RESUMEN
Extracellular DNA (ecDNA) activates immune cells and is involved in the pathogenesis of diseases associated with inflammation such as sepsis, rheumatoid arthritis or metabolic syndrome. DNA can be cleaved by deoxyribonucleases (DNases), some of which are secreted out of cells. The aim of this experiment was to describe plasma DNase activity in relation to extracellular DNA in adult rats, to analyse potential sex differences and to prove whether they are related to endogenous testosterone. Adult Lewis rats (n=28) of both sexes were included in the experiment. Male rats were gonadectomized or sham-operated and compared to intact female rats. Plasma ecDNA and DNase activity were measured using fluorometry and single radial enzyme diffusion assay, respectively. Concentrations of nuclear ecDNA and mitochondrial ecDNA were determined using real-time PCR. Females had 60% higher plasma DNase activity than males ( p=0.03). Gonadectomy did not affect plasma DNase in males. Neither the concentration of total ecDNA, nor nuclear or mitochondrial DNA in plasma differed between the groups. No significant correlations between DNase and ecDNA were found. From previous studies on mice, it was expected, that male rats will have higher DNase activity. In contrast, our study in rats showed the opposite sex difference. This sex difference seems not to be caused by endogenous testosterone. Interestingly, no sex differences were observed in plasma ecDNA suggesting a complex or missing association between plasma ecDNA and DNase. The observed sex difference in plasma DNase should be taken into account in animal models of ecDNA-associated diseases.
Asunto(s)
ADN/sangre , Desoxirribonucleasas/sangre , Caracteres Sexuales , Animales , Femenino , Masculino , Orquiectomía , Ratas Endogámicas Lew , Testosterona/sangreRESUMEN
The aim of this study was to investigate the potential of extracellular DNA as a prognostic and/or therapeutic target in inflammatory bowel disease. Fifty male C57BL/6J mice were used in the experiment. Acute colitis was induced by intake of 2% dextran sulphate sodium (DSS) for seven days followed by three days of water intake. DNase I was injected intravenously on days 3 and 7. Plasmatic levels of extracellular DNA (ecDNA) were measured on days 6 and 10. Weight loss, stool consistency and liquid intake were monitored throughout the experiment. Colon length and weight, myeloperoxidase activity and tumour necrosis factor α (TNF-α) levels were measured at sacrifice. DSS-treated mice displayed severe colitis, as shown by disease activity parameters. Both groups with colitis (DNase treated and untreated) had significantly poorer weight loss, colon length and stool consistency compared with control groups on water. No differences between the DNasetreated and untreated DSS groups were recorded. Myeloperoxidase activity and levels of TNF-α in colonic tissue were notably greater in both groups with colitis compared to controls. In addition, both biochemical markers were improved in the DNasetreated group with colitis compared to the untreated group. Although the disease activity was proved by several independent parameters in both groups with colitis, levels of ecDNA did not show any difference between the groups throughout or at the end of experiment. The role of ecDNA in experimental colitis has not been confirmed. However, DNase I injection resulted in some improvement, and thus should be studied in more detail.