#3252 Anti-fibrotic profile of a next-generation AT2 receptor agonist in human fibrotic kidney tissue

Abstract Background and Aims Chronic kidney disease (CKD) represents a significant global health burden, underscoring the urgent need for novel and more effective therapies. The angiotensin II type 2 receptor (AT2R) is expressed in renal tissues, and its activation has been shown to elicit anti-inflammatory, anti-fibrotic, and vasodilatory effects—properties that could be beneficial in halting CKD progression. Previous studies with AT2R agonists, such as buloxibutid (also referred to as C21), have demonstrated efficacy in preclinical models of CKD by reducing fibrosis, inflammation, and improving renal function. This study aimed to investigate the therapeutic potential of a new highly potent and selective AT2R agonist, referred to as C112, using ex vivo human fibrotic kidney slices to assess its anti-fibrotic and fibrolytic properties. Method Human precision-cut kidney slices (PCKS) were prepared from explanted kidney tissue with early fibrotic changes and incubated for up to 96 hours with either vehicle, the reference AT2R agonist buloxibutid (IC50: 5.7 nM), or escalating concentrations of the novel AT2R agonist C112 (IC50: 0.41 nM). Key profibrotic markers collagen type I alpha-1 (COL1A1) and transforming growth factor-β1 (TGF-β1) levels were quantified using immunoassays. The protein levels of matrix metalloproteinase-1 (MMP-1), a fibrolytic collagenase, were also measured to determine the fibrolytic potential of each treatment. PCKS viability was assessed by immunoassay-based measurement of kidney injury molecule-1 (KIM-1) levels in the culture supernatants. Results Treatment with the buloxibutid and C112 dose-dependently reduced COL1A1 and TGF-β1 levels, with C112 being more potent than buloxibutid. In parallel, both compounds markedly increased MMP-1 levels, potentially reflecting enhanced collagen breakdown. The full effects of buloxibutid and C112 on MMP-1 were seen already at the lowest concentrations tested (0.01 and 0.001 nM, respectively). These findings suggest that C112 exerts a stronger overall anti-fibrotic effect than buloxibutid in this ex vivo model of human renal fibrosis. KIM-1 was relatively stable over the first 48 hours with a subsequent slow increase over the course of the experiment, in keeping with the responses of an aged kidney. No significant increase of KIM-1 was detected in response to any of the treatments used in this study. Conclusion The superior anti-fibrotic profile of the novel highly potent and selective AT2R agonist C112 in human fibrotic kidney slices highlights the potential for AT2R-targeted interventions in CKD. By reducing profibrotic mediators (COL1A1 and TGF-β1) and increasing the fibrolytic protease MMP-1, AT2R agonists may offer a valuable new therapeutic approach for CKD management. Studies of C112 in vivo are ongoing to confirm these promising translational ex vivo findings.