Parasitic infections and myositis. Parasitol Res. 2012;110:1-18. [PMID: 21881948 DOI: 10.1007/s00436-011-2609-8]

The Role of Environmental Factors in the Development of Idiopathic Inflammatory Myopathies: a Narrative Review

PURPOSE OF REVIEW

This review aims to evaluate recent findings on the role of environmental factors in the development and clinical presentation of idiopathic inflammatory myopathies (IIMs).

RECENT FINDINGS

A targeted literature review was conducted to identify reports relevant to the association between environmental factors and IIMs published over the past three years. There has been an increasing number of publications dealing with the association of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection or vaccination with the development of IIMs, highlighting the significant role of the antiviral immune response in the pathogenesis of the disease. Traditional environmental factors associated with the pathogenic process of IIM subclassifications included drugs such as statins and immune checkpoint inhibitors, ultraviolet radiation, smoking, air pollutants, and vitamin D deficiency. Correlations of seasonality and residence with the onset of certain IIM subtypes suggest a potential role of environmental triggers in the pathogenic process. An interplay between genetic predisposition and various environmental factors might contribute to the development of IIMs as well as the heterogeneous clinical and serological presentation of IIMs. The growing evidence on the role of environmental factors in the development of IIMs provides important clues to elucidate the pathophysiology of these disease entities. The mechanisms underlying the interactions between genetic predisposition and environmental factors should be investigated in the future.

Stem cell biotherapy: A new remedy for Trichinella spiralis-induced inflammatory myopathy

Trichinella spiralis (T. spiralis)-induced myopathy is an inflammatory myopathy that is difficult to treat unless the parasite is combated in its early intestinal phase before it reaches the muscles. This study aimed to evaluate the effect of local mesenchymal stem cell (MSC) therapy on T. spiralis-induced inflammatory myopathy in rats. Rats were divided into four groups: Group 1 (non-infected non-treated group); Group 2 (infected non-treated group); Group 3 (infected albendazole (ABZ)-treated group); and Group 4 (infected MSC-treated group). Their muscle status was assessed physiologically with the righting reflex and electromyography (EMG), parasitologically with the total muscle larval count, histopathologically with hematoxylin and eosin and Mallory's trichrome stains, as well as immunohistochemically for myogenin as a marker of muscle regeneration. Additionally, serum muscle enzymes creatine kinase (CK) and lactate dehydrogenase (LDH), as well as muscle matrix metalloproteinases MMP1 and MMP9, were assayed. Finally, the immunological response was assessed by measuring the levels of the muscle inflammatory cytokines tumor necrosis factor-alpha (TNF-α), interferon-gamma (INF-γ), and interleukin-4 (IL-4). Our findings revealed that MSC therapy markedly improved muscle EMG and righting reflex, as well as the histopathological appearance of the muscles, reduced inflammatory cellular infiltrates, and increased myogenin immunostaining. It also reduced serum CK and LDH levels, as well as muscle INF-γ, TNF-α, IL-4, MMP1, and MMP9 levels. However, it had no effect on the total muscle larval count. Accordingly, due to its anti-inflammatory properties and muscle-regenerative effect, MSC therapy could be a promising new remedy for T. spiralis-induced myopathy.

Idiopathic eosinophilic myositis: a systematic literature review

Eosinophilic myositis belong to the idiopathic inflammatory myopathies and are defined by an inflammatory infiltrate composed of eosinophils within the muscle. To date, no consensus exists for diagnosis and care of such patients. The aim of this review was to describe clinical and histological presentation, treatment, and outcome of eosinophilic myositis based on a systematic review of all published histologically proven cases of eosinophilic myositis. A total of 453 records were identified in MEDLINE until November 2020. A total of 69 published cases were identified. The analysis of these allowed the distinction of the 3 previously described pathological subtypes: focal eosinophilic myositis (n = 17); diffuse eosinophilic myositis (n = 36); and eosinophilic perimyositis (n = 16). We propose a simple algorithm for diagnosis and treatment strategy for the care of patient with muscular symptoms and blood eosinophilia. This work also highlights eosinophilic myositis pathogenesis and the need for careful investigations in order to rule out differential diagnoses.

Cutaneous myiasis with eosinophilic pleural effusion: A case report

BACKGROUND

Cutaneous myiasis is frequently observed; however, eosinophilic pleural effusion induced by this condition is rare.

CASE SUMMARY

We report the case of a 65-year-old female Tibetan patient from Qinghai Province, who presented to West China Hospital of Sichuan University around mid-November 2011 with a chief complaint of recurrent cough, occasional hemoptysis, and right chest pain. There was no past medical and surgical history of note, except for occasional dietary habit of eating raw meat. Clinical examination revealed a left lung collapse and diminished breathing sounds in her left lung, with moist rales heard in both lungs. Chest X-rays demonstrated a left hydropneumothorax and a right lung infection. Chest computed tomography revealed a left hydropneumothorax with partial compressive atelectasis and patchy consolidation on the right lung. Laboratory data revealed peripheral blood eosinophilia of 37.2%, with a white blood cell count of 10.4 × 10⁹/L. Serum immunoglobulin E levels were elevated (1650 unit/mL). Serum parasite antibodies were negative except for cysticercosis immunoglobulin G. Bone marrow aspirates were hypercellular, with a marked increase in the number of mature eosinophils and eosinophilic myelocytes. An ultrasound-guided left-sided thoracentesis produced a yellow-cloudy exudative fluid. Failure to respond to antibiotic treatment during hospitalization for her symptoms and persistent blood eosinophilia led the team to start oral albendazole (400 mg/d) for presumed parasitic infestation for three consecutive days after the ninth day of hospitalization. Intermittent migratory stabbing pain and swelling sensation on both her upper arms and shoulders were reported; tender nodules and worm-like live organisms were observed in the responding sites 1 wk later. After the removal of the live organisms, they were subsequently identified as first stage hypodermal larvae by the Sichuan Institute of Parasites. The patient’s symptoms were relieved soon afterwards. Telephonic follow-up 1 mo later indicated that the blood eosinophilia and pleural effusion were resolved.

CONCLUSION

Eosinophilic pleural fluid can be present in a wide array of disorders. Myiasis should be an important consideration for the differential diagnosis when eosinophilic pleural effusion with blood eosinophilia is observed.

Infective myositis

Myositis is inflammation especially of the voluntary muscles, characterized by localized or diffuse pain, tenderness on movement or palpation, swelling, and/or weakness. The two main categories of myositis include non-infectious and infectious. Infective myositis may be due to a wide variety of pathogens, including bacteria, fungi, viruses, and parasites. A brief account of the various pathogens causing infective myositis is discussed.

Eosinophilic granulomatosis with polyangiitis presenting with myositis: case based review

Eosinophilic granulomatosis with polyangitis (EGPA) is a systemic necrotizing small-vessel vasculitis that presents heterogeneously as a multi-organ disease. EGPA evolves through three phases: (1) prodromic phase with asthma, atopy and sinusitis, (2) eosinophilic phase characterized by peripheral eosinophilia and eosinophilic infiltration without necrosis, and (3) vasculitic phase involving organ damage. EGPA often presents with asthma, mononeuritis multiplex, lung infiltrates, sinusitis and constitutional symptoms. Although myalgias are common, EGPA rarely presents with true weakness with elevated creatinine kinase (CK). We describe a rare case of a patient presenting with eosinophilic myositis, who subsequently developed fulminant EGPA. The patient's diagnosis was supported by an initial clinical presentation of weakness and elevated CK, followed by fleeting pulmonary infiltrates and mononeuritis multiplex, peripheral eosinophilia, and strongly positive myeloperoxidase anti-cytoplasmic antibody (MPO-ANCA). Muscle biopsy revealed eosinophilic myositis. The patient responded well to high-dose glucocorticoids and cyclophosphamide with improved symptoms and biochemical markers. Based on our literature review, there are only seven similar cases reported of EGPA presenting with myositis and confirmatory muscle biopsies. There is significant heterogeneity in their clinical findings, histopathology and treatments that were used. Our case report and literature review highlights the importance of recognizing myositis as an initial presenting symptom of EGPA, providing an opportunity for early diagnosis and treatment to reduce risk of further disease progression and morbidity.

[Infectious myositis]

Infectious myositis is a rare condition that can be caused by bacteria, viruses, parasites or fungi. Muscle pain or weakness are symptoms shared by all type of myositis. Diagnosis is made on clinical presentation: fever and poor general state is found in bacterial myositis, diffuse muscle pain with flu-like symptoms in viral causes, eosinophilia and a tropical travel history can be related to parasitic etiology, and immunocompromising condition suggests fungal infection. Rhabdomyolysis, leukocytosis and elevated C-reactive protein are common. Imaging (computed tomography or magnetic resonance imaging) can be useful to detect which muscle is affected. The causative organism can be identified on blood cultures, skeletal muscle biopsy, serology or any other pathogen specific test. Treatment depends on the causative organism. Open surgical or imaging-guided drainage is usually necessary in bacterial myositis.

Prevalence of Toxoplasma gondii and Toxocara canis Among Myositis Patients in the Southwest of Iran

INTRODUCTION

Parasitic myositis is caused by some parasites, such as Toxoplasma gondii) T. gondii (and Toxocara canis (T. canis). So, the aim of the study was to evaluate the prevalence T. gondii and T. canis in patients with myositis and healthy individuals.

METHODS

A total of 108 samples were randomly selected as the control (54 healthy individuals) and test (54 myositis patients) groups. IgG and IgM antibodies (Ab) against T. gondii and IgG Ab against T. canis were measured by the enzyme-linked immunosorbent assay (ELISA). The detection of chronic and acute toxoplasmosis was performed by the ELISA IgG avidity. The presence of T. gondii in the blood was evaluated using the nested polymerase chain reaction (nested-PCR).

RESULTS

Of 108, 33 (30.6%) cases were positive for IgG against T. gondii that 19 (35.2%) and 14 (25.9%) were observed in myositis patients and healthy individuals, respectively (P=0.296). Of 19 positive cases, 12 (63.2%) and 7 (36.8%) cases were detected as chronic and acute toxoplasmosis, respectively, while, all positive cases in the control group had chronic toxoplasmosis (P=0.013). One (1.9%) sample was positive for anti- T. gondii IgM and two (3.7%) samples were positive for IgG against T. canis by the ELISA that these positive cases were observed only in myositis patients (P=1.000 P=0.495, respectively). B1 T. gondii gene was amplified in 12 (63.2%) and 1 (7.1%) in myositis patients and healthy subjects (P=0.001).

CONCLUSION

Our findings showed that there was a relatively high prevalence of acute toxoplasmosis in myositis patients in comparison with the control subjects in the Southwest of Iran.

Severe toxoplasmosis imported from tropical Africa in immunocompetent patients: A case series

BACKGROUND

Toxoplasmosis is a zoonosis caused by the protozoan Toxoplasma gondii. In immunocompetent patients the infection is usually benign. However, cases of severe and even lethal primo-infections are regularly reported in South America. In contrast, data from tropical Africa are fragmentary.

METHODS

Data for French cases of severe toxoplasmosis acquired between 2013 and 2018, in tropical Africa and among immunocompetent patients were collected retrospectively in 2018.

RESULTS

Four male patients with a mean age of 34-years were identified. All infections originated in West or Central Africa. The clinical presentations were heterogeneous: two patients had severe disseminated toxoplasmosis, of which one presented with chorioretinitis associated with myositis and the other with febrile pneumopathy; one patient presented with post-infectious acute cerebellar ataxia and the final case had general symptoms and skin manifestations. The diagnosis of acute toxoplasmosis was confirmed by serology in four patients. Molecular diagnosis confirmed T. gondii infection in three patients with Africa 1 as the dominant genotype. The infection was cured with anti-infective treatment in all four patients. Ocular sequelae were reported in the two patients with chorioretinitis.

CONCLUSIONS

Imported cases of severe toxoplasmosis in immunocompetent patients are rare in France. However, this aetiology should be evoked rapidly in a patient with a severe infectious syndrome who has recently visited or originated from tropical Africa.

Polyphasic Rhabdomyositis in California Sea Lions (Zalophus Californianus): Pathology and Potential Causes

A myositis syndrome has been recognized for more than a decade in California sea lions (CSLs; Zalophus californianus) but a detailed description of the lesions and potential causes of this condition is lacking. The tissues of 136 stranded CSLs with rhabdomyositis were examined. Rhabdomyositis was considered incidental in 67% (91/136) of the CSLs, and a factor contributing to the animal stranding (significant rhabdomyositis) in 33% (45/136). Of the 91 cases with incidental rhabdomyositis, lesions consisted of a few small foci of lymphohistiocytic inflammation. Of the 45 cases with significant rhabdomyositis, 28 (62%) also presented with major comorbidities such as leptospirosis (2 animals) and domoic acid toxicosis (6 animals), whereas 17 (38%) had severe polyphasic rhabdomyositis as the only major disease process associated with mortality. In these animals, most striated muscles had multiple white streaks and diffuse atrophy. Microscopically, there was myofiber necrosis surrounded by lymphocytes and histiocytes admixed with areas of myofiber regeneration, and/or moderate to severe rhabdomyocyte atrophy usually adjacent to intact Sarcocystis neurona cysts. At the interface of affected and normal muscle, occasional T lymphocytes infiltrated the sarcoplasm of intact myocytes, and occasional myofibers expressed MHCII proteins in the sarcoplasm. S. neurona antibody titers and cyst burden were higher in animals with significant polymyositis antibody titers of (26125 ± 2164, 4.5 ± 1.2 cysts per section) and active myonecrosis than animals with incidental rhabdomyositis antibody titers of (7612 ± 1042, 1.7 ± 0.82 cysts per section). The presented findings suggest that S. neurona infection and immune-mediated mechanisms could be associated with significant polyphasic rhabdomyositis in CSLs.

Therapeutic administration of IL-10 and amphiregulin alleviates chronic skeletal muscle inflammation and damage induced by infection

Maintenance of tissue integrity in skeletal muscle requires the immunomodulatory and regenerative functions of muscle-resident regulatory T cells (Tregs). Chronic skeletal muscle infections, such as with Toxoplasma gondii disrupt normal immuno-regulatory networks and lead to pathogenic changes in Treg function. Specifically, Tregs during chronic T. gondii infection reinforce an inflammatory macrophage bias that exacerbates injury in skeletal muscle. In this study, we investigated whether the aberrations in skeletal muscle Treg function during chronic infection could be overcome by treatment with Treg-related factors associated with enhanced muscle regeneration during sterile injury. We show treatment of chronically infected mice with the Treg promoting therapies, interleukin-2 complexed with anti-IL-2 antibody or interleukin-33 (IL-33), did not restore macrophage dynamics or muscle function, respectively, in vivo. However supplementation of known Treg-derived factors, interleukin-10 (IL-10) and amphiregulin (Areg) improved muscle function and skewed macrophages toward a restorative phenotype in the presence of chronic infection. These shifts in macrophage phenotype are coupled with enhanced physiologic parameters of regeneration. Together, these data suggest that while Treg-mediated immuno-regulation is compromised during chronic skeletal muscle infection, supplementation of canonical Treg-derived factors such as IL-10 and Areg can restore immunologic balance and enhance muscle repair.

Severe Rhabdomyolysis without Systemic Involvement: A Rare Case of Idiopathic Eosinophilic Polymyositis

Introduction. Eosinophilic polymyositis (EPM) is a rare cause of rhabdomyolysis characterized by eosinophilic infiltrates in the muscle. We describe the case of a young patient with eosinophilic polymyositis causing isolated severe rhabdomyolysis without systemic involvement. Case Presentation. A 22-year-old Haitian female with no past medical history presented with progressive generalized muscle aches without precipitating factors. Examination of the extremities revealed diffuse muscle tenderness. Laboratory findings demonstrated peripheral eosinophilia and high creatinine phosphokinase (CPK) and transaminase levels. Workup for the common causes of rhabdomyolysis were negative. Her CPK continued to rise to greater than 100,000 units/L so a muscle biopsy was performed which showed widespread eosinophilic infiltrate consistent with eosinophilic polymyositis. She was started on high dose systemic corticosteroids with improvement of her symptoms, eosinophilia, and CPK level. Discussion. This case illustrates a systematic workup of rhabdomyolysis in the presence of peripheral eosinophilia. Many differential diagnoses must be considered before establishing a diagnosis of idiopathic eosinophilic polymyositis. To our knowledge, our case of eosinophilic polymyositis is unique as it presented with severe rhabdomyolysis without another organ involvement. Clinicians should maintain a high index of suspicion for this physically debilitating disease to aid in prompt diagnosis.

[New aspects on the pathogenesis of myositis]

Idiopathic inflammatory myopathies (IIM) are chronic inflammatory diseases of muscle characterized by proximal muscle weakness. There are three main groups of diseases, dermatomyositis, polymyositis and inclusion body myositis. The muscle tissue is invaded by the humoral autoantibody producing immune system (B-cells) and by the cellular immune system with autoaggressive and inflammation modulating cells (e.g. dendritic cells, monocytes/macrophages, CD4 + and CD8 + T-cells and natural killer cells). The presence of specific or associated autoantibodies and inflammatory cellular infiltrates with cytotoxic and immune autoreactive properties are characteristic for IIM diseases. The pathogenesis is still unknown; nevertheless, there are several hints that exogenic factors might be involved in initiation and disease progression and bacterial, fungal and viral infections are thought to be possible initiators. Up to now information on prognostic markers to help with decision-making for individual treatment are limited. In addition, there has been only limited therapeutic success including conventional or novel drugs and biologicals and comparative validation studies are needed using similar outcome measurements. Moreover, to facilitate the use and development of novel therapies, elaboration of intracellular and cell-specific regulation could be useful to understand the etiopathogenesis and allow a better diagnosis, prognosis and possibly also a prediction for individualized subgroup treatment.