Model of polymicrobial peritonitis that induces the proinflammatory and immunosuppressive phases of sepsis.

Severe sepsis is associated with early release of inflammatory mediators that contribute to the morbidity and mortality observed during the first stages of this syndrome. Although sepsis is a deadly, acute disease, high mortality rates have been observed in patients displaying evidence of sepsis-induced immune deactivation. Although the contribution of experimental models to the knowledge of pathophysiological and therapeutic aspects of human sepsis is undeniable, most of the current studies using animal models have focused on the acute, proinflammatory phase.

Hypothesis: an alternative pathway for the regulation of inflammation.

Regulation of inflammation is a crucial event since its alteration, such as in sepsis and chronic autoimmune (i.e. rheumatoid arthritis, lupus erythematosus) or infectious diseases (i.

Macrophage depletion following liposomal-encapsulated clodronate (LIP-CLOD) injection enhances megakaryocytopoietic and thrombopoietic activities in mice.

Megakaryocytopoiesis is the cellular process by which stem cells progress through commitment, proliferation and differentiation, leading to the production of platelets. In the mouse, this process is accomplished within the bone marrow (BM) and spleen microenvironment and is carried out by regulatory molecules and accessory cells, including macrophages, fibroblasts and endothelial-like cells. Previously, we demonstrated that specific macrophage depletion, using liposomal-encapsulated clodronate (LIP-CLOD), induced a rapid recovery of the platelet count in a mouse model of immune thrombocytopenia.

Soluble fibrinogen modulates neutrophil functionality through the activation of an extracellular signal-regulated kinase-dependent pathway.

The integrin family not only mediates the recruitment of polymorphonuclear leukocytes (PMN) to sites of inflammation but also regulates several effector functions by binding to specific ligands. We have recently demonstrated that soluble fibrinogen (sFbg) is able to trigger an activating signal in PMN through an integrin-dependent mechanism. This activation results in degranulation, phagocytosis enhancement, and apoptosis delay.

Rapid recovery of platelet count following administration of liposome-encapsulated clodronate in a mouse model of immune thrombocytopenia.

Immune thrombocytopenic purpura (ITP) is a haematological disorder characterized by increased platelet consumption. The destruction of platelets is mediated by the reticulo-endothelial system (RES), particularly by splenic and hepatic macrophages. Previously, we demonstrated in a mouse model of thrombocytopenia that the depletion of these cells by liposome-encapsulated clodronate (LIP-CLOD) induces the recovery of the platelet count.