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

Abstract

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.

Idiopathic inflammatory myopathies with anti-mitochondrial antibodies: Clinical features and treatment outcomes in a Chinese cohort

“…In our study, the prevalence of AMAs in IIM patients was 5.15%, which is similar to that reported in France (7.80%) but quite higher than that reported in America (0.6%) and lower than that reported in Japan (11.3-19.5%) [3][4][5][6] . Although the Bohan and Peter inclusion criteria of low specificity used in the American research may partly explain the reason for our relatively higher AMA prevalence than that in America, there is still conspicuous heterogeneity in the prevalence of AMAs [19] .…”

“…Firstly, although AMAs only occurred in adult IIM patients, the age at onset ranged from 23 years to 86 years and the mean age at onset ranged from the fourth decade to the seventh decade [3][4][5]7,8,[20][21][22][23][24][25][26] . Besides, the average disease duration varied from 10 months (in our study) to 6.5 years, and the prevalence of chronic disease duration varied from approximately 30% (in our study) to 85% [3,5,6] . In fact, although AMAs are regarded as the serological hallmarks of PBC, they are not always associated with PBC in IIM patients.…”

“…Furthermore, Takeshi Uenaka reported that patients with AMAs have cardiac dysfunctions, longer disease duration, less degree of limb muscle weakness and sparse lymphocytic infiltration than those without AMAs. However, AMA-associated IIMs did not seem to be associated with cardiac involvement, muscular atrophy or a particular pathological feature in a European cohort as reported by Benveniste [3][4][5][6] .…”

“…In fact, although AMAs are regarded as the serological hallmarks of PBC, they are not always associated with PBC in IIM patients. Specifically, the frequency of PBC ranged largely from 15-75% [3][4][5][6] . The frequency of cardiac involvement is relatively higher in AMA-associated IIM [3,5,6,11,17,27] .…”

“…Specifically, the frequency of PBC ranged largely from 15-75% [3][4][5][6] . The frequency of cardiac involvement is relatively higher in AMA-associated IIM [3,5,6,11,17,27] . This may be partly due to the presence of PBC because it is associated with increased cardiovascular disease risk [3,[28][29][30] .…”