The Pro-vs. Anti-Angiogenic Capacity of Short Chain Fatty Acids is Dependent on the Bioavailability of FFAR3 in...

Our current study builds on our recent report that showed Palmitate aggravates ischemic endothelial (EC) dysfunction in vitro and aims to determine whether Palmitate is a critical determinant of PAD severity. In contrast to Palmitate, we studied the role of short-chain fatty acids (SCFAs) in regulating ischemic revascularization in PAD.

Femoral artery ligation and resection was used as preclinical-PAD model. Hypoxia serum starvation was used as in vitro PAD model.

Palmitate dramatically decreased ischemic-EC survival and angiogenic capacity in vitro , whereas SCFAs significantly induced their angiogenic capacity. LC-MRM MS analysis showed decreased SCFA content in ischemic-muscle. Laser Speckle perfusion imaging showed that intramuscular SCFA treatment significantly induced perfusion recovery, whereas Palmitate showed a modest but significant impairment in perfusion recovery. Immunoblot analysis showed that SCFAs preferentially induce Free fatty acid receptor (FFAR)-3, but not FFAR2. Accordingly, silencing FFAR3 decreased ischemic-EC angiogenic capacity, whereas inhibiting FFAR2 induced ischemic angiogenesis. Pharmacological inhibition of FFAR3 by beta-hydroxybutyrate (BHB) significantly decreased perfusion recovery. SCFA treatment further decreased perfusion recovery in BHB-treated ischemic-muscle. Mechanistically, inhibiting FFAR3-induced FFAR2-levels that inhibited ischemic-EC angiogenic capacity by decreasing NO and inducing ROS levels in SCFA-treated ischemic-ECs.

Our data shows that Palmitate alone is not sufficient to drive the PAD severity. Increased FFAR3 levels in ischemic-muscle allow SCFAs to activate the AKT-NO axis to induce ischemic angiogenesis and perfusion recovery. However, loss of FFAR3 in ischemic-muscle promotes FFAR2 activation that blocks SCFA-induced NO-production and redox balance thereby inhibiting perfusion recovery in preclinical-PAD.