Adipose-derived mesenchymal stromal cells primed by macrophages decrease inflammation and multiple organ lesions improving mice survival after cecal ligation and puncure-induced sepsis

Abstract

Background & Aim Sepsis is a life-threatening illness and a public health issue due to its high frequency, its high annual cost and the increase of bacterial resistance to antibiotics. Sepsis results from an overwhelming inflammatory host response to infection that can lead to organ failure. Attenuation of the inflammation could be a new therapeutic approach. In the last few years, mesenchymal stromal cells (MSCs) and in particular adipose-derived mesenchymal stromal cells (ASCs) have been considered as a new therapeutic for sepsis. Indeed, ASCs modulate immune response and therefore could decrease general inflammation. Our recent study demonstrated that contact with pro- (M1-MΦ) or anti-inflammatory (M2-MΦ) macrophages modulate the immunosuppressive capacities of MSCs in vitro. Therefore, the objective of this study was to determine the effect of different human MΦ-primed ASCs in a model of sepsis induced by cecal ligation and puncture (CLP) in C57BL/6 mice. Methods, Results & Conclusion Human adipose-derived mesenchymal stromal cells were co-cultivated with human pro-inflammatory (M1-MΦ) or with anti-inflammatory (M2-MΦ) macrophages. After 24 h of co-culture, cells were harvested and ASCs and macrophages were magnetically separated based on CD45 expression. Sepsis is induced by cecal ligation and puncture in C57/BL6 mice and ASCs or MΦ-primed ASCs were injected in the peritoneal cavity right after the ligation. Then, survival is assayed every 6h for 5 days and general and local inflammation were evaluated 24h and 48h post-CLP. The intraperitoneal injection of Mφ-primed ASCs and especially M1-primed ASCs significantly increases the survival rate compared to unprimed-ASCs. Indeed, 70% of the M1-ASCs-treated mice survived 5 days post-CLP whereas 30% survived in the PBS-treated group. Moreover, injection of MΦ-primed ASCs decrease organ damage that is associated with the modification of recruited immune cells in the organs. MΦ-primed ASCs also modified the immune response in the peritoneal cavity, maintaining macrophage population in the cavity. Finally, M1-primed ASCs restore normal plasma level of lactate and decrease general inflammation. Altogether, our results suggest that MΦ-primed ASCs modulated modifies the immune response after sepsis and are more protective than the injection of unprimed ASCs. Therefore, MΦ-primed ASCs, associated to antibiotics, could improve the clinical outcomes in patients with sepsis. Sepsis is a life-threatening illness and a public health issue due to its high frequency, its high annual cost and the increase of bacterial resistance to antibiotics. Sepsis results from an overwhelming inflammatory host response to infection that can lead to organ failure. Attenuation of the inflammation could be a new therapeutic approach. In the last few years, mesenchymal stromal cells (MSCs) and in particular adipose-derived mesenchymal stromal cells (ASCs) have been considered as a new therapeutic for sepsis. Indeed, ASCs modulate immune response and therefore could decrease general inflammation. Our recent study demonstrated that contact with pro- (M1-MΦ) or anti-inflammatory (M2-MΦ) macrophages modulate the immunosuppressive capacities of MSCs in vitro. Therefore, the objective of this study was to determine the effect of different human MΦ-primed ASCs in a model of sepsis induced by cecal ligation and puncture (CLP) in C57BL/6 mice. Human adipose-derived mesenchymal stromal cells were co-cultivated with human pro-inflammatory (M1-MΦ) or with anti-inflammatory (M2-MΦ) macrophages. After 24 h of co-culture, cells were harvested and ASCs and macrophages were magnetically separated based on CD45 expression. Sepsis is induced by cecal ligation and puncture in C57/BL6 mice and ASCs or MΦ-primed ASCs were injected in the peritoneal cavity right after the ligation. Then, survival is assayed every 6h for 5 days and general and local inflammation were evaluated 24h and 48h post-CLP.