Reactive Species from Two-Signal Activated Macrophages Interfere with Their Oxygen Consumption Measurements

Area of Science:

• Immunology
• Cellular Metabolism
• Biochemistry

Background:

• Macrophage metabolic reprogramming is key in immunotherapeutics.
• Understanding specific metabolic drivers of immune responses is critical.
• Nitric oxide (NO) plays a significant role in activated macrophages.

Purpose of the Study:

• To investigate the impact of excessive nitric oxide (NO) secretion on cellular oxygen consumption measurements in activated macrophages.
• To elucidate the mechanisms by which NO interferes with metabolic analysis.
• To provide insights for accurate metabolic characterization of cells producing reactive species.

Main Methods:

• Metabolic analysis of two-signal activated macrophages [M(2-signals)] using a seahorse metabolic analyzer.
• Assessment of oxygen consumption rates (OCR) in the presence and absence of cells.
• Evaluation of reactive species-donor effects on OCR.
• Investigation of NO production inhibition and external NO addition on macrophage respiration.

Main Results:

• M(2-signals) macrophages exhibited unresponsive respiration to mitochondrial stress.
• Excessive NO secretion by M(2-signals) macrophages interfered with oxygen consumption measurements.
• NO consumed ambient oxygen and contributed to reactive oxygen species formation.
• Inhibition of NO production partially restored macrophage respiration, while NO addition decreased OCR.

Conclusions:

• Nitric oxide (NO) significantly interferes with oxygen consumption rate measurements in activated macrophages.
• Accurate metabolic characterization requires accounting for NO's impact on oxygen levels.
• These findings are vital for reliable immunotherapeutic research involving reactive species-producing cells.