Pathogenesis of idiopathic inflammatory myopathies

The idiopathic inflammatory myopathies, myositis, are characterized by a chronic course with decreased muscle endurance and by infiltrates of T lymphocytes and macrophages in muscle tissue. Treatment with immunosuppressives rarely leads to recovery of muscle function, despite abolishment of inflammatory cell infiltrates in muscle tissue. Therefore, other mechanisms than immune-mediated muscle fiber damage are likely to contribute to the pathogenesis. One such non-immune-mediated muscle dysfunction could be caused by a disturbed microcirculation due to capillary loss or to phenotypically changed endothelial cells in the capillaries. These aberrations may affect the micro-environment of muscle tissue and lead to local tissue hypoxia with development of a secondary metabolic myopathy. Another possible non-immune-mediated mechanism leading to muscle dysfunction is the newly identified endoplasmatic reticulum (ER) stress response in myositis. The ER stress response is thought to be a consequence of the up-regulation of major histocompatibility complex class I in muscle fibers. These newly identified molecular pathways could play a major role in the pathogenesis of myositis and could be important targets in the development of new therapies.

Anti-signal recognition particle autoantibodies: marker of a necrotising myopathy

OBJECTIVE

To elucidate the clinical importance of the anti-signal recognition particle (SRP) autoantibody in patients with myositis.

METHODS

Retrospective systematic assessment of the clinical, laboratory and histological characteristics of 23 anti-SRP-positive patients from six European centres. Data were compared with a large group of anti-SRP-negative patients with myositis published previously.

RESULTS

Clinically, patients with anti-SRP autoantibodies often had a severe symmetric proximal muscle weakness resulting in marked disability, dysphagia and highly elevated levels of serum creatine kinase. Three patients had typical dermatomyositis rashes. The disease was associated with the occurrence of extramuscular signs and symptoms including interstitial lung disease. No association was found with an increased risk of cardiac involvement, and the disease carried a reasonably favourable prognosis with most patients responding to treatment. None of the patients had the typical histological features of myositis. Most muscle biopsy specimens showed the presence of necrotic muscle fibres and no inflammatory infiltrates.

CONCLUSIONS

Anti-SRP autoantibodies are associated with a syndrome of a necrotising myopathy in the spectrum of immune-mediated myopathies that differs from typical polymyositis. Further studies are needed to elucidate the pathogenesis and to clarify the role of the anti-SRP autoantibodies in this unique disease.

Citrullination is an inflammation-dependent process

OBJECTIVES

To study the presence of citrullinated proteins in inflammatory conditions and in clinically non-affected tissues of controls.

METHODS

Synovial biopsy specimens from 19 patients with rheumatoid arthritis and 10 healthy controls were investigated by immunohistochemistry. Additionally, muscle tissue from 5 patients with polymyositis and from 7 healthy controls, intestinal tissue from macroscopically affected and non-affected areas from 10 patients with inflammatory bowel disease (IBD) and tonsil tissues from 4 chronically inflamed tonsils were studied.

RESULTS

Citrullinated proteins were present in all synovial biopsy specimens from patients with rheumatoid arthritis, whereas only three of 10 healthy synovial biopsy specimens showed scarce amounts of citrullination. Citrullination was also present in all myositis-affected muscles, whereas it was absent in the muscle tissues of controls. All tonsil biopsy specimens studied were positive for citrulline. Even though more frequently detected in the macroscopically affected colonic areas, no marked difference was observed in the pattern or extent of citrullination between the macroscopically affected and non-affected intestinal IBD tissues.

CONCLUSION

Citrullination is present in a wide range of inflammatory tissues, suggesting that this process is inflammation dependent rather than disease dependent.

Clinical characteristics of patients with myositis and autoantibodies to different fragments of the Mi-2 beta antigen

OBJECTIVES

To assess the clinical implications of autoantibodies directed against different parts of the Mi-2 beta autoantigen in patients with myositis.

METHODS

A systematic assessment of the clinical, laboratory, and histological characteristics of 48 anti-Mi-2 positive patients from six European centres was made. Anti-Mi-2 autoantibodies were determined with an ELISA using four overlapping fragments spanning the entire amino acid sequence of the autoantigen. Data were compared with results for a large group of anti-Mi-2 negative patients with myositis published previously.

RESULTS

Anti-Mi-2 autoantibodies were found in dermatomyositis, polymyositis, and inclusion body myositis. In general, myositis with anti-Mi-2 autoantibodies was characterised by relatively mild disease, sometimes accompanied by extra-muscular symptoms, including arthralgia, arthritis, Raynaud's phenomenon, and interstitial lung disease. Cardiac disease was not seen, and treatment response was fair. No differences were found between patients with autoantibodies to different fragments of the Mi-2 beta antigen, except for a potentially increased risk of cancer in patients with antibodies directed to the N-terminal fragment of the autoantigen.

CONCLUSIONS

Anti-Mi-2 autoantibodies are not a marker of a specific subtype of myositis. No significant differences between patients with autoantibodies to different fragments of the Mi-2 beta autoantigen are found, with the possible exception of an increased risk of cancer in patients with antibodies to the N-terminal fragment.

Endothelial cell activation and neovascularization are prominent in dermatomyositis

Background

While vascular and immune abnormalities are common in juvenile and adult dermatomyositis (DM), the molecular changes that contribute to these abnormalities are not clear. Therefore, we investigated pathways that facilitate new blood vessel formation and dendritic cell migration in dermatomyositis.

Methods

Muscle biopsies from subjects with DM (9 children and 6 adults) and non-myositis controls (6 children and 7 adults) were investigated by immunohistochemistry using antibodies that recognize existing (anti-CD146) and newly formed blood vessels (anti-αVβ3) and mature dendritic cells (anti-DC-LAMP). Blood vessel quantification was performed by digitalized image analysis. Additional muscle biopsies from subjects with adult DM and non-myositis controls were used for global gene expression profiling experiments.

Results

A significant increase in neovascularization was found in muscle biopsies of DM patients; neovascularization (αVβ3 positive capillaries and vessels per muscle fiber) was much higher in juvenile than in adult DM patients (control vs juvenile DM: Mean ± SE: 0.06 ± 0.01 vs 0.6 ± 0.05; p < 0.0001 and control vs adult DM: Mean ± SE: 0.60 ± 0.1 vs 0.75 ± 0.1; p = 0.051). Gene expression analysis demonstrated that genes that participate not only in angiogenesis but also in leukocyte trafficking and the complement cascade were highly up regulated in DM muscle in comparison to age matched controls. DC-LAMP positive dendritic cells were highly enriched at perivascular inflammatory sites in juvenile and adult DM patients along with molecules that facilitate dendritic cell transmigration and reverse transmigration (CD142 and CD31).

Conclusion

These results suggest active neovascularization and endothelial cell activation in both juvenile and adult DM. It is likely that close association of monocytes with endothelial cells initiate rapid dendritic cell maturation and an autoimmune response in DM.

Restricted T cell receptor BV gene usage in the lungs and muscles of patients with idiopathic inflammatory myopathies

OBJECTIVE

To investigate T cell receptor (TCR) expression in 3 different compartments that could be involved in patients with myositis: muscle, lung, and peripheral blood.

METHODS

Nine patients with polymyositis (PM), dermatomyositis, or inclusion body myositis underwent bronchoscopy and bronchoalveolar lavage (BAL) as well as muscle biopsy and blood sampling. A panel of 19 monoclonal antibodies specific for TCR V(beta) (BV) and V(alpha) (AV) were used to characterize the TCR profile in CD4(+) and CD8(+) T cell populations in BAL fluid and peripheral blood by flow cytometry. Muscle biopsy tissues were analyzed by immunohistochemistry. Patients were also typed for HLA-DRB1 and DRB3 alleles.

RESULTS

A total of 17 T cell expansions were detected in BAL fluid, 6 in the CD4(+) T cell population and 11 in the CD8(+) T cell population. Four T cell expansions were detected in peripheral blood. A selective TCR V usage was found in muscle. Two PM patients, both of whom had BAL fluid BV3(+) T cell expansions in the CD4 population and in whom BV3 was also a prominent TCR V segment in muscle tissue, shared the HLA-DRB1*03 allele. These 2 patients were the only ones who were positive for anti-Jo-1 antibody.

CONCLUSION

We found a restricted accumulation of T lymphocytes expressing selected TCR V-gene segments in the target organ compartments (i.e., lung and muscle). The occurrence of shared TCR gene segment usage in muscle and lungs could suggest common target antigens in these organs.

Functional index-2: Validity and reliability of a disease-specific measure of impairment in patients with polymyositis and dermatomyositis

OBJECTIVE

To revise the content of the Functional Index in myositis (FI) and to evaluate measurement properties of a revised FI.

METHODS

Previously performed FI (n = 287) were analyzed for internal redundancy and consistency, and ceiling and floor effects. Content was evaluated and a preliminary revised FI was developed. To evaluate the construct validity of the preliminary revised FI, it was compared with isokinetic measurements of muscular strength and endurance, the Myositis Activities Profile, disease impact on general wellbeing, and creatine phosphokinase levels. Minor adjustments were made and the revised FI was investigated for interrater reliability and intrarater reliability over a 1-week period. After this, some minor, additional adjustments were made leading to the final version, FI-2.

RESULTS

Five tasks were removed from the original FI due to ceiling effects. Performance pace and number of repetitions were modified for the remaining tasks. A moderate correlation (r(s) = 0.58) was found between the shoulder flexion task of the preliminary revised FI and isokinetic measurements of shoulder flexion endurance. Intraclass correlation coefficient (ICC) for interrater reliability of the revised FI varied from 0.86-0.99 with no systematic differences. ICC for intrarater reliability varied from 0.56-0.99 with systematic differences (P < 0.05) between test and retest in 3 of the tasks. The sit-up task was excluded due to low intrarater reliability resulting in the final 7-item FI-2. There was a good correlation between tasks on the right and left side suggesting that the FI-2 could be performed unilaterally.

CONCLUSION

The FI-2 is a valid and reliable outcome measure of impairment for patients with polymyositis or dermatomyositis. It is well tolerated and the unilateral FI-2 requires a maximum of 20 minutes to perform. Further evaluation of sensitivity to change and testing in healthy individuals needs to be conducted.

Interstitial lung disease in polymyositis and dermatomyositis

PURPOSE OF REVIEW

The purpose of this review is to discuss current concepts regarding management of interstitial lung disease in polymyositis and dermatomyositis.

RECENT FINDINGS

Interstitial lung disease seems to be a more frequent manifestation in patients with polymyositis and dermatomyositis than previously reported. Modern technology, including high-resolution computerized tomography in combination with pulmonary function tests provides sensitive tools to detect early signs of interstitial lung disease. By systematic use of these investigations in newly diagnosed polymyositis and dermatomyositis, up to two thirds of patients were discovered to have signs of interstitial lung disease in a recent study. Clinical symptoms such as cough and dyspnea may not be sensitive enough to detect interstitial lung disease. Awareness of this complication in patients with myositis is important, because early diagnosis and management of interstitial lung disease may prevent development of chronic pulmonary fibrosis and thereby prolong patient survival and improve quality of life. Treatment recommendations of interstitial lung disease in polymyositis and dermatomyositis are still limited by absence of controlled trials and could only be based on experiences from small case series and case reports. At least some patients with interstitial lung disease improve with immunosuppressive treatment, but data are limited, and longitudinal studies are needed.

SUMMARY

Interstitial lung disease seems to be a common manifestation in patients with polymyositis and dermatomyositis already at diagnosis of the muscle disease. When present, interstitial lung disease has a major effect on morbidity and mortality and should be looked for in these patients using high-resolution computerized tomography and pulmonary function tests early in the disease course, because immunosuppressive treatment may change the course of the lung disease.

The prognosis of mixed connective tissue disease

The prognosis for patients who have mixed connective tissue disease (MCTD) varies from a benign course to severe progressive disease. In approximately one third of patients the clinical symptoms go into long-term remission and the anti-U1 small nuclear ribonucleoprotein antibodies disappear. One third of patients have a severe, progressive disease course. Persistent morbidity often is attributable to arthritis, easy fatiguability, and dyspnea on exertion. The most severe clinical manifestation is pulmonary hypertension which contributes to premature death in patients who have MCTD. Pulmonary hypertension is associated with proliferative vascular abnormalities that involve small pulmonary vessels, rather than interstitial lung disease.

The role of exercise in the rehabilitation of idiopathic inflammatory myopathies

PURPOSE OF REVIEW

The objective of this review is to provide an update on exercise and clinical assessment in the idiopathic inflammatory myopathies.

RECENT FINDINGS

Polymyositis, dermatomyositis and inclusion body myositis are rare conditions with muscle weakness as a common prominent feature. Earlier, these patients were discouraged from active exercise due to a fear of increased muscle inflammation with recommendations to rest, perform range of motion exercises and in some cases, isometric exercises. However, beginning in the 1990s, studies reported reduced disability in patients with chronic polymyositis/dermatomyositis following resistive mild/moderate to intensive muscular training and aerobic endurance training, without signs of increased muscle inflammation. Patients with active, recent onset disease seem to benefit from mild/moderate muscular exercise without signs of increased muscle inflammation. There is no evidence of increased muscle inflammation following exercise in inclusion body myositis. However the beneficial effects are unclear as one study report increased muscle strength, while the other could not achieve impairment reduction.

SUMMARY

Studies evaluating active exercise in IIM support the notion of safety and benefits. However, large multi-center studies are needed to fully establish the safety and benefits of different types of exercise. Data indicate that active exercise, adapted to disease activity and disability should be included in the rehabilitation of patients in all stages of IIM. The newly developed and validated outcome measures for patients with polymyositis and dermatomyositis help assess the effects of interventions on disease activity and disability in clinical trials and in clinical practice. However, there are no sensitive and valid outcome measure for patients with inclusion body myositis.

Lipid peroxidation is enhanced in patients with systemic lupus erythematosus and is associated with arterial and renal disease manifestations

OBJECTIVE

Cardiovascular disease with premature atherosclerosis is common in patients with systemic lupus erythematosus (SLE). We previously identified elevated levels of oxidized low-density lipoprotein (OxLDL) together with elevated levels of autoantibodies related to OxLDL as risk factors for cardiovascular disease in female patients with SLE. Autoantibodies to OxLDL are common in SLE and cross-react with anticardiolipin antibodies (aCL). We therefore hypothesized that lipid peroxidation is enhanced in patients with SLE in general.

METHODS

One hundred forty-seven female patients with SLE and 60 age- and sex-matched controls were compared. A monoclonal antibody to oxidized phospholipids, EO6, was used to determine oxidation epitopes on LDL. Anti-OxLDL and autoantibodies to malondialdehyde (MDA)-modified LDL, cardiolipin, and oxidized aCL were determined by chemiluminescence technique.

RESULTS

As determined by binding of EO6, patients with SLE had a higher level of oxidized phospholipids on LDL (P = 0.005) compared with controls. The level of OxLDL (e.g., oxidized phospholipid/apolipoprotein B) was associated with arterial disease (P = 0.006) and renal manifestations (P = 0.04). As reported previously, levels of aCL, autoantibodies to OxLDL, and autoantibodies to MDA-modified LDL were enhanced and were closely correlated in SLE. Anticardiolipin antibodies from these SLE patients recognized mainly oxidized forms of cardiolipin, indicating that antigenic epitopes on cardiolipin are related to lipid peroxidation in patients with SLE.

CONCLUSION

In general, patients with SLE (particularly those with cardiovascular disease) had more oxidized epitopes on LDL compared with controls. Furthermore, aCL in these patients recognized epitopes generated during lipid peroxidation. Thus, "neo" self antigens on lipoproteins, generated during oxidation, are present in SLE and may be of importance for the development of premature cardiovascular disease and possibly also for other autoimmune phenomena observed in SLE.

Down-regulation of the aberrant expression of the inflammation mediator high mobility group box chromosomal protein 1 in muscle tissue of patients with polymyositis and dermatomyositis treated with corticosteroids

OBJECTIVE

High mobility group box chromosomal protein 1 (HMGB-1) is an endogenous nuclear protein that can be translocated to the cytoplasm and then released extracellularly. It can induce tumor necrosis factor and interleukin-1 production in myeloid cells. Increased expression of these 2 cytokines has been observed in muscle tissue of patients with polymyositis (PM) and dermatomyositis (DM). The present study was therefore undertaken to investigate how HMGB-1 is expressed in muscle tissue of patients with myositis and, if so, whether such expression is modulated by prednisolone therapy.

METHODS

Muscle biopsy specimens from 5 patients with PM and 4 patients with DM, obtained before and 3-6 months after initiation of prednisolone therapy, were assessed by conventional microscopic evaluation and computerized image analysis, and HMGB-1 expression was investigated by immunohistochemical staining. Muscle biopsy specimens from 7 healthy controls were also studied.

RESULTS

Cytoplasmic HMGB-1 expression was detected in infiltrating rounded mononuclear cells, vascular endothelial cells, and muscle fibers of PM and DM patients. Extracellular staining surrounding the inflammatory cells was also observed. After treatment with high-dose prednisolone, cytoplasmic and extracellular HMGB-1 expression was significantly reduced, coinciding mainly with a decreased number of infiltrating inflammatory cells. Cytoplasmic HMGB-1 expression was still evident in endothelial cells and muscle fibers. No HMGB-1 expression was observed in muscle tissue from healthy controls.

CONCLUSION

The cytoplasmic and extracellular distribution of HMGB-1 in muscle tissue may indicate an important role of this proinflammatory molecule in the pathogenesis of PM and DM. Furthermore, our findings indicate that systemically administered high-dose corticosteroids selectively down-regulate aberrant expression of HMGB-1 in mononuclear inflammatory cells in vivo.

Corticosteroids--from an idea to clinical use

Corticosteroids form the basis of treatment in many inflammatory rheumatic diseases, both as systemic treatment and as treatment with local injections to reduce inflammation. In 1948 the first systemic treatment of a patient with a rheumatic disease was given to a woman with severe rheumatoid arthritis (RA); the impressive effect in this patient, and in another 15 patients, was reported by Dr Hench and co-workers in 1949. Systemic corticosteroid treatment was rapidly adopted and used not only for patients with RA but also for those with other rheumatic diseases such as systemic lupus erythematosus-as well as other disorders such as asthma-with a similar positive effect. In the following year, 1950, the Nobel Prize was awarded for the discovery of the structure and biological effects of the adrenal cortex hormones. This open trial was followed by several controlled trials conducted in the UK in which the effects of cortisone were compared with the effects of aspirin in patients with RA-interestingly, without any significant clinical benefit for the cortisone-treated patients. It was not until 1959, in yet another multi-centre trial in Britain, that a significant effect on functional capacity and general well-being was reported after 2 years of treatment with prednisolone, compared to aspirin, in patients with early RA. Despite the dramatic effects that were observed in the severely ill RA patients reported by Hench and co-workers it took 10 years to demonstrate that this effect was superior to the effect of aspirin when the two compounds were compared in controlled trials. Why was this so? One explanation could be in the study designs and the different outcome measures used in the various studies. Perhaps the results in the first comparative studies would have been different if individual response criteria had been used. This is discussed in this chapter.

Interstitial lung disease, a common manifestation of newly diagnosed polymyositis and dermatomyositis

OBJECTIVES

To estimate the prevalence and predictors of interstitial lung disease in newly diagnosed polymyositis and dermatomyositis.

METHODS

A prospective study in which consecutive patients with newly diagnosed poly- and dermatomyositis, regardless of clinical symptoms of pulmonary disease, were investigated with chest x ray, high resolution computed tomography (HRCT), pulmonary function tests, and biochemical and autoantibody analysis. Patients with inclusion body myositis, malignancy, other defined inflammatory connective tissue diseases (CTDs), or antibody profile indicating other CTDs were excluded.

RESULTS

Between March 1998 and September 2000, 26 new cases of poly- or dermatomyositis were diagnosed; 17 of those patients were included in the study. Interstitial lung disease (ILD), defined as radiological signs on chest x ray examination/HRCT or restrictive ventilatory defect, were found in 11 (65%) patients and were more common in men than in women. Arthritis and occurrence of anti-Jo-1 antibodies were found more often in patients with ILD than in those without. There was no statistically significant association between respiratory symptoms, other serological or laboratory variables and ILD.

CONCLUSIONS

ILD is a common early manifestation in patients with poly- and dermatomyositis and is not always related to clinical symptoms. Chest x ray examination, HRCT, pulmonary function tests, and analysis of anti-Jo-1 antibodies should be included in the initial investigation of patients with myositis regardless of respiratory symptoms.

Leukocytes, cytokines, growth factors and hormones in human skeletal muscle and blood after uphill or downhill running

Muscular adaptation to physical exercise has previously been described as a repair process following tissue damage. Recently, evidence has been published to question this hypothesis. The purpose of this study was to investigate inflammatory processes in human skeletal muscle and epimysium after acute physical exercise with large eccentric components. Three groups of subjects (n= 19) performed 45 min treadmill running at either 4 deg (n= 5) or 8 deg (n= 9) downhill or 4 deg uphill (n= 5) and one group served as control (n= 9). One biopsy was taken from each subject 48 h post exercise. Blood samples were taken up to 7 days post exercise. Compared to the control group, none of the markers of inflammation in muscle and epimysium samples was different in any exercised group. Only subjects in the Downhill groups experienced delayed onset of muscle soreness (DOMS) and increased serum creatine kinase activity (CK). The detected levels of immunohistochemical markers for T cells (CD3), granulocytes (CD11b), leukaemia inhibitory factor (LIF) and hypoxia-inducible factor 1beta (HIF-1beta) were greater in epimysium from exercised subjects with DOMS ratings >3 (0-10 scale) compared to exercised subjects without DOMS but not higher than controls. Eccentric physical exercise (downhill running) did not result in skeletal muscle inflammation 48 h post exercise, despite DOMS and increased CK. It is suggested that exercise can induce DOMS by activating inflammatory factors present in the epimysium before exercise. Repeated physical training may alter the content of inflammatory factors in the epimysium and thus reduce DOMS.

International consensus outcome measures for patients with idiopathic inflammatory myopathies. Development and initial validation of myositis activity and damage indices in patients with adult onset disease

OBJECTIVE

To devise new tools to assess activity and damage in patients with idiopathic myopathies (IIM).

METHODS

An international multidisciplinary consensus effort to standardize the conduct and reporting of the myositis clinical trials has been established. Two tools, known as the myositis intention to treat index (MITAX) and the myositis disease activity assessment visual analogue scale (MYOACT), have been developed to capture activity in patients with IIM. In addition, the myositis damage index (MDI) has been devised to assess the extent and severity of damage developing in different organs and systems. These measures have been reviewed by the myositis experts participating in the International Myositis Assessment and Clinical Studies (IMACS) group and have been found to have good face validity and to be comprehensive. The instruments were assessed in two real patient exercises involving patients with adult dermatomyositis and inclusion body myositis.

RESULTS

The reliability of MITAX, MYOACT and MDI, measured by the intraclass correlation coefficient among the physicians, and the inter-rater reliability, as assessed by variation in the physicians' rating of patients, was fair to good for most aspects of the tools. Reliability and inter-rater agreement improved at the second exercise after the participants had completed additional training.

CONCLUSIONS

The MITAX, MYOACT and MDI tools, which are now undergoing validity testing, should enhance the consistency, comprehensiveness and reliability of disease activity and damage assessment in patients with myositis.

International consensus outcome measures for patients with idiopathic inflammatory myopathies. Development and initial validation of myositis activity and damage indices in patients with adult onset disease

OBJECTIVE

To devise new tools to assess activity and damage in patients with idiopathic myopathies (IIM).

METHODS

An international multidisciplinary consensus effort to standardize the conduct and reporting of the myositis clinical trials has been established. Two tools, known as the myositis intention to treat index (MITAX) and the myositis disease activity assessment visual analogue scale (MYOACT), have been developed to capture activity in patients with IIM. In addition, the myositis damage index (MDI) has been devised to assess the extent and severity of damage developing in different organs and systems. These measures have been reviewed by the myositis experts participating in the International Myositis Assessment and Clinical Studies (IMACS) group and have been found to have good face validity and to be comprehensive. The instruments were assessed in two real patient exercises involving patients with adult dermatomyositis and inclusion body myositis.

RESULTS

The reliability of MITAX, MYOACT and MDI, measured by the intraclass correlation coefficient among the physicians, and the inter-rater reliability, as assessed by variation in the physicians' rating of patients, was fair to good for most aspects of the tools. Reliability and inter-rater agreement improved at the second exercise after the participants had completed additional training.

CONCLUSIONS

The MITAX, MYOACT and MDI tools, which are now undergoing validity testing, should enhance the consistency, comprehensiveness and reliability of disease activity and damage assessment in patients with myositis.

Elevated triglycerides and low levels of high-density lipoprotein as markers of disease activity in association with up-regulation of the tumor necrosis factor alpha/tumor necrosis factor receptor system in systemic lupus erythematosus

OBJECTIVE

To investigate how blood lipid levels are related to disease activity, clinical characteristics, and serum levels of tumor necrosis factor alpha (TNF alpha) and its soluble type 1 and 2 receptors, sTNFR1 and sTNFR2, in systemic lupus erythematosus (SLE).

METHODS

Fasting blood samples were obtained from an unselected cohort of SLE patients at Karolinska Hospital (n = 208, mean +/- SD age 45.7 +/- 14.2 years). Disease activity was estimated using the SLE Disease Activity Measure (SLAM). Levels of circulating TNF alpha, sTNFR1, and sTNFR2 were determined by enzyme-linked immunosorbent assay. Blood lipid levels obtained after overnight fasting were analyzed by routine chemistry.

RESULTS

Triglyceride (TG) levels were associated with the SLAM score (r = 0.48, P < 0.0001) and with the activities of TNF alpha (r = 0.29, P = 0.0001), sTNFR1 (r = 0.38, P < 0.0001), and sTNFR2 (r = 0.40, P < 0.0001). High-density lipoprotein (HDL) levels were negatively associated with the SLAM score (r = -0.27, P = 0.0003) and with the activities of TNF alpha (r = -0.15, P = 0.04) and sTNFR2 (r = -0.19, P = 0.01). High levels of TGs, total cholesterol, TNF alpha, sTNFR1, and sTNFR2 all showed close correlations with the presence of nephritis and arterial disease (P < 0.05). In multiple logistic regression models, the TNF alpha activity and TG levels were independent determinants (P = 0.003 for both) of active disease (SLAM score > or =7).

CONCLUSION

Dyslipoproteinemia with high TG/low HDL levels correlates with disease activity in SLE, and enhanced activity in the TNFalpha/sTNFR system seems to be an important underlying factor. Both dyslipoproteinemia and enhanced activity of the TNF alpha system are closely related to cardiovascular and renal manifestations in SLE, and thus both may serve as markers of more severe disease.

CBA/J mice infected with Trypanosoma cruzi: an experimental model for inflammatory myopathies

Idiopathic inflammatory myopathies are inflammatory disorders of unknown origin, characterized by muscle weakness. The aim of our study was to establish and characterize an animal model for chronic inflammatory myopathy which would permit investigations of the role of T-cells in chronic myositis as well as of the mechanisms for muscle weakness in chronic inflammatory muscle disorders. CBA/J mice were infected with the protozoan parasite Trypanosoma cruzi. Immunohistochemistry was used to characterize the distribution and composition of inflammatory infiltrates, and demonstrated a chronic focal inflammation comprised mainly of T-cells and macrophages in infected mice. The inflammatory infiltrates were predominantly found in the endomysium and, to a lesser extent, in perivascular areas. CD8(+) T-cells were found to have invaded nonnecrotic muscle fibers. Degenerating muscle fibers were also found, as well as an increased number of central muscle nuclei. The murine model described in this article may be useful in studying certain aspects of idiopathic inflammatory myopathies such as the role of T-cells in chronic muscle inflammation and chronic myocytotoxicity.

MICA4/HLA-DRB1*04/TNF1 haplotype is associated with mixed connective tissue disease in Swedish patients

In order to investigate major histocompatibility complex (MHC) class I chain-related gene A (MICA), tumor necrosis factor (TNFa), -308TNFA, and human leukocyte antigen (HLA-DR/DQ) polymorphisms in mixed connective tissue disease (MCTD), we analyzed 24 patients and 229 healthy controls from Sweden. MICA and TNFa typing was performed by polymerase chain reaction (PCR) and genotyping. HLA-DR and -DQ were genotyped using PCR-sequence specific primers (PCR-SSP) and PCR-sequence-specific oligonucleotide probe (PCR-SSOP), respectively. For analysis of -308TNFA polymorphisms we performed PCR with restriction endonuclease enzymes. We found that the MICA5.1-5.1 genotype was positively associated with MCTD. Shared epitope genes (DRB1*01 and DRB1*04) were also significantly positively associated with MCTD. Polymorphism of -308TNFA was not differently distributed in MCTD patients compared with controls. Furthermore, we demonstrated that frequencies of three estimated haplotypes were increased in MCTD patients compared with controls. Interestingly, the haplotype with MICA allele 4 together with DRB1*04 and TNF1 alleles gives the most specific pattern for MCTD patients compared with controls. Our study demonstrates a clear contribution of HLA loci in susceptibility to MCTD in the Swedish population. Susceptibility to MCTD may be linked to the MICA4/HLA-DRB1*04/TNF1 haplotype and MICA 5.1-5.1 genotype. Mixed connective tissue disease was also associated with shared epitope genes, which in RA has been associated with a more severe disease. Whether these genotypes affect the clinical phenotype of MCTD needs to be determined.

Sporadic inclusion body myositis: pilot study on the effects of a home exercise program on muscle function, histopathology and inflammatory reaction

OBJECTIVE

To evaluate the safety and effect of a home training program on muscle function in 7 patients with sporadic inclusion body myositis.

DESIGN

The patients performed exercise 5 days a week over a 12-week period.

METHODS

Safety was assessed by clinical examination, repeated muscle biopsies and serum levels of creatine kinase. Muscle strength was evaluated by clinical examination, dynamic dynamometer and by a functional index in myositis.

RESULTS

Strength was not significantly improved after the exercise, however none of the patients deteriorated concerning muscle function. The histopathology was unchanged and there were no signs of increased muscle inflammation or of expression of cytokines and adhesion molecules in the muscle biopsies. Creatine kinase levels were unchanged. A significant decrease was found in the areas that were positively stained for EN-4 (a marker for endothelial cells) in the muscle biopsies after training.

CONCLUSION

The home exercise program was considered as not harmful to the muscles regarding muscle inflammation and function. Exercise may prevent loss of muscle strength due to disease and/or inactivity.

Idiopathic inflammatory myopathies - myositis

The inflammatory myopathies - myositis - encompass a heterogeneous group of chronic muscle disorders of unknown origin and with varying prognoses. New clinical phenotypes of myositis have been identified since the most widely used classification criteria were proposed in 1975. Based on clinical and histopathological features, inclusion body myositis was identified. Furthermore, the myositis-specific autoantibodies may also identify different clinical phenotypes and serve as prognostic markers. The different classifications and inclusion criteria that have been used in different studies make some epidemiological data uncertain. In order to improve our knowledge of causative factors, as well as of pathogenic mechanisms, there is a need for revision and also for an international acceptance of the classification criteria. During recent years, our knowledge has increased regarding the role of some genetic and environmental factors that could affect susceptibility for developing myositis as well as the prognosis. Whether there is an association between myositis and malignancies has been a subject of controversy for many years and recent epidemiological data have brought some clarification on this issue.

Development of the myositis activities profile--validity and reliability of a self-administered questionnaire to assess activity limitations in patients with polymyositis/dermatomyositis

OBJECTIVE

To develop a disease-specific questionnaire for assessing limitations in activities of daily life, the Myositis Activities Profile (MAP), and to investigate its validity and reliability.

METHODS

Groups of 10, 27, 31, and 17 patients with polymyositis (PM) or dermatomyositis (DM) participated in different parts of the study. In the first draft of the MAP, patients rated their difficulty and experienced importance of selected activities from the International Classification of Impairments, Disabilities, and Handicaps (ICIDH)-2 Beta-2 draft. The 37 highest rated activities formed a second draft of the MAP, which was analyzed for internal redundancy and consistency. For construct validity a third draft was correlated with CPK levels, the Functional Index in myositis (FI), the Arthritis Impact Measurement Scales-2 (AIMS2), the Health Assessment Questionnaire (HAQ), and subjective global disease impact. Test-retest reliability over one week was investigated.

RESULTS

There were several expected correlations (rs > 0.50) between subscales of the MAP and corresponding subscales of the AIMS2, and a 31 item MAP correlated moderately with the HAQ (rs = 0.70) and less with the FI (rs = 0.55), subjective global disease impact (rs = 0.43), and CPK levels (rs = 0.17). No systematic differences were found between test and retest, and weighted kappa coefficients ranged from Kw = 0.56 to 0.77.

CONCLUSION

The MAP seems to be a valid and reliable method for assessing activity limitations in patients with PM and DM.

Possible pathogenic mechanisms in inflammatory myopathies

The limitations associated with the different approaches into the pathogenesis of the IIM have resulted in incomplete knowledge of disease mechanisms in myositis. In most research, in which muscle tissue was used to study the different aspects of disease, biopsies with inflammatory infiltrates have been selected. Although inflammatory cell infiltrates are a characteristic feature of myositis, selecting patients with inflammatory cell infiltrates for investigations naturally introduces a selection bias. Only a few studies have been published on patients without inflammatory infiltrates but with muscle weakness, and few studies have included follow-up biopsies after different therapies. The heterogeneity of the population of patients with myositis is another limitation of the studies of pathogenic mechanisms. Although most studies classify patients according to the Bohan and Peter criteria [118, 119], some studies used histopathologic criteria [6], and only a few studies included characterization with myositis-specific autoantibodies. Because myositis-specific autoantibodies are often associated with certain clinical profiles, classification according to autoantibody profiles could be important to define differences in the pathogenesis of different phenotypes [3]. From available data on pathogenic mechanisms it is evident that cellular and humoral immune responses are involved in disease mechanisms of myositis, but whether there is a muscle-specific immune response cannot be answered by current studies. It is likely that other mechanisms are important for development of muscle weakness, including metabolic disturbances, and muscle weakness could be caused by different mechanisms in different IIM subsets or in patients in different phases of the disease. There could be early changes, which reversibly affect the metabolism, and later, irreversible changes, that could be dependent on muscle fiber damage and replacement of muscle tissue by connective tissue and fat. Current findings suggest that cytokines, which are produced in muscle tissue from different cell sources including inflammatory cells, endothelial cells, and muscle fibers, could affect muscle function. Careful follow-up studies, including the effect of therapies targeting different molecules on molecular expression in muscle tissue, are likely to increase our knowledge on disease mechanisms. A better understanding of which molecules and mechanisms affect muscle function is likely to lead to improved, less toxic therapies in patients with myositis. Many possible target molecules for blocking therapies, especially the proinflammatory cytokines IL-1 and TNF-alpha, have been identified and should be studied in appropriate clinical settings given the currently poor outcomes of many patients with IIM.

New possibilities to achieve increased understanding of disease mechanisms in idiopathic inflammatory myopathies

The development of new technologies within molecular biology and the mapping of the genome bring us closer to understanding the molecular basis of chronic inflammatory diseases, including the idiopathic inflammatory myopathies. This accomplishment appears particularly promising for the myopathies, because the muscle is an organ that is easily available for tissue studies and is thus particularly suitable for studies of molecular expression on both the gene and protein levels. The information gained from such studies will depend on the clinical characterization of the studied patients, which is another challenge concerning the inflammatory myopathies. In conjunction with the development of new technologies this area of clinical research is making progress through an international effort. As a result, new tools to assess disease activity and damage for inflammatory myopathies have been recently suggested. A combined effort to perform longitudinal studies on repeated muscle biopsies from patients who are well defined clinically, as well as genetically, is likely to bring us increased knowledge on disease mechanisms that could lead to the development of new therapies and an improved outcome for patients with chronic inflammatory myopathies.

Increased cancer incidence in a Swedish cohort of patients with systemic lupus erythematosus

OBJECTIVE

To assess the risk of cancer in patients with systemic lupus erythematosus (SLE).

METHODS

A population-based cohort of 5 715 hospitalised SLE patients was followed 1964-1995 through linkage of the Hospital Discharge Register to the National Swedish Cancer Register.

RESULTS

In all, 443 malignancies occurred during the observation-period. The overall risk was increased by 25% (SIR= 1.25, CI 95% 1.14-1.37) and lymphomas constituted the major excess risk. The risk of non-Hodgkin's lymphoma (NHL) was nearly 3-fold increased (SIR = 2.86, CI 95% 1.96-4.04). There was also an increased risk of lung cancer (SIR= 1.73, CI 95% 1.25-2.32) and squamous cell skin cancer (SIR= 1.53, CI 95% 0.98-2.28), which was most pronounced at more than 15 years of follow-up.

CONCLUSION

The major finding was a bimodal incidence pattern with an increased risk of lymphoma, mainly NHL, early during follow-up, but lung cancer and squamous skin cancer later on.

Interleukin-1alpha expression in capillaries and major histocompatibility complex class I expression in type II muscle fibers from polymyositis and dermatomyositis patients: important pathogenic features independent of inflammatory cell clusters in muscle tissue

OBJECTIVE

To address the hypothesis that endothelial cells and/or muscle fibers are primary targets in the disease process by analysis of muscle tissue from patients with polymyositis (PM) and dermatomyositis (DM).

METHODS

We included patients with laboratory signs and clinical symptoms typical of myositis, but without detectable infiltration of clusters of inflammatory cells in their muscle biopsy samples. An immunohistochemical technique was applied to identify CD3, CD68, lymphocyte function-associated antigen 1alpha, CD11b, very late activation antigen 4, endothelium 4, interleukin-1alpha (IL-1alpha), intercellular adhesion molecule 1, vascular cell adhesion molecule 1, IgG, IgM, IgA, and HLA-A/B/C in muscle tissue. Fiber type was defined by ATPase staining.

RESULTS

IL-1alpha expression was detected in endothelial cells of capillaries to a greater extent in patients than in controls, and class I major histocompatibility complex (MHC) expression was significantly increased in muscle fibers. We also observed that class I MHC expression was mainly confined to type II muscle fibers.

CONCLUSION

Our findings imply that defined molecular changes of blood vessels and muscle fibers are both independent of adjacent inflammatory infiltrates and could thus be primary events in the development of myositis. Moreover, both IL-1alpha and class I MHC molecules might be important for the development of clinical symptoms in PM and DM patients.

Longitudinal study of interleukin-10, tumor necrosis factor-alpha, anti-U1-snRNP antibody levels and disease activity in patients with mixed connective tissue disease

OBJECTIVE

To investigate the levels and relationship between IL-10, TNF-alpha, anti-U1snRNP antibodies and disease activity in longitudinally collected serum samples from patients with mixed connective tissue disease (MCTD).

METHODS

Six patients followed for 17-138 months were investigated with ELISA for estimation of cytokine levels and antibodies to the different epitopes of the U1snRNP. Disease activity was assessed by systemic lupus activity measure (SLAM).

RESULTS

IL-10 and TNF-alpha levels fluctuated with time in at least half of the patients. Three patients had increased IL-10 levels and two had increased TNF-alpha in all samples. There was no correlation between cytokine levels and disease activity or clinical manifestations. All patients had increased levels of antibodies to the main components of the U1snRNP. Both antibody levels and disease activity decreased with time. A correlation between TNF-alpha and U1snRNP antibody levels were observed in five patients.

CONCLUSIONS

Increased and fluctuating levels of IL-10 or TNF-alpha without correlation to disease activity were observed in MCTD patients. In some patients increased cytokine levels were observed over several years irrespective of disease activity indicating that they could be constitutively increased in these individuals.

Serial analysis of Ro/SSA and La/SSB antibody levels and correlation with clinical disease activity in patients with systemic lupus erythematosus

OBJECTIVE

To investigate the temporal correlation between anti-Ro/SSA and anti-La/SSB antibody levels and compare them with variation in clinical disease activity in patients with systemic lupus erythematosus (SLE).

METHODS

Sequential serum samples collected over 18-44 months from 18 anti-Ro/SSA positive patients with systemic lupus erythematosus were analysed by ELISA with recombinant Ro60, Ro52 and La antigens. Disease activity was assessed by the BILAG index.

RESULTS

Limited antibody level variation over time was found in most patients, but a subset displayed more changes and a co-variation between the levels of separate specificities was found in 40% of patients. In two patients antibody levels fluctuated with the global score. Antibodies also correlated with separate organ/systems involvement in individual patients.

CONCLUSION

The Ro60, Ro52 and La antibody profile is fixed at an early stage of disease and in most patients hardly changes. Patients with fluctuating levels tend to have a co-ordinated expression of these autoantibodies.

Increased endothelial expression of HLA-DQ and interleukin 1alpha in extra-articular rheumatoid arthritis. Results from immunohistochemical studies of skeletal muscle

OBJECTIVE

To investigate markers of endothelial activation in muscle biopsies from rheumatoid arthritis (RA) patients with and without extra-articular manifestations (ExRA).

PATIENTS AND METHODS

Nine consecutive ExRA patients were compared with nine RA controls without ExRA, matched for age, sex and duration of RA. Muscle biopsies were obtained from the lateral vastus or anterior tibial muscle. Macrophage and lymphocyte CD markers, HLA molecules, cytokines and adhesion molecules were investigated using immunohistochemistry, and stainings were evaluated using computer image analysis and conventional microscopy. Serum concentrations of soluble adhesion molecules, tumour necrosis factor alpha (TNF-alpha) and rheumatoid factor (RF) were determined using immunoassays.

RESULTS

The number of HLA-DQ-positive capillaries (P=0.039) and the expression of interleukin 1alpha (IL-1alpha) in endothelial cells (mean pairwise difference 0.26%; 95% confidence interval 0-0.52) were increased in ExRA patients compared with non-ExRA controls. There were no signs of inflammatory cell infiltrates or fibre degeneration. Serum levels of TNF-alpha, the soluble form of intercellular adhesion molecule 1, the soluble form of vascular cell adhesion molecule 1 and IgM RF were increased in the ExRA group.

CONCLUSION

The increased expression of HLA-DQ and IL-1alpha may indicate systemic endothelial activation in extra-articular RA, which could be of importance for cardiovascular comorbidity and mortality in such patients.

Skeletal muscle fibers express major histocompatibility complex class II antigens independently of inflammatory infiltrates in inflammatory myopathies

The aim of our study was to address the question of whether muscle fibers express major histocompatibility complex (MHC) class II in inflammatory myopathies. For this purpose we performed a systematic study of MHC class II antigen expression on muscle fiber membranes in muscle tissue from polymyositis and dermatomyositis patients in various stages of disease activity. Thirty-two patients with classical clinical signs of myositis were divided into subgroups depending on duration of clinical signs of myositis and presence or absence of inflammatory infiltrates in muscle tissue. Immunohistochemistry as well as double-immunofluorescence stainings were used to identify the presence of MHC class II in muscle tissue. MHC class I was included for comparison. Quantification of positive staining was performed using an image analysis system in addition to evaluation by manual microscopic scoring and laser confocal microscopy. It was demonstrated that a significant proportion of skeletal muscle fibers in inflammatory myopathies express MHC class II as well as MHC class I and that MHC antigen expression is independent of the inflammatory cell infiltration. Furthermore, there were no differences in staining pattern between polymyositis and dermatomyositis patients. Our results indicate that MHC class II and MHC class I molecules may be involved in initiating and maintaining the pathological condition in myositis rather than only being a consequence of a preceding local inflammation.

Percutaneous conchotome muscle biopsy. A useful diagnostic and assessment tool

OBJECTIVE

To evaluate the diagnostic yield, performance simplicity, and safety of the percutaneous conchotome muscle biopsy technique for clinical and research purposes in an outpatient rheumatology clinic.

METHODS

Biopsies taken by rheumatologists in an outpatient clinic during 1996 and 1997 were evaluated for histopathological and clinical diagnoses.

RESULTS

A total of 149 biopsies were performed on 122 patients. Physicians learned the method easily. Samples were of adequate size and quality to allow for diagnostics. In total 106 biopsies were taken due to different diagnostic suspicions: 24 polymyositis (PM) or dermatomyositis (DM); 43 PM, DM, or vasculitis in addition to another rheumatic condition; 19 systemic vasculitis; and 20 myalgias. Criteria for definite or probable PM/DM were fulfilled in 21 patients, 18 with positive biopsies. Thirteen patients received vasculitis as clinical diagnosis, 3 with positive biopsies. No patient with myalgia had a biopsy with inflammatory changes. Fifteen of 43 rebiopsies performed to assess disease activity had signs of active inflammation. In 48% there were changes in immunosuppressive therapy after biopsy results. Four complications occurred; one was a serious subfascial hematoma.

CONCLUSION

The percutaneous conchotome muscle biopsy technique gives a good size sample that allows for diagnostic evaluation and has a high yield in patients with myositis. It is a simple procedure, easy to learn and to perform, with a low complication rate and minimum discomfort for the patient. The method can preferably be used as a diagnostic tool and to perform repeated biopsies to assess the effect of a given therapy for both clinical and research purposes.

The physiology of inflammatory myopathies: an overview

The idiopathic inflammatory myopathies (IIMs) encompass a group of muscle disorders of unknown origin and pathogenesis characterized by symmetrical, proximal muscle weakness and by inflammatory infiltrates in muscle tissue. The mechanisms behind the loss of muscle function are largely unknown. It is often anticipated that the muscle weakness is caused by the inflammatory cells. However, inflammatory infiltrates are not always present in the muscle tissue and the infiltrates sometimes have a patchy distribution, which makes it difficult to explain the generalized muscle weakness merely by infiltration of inflammatory cells. We investigated patients at different stages of myositis: early myositis without detectable inflammatory infiltrates, active myositis with pronounced inflammatory infiltrates and chronic myositis with persisting muscle weakness but without detectable inflammatory cells in muscle tissues. In these studies, a better correlation was observed between the clinical symptoms and involvement of the capillaries with expression of the cytokine interleukin (IL)-1alpha and by the presence of major histocompatibility complex (MHC) class I expression on muscle fibres. Whether these molecules could affect muscle function is not known. Using phosphorus P-31 magnetic resonance spectroscopy decreased values of adenosine triphosphate (ATP) and phosphocreatine (PCr) levels were observed at rest. These metabolic abnormalities were further accentuated by exercise and increased PCr levels correlated with improved clinical status. The underlying mechanisms responsible for these biochemical abnormalities have not been defined but could be related to a disturbed tissue oxygenation.

The role of cytokines, chemokines, and adhesion molecules in the pathogenesis of idiopathic inflammatory myopathies

Cytokines, chemokines, and adhesion molecules are important mediators in chronic inflammation and in immune regulation. In idiopathic inflammatory myopathies (IIM), increased expression of proinflammatory cytokines particularly interleukin (IL)-1alpha and IL-1beta, tumor necrosis factor (TNF)-alpha and macrophage inflammatory proteins (MIP)-1alpha, as well as of the inhibitory cytokines transforming growth factor (TGF)-beta was observed in muscle. There was no difference in cytokine and chemokine pattern between polymyositis, dermatomyositis, and inclusion body myositis, which could indicate that similar pathogenetic mechanisms are involved in these subsets of myositis. A prominent finding of IL-1alpha expression in endothelial cells, both in patients with active inflammation and in patients with chronic persisting muscle weakness without inflammation, makes this an interesting molecule in understanding the mechanisms for the pathogenesis of muscle weakness. Involvement of the blood vessels in the pathogenesis of myositis was further supported by increased expression of adhesion molecules and by a phenotypical expression of endothelial cells, resembling high endothelium venules in all three subsets of IIM. The molecular studies to date indicate a role of the microvessels in the pathogenesis of IIM not only in DM, as was previously suggested, but also in PM and IBM. The studies also indicate that IL-1alpha could be a target molecule for new therapeutical interventions.

New developments in the role of cytokines and chemokines in inflammatory myopathies

Cytokines and chemokines are important molecules in the inflammatory response and in immune regulation. Investigations of the production of these molecules in the target organ of inflammation is of particular interest to obtain increased knowledge of the pathogenesis of chronic inflammatory disorders. By investigations of muscle tissue from patients with polymyositis, inclusion-body myositis (IBM), and dermatomyositis a predominance of the cytokines interleukin-1 alpha and -1 beta and transforming growth factor beta was observed. Among the chemokines investigated, macrophage inflammatory protein 1 alpha was the most commonly found molecule. A similar pattern of cytokines and chemokines was present in polymyositis, IBM, and dermatomyositis. This was also true for the pronounced interleukin-1 alpha expression in the endothelial cells of capillaries and venules. The results of these studies suggest a major role of the proinflammatory cytokines interleukin-1 alpha and -1 beta and the importance of the endothelial cells in the pathogenesis not only in dermatomyositis, as previously suggested, but also in polymyositis and IBM. Furthermore, the pronounced interleukin-1 expression in the inflammatory myopathies makes this molecule an interesting potential target for development of future therapies for these disorders.