The protective effects of a novel AT 2 receptor agonist, β-Pro 7 Ang III in ischemia-reperfusion kidney injury.

BACKGROUND AND PURPOSE: This study investigated the reno-protective effects of a highly selective AT2 R agonist peptide, β-Pro7 Ang III in a mouse model of acute kidney injury (AKI).

METHODS: C57BL/6 J mice underwent either sham surgery or unilateral kidney ischemia-reperfusion injury (IRI) for 40 min. IRI mice were treated with either β-Pro7 Ang III or perindopril and at 7 days post-surgery the kidneys analysed for histopathology and the development of fibrosis and matrix metalloproteinase (MMP)-2 and -9 activity. The association of the therapeutic effects of β-Pro7 Ang III with macrophage number and phenotype was determined in vivo and in vitro.

KEY RESULTS: Decreased kidney tubular injury, interstitial matrix expansion and reduced interstitial immune cell infiltration in IRI mice receiving β-Pro7 Ang III treatment was observed at day 7, compared to IRI mice without treatment. This correlated to reduced collagen accumulation and MMP-2 activity in IRI mice following β-Pro7 Ang III treatment. FACS analysis showed a reduced number and proportion of CD45+ CD11b+ F4/80+ macrophages in IRI kidneys in response to β-Pro7 Ang III, correlating with a significant increase in M2 macrophage markers and decreased M1 markers at day 3 and 7 post-IR injury, respectively. In vitro analysis of cultured THP-1 cells showed that β-Pro7 Ang III attenuated lipopolysaccharide (LPS)-induced tumour necrosis factor-α (TNF-α) and interleukin (IL)- 6 production but increased IL-10 secretion, compared to LPS alone.

CONCLUSION: Administration of β-Pro7 Ang III via mini-pump improved kidney structure and reduced interstitial collagen accumulation, in parallel with an alteration of macrophage phenotype and anti-inflammatory cytokine release, therefore mitigating the downstream progression of ischemic AKI.