Indoles mitigate the development of experimental autoimmune encephalomyelitis by induction of reciprocal differentiation of regulatory T cells and Th17 cells

Abstract

Background and Purpose Dietary indole derivatives, indole‐3‐carbinol (I3C) and diindolylmethane (DIM), possess anti‐cancer properties and exhibit the characteristics of aryl hydrocarbon receptor (AhR) ligands. Because AhR activation has recently been shown to regulate T cell differentiation, we tested the hypothesis that I3C and DIM may mediate anti‐inflammatory properties by promoting regulatory T cell (T‐regs) differentiation while inhibiting Th17 cells. Experimental Approach We investigated the therapeutic efficacy of I3C and DIM against experimental autoimmune encephalomyelitis (EAE), a murine model of multiple sclerosis (MS). The efficacy was evaluated based on clinical scores of paralysis, histopathology, serum cytokines and infiltration of T cells in the CNS. We next studied the mechanism of induction of T cells against myelin oligodendrocyte glycoprotein (MOG35–55) peptide, both in vivo and in vitro, specifically investigating the differentiation of T‐regs and Th17 cells, and determined if indoles were acting through AhR. Key Results Pretreatment of EAE mice with I3C or DIM completely prevented the clinical symptoms and cellular infiltration into the CNS. Also, post‐treatment of EAE with I3C or DIM proved highly effective in curtailing the overall severity of the disease. In addition, I3C or DIM promoted the generation of T‐regs, while down‐regulating the induction of MOG‐specific Th17 cells. The regulation of FoxP3 induction and suppression of Th17 cells by indoles in vivo and in vitro were found to be AhR‐dependent. Conclusions and Implications Together, our studies demonstrate for the first time that I3C and DIM may serve as novel therapeutics to suppress neuroinflammation seen during MS through activation of AhR.

Indoles from commensal bacteria extend healthspan

“…Whereas data presented here show protective effects of E. coli K12 versus K12ΔtnaA, recent data suggest that other intestinal eubacteria, including many Bacteroides and Lactobacillus species, likewise use TnaA to produce protective indole derivatives, including ICA and indole-3-carbinol (I3C)) (16,(48)(49)(50). Responsiveness to particular indoles may differ and be tuned to the precise complement of indoles produced by the microbiota.…”

3,3'-Diindolylmethane Ameliorates Staphylococcal Enterotoxin B-Induced Acute Lung Injury through Alterations in the Expression of MicroRNA that Target Apoptosis and Cell-Cycle Arrest in Activated T Cells

“…Splenocytes were isolated from naïve C57BL/6 mice and cultured with SEB (1 mg/ml) in the absence or presence of vehicle or DIM (10-50 mM) for 6, 12, 18, and 24 hours. In vitro concentrations of DIM were based on previous work from our laboratory and well within attainable concentrations found after oral administration of DIM in mice (Anderton et al, 2004;Rouse et al, 2013;Busbee et al, 2014). Cells were harvested and fixed with 2% paraformaldehyde for 1 hour at 4°C.…”

“…Indigoid compounds have been extensively studied for their anti-cancer properties (Ahmad et al, 2010;Banerjee et al, 2011). The immunosuppressive role for DIM has been studied in a number of inflammatory diseases, including experimental arthritis (Dong et al, 2010), colitis (Huang et al, 2013), and autoimmune encephalomyelitis (Rouse et al, 2013).…”

3,3′-Diindolylmethane Ameliorates Experimental Autoimmune Encephalomyelitis by Promoting Cell Cycle Arrest and Apoptosis in Activated T Cells through MicroRNA Signaling Pathways

“…EAE was induced in female C57BL/6 mice (6-8 weeks old) via subcutaneous immunization with 100 ml of 150 mg MOG 35-55 peptide emulsified in complete Freund's adjuvant (Difco, Detriot, MI) containing 4 mg/ml killed Mycobacterium tuberculosis (strain H37Ra; Difco), as described by us previously (Singh et al, 2007;Rouse et al, 2013). Following immunization, 200 ng of pertussis toxin (List Biological Laboratories, Campbell, CA) was injected intraperitoneally into mice on day 0, followed by a 400-ng pertussis toxin intraperitoneal injection on day 2.…”