[An overview on acute kidney injury in COVID-19].

SARS-CoV-2 infection is responsible for the coronavirus disease 2019 (COVID-19). In the complex scenario of COVID-19, it is also possible to find patients with renal damage. The pathogenesis is multifactorial and not unique, and the clinical presentation may include urinary alterations, such as proteinuria and hematuria, accompanied with reduced renal function, or not. Acute kidney injury (AKI) is not uncommon, especially among critically ill patients hospitalized in intensive care unit. AKI is a negative prognostic factor and is associated with high in-hospital mortality. An early diagnosis of AKI and the assessment of any risk factors allow the nephrologist to implement appropriate therapeutic strategies, such as pharmacological or extracorporeal support. Still, mortality in patients with AKI during COVID-19 remains high. COVID-19 AKI is a quickly evolving field of study.

Evidence that p-cresol and IL-6 are adsorbed by the HFR cartridge: towards a new strategy to decrease systemic inflammation in dialyzed patients?

INTRODUCTION: Hemodialysis (HD) and hemodiafiltration clear only with a low efficiency the plasma from interleukin-6 and p-cresol, two protein-bound uremic toxins associated with high cardiovascular risk in end stage renal disease. HFR Supra is a double-chamber hemodiafiltration system in which the ultrafiltrate returns to the patient after its regeneration through a resin cartridge that binds hydrophobic and protein-bound solutes. In the present study, we evaluated whether the HFR cartridge can also bind total p-cresol and IL-6 and remove them from the ultrafiltrate. METHODS: We compared the levels of IL-6 and p-cresol in ultrafiltrate samples collected at the inlet (UFin) and at the outlet (UFout) of the cartridge at the start or at the end of a 240 min HFR session in 12 inflamed chronic HD patients. The pro-inflammatory activity of the ultrafiltrate samples was also determined by evaluating the changes that they induced in IL-6 mRNA expression and protein release in peripheral blood mononuclear cells from 12 healthy volunteers. IL-6 and p-cresol circulating levels were also assessed in peripheral plasma blood samples collected before and after HFR and, for comparison, a control HD. RESULTS: p-Cresol and IL-6 were lower in UFout than in UFin both at the start and at the end of the HFR session, suggesting that they were retained by the cartridge. IL-6 mRNA expression and release were lower in PBMC incubated with UFout collected at the end than with UFin collected at the start of HFR, suggesting that passage through the cartridge reduced UF pro-inflammatory activity. Plasma total p-cresol decreased by about 53% after HFR, and 37% after HD. IL-6 circulating values were unmodified by either these dialysis procedures. CONCLUSIONS: This study shows that the HFR-Supra cartridge retains total p-cresol and IL-6 in the ultrafiltrate and lowers plasma total p cresol but not IL-6 levels. TRIAL REGISTRATION: ClinicalTrials.gov NCT01865773.