Inhibition of Rho Family Functions by Lovastatin Promotes Myelin Repair in Ameliorating Experimental Autoimmune Encephalomyelitis

Abstract

Impaired remyelination is critical to neuroinflammation in multiple sclerosis (MS), which causes chronic and relapsing neurological impairments. Recent studies revealed that immunomodulatory activity of statins in an experimental autoimmune encephalomyelitis (EAE) model of MS are via depletion of isoprenoids (farnesyl-pyrophosphate and geranylgeranyl-pyrophosphate) rather than cholesterol in immune cells. In addition, we previously documented that lovastatin impedes demyelination and promotes myelin repair in treated EAE animals. To this end, we revealed the underlying mechanism of lovastatin-induced myelin repair in EAE using in vitro and in vivo approaches. Survival, proliferation (chondroitin sulfate proteoglycan-NG2 ϩ and late oligodendrocyte progenitor marker ϩ ), and terminal-differentiation (myelin basic protein ϩ ) of OPs was significantly increased in association with induction of a promyelinating milieu by lovastatin in mixed glial cultures stimulated with proinflammatory cytokines. Lovastatin-induced effects were reversed by cotreatment with mevalonolactone or geranylgeranyl-pyrophosphate, but not by farnesyl-pyrophosphate or cholesterol, suggesting that depletion of geranygeranyl-pyrophosphate is more critical than farnesyl-pyrophosphate in glial cells. These effects of lovastatin were mimicked by inhibitors of geranylgeranyl-transferase (geranylgeranyl transferase inhibitor-298) and downstream effectors {i.e., Rho-family functions (C3-exoenzyme) and Rho kinase [Y27632 (N-(4-pyridyl)-4-(1-aminoethyl)cyclohexanecarboxamide dihydrochloride)]} but not by an inhibitor of farnesyl-transferase (farnesyl transferase inhibitor-277). Moreover, activities of Rho/Ras family GTPases were reduced by lovastatin in glial cells. Corresponding with these findings, EAE animals exhibiting demyelination (on peak clinical day; clinical scores Ն3.0) when treated with lovastatin and aforementioned agents validated these in vitro findings. Together, these data provide unprecedented evidence that-like immune cells-geranylgeranyl-pyrophosphate depletion and thus inhibition of Rho family functions in glial cells by lovastatin promotes myelin repair in ameliorating EAE.Multiple sclerosis (MS) is a neurodegenerative disease characterized by inflammation, gliosis, demyelination, and loss of both neuronal axons and oligodendrocytes (OL) (Lassmann et al., 2001). The involvement of various cells types and metabolites in MS pathology suggests that myelin repair (remyelination) can occur in the acute inflammatory phase when damage may be reversed, but it is impaired in the later

RGMA and IL21R show association with experimental inflammation and multiple sclerosis

“…[42][43][44] Inhibition of Rho family functions has been shown to ameliorate EAE in rats, associated with promotion of myelin repair, inhibition of leukocyte infiltration into the central nervous system and a reduced axonal damage. [45][46][47] The strong expression of RhoA in active MS lesions and low expression in chronic MS lesions suggest that RhoA also has a role in MS. 47 We can thus hypothesize that variants of RGMA through differential regulation of RhoA result in different immune activation and disease outcome. In contrast to Eae30, Eae31/Pia32 showed linkage with two organ-specific diseases, EAE and PIA.…”

S-Nitrosoglutathione Induces Ciliary Neurotrophic Factor Expression in Astrocytes, Which Has Implications to Protect the Central Nervous System under Pathological Conditions

“…Gene-specific primer for rat gene sequences (␤-actin, forward primer (FP) 5Ј-agagaagctgtgctatgttgccct-3Ј and reverse primer (RP) 5Ј-accgctcattgccgatagtgatga-3Ј; GFAP, FP 5Ј-agaaggccacctcaagaggaacat-3Ј and RP 5Ј-ttaggccctcacactgtatggcaa-3Ј; myelin basic protein (MBP), FP 5Ј-ctctggcaaggactcacacac-3Ј and RP 5Ј-tctgctgagggacaggcctctc-3; CNTF, FP cttcaagagctctcacagtg-3Ј and RP tgcttatctttggccccataat-3Ј; insulin-like growth factor-1 (IGF-1), FP 5Ј-tgacatgcccaagactcagaagga-3Ј and RP 5Ј-ggttgctcaagcagcaaaggatct-3Ј; leukemia inhibitory factor (LIF); FP 5Ј-tcacggcaacctcatgaaccagatwere-3Ј and RP 5Ј-ccat-tggcatggaaaggtgggaaa-3Ј; COX-2; FP 5Ј-atcgatgccatggaactgtatccc-3Ј and RP, 5Ј-ctcttacagctcagttgaacgcct-3Ј) were designed using Primer Quest software and purchased from Integrated DNA Technologies (Coralville, IA). Thermal cycling conditions were as follows: activation of iTaq TM DNA polymerase in SYBR Green super mix at 95°C for 10 min followed by 40 cycles of amplification at 95°C for 30 s and 59 -60°C for 45-60 s. The specificity and detection methods for data analysis are as described earlier (36).…”

Lipid metabolism in myelinating glial cells: lessons from human inherited disorders and mouse models

“…Importantly, statins are widely used for the treatment of hypercholesterolemia, and some statins, e.g., Lovastatin and Simvastatin, are able to cross the blood-brain barrier ( 139 ). Remarkably, statins can ameliorate remyelination in an animal model of multiple sclerosis (MS) (140)(141)(142)(143), possibly via augmenting survival and differentiation of oligodendrocyte progenitors, and therefore have been tested in MS trials ( 144,145 ). However, statins induce the formation of abnormal myelin-like membrane sheets in primary oligodendrocytes in vitro, due to impairment of cholesteroldependent myelin protein transport ( 146 ), which indicates a risk of the use of statins for myelin membrane integrity.…”