The IL-10 participation in the induced-endotoxins bacterial tolerance/immunosuppression

MARLINA CÓRDOBA MORENO; ADRIANA FONTANALS; ANDREA MAGLIOCO; DAIANA MARTIRE-GRECO; NAHUEL RODRIGUEZ-RODRIGUES; VERÓNICA LANDONI; GABRIELA FERNANDEZ; MARTÍN ISTURIZ; BÁRBARA REARTE

Medellin

Congreso; INMUNOCOLOMBIA 2015- XI Congreso de la Asociación Latinoamericana de Inmunología (ALAI)-X Congreso Colombiano de Alergia Asma e Inmunología (ACAAI); 2015

Congreso de la Asociación Latinoamericana de Inmunología (ALAI)-X Congreso Colombiano de Alergia Asma e Inmunología (ACAAI)

Introduction: Septic processes constitute one of the major causes of death in intensive care units reaching a mortality rate of 30% in Europe as well as in countries such as the US. Even though sepsis presents a simultaneous induction of both an inflammatory and anti-inflammatory response, in early phases predominates a hyper-inflammatory state whereas during later phases an anti-inflammatory response becomes predominant. It is during this last state that more than 70% of sepsis deaths occur due to failure in controlling pathogens associated to an immunosuppression state. In Sepsis caused by Gram-negative bacteria, endotoxins, a normal constituent of the bacterial outer wall, also known as lipopolysaccharide (LPS), has been considered one of the principal agents causing the undesirable effects in this critical illness. The response to LPS involves a rapid secretion of both mediators proinflammatory as well as anti-inflammatory. Exposure of the host to repeated LPS dose induces a state of hyporesponsiveness to subsequent simulations, in a process known as LPS or endotoxins tolerance. Although it is recognized as a protective mechanism to avoid systemic inflammation, LPS tolerance has also been suggested as the main cause of the non-specific immunosuppression described in these patients. Numerous mediators have been proposed as causative factors of immunosuppression in sepsis such as anti-inflammatory cytokines (e.g.IL-10 and TGF-beta), as well as glucocorticoids among others. Recently we demonstrated that glucocorticoids play a substantial role in the LPS induced immunosuppression in murine models. Objective: The aim of this work is to evaluate the contribution of other agents involved in the induction and/or maintenance of the immunosuppression induced by LPS in a murine model such as the anti-inflammatory cytokines IL-10 participation and its potential relationship with glucocorticoids. Methods: Wild type (WT) and IL-10 deficient (KO) BALB/c mice were treated with different LPS doses (1, 5, 10 and 200ug/mouse) to assess their sensibility to endotoxin. Also, after the 200ug LPS challenge cytokines production (e.g. TNF-α and IL-10), and corticosterone levels were analyzed. Finally, we evaluated the effect of the treatment with exogenous glucocorticoids (e.g. dexamethasone (Dex)), before the (LPS 5ug and LPS 200ug/ mouse) LPS challenge in both mice strains. We also evaluated the possibility to establish an endotoxin tolerance/immunosuppression state in KO mice. For this, the mice were daily treated with increasing doses of LPS. Cytokines kinetics such as TNF-α and corticosterone levels in plasma were measured. In addition, tolerized/immunosuppressed mice were immunized with sheep red bloodcells. The immune response analyzing the antibody title was evaluated on day 7 by means of flow cytometry and hemagglutination assay. Results: Clearly the KO mice were extremely more sensitive to the LPS challenge than the WT mice. Thus, the lethal dose for the KO mice was around to 5-10ug per mouse, whereas for the WT mice was 40 times larger (i.e. about 200ug per mouse) (mortality rate with LPS 10ug: wt 0/8; KO 8/8). In the WT mice a peak in IL-10 and TNF-α secretion was observed at 1.5 hours after the LPS 200ug inoculation and remained elevated up to 6 hours for IL-10, while the values of TNF-α returned to baseline levels after 3 hours . In the KO mice the production kinetics of TNF-α it behaved completely different to that observed in WT. Not only the secretion peak at 1.5 hours showed a significant almost 2 fold increase difference than in the WT mice (mean ± SEM TNF-α production 1.5 hours after LPS (pg/ml): WT= 2505±410, KO= 3788±60; p