Aging-Related Mitochondrial Dysfunction Is Associated With Fibrosis in Benign Prostatic Hyperplasia

BACKGROUND

Age is the greatest risk factor for lower urinary tract symptoms attributed to benign prostatic hyperplasia (LUTS/BPH). Although LUTS/BPH can be managed with pharmacotherapy, treatment failure has been putatively attributed to numerous pathological features of BPH (eg, prostatic fibrosis, inflammation). Mitochondrial dysfunction is a hallmark of aging; however, its impact on the pathological features of BPH remains unknown.

METHODS

Publicly available gene array data were analyzed. Immunohistochemistry examined mitochondrial proteins in the human prostate. The effect of complex I inhibition (rotenone) on a prostatic cell line was examined using quantitative polymerase chain reaction, immunocytochemistry, and Seahorse assays. Oleic acid (OA) was tested as a bypass of complex I inhibition. Aged mice were treated with OA to examine its effects on urinary dysfunction. Voiding was assessed longitudinally, and a critical complex I protein measured.

RESULTS

Mitochondrial function and fibrosis genes were altered in BPH. Essential mitochondrial proteins (ie, voltage-dependent anion channels 1 and 2, PTEN-induced kinase 1, and NADH dehydrogenase [ubiquinone] iron-sulfur protein 3, mitochondrial [NDUFS3]) were significantly (p < .05) decreased in BPH. Complex I inhibition in cultured cells resulted in decreased respiration, altered NDUFS3 expression, increased collagen deposition, and gene expression. OA ameliorated these effects. OA-treated aged mice had significantly (p < .05) improved voiding function and higher prostatic NDUFS3 expression.

CONCLUSIONS

Complex I dysfunction is a potential contributor to fibrosis and lower urinary tract dysfunction in aged mice. OA partially bypasses complex I inhibition and therefore should be further investigated as a mitochondrial modulator for treatment of LUTS/BPH. Hypotheses generated in this investigation offer a heretofore unexplored cellular target of interest for the management of LUTS/BPH.

Oxidative Stress and Mitochondrial Abnormalities Contribute to Decreased Endothelial Nitric Oxide Synthase Expression and Renal Disease Progression in Early Experimental Polycystic Kidney Disease

Vascular abnormalities are the most important non-cystic complications in Polycystic Kidney Disease (PKD) and contribute to renal disease progression. Endothelial dysfunction and oxidative stress are evident in patients with ADPKD, preserved renal function, and controlled hypertension. The underlying biological mechanisms remain unknown. We hypothesized that in early ADPKD, the reactive oxygen species (ROS)-producing nicotinamide adenine dinucleotide phosphate hydrogen (NAD(P)H)-oxidase complex-4 (NOX4), a major source of ROS in renal tubular epithelial cells (TECs) and endothelial cells (ECs), induces EC mitochondrial abnormalities, contributing to endothelial dysfunction, vascular abnormalities, and renal disease progression. Renal oxidative stress, mitochondrial morphology (electron microscopy), and NOX4 expression were assessed in 4- and 12-week-old PCK and Sprague-Dawley (wild-type, WT) control rats (n = 8 males and 8 females each). Endothelial function was assessed by renal expression of endothelial nitric oxide synthase (eNOS). Peritubular capillaries were counted in hematoxylin-eosin (H&E)-stained slides and correlated with the cystic index. The enlarged cystic kidneys of PCK rats exhibited significant accumulation of 8-hydroxyguanosine (8-OHdG) as early as 4 weeks of age, which became more pronounced at 12 weeks. Mitochondria of TECs lining cysts and ECs exhibited loss of cristae but remained preserved in non-cystic TECs. Renal expression of NOX4 was upregulated in TECs and ECs of PCK rats at 4 weeks of age and further increased at 12 weeks. Contrarily, eNOS immunoreactivity was lower in PCK vs. WT rats at 4 weeks and further decreased at 12 weeks. The peritubular capillary index was lower in PCK vs. WT rats at 12 weeks and correlated inversely with the cystic index. Early PKD is associated with NOX4-induced oxidative stress and mitochondrial abnormalities predominantly in ECs and TECs lining cysts. Endothelial dysfunction precedes capillary loss, and the latter correlates with worsening of renal disease. These observations position NOX4 and EC mitochondria as potential therapeutic targets in PKD.