Neutrophil-Derived Circulating Free DNA (cf-DNA): an associated marker for Hemolytic Uremic Syndrome development.

RAMOS, MV;; MEJIAS, MP; SABBIONE, F; ABREY-RECALDE, MJ; FERNANDEZ-BRANDO,RJ;; AMARAL, MM; EXENI, R; TREVANI, A; PALERMO, MS

Mar del Plata

Congreso; LIX Reunión Científica Anual de la Sociedad Argentina de Investigación Clínica y LXII Reunión Científica Anual de la Sociedad Argentina de Inmunología; 2014

Sociedad Argentina de Inmunología,

Hemolytic Uremic Syndrome (HUS), a vascular disease characterized by hemolityc  anemia, thrombocitopenia  and acute  renal failure  is caused by enterohemorraghic Shiga toxins (Stx)-producing bacteria. Besides Stx, inflammatory response mediated by neutrophils (PMN) is essential to HUS evolution. PMN have the capacity to release "neutrophil extracellular traps" (NETs) which are involved in the pathogenesis of several diseases. NETs are composed of neutrophil-derived circulating free DNA (cf-DNA), histones and PMN proteins such as proteases. The aim of this work was to investigate the presence of cf-DNA in HUS patients. We observed increased values of cf-DNA in plasma from HUS compared to healthy children (HC) ((HC:5,1±0,5; HUS:10±0,5*)ug/ml, n=15, *p<0,05). Moreover, we observed by confocal microscopy that DNA colocalized with myeloperoxidase in HUS plasma. These data and our previous results showing that Stx induces NETosis in PMN, suggest that increased cf-DNA found in HUS plasma could be due to NETosis produced by in patients.To investigate whether HUS PMN have an altered NETosis  capacity,  isolated peripheral PMN from HUS and HC were incubated with medium or  phorbol myristate acetate (PMA), as positive control. After 4h, extracellular DNA and elastase activity were measured in the supernatants. No differences were found between both groups (DNA(ug/ml)=Basal (HC:1,2±0,1;HUS:1,1±0,2); PMA (HC:2,6±0,3;HUS:2,8±0,1); (Elastase(AU)=Basal (HC: 0,6±0,1; HUS:0,7±0,2); PMA (HC:1,1±0,3;HUS:1,2±0,3), n=5. Isolated HUS PMN did not exhibit failure or exacerbation of their capacity to produce NETs. Whereas physiologic amounts of NETs are important in anti-infectious innate immune responses, aberrantly high levels of cf-DNA in circulation might also result in pathophysiologic conditions such as clotting of capillaries, impairment of microcirculation in the renal microvasculature, and tissue damage. In this way, PMN could contribute to inflammatory response in HUS patients