Targeting Uric Acid Prevents Brain Injury and Anxiety in a Rat Model of Hemorrhagic Shock.

ABSTRACT: Secondary brain injury following hemorrhagic shock (HS) is a frequent complication in patients, even in the absence of direct brain trauma, leading to behavioral changes and more specifically anxiety and depression. Despite preclinical studies showing inflammation and apoptosis in the brain after HS, none have addressed the impact of circulating mediators. Our group demonstrated an increased uric acid (UA) circulation in rats following HS. Since UA is implicated in endothelial dysfunction and inflammatory response, we hypothesized UA could alter the blood-brain barrier (BBB) and impact the brain. Male Wistar rats were randomly assigned to: SHAM, HS (hemorrhagic shock) and HS + U (hemorrhagic shock + 1.5 mg/kg of uricase). The uricase intervention, specifically targeting UA, was administered during fluid resuscitation. It prevented BBB dysfunction (fluorescein sodium salt permeability and expression of intercellular adhesion molecule-1) following HS. As for neuroinflammation, all of the results obtained (MPO activity; Iba1 and GFAP expression) showed a significant increase after HS, also prevented by the uricase. The same pattern was observed after quantification of apoptosis (caspase-3 activity and TUNEL) and neurodegeneration (Fluoro-Jade). Finally, the forced swim, elevated plus maze, and social interaction tests detected anxiety-like behavior after HS, which was blunted in rats treated with the uricase. In conclusion, we have identified UA as a new circulatory inflammatory mediator, responsible for brain alterations and anxious behavior after HS in a murine model. The ability to target UA holds the potential of an adjunctive therapeutic solution to reduce brain dysfunction related to hemorrhagic shock in human.

Impact of uric acid on liver injury and intestinal permeability following resuscitated hemorrhagic shock in rats.

BACKGROUND: Multiorgan failure is a consequence of severe ischemia-reperfusion injury after traumatic hemorrhagic shock (HS), a major cause of mortality in trauma patients. Circulating uric acid (UA), released from cell lysis, is known to activate proinflammatory and proapoptotic pathways and has been associated with poor clinical outcomes among critically ill patients. Our group has recently shown a mediator role for UA in kidney and lung injury, but its role in liver and enteric damage after HS remains undefined. Therefore, the objective of this study was to evaluate the role of UA on liver and enteric injury after resuscitated HS. METHODS: A murine model of resuscitated HS was treated during resuscitation with a recombinant uricase, a urate oxidase enzyme (rasburicase; Sanofi-Aventis, Canada Inc, Laval, Canada), to metabolize and reduce circulating UA. Biochemical analyses (liver enzymes, liver apoptotic, and inflammatory markers) were performed at 24 hours and 72 hours after HS. Physiological testing for enteric permeability and gut bacterial product translocation measurement (plasma endotoxin) were performed 72 hours after HS. In vitro, HT-29 cells were exposed to UA, and the expression of intercellular adhesion proteins (ZO-1, E-cadherin) was measured to evaluate the influence of UA on enteric permeability. RESULTS: The addition of uricase to resuscitation significantly reduced circulating and liver UA levels after HS. It also prevented HS-induced hepatolysis and liver apoptotic/inflammatory mediators at 24 hours and 72 hours. Hemorrhagic shock-induced enteric hyperpermeability and endotoxemia were prevented with uricase. CONCLUSIONS: After resuscitated HS, UA is an important mediator in liver and enteric injury. Uric acid represents a therapeutic target to minimize organ damage in polytrauma patients sustaining HS.

Caspase-(8/3) activation and organ inflammation in a rat model of resuscitated hemorrhagic shock: A role for uric acid.

BACKGROUND: Multiple organ failure can develop after hemorrhagic shock (HS). Uric acid (UA) is released from dying cells and can be proinflammatory. We hypothesized that UA could be an alternative mediator of organ apoptosis and inflammation after HS. METHODS: Ventilated male Wistar rats were used for the HS model. Two durations of shock (5 minutes vs. 60 minutes) were compared, and shams were instrumented only; animals were resuscitated and observed for 24 hours/72 hours. Caspases-(8/3), myeloperoxidase (MPO), TNF-α were measured in lungs and kidneys. Plasma UA and cytokine (IL-1ß, IL-18, TNF-α) were measured. A second set of animals were randomized to vehicle versus Rasburicase intraperitoneal intervention (to degrade UA) during resuscitation. Another group received exogenous UA intraperitoneally without HS. Measures mentioned above, in addition to organs UA, were performed at 24 hours. In vitro, caspases-(8/3) activity was tested in epithelial cells exposed to UA. RESULTS: Hemorrhagic shock increased organ (kidney and lung) TNF-α, MPO, and caspases activity in various patterns while caspase-8 remained elevated over time. Hemorrhagic shock led to increased plasma UA at 2 hours, which remained high until 72 hours; TNF-α and IL-18 were elevated at 24 hours. The exogenous UA administration in sham animals reproduced the activation of caspase-8 and MPO in organs, and TNF-α in the lung. The increased plasma and organ UA levels, plasma and lung TNF-α, as well as organ caspase-(8/3) and MPO, observed at 24 hours after HS, were prevented by the administration of Rasburicase during resuscitation. In vitro, soluble UA induced caspases-(3/8) activity in epithelial cells. CONCLUSION: Uric acid is persistently high after HS and leads to the activation of caspases-8 and organ inflammation; these can be prevented by an intervention to degrade UA. Therefore, UA is an important biomarker and mediator that could be considered a therapeutic target during HS resuscitation in human.

Patterns and predictors of emergency department visits among older patients after breast cancer surgery: A population-based cohort study.

OBJECTIVES: To characterize rates, reasons for, and associated predictors for emergency department (ED) visits after breast cancer (BC) surgery. METHODS: All women over 65 years undergoing curative surgery for non-metastatic incident BC (1998-2012) were identified using Quebec's universal healthcare administrative databases. Reasons for ED visits within 45days of operation were reported. Associated factors were estimated using Cox regression. RESULTS: Of 24,463 patients, 12.8% had postoperative ED visits. Most frequent reasons were: superficial infection, noninfectious gastrointestinal, trauma or wound (other than breast), noninfectious respiratory, and breast wound disruption. Significant predictors included localized (aHR, 1.24, CI 1.04-1.49) or regional disease (aHR 1.64, CI 1.41-1.92), mastectomy (aHR 1.22, CI 1.10-1.34), each operation before definitive oncologic control (aHR 1.12, CI 1.03-1.21), lower institutional volume (aHR 1.23, CI 1.09-1.38), having 6-10 prescriptions (aHR 1.23, CI 1.15-1.31) or >10 (aHR 1.53, CI 1.33-1.77), benzodiazepine use (aHR 1.09, CI 1.01-1.18), anticoagulant use (aHR 1.29, CI 1.13-1.46), cardiovascular disease (aHR 1.15, CI 1.05-1.26), diabetes (aHR 1.11, CI 1.00-1.24), past hospitalization (aHR 1.25, CI 1.17-1.34), and lower income (aHR 1.12, CI 1.04-1.20). CONCLUSION: Identification of risk factors in older patients before BC surgery could help prevent postoperative ED visits.

S100A8/A9 and sRAGE kinetic after polytrauma; an explorative observational study.

BACKGROUND: Following tissue injury after trauma, the activation of innate immune pathways results in systemic inflammation, organ failure and an increased risk of infections. The objective of this study was to characterize the kinetics of the S100A8/S100A9 complex, a new-recognized alarmin, as well as its soluble receptor sRAGE, over time after trauma as potential early biomarkers of the risk of organ damage. METHODS: We collected comprehensive data from consenting patients admitted to an ICU following severe trauma. The blood samples were taken at Day 0 (admission), Day1, 3 and 5 S100A8/A9 and sRAGE were measured by ELISA. Biomarkers levels were reported as median (IQR). RESULTS: Thirty-eight patients sustaining in majority a blunt trauma (89%) with a median ISS of 39 were included. In this cohort, the S100A8/A9 complex increased significantly over time (p = 0.001), but its levels increment over time (D0 to D5) was significantly smaller in patients developing infection (7.6 vs 40.1 mcg/mL, p = 0.011). The circulating level of sRAGE circulating levels decreased over time (p < 0.0001) and was higher in patients who remained in shock on day 3 (550 vs 918 pg/mL; p = 0.02) or 5 (498 vs 644 pg/mL; p = 0.045). Admission sRAGE levels were significantly higher in non-survivors (1694 vs 745 pg/mL; p = 0.015) and was higher in patients developing renal failure (1143 vs 696 pg/mL, p = 0.011). DISCUSSION: Our findings reveal an interesting association between the biomarker S100A8/9 least increase over time and the presence of infectious complication after trauma. We describe that the sRAGE decline over time is in relation with shock and markers of ischemic injury. We also confirm the association of sRAGE levels measured at admission with mortality and the development of renal failure. CONCLUSIONS: This work illustrates the importance of following the circulating level of biomarker overtime. The utilization of S1008/9 as a tool to stratify infection risk and trigger early interventions need to be validated prospectively.