Coping With Stress: The Mitokine GDF-15 as a Biomarker of COVID-19 Severity.

Growth differentiation factor 15 (GDF-15) is a transforming growth factor (TGF)-ß superfamily cytokine that plays a central role in metabolism regulation. Produced in response to mitochondrial stress, tissue damage or hypoxia, this cytokine has emerged as one of the strongest predictors of disease severity during inflammatory conditions, cancers and infections. Reports suggest that GDF-15 plays a tissue protective role via sympathetic and metabolic adaptation in the context of mitochondrial damage, although the exact mechanisms involved remain uncertain. In this review, we discuss the emergence of GDF-15 as a distinctive marker of viral infection severity, especially in the context of COVID-19. We will critically review the role of GDF-15 as an inflammation-induced mediator of disease tolerance, through metabolic and immune reprogramming. Finally, we discuss potential mechanisms of GDF-15 elevation during COVID-19 cytokine storm and its limitations. Altogether, this cytokine seems to be involved in disease tolerance to viral infections including SARS-CoV-2, paving the way for novel therapeutic interventions.

GDF15/GFRAL Pathway as a Metabolic Signature for Cachexia in Patients with Cancer.

Cachexia is a metabolic mutiny that directly reduces life expectancy in chronic conditions such as cancer. The underlying mechanisms associated with cachexia involve inflammation, metabolism, and anorexia. Therefore, the need to identify cachexia biomarkers is warranted to better understand catabolism change and assess various therapeutic interventions. Among inflammatory proteins, growth differentiation factor-15 (GDF15), an atypical transforming growth factor-beta (TGF-ß) superfamily member, emerges as a stress-related hormone. In inflammatory conditions, cardiovascular diseases, and cancer, GDF15 is a biomarker for disease outcome. GDF15 is also implicated in energy homeostasis, body weight regulation, and plays a distinct role in cachexia. The recent discovery of its receptor, glial cell line-derived neurotrophic factor (GDNF) family receptor α-like (GFRAL), sheds light on its metabolic function. Herein, we critically review the mechanisms involving GDF15 in cancer cachexia and discuss therapeutic interventions to improve outcomes in people living with cancer.