Tumor necrosis factor-alpha expression in muscles of polymyositis and dermatomyositis.
We evaluated the expression of tumor necrosis factor-alpha (TNF-alpha) mRNA in muscle biopsy specimens from patients with polymyositis (PM) and dermatomyositis (DM) to clarify its role in the pathogenesis of PM and DM. We performed non-radioactive in situ hybridization studies for TNF-alpha combined with immunohistochemistry for cell type-specific markers on muscles from ten PM and five DM patients. TNF-alpha-positive infiltrating cells present in the endomysium and perimysium were found in all PM and DM muscles. The frequency of TNF-alpha-positive cells against total infiltrating cells was similar among PM and DM (27.1 +/- 7.4% in PM and 28.5 +/- 13.6% in DM). However, TNF-alpha/CD8-positive lymphocytes and TNF-alpha-positive macrophages invading the non-necrotic muscle fiber were observed only in PM but not in DM. TNF-alpha was more highly expressed in PM and DM than was previously thought, and it was suggested that TNF-alpha plays a role in muscle fiber degeneration in PM.
Kuru
S
S
Department of Neurology, Nagoya University School of Medicine, Japan.
Inukai
A
A
Liang
Y
Y
Doyu
M
M
Takano
A
A
Sobue
G
G
D000368:Aged; D001706:Biopsy; D003882:Dermatomyositis / Q000473:pathology* / Q000503:physiopathology; D005260:Female; D015870:Gene Expression; D006801:Humans; D017403:In Situ Hybridization; D008297:Male; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000473:pathology; D018482:Muscle, Skeletal / Q000473:pathology* / Q000502:physiology; D012333:RNA, Messenger / Q000032:analysis; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*
D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha