean daily dose, 25 mg) and were randomly assigned to receive one infusion of immune globulin (2 g per kilogram of body weight) or placebo per month for three months, with the option of crossing over to the alternative therapy for three more months. Clinical response was gauged by assessing muscle strength, neuromuscular symptoms, and changes in the rash. Changes in immune-mediated muscle abnormalities were determined by repeated muscle biopsies.

RESULTS

The eight patients assigned to immune globulin had a significant improvement in sores of muscle strength (P < 0.018) and neuromuscular symptoms (P < 0.035), whereas the seven patients assigned to placebo did not. With crossovers a total of 12 patients received immune globulin. Of these, nine with severe disabilities had a major improvement to nearly normal function. Their mean muscle-strength scores increased from 74.5 to 84.7, and their neuromuscular symptoms improved. Two of the other three patients had mild improvement, and one had no change in his condition. Of 11 placebo-treated patients, none had a major improvement, 3 had mild improvement, 3 had no change in their condition, and 5 had worsening of their condition. Repeated biopsies in five patients of muscles whose strength improved to almost normal showed an increase in muscle-fiber diameter (P < 0.04), an increase in the number and a decrease in the diameter of capillaries (P < 0.01), resolution of complement deposits on capillaries, and a reduction in the expression of intercellular adhesion molecule 1 and major-histocompatibility-complex class I antigens.

CONCLUSIONS

High-dose intravenous immune globulin is a safe and effective treatment for refractory dermatomyositis.

Soluble terminal complement components in human myasthenia gravis

The loss of membrane acetylcholine receptor (AChR) leading to muscle weakness and impaired neuromuscular junction (NMJ) transmission in human myasthenia gravis (MG) is in part due to complement mediated muscle membrane damage. This has been supported by the histologic finding of C9 at the NMJ in human MG. We evaluated for evidence of terminal complement components in plasma by using an ELISA for SC5b-9 in 42 separate plasma samples from 31 patients with MG and from healthy controls. Abnormal elevations of SC5b-9 was found in 18 of 31 patients (58%) at one or more time points when plotted on a standard positive dilution curve. Multiple samples were available from 8 patients over time. Clinical deterioration in some, but not all, was accompanied by an increase in SC5b-9 values. There was no clear distinction in the group as a whole between MG severity or AChR antibody levels and SC5b-9 values. This supports the potential role of complement-mediated muscle membrane damage in the pathogenesis of human MG, but also demonstrates that plasma levels as measured by ELISA do not always correlate with disease activity.

Humoral immunity in polymyositis/dermatomyositis

Autoantibodies are found in most patients with polymyositis (PM) or dermatomyositis (DM) and 35-40% of these patients have myositis-specific antibodies. Twenty-five to thirty percent have anti-aminoacyl-tRNA synthetases, of which anti-Jo-1, directed at histidyl-tRNA synthetase, is by far the most common. Patients with anti-synthetases have a high frequency of myositis, interstitial lung disease, Raynaud's phenomenon, and other features constituting an "anti-synthetase syndrome." Anti-synthetases tend to react with conformational epitopes and to inhibit enzymatic activity, suggesting reaction with conserved regions. Sera with antibodies to alanyl-tRNA synthetase (anti-PL-12) also have antibodies to tRNA(ala), whereas most sera with other anti-synthetases do not react directly with tRNA. Production of the antibodies appears to be antigen-driven, and is influenced by HLA genes, although an initiating factor, possibly a viral infection, may be important. Antibodies to other cytoplasmic antigens, most notably the signal recognition particle (anti-SRP), are seen in a small percentage of patients. Patients with anti-SRP do not tend to develop the anti-synthetase syndrome, but may have very severe disease. Antibodies to the nuclear antigen Mi-2 are also specific for myositis, and are strongly associated with DM. Several autoantibodies, including anti-PM-Scl, anti-Ku, and anti-U1 and U2 RNP, have been associated with scleroderma-PM overlap. The role of humoral immunity in the myositis of PM and DM has not yet been clarified. Capillary loss and ischemic damage are important in DM, and seem to be mediated by humoral mechanisms, whereas cell-mediated attack on muscle fibers is important in PM. The mechanism of skin injury in cutaneous lesions is not known, but antibody deposition is inconsistent and uncommon. Whether the myositis-specific antibodies are involved in disease pathogenesis is not yet known, although there is no direct evidence for this. An understanding of the reasons for production of these antibodies, however, should provide insight into the etiology and pathogenesis of PM and DM.

Microvascular changes in skeletal muscle in idiopathic inflammatory myopathy

Open deltoid muscle biopsy specimens from patients with idiopathic adult dermatomyositis, paraneoplastic dermatomyositis, childhood dermatomyositis, and idiopathic polymyositis, and from control patients were studied. Qualitative and morphometric capillary analysis by phase and electron microscopy was carried out. In the morphologic analysis the most striking difference was the presence of capillary damage and a higher capillary depletion in dermatomyositis as well as a higher capillary density in polymyositis. By electron microscopy, capillaries from patients with dermatomyositis showed mainly microtubuloreticular structures, loss of endothelial plasma membranes, and the appearance of abnormal cytoplasmic organelles. In contrast, capillaries from patients with polymyositis exhibited only minimal changes. By morphometric analysis, muscle capillaries in dermatomyositis had a significantly higher mean endothelial thickness than those in polymyositis. Finally, a significant topographic association between capillary damage and muscle fiber changes was observed only in patients with dermatomyositis. On the other hand, paraneoplastic dermatomyositis showed fewer structural and morphometric capillary changes than the other forms of dermatomyositis. We conclude that dermatomyositis is characterized by microvascular alterations that are absent in polymyositis. The topographic proximity of capillary changes to muscle fiber injury suggests that capillary damage may play a role in the pathogenesis of the muscle lesions observed in patients with dermatomyositis.

Immunointervention with cyclosporin A in autoimmune neurological disorders

Cyclosporin A has proven a remarkably effective compound in suppressing disease activity in a number of animal models of autoimmune neurological disorders. During the last decade a number of controlled clinical trials have been carried out in human neurological disorders which are considered to be immune-mediated. The results of those trials are reviewed.

Efficacy of intravenous gammaglobulin therapy in chronic refractory polymyositis and dermatomyositis: an open study with 20 adult patients

PURPOSE

Polymyositis and dermatomyositis are inflammatory muscular diseases of unknown cause. Many interventions are available to treat patients with these conditions including corticosteroids, immunosuppressive drugs, plasmapheresis, and total body irradiation. However, these therapies are not always effective, and they may be associated with certain serious side effects. An attempt was made to evaluate the efficacy of polyvalent intravenous immunoglobulin (IVIG) in patients with polymyositis or dermatomyositis refractory to traditional treatment.

PATIENTS AND METHODS

Twenty patients (16 women and 4 men; mean age 43 [16 SD] years), 14 with chronic refractory polymyositis and six with dermatomyositis, received high doses of IVIG because of the failure of traditional treatments (prednisone [19], methotrexate [10], azathioprine [6], cyclophosphamide [3], cyclosporine [3], chlorambucil [1], plasmapheresis [8], lymphopheresis [1], and total body irradiation [1]). In one patient with positive results on picornavirus serologic testing, IVIG was the first treatment choice. IVIG therapy was given with prednisone in 15 patients, with methotrexate in six patients, and with plasmapheresis in one patient. There were no changes in treatment in the 2 months before the introduction of IVIG therapy and no increases in dose during this treatment. Preparations of polyvalent human intravenous gammaglobulins with increased intact immunoglobulin G were used. Thirteen patients received 1 g/kg daily for 2 days each month, and seven patients received 0.4 g/kg daily for 5 days each month. The mean duration of treatment was 4 months.

RESULTS

Clinical assessment, which consisted of the measurement of proximal muscle power, and biochemical studies were carried out before each treatment period. Significant clinical improvement was noted in 15 of the 20 patients. Mean muscle power estimated for the 20 patients before and after IVIG therapy was statistically significantly reduced (p less than 0.01). Eighteen patients showed biochemical improvement, and two patients with normal initial serum creatine kinase levels showed clinical improvement. Mean creatine kinase levels for the 20 patients during IVIG therapy showed a statistically significant decrease from the first IVIG perfusions (p less than 0.01). Side effects of IVIG therapy were noted in four patients; however, these effects were mild. During IVIG therapy, steroid doses were significantly reduced from the second or the third IVIG infusion (p less than 0.05).

CONCLUSION

IVIG is an efficacious new therapy for polymyositis and dermatomyositis and should play a role in the treatment of these diseases, replacing or reducing steroid and immunosuppressive medications.

Coculture with autologous myotubes of cytotoxic T cells isolated from muscle in inflammatory myopathies

T-cell lines were expanded from muscle of 10 patients with polymyositis, 5 with inclusion body myositis, 5 with dermatomyositis, and 5 with other muscle diseases. All cell lines uniformly expressed T-cell antigens, but not natural killer cell or B-cell antigens. The proportion of helper (CD4+) and cytotoxic (CD8+) T cells in the expanded lines was variable and showed no correlation with the diagnosis. Sixteen cell lines (6 polymyositis, 4 inclusion body myositis, 5 dermatomyositis, 1 other muscle disease) consisted predominantly of CD8+ T cells. None of these lines displayed natural killer-like cytotoxicity but all were capable of lectin-dependent cytotoxicity. Three of 6 polymyositis, 1 of 4 inclusion body myositis, and 1 of 5 dermatomyositis lines showed low but statistically significant cytotoxicity against autologous myotubes (6 to 27% specific 51Cr release; effector-target ratio, 20:1). The results demonstrate that functionally competent cytotoxic T cells can be expanded from muscle affected by inflammatory myopathies and are consistent with the hypothesis that some cytotoxic T cells recognize an autoantigen on myotubes. Further studies of this experimental system may define the molecular mechanism of T cell-mediated muscle fiber injury and may help to identify the relevant antigens.

Lymphocyte activation markers in idiopathic myositis: changes with disease activity and differences among clinical and autoantibody subgroups

We studied the immunologic correlates of disease activity and differences among subgroups of patients with idiopathic inflammatory myopathy by analysing phenotypic and activation marker expression on peripheral blood mononuclear cells (PBMC). Compared with controls, myositis patients with clinically active disease (n = 51) had significantly lower proportions of CD8+ cells and higher proportions of PBMC that expressed DR, CD3- DR, CD14- DR, interleukin-2 receptors, and the late T cell activation markers CD26 and TLiSA1. TLiSA1 expression, a marker for cytotoxic differentiation, correlated significantly with both clinical activity indices and serum levels of muscle-associated enzymes. In serial studies of seven patients, the proportion of PBMC expressing MHC class II antigen and late T cell activation markers decreased as myositis disease activity decreased, independent of type of therapy. Among the clinical subgroups, polymyositis (n = 21) and inclusion body myositis (n = 11) were virtually indistinguishable; dermatomyositis patients (n = 19) showed decreased proportions of CD3+DR+ and TLiSA1+ cells, and increased proportions of CD20+ and CD20+DR+ cells compared with the other two groups. Patients with autoantibodies to histidyl-tRNA synthetase (Jo-1 antigen, n = 11) had significantly lower proportions of CD3+ and CD4+ cells, lower CD4/CD8 ratios, and higher proportions of CD+ cells expressing CD20, compared with patients without anti-Jo-1 antibodies. These findings support the concept that activated lymphocytes, especially cells undergoing anamnestic responses and cytotoxic differentiation, are important in the pathogenesis of idiopathic myositis. Moreover, taken together with other studies, these data suggest that groups of patients segregated by clinical or autoantibody status have different mechanisms of systemic immune activation and immunopathology.

Antibody to signal recognition particle in polymyositis

Using immunoprecipitation, we identified 13 patients with antibodies to the signal recognition particle (SRP) from a collection of sera representing 265 polymyositis/dermatomyositis (PM/DM) patients. Antibody reactivity with SRP was confirmed by enzyme-linked immunosorbent assay and immunoprecipitation with isolated dog pancreas SRP. The antibody was present in the serum of 4% of PM/DM patients, and 18% of PM/DM patients with anticytoplasmic antibodies other than anti-Jo-1, but not in patients with other conditions who had anticytoplasmic antibodies. Anti-SRP was associated with classic adult PM, and some of these cases were unusually severe and/or of rapid onset; it was not found in patients with overlap syndromes or with DM involvement. Unlike patients with antibodies to aminoacyl-transfer RNA synthetases, patients with anti-SRP had a low frequency of pulmonary fibrosis, as well as of arthritis and Raynaud's phenomenon. Anti-SRP antibodies may serve as a marker for a second, distinct subgroup of adult PM.

Microvascular changes in early and advanced dermatomyositis: a quantitative study

In adult dermatomyositis 10 muscle specimens with no or minimal histological alterations were compared with 7 that showed typical alterations. Five specimens from patients with inclusion body myositis, 5 from patients with polymyositis, and 8 from normal subjects served as controls. Vascular endothelium, visualized with the lectin Ulex europaeus agglutinin I, and complement membrane attack complex were demonstrated in the same cryostat sections by paired immunofluorescence. Large randomly selected fields were analyzed to determine the number of capillaries per square millimeter of fiber area (capillary density), per 1,000-microns 2 area of each muscle fiber (capillary index), and in 100 x 100-microns grid squares. In dermatomyositis specimens with minimal structural alterations there was focal capillary depletion, the capillary density was significantly reduced, and the frequency distributions of the capillary index and grid count were shifted to the left. In advanced dermatomyositis specimens, the findings were similar but more severe. In both kinds of specimens, clusters of capillaries reacted for complement membrane attack complex. The 2 patients with the highest proportion of vessels positive for membrane attack complex had a fulminant and fatal course. In polymyositis and inclusion body myositis specimens, the capillaries had a normal overall density and none reacted for membrane attack complex. The findings imply that the capillaries are an early and specific target of the disease process in dermatomyositis.

Relationship between capillary and muscle damage in dermatomyositis

To assess the pathogenetic importance of capillary damage and its relationship with degenerating muscle fibers in dermatomyositis (DM), an electron microscope study of eight muscle biopsy specimens (adult and juvenile forms) and seven muscle specimens from patients with other neuromuscular diseases was conducted. There was a 49% reduction of capillaries in the muscle specimens of DM patients. Capillary damage also was more frequent in the DM group than in control group (p less than 0.001). We found a striking relation between capillary and muscle damage in the DM group (p less than 0.002) but not in the control group. The diagnostic value of undulating tubules within endothelial cells is also discussed.

Clinical manifestations in patients with antibody to PL-12 antigen (alanyl-tRNA synthetase)

PURPOSE

Anti-PL-12 antibody is directed at the enzyme alanyl-tRNA synthetase (ARS). Studies have clearly associated anti-Jo-1, also directed at an aminoacyl-tRNA synthetase (histidyl-tRNA synthetase), with a subgroup of myositis marked by a high frequency of interstitial lung disease (ILD) and arthritis. A similar syndrome has been reported in patients with antibodies to PL-12, but few patients have been studied. We describe the clinical manifestations in a new series of patients with antibody to PL-12.

PATIENTS AND METHODS

Sera from patients with polymyositis and sera found to contain anticytoplasmic antibodies were screened for antibody to PL-12 by testing for inhibition of ARS enzymatic activity by serum, and by immunoprecipitation.

RESULTS

Nine sera inhibited ARS. These nine plus two additional sera with anticytoplasmic antibodies immunoprecipitated an identical pattern of tRNAs and a polypeptide of 110 kd. Of the 10 patients that could be evaluated, eight had some evidence of myositis, including six that satisfied the criteria for myositis. Three of these six, all with dermatomyositis, had severe muscle involvement. Eight of the 10 patients had radiographic evidence of pulmonary fibrosis, and seven of the eight had clinical pulmonary impairment, including four with clinically severe ILD. Joint manifestations were found in five patients, and arthritis was the only clinical problem in one patient.

CONCLUSION

We conclude that anti-PL-12, like anti-Jo-1 and anti-PL-7, was frequently associated with the "Jo-1 syndrome" of myositis with ILD. ILD was a major clinical problem in this group of patients.

Early ultrastructural alterations in adult dermatomyositis. Capillary abnormalities precede other structural changes in muscle

In 6 adults with dermatomyositis, minimally weak or nonweak muscles that showed inconclusive light-microscopic alterations were examined by electron microscopy. In all 6 specimens, this revealed pathologic changes in endomysial capillaries. The endothelial cells harbored microtubular inclusions and microvacuoles in all cases; pale swollen endothelial cells were observed in 3 specimens. There were no significant ultrastructural changes in the muscle fibers. In all cases, a small proportion of muscle capillaries were immunoreactive for complement membrane attack complex neoantigens. The findings imply that in adult dermatomyositis capillary injury precedes muscle fiber damage and infiltration by inflammatory cells, and that the microvasculature is an early and specific target of the disease process in muscle.

Complement membrane attack on nucleated cells: resistance, recovery and non-lethal effects

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Consequences of breast irradiation in patients with pre-existing collagen vascular diseases

Exaggerated acute and late effects were observed in three of four women with pre-existing collagen vascular disease (CVD) within 2 years after definitive megavoltage radiation therapy for breast carcinoma. Five women with breast carcinoma, who developed CVD 3 months to 10 years after radiation therapy, had no complications. An abnormally severe reaction was observed during treatment of one patient with discoid lupus. The patient developed moist desquamation that persisted for a month, requiring early termination of treatment. One year after treatment, the patient developed paresthesias in the ipsilateral arm. A planned reduction of the prescribed dose in a second patient with progressive systemic sclerosis did not prevent intense erythema at the end of treatment, followed 14 months later by chest wall necrosis, which eventually required multiple surgeries including chest wall resections. The third patient, who had systemic lupus erythematosis, developed necrosis 2 years after treatment, which progressed over 12 years to osteoradionecrosis of the clavicle, sternum and rib cage. Multiple surgeries to repair the defect were complicated by flap necrosis and pleurocutaneous fistulas. The fourth patient died 6 months after radiotherapy without apparent sequelae. None of the patients had evidence of recurrent carcinoma. A history of collagen vascular disease appears to be a contraindication to breast conservation or for elective irradiation for breast cancer.

Dermatomyositis and malignancy

In summary, it can be stated that: 1. Dermatomyositis is probably associated with an increased incidence of malignancy. 2. Tumor types found seem to roughly approximate the frequencies of those found in the general population. 3. If present, the malignancy can precede, occur concurrently with, or follow the diagnosis of dermatomyositis. 4. Treatment of associated malignancy may or may not have an effect on myositic or cutaneous disease. 5. Dermatomyositis and associated malignancy may share a common pathogenesis resulting from abnormal immune function. 6. Search for malignancy should be carried out on the basis of abnormal findings on history and physical examination or screening laboratory.

Evidence for a novel picornavirus in human dermatomyositis

We prepared RNA probes from cloned segments of human and murine enteroviruses (EVs) for in situ hybridization of skeletal muscle biopsies from patients with dermatomyositis (DM), polymyositis, other inflammatory myopathies, and noninflammatory muscle diseases, and from normal control subjects. A probe derived from Theiler's murine encephalomyelitis virus (TMEV) detected viral RNA within mononuclear cells of the interstitial connective tissue in 3 of 5 patients with adult-onset DM. None of these patients showed positive hybridization to probes derived from human EVs (poliovirus type 1 and Coxsackie virus B3) applied to subjacent sections of the same biopsies. The remaining 2 adult DM patients, 4 patients with childhood-onset DM, and 24 non-DM patients did not react with either TMEV or human enterovirus probes. Histochemical stains for esterase and immunoperoxidase stains for Mac-1 antigen in the 3 DM patients who reacted positively revealed positive cells in the same distribution as, but in far greater number than, those positive by in situ hybridization. Immunoperoxidase staining for HLA-DR antigens revealed positive cells in the same distribution and number as were seen with the TMEV probe. We conclude that an EV-like agent, more closely related to TMEV than to human EVs, may be associated with DM and that this agent is probably localized within muscle macrophages that express class II major histocompatibility complex antigens.

Polymyositis-dermatomyositis: a clinical review

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