Proinflammatory/profibrotic effects of aldosterone in Gitelman's syndrome, a human model opposite to hypertension

Aldosterone proinflammatory/profibrotic effects are mediated by the induction of mononuclear leucocytes (MNL) to express oxidative stress (OxSt)-related proteins, such as p22^phox, and by the activation of RhoA/Rho kinase pathway. Gitelman's syndrome (GS), an autosomal recessive tubulopathy, is an interesting opposite model to hypertension, being characterized by hypokalemia, activation of renin-angiotensin-aldosterone system yet normo/hypotension and lack of cardiovascular-renal remodeling. We aimed to evaluate the proinflammatory/profibrotic effect of aldosterone in MNL of 6 GS patients compared with 6 healthy subjects (HS).

p22^phox expression and MYPT-1 phosphorylation status, a marker of RhoA/Rho kinase pathway activation, were evaluated in MNL of GS patients and HS at baseline and after incubation with aldosterone (1 × 10^-8 M) alone or with canrenone (1 × 10^-6 M).

At basal condition, p22^phox expression was significantly higher in HS than in GS patients (1.02 ± 0.05 densitometric unit (du) vs 0.40 ± 0.1 du, respectively). Aldosterone significantly increased p22^phox expression in HS and this effect was reversed by coincubation with canrenone (1.4 ± 0.05 du and 1.09 ± 0.03 du, respectively). No significant change was reported in GS after incubation of MNL with aldosterone and/or canrenone compared with basaline. Even MYPT-1 phosphorylation was significantly higher in HS compared with GS patients at basal condition (1.16 ± 0.1 du vs 0.69 ± 0.07, respectively). Aldosterone significantly increased MYPT-1 phosphorylation only in HS (1.37 ± 0.1 du vs 0.83 ± 0.12 du in GS).

GS patients seem to be protected by the OxSt status induced by aldosterone and revealed in HS. This human model could provide additional clues to highlight the proinflammatory/cardiovascular remodeling effects of aldosterone.