Neutrophil elastase downmodulates native G-CSFR expression and granulocyte-macrophage colony formation
bone-marrow; cells; cyclic neutropenia; Immunology; leukocyte elastase; mobilization; myeloid-leukemia; progenitor; quantum proteolysis; severe congenital neutropenia; signal-transduction; stem cell; stimulating-factor-receptor
Background: The granulocyte colony-stimulating factor receptor (G-CSFR) plays a critical role in maintaining homeostatic levels of circulating neutrophils (PMN). The mechanisms modulating G-CSFR surface expression to prevent chronic neutrophilia are poorly understood. Here, we report that neutrophil elastase (NE) proteolytically cleaves the G-CSFR on human PMN and blocks G-CSFR-mediated granulopoiesis in vitro. Methods: Human peripheral blood PMN isolated from healthy donors were incubated with NE. Expression of the G-CSFR was analyzed by flow cytometry and western blot analyses. Detection of G-CSFR cleavage products from the culture supernatants was also performed. Human bone marrow mononuclear cells were also cultured in the presence or absence of NE to determine its effects on the proliferation of granulocyte-macrophage colony forming units (CFU-GM). Results: Treatment of PMN with NE induced a time-dependent decrease in G-CSFR expression that correlated with its degradation and the appearance of proteolytic cleavage fragments in conditioned media. Immunoblot analysis confirmed the G-CSFR was cleaved at its amino-terminus. Treatment of progenitor cells with NE prior to culture inhibited the growth of granulocyte-macrophage colony forming units. Conclusions: These findings indicate that in addition to transcriptional controls and ligand-induced internalization, direct proteolytic cleavage of the G-CSFR by NE also downregulates G-CSFR expression and inhibits G-CSFRmediated granulopoiesis in vitro. Our results suggest that NE negatively regulates granulopoiesis through a novel negative feedback loop.
Piper M G; Massullo P R; Loveland M; Druhan L J; Kindwall-Keller T L; Ai J; Copelan A; Avalos B R
Journal of Inflammation-London
2010
2010-01
Journal Article
<a href="http://doi.org/10.1186/1476-9255-7-5" target="_blank" rel="noreferrer noopener">10.1186/1476-9255-7-5</a>
Optical mapping of cryoinjured rat myocardium grafted with mesenchymal stem cells
cardiomyocytes; Myocardial infarction; therapy; Physiology; Cardiovascular System & Cardiology; in-vitro; repair; Transplantation; phenotype; regeneration; infarction; heart; stem cell; action potential; pacemakers
Costa AR, Panda NC, Yong S, Mayorga ME, Pawlowski GP, Fan K, Penn MS, Laurita KR. Optical mapping of cryoinjured rat myocardium grafted with mesenchymal stem cells. Am J Physiol Heart Circ Physiol 302: H270-H277, 2012. First published October 28, 2011; doi: 10.1152/ajpheart.00019.2011.-Mesenchymal stem cells (MSCs) have been shown to improve cardiac electrophysiology when administered in the setting of acute myocardial infarction. However, the electrophysiological phenotype of MSCs in situ is not clear. We hypothesize that MSCs delivered intramyocardially to cryoinjured myocardium can engraft, but will not actively generate, action potentials. Cryoinjury-induced scar was created on the left ventricular epicardial surface of adult rat hearts. Within 30 min, hearts were injected with saline (sham, n = 11) or bone marrow-derived MSCs (2 x 10(6)) labeled with 1,1'-dioctadecyl-3,3,3,3'-tetramethyl-indocarbocyanine percholate (DiI; n = 16). At 3 wk, optical mapping and cell isolation were used to measure optical action potentials and calcium transients, respectively. Histological analysis confirmed subepicardial scar thickness and the presence of DiI-positive cells that express connexin-43. Optical action potential amplitude within the scar at MSC-positive sites (53.8 +/- 14.3%) was larger compared with sites devoid of MSCs (35.3 +/- 14.2%, P < 0.05) and sites within the scar of shams (33.5 +/- 6.9%, P < 0.05). Evidence of simultaneous action potential upstroke, the loss of action potential activity following ablation of adjacent viable myocardium, and no rapid calcium transient response in isolated DiI + cells suggest that the electrophysiological influence of engrafted MSCs is electrotonic. MSCs can engraft when directly injected into a cryoinjury and are associated with evidence of action potential activity. However, our results suggest that this activity is not due to generation of action potentials, but rather passive influence coupled from neighboring viable myocardium.
Costa A R; Panda N C; Yong S; Mayorga M E; Pawlowski G P; Fan K K; Penn M S; Laurita K R
American Journal of Physiology-Heart and Circulatory Physiology
2012
2012-01
Journal Article or Conference Abstract Publication
<a href="http://doi.org/10.1152/ajpheart.00019.2011" target="_blank" rel="noreferrer noopener">10.1152/ajpheart.00019.2011</a>
Stem Cell Therapy for Heart Disease
acute myocardial-infarction; bone-marrow-cells; cardiac repair; cells; coronary-artery-disease; Function; General & Internal Medicine; Health Care Sciences & Services; Heart failure; intracoronary injection; ischemic-heart; left-ventricular; mononuclear-cells; myocardial infarction; paracrine; progenitor; randomized phase-1 trial; stem cell; ventricular function
Coronary artery disease is the leading cause of death in Americans. After myocardial infarction, significant ventricular damage persists despite timely reperfusion and pharmacological management. Treatment is limited, as current modalities do not cure this damage. In the past decade, stem cell therapy has emerged as a promising therapeutic solution to restore myocardial function. Clinical trials have demonstrated safety and beneficial effects in patients suffering from acute myocardial infarction, heart failure, and dilated cardiomyopathy. These benefits include improved ventricular function, increased ejection fraction, and decreased infarct size. Mechanisms of therapy are still not clearly understood. However, it is believed that paracrine factors, including stromal cell-derived factor-1, contribute significantly to stem cell benefits. The purpose of this article is to provide medical professionals with an overview on stem cell therapy for the heart and to discuss potential future directions.
Puliafico S B; Penn M S; Silver K H
Journal of General Internal Medicine
2013
2013-10
Journal Article
<a href="http://doi.org/10.1007/s11606-013-2508-z" target="_blank" rel="noreferrer noopener">10.1007/s11606-013-2508-z</a>