Murine Myeloid Progenitors Attenuate Immune Dysfunction Induced by Hemorrhagic Shock

Abstract

Summary Hemorrhagic shock induces an aberrant immune response characterized by simultaneous induction of a proinflammatory state and impaired host defenses. The objective of this study was to evaluate the impact of conditionally immortalized neutrophil progenitors (NPs) on this aberrant immune response. We employed a mouse model of hemorrhagic shock, followed by the adoptive transfer of NPs and subsequent inoculation of Staphylococcus aureus to induce pneumonia. We observed that transplant of NPs decreases the proportion of host neutrophils that express programmed death ligand 1 and intercellular adhesion molecule 1 in the context of prior hemorrhage. Following hemorrhage, NP transplant decreased proinflammatory cytokines in the lungs, increased neutrophil migration into the airspaces, and enhanced bacterial clearance. Further, hemorrhagic shock improved NP engraftment in the bone marrow. These results suggest that NPs hold the potential for use as a cellular therapy in the treatment and prevention of secondary infection following hemorrhagic shock.

IL-1β primed mesenchymal stromal cells moderate hemorrhagic shock-induced organ injuries

“…We observed that HS induced an upregulation of these pro and anti-inflammatory cytokines. Similar results were recently reported in mice, showing an increase in circulating IL-6 and IL-10 cytokine levels 90 min and 24 h after HS [39]. These results are consistent with the clinical literature, including a study on a cohort of 89 adult trauma patients that revealed a leukocytosis, an elevated serum pro-and antiinflammatory cytokines, and evidence of innate cell activation, within minutes of trauma [26].…”

“…They also observed a simultaneous induction of a hyperinflammatory state. They finally demonstrated that mice transplantation of neutrophil progenitors following HS decreases the proportion of host neutrophils with a suppressive phenotype and also attenuates their "priming" [39]. Therefore, MSCp therapy decreased both activation and inhibition markers on monocytes and granulocytes and the plasmatic expression of pro and anti-inflammatory cytokines.…”

Engraftment, fate, and function of HoxB8-conditional neutrophil progenitors in the unconditioned murine host

“…Since the approach for conditionally immortalizing murine myeloid progenitors by exogenous expression of HoxB8 was initially described (Wang et al, 2006), others have shown that such progenitor cell lines can be transplanted into irradiated recipient mice and subsequently generate mature, terminally differentiated myeloid leukocytes in the in vivo environment (Gautam et al, 2013;Redecke et al, 2013;Orosz et al, 2021). Recently, we reported that a HoxB8-conditional progenitor cell line that we derived is able to produce substantial numbers of donor graft-derived neutrophils in mice that were not subjected to any conditioning of the hematopoietic niche (Cohen et al, 2021). To understand if the engraftment of HoxB8conditional progenitors in naïve, unconditioned mice was a unique feature of this particular progenitor cell line, we compared its engraftment to other lines of HoxB8-conditional myeloid progenitors using congenic CD45.1 recipient mice.…”

“…HoxB8 conditionally-immortalized progenitors. As described previously (Cohen et al, 2021), a lentivirus-based construct with a tamoxifen-inducible Hoxb8 oncogene (Salmanidis et al, 2013) (a gift from Paul Ekert, Murdoch Children's Research Institute) with either a puromycin or hygromycin resistance cassette was used to stably express HoxB8 in bone marrow hematopoietic stem and progenitor cells (HSPCs) isolated from C57BL/6J mice. HSPCs were cultured with recombinant murine stem cell factor (SCF) and interleukin-3 (IL-3) for two days, exactly as described (Wang et al, 2006), and then subjected to spin-infection (2000 RPM, 60 min, 30°C) with lentivirus in a 24-well plate.…”

“…We have previously shown that cells in the bone marrow derived from transplanted HoxB8conditional progenitors that were loaded with a cell proliferation dye exhibit a greater than 20-fold dilution of the dye within 3 days, indicating in vivo proliferation of donor progenitors prior to their differentiation (Cohen et al, 2021). Analyses of all donor-derived cells in the bone marrow at days 4 and 7 after transplant indicate that their composition shifts from being split between cKit + Ly6G low progenitors and cKit -Ly6G high neutrophils at day 4, to predominantly cKit -Ly6G high neutrophils at day 7 (Figure 3B and 3C).…”