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To evaluate the possible role of cytokines in human immunodeficiency virus (HIV)-associated muscular disorders, we performed immunocytochemistry for interleukin-1 alpha, -1 beta, and -6 and tumor necrosis factor-alpha on frozen muscle biopsy specimens from HIV-infected patients with various myopathies (HIV polymyositis in 5, HIV-wasting syndrome in 5, zidovudine myopathy in 10) and from seronegative individuals (normal muscle in 2, mitochondrial cytopathies in 10). The HIV-infected patients showed positive reactivities in vessels (interleukin-1) and in inflammatory cells (mainly interleukin-1 and tumor necrosis factor-alpha), including perivascular hemosiderin-laden macrophages in 5 patients. In zidovudine myopathy, a majority of AZT fibers (i.e., ragged-red fibers with marked myofibrillar changes) showed mild to marked expression of interleukin-1. Expression of interleukin-1 in the other mitochondrial myopathies was much weaker. Interleukin-1 beta messenger RNA was demonstrated in muscle fibers by in situ hybridization, implying that interleukin-1 was produced in muscle cells. Immunoelectron microscopy showed that interleukin-1 alpha was mainly bound to mitochondrial membranes in AZT fibers. Proinflammatory and destructive effects of the studied cytokines might be responsible for several myopathological changes observed in HIV-infected patients, including inflammation and hemosiderin deposits in muscle tissue, and prominent myofibrillar breakdown in AZT fibers.

The use of zidovudine (AZT) for the treatment of acquired immunodeficiency syndrome (AIDS) induces a DNA-depleting mitochondrial myopathy, which is histologically characterized by the presence of muscle fibers with "ragged-red"-like features, red-rimmed or empty cracks, granular degeneration, and rods (AZT fibers). Because dysfunctioning muscle mitochondria may lead to defects of beta-oxidation of fatty acids, we examined the degree of neutral fat accumulation and muscle carnitine levels in the muscle biopsy specimens from 21 patients with AZT-induced myopathic symptoms of varying severity. Six patients with no AZT fibers had normal endomyofibrillar lipid deposits and muscle carnitine levels; 7 patients with fewer than 5 AZT fibers per field had a mild (+) to moderate (++) increase in lipid droplets, and reduced muscle carnitine levels (3 patients); and 8 patients with more than 5 AZT fibers had severe muscle changes, a ++ to marked ( ) increase in lipid droplets, and reduced muscle carnitine levels (6 patients). Serial sections showed lipid globules often within "cracks" or vacuoles of the abnormal muscle fibers. We conclude that the muscle mitochondrial impairment caused by AZT results in (1) accumulation of lipid within the muscle fibers owing to poor utilization of long-chain fatty acids, (2) reduction of muscle carnitine levels probably due to decreased carnitine uptake by the muscle, and (3) depletion of energy stores within the muscle fibers. The findings may have potential therapeutic implications in the treatment of AZT-induced myopathic symptoms using oral carnitine supplementation.

Zidovudine can induce a mitochondrial myopathy with ragged-red fibers and partial cytochrome c oxidase deficiency. In an attempt to improve histological assessment of zidovudine myopathy, we evaluated cytochrome c oxidase histochemical reaction in the muscle of 10 patients with biopsy-proven zidovudine myopathy (Group 1), 10 myopathic zidovudine receivers without typical histopathological features of zidovudine myopathy (Group 2), and 10 human immunodeficiency virus (HIV)-infected patients not treated by zidovudine who had an immunohistological profile of HIV-associated myopathy or other neuromuscular disorders (Group 3). Among zidovudine receivers, cytochrome c oxidase deficiency was found in 10 of 10 patients from Group 1 and 7 of 10 from Group 2. No cytochrome c oxidase deficiency was observed in patients not treated by zidovudine. When present, cytochrome c oxidase-negative fibers accounted for 2 to 28% of fibers, and there was no difference for the number of cytochrome c oxidase-negative fibers between Group 1 and Group 2. Most patients with cytochrome c oxidase deficiency that could be evaluated clinically after muscle biopsy improved after withdrawal of zidovudine (5 of 7 in Group 1, 5 of 5 in Group 2). Patients who did not improve had an HIV-associated myopathy concurrently with zidovudine myopathy. We conclude that cytochrome c oxidase reaction may be used as a reliable marker of zidovudine mitochondrial toxicity in HIV-infected patients with muscular symptoms.

Fifty consecutive patients infected with human immunodeficiency virus type 1 (HIV-1) were evaluated regarding the prevalence of HIV-related myopathies and the relevance of zidovudine-related mitochondrial myopathy. Disease stage, total lifetime intake of zidovudine, anthropometric and nutritional parameters, muscle strength, and histochemical and immunohistochemical findings in muscle specimens were recorded. The series was divided into two groups, patients with a total lifetime intake of zidovudine under 200 gm and those with a total lifetime intake over 200 gm. A control group included 50 healthy people matched for age and sex. HIV-related myopathy was defined by the presence of at least one of the classic pathological reactions in muscle, while zidovudine-related myopathy was defined by the presence of ragged red fibers in any percentage. Lower values of the nutritional parameters were detected in the HIV cohort, when compared with normal control values. HIV-related myopathy was detected in 13 (26%) of the 50 patients. There were no differences between groups except for the development of mitochondrial myopathy that occurred in 1 of the 26 patients in Group 1 and in 16 of the 24 in Group II. Six patients who had a total intake of more than 200 gm of zidovudine and demonstrated red ragged fibers in their muscle specimens were absolutely asymptomatic. There was a positive correlation between total intake of zidovudine and the percentage of red ragged fibers in muscle biopsy specimens.