Involvement of aquaporin 5 and Na-K-2Cl co-transporter 1 in the pathogenesis of primary focal hyperhidrosis: evidence from the primary sweat gland cell culture.

People with primary focal hyperhidrosis (PFH) usually have an overactive sympathetic nervous system, which can activate the sweat glands through the chemical messenger of acetylcholine. The role of aquaporin 5 (AQP5) and Na-K-2Cl co-transporter 1 (NKCC1) in PFH is still unknown. The relative mRNA and protein levels of AQP5 and NKCC1 in the sweat gland tissues of three subtypes of PFH patients (primary palmar hyperhidrosis, PPH; primary axillary hyperhidrosis, PAH; primary craniofacial hyperhidrosis, PCH) were detected with Real-Time PCR (qPCR) and Western blot. Primary sweat gland cells from healthy controls (NPFH-SG) were incubated with different concentrations of acetylcholine, and the relative mRNA and protein expression of AQP5 and NKCC1 were also detected. NPFH-SG cells were also transfected with si-AQP5 or shNKCC1, and acetylcholine stimulation-induced calcium transients were assayed with Fluo-3 AM calcium assay. Up-regulated AQP5 and NKCC1 expression were observed in sweat gland tissues, and AQP5 demonstrated a positive Pearson correlation with NKCC1 in PPH patients ( r =0.66, p <0.001), PAH patients ( r =0.71, p <0.001), and PCH patients ( r =0.62, p <0.001). Up-regulated AQP5 and NKCC1 expression were also detected in primary sweat gland cells derived from three subtypes of PFH patients when compared with primary sweat gland cells derived from healthy control. Acetylcholine stimulation could induce the up-regulated AQP5 and NKCC1 expression in NPFH-SG cells, and AQP5 or NKCC1 inhibitions attenuated the calcium transients induced by acetylcholine stimulation in NPFH-SG cells. The dependence of ACh-stimulated calcium transients on AQP5 and NKCC1 expression may be involved in the development of PFH.