Time Course and Spatial Profile of Nogo-A Expression in Experimental Autoimmune Encephalomyelitis in C57BL/6 Mice

Abstract

Inhibition of the myelin-associated neurite outgrowth inhibitor Nogo-A has been found to be beneficial in experimental autoimmune encephalomyelitis (EAE), but there are little data on its expression dynamics during the disease course. We analyzed Nogo-A mRNA and protein during the course of EAE in 27 C57BL/6 mice and in 8 controls. Histopathologic and molecular analyses were performed on Day 0 (naive), preclinical (Day 10), acute (Days 18-22) and chronic (Day 50) time points. In situ hybridization and real-time polymerase chain reaction analyses revealed reduced Nogo-A mRNA expression at preclinical (p < 0.0001) and acute phases (p < 0.0001), followed by upregulation during the chronic phase (p < 0.0001). Nogo-A mRNA was expressed in neurons and oligodendrocytes. By immunohistochemistry and Western blot, there was increased Nogo-A protein expression (p < 0.001) in the chronic phase. Moreover, spatial differences were observed within EAE lesions. The pattern of Nogo-A protein expression inversely correlated with axonal regeneration growth-associated protein 43-positive axons (60% of which were Nogo-A contact-free during the acute phase) and axonal injury (β-amyloid precursor protein-positive axons). Cortical Nogo-66 receptor protein and mRNA levels increased during the chronic phase. The results indicate that Nogo-A and Nogo receptor are actively regulated in EAE lesions; this may indicate a specific time window for localized axonal regeneration in the acute phase of EAE.

Nogo-A Antibodies for Progressive Multiple Sclerosis

“…This is consistent with findings in EAE mice [89]. Elevated serum and cerebrospinal fluid (CSF) autoantibody levels against the large N-terminal domain of Nogo-A have been found in blood samples from MS patients [101], but anti-Nogo-A antibodies exist also in healthy controls.…”

“…Interestingly, Nogo-A mRNA and protein levels were observed to be inversely correlated with those of the axonal growth marker GAP43 at different stages of the course of EAE [89]. This work showed that Nogo-A mRNA expression is reduced at preclinical and acute phases, which is followed by upregulation of mRNA and protein during the chronic EAE stage.…”

Zuo-Gui and You-Gui pills, two traditional Chinese herbal formulas, downregulated the expression of NogoA, NgR, and RhoA in rats with experimental autoimmune encephalomyelitis

“…Inflammatory lesions of these diseases have been shown to result in demyelination and axonal damage, and inhibition of the NogoA-NgR-RhoA signaling pathways prevents new growth cone formation (Satoh et al, 2005;Zhang et al, 2008). In addition, increased NogoA and NgR mRNA and protein have been observed in the chronic phase of EAE (Theotokis et al, 2012). In the study, accumulation of RhoA ( þ) cells was maximal in EAE rat brains during the acute stage, and this upregulation was sustained until the recovery stage of the disease.…”

New Insights into the Roles of Nogo-A in CNS Biology and Diseases

“…Blockade of the downstream signaling pathway of Nogo-A by changing the phosphorylation status of CRMP-2 was reported beneficial to MS [50]. Nogo-A and its receptors were once only believed to be up-regulated in the demyelinating lesions of MS [8], but they are now also found to be related with the progression of EAE [7]. The Ozanezumab (GSK1223249), an anti-Nogo-A antibody which is produced by GlaxoSmithKline in the treatment of MS and ALS is now under phase II clinical trials [139].…”

“…It also plays a critical role in the regulation of adhesive and repulsive interactions between cells in radial migration during cortical development [5], as well as in the regulation of synaptic plasticity and cognitive functions, from many aspects such as the dendritic morphology, synaptic transmission, intrinsic excitability and spontaneous firing, which when blocked would finally result in distinct behaviors resembling neuropsychiatric phenotypes [6]. For example, both Nogo-A and NgR were found to be up-regulated in EAE [7] and MS [8]. Accumulation of myelin debris from the oligodentrocytes that highly express Nogo-A and other myelin-derived inhibitory protein like MAG and OMgp, would play a critical role in the axonal growth inhibition, and the debris might also inhibit other oligodentrocytes' remyelination on the naked axon [9].…”