Altered neutrophil activation in absence of IL-10 in a murine model of hemolytic uremic syndrome.

M CÓRDOBA MORENO,; R MEISS,; M PALERMO; B REARTE,; R FERNANDEZ-BRANDO; C ALBA-SOTO; GE. PINEDA; A BRUBALLA,; M ISTURIZ; MV RAMOS

Mar del Plata

Congreso; Reunión Anual de la SAI-SAIC-SAFE; 2016

Sociedad Argentina de Inmunologia

HemolyticUremic Syndrome (HUS), is a systemic disease caused by circulating Shiga-toxin (Stx) which mainly damages kidney. Besides Stx2,inflammatory response mediated by neutrophils (PMN) is essential to HUS evolution. We have demostrated that micelacking IL-10 (IL-10-/-) had a higher survival rate to Stx2 thancontrols. The aim of the work was to determine the role of PMN in HUS evolutionin absence of IL-10.  Before and 24h, 48h and 72h afterof 1LD100 of Stx2 e.v., IL-10-/- and controlmice were sacrificed. Total leukocytes were counted and PMN were identified asLy6G+CD11b+ cells in blood and bone marrow. PMN production of reactive oxygen species (ROS)was evaluated without stimulus (basal) or after PMA stimulation, with DHR byFACS. In basal condition both strains showed similarabsolute number of PMN in blood, although the percentage of PMN in bone marrowwas increased in IL-10-/- mice (%PMN:IL-10-/-= 52.8±4.1,control=39.9±1.9*,*p<0.05).Circulating PMN increased at 48h post-Stx2 in controls, meanwhile it wasdelayed at 72h in IL-10-/- mice (PMN(105/ml): Basal/Stx2:IL-10-/-(72h)=10.9±1.6/31.7±5.0*,control(48h)=8.5±1.2/16.4±3.3*,*p<0.05 vsbasal). Peripheral PMN  upregulated CD11bexpression 48h after Stx2 in control mice but no changes were observed in IL-10-/-mice at any time, (MFI Basal/Stx (48h):IL-10-/-:906±106/662±241; control=408±84/1780±100*,*p<0.05).In contrast as it was reported for control mice, unstimulated PMN from IL-10-/-mice  showed similar ROSproduction before (0h) and 72h after Stx2 (MFI of DHR:0h=7.0±0.5;72h=5.4±0.8),and in vitro PMA activation wasconserved (0h=23.3±5.7*;72h=31.0±6.2*,*p<0.05 vs respective time).IL10-/-mice had  a delayedneutrophilia in response to Stx2. Moreover, even though these PMN did notshowed in vivo activation(upregulation of CD11b and ROS production), they are capable to produceoxidative burst upon in vitro PMA-stimulation. These alterations could beresponsible for  the increased survival afterStx2.