Recombinant high-density lipoprotein modulates inflammatory response and renal dysfunction in a swinemodel of sepsis-induced acute kidney injury

Abstract Background and Aims Sepsis is a severe and dysregulated inflammatory disease that often precedes the development of acute kidney injury (AKI) with consequent worsening outcome. Although clinical data demonstrate that high-density lipoprotein (HDL) levels drop in septic patients with a poor prognosis, little is known about the molecular basis of HDL's role in systemic inflammation and renal function. Here we investigate the possible effects of a novel engineered HDL-mimetic (CER-001) in a swine model of lipopolysaccharide (LPS)-induced AKI. Method Sepsis was induced by intravenous infusion of a saline solution containing 300 μg/kg of LPS in a porcine model. The animals were randomized into three groups: LPS (endotoxemic pigs, n = 6), CER20 (endotoxemic pigs treated with a single dose of CER-001 20mg/kg; n = 6), and CER20 × 2 (endotoxemic pigs treated with two doses of CER001 20mg/kg; n = 6). Animals were sacrificed after 24h from the start of experimental procedure. Renal histologic and biochemical changes were analyzed. Endothelial dysfunction biomarkers, circulating pro-inflammatory mediators, LPS and Apolipoprotein A-I (Apo A-I) levels were quantified with ELISA assay. Systemic complement activation was evaluated by Wieslab kit. Results Untreated animals were highly susceptible to LPS challenge and usually succumbed before completing the study protocol (LPS group 16.7%). CER-001 treatment increased the survival rate of endotoxemic pigs, compared to the LPS group (CER20, 50%; CER20 × 2, 66.7%). Furthermore, as shown in Figure 1A, LPS injection led to a time-dependent increase of IL-6 in endotoxemic animals respect to basal condition (T0). CER-001 treatment was able to reverse LPS effects. In particular, the second infusion of CER-001 three hours after the first dose (T3) strongly reduced IL-6 serum levels back to basal level (LPS p <0.05). Similarly, we found high levels of TNF-α and MCP-1 in endotoxemic pigs that were significantly decreased in both CER-001 treatment arms (T24, CER20 × 2 vs LPS group, IL-6, p = 0.0086; TNF-α, p<0.0001; MCP-1, p = 0.0009). In addition, CER-001 treatment ameliorated systemic endothelial dysfunction by reducing VCAM and ICAM serum levels. A significant activation of classical and alternative complement pathway (vs T0 p <0.05) was observed at 1h, 3h and 24h after LPS infusion. CER001 treatment significantly prevented systemic complement activation in both treated groups (vs LPS p <0.05). We also investigated whether CER001 infusions significantly prevented renal tissue damage. Endotoxemic pigs presented oliguric AKI with increased tubulo-interstitial infiltrate, extensive collagen deposition, and glomerular thrombi; CER-001 treatment preserved renal parenchyma, recovered urine output, decreased creatine levels, and reduced the biomarkers of tubular damage, Cystatin C and KIM-1, both in serum and urine samples. Considering that HDL has a very high affinity for LPS, we evaluated the circulating LPS concentration in treated animals. We observed that LPS levels were greatly reduced in treated animals and the effects are more evident after the second infusion of CER-001(Figure 1B). Therefore, we also examined LPS levels in bile samples and we observed a dose-dependent increasing amount of endotoxin in the CER001 treated septic pigs. Conclusion This preclinical data indicates that CER001 treatment prevents systemic inflammation thereby limiting renal damage. The mechanism of action is two-fold consisting of both the scavenging of endotoxin and a direct anti-inflammatory effect of CER-001.