PTX3 has been recently implicated in the promotion of vascular inflammation via the activation of Complement.
Aim of this work was to investigate the possible involvement of PTX3 in renal I/R injury.
PBMCs were isolated from blood of patients with Delay graft function (DGF, n=10) and Early graft function (EGF, n=10) at T0 and T24h from transplant. Gene expression profiles of PBMCs from both groups were assessed by Affymetrix technologies.
Results were evaluated by statistical analysis and functional pathway analysis and validated by confocal analysis on a swine model of I/R injury. Renal I was induced in 5 pigs by arterial clamping for 30 min and tissues were analyzed at different time points after R (T15’, 30’, 60’).
Microarray analysis (Venn diagram, FDR<5% and a FC>1,5) revealed that the expression of genes PTX3 and C3 is downregulated in EGF compared to DGF patients (Figura1 and Figura2) . On the contrary, the gene CR1 is upregulated in DGF (Figura3).
Furthermore, in the pig model, confocal laser microscopy demonstrated PTX3 deposits already at 15’ of R, localized at peritubular (T15 7.7±1.1; p=0.005) and glomerular (8.2±2.5; p=0.03) capillary levels (Figura4). We found a significant increase in infiltrating interstitial leucocytes such as CD163+/PTX3+ monocyte-macrophages (6.2±2.1; p=0.05) and SWC3a+/PTX3+ dendritic cells (3.7±0.5 p=0.05) compared to T0 . Finally, we identified tubulo-interstitial FSP1+/PTX3+ myofibroblast(4.1±1.3; p=0.04) (Figura5). Co-localization between C5b-9 and PTX3 on renal endothelial cells clearly demonstrated the activation of Complement system in presence of PTX3 deposits.(Figura6)
Our data would suggest a key role of PTX3 synthetized by peripheral blood mononuclear cells (PBMCs) during DGF that induced an early activation of complement in transplant kidney.