A Soluble Form of P Selectin Glycoprotein Ligand 1 Requires Signaling by Nuclear Factor Erythroid 2–Related Factor 2 to Protect Liver Transplant Endothelial Cells Against Ischemia–Reperfusion Injury

Abstract

Liver endothelial cell (LEC) damage is essential in the pathogenesis of ischemia-reperfusion injury (IRI) in transplant recipients. We analyzed the mechanism of LEC resistance against IRI by using a novel recombinant soluble form of PSGL-1 (Tandem P-Selectin Glycoprotein Ligand-Immunoglobulin; TSGL-Ig) in a mouse model of hepatic cold preservation (4°C in UW for 20h) and syngeneic orthotopic liver transplantation (OLT). Unlike in controls, TSGL-Ig protected OLT against IR-stress, evidenced by depressed sALT levels, well-preserved hepatic architecture, and improved survival (42% vs. 92%). TSGL-Ig suppressed neutrophil/macrophage sequestration and pro-inflammatory cytokine/chemokine programs in OLT. Treatment with TSGL-Ig mitigated LEC activation (P-/E-selectin, VCAM-1/ICAM-1 expression). In parallel in vitro studies, TSGL-Ig diminished cellular damage in H2O2-stressed LEC cultures (LDH/ALT levels). Increased Trx, GCL, NQO1, and HIF-1α expression, along with transcription factor Nrf2, implied TSGL-Ig exerts anti-oxidant functions in IR-stressed OLT and H2O2-stressed LECs. Indeed, Nrf2-deficient livers suffered fulminant IRI, compared with WT despite concomitant TSGL-Ig therapy. Thus, TSGL-Ig is not only acting as competitive antagonist blocking leukocyte migration into IR-stressed liver, but it may also act directly as an agonist stimulating Nrf2-mediated cytoprotection in LECs. This study supports the role of P-selectin signaling in hepatic homeostasis in OLT, with broad implications for tissue damage conditions.

Soluble P-selectin promotes retinal ganglion cell survival through activation of Nrf2 signaling after ischemia injury

“…NRF2 is needed for PSGL-1-mediated protection of the liver following ischemia-reperfusion injury. 27 PSGL-1 is a well-known ligand of P-selectin; therefore, we targeted Nrf2 and other AREs. Nrf2 expression significantly increased in the 4 μ g P-sel-treated group ( Figure 7b ) compared with expression in the PBS-treated group.…”

“… 32 Furthermore, we demonstrated that P-sel-IgG exerts neuroprotection via the Nrf2 signaling pathway, consistent with a previous study that used a similar kind of PSGL-1 recombinant protein. 27 In addition, Nrf2 activation is protective in intracerebral hemorrhage 33 and middle cerebral artery occlusion in the brain, 34 which are also CNS disorders, along with AION. P-selectin is involved in maintaining blood–brain–barrier integrity 35 ; in a similar manner, PSGL-1 inhibition stabilized the BONB in this study.…”

“…The P-selectin–PSGL-1 (P-selectin glycoprotein ligand-1) interaction supports leukocyte rolling and firm adhesion, leading to transmigration in surrounding tissue that triggers an inflammatory response cascade. 24 A soluble recombinant form of exogenous P-selectin can restore hemostasis in a mouse model of hemophilia, 25 rescue viper venom-induced mortality, 26 rescue liver endothelial cells from ischemic reperfusion injury 27 and ameliorate inflammation. 28 All these findings are based on one common principle; the soluble recombinant form of exogenous P-selectin competes with endogenous membrane bound P-selectin molecules to bind with PSGL-1, a well-known ligand for P-selectin.…”

“… 28 All these findings are based on one common principle; the soluble recombinant form of exogenous P-selectin competes with endogenous membrane bound P-selectin molecules to bind with PSGL-1, a well-known ligand for P-selectin. 26 , 27 Considering the similar pathophysiology in rAION, including ischemia, photothrombosis, 1 and inflammation, 29 we investigated the therapeutic potential of soluble P-selectin in ischemic injury. We hypothesize that P-sel-IgG treatment can be neuroprotective for the ON and RGCs, resulting in preserved visual function.…”

Decoding the single-cell landscape and intercellular crosstalk in the transplanted liver: a 4-dimension mouse model

“…The transplanted liver and serum samples were collected at 3H, 6H,12H, 1D, 3D, 7D, and 14D post-LT. Biochemical parameters including ALT and aspartate aminotransferase (AST) were measured with a BioVision system. The severity of liver ischemia-reperfusion injury (IRI) was graded by modified Suzuki’s histological criteria [18].…”