LPA/PKD-1-FoxO1-CD36 Signaling Axis Regulates Capillary Arterialization in Ischemic Conditions

Endothelial cells (ECs) are critical in effective arterial remodeling to supply blood in ischemic conditions. We recently showed that lysophosphatidic acid (LPA)/protein kinase (PKD-1) signaling suppresses CD36 transcription in microvascular ECs (MVECs), leading to transcriptional reprogramming towards arteriogenic gene expression. This process is regulated by PKD-1 mediated interaction between histone deacetylase HDAC7 and transcription factor FoxO1 in the nuclei. Moreover, our in vivo studies implicate that LPA/PKD-1-mediated CD36 transcriptional repression is involved in microvascular remodeling. We thus hypothesize that LPA/PKD-1-FoxO1-CD36 signaling axis regulates capillary arterialization in ischemic settings. To test this hypothesis, we transduced MVECs with lentiviral FoxO1 and found an increase in CD36 mRNA levels, along with change of arteriogenic gene expression. This was attenuated by co-transduction of FCoR, or LPA treatment (p in vivo , we established a hindlimb ischemia model in EC-specific pkd-1 null mice. The functional outcomes, assessed by the Tarlov ischemia scale, were significantly worse in the null mice compared to the controls. The Tarlov scores were 2±0.71, 2.2±1.3, 2.6±1.67, 3±2, 3.75±2.87, and 3.33±3.06 vs 3±0.47, 4.1± 0.7, 5.6±0.5, 5.8±0.4, 6, and 6, at day 1, 3, 5, 7, 14 and 21 post surgery. Laser Doppler Perfusion Imaging showed worse blood supply in the ischemic limb in the null mice. L/R ratios prior to, and post surgery at day 0, 3, 7, 14 were 1.11±0.12, 0.11±0.06, 0.20±0.07, 0.22±0.09 vs 0.25±0.13 in the null mice vs 1.01±0.11, 0.12±0.05, 0.29±.09, 0.47±0.14, and 0.56±0.33 in the control, consistent with a defect in microvascular arterialization. Intriguingly, Masson’s Trichrome assays showed strong collagen staining and extensive bleeding in the muscle of the null mice at day 7, indicating severe tissue fibrosis and vascular leakage after ischemic insults. In conclusion, our studies indicate that LPA/PKD-1-FoxO1-CD36 signaling axis may be important in capillary arterialization in the ischemic conditions.