Selective renal blood perfusion induces renal tubules injury in a porcine model

Polyethylene Oxide Molecular Size Determines the Severity of Atypical Thrombotic Microangiopathy in a Guinea Pig Model of Acute Intravenous Exposure

In 2017, Opana ER was voluntarily removed from the U.S. market based on concerns that its risks outweighed its therapeutic benefits. The data that supported this conclusion were based on postmarketing evaluation that demonstrated increased intravenous abuse associated outbreaks of HIV, hepatitis C, and uniquely, a thrombotic thrombocytopenic purpura (TTP)-like syndrome. In 2017, the cause was mechanistically linked to intravenous exposure of the high-molecular weight polyethylene oxide (PEO), an excipient component of the drug product. However, it was unknown how differing PEO preparations might alter this response in vivo. Knowing the likelihood of a PEO driven atypical thrombotic microangiopathy with hemolytic uremic syndrome (TMA-HUS), this study was specifically designed with the primary objective focused on understanding the impact of PEO molecular weight on TMA-HUS in a guinea pig model of acute repeat PEO (1, 4, and 7 MDa) dosing. Results from this analysis suggest that repeated dosing with PEO 4 and 7 MDa, but not 1 MDa induced a marked intravascular hemolysis with schistocytes, mild anemia, thrombocytopenia, hemoglobinuria, and kidney injury, consistent with observations of a TMA-HUS-like syndrome. Nonetheless, observations of tissue microthrombi, complement or altered von Willebrand factor involvement were not observed, which would be consistent with a definitive TMA. Further, only 7 MDa PEO dosing was associated with marked renal hypoxia. Taken together, this study defines renal injury risk with PEO formulations >1 MDa that is driven by a robust intravascular hemolysis and potentially, tissue hypoxia.

Kidney protection in thoracoabdominal aortic aneurysm surgery

Acute kidney injury (AKI) is a common complication of both open and endovascular repair of thoracoabdominal aortic aneurysms (TAAA). Its definition varies across difference studies, some standardized definitions (RIFLE, AKIN, KDIGO) have been proposed but still not uniformly employed in published papers. Acute kidney injury is multifactorial and is associated with increased in-hospital mortality, long-term mortality and late renal function decline. In addition, AKI is also associated with perioperative spinal cord ischemia. No specific pharmacological strategy has received a strong recommendation with high level of evidence as a protective measure. Fenoldopam, methylprednisolone or mannitol use to prevent AKI is commonly employed, but not supported by literature data. Avoiding nephrotoxic drugs and maintaining an adequate MAP, during and after the procedure plays a key role in preserving kidney function. During open TAAA surgery, renal arteries may be reimplanted using different techniques. The choice of the best option must be tailored to the patient, to reduce ischemic time and guarantee long-term patency. Current experience suggests that cold crystalloid solutions are the best substrates in preventing ischemia-reperfusion injury. Renal perfusion using Custodiol^® (Dr Franz-Kohler Chemie GmbH; Bensheim, Germany) 4 °C, even if currently considered off-label, represents an encouraging organ protection tool. In endovascular TAAA repair, techniques such as fusion imaging, use of diluted contrast, and CO<inf>2</inf> subtraction angiography have the potential to reduce postoperative AKI. Visceral vessels patency is closely related to the anatomy. Therefore, accurate endograft design according to these characteristics is crucial for long-term preservation of renal function.

Comparison of urine and serum neutrophil gelatinase-associated lipocalin after open and endovascular thoraco-abdominal aortic surgery and their meaning as indicators of acute kidney injury

BACKGROUND

Neutrophil gelatinase-associated lipocalin (NGAL) has been described as a potential biomarker of acute kidney injury (AKI) in different settings, but its behaviour under influence of open and endovascular repair of thoraco-abdominal aortic aneurysms (TAAA) has not been assessed yet. In this study, the course of NGAL was observed and differences of serum- (sNGAL) and urine-NGAL (uNGAL) levels following TAAA repair, especially with regard to AKI, were evaluated.

PATIENTS AND METHODS

In this retrospective single centre study, 52 patients (mean age 64.5 years, [43-85 years]), including 39 (75 %) men, were enrolled (2014-2015, 13.2 months mean follow-up). Levels of sNGAL and uNGAL were measured perioperatively for 48 hours on intensive care unit. Twenty-three patients were treated by endovascular and 29 by open TAAA-repair.

RESULTS

Logistic regression revealed an increase in NGAL (sNGAL p = 0.0263, uNGAL p = 0.0080) corresponding with an increase in serum creatinine within the first 48 hours. Fourteen patients (26.9 %) developed AKI and 11 (21.1 %) required dialysis. The course of NGAL differed significantly (uNGAL p < .0001, sNGAL p = 0.0002) between patients suffering from AKI requiring dialysis and patients without AKI. The predictive power of uNGAL was three times higher than that of sNGAL (estimate of the regression slope 0.1382 vs. 0.0460). No significant difference between patients undergoing open or endovascular TAAA repair regarding the perioperative course of sNGAL and uNGAL was observed.

CONCLUSION

serum-NGAL and urine-NGAL correlate with serum creatinine levels and AKI requiring dialysis. Furthermore, the postoperative course of sNGAL and uNGAL after open and endovascular TAAA repair is not significantly different. Taken together, the results indicate that uNGAL and, to a lesser extent, sNGAL could be considered biomarkers for early detection of perioperative AKI after open and endovascular TAAA surgery.

Psychosocial Stress and Immunity-What Can We Learn From Pig Studies?

Psychosocial stress may impair immune functions and provoke the development of pathologies. The underlying communication between the brain and the immune system is being studied predominantly in rodents. However, pigs offer several advantages as preclinical models for humans because pigs are more similar to humans than rodents in many anatomical and physiological characteristics. Unlike in rodents, the main stress-induced glucocorticoid in humans and pigs is cortisol with a similar circadian rhythm. In this study, we summarize data on short-term and long-term effects of social stress in pigs for their immunity and neuroendocrine regulation with consequences for their health and well-being. As typical social stressors, regrouping, crowding, social isolation, and maternal deprivation have been studied. Psychosocial stress in pigs may affect various reactions of innate and adaptive immunity, such as leukocyte distribution, cytokine secretion, lymphocyte proliferation, and antibody production as well as immune responses to viral infection or vaccination. Furthermore, social stress may induce or promote gastrointestinal diseases through dysregulation of inflammatory processes. In piglets, psychosocial stress may also result in glucocorticoid resistance of lymphocytes, which has been discussed as a cause of allergic asthma in humans. Stress-related neuroendocrine alterations in the cortico-limbic structures, such as the prefrontal cortex, amygdala, hippocampus and hypothalamus, have been demonstrated in pigs at different ages. Based on these data, we propose using pigs as models for psychosocial stress in humans to study the mechanisms of brain-to-immune and immune-to-brain communication from the systemic level down to the cellular and subcellular levels.