Aldosterone Induces Renal Fibrosis and Inflammatory M1-Macrophage Subtype via Mineralocorticoid Receptor in Rats

Abstract

We aimed to evaluate macrophages heterogeneity and structural, functional and inflammatory alterations in rat kidney by aldosterone + salt administration. The effects of treatment with spironolactone on above parameters were also analyzed. Male Wistar rats received aldosterone (1 mgkg-1d-1) + 1% NaCl for 3 weeks. Half of the animals were treated with spironolactone (200 mg kg-1d-1). Systolic and diastolic blood pressures were elevated (p<0.05) in aldosterone + salt–treated rats. Relative kidney weight, collagen content, fibronectin, macrophage infiltrate, CTGF, Col I, MMP2, TNF-α, CD68, Arg2, and SGK-1 were increased (p<0.05) in aldosterone + salt–treated rats, being reduced by spironolactone (p<0.05). Increased iNOS and IFN-γ mRNA gene expression (M1 macrophage markers) was observed in aldosterone + salt rats, whereas no significant differences were observed in IL-10 and gene ArgI mRNA expression or ED2 protein content (M2 macrophage markers). All the observed changes were blocked with spironolactone treatment. Macrophage depletion with liposomal clodronate reduced macrophage influx and inflammatory M1 markers (INF-γ or iNOS), whereas interstitial fibrosis was only partially reduced after this intervention, in aldosterone plus salt-treated rats. In conclusion, aldosterone + salt administration mediates inflammatory M1 macrophage phenotype and increased fibrosis throughout mineralocorticoid receptors activation.

The Spleen Promotes the Secretion of CCL2 and Supports an M1 Dominant Phenotype in Hepatic Macrophages During Liver Fibrosis

“…Hepatic non-parenchymal cells were isolated and analyzed by flow cytometry for CD68, CD86, and CD163 expression. We combined these markers to define hepatic macrophage phenotypes as being classically (M1-like, CD68 [10,34]. We found that the proportion of M1-like hepatic macrophages significantly increased whereas the proportion of M2-like macrophages significantly decreased in fibrotic livers compared with healthy controls (Fig.…”

Aldosterone Upregulates Transient Receptor Potential Melastatin 7 (TRPM7)

“…To evaluate statistical significance for normalized protein quantification between three groups, Kruskal-Wallis with Dunn's post-hoc tests were used. In accordance with prior studies studying aldosterone ( 21 , 84 – 88 ) and SGK1 ( 89 ), whole-cell lysates data were normalized to α-tubulin. Furthermore, in this study, α-tubulin levels were unaffected by aldosterone treatment, as relative to control, α-tubulin quantification was 0.88 for aldosterone and 0.89 for aldosterone + GSK-650394 in iWT-TRPM7 cells.…”

Spironolactone mitigates, but does not reverse, the progression of renal fibrosis in a transgenic hypertensive rat

“…There was an intense inflammatory response in the kidneys as evidenced by increased macrophage infiltration in the interstitium, as well as activation of myofibroblasts and profibrotic cytokines such as CTGF and its downstream modulator SMAD2. Aldosterone may contribute to the renal inflammation and injury via modulation of cytokine expression, which promotes inflammatory cell infiltration and albuminuria in hypertension‐driven renal injury (Blasi et al., 2003; Martín‐fernández et al., 2016). In addition, this may be due to upregulation of mineralocorticoid receptor expression in various vascular beds including the renal microcirculation (Delano & Schmid‐Schönbein, 2004), as well as modulating macrophage function (Rickard et al., 2009; Usher et al., 2010).…”

“…The dose of spironolactone applied in experimental research in rodent models is often well in excess of that used clinically, generally equating using an allometric conversion, to a relative human dose of 550 mg/day or more for an average 70‐kg person (Barrera‐Chimal et al., 2012; Han et al., 2006; Klanke et al., 2008; Taira et al., 2008). Additionally, doses are typically administered at the onset, or prior to onset, of hypertension or kidney insult (Barrera‐Chimal et al., 2012; Fujisawa et al., 2004; Martín‐fernández et al., 2016) and not orally administered. Furthermore, dosing is often for a relatively short time period (less than 2 weeks) (Barrera‐Chimal et al., 2012; Klanke et al., 2008; Ortiz et al., 2007) whereas in humans dosage may be continued for years.…”