Impaired interleukin-8- and GROα-induced phosphorylation of extracellular signal-regulated kinase result in decreased migration of neutrophils from patients with myelodysplasia

Abstract

Patients with myelodysplasia suffer from recurrent bacterial infections as a result of differentiation defects of the myeloid lineage and a disturbed functioning of neutrophilic granulocytes. Important physiological activators of neutrophils are the cytokines interleukin-8/CXC chemokine ligand 8 (IL-8/CXCL8), which activates CXC chemokine receptor 1 and 2 (CXCR1 and CXCR2), and growth-related oncogene (GROalpha)/CXCL1, which stimulates only CXCR2. In this study, we show that migration toward IL-8/GROalpha gradients is decreased in myelodysplastic syndrome (MDS) neutrophils compared with healthy donors. We investigated the signal transduction pathways involved in IL-8/GROalpha-induced migration and showed that specific inhibitors for extracellular signal-regulated kinase (ERK)1/2 and phosphatidylinositol-3 kinase (PI-3K) abrogated neutrophil migration toward IL-8/GROalpha. In accordance with these results, we subsequently showed that IL-8/GROalpha-stimulated activation of ERK1/2 was substantially diminished in MDS neutrophils. Activation of the PI-3K downstream target protein kinase B/Akt was disturbed in MDS neutrophils when cells were activated with IL-8 but normal upon GROalpha stimulation. IL-8 stimulation resulted in higher migratory behavior and ERK1/2 activation than GROalpha stimulation, suggesting a greater importance of CXCR1. We then investigated IL-8-induced activation of the small GTPase Rac implicated in ERK1/2-dependent migration and found that it was less efficient in neutrophils from MDS patients compared with healthy donors. In contrast, IL-8 triggered a normal activation of the GTPases Ras and Ral, indicating that the observed defects were not a result of a general disturbance in CXCR1/2 signaling. In conclusion, our results demonstrate a disturbed CXCR1- and CXCR2-induced neutrophil chemotaxis in MDS patients, which might be the consequence of decreased Rac-ERK1/2 and PI-3K activation within these cells.

Short-Term Heat Exposure Inhibits Inflammation by Abrogating Recruitment of and Nuclear Factor-κB Activation in Neutrophils Exposed to Chemotactic Cytokines

“…ERK inhibitors blocked CCL3-induced migration of GM-CSF-primed neutrophils in a study done by Ottonello and colleagues, 49 but Coffer and colleagues 48 found PI3-K dependence in GM-CSF-induced migration whereas inhibition of ERK with PD98059 had no effect. Fuhler and colleagues 47 showed that specific inhibitors for ERK1/2 abrogated neutrophil migration toward IL-8, similar to our own observation. However, in our experiments PI3-K/Akt, but not ERK activation was inhibited by prior heat.…”

“…Other investigators also reported the fact that PI3-K/Akt controls neutrophil migration in response to IL-8 or GM-CSF. 2,47,48 However, whether or not ERK is important for migration is still a matter of controversy. ERK inhibitors blocked CCL3-induced migration of GM-CSF-primed neutrophils in a study done by Ottonello and colleagues, 49 but Coffer and colleagues 48 found PI3-K dependence in GM-CSF-induced migration whereas inhibition of ERK with PD98059 had no effect.…”

Expression of CXCL1 in human endothelial cells induces angiogenesis through the CXCR2 receptor and the ERK1/2 and EGF pathways

“…31 We used the PathScan Intracellular Signaling Array Kit to monitor the expression of 18 signaling molecules that are phosphorylated in response to signal-transduction pathway activation. Treatment of both HUVECs and HDMECs with recombinant CXCL1 resulted in an increase in ERK1/2 signaling, and interference of CXCL1 function with neutralizing antibodies caused a corresponding decrease in phosphorylation of ERK1/2 (Figure 3a).…”

Cases of psoriasis improved by lowering homocysteine using 4-7 mg folic acid, vitamins B6 and B12 previously worsened using 1-2 mg daily folic acid, B6 and B12 folic acid

“…Hcy also increases intracellular H2O2 production by neutrophils and neutrophil migration [2,3]. Hcy reduces endothelial nitric oxide synthase causing endothelial dysfunction [4,5].…”