Shock : molecular, cellular, and systemic pathobiological aspects and therapeutic approaches : the official journal the Shock Society, the European Shock Society, the Brazilian Shock Society, the International Federation of Shock Societies
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Introduction: Hematopoiesis proceeds in a tiered pattern of differentiation, beginning with hematopoietic stem cells (HSC) and culminating in erythroid, myeloid, and lymphoid lineages. Pathologically altered lineage commitment can result in inadequate leukocyte production or dysfunctional cell lines. Drivers of emergency hematopoiesis after burn injury are inadequately defined. ⋯ Discussion: Full-thickness burn results in an emergency hematopoiesis via proportional increase of long-term HSC and short-term HSC/MPP1 subpopulations beginning in the early postinjury period. Subsequent lineage commitment displays a myeloid predominance with a shift toward myeloid progenitors with mRNA analysis corroborating this finding with associated upregulation of PU.1 and downregulation of GATA-1 and GATA-3. Further studies are needed to understand how burn-induced emergency hematopoiesis may predispose to infection by pathologic lineage selection.
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Severe burn injuries induce acute and chronic susceptibility to infections, which is largely attributed to a hyper-proinflammatory response followed by a chronic anti-inflammatory response. Concurrent inhalation injury (B + I) causes airway inflammation. Pulmonary macrophages and neutrophils are "hyperactive" with increased reactive oxygen (ROS) and nitrogen species (RONS) activity, but are unable to clear infection, causing airway damage upon activation. ⋯ BI-injured mice that received Combo-MP an hour after injury, inoculated 48 h later with Pseudomonas aeruginosa (PAO1), and sacrificed 48 h after infection displayed significantly decreased bacterial counts in the lungs and liver versus untreated B + I mice. This reduction in infection was accompanied by significantly altered lung and plasma cytokine profiles and immune reprogramming of pulmonary and splenic cells. Our findings strongly suggest that multimodal MP-based therapy holds considerable promise for reprogramming the immune response after burn injuries, particularly by mitigating the hyper-inflammatory phase and preventing subsequent susceptibility to infection.