Morphological evaluation of sympathetic renal innervation in patients with autosomal dominant polycystic kidney disease

Several evidences support the hypothesis that patients affected by autosomal dominant polycystic kidney disease (ASPKD) show a sympathetic renal hyperactivity. Nevertheless, no morphological evidences are available yet. Therefore, the aim of the study was to demonstrate that an increase in sympathetic renal artery innervation was present in the ADPKD patients by using histological methods. In addition, here we correlated the sympathetic renal artery innervation with the evolutionary state of ADPKD (increase in volume of kidney, onset of chronic renal failure and hypertension). To this end, peri-adventitial innervation of renal arteries was studied using morphological methods from 49 patients in total: 29 underwent surgical nephrectomies for ADPKD and 20 non-dialysis patients (CTRL group) undergoing nephrectomy for other diseases. Nerve density (number of nerves per mm2) was evaluated in the peri-adventitial tissue in a concentric ring that was located within 2 mm from the beginning of the adventitia by using immunohistochemistry. The total nerve density was significantly increased in the ADPKD group (1.26 ± 0.82 × mm2) as compared to controls (0.78 ± 0.40 × mm2) (p = 0.02). Hypertensive patients with ADPKD showed a greater nerve density than control hypertensives. However, the increase in renal sympathetic innervation in the ADPKD patients was found to be independent of hypertension, resistance to antihypertensive therapy, age, sex and kidney volume, as demonstrated by the uni and multivariate analysis. In conclusion, our study better clarifies the effect of sympathetic hyperactivity in the progression of polycystic disease.