CD40 also plays a crucial role in the innate response and its inhibition is related to a decrease of mortality in experimental septic models [38]. Moreover, the activation of the CD40/CD154 pathway Enzastaurin Phase 3 in TEC induces a pro-fibrotic and pro-inflammatory state [39,40]. We found that after Amberchrom resin adsorption, septic plasma lost the capacity to up-regulate ICAM-1 and to activate the CD40/CD154 pathway on cultured human TEC. This effect may be ascribed to the removal of soluble CD154 from septic plasma. In the course of sepsis, activated platelets and leukocytes may release high amounts of soluble CD154 from their surface that interacts with the CD40 expressed by TEC and other target cells [41,42]. In this setting, the removal of soluble CD154 as well as other inflammatory mediators by resin adsorption may lead to the inhibition of PMN adhesion to TEC.

It has been suggested that apoptosis plays a key role in the pathogenetic mechanisms of sepsis-related tissue injury including AKI [5,7,43-45]. However, a systematic review of the histopathological findings in septic AKI reported a normal histology in the majority of cases [46]. As apoptosis is a reversible process and apoptotic cells are rapidly removed by phagocytic cells it may be difficult to detect tubular apoptotic cells in the histological specimens.Tubular injury is not the mere result of renal hypoperfusion or cortico-medullary redistribution of blood flow [5,47]. A direct toxic effect of circulating or locally-produced inflammatory cytokines and LPS has been postulated as the main cause of sepsis-related AKI [7-10].

We found that TEC apoptosis was induced by incubation with septic plasma through the activation of Fas and caspases. These events were all abrogated following Amberchrom resin adsorption of septic plasma. Indeed, we observed a significant reduction of TNF-��, soluble Fas-L and soluble CD154 in septic plasma after incubation with the Amberchrom resin. The relevance of TNF-��, soluble Fas-L and soluble CD154 in inducing TEC injury was confirmed by the observed decrease of apoptosis in TEC engineered to knock-down Fas, CD40 or TNF-R1 by specific siRNA. These results suggest that the unselective removal of circulating inflammatory substances by Amberchrom resin may be responsible for the inhibited activation of the death receptor-mediated apoptotic pathway in TEC.

With the purpose of evaluating the protective effect of resin adsorption on the extension of sepsis-associated AKI after the initial insult, we performed a set of experiments aimed at evaluating the AV-951 role of a ‘priming activity’ of septic plasma on TEC apoptosis. We found that the pre-incubation of tubular cells with septic plasma provoked an additional effect on apoptosis induced by LPS and inflammatory cytokines. This effect was decreased after adsorption of septic plasma by CG161 M resin. These results suggest that plasma adsorption may limit the continued renal injury sustained by these mediators.