Interleukin-4 (IL-4), but not IL-10, regulates the synthesis of IL-6, IL-8 and leukemia inhibitory factor by human bone marrow stromal cells

AbstractLeukemia inhibitory factor (LIF), interleukin 6 (IL-6) and IL-8 are important regulators of inflammation and hematopoiesis. Human bone marrow stromal cells regulate marrow hematopoiesis by secreting cytokines. By using reverse-transcriptase polymerase chain reaction (RT-PCR), we demonstrate that human bone marrow stromal cells constitutively express LIF, IL-6 and IL-8 transcripts. By using specific ELISAs, we found that their spontaneous productions of LIF, IL-6 and IL-8 are elevated in response to serum and after stimulation with the pro-inflammatory cytokines IL-1α and TNF-α. The anti-inflammatory cytokine IL-4 reduces their serum- and cytokine-induced LIF secretion. By contrast, IL-4 stimulates their serum- and IL-1α-induced IL-6 synthesis. IL-4 has no effect on the serum-induced IL-8 synthesis by marrow stromal cells, but stimulates their cytokine-induced IL-8 production. The anti-inflammatory cytokine IL-10 has no effect on the serum- and cytokine-induced LIF, IL-6 and IL-8 synthesis by bone marrow stromal cells. RT-PCR experiments reveal the presence of IL-4 receptor α-chain mRNA and IL-10 receptor mRNA in cultured bone marrow stromal cells. The differential regulation by IL-4 of two related cytokines, such as LIF and IL-6, and the enhanced effect of this ‘anti-inflammatory’ cytokine on IL-6 and IL-8 synthesis highlight the tightly controlled regulation and the complexity of the cytokine production within the human bone marrow

Phosphomimetic Modulation of eNOS Improves Myocardial Reperfusion and Mimics Cardiac Postconditioning in Mice

Objective: Myocardial infarction resulting from ischemia-reperfusion injury can be reduced by cardiac postconditioning, in which blood flow is restored intermittently prior to full reperfusion. Although key molecular mechanisms and prosurvival pathways involved in postconditioning have been identified, a direct role for eNOS-derived NO in improving regional myocardial perfusion has not been shown. The objective of this study is to measure, with high temporal and spatial resolution, regional myocardial perfusion during ischemia-reperfusion and postconditioning, in order to determine the contribution of regional blood flow effects of NO to infarct size and protection. Methods and Results: We used myocardial contrast echocardiography to measure regional myocardial blood flow in mice over time. Reperfusion after myocardial ischemia-reperfusion injury is improved by postconditioning, as well as by phosphomimetic eNOS modulation. Knock-in mice expressing a phosphomimetic S1176D form of eNOS showed improved myocardial reperfusion and significantly reduced infarct size. eNOS knock-out mice failed to show cardioprotection from postconditioning. The size of the no-reflow zone following ischemia-reperfusion is substantially reduced by postconditioning and by the phosphomimetic eNOS mutation. Conclusions and Significance: Using myocardial contrast echocardiography, we show that temporal dynamics of regional myocardial perfusion restoration contribute to reduced infarct size after postconditioning. eNOS has direct effects on myocardial blood flow following ischemia-reperfusion, with reduction in the size of the no-reflow zone. These results have important implications for ongoing clinical trials on cardioprotection, because the degree of protective benefit may be significantly influenced by the regional hemodynamic effects of eNOS-derived NO.American Heart Association (Predoctoral Fellowship)National Institutes of Health (U.S.) (R01 NS33335)National Institutes of Health (U.S.) (R01 HL57818

Brown adipose tissue blood flow and mass in obesity: a contrast ultrasound study in mice

Background: When activated by the sympathetic nervous system, brown adipose tissue (BAT) increases energy expenditure to produce heat. Augmenting BAT mass or increasing BAT activation could potentially be used to decrease obesity. Noninvasive methods to detect and monitor BAT mass are needed. Contrast ultrasound can estimate BAT blood flow and is able to measure the perfused volume of an organ and thus its mass. The objective of this study was to evaluate whether contrast ultrasound could characterize BAT mass in two mouse models of obesity: wild-type mice fed a high-fat diet and mutant db/db mice. Methods: Contrast ultrasound of BAT (Definity 2 mu L/min; 14-MHz linear probe) was performed before and after stimulation of BAT with norepinephrine (NE). BAT replenishment curves were obtained, and blood flow was estimated by the product of the curve's plateau and slope. Additionally, consecutive two-dimensional images of perfused BAT were acquired at 1-mmintervals after stimulation with NE and used to assess BAT volume and mass. Results: BAT blood flow increased after NE infusion in all mice studied. Blood flow response to NE was similar in wild-type mice fed either a low-fat diet or a high-fat diet. BAT blood flow was lower in db/db mice than in wild-type mice (P = .02). Contrast ultrasound-derived BAT mass was correlated with BAT mass obtained at necropsy (R-2 = 0.83, P < .001). BAT mass was higher in mice fed a high-fat diet than in those fed a low-fat diet. Conclusions: Contrast ultrasound can be used to estimate BAT mass in mice when BAT vascularization is not significantly impaired. This noninvasive technique may potentially allow the serial evaluation of therapies designed to augment BAT mass