4-Ethylguaiacol modulates neuroinflammation and Th1/Th17 differentiation to ameliorate disease severity in experimental autoimmune encephalomyelitis

Abstract

Abstract Multiple sclerosis (MS) is a progressive autoimmune disease characterized by the accumulation of pathogenic inflammatory immune cells in the central nervous system (CNS) that subsequently causes focal inflammation, demyelination, and neuronal damage. Experimental Autoimmune Encephalomyelitis (EAE) is a well-established murine model of MS. Presently, growing evidences show that phenolic compounds exert anti-inflammatory effects by inhibiting the production of inflammatory molecules. 4-ethylguaiacol (4-EG), a phenolic compound, which was detected in foods, such as green bell peppers, corns, sesames, and coffee has been shown to possess anti-inflammatory effects through attenuating peripheral immune responses. However, whether 4-EG exerts anti-inflammatory effects on modulating the CNS inflammatory immune responses remains unexplored. In this study we assessed the therapeutic effect of 4-EG in EAE using both chronical and relapsing-remitting animal models. Our results showed that 4-EG not only ameliorated disease severity in chronic EAE but also mitigated disease progression in relapsing-remitting EAE. Further investigations revealed that 4-EG suppressed MG activation, inhibited Th1 and Th17 infiltration, and mitigated BBB disruption in the CNS of EAE. Furthermore, 4-EG suppressed Th1 and Th17 differentiation in the periphery of EAE. Finally, 4-EG induced HO-1 expression in the CNS of EAE as well as in MG and macrophages. In summary, our work demonstrates for the first time that 4-EG confers a protection against autoimmune disease EAE through modulating neuroinflammation and inhibiting Th1/Th17 differentiation, suggesting that 4-EG could be developed as a therapeutic agent for the treatment of MS/EAE.