Mycobacterial heat shock protein 65 (mbHSP65)-induced atherosclerosis: Preventive oral tolerization and definition of atheroprotective and atherogenic mbHSP65 peptides

OBJECTIVE

The aim of this study was to identify atherogenic and atheroprotective peptides of bacterial HSP60 [taking mycobacterial HSP65 (mbHSP65) as a potent paradigmatic representative] that could be used as candidates for an orally applied tolerizing vaccine against atherosclerosis.

METHODS

ApoE(-/-) mice were immunized with mbHSP65 protein or peptides, given mbHSP65 orally and then kept either on chow or high cholesterol diet. Atherosclerosis was assessed by en face and immunohistological analysis. Anti-HSP autoantibodies were detected by ELISA. The number and in vitro suppressive function of splenic and lymph node regulatory T cells (Tregs) were analyzed by flow cytometry. Specific T cell reactivity against mbHSP65 protein or peptides was assessed by proliferation assay.

RESULTS

Decreased lesion size was accompanied by (a) increased splenic Treg numbers; (b) increased interleukin (IL)-10 mRNA levels in the aorta; (c) increased levels of anti-mbHSP65 and anti-mouse HSP60 antibodies pointing to pro-eukaryotic HSP60 humoral crossreaction, not curtailed by oral tolerization; (d) most importantly, we identified and functionally characterized novel atherogenic and atheroprotective mbHSP65 epitopes.

CONCLUSION

Atheroprotective mbHSP65 peptides may be considered as potential candidates for the development of a tolerizing vaccine to prevent and treat atherosclerosis, while keeping protective immunity to non-atherogenic domains of mbHSP65 intact.

Effects of adalimumab treatment on endothelial cell activation markers in the skeletal muscle of patients with rheumatoid arthritis

OBJECTIVES

Patients with rheumatoid arthritis (RA), particularly those with severe disease, have increased risk of cardiovascular disease (CVD). Previous studies suggest that endothelial cell activation may contribute to this co-morbidity, and that treatment with tumour necrosis factor (TNF) inhibitors could reduce the risk of CVD in these patients. The aim of this study was to investigate endothelial cell activation markers in muscle tissue of patients after adalimumab treatment.

METHODS

Patients with active RA who started treatment with adalimumab 40 mg every two weeks were included. Muscle biopsies taken before and 3 months after start of treatment were available from 11 patients (9 females, mean age 54.2 years, median disease duration 6.5 years, 91% anti-CCP positive, 7 on methotrexate [median dose 20 mg/week]). None of the patients had clinical signs of myopathy. IL-1α and HLA-DQ were investigated by immunohistochemistry. Quantification was performed by computer assisted image analysis.

RESULTS

Disease activity, measured by DAS28 decreased (mean 5.5 vs. 4.1; p=0018). A good or moderate EULAR response was seen in 6/11 patients. HLA-DQ was mainly expressed in endothelial cells in capillaries, whereas IL-1α was mainly seen in larger vessels. HLA-DQ expression decreased significantly after treatment (p=0.041). There was a similar trend for IL-1α, in particlar in EULAR good/moderate responders.

CONCLUSIONS

Adalimumab treatment was associated with decreased expression of endothelial markers previously associated with severe systemic inflammation in RA. Our findings indicate a reduced endothelial activation in patients treated with anti-TNF drugs, which might contribute to a lower risk of cardiovascular co-morbidity.

The pattern of acute injuries in patients from alpine skiing accidents has changed during 2000-2011: analysis of clinical and radiological data at a level I trauma center

OBJECTIVES

During the last decade, many educational efforts and technological improvements have been made to protect skiing athletes from injuries. Whether these efforts have changed the pattern of acute injuries from skiing casualties has not yet been shown on a medical basis, which this longitudinal study examines.

METHODS

All patients transferred to the Department of Radiology of our level I trauma center for acute emergency computed tomography (CT) after alpine skiing accidents from 2000 to 2011 were included. We hypothesized that only patients with clinical suspicion for injuries were admitted for acute CT.

RESULTS

Of all acute patients after skiing accidents, 2,252 could be included. From 2000 to 2011, all cerebral injuries and vascular arterial injuries statistically significantly decreased (p < 0.05, respectively). However, extremity fractures, facial fractures, and vertebral fractures increased (p < 0.04, respectively). The number of cerebral hemorrhages, thoracic injuries, and abdominal injuries remained unchanged (p = NS). The mean (SD) number of all initial radiological examinations per victim statistically significantly decreased from 2.3 (0.7) in 2000 to 1.5 (0.6) in 2011, whereas the admissions for acute CT have significantly increased (p < 0.02; respectively).

CONCLUSIONS

Acute radiological evaluation in skiing accidents has changed during the last decade. The decrease in overall cerebral injuries might be a function of the increasing use of skiing helmets. A protection of the extremities, trunk, spine, and face, however, needs further improvements and their radiological assessment with CT warrants attention in skiing casualties.

The immunology of fibrosis

Fibrosis is the production of excessive amounts of connective tissue, i.e., scar formation, in the course of reactive and reparative processes. Fibrosis develops as a consequence of various underlying diseases and presents a major diagnostically and therapeutically unsolved problem. In this review, we postulate that fibrosis is always a sequela of inflammatory processes and that the many different causes of fibrosis all channel into the same final stereotypical pathways. During the inflammatory phase, both innate and adaptive immune mechanisms are operative. This concept is exemplified by fibrotic diseases that develop as a consequence of tissue damage, primary inflammatory diseases, fibrotic alterations induced by foreign body implants, "spontaneous" fibrosis, and tumor-associated fibrotic changes.

Autoreactive HSP60 epitope-specific T-cells in early human atherosclerotic lesions

Atherosclerosis is a multifactorial chronic inflammatory disease characterized by the presence of T-cells, macrophages, and dendritic cells in the arterial intima. Classical risk factors lead to over-expression of stress proteins, especially heat shock protein 60 (HSP60). HSP60 on the surface of arterial endothelial cells (ECs) then becomes a target for pre-existing adaptive anti-HSP60 immunity resulting in infiltration of the intima by mononuclear cells. In the present study, T-cells derived from early, clinically still inapparent human atherosclerotic lesions were analyzed phenotypically and for their reactivity against HSP60 and HSP60-derived peptides. HSP60 was detected in ECs and CD40- and HLA Class II-positive cells within the intima. Effector memory CD4⁺ T-cells producing high amounts of interferon-γ and low levels of interleukin-4 were the dominant subpopulation. T-cells derived from late lesions displayed a more restricted T-cell receptor repertoire to HSP60-derived peptides than those isolated from early lesions. Increased levels of soluble HSP60 and circulating anti-human HSP60 autoantibodies were found in donors with late but not early lesions. This is the first functional study of T-cells derived from early human atherosclerotic lesions that supports the previously proposed concept that HSP60-reactive T-cells initiate atherosclerosis by recognition of atherogenic HSP60 epitopes.

The autoimmune concept of atherosclerosis

PURPOSE OF REVIEW

This review summarizes the recent data on the 'Autoimmune Concept of Atherosclerosis', according to which the first stage of this disease is due to an autoimmune reaction against arterial endothelial cells expressing heat shock protein 60 (HSP60) and adhesion molecules when stressed by classical atherosclerosis risk factors. Special emphasis is put on oxidized low-density lipoproteins as early endothelial stressors.

RECENT FINDINGS

Plasma cholesterol and LDL levels considered 'normal' by the medical community are possibly too high from an evolutionary viewpoint. The proinflammatory milieu at sites of early atherosclerotic lesions could be conducive to oxidation of LDL in situ. LDL oxidation can also take place at nonvascular sites or in the circulation under general proinflammatory conditions explaining its proatherosclerotic role in 'normocholesterolemic' individuals.

SUMMARY

We hypothesize that the plasma cholesterol and LDL levels currently considered normal are evolutionarily too high. Cholesterol and/or oxidized low-density lipoprotein, even as a mild HSP60-inducing endothelial stressor, function as a ubiquitous risk factor. If this hypothesis is true, most members of developed societies might be at risk to develop atherosclerotic plaques at anti-HSP60-immunity-triggered intimal inflammatory foci, irrespective of the primary risk-factor(s).

Heat shock protein 60 and immune inflammatory responses in atherosclerosis

Hallmarks of inflammation in various cardiovascular diseases, notably atherosclerosis, have been observed for a long time. However, evidence for an (auto)antigen-driven process at these sites of inflammation has come forward only recently. Heat shock proteins (HSPs) have been identified as playing either immunologically mediated disease promoting or protective roles. HSP60 has been shown to trigger innate and adaptive immune responses that initiate the earliest still reversible inflammatory stage of atherosclerosis. HSP60 is structurally highly conserved and abundantly expressed by prokaryotic and eukaryotic cells under stressful conditions. Beneficial protective immunity to microbial HSP60 acquired by infection or vaccination and bona fide autoimmunity to biochemically altered autologous HSP60 is present in all humans. In vitro and in vivo experiments have demonstrated that classical atherosclerosis risk factors can act as endothelial stressors that provoke the simultaneous expression of adhesion molecules and of HSP60 in mitochondria, in cytoplasm, and on the cell surface, where it acts as a "danger signal" for cellular and humoral immune reactions. Hence, protective, preexisting anti-HSP60 immunity may have to be "paid for" by harmful (auto)immune cross-reactive attack on arterial endothelial cells maltreated by atherosclerosis risk factors. These experimentally and clinically proven findings are the basis for the autoimmune concept of atherosclerosis.

A longitudinal, integrated, clinical, histological and mRNA profiling study of resistance exercise in myositis

Polymyositis and dermatomyositis are orphan, chronic skeletal muscle disorders characterized by weakness, infiltrations by mononuclear inflammatory cells, and fibrosis. Until recently, patients were advised to refrain from physical activity because of fears of exacerbation of muscle inflammation. However, recent studies have shown that moderate exercise training in combination with immunosuppressive drugs can improve muscle performance. Despite the positive effects of exercise training, the molecular mechanisms underlying the exercise-associated clinical improvements remain poorly understood. The present study was designed to define, at the molecular level, the effects of resistance exercise training on muscle performance and disease progression in myositis patients. We evaluated changes in muscle strength, histology and genome-wide mRNA profiles to determine the beneficial effects of exercise and determine the possible molecular changes associated with improved muscle performance. A total of 8 myositis patients underwent a 7-wk resistance exercise training program that resulted in improved muscle strength and increased maximal oxygen uptake (VO(2max)). Training also resulted in marked reductions in gene expression, reflecting reductions in proinflammatory and profibrotic gene networks, changes that were also accompanied by a reduction in tissue fibrosis. Consistent with the exercise-associated increase in VO(2max), a subset of transcripts was associated with a shift toward oxidative metabolism. The changes in gene expression reported in the present study are in agreement with the performance improvements induced by exercise and suggest that resistance exercise training can induce a reduction in inflammation and fibrosis in skeletal muscle.

Impaired myofibrillar function in the soleus muscle of mice with collagen-induced arthritis

OBJECTIVE

Progressive muscle weakness is a common feature in patients with rheumatoid arthritis (RA). However, little is known about whether the intrinsic contractile properties of muscle fibers are affected in RA. This study was undertaken to investigate muscle contractility and the myoplasmic free Ca2+ concentration ([Ca2+](i)) in the soleus, a major postural muscle, in mice with collagen-induced arthritis (CIA).

METHODS

Muscle contractility and [Ca2+](i) were assessed in whole muscle and intact single-fiber preparations, respectively. The underlying mechanisms of contractile dysfunction were assessed by investigating redox modifications using Western blotting and antibodies against nitric oxide synthase (NOS), superoxide dismutase (SOD), 3-nitrotyrosine (3-NT), carbonyl, malondialdehyde (MDA), and S-nitrosocysteine (SNO-Cys).

RESULTS

The tetanic force per cross-sectional area was markedly decreased in the soleus muscle of mice with CIA, and the change was not due to a decrease in the amplitude of [Ca2+](i) transients. The reduction in force production was accompanied by slowing of the twitch contraction and relaxation and a decrease in the maximum shortening velocity. Immunoblot analyses showed a marked increase in neuronal NOS expression but not in inducible or endothelial NOS expression, which, together with the observed decrease in SOD2 expression, favors peroxynitrite formation. These changes were accompanied by increased 3-NT, carbonyl, and MDA adducts content in myofibrillar proteins from the muscles of mice with CIA. Moreover, there was a significant increase in SNO-Cys content in myosin heavy-chain and troponin I myofibrillar proteins from the soleus muscle of mice with CIA.

CONCLUSION

These findings show impaired contractile function in the soleus muscle of mice with CIA and suggest that this abnormality is due to peroxynitrite-induced modifications in myofibrillar proteins.

Effects of HMGB1 on in vitro responses of isolated muscle fibers and functional aspects in skeletal muscles of idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIMs) are heterogeneous rheumatic disorders of unknown cause characterized by muscle weakness, inflammatory cell infiltrates, and major histocompatibility complex (MHC) class I expression on muscle fibers. The nonhistone nuclear protein alarmin high-mobility group box 1 protein (HMGB1) has been detected extranuclearly in muscle biopsies from patients with IIMs. We hypothesize that HMGB1 has a central role in the cause of muscle weakness, particularly in the early phases of IIMs. Experiments were performed on skeletal muscle fibers isolated from adult mice, which were exposed to recombinant interferon (IFN)-gamma or HMGB1. The myoplasmic free [Ca(2+)] was measured. Stimulation with IFN-gamma resulted in increased HMGB1 expression in muscle nuclei and the myoplasm. Exposure to HMGB1 induced a reversible up-regulation of MHC class I in the muscle fibers. However, HMGB1 exposure caused an irreversible decrease in Ca(2+) release from the sarcoplasmic reticulum during fatigue, induced by repeated tetanic contractions. HMGB1 and MHC class I were frequently colocalized in the myoplasm of muscle fibers in muscle biopsies from patients with early IIMs. However, HMGB1-expressing fibers outnumbered fibers expressing MHC class I. Our data indicate that HMGB1 could be an early inducer of skeletal muscle dysfunction in IIMs.

Upregulation of MHC class I in transgenic mice results in reduced force-generating capacity in slow-twitch muscle

Expression of major histocompatibility complex (MHC) class I in skeletal muscle fibers is an early and consistent finding in inflammatory myopathies. To test if MHC class I has a primary role in muscle impairment, we used transgenic mice with inducible overexpression of MHC class I in their skeletal muscle cells. Contractile function was studied in isolated extensor digitorum longus (EDL, fast-twitch) and soleus (slow-twitch) muscles. We found that EDL was smaller, whereas soleus muscle was slightly larger. Both muscles generated less absolute force in myopathic compared with control mice; however, when force was expressed per cross-sectional area, only soleus muscle generated less force. Inflammation was markedly increased, but no changes were found in the activities of key mitochondrial and glycogenolytic enzymes in myopathic mice. The induction of MHC class I results in muscle atrophy and an intrinsic decrease in force-generation capacity. These observations may have important implications for our understanding of the pathophysiological processes of muscle weakness seen in inflammatory myopathies. Muscle Nerve, 2008.

Monocytes are essential for inhibition of synovial T-cell glucocorticoid-mediated apoptosis in rheumatoid arthritis

Introduction

Rheumatoid arthritis (RA) is characterized by synovial inflammation with local accumulation of mononuclear cells such as macrophages and lymphocytes. We previously demonstrated that intra-articular glucocorticoids decrease the synovial tissue (ST) T-cell population and therefore aimed to investigate whether this is mediated through modulation of apoptosis.

Methods

Apoptosis and cell phenotype were evaluated by immunohistochemistry and dual-immunofluorescence in synovial biopsy sections from 12 RA patients before and after a mean of 11 days of an intra-articular triamcinolone knee injection. In vitro, RA synovial fluid (SF)-derived T cells were evaluated for Annexin V expression by multicolor flow cytometry after 24-hour exposure to dexamethasone, methylprednisolone, or triamcinolone. We also tested induction of apoptosis by dexamethasone on psoriatic arthritis SF-derived T cells using the same method.

Results

Intra-articular glucocorticoids reduced ST T cells but not macrophage number. ST apoptosis levels were unchanged following treatment, virtually absent from lymphoid aggregates, and minimal in CD3⁺ cells both before and after treatment. RA SF T cells were resistant to glucocorticoid-induced apoptosis when cultured in the presence of monocytes but were rendered sensitive to all three tested compounds upon SF isolation. Furthermore, transwell coculture of monocytes and T cells demonstrated that soluble factor(s) and not cellular contact are essential for T-cell resistance to glucocorticoid-mediated apoptosis. This feature is RA-specific as far as dexamethasone-induced apoptosis in nonisolated SF T cells obtained from psoriatic arthritis patients is concerned.

Conclusions

We demonstrate that monocytes rescue synovial T cells from glucocorticoid-induced apoptosis, a feature that is specific for RA. To overcome this, we propose the use of monocyte-targeted therapies rather than T-cell apoptosis-inducing therapies.

Developments in the scientific and clinical understanding of inflammatory myopathies

The idiopathic inflammatory myopathies are chronic autoimmune disorders sharing the clinical symptom of muscle weakness and, in typical cases, inflammatory cell infiltrates in muscle tissue. During the last decade, novel information has accumulated supporting a role of both the innate and adaptive immune systems in myositis and suggesting that different molecular pathways predominate in different subsets of myositis. The type I interferon activity is one such novel pathway identified in some subsets of myositis. Furthermore, nonimmunological pathways have been identified, suggesting that factors other than direct T cell-mediated muscle fibre necrosis could have a role in the development of muscle weakness.

Systemic TNF blockade does not modulate synovial expression of the pro-inflammatory mediator HMGB1 in rheumatoid arthritis patients--a prospective clinical study

Introduction

High-mobility group box chromosomal protein 1 (HMGB1) has recently been identified as an endogenous mediator of arthritis. TNF and IL-1β, pivotal cytokines in arthritis pathogenesis, both have the ability to induce the release of HMGB1 from myeloid and dendritic cells. It was, therefore, decided to investigate whether treatment based on TNF blockade in rheumatoid arthritis (RA) affects the expression of synovial HMGB1.

Methods

Repeated arthroscopy-guided sampling of synovial tissue was performed in nine patients with RA before and nine weeks after initiation of anti-TNF mAb (infliximab) therapy. Synovial biopsy specimens were analysed for HMGB1 protein by immunohistochemical staining and for HMGB1 mRNA expression by real-time reverse transcriptase PCR (RT-PCR). Statistical evaluations were based on Wilcoxon's signed rank tests or Spearman rank sum tests.

Results

Aberrant, extranuclear HMGB1 and constitutive nuclear HMGB1 expression, with histological signs of inflammation, were evident in all biopsies obtained before infliximab therapy. Signs of inflammation were still evident in the second biopsies obtained nine weeks after initiation of infliximab therapy. The cytoplasmic and extracellular expression of HMGB1 decreased in five patients, remained unchanged in one patient and increased in three patients, making the overall change in HMGB1 protein expression not significant. No correlation between the clinical response, as measured by disease activity score calculated for 28 joints (DAS28) or the American College of Rheumatology response criteria (ACR 20, 50, and 70), and the direction of change of HMGB1 expression in individual patients could be discerned. In addition, infliximab therapy did not alter HMGB1 mRNA synthesis.

Conclusion

Pro-inflammatory HMGB1 expression during rheumatoid synovitis was not consistently influenced by TNF-blocking therapy with infliximab. This suggests that TNF is not the main inducer of extranuclear HMGB1 during synovitis and that HMGB1 may represent a TNF-independent molecule that could be considered as a possible target for future therapeutic intervention in RA.

A high incidence of disease flares in an open pilot study of infliximab in patients with refractory inflammatory myopathies

OBJECTIVE

To investigate the effect of the tumour necrosis factor (TNF) blocking agent infliximab in patients with treatment-resistant inflammatory myopathies.

METHODS

A total of 13 patients with refractory polymyositis (PM), dermatomyositis (DM), or inclusion body myositis (IBM) were treated with 4 infliximab infusions (5 mg/kg body weight) over 14 weeks. Outcome measures included myositis disease activity score with improvement defined according to The International Myositis Assessment and Clinical Studies Group (IMACS), and MRI. Repeated muscles biopsies were investigated for cellular infiltrates, major histocompatibility complex (MHC) class I and II, TNF, interleukin (IL)1alpha, IL6, high mobility group box chromosomal protein 1 (HMGB-1), interferon gamma (IFNgamma), myxovirus resistance protein A (MxA) and membrane attack complex (MAC) expression. Type I IFN activity was analysed in sera.

RESULTS

Nine patients completed the study. Three patients discontinued due to adverse events and one due to a discovered malignancy. Three of the completers improved by >or=20% in three or more variables of the disease activity core set, four were unchanged and two worsened >or=30%. No patient improved in muscle strength by manual muscle test. At baseline, two completers had signs of muscle inflammation by MRI, and five at follow-up. T lymphocytes, macrophages, cytokine expression and MAC deposition in muscle biopsies were still evident after treatment. Type I IFN activity was increased after treatment.

CONCLUSIONS

Infliximab treatment was not effective in refractory inflammatory myopathies. In view of radiological and clinical worsening, and activation of the type I IFN system in several cases, infliximab is not an alternative treatment in patients with treatment-resistant myositis.

Effects of immunosuppressive treatment on microsomal prostaglandin E synthase 1 and cyclooxygenases expression in muscle tissue of patients with polymyositis or dermatomyositis

OBJECTIVES

To investigate the expression of microsomal prostaglandin E (PGE) synthase 1 (mPGES-1) and cyclooxygenase (COX) in muscle biopsies from patients with polymyositis or dermatomyositis before and after conventional immunosuppressive treatment.

METHODS

mPGES-1 and COX expression was evaluated by immunohistochemistry in muscle tissue from healthy individuals and from patients with polymyositis or dermatomyositis before and after conventional immunosuppressive treatment. The number of inflammatory cell infiltrates, T lymphocytes and macrophages was estimated before and after treatment. To localise the mPGES-1 expression double immunofluorescence was performed with antibodies against mPGES-1, CD3, CD68, CD163 and a fibroblast marker. A functional index was used to assess muscle function.

RESULTS

In patients with myositis, mPGES-1, COX-2 and COX-1 expression was significantly higher compared to healthy individuals and associated with inflammatory cells. Double immunofluorescence demonstrated a predominant expression of mPGES-1 in macrophages. Conventional immunosuppressive treatment resulted in improved but still lower muscle function than normal. A decreased number of CD68-positive macrophages and reduced COX-2 expression in muscle tissue was also seen. By contrast, following the same treatment no significant changes were observed in muscle tissue regarding number of infiltrates, T lymphocytes, CD163-positive macrophages or mPGES-1 protein levels.

CONCLUSIONS

Increased expression of mPGES-1, COX-1 and COX-2 at protein level was observed in muscle tissue from patients with myositis compared to healthy individuals. Conventional immunosuppressive treatment led to a significant downregulation of COX-2 in myositis muscle tissue. However, the expression of mPGES-1 and COX-1 remained unchanged indicating a role of these enzymes in the chronicity of these diseases.

Immune mechanisms in the pathogenesis of idiopathic inflammatory myopathies

Idiopathic inflammatory myopathies (IIMs), comprising polymyositis, dermatomyositis, and inclusion-body myositis, are characterized by inflammatory cell infiltrates in skeletal muscle tissue, muscle weakness, and muscle fatigue. The cellular infiltrates often consist of T lymphocytes and macrophages but also, in some cases, B lymphocytes. Emerging data have led to improved phenotypic characterization of the inflammatory cells, including their effector molecules, in skeletal muscle, peripheral blood, and other organs that are frequently involved, such as skin and lungs. In this review we summarize the latest findings concerning the role of T lymphocytes, B lymphocytes, dendritic cells, and other antigen-presenting cells in the pathophysiology of IIMs.

Immunolocalization of interleukin-1 receptors in the sarcolemma and nuclei of skeletal muscle in patients with idiopathic inflammatory myopathies

OBJECTIVE

Interleukin-1 (IL-1) acts via its receptors to induce gene expression that mediates protein synthesis involved in inflammation. Increased expression of IL-1alpha and IL-1beta in muscle tissue from patients with polymyositis and dermatomyositis has been demonstrated. It is not known whether the reciprocal IL-1 receptors are expressed in human muscle tissue. The purpose of this study was to investigate the expression of IL-1 receptors and their ligands in muscle tissue from patients with myositis and from healthy controls.

METHODS

Muscle biopsy tissues from 10 patients with polymyositis or dermatomyositis and 7 healthy control subjects were investigated by immunohistochemistry using antibodies against IL-1 receptor type I (IL-1RI), IL-1RII, IL-1alpha, IL-1beta, and IL-1 receptor antagonist (IL-1Ra). Quantification was performed by computerized image analysis, and localization of expression was determined by double staining using immunofluorescence and confocal microscopy.

RESULTS

In tissue samples from the patients, IL-1RI and IL-1RII were expressed in muscle fibers, inflammatory cells, and endothelial cells. Expression in muscle fibers was localized to the sarcolemma and nuclei. IL-1alpha was expressed in endothelial cells and inflammatory cells, whereas IL-1beta and IL-1Ra were expressed only in inflammatory cells. Expression of the two IL-1 receptors and their ligands was significantly higher in patients than in controls. IL-1 receptor expression on muscle fibers was most pronounced in the vicinity of cells expressing IL-1alpha and IL-1beta.

CONCLUSION

The increased expression of IL-1 receptor and the colocalization with reciprocal ligands in patients with myositis but not in healthy controls support the hypothesis of a crucial role of IL-1 in the pathogenesis of polymyositis and dermatomyositis.

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.

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.

Intraarticular glucocorticoid treatment reduces inflammation in synovial cell infiltrations more efficiently than in synovial blood vessels

OBJECTIVE

To investigate whether intraarticular (IA) glucocorticoid (GC) therapy diminishes synovial cell infiltration, vascularity, expression of proinflammatory cytokines, and adhesion molecule levels in patients with chronic arthritides.

METHODS

Thirty-one patients with chronic arthritides received a single IA injection of triamcinolone hexacetonide to treat active large-joint inflammation. Synovial biopsy specimens were obtained with arthroscopic guidance before and 9-15 days after injection. The presence of T lymphocytes, macrophages, intercellular adhesion molecule 1 (ICAM-1), vascular endothelial growth factor (VEGF), the pan-endothelial marker CD31, and the proinflammatory cytokines interleukin-1alpha (IL-1alpha), IL-1beta, tumor necrosis factor (TNF), and high mobility group box chromosomal protein 1 (HMGB-1) was studied by immunohistochemistry and real-time reverse transcriptase-polymerase chain reaction.

RESULTS

IA GC treatment resulted in good clinical response in 29 of 31 joints. After therapeutic intervention, the number of synovial T lymphocytes declined, whereas the number of macrophages remained unchanged. Overall synovial protein expression of TNF, IL-1beta, extranuclear HMGB-1, VEGF, and ICAM-1 was reduced at followup tissue sampling, while no significant effects were observed regarding vascularity. In contrast, expression of IL-1alpha, VEGF, and cytoplasmic HMGB-1 protein in vascular endothelial cells was not affected. GC therapy down-regulated levels of messenger RNA encoding IL-1alpha and IL-1beta, but not TNF or HMGB-1.

CONCLUSION

Synovial cell infiltration and proinflammatory cytokine expression were affected in a multifaceted manner by IA GC treatment. Marked reduction of synovial T lymphocytes, TNF, IL-1beta, extranuclear HMGB-1, ICAM-1, and VEGF occurred in association with beneficial clinical effects. Unexpectedly, macrophage infiltration and proinflammatory endothelial cytokine expression remained unchanged. These findings may reflect mechanisms controlling the transiency of clinical improvement frequently observed after IA GC injection.

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.