Augmenting emergency granulopoiesis with CpG conditioned mesenchymal stromal cells in murine neutropenic sepsis

Abstract

Patients with immune deficiencies from cancers and associated treatments represent a growing population within the intensive care unit with increased risk of morbidity and mortality from sepsis. Mesenchymal stromal cells (MSCs) are an integral part of the hematopoietic niche and express toll-like receptors, making them candidate cells to sense and translate pathogenic signals into an innate immune response. In this study, we demonstrate that MSCs administered therapeutically in a murine model of radiation-associated neutropenia have dual actions to confer a survival benefit in Pseudomonas aeruginosa pneumo-sepsis that is not from improved bacterial clearance. First, MSCs augment the neutrophil response to infection, an effect that is enhanced when MSCs are preconditioned with CpG oligodeoxynucleotide, a toll-like receptor 9 agonist. Using cytometry by time of flight, we identified proliferating neutrophils (Ly6GlowKi-67+) as the main expanded cell population within the bone marrow. Further analysis revealed that CpG-MSCs expand a lineage restricted progenitor population (Lin−Sca1+C-kit+CD150−CD48+) in the bone marrow, which corresponded to a doubling in the myeloid proliferation and differentiation potential in response to infection compared with control. Despite increased neutrophils, no reduction in organ bacterial count was observed between experimental groups. However, the second effect exerted by CpG-MSCs is to attenuate organ damage, particularly in the lungs. Neutrophils obtained from irradiated mice and cocultured with CpG-MSCs had decreased neutrophil extracellular trap formation, which was associated with decreased citrullinated H3 staining in the lungs of mice given CpG-MSCs in vivo. Thus, this preclinical study provides evidence for the therapeutic potential of MSCs in neutropenic sepsis.

Single Cell RNA-seq and Mass Cytometry Reveals a Novel and a Targetable Population of Macrophages in Idiopathic Pulmonary Fibrosis

“…CyTOF analysis was performed as previously described (51). Briefly, mass cytometry data was analyzed using Cytobank online software (https://cytobank.org) to perform t-Distribution Stochastic Neighbor Embedding (tSNE) analysis(85).…”

“…The data was analyzed using Cytobank (https://cytobank.org) and as previously described by Ng. et al (51). We first manually gated for common leukocyte populations within the intact, singlet, liveCD45+ cell subset to determine the proportion of cell populations found between the three groups ( Figure 5A).…”

Polypharmacy to Mitigate Acute and Delayed Radiation Syndromes

“…Currently, several agents have demonstrated efficacy to mitigate ARS (Ng et al, 2020;REMM, 2020). However, only granulocyte colony-stimulating factor (G-CSF, Neupogen), granulocyte macrophage colony-stimulating factor (GM-CSF, Leukine) and PEGylated G-CSF (Neulasta) are approved by the U.S. Food and Drug Administration (FDA) to be used after exposure to myelosuppressive doses of radiation (USFDA, 2015a; USFDA, 2021; Amgen, 2015a;Amgen, 2015b;Sanofi-Aventis, 2018).…”

Intratracheal transplantation of trophoblast stem cells attenuates acute lung injury in mice

“…Undiluted samples (20 mL) were used for analysis by Luminex FlexMap 3D assay system per manufacturer’s instructions [ 23 ]. The levels of interleukin (IL) 6, monocyte chemoattractant protein (MCP) 1, and keratinocytes-derived chemokine (KC) were determined by standard curve analysis.…”