Expert Perspective: Management of Refractory Inflammatory Myopathy.

The idiopathic inflammatory myopathies (IIMs) are chronic disorders characterized by inflammation in skeletal muscle but also in other organs such as the skin, lungs, joints, gastrointestinal tract, and heart. The effect of immunosuppressive treatment varies between individual patients and between organ manifestations within the same individual. Many patients respond poorly to first-line treatment with glucocorticoids and other immunosuppressive agents such as methotrexate or azathioprine, with symptoms persisting in the muscles, skin, and lungs, leading to refractory disease. Management of refractory IIM is a clinical challenge, and a systematic approach is proposed to better understand the lack of treatment response, in order to guide disease management. The first step in the management of refractory IIM is to recognize whether remaining symptoms are caused by persistent inflammation in the affected tissue or whether the symptoms may be attributable to damage preceding inflammation. Thus, a second diagnostic examination is recommended. Second, in particular for patients with remaining muscle weakness, it is important to ascertain whether the diagnosis of myositis is correct or whether another underlying muscle disorder could explain the symptoms. Third, with confirmation of remaining inflammation in the tissues, a strategy to change treatment needs to be undertaken. Few controlled trials are available to guide our treatment strategies. Furthermore, different subgroups of patients may benefit from different therapies, and different organ manifestations may respond to different therapies. In this context, subgrouping of patients with IIM based on autoantibody profile may be helpful, as there are emerging data from open studies and case series to support the notion of a varying treatment response in different autoantibody-defined subgroups of IIM patients.

Case report of COVID-19 in an elderly patient: could SARS-CoV2 trigger myositis?

Though the exact etiology of autoimmune diseases still remains not completely known, there are various factors which are known to contribute to be trigger of autoimmune diseases. Viral infection is known to be among the other. It is known as the infection from severe acute respiratory syndrome coronavirus (SARS-CoV) and Middle East respiratory syndrome coronavirus (MERS-CoV) can be an autoimmune trigger, so, we suppose that SARS-Coronavirus (SARS-CoV-2) could be as well. Several authors have highlighted the temporal consequence between SARS-CoV-2 and autoimmune diseases. In this case report we described a patient admitted for COVID-19 pneumonia with completely negative autoimmunity at admission who developed major pulmonary interstitial disease. During the hospitalization the weaning difficulties from oxygen led us to the repetition of autoimmunity pattern which became positive (both during hospitalization then after two months from dismission) with marked positivity for specific antibodies for myositis even after the patient's infectious healing. In the follow-up, the patient continued to have asthenia and muscle weakness despite steroid therapy. She is still in follow-up and will be further evaluated over time. Can we therefore think that in this case the development of autoimmunity can persist beyond the infectious phase and determine over time the development of a real autoimmune myositis?

Autoimmune and rheumatic musculoskeletal diseases as a consequence of SARS-CoV-2 infection and its treatment.

The coronavirus disease-2019 (COVID-19) pandemic is likely to pose new challenges to the rheumatology community in the near and distant future. Some of the challenges, like the severity of COVID-19 among patients on immunosuppressive agents, are predictable and are being evaluated with great care and effort across the globe. A few others, such as atypical manifestations of COVID-19 mimicking rheumatic musculoskeletal diseases (RMDs) are being reported. Like in many other viral infections, severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection can potentially lead to an array of rheumatological and autoimmune manifestations by molecular mimicry (cross-reacting epitope between the virus and the host), bystander killing (virus-specific CD8 + T cells migrating to the target tissues and exerting cytotoxicity), epitope spreading, viral persistence (polyclonal activation due to the constant presence of viral antigens driving immune-mediated injury) and formation of neutrophil extracellular traps. In addition, the myriad of antiviral drugs presently being tried in the treatment of COVID-19 can result in several rheumatic musculoskeletal adverse effects. In this review, we have addressed the possible spectrum and mechanisms of various autoimmune and rheumatic musculoskeletal manifestations that can be precipitated by COVID-19 infection, its therapy, and the preventive strategies to contain the infection.

Macrophagic myofasciitis and subcutaneous pseudolymphoma caused by aluminium adjuvants.

Aluminium hydroxide is a well-known adjuvant used in vaccines. Although it can enhance an adaptive immune response to a co-administered antigen, it causes adverse effects, including macrophagic myofasciitis (MMF), subcutaneous pseudolymphoma, and drug hypersensitivity. The object of this study is to demonstrate pediatric cases of aluminium hydroxide-induced diseases focusing on its rarity, under-recognition, and distinctive pathology. Seven child patients with biopsy-proven MMF were retrieved from the Seoul National University Hospital (SNUH) pathology archives from 2015 to 2019. The medical records and immunisation history were reviewed, and a full pathological muscle examination was carried out. The mean age was 1.7 years (8.9-40 months), who had records of vaccination against hepatitis B, hepatitis A, and tetanus toxoid on the quadriceps muscle. The chief complaints were muscle weakness (n = 6), delayed motor milestones (n = 6), instability, dysarthria, and involuntary movement (n = 1), swallowing difficulty (n = 1), high myopia (n = 1), and palpable subcutaneous nodules with skin papules (n = 1). Muscle biopsy showed MMF (n = 6) and pseudolymphoma (n = 1) with pathognomic basophilic large macrophage infiltration, which had distinctive spiculated inclusions on electron microscopy. The intracytoplasmic aluminium was positive for PAS and Morin stains. Distinctive pathology and ultrastructure suggested an association with aluminium hydroxide-containing vaccines. To avoid misdiagnosis and mistreatment, we must further investigate this uncommon condition, and pharmaceutical companies should attempt to formulate better adjuvants that do not cause such adverse effects.

Thrombospondin-1 mediates muscle damage in brachio-cervical inflammatory myopathy and systemic sclerosis.

OBJECTIVE: To describe the clinical, serologic and histologic features of a cohort of patients with brachio-cervical inflammatory myopathy (BCIM) associated with systemic sclerosis (SSc) and unravel disease-specific pathophysiologic mechanisms occurring in these patients. METHODS: We reviewed clinical, immunologic, muscle MRI, nailfold videocapillaroscopy, muscle biopsy, and response to treatment data from 8 patients with BCIM-SSc. We compared cytokine profiles between patients with BCIM-SSc and SSc without muscle involvement and controls. We analyzed the effect of the deregulated cytokines in vitro (fibroblasts, endothelial cells, and muscle cells) and in vivo. RESULTS: All patients with BCIM-SSc presented with muscle weakness involving cervical and proximal muscles of the upper limbs plus Raynaud syndrome, telangiectasia and/or sclerodactilia, hypotonia of the esophagus, and interstitial lung disease. Immunosuppressive treatment stopped the progression of the disease. Muscle biopsy showed pathologic changes including the presence of necrotic fibers, fibrosis, and reduced capillary number and size. Cytokines involved in inflammation, angiogenesis, and fibrosis were deregulated. Thrombospondin-1 (TSP-1), which participates in all these 3 processes, was upregulated in patients with BCIM-SSc. In vitro, TSP-1 and serum of patients with BCIM-SSc promoted proliferation and upregulation of collagen, fibronectin, and transforming growth factor beta in fibroblasts. TSP-1 disrupted vascular network, decreased muscle differentiation, and promoted hypotrophic myotubes. In vivo, TSP-1 increased fibrotic tissue and profibrotic macrophage infiltration in the muscle. CONCLUSIONS: Patients with SSc may present with a clinically and pathologically distinct myopathy. A prompt and correct diagnosis has important implications for treatment. Finally, TSP-1 may participate in the pathologic changes observed in muscle.

Anti-hydroxy-3-methylglutaryl-coenzyme A reductase (anti-HMGCR) antibody in necrotizing myopathy: treatment outcomes, cancer risk, and role of autoantibody level.

Objective: To evaluate clinical associations of anti-hydroxy-3-methylglutaryl-coenzyme A reductase (anti-HMGCR) antibody (Ab) and statin exposure in necrotizing myopathy (NM) patients. Methods: NM without a known myositis-specific autoantibody (MSA) was ascertained from a large single-centre myositis database between 1985 and 2012. A comparison NM cohort included 32 anti-SRP+ autoantibody patients, and other control groups included 74 non-NM myositis patients and 21 non-myositis controls. Sera from all cases and controls were tested using a validated anti-HMGCR enzyme-linked immunosorbent assay. Clinical features including statin use and anti-HMGCR Ab status were compared between cases and controls. Results: Of the 256 NM muscle biopsies reviewed, only 48 subjects with available sera were identified as traditional MSA-negative NM. Anti-HMGCR positivity was significantly (p < 0.001) associated with MSA-negative NM [48% (23/48)] compared to all of the myositis and non-myositis controls [5% (6/127)]. Most anti-HMGCR Ab-positive NM patients had high titres of anti-HMGCR (83%) and a history of statin exposure (78%), along with severe muscle weakness, high creatine kinase (CK) levels (90% ≥ 5000 IU/L), a paucity of other organ manifestations, and the need for immunosuppression with prednisone and methotrexate, but generally favourable outcomes. Anti-HMGCR serum levels were associated with baseline CK levels but not muscle weakness. Conclusion: HMGCR Ab-positive NM patients are associated with statin exposure, have severe muscle weakness and high CK at presentation, lack other organ manifestations, and generally have favourable outcomes from immunosuppression. Anti-HMGCR Abs should be assessed in MSA-negative NM patients, particularly those with a history of statin exposure.

Fulminant Guillain-Barré syndrome showing severe pharyngeal-cervical-brachial weakness in the recovery phase: a case report.

BACKGROUND: Fulminant Guillain-Barré syndrome (GBS) is characterized clinically by rapid progression of severe symptoms, such as the absence of brainstem reflexes, complete tetraplegia and respiratory arrest. The clinical course of fulminant GBS remains unclear. Here, we report a patient with fulminant GBS, who showed severe weakness of the pharyngeal-cervical-branchial (PCB) area in the recovery phase. CASE PRESENTATION: A 38-year-old man rapidly developed fulminant GBS. In blood examination, he was positive for a broad range of anti-ganglioside antibodies, including anti-GQ1b, GT1a, GT1b, GD1a, GD1b and GD3 IgG antibodies. We performed immunosuppressive therapies using intravenous immunoglobulin and intravenous methylprednisolone. Although disturbance of consciousness and weakness of the distal upper and lower limbs improved gradually, weakness of the oropharynx, neck, and proximal upper limbs were resistant to these therapies. Anti-GT1a IgG antibodies remained persistently positive. Consequently, mechanical ventilation and tube feeding were required for 7 and 10 months, respectively. Two years later, weakness of the proximal upper limbs and mild respiratory dysfunction remained as sequelae. CONCLUSION: Anti-GT1a IgG antibodies are known to be detected in patients with the PCB variant of GBS. In fulminant GBS, the persistent presence of anti-GT1a IgG antibodies may be associated with occurrence of severe PCB-like weakness in the recovery phase.

Cognitive dysfunction in mice with passively induced MuSK antibody seropositive myasthenia gravis.

Recent reports on cognitive dysfunction, in addition to skeletal muscle fatigue, in muscle-specific tyrosine kinase antibody seropositive (MuSK+) myasthenia gravis (MG) patients led us to study cognition in mice with MuSK+ passive transfer MG (PTMG). Twelve 7-week-old female wild-type C57BL/6J mice were passively immunized with IgG from MuSK+ MG patients and 12 control mice received intraperitoneal saline injections. Mice were evaluated with clinical, neurophysiological and behavioral tests (Barnes maze (BM) and novel object recognition (NOR)), and the muscles were immunostained to evaluate the neuromuscular junction in the end of the study. Two-thirds of the immunized mice developed clinically distinct MuSK+ PTMG. MuSK+ PTMG mice spent less time exploring the novel object in the NOR test (MuSK+ mice 36.4% ±â€¯14.0 vs controls 52.4% ±â€¯13.0, p = .02), unrelated to the muscle weakness and regardless of rodents' innate preference of novelty. In the BM test, control mice were more eager to use the direct strategy than the MuSK+ mice (MuSK+ 17.3% vs controls 29.5%, p = .02). Our findings shed new light on cognition dysfunction in human MuSK+ MG patients and indicate that recognition memory in the perirhinal cortex could be affected in MuSK+ MG.

Anti-HMGCR antibody-associated necrotising myopathy and its association with statin use.

A 66-year-old man presented with chest pain and a 1-year history of generalised weakness, accompanied with generalised aches and pains. Symptoms worsened when he was initiated on statins. Investigations yielded high creatine kinase, high HMG-coenzymeA reductase (HMGCR) antibody titre, myopathic features on electromyography and muscle biopsy, and muscle atrophy on MRI. These results were in keeping with anti-HMGCR antibody myopathy. The patient responded well to immunosuppressive therapy.

Late-onset Myasthenia Gravis Accompanied by Amyotrophic Lateral Sclerosis with Antibodies against the Acetylcholine Receptor and Low-density Lipoprotein Receptor-related Protein 4.

An 82-year-old woman developed neck weakness and dysarthria with antibodies against acetylcholine receptor (AChR) and low-density lipoprotein receptor-related protein 4 (LRP4). Myasthenia gravis (MG) was diagnosed by edrophonium and repetitive nerve stimulation tests. Her symptoms resolved completely by immunotherapy. One year later, she presented with muscle weakness and bulbar palsy accompanied by atrophy and fasciculation. Her tendon reflexes were brisk, and Babinski's sign was positive. She was diagnosed with probable amyotrophic lateral sclerosis (ALS). Immunotherapy did not improve her symptoms, and she ultimately died of respiratory failure. MG and ALS may share a pathophysiology, including anti-LRP4 antibodies at the neuromuscular junction.

Pathogenic Mechanisms and Clinical Correlations in Autoimmune Myasthenic Syndromes.

Autoimmune myasthenic syndromes are antibody-mediated disorders of the neuromuscular junction. Common antigenic targets are the acetylcholine receptor or muscle specific kinase (MuSK) in myasthenia gravis (MG) and the voltage-gated calcium channel in Lambert-Eaton myasthenic syndrome. There is evidence that antibodies directed against other antigens such as low-density lipoprotein receptor-related protein 4 (LRP4) are also involved in MG. The mechanisms by which various antibodies exert their pathogenic effect depend on the IgG subclass and also the epitope location on the antigens. These mechanisms are partly heterogeneous and include antigen degradation, complement activation, direct functional blocking, or disruption of protein-protein interactions. The neuromuscular junction is characterized by a structural and functional plasticity that is able to compensate for some of the neuromuscular junction defects. Here, we discuss the underlying pathogenic mechanisms of the different autoantibodies and correlate them with phenotypic features. The understanding of these elements should help guide the clinical management of patients with autoimmune myasthenic syndromes.

Increased intracranial pressure in Guillain-Barré syndrome: A case report.

RATIONALE: Guillain-Barré syndrome (GBS) is an inflammatory autoimmune demyelinating polyneuropathy that affects most of the peripheral nervous system. Papilledema and raised intracranial pressure (ICP) are seen in some patients, and are thought to be associated with elevated cerebrospinal fluid (CSF) protein-though CSF protein levels are normal in some patients, thus the specific mechanisms remain unclear. Interleukin (IL)-17 levels are elevated in the CSF and plasma in GBS patients, and elevated IL-17 in the CSF of patients with idiopathic intracranial hypertension has been reported. Intravenous immunoglobulin (IVIG) exerts therapeutic effects by downregulating IL-17 in GBS patients. PATIENT CONCERNS: Herein we describe a case of a 14-year-old girl who initially presented with relapsing limb weakness. DIAGNOSES: Magnetic resonance imaging revealed an enlarged ventricle, electromyography, and nerve conduction studies were suggestive of polyradiculopathy, and lumbar puncture revealed elevated ICP with normal cells and elevated protein values. INTERVENTIONS: She was treated with IVIG 0.4 g/kg per day for 5 days. OUTCOMES: At a 6-month follow-up there had been no recurrence. LESSONS SUBSECTIONS: In GBS patients who have a relapsing course and develop papilledema with possible immunological disturbance, an accurate early diagnosis in conjunction with the prompt initiation of immunotherapy may improve clinical symptoms and the prognosis.

Clinico-serologic features of statin-induced necrotising autoimmune myopathy in a single-centre cohort.

Statin-induced necrotising autoimmune myopathy (NAM) is a rare but disabling complication of statin therapy. Data regarding treatment and outcomes in these patients is sparse. We retrospectively identified those patients with a diagnosis of statin-induced NAM who were managed in a single-tertiary referral centre from January 2014 to January 2017. Data regarding clinical features, serology, antibody status and functional outcome was collected. We identified 16 patients diagnosed with statin-induced NAM. Truncal weakness was present in 9/16 patients, of which one patient presented with camptocormia. Following treatment, the mean improvement in the 8-point manual muscle test (MMT8) score was 11 points (range 1-25). Antibodies to 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCR) were detected in 8/14 patients tested. Of patients who were HMGCR positive, 7/8 had significant truncal weakness, compared with 1/6 who were anti-HMGCR negative. In 4/7 patients who had anti-HMGCR retested following treatment, these antibodies subsequently became undetectable. The disappearance of anti-HMGCR was accompanied by sustained clinical improvement in all four patients. The mean Karnofsky Performance Status (KPS) prior to diagnosis was 89/100, and at latest follow-up had fallen to 68/100. We report a novel association of anti-HMGCR antibodies with truncal weakness in patients with statin-induced NAM. Functional impairments persist despite normalisation of muscle strength. Anti-HMGCR antibodies may disappear with treatment, paralleled by clinical remission of disease. Further prospective clinical trials are needed to determine optimal management strategies for statin-induced NAM.

Less Limb Muscle Involvement in Myositis Patients with Anti-Mitochondrial Antibodies.

Recent studies have revealed the clinical, histological, and pathophysiological characteristics in a group of inflammatory myopathies with selected autoantibodies. We retrospectively compared the clinical manifestations and histological features between 8 anti-mitochondrial (anti-M2) antibody-positive and 33 antibody-negative patients. Patients with anti-M2 antibodies have been previously reported to have delayed diagnostic confirmation and frequent cardiopulmonary complications in comparison to those without the antibodies. In our study, clinical characteristics in patients with the antibodies were as follows: lesser degree of limb muscle weakness and atrophy as well as lymphocytic infiltration in muscle biopsy specimens, and frequent paravertebral muscle atrophy. Anti-M2 antibody appeared to be a biomarker related to not only cardiopulmonary complications, but also characteristic -distributions of affected muscles.

Decreased bone mineral density in experimental myasthenia gravis in C57BL/6 mice.

Experimental autoimmune myasthenia gravis (EAMG), an animal model of myasthenia gravis (MG), can be induced in C57BL/6 (B6, H-2 b) mice by 2-3 injections with Torpedo californica AChR (tAChR) in complete Freund's adjuvant. Some EAMG mice exhibit weight loss with muscle weakness. The loss in body weight, which is closely associated with bone structure, is particularly evident in EAMG mice with severe muscle weakness. However, the relationship between muscle weakness and bone loss in EAMG has not been studied before. Recent investigations on bone have shed light on association of bone health and immunological states. It is possible that muscle weakness in EAMG developed by anti-tAChR immune responses might accompany bone loss. We determined whether reduced muscle strength associates with decreased bone mineral density (BMD) in EAMG mice. EAMG was induced by two injections at 4-week interval of tAChR and adjuvants in two different age groups. The first tAChR injection was either at age 8 weeks or at 15 weeks. We measured BMD at three skeletal sites, including femur, tibia, and lumbar vertebrae, using dual energy X-ray absorptiometry. Among these bone areas, femur of EAMG mice in both age groups showed a significant decrease in BMD compared to control adjuvant-injected and to non-immunized mice. Reduction in BMD in induced EAMG at a later-age appears to parallel the severity of the disease. The results indicate that anti-tAChR autoimmune response alone can reduce bone density in EAMG mice. BMD reduction was also observed in adjuvant-injected mice in comparison to normal un-injected mice, suggesting that BMD decrease can occur even when muscle activity is normal. Decreased BMD observed in both tAChR-injected and adjuvant-injected mice groups were discussed in relation to innate immunity and bone-related immunology involving activated T cells and tumour necrosis factor-related cytokines that trigger osteoclastogenesis and bone loss.

Hyperacute muscle weakness in an unusual coexistence of antisignal recognition particle and anti-Mi-2 antibodies.

Idiopathic inflammatory myopathies are a heterogeneous group of systemic diseases characterised by variable phenotypes of chronic progressive muscle weakness. Myositis-specific antibodies (MSAs) include antibodies to cytoplasmic signal recognition particle (SRP) and various tRNA synthetases as well as the nuclear helicase protein Mi-2. These antibodies are typically found only in a fraction of true myositis cases and they tend to be mutually exclusive. Few cases of coexistence of two MSAs in the same patient have been reported and these cases all involve an antisynthetase antibody coexisting with either anti-SRP or anti-Mi-2 antibody. Peculiar clinical manifestations may be associated with different combinations of MSAs but the rarity of these cases makes their characterisation difficult. We report the first ever case of anti-SRP and anti-Mi-2 copositive polymyositis in a 19-year-old boy who presented with a week history of profound muscle weakness that attained its peak within 24 hours of onset.

Rapamycin alleviates inflammation and muscle weakness, while altering the Treg/Th17 balance in a rat model of myasthenia gravis.

Myasthenia gravis (MG) is an autoimmune disease commonly treated with immunosuppressants. We evaluated the novel immunosuppressant, rapamycin (RAPA), in a rat model of experimental autoimmune MG (EAMG). Mortality rates in the RAPA (12%) were significantly down compared with the EAMG (88%) or cyclophosphamide (CTX) (68%) intervention groups. Muscular weakness decreased after both RAPA and CTX treatment. However, Lennon scores were lower (1.74 ± 0.49, 3.39 ± 0.21, and 3.81 ± 0.22 in RAPA, CTX, and EAMG groups, respectively), and body weights (203.12 ± 4.13 g, 179.23 ± 2.13 g, and 180.13 ± 5.13 g in RAPA, CTX, and EAMG groups, respectively) were significantly higher, only in the RAPA group. The proportion of regulatory T cells (Treg) significantly increased, while that of Th17 cells significantly decreased in the RAPA group compared with the EAMG group. In comparison, CTX intervention resulted in increased Th17 but significantly decreased Tregs. Hence, RAPA can be more effectively used in comparison with CTX to treat MG, with an efficacy higher than that of CTX. In addition, our results suggest RAPA's efficacy in alleviating symptoms of MG stems from its ability to correct the Treg/Th17 imbalance observed in MG.

Resistance exercise attenuates skeletal muscle oxidative stress, systemic pro-inflammatory state, and cachexia in Walker-256 tumor-bearing rats.

The aim of this study was to investigate the effects of resistance exercise training (RET) on oxidative stress, systemic inflammatory markers, and muscle wasting in Walker-256 tumor-bearing rats. Male (Wistar) rats were divided into 4 groups: sedentary controls (n = 9), tumor-bearing (n = 9), exercised (n = 9), and tumor-bearing exercised (n = 10). Exercised and tumor-bearing exercised rats were exposed to resistance exercise of climbing a ladder apparatus with weights tied to their tails for 6 weeks. The physical activity of control and tumor-bearing rats was confined to the space of the cage. After this period, tumor-bearing and tumor-bearing exercised animals were inoculated subcutaneously with Walker-256 tumor cells (11.0 × 107 cells in 0.5 mL of phosphate-buffered saline) while control and exercised rats were injected with vehicle. Following inoculation, rats maintained resistance exercise training (exercised and tumor-bearing exercised) or sedentary behavior (control and tumor-bearing) for 12 more days, after which they were euthanized. Results showed muscle wasting in the tumor-bearing group, with body weight loss, increased systemic leukocytes, and inflammatory interleukins as well as muscular oxidative stress and reduced mTOR signaling. In contrast, RET in the tumor-bearing exercised group was able to mitigate the reduced body weight and muscle wasting with the attenuation of muscle oxidative stress and systemic inflammatory markers. RET also prevented loss of muscle strength associated with tumor development. RET, however, did not prevent the muscle proteolysis signaling via FBXO32 gene messenger RNA expression in the tumor-bearing group. In conclusion, RET performed prior tumor implantation prevents cachexia development by attenuating tumor-induced systemic pro-inflammatory condition with muscle oxidative stress and muscle damage.