PGD2/DP1 axis promotes liver regeneration by secreting Wnt2 in Kupffer cells in mice.

Abstract

The liver possesses a remarkable regenerative capacity in response to injuries or viral infections. Various growth factors and cytokines are involved in regulating liver regeneration. Prostaglandin (PG) D2, a pro-resolution lipid mediator, is the most abundant hepatic prostanoid. However, the role of PGD2 in the injury-induced liver regeneration remains unclear. Two-thirds partial hepatectomy (70% PH), massive hepatectomy (85% resection), and carbon tetrachloride-induced chronic injury were performed in mice to study the mechanisms of live regeneration. Hepatic PGD2 production was elevated in mice after PH. Global deletion of D prostanoid receptor (DP) 1, but not DP2, slowed PH-induced liver regeneration in mice, as evidenced by lower liver weight to body weight ratio, less Ki67+ hepatocyte proliferation, and G2/M phase hepatocytes. Additionally, DP1 deficiency specifically in resident Kupffer cells (KCs), and not in endothelial cells or hepatic stellate cells, retarded liver regeneration in mice post-PH. Conversely, the overexpression of exogenous DP1 in KCs accelerated liver regeneration in mice. Mechanistically, DP1 activation promoted Wnt2 transcription in a PKA/CREB-dependent manner in resident KCs and mediated hepatocyte proliferation through Frizzled8/β-catenin signaling. Adeno-associated virus vector serotype 8 (AAV8)-mediated Frizzled8 knockdown in hepatocytes attenuated accelerated liver regeneration in KC-DP1 transgenic mice post-PH. Treatment with the DP1 receptor agonist BW245C promotes PH-induced liver regeneration in mice. DP1 activation mediates crosstalk between KCs and hepatocytes through Wnt2, and facilitates liver regeneration. Hence, DP1 may serve as a novel therapeutic target in acute and chronic liver diseases.