Kaposi Sarcoma Herpes Virus (KSHV) infection inhibits macrophage formation and survival by counteracting Macrophage Colony-Stimulating Factor (M-CSF)-induced increase of Reactive Oxygen Species (ROS), c-Jun N-terminal kinase (JNK) phosphorylation and autophagy

Microglia activation and proliferation are hallmarks of many neurodegenerative disorders and may contribute to disease pathogenesis. Neurons actively regulate microglia survival and function, in part by secreting the microglia mitogen interleukin (IL)-34. Both IL-34 and colony stimulating factor (CSF)-1 bind colony stimulating factor receptor (CSFR)1 expressed on microglia. Systemic treatment with central nervous system (CNS) penetrant, CSFR1 antagonists, results in microglia death in a dose dependent matter, while others, such as GW2580, suppress activation during disease states without altering viability. However, it is not known how treatment with non-penetrant CSF1R antagonists, such as GW2580, affect the normal physiology of microglia. To determine how GW2580 affects microglia function, C57BL/6J mice were orally gavaged with vehicle or GW2580 (80mg/kg/d) for 8 days. Body weights and burrowing behavior were measured throughout the experiment. The effects of GW2580 on circulating leukocyte populations, brain microglia morphology, and the transcriptome of magnetically isolated adult brain microglia were determined. Body weights, burrowing behavior, and circulating leukocytes were not affected by treatment. Analysis of Iba-1 stained brain microglia indicated that GW2580 treatment altered morphology, but not cell number. Analysis of RNA-sequencing data indicated that genes related to reactive oxygen species (ROS) regulation and survival were suppressed by treatment. Treatment of primary microglia cultures with GW2580 resulted in a dose-dependent reduction in viability only when the cells were concurrently treated with LPS, an inducer of ROS. Pre-treatment with the ROS inhibitor, YCG063, blocked treatment induced reductions in viability. Finally, GW2580 sensitized microglia to hydrogen peroxide induced cell death. Together, these data suggest that partial CSF1R antagonism may render microglia more susceptible to reactive oxygen and nitrogen species.

Download Full-text

Reactive Oxygen Species Alter Gene Expression in Podocytes: Induction of Granulocyte Macrophage-Colony-Stimulating Factor

Journal of the American Society of Nephrology ◽

10.1681/asn.v13186 ◽

2002 ◽

Vol 13 (1) ◽

pp. 86-95

Author(s):

Stefan Greiber ◽

Barbara Müller ◽

Petra Daemisch ◽

Hermann Pavenstädt

Keyword(s):

Gene Expression ◽

Reactive Oxygen ◽

Differentially Expressed ◽

Northern Analysis ◽

Colony Stimulating Factor ◽

Gm Csf ◽

Macrophage Colony Stimulating Factor ◽

Macrophage Colony ◽

Stimulating Factor ◽

Csf Production

ABSTRACT. It has been suggested that reactive oxygen radicals (ROS) play a crucial role in the pathogenesis of proteinuria and podocyte injury. It was investigated whether changes in gene expression might account for ROS-induced podocyte dysfunction. Differentiated podocytes were incubated with control media or with exogenous ROS from the xanthine/xanthine-oxidase reaction for 4 h. A PCR-based suppressive subtractive hybridization assay was applied to isolate and clone mRNAs that were differentially expressed by exogenous ROS. One differentially expressed clone was identified as the proinflammatory cytokine granulocyte macrophage-colony-stimulating factor (GM-CSF). Regulation of GM-CSF in podocytes was further studied by Northern analysis and enzyme-linked immunosorbent assay. Exogenous ROS caused a concentration-dependent, >10-fold induction of GM-CSF mRNA after 4 h. A >50-fold increase in GM-CSF protein release in podocytes that had been stimulated with ROS could be detected. Induction of GM-CSF protein was inhibited by actinomycin D, which indicated that increased mRNA transcription was involved. The ROS scavengers dimethyl-thio-urea and pyrrolidone-dithio-carbamate strongly inhibited increased GM-CSF production induced by ROS. GM-CSF release was also induced when internal ROS production was triggered with NADH, whereas H2O2 had only a small effect. GM-CSF release by podocytes was also stimulated by lipopolysaccharide (LPS), interleukin-1 (IL-1), and phorbolester (PMA). Dimethyl-thio-urea significantly inhibited the LPS-, IL-1-, and PMA-induced GM-CSF production. Activation of the transcription factor nuclear factor-κB (NF-κB) but not activator protein-1 was involved in the upregulation of ROS-induced GM-CSF production. The data indicate that GM-CSF is differentially expressed by ROS in podocytes. ROS also partially mediate the effects of PMA and IL-1 on podocyte GM-CSF production. Because GM-CSF can enhance glomerular inflammation and induces mesangial proliferation, these data might provide further insight into the mechanisms of ROS-induced glomerular injury.

Download Full-text

Abstract 3648: A Dual Role for Granulocyte-Colony Stimulating Factor in Promotion of Coronary Collateral Growth and Production of Cardiomyocyte Reactive Oxygen Species

Circulation ◽

10.1161/circ.118.suppl_18.s_458-a ◽

2008 ◽

Vol 118 (suppl_18) ◽

Author(s):

Ana C Carrão ◽

Wiliam M Chilian ◽

June Yun ◽

Chris Kolz ◽

Ivo Buschmann

Keyword(s):

Reactive Oxygen Species ◽

Cardiac Myocytes ◽

Reactive Oxygen ◽

Oxygen Species ◽

Granulocyte Colony Stimulating Factor ◽

Colony Stimulating Factor ◽

Coronary Collateral ◽

Collateral Growth ◽

Coronary Collateral Growth ◽

Stimulating Factor

Granulocyte colony-stimulating factor (G-CSF) is a hematopoietic cytokine that promotes proliferation and differentiation of neutrophil progenitors. Because G-CSF ameliorates myocar-dial ischemic injury, we projected this effect would also translate into stimulating myocardial adaptations to ischemia. Accordingly, we hypothesized that G-CSF stimulates coronary collateral growth (CCG) in a rat model of repetitive episodic ischemia (RI): 40 sec LAD occlusion every 20 min for 2h20min, 3 times/day for 5 days. CCG was deduced from collateral-dependent flow (flow to LAD region during occlusion [neutron activated microspheres]) and expressed as the increase in the ratio between collateral-dependent and normal zone flows from the initial measurement to that after 5 days of RI. Following RI, G-CSF (100 microg/Kg/day) increased CCG (P<0.01) (0.47 +− 0.15) versus vehicle (0.14 +− 0.06). Surprisingly, G-CSF treatment without RI increased CCG (0.57 +− 0.18, P<0.01 vs vehicle) equal to G-CSF +RI. Because redox signaling is critical for CCG and neutrophils are a rich source of NADPH oxidase and reactive oxygen species (ROS), we hypothesized that G-CSF stimulates production of ROS. We evaluated ROS by dihydroethidine (DHE) fluorescence (LV injection, 60 microg/kg, during two episodes of ischemia). DHE fluorescence was double in G-CSF+RI vs vehicle+RI (P<0.01), and even higher in G-CSF without RI (P<0.01). Interestingly, the DHE signal did not co-localize with myeloperoxidase (immunostaining, neutrophil marker) but appeared in cardiac myocytes. To unequivocally determine if G-CSF stimulates ROS production in cardiac myocytes, we studied isolated cardiac myocytes and found the cytokine stimulates ROS. In addition to affecting neutrophils, G-CSF directly targets cardiac myocytes to produce ROS. In conclusion, G-CSF stimulates production of ROS by cardiac myocytes, which likely plays a pivotal role in adaptations of the heart to ischemia including growth of the coronary collateral circulation.

Download Full-text