Marita Marengo

Detrimental cross-talk between sepsis and acute kidney injury: new pathogenic mechanisms, early biomarkers and targeted therapies

This article is one of ten reviews selected from the Annual Update in Intensive Care and Emergency medicine 2016. Other selected articles can be found online at http://www.biomedcentral.com/collections/annualupdate2016. Further information about the Annual Update in Intensive Care and Emergency Medicine is available from http://www.springer.com/series/8901.

Extracorporeal Treatments in Patients with Acute Kidney Injury and Sepsis

Acute kidney injury (AKI) is one of the most common sepsis complications, and AKI development increases the risk of sepsis episodes by affecting host immune competence. The concomitance of these 2 clinical syndromes is associated with an extremely poor prognosis with mortality rates ranging from 50 to 70%. These unacceptable outcomes reflect the poor knowledge of the underlying pathogenic mechanisms and the lack of appropriate diagnostic and therapeutic methodologies as well as of appropriate experimental models. However, in recent years new insights have revolutionized the scientific and clinical approach to sepsis-induced AKI (S-AKI) leading to encouraging results. The aim of this paper is to review the extracorporeal treatment of S-AKI with a focus on the most promising experimental techniques and the underlying molecular mechanisms.

Blood Purification for Sepsis

Abstract There is currently a clear biologic rationale for blood purification used in sepsis. Immunomodulation and organ support play important roles in the application of blood purification. Conventional continuous venovenous hemofiltration and hemodialysis have been shown not to be effective in sepsis in the absence of concomitant acute renal failure. Plasma therapies, high-volume hemofiltration, hemadsorption, or combinations of these therapies appear promising. However many questions still remain unanswered. Current technologies still remain inadequate for the removal of middle-molecular-weight substances, and the current practice worldwide is extremely variable. Moreover, there is lack of large-scale randomized clinical trials. Recently, new developing technologies may enhance the clinical results of current RRT strategies, including high-porosity of membranes to improve middle molecular clearance. Finally, multicenter randomized controlled trials are needed to test these promising blood purification technologies.

Acute Kidney Injury and Chronic Kidney Disease in the Elderly and Polypharmacy

Background: Acute kidney injury (AKI) incidence is reported to be 10 times higher in aged people. Related to their higher prevalence of chronic kidney disease (CKD), older patients are at high risk of toxic effects driven by drugs. Methods: The demographics, hospitalizations, visits to the Emergency Department, pharmacological therapy, and lab tests were analyzed in 71,588 individuals. Results: Data showed a higher prevalence of AKI as well as CKD in the elderly as compared to the younger group, with an associated very high mortality. A broad number of drugs was prescribed, ranging from 1 to 35, the majority being between 5 and 9 drugs. Conclusion: Elderly patients who developed AKI had a higher number of hospitalizations (underlying frailty), were more likely to progress to more severe stages of CKD and to be affected by other non-renal pathologies (associated comorbidities) and to be given heavier pharmacological prescriptions (polypharmacy).

Perfluorocarbon solutions limit tubular epithelial cell injury and promote CD133+ kidney progenitor differentiation: potential use in renal assist devices for sepsis-associated acute kidney injury and multiple organ failure

Background The renal assist device (RAD) is a blood purification system containing viable renal tubular epithelial cells (TECs) that has been proposed for the treatment of acute kidney injury (AKI) and multiple organ failure. Perfluorocarbons (PFCs) are oxygen carriers used for organ preservation in transplantation. The aim of this study was to investigate the effect of PFCs on hypoxia- and sepsis-induced TEC injury and on renal CD133+ progenitor differentiation in a microenvironment similar to the RAD. Methods TECs were seeded in a polysulphone hollow fibre under hypoxia or cultured with plasma from 10 patients with sepsis-associated AKI in the presence or absence of PFCs and were tested for cytotoxicity (XTT assay), apoptosis (terminal deoxynucleotidyl transferase dUTP nick end labeling assay, caspases, enzyme-linked immunosorbent assay, Fas/Fas Ligand pathway activation), mitochondrial activity, cell polarity [transepithelial electrical resistance (TEER)] and adenosine triphosphate production. The effect of PFCs on proliferation and differentiation of human CD133+ progenitors was also studied. Results In the presence of PFCs, TECs seeded into the polysulphone hollow fibre showed increased viability and expression of insulin-like growth factor 1, hepatocyte growth factor and macrophage-stimulating protein. Plasma from septic patients induced TEC apoptosis, disruption of oxidative metabolism, alteration of cell polarity and albumin uptake, down-regulation of the tight junction protein ZO-1 and the endocytic receptor megalin on the TEC surface. These detrimental effects were significantly reduced by PFCs. Moreover, PFCs induced CD133+ renal progenitor cell proliferation and differentiation towards an epithelial/tubular-like phenotype. Conclusions PFCs improved the viability and metabolic function of TECs seeded within a polysulphone hollow fibre and subjected to plasma from septic AKI patients. Additionally, PFCs promoted differentiation towards a tubular/epithelial phenotype of CD133+ renal progenitor cells.