Abstract
Lipopolysaccharide (LPS) is commonly used in murine sepsis models, which are largely associated with immunosuppression and collapse of the immune system. After adapting the LPS treatment to the needs of locally bred BALB/c mice, the present study explored the protective role of Micrococcus luteus peptidoglycan (PG)-pre-activated vaccine-on-chip technology in endotoxemia. The established protocol consisted of five daily intraperitoneal injections of 0.2μg/g LPS, allowing longer survival, necessary for a therapeutic treatment application. A novel immunotherapy technology, the so-called vaccine-on-chip, consists of a 3-dimensional laser micro-textured silicon (Si) scaffold loaded with macrophages and activated in vitro with 1μg/ml PG, which has been previously shown to exert a mild immunostimulatory activity upon subcutaneous implantation. The LPS treatment significantly decreased CD4 + and CD8 + cells, while increasing CD11b + , Gr1 + , CD25 + , Foxp3 + , and class II + cells. These results were accompanied by increased arginase-1 activity in spleen cell lysates and C-reactive protein (CRP), procalcitonin (PCT), IL-6, TNF-a, IL-10, and IL-18 in the serum, while acquiring severe sepsis phenotype as defined by the murine sepsis scoring. The in vivo application of PG pre-activated implant significantly increased the percentage of CD4 + and CD8 + cells, while decreasing the percentage of Gr1 + , CD25 + , CD11b + , Foxp3 + cells, and arginase-1 activity in the spleen of LPS-treated animals, as well as all serum markers tested, allowing survival and rescuing the severity of sepsis phenotype. In conclusion, these results reveal a novel immunotherapy technology based on PG pre-activated micro-texture Si scaffolds in LPS endotoxemia, supporting thus its potential use in the treatment of septic patients.
Highlights
Sepsis is a polyparametric condition, which back in the early ‘90s was defined as a systematic inflammatory response resulting in a variety of severe clinical symptoms [1], early in 2001 it was defined as “infection” [2] and today it is defined as life-threatening organ dysfunction caused by dysregulated response of the host to infection [3]
Sepsis is being considered as an immunosuppressive disorder and immunostimulatory therapies are envisaged as potential treatments
Among the various experimental models, the present study focused on the LPS-induced endotoxemia model that displayed major sepsis-related immunosuppressive and inflammatory markers and survived long enough to allow application of a therapeutic treatment, which consisted of a PG-activated implant, previously described to exert a mild mitogenic effect to the host
Summary
Sepsis is a polyparametric condition, which back in the early ‘90s was defined as a systematic inflammatory response resulting in a variety of severe clinical symptoms [1], early in 2001 it was defined as “infection” [2] and today it is defined as life-threatening organ dysfunction caused by dysregulated response of the host to infection [3]. Due to the immunosuppressive nature of this pathology, immunostimulatory therapies, including granulocyte macrophage colony stimulating factor, interleukin 7, programmed death-1 inhibitors, intravenous immunoglobulin (IVIG) treatment enriched or not with IgM, have been envisaged as potential treatments [10,11,12,13,14] To this extend, the application of IgG and IgM in a sepsis-like murine LPSinduced endotoxemia model significantly decreased the percent of myeloid-derived suppressor cells (CD11b + Gr1 + cells), and regulatory T cells (CD25+, Foxp3 + cells), the arginase-1 activity in the spleen, while decreasing IL-6, TNF-α and CRP levels in the serum, allowing survival to all animals tested [15]
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