Abstract: TH-PO283

LPS-Binding Protein (LBP)/TLR4 Signaling Mediates Pericyte (PC) to Myofibroblasts Trans-Differentiation (PMT) in Endotoxemic AKI

Session Information

Category: Acute Kidney Injury

  • 001 AKI: Basic

Authors

  • Castellano, Giuseppe, University of Bari, Bari, Italy
  • Stasi, Alessandra, University of Bari, Bari, Italy
  • Franzin, Rossana, University of Bari, Bari, Italy
  • Sallustio, Fabio, University of Bari, Bari, Italy
  • Divella, Chiara, University of Bari, Bari, Italy
  • Spinelli, Alessandra, University of Bari, Bari, Italy
  • Grandaliano, Giuseppe, University of Foggia, FOGGIA, Italy
  • Pertosa, Giovanni B., University of Bari, Bari, Italy
  • Gesualdo, Loreto, University of Bari, Bari, Italy
Background

During sepsis, LBP/TLR4 signaling is central in the inflammatory cascade and its activation impairs renal function, leading to AKI. Renal fibrosis induced by PMT is a common pathological feature of chronic kidney disease but little is known in AKI.

Methods

AKI was induced by i.v. LPS infusion in 8 pigs (LPS). After 3h from LPS infusion, 8 pigs were treated with coupled plasma filtration adsorption (CPFA). Renal biopsies, performed at 9h from LPS infusion (T9), were analyzed by IHC and IF. Serum LBP and TGFβ were quantified by ELISA. In vitro, PC (PDGFRβ+) were analyzed by FACS, IF and WB. TGFβ-Receptor(R) neutralizing antibody was added to the cultures 30' before LPS or TGFβ stimulation.

Results

We found the occurrence of acute PMT in endotoxemic AKI by the reduction of PDGFRβ expression and αSMA increase in peritubular PC. CPFA treatment restored PDGFRβ expression (p=0.03) and significantly decreased αSMA+PC (p=0.001), in accordance with reduced serum levels of LBP (p<0.05). In vitro, activation of PC with LPS or endotoxemic sera led to PMT with CollagenI synthesis and αSMA reorganization in contractile fibers (p<0.05). The removal of LBP from septic plasma maintained CollagenI and αSMA expression at basal level (p<0.05). On the contrary, exogenous LBP supplementation reversed CPFA effects. LPS increased phosphorylation of Smad2/3 and ERK1, respectively (p<0.05) suggesting that PMT was induced by both canonical TGFβ-Smad2/3 dependent and non-canonical TGFβ-Smad independent signaling (MAPK). Moreover, the serum levels of TGFβ increased in endotoxemic pigs and were reduced after CPFA treatment (p<0.05). It is well known that TGFβ induces PMT contributing to renal fibrosis. Interestingly, in vitro TGFβR-signaling blockade, did not affect LPS-induced PMT and phosphorylation of SMAD2/3 and ERK1, underlying a fibrotic role of LPS independently of TGFβ synthesis and release.

Conclusion

PC might be pivotal in the generation of myofibroblasts by PMT during AKI upon the activation of LBP/TLR4 signaling. Disrupting the persistent TLR4 signaling activation by the removal of LBP may represent a therapeutic option to prevent PC dysfunction and acute renal fibrosis.