Deltoid muscle in patients with polymyalgia rheumatica.
OBJECTIVE
To investigate muscle tissue in patients with polymyalgia rheumatica (PMR).


METHODS
Deltoid muscle biopsies obtained from 10 female patients with PMR before corticosteroid therapy and from 5 healthy female controls of similar age were studied using light microscopy. Serial cryosections were stained for the activity of myofibrillar ATPases at various pH and for oxidative and glycolytic enzymes. Sections were also incubated with antibodies against different myosin heavy chain (MyHC) isoforms, and the laminin alpha1 chain, identifying capillaries and cell borders, and against ligands for selected adhesion molecules.


RESULTS
The muscle fibers in patients and controls were mainly of type I containing slow MyHC, or type II AB containing both fast A and fast B MyHC isoforms. The oxidative capacity of the muscle fibers was in general low. In the patients with PMR the numbers of capillaries per unit area of type I and type II fibers were higher than in controls (p = 0.05 and p < 0.5, respectively). No accumulation of inflammatory cells or increased expression of adhesion molecules in the muscle sections from patients with PMR was found.


CONCLUSIONS
There is increased microvascularization of the deltoid muscle fibers in patients with PMR. Whether this is directly associated with the systemic inflammation and the musculoskeletal symptoms or is mainly due to muscle fiber atrophy could not be determined.
Department of Rheumatology, University Hospital of Northern Sweden, Umeå.
A
A
Uddhammar
S
S
Rantapää Dahlqvist
B
B
Hedberg
L E
LE
Thornell
D000368:Aged; D000369:Aged, 80 and over; D002196:Capillaries / Q000473:pathology; D015815:Cell Adhesion Molecules / Q000378:metabolism; D005260:Female; D006651:Histocytochemistry; D006801:Humans; D007150:Immunohistochemistry; D007249:Inflammation / Q000276:immunology; D007797:Laminin / Q000378:metabolism; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000098:blood supply / Q000201:enzymology / Q000276:immunology / Q000473:pathology*; D018995:Myosin Heavy Chains / Q000378:metabolism; D009243:NAD / Q000378:metabolism; D011111:Polymyalgia Rheumatica / Q000201:enzymology / Q000276:immunology / Q000473:pathology*; D012782:Shoulder
D015815:Cell Adhesion Molecules; D007797:Laminin; D009243:NAD; D018995:Myosin Heavy Chains