Background:  Evidence is mounting that metabolic complications of HAART result from mitochondrial dysfunction. Nucleoside reverse transcriptase inhibitors (NRTI) inhibit mitochondrial DNA pol-g and mtDNA depletion has been observed in subcutaneous fat of HIV⁺ lipoatrophy patients. However, studies on mtDNA levels in tissues used for routine sampling, such as peripheral blood mononuclear cells (PBMC), are equivocal and controversial. Consequently there has been a call for simple tests of mitochondrial function more suitable for the study and diagnosis of metabolic complications. We have developed simple dipstick tests to measure levels of key enzymes of the mitochondrial oxidative phosphorylation (OXPHOS) system, which is responsible for >95% of ATP production in normally functioning cells. We show here that the tests have clinical utility to monitor adverse effects of HAART in both fat and PBMCs.

Methods:  Quantitative 2-site immunoassay dipstick tests were used to measure levels of OXPHOS enzyme complexes I (CI:  NADH dehydrogenase) and IV (CIV:  cytochrome c oxidase) in gluteal subcutaneous adipose tissue and PBMC of 26 patients forming 3 cohorts:  HIV^­, HIV⁺ lipoatrophy^­, and HIV⁺ lipoatrophy⁺ (cohorts 2 and 3 on HAART). Lipoatrophy was determined by patient report and physician concurrence. MtDNA copies/cell were assayed by RTPCR using primers for the mtDNA NADH dehydrogenase 2 and the nuclear Fas gene.

Results:   Both CI and CIV were reduced significantly in fat and PBMC of the HIV⁺ lipoatrophy⁺ cohort compared to the HIV^­ cohort. Intermediate levels of both enzymes were also seen in fat and PBMC of the HIV⁺ lipoatrophy^­ cohort, but these differences were not statistically significant, possibly due to low sample number of the HIV⁺ lipoatrophy^­ cohort. MtDNA levels in fat were reduced significantly in the HIV⁺ lipoatrophy^­ and HIV⁺ lipoatrophy⁺ cohorts.

Conclusions:  The results show that these simple dipstick assays for mitochondrial enzymes have clinical utility to monitor adverse effects of HAART, i.e., they reveal mitochondrial dysfunction in lipoatrophy⁺ patients. As the tests work on easily accessed tissue samples, they will facilitate study of HAART-associated mitochondrial dysfunction and may be useful aids to guide therapy. Moreover, because they are simple, robust, and inexpensive, the tests hold promise for use in resource-poor settings.