INFLAMMATION, TISSUE DAMAGE AND METABOLIC DEREGULATION IN A MOUSE MODEL OF MILD SEPSIS-RELATED ACUTE KIDNEY INJURY: TOWARDS THE DEVELOPMENT OF NEW DIAGNOSTIC AND THERAPEUTIC STRATEGIES

Acute kidney injury (AKI) is defined as a sudden loss of kidney function and affects many patients hospitalized in intensive care units. It is characterized by cellular damage and inflammation that impair kidney function and eventually evolve in fibrosis and chronic kidney disease (CKD). In particular, sepsis, i.e. a dysregulated response to infection which leads to multi-organ dysfunction, is the most common cause of AKI (S-AKI). The lack of effective diagnostic markers and adequate therapeutic solutions for AKI makes it urgent to advance knowledge and develop new clinical strategies. In this context, we aim to develop a pre-clinical model to better characterize the initial stages of mild S-AKI and its potential progression to chronic kidney disease, in order to test new strategies to prevent kidney damage. 

Female and male mice were subjected to moderate CLP. Kidney function was assessed using serum creatinine and BUN. Proximal tubule damage was determined by immunofluorescence detection of KIM-1. Pro-inflammatory cytokines were quantified by qPCR. Vacuolization (H&E) and lipid droplets (red oil labeling) were observed by confocal microscopy.

At 24- and 72-hours post-CLP, we detected tissue damage in male and female CLP mice, with vacuolization and dilation of the renal tubules. Although infiltration of immune cells such as neutrophils appeared moderate by Immunofluorescence (IF) analysis, we measured an increased expression of inflammatory markers by qPCR (Cxcl1, Ccl2, Il6, Tnf, Il1β), indicating an inflammatory status at 24h post-op. Increased expression of KIM-1 and a significant accumulation of lipid droplets were observed in proximal tubules at 24 hours post-CLP, indicating cellular damage and metabolic deregulation. However, traditional markers of AKI (sCr, BUN) did not show sufficient sensitivity to detect kidney distress following sepsis generated by a mild CLP procedure, highlighting the need to validate new, more effective markers. 

These preliminary results support the validity of our experimental model for S-AKI and highlight the inflammatory status and the metabolic deregulation occurring in renal epithelial cells even under mild sepsis. Further analysis is currently evolving towards a deeper characterization of the immune landscape and the lipid metabolism dysregulation, as well as the transcriptomic response of renal epithelial cells. Next, we will evaluate the involvement of the pro-inflammatory receptor P2Y14 in the development of renal inflammation in S-AKI. We previously showed using a pre-clinical model of bilateral renal ischemia AKI that activation of P2Y14 triggers renal inflammation and worsens ischemia-induced renal tubule damage. P2Y14, located on the apical surface of collecting duct epithelial cells, is activated by UDP-sugars which are released by damaged proximal tubules. Thus, the UDP-sugar/P2Y14 pathway appears as a promising target for a new diagnostic marker and a therapeutic target for AKI of different etiology. The overall objective of our research is to provide an in-depth understanding of the contribution of the pro-inflammatory P2Y14 receptor in S-AKI.