Free p-Cresol Alters Neutrophil Function in Dogs

Abstract

To achieve a clearer understanding of the mechanisms responsible for neutrophil dysfunction recently described in dogs with chronic renal failure (CRF), the plasma concentrations of free p-cresol in healthy dogs (n = 20) and those with CRF (n = 20) were compared. The degree of correlation was determined between plasma levels of p-cresol and markers of oxidative stress and function of neutrophils in these dogs. The effect of this compound on oxidative metabolism and apoptosis was assessed in neutrophils isolated from 16 healthy dogs incubated in RPMI 1640 supplemented with p-cresol (0.405 mg/L) and compared with medium supplemented with uremic plasma (50%). To achieve this, the plasma concentration of p-cresol was quantified by liquid phase high-performance liquid chromatography. The neutrophil oxidative metabolism was determined using the probes hydroethidine and 2',7'-dichlorofluorescein diacetate and apoptosis was measured using Annexin V-PE by capillary flow cytometry. Compared with the healthy dogs, uremic dogs presented higher concentrations of free p-cresol, greater oxidative stress, and neutrophils primed for accelerated apoptosis. The free p-cresol induced in neutrophils from healthy dogs increased apoptosis and decreased reactive oxygen species production. We conclude that the health status presented during uremia concomitant with the increase in plasma free p-cresol can contribute to the presence of immunosuppression in dogs with CRF.

The uremic toxin methylguanidine increases the oxidative metabolism and accelerates the apoptosis of canine neutrophils

“…The hematological and biochemical profiles of healthy dogs were in accordance with the normal values of the species (Thrall et al, 2004), certifying the good health of these dogs. Laboratory and clinical changes observed in uremic dogs were similar to those recently described (Almeida et al, 2013b;Bosco et al, 2016) and were equivalent to stage 4, according to IRIS staging (IRIS, 2015).…”

“…Although the CKD is common in dogs, few studies demonstrating the effect of uremic toxins on neutrophil function are available and to date we have found no studies on MG in this species. Recently, our research group demonstrated increased plasma concentration of p-cresol in uremic dogs and the involvement of this toxin in neutrophil oxidative metabolism inhibition and increased apoptosis (Bosco et al, 2016). Similar studies in humans generated new important contributions to guide therapies and the development of more efficient hemodialysis membranes (Hedayat et al, 2013;Nakabayashi et al, 2011).…”

“…Neutrophil oxidative metabolism and apoptosis were evaluated according to previously described methodology (Bosco et al, 2016). Briefly, neutrophils isolated in double gradient were diluted (10 6 /mL) in RPMI 1640 medium (Sigma-Aldrich Co., St. Louis, USA).…”

“…It is generally accepted that in human chronic kidney disease (CKD), neutrophil function is affected, contributing to increased mortality due to bacterial infections (Cohen and Hörl, 2012). Similarly to that reported in humans, recent studies have shown alterations in neutrophil oxidative metabolism and oxidative stress in dogs with CKD (Almeida et al, 2013a,b;Bosco et al, 2016;Silva et al, 2013). However, the mechanisms and relationships between neutrophil dysfunction and oxidative stress in dogs with CKD have not been fully elucidated.…”

Hemólise interfere na mensuração dos biomarcadores plasmáticos de estresse oxidativo em cães

“…Valores plasmáticos de TAC e TOC utilizando a mesma metodologia e equipamento são restritos a estudos experimentais com pequeno tamanho amostral (Almeida et al, 2013). Os valores de normalidade dos biomarcadores de estresse oxidativo estabelecidos no presente estudo foram similares e apresentaram menor amplitude que os descritos na literatura (Almeida et al, 2013;Bosco et al, 2016), exceto o ácido úrico. Essa diferença quanto ao valor médio de ácido úrico e o intervalo de confiança de todos os biomarcadores de estresse oxidativo reforçam a orientação de que cada laboratório deve estabelecer seus próprios valores de referência para adequada interpretação e controle de qualidade.…”