Impaired redox status and cytochrome c oxidase deficiency in patients withpolymyalgia rheumatica

Objective-To evaluate redox status and muscular mitochondrial abnormalities in patients with polymyalgia rheumatica (PMR). Methods-Prospective evaluation of deltoid muscle biopsy in 15 patients with PMR. Fifteen subjects matched for age and sex, with histologically normal muscle and without clinical evidence of myopathy, were used as controls. Cr yostat sections of muscle were processed for conventional dyes, cytochrome c oxidase (COX), usual histochemical reactions, and Sudan black. A total of 300-800 fibres was examined in each case. Blood lactate, pyruvate, and lac tate/pyruvate ratio were determined in all patients. Results-Ragged red fibres were found in eight patients with PMR and account ed for 0-0.5% of fibres. Focal COX deficiency was found in 14 (93%) of 15 p atients and in nine (60%) of 15 controls. COX deficient fibres were more co mmon in patients with PMR (range 0-2.5%; mean 0.9%) than mi controls (range 0-1.2%; mean 0.3%) (paired t test, p=0.001). Seven (47%) of 15 patients ha d high blood lactate levels (1.50-2.60 mmol/l) or high blood lactate/ pyruv ate ratios (22-25). Conclusions-PMR is associated with mitochondrial abnormalities not solely r elated to the aging process.