Exogenous Glutamine in Respiratory Diseases: Myth or Reality?

Abstract

Several respiratory diseases feature increased inflammatory response and catabolic activity, which are associated with glutamine depletion; thus, the benefits of exogenous glutamine administration have been evaluated in clinical trials and models of different respiratory diseases. Recent reviews and meta-analyses have focused on the effects and mechanisms of action of glutamine in a general population of critical care patients or in different models of injury. However, little information is available about the role of glutamine in respiratory diseases. The aim of the present review is to discuss the evidence of glutamine depletion in cystic fibrosis (CF), asthma, chronic obstructive pulmonary disease (COPD), acute respiratory distress syndrome (ARDS), and lung cancer, as well as the results of exogenous glutamine administration in experimental and clinical studies. Exogenous glutamine administration might be beneficial in ARDS, asthma, and during lung cancer treatment, thus representing a potential therapeutic tool in these conditions. Further experimental and large randomized clinical trials focusing on the development and progression of respiratory diseases are necessary to elucidate the effects and possible therapeutic role of glutamine in this setting.

<p>Differences in plasma amino acid levels in patients with and without bacterial infection during the early stage of acute exacerbation of COPD</p>

“…These findings suggest that there is a decrease in both plasma arginine levels and the capacity to synthesize NO in patients with AECOPD, regardless of whether or not bacterial infection is present. A review of the relationship between glutamine and various respiratory diseases highlights the important role of the lungs in glutamine homeostasis, which is therefore altered in various pulmonary diseases 32…”

A metabolic handbook for the COVID-19 pandemic

“…However, in other models with various methods of lung injury induction and routes of glutamine administration, glutamine has been found to be protective against ARDS. The differences in effects on disease pathogenesis are likely to be explained by the differences in the route of glutamine administration, timing and specific insult triggering ARDS 70 (Fig. 6).…”

An Updated Overview of Metabolomic Profile Changes in Chronic Obstructive Pulmonary Disease

“…Glutamine and glutamate also have critical regulatory effects on antioxidative stress and biosynthesis under metabolic dysfunction conditions, such as decreasing glutathione level and negatively regulating nitrogen balance [65]. Glutamine mainly comes from the metabolism of skeletal muscle; however, the lung also has potential to release glutamine under stress conditions, indicating an increased utilization of glutamine in lung tissue [66]. In comparison, glutamine levels increase in COPD, which may be associated with abnormal skeletal muscle protein metabolism and oxidative stress.…”