Application of multianalyte microphysiometry to characterize macrophage metabolic responses to oxidized LDL and effects of an apoA-1 mimetic

Abstract

Although the interaction of macrophages with oxidized low density liopoprotein (oxLDL) is critical to the pathogenesis of atherosclerosis, relatively little is known about their metabolic response to oxLDL. Our development of the multianalyte microphysiometer (MAMP) allows for simultaneous measurement of extracellular metabolic substrates and products in real-time. Here, we use the MAMP to study changes in the metabolic rates of RAW-264.7 cells undergoing respiratory burst in response to oxLDL. These studies indicate that short duration exposure of macrophages to oxLDL results in time-dependent increases in glucose and oxygen consumption and in lactate production and extracellular acidification rate. Since apolipoprotein A-I (apoA-I) and apoA-I mimetics prevent experimental atherosclerosis, we hypothesized that the metabolic response of the macrophage during respiratory burst can be modulated by apoA-I mimetics. We tested this hypothesis by examining the effects of the apoA-I peptide mimetic, L-4F, alone and complexed with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) on the macrophage metabolic response to oxLDL. L-4F and the DMPC/L-4F complexes attenuated the macrophage respiratory burst in response to oxLDL. The MAMP provides a novel approach for studying macrophage ligand-receptor interactions and cellular metabolism and our results provide new insights into the metabolic effects of oxLDL and mechanism of action of apoA-I mimetics.

IL4 receptor α mediates enhanced glucose and glutamine metabolism to support breast cancer growth

“…This indicates that IL4/IL4Rα signaling may also influence the translocation of GLUT1 to the membrane for more immediate increases in glucose uptake and metabolism in addition to the later transcriptional upregulation of GLUT1 for maintaining enhanced glucose metabolism long-term. This concept is supported by additional experiments demonstrating increased glucose uptake by 2-NBDG uptake assay, and increased lactate production detected by multianalyte microphysiometry [30,31] (data not shown), after short-term IL4 exposure. However, more detailed assessment of GLUT1 translocation is required to substantiate this idea.…”

“…Glucose uptake reported as mean 2-NBDG fluorescence was significantly increased in cells treated with IL4 (Figure 2A,B). Furthermore, using a sensitive multianalyte microphysiometer (MAMP) [30,31], we found that IL4 stimulated lactate production by ~8.5% from 4T1 cells within minutes of exposure (data not shown). These data confirmed that IL4 enhances short-term glucose uptake and possibly its metabolism in mammary cancer cells.…”

Apolipoprotein A-I mimetics

“…Using a multianalyte microphysiometer, it was demonstrated that L-4F complexed or not complexed with 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) attenuated the macrophage respiratory burst in response to oxidized LDL [10*]. …”

A microfluidic optical platform for real-time monitoring of pH and oxygen in microfluidic bioreactors and organ-on-chip devices

“…25 Microfluidic detection methods are highly suited for integration with organ-on-chip devices due to their potential for the analysis of low-volume liquids and high degree of automation. 29 A variety of microfluidic optical and electrochemical techniques have been developed to measure oxygen 22,[30][31][32][33][34][35][36][37][38] and pH 31,34,37,[39][40][41][42][43][44] for cell-based studies. Moreover, in some instances, the optical methods are preferred over electrical methods since they do not require electrical connections and electrodes which may be prone to biofouling and corrosion.…”