Chemokine-like factor expression in the idiopathic inflammatory myopathies.
OBJECTIVE
We evaluated the expression of chemokine-like factor (CKLF) in biopsied muscle fibers in inflammatory myopathies, non-inflammatory myopathies and neurologically diseased controls.


METHODS
We studied the expression of CKLF in 15 polymyositis (PM), five dermatomyositis (DM), 15 non-inflammatory myopathies and nine neurologically diseased patients by immunohistochemistry.


RESULTS
Chemokine-like factor was mostly expressed in small diameter muscle fibers surrounded by infiltrated lymphocytes of inflammatory myopathies patients. Parts of them were also positive for the staining of the developmental form of myosin heavy chain, a maker of regenerating muscle fibers. Thrombin immunoreactivity was observed in endomysium in PM and perimysium in DM. In vitro differentiation study showed a constitutive expression of CKLF in myoblasts that was abolished in myotubes during differentiation process and was induced again by thrombin. Thrombin regulates CKLF expression through protease-activated receptor-1 in myotubes. Treatment of a protein kinase C inhibitor partially blocked CKLF expression in myoblasts, while it remarkably inhibited that in myotubes.


CONCLUSIONS
Chemokine-like factor expression is differentially regulated in myoblasts and myotubes. Thrombin could be a strong regulator for its expression. As CKLF is immunohistochemically positive in regenerating muscle fibers, we postulate here that CKLF is a useful marker for regenerating muscle fibers in inflammatory myopathies.
Chowdhury
M H
MH
Department of Internal Medicine III, Shimane University Faculty of Medicine, Shimane University Hospital, Izumo, Japan.
Nagai
A
A
Terashima
M
M
Sheikh
A
A
Murakawa
Y
Y
Kobayashi
S
S
Yamaguchi
S
S
D000368:Aged; D001706:Biopsy; D002478:Cells, Cultured; D018925:Chemokines / Q000235:genetics / Q000378:metabolism*; D003882:Dermatomyositis / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D015870:Gene Expression / Q000502:physiology; D006490:Hemostatics / Q000494:pharmacology; D006801:Humans; D007150:Immunohistochemistry; D062792:MARVEL Domain-Containing Proteins; D008297:Male; D008875:Middle Aged; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000473:pathology; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D032448:Myoblasts, Skeletal / Q000166:cytology / Q000378:metabolism; D017285:Polymyositis / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology*; D012038:Regeneration / Q000502:physiology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D019311:Staurosporine / Q000494:pharmacology; D013917:Thrombin / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology
C432676:CKLF protein, human; D018925:Chemokines; D004791:Enzyme Inhibitors; D006490:Hemostatics; D062792:MARVEL Domain-Containing Proteins; D013917:Thrombin; D019311:Staurosporine