The protective effects of a novel AT2 receptor agonist, β-Pro7 Ang III
in ischemia-reperfusion kidney injury
Abstract
Background and Purpose: This study investigated the reno-protective
effects of a highly selective AT2R agonist peptide, β-Pro7Ang III in a
mouse model of acute kidney injury (AKI). Experimental Approach:
C57BL/6J mice underwent either sham surgery or unilateral kidney
ischemia-reperfusion injury (IRI) for 40 minutes. IRI mice were treated
with either β-Pro7Ang 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-Pro7Ang 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-Pro7Ang
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-Pro7Ang III treatment. FACS analysis
showed a reduced number and proportion of CD45+CD11b+F4/80+ macrophages
in IRI kidneys in response to β-Pro7Ang 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-Pro7Ang 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 and Implications: Therapeutic delivery of
β-Pro7Ang III was renoprotective via alteration of macrophage phenotype
and anti-inflammatory cytokine release, therefore mitigating the
downstream progression of ischemic AKI.