Celastrol suppresses experimental autoimmune encephalomyelitis via MAPK/SGK1-regulated mediators of autoimmune pathology
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Objective and design
Multiple sclerosis (MS) is a debilitating autoimmune disease involving immune dysregulation of the pathogenic T helper 17 (Th17) versus protective T regulatory (Treg) cell subsets, besides other cellular aberrations. Studies on the mechanisms underlying these changes have unraveled the involvement of mitogen-activated protein kinase (MAPK) pathway in the disease process. We describe here a gene expression- and bioinformatics-based study showing that celastrol, a natural triterpenoid, acting via MAPK pathway regulates the downstream genes encoding serum/glucocorticoid regulated kinase 1 (SGK1), which plays a vital role in Th17/Treg differentiation, and brain-derived neurotrophic factor (BDNF), which is a neurotrophic factor, thereby offering protection against experimental autoimmune encephalomyelitis (EAE) in mice.
We first tested the gene expression profile of splenocytes of EAE mice in response to the disease-related antigen, myelin oligodendrocyte glycoprotein (MOG), and then examined the effect of celastrol on that profile.
Interestingly, celastrol reversed the expression of many MOG-induced genes involved in inflammation and immune pathology. The MAPK pathway involving p38MAPK and ERK was identified as one of the mediators of celastrol action. It involved suppression of SGK1 but upregulation of BDNF, which then contributed to protection against EAE.
Our results not only provide novel insights into disease pathogenesis, but also offer promising therapeutic targets for MS.
KeywordsCelastrol Autoimmune diseases EAE Th17/Treg balance P38 MAPK SGK1 BDNF Multiple sclerosis
Activator protein 1
Brain-derived neurotrophic factor
CCAAT enhancer binding protein β1
Extracellular signal-regulated kinase ½
Glycogen synthase kinase 3 beta
Inhibitor of Nuclear factor kappa B kinase subunit beta
Interferon regulatory factor 8
Mitogen-activated protein kinase
Myelin oligodendrocyte glycoprotein
Nuclear factor kappa B subunit 1
NFKB inhibitor alpha
Nuclear receptor subfamily 3, group C, member 1/glucocorticoid receptor
Protein kinase C
Rel-like domain-containing proteins
Serum/glucocorticoid regulated kinase 1
Specificity protein 1
Signal transducer and activator of transcription 4
This work was supported in part by Grants (1R21NS082918 and R01 AT 004321) from the National Institutes of Health, Bethesda, MD and in part by VA Merit Review Award # 5 I01 BX002424 (to KDM) from the United States (U.S.) Department of Veterans Affairs [Biomedical Laboratory Research and Development Service]. We thank Jason Lees (USUHS, Bethesda) and Bodhraj Acharya (UMB) for helpful advice and discussion regarding the MOG-EAE model. We thank Rakeshchandra Reddy Meka and Steven Dudics for help with some experiments. We also thank Carol Fowler and Tom Bowen for help with the VA Research Facilities. This material is the result of work supported in part with resources and the use of facilities at the VA Maryland Health Care System, Baltimore, Maryland.
Compliance with ethical standards
Conflict of interest
The authors declare no conflict of interest. The contents do not represent the views of the U.S. Department of Veterans Affairs or the United States Government.
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