Metabolism and Autoimmune Responses: The microRNA Connection

Abstract

Distinct metabolic pathways are known to regulate growth, differentiation, survival, and activation of immune cells by providing energy and specific biosynthetic precursors. Compelling experimental evidence demonstrates that effector T cell functions are coupled with profound changes in cellular metabolism. Importantly, the effector T cell-dependent "anti-self" response characterizing the autoimmune diseases is accompanied by significant metabolic alterations. MicroRNAs (miRNAs), evolutionary conserved small non-coding RNA molecules that affect gene expression by binding to target messenger RNAs, are now known to regulate multiple functions of effector T cells, including the strength of their activation, thus contributing to immune homeostasis. In this review, we will examine the most recent studies that describe miRNA direct involvement in the metabolic reprogramming that marks effector T cell functions. In particular, we will focus on the work showing a connection between miRNA regulatory function and the molecular network dysregulation that leads to metabolic pathway derangement in autoimmunity. Finally, we will also speculate on the possibility that the interplay between miRNAs and metabolism in T cells may help identify novel miRNA-based therapeutic strategies to treat effector T cell immunometabolic alterations in pathological conditions such as autoimmunity and chronic inflammation.

Keywords: T cells; autoimmune diseases; immunometabolism; metabolic regulation; miRNAs.

Figure 1

miRNAs orchestrate T cell metabolic reprogramming. Schematic representation of the main metabolic programs controlled by miRNAs in T cells: Glycolysis, pentose phosphate pathway (PPP), fatty acid oxidation (FAO), tricarboxylic acid (TCA) cycle, glutaminolysis, and oxidative phosphorylation (OXPHOS).

Figure 2

miRNA biogenesis and function. Schematic representation of miRNA biogenesis pathway and biological function. Di George syndrome Critical Region 8 (DGCR8), exportin-5 (XPO5), GTP-binding nuclear protein Ran (RanGTP), trans-activator RNA binding protein (TRBP), Argonaute protein 2 (Ago2), and RNA-induced silencing complex (RISC).