TNF and intervertebral disk degenerative disorder: Common differentially expressed orthologous mouse genes in Theiler’s murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD), myelin oligodendrocyte glycoprotein (MOG)- and proteolipid protein (PLP)-induced experimental autoimmune encephalomyelitis (EAE), tumor necrosis factor-overexpressing mice (TNFtg), and multiple sclerosis (MS).