cells Review Carbohydrate and Amino Acid Metabolism as Hallmarks for Innate Immune Cell Activation and Function 1, 1, 1,2, Haoxin Zhao y, Lydia N. Raines y and Stanley Ching-Cheng Huang * 1 Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA;
[email protected] (H.Z.);
[email protected] (L.N.R.) 2 Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA * Correspondence:
[email protected]; Tel.: +1-216-368-3909 These authors have contributed equally. y Received: 10 February 2020; Accepted: 26 February 2020; Published: 27 February 2020 Abstract: Immune activation is now understood to be fundamentally linked to intrinsic and/or extrinsic metabolic processes which are essential for immune cells to survive, proliferate, and perform their effector functions. Moreover, disruption or dysregulation of these pathways can result in detrimental outcomes and underly a number of pathologies in both communicable and non-communicable diseases. In this review, we discuss how the metabolism of carbohydrates and amino acids in particular can modulate innate immunity and how perturbations in these pathways can result in failure of these immune cells to properly function or induce unfavorable phenotypes. Keywords: innate immunity; carbohydrates; amino acids; immunometabolism 1. Carbohydrate and Amino Acid Metabolism The field of immunometabolism has grown significantly over the past several decades, perhaps driven by the realization that cellular metabolism is fundamental to the activation and effector function of all cells within the body. While early links between immunity and metabolism were uncovered in the late 1900s, it was not until the early 2000s when it was observed that macrophages within the adipose tissue of obese mice exhibited an upregulation of inflammatory gene expression that this association was fully appreciated [1,2].