Glycolysis controls the induction of human regulatory T cells by modulating the expression of FOXP3 exon 2 splicing variants

Abstract

Human regulatory T cells (Treg cells) that develop from conventional T cells (Tconv cells) following suboptimal stimulation via the T cell antigen receptor (TCR) (induced Treg cells (iTreg cells)) express the transcription factor Foxp3, are suppressive, and display an active proliferative and metabolic state. Here we found that the induction and suppressive function of iTreg cells tightly depended on glycolysis, which controlled Foxp3 splicing variants containing exon 2 (Foxp3-E2) through the glycolytic enzyme enolase-1. The Foxp3-E2–related suppressive activity of iTreg cells was altered in human autoimmune diseases, including multiple sclerosis and type 1 diabetes, and was associated with impaired glycolysis and signaling via interleukin 2. This link between glycolysis and Foxp3-E2 variants via enolase-1 shows a previously unknown mechanism for controlling the induction and function of Treg cells in health and in autoimmunity.

Cutting Edge: Increased Autoimmunity Risk in Glycogen Storage Disease Type 1b Is Associated with a Reduced Engagement of Glycolysis in T Cells and an Impaired Regulatory T Cell Function

“…Total cell lysates were obtained, and total protein was subjected to SDS-PAGE, as described (16). The following Abs were used: anti-Erk1/2 (H72; Santa Cruz Biotechnology), Ab to FOXP3 all (PCH101; eBioscience), and Ab to FOXP3-PE (150D/E4; eBioscience).…”

“…PBMCs from GSD-1a patients, GSD-1b patients, and control subjects were cultured in medium or stimulated with anti-CD3 (OKT3) (4 3 10 5 cells per well in 96-well culture plate) in 200 ml of RPMI 1640 medium supplemented with 5% autologous subject serum or 5% heterologous commercial pooled AB human serum (EuroClone) and incubated at 37˚C for 12 h. ECAR and OCR measurements were performed as previously described (16).…”

“…It has been shown that different cellular metabolic pathways are able to induce effector or regulatory responses, because distinct metabolic programs are required for the commitment of effector or Treg responses (13). In this context, although Tregs generated in vitro in the presence of TGF-b were shown to rely mainly on lipid oxidation (14), recent reports have also shown a major role for glycolysis in the induction and suppressive function of human and mouse Tregs (15,16), given the capacity of the glycolytic enzyme enolase-1 to control the expression of specific FOXP3 splicing variants in human Tregs (16). Interestingly, in human autoimmunity (i.e., multiple sclerosis and type 1 diabetes), an impaired engagement of glycolysis upon suboptimal TCR stimulation of CD4 + CD25 2 conventional T cells (Tconvs) has been observed, and this is associated with a reduced suppressive function of Tregs (16).…”

“…In this context, although Tregs generated in vitro in the presence of TGF-b were shown to rely mainly on lipid oxidation (14), recent reports have also shown a major role for glycolysis in the induction and suppressive function of human and mouse Tregs (15,16), given the capacity of the glycolytic enzyme enolase-1 to control the expression of specific FOXP3 splicing variants in human Tregs (16). Interestingly, in human autoimmunity (i.e., multiple sclerosis and type 1 diabetes), an impaired engagement of glycolysis upon suboptimal TCR stimulation of CD4 + CD25 2 conventional T cells (Tconvs) has been observed, and this is associated with a reduced suppressive function of Tregs (16). These data also suggest that glycolysis plays a key role in Treg induction and function and that its impairment leads to an unbalanced immune response, resulting in loss of self-immune tolerance (16).…”

“…Interestingly, in human autoimmunity (i.e., multiple sclerosis and type 1 diabetes), an impaired engagement of glycolysis upon suboptimal TCR stimulation of CD4 + CD25 2 conventional T cells (Tconvs) has been observed, and this is associated with a reduced suppressive function of Tregs (16). These data also suggest that glycolysis plays a key role in Treg induction and function and that its impairment leads to an unbalanced immune response, resulting in loss of self-immune tolerance (16). Building on the evidence that a strong relationship among glucose metabolism, FOXP3 expression, and regulatory function exists in human immune cells, we aimed at investigating the molecular mechanisms linking G6PT mutations and reduced glucose utilization with loss of self-immune tolerance and autoimmunity in GSD-1b patients.…”