First description of enhanced expression of transforming growth factor-alpha (TGF-alpha) and glia maturation factor-beta (GMF-beta) correlate with severity of neuropathology in border disease virus-infected small ruminants

Abstract

Border disease (BD) is caused by Pestivirus and characterized by severe neuropathology, and histopathologically observed severe hypomyelination. We have previously shown that small ruminants infected with border disease virus (BDV) play an important role for neuropathology and pathogenesis of severe oxidative damage in brain tissue, neuronal mtDNA; in the production of high pathologic levels of nitric oxide; in glial cell activation and stimulation of intrinsic apoptosis pathway. This study aimed to investigate the relationship between glia maturation factor beta (GMF-beta) and transforming growth factor alpha (TGF-alpha) expressions and the causes of BDV-induced neuropathology and to investigate their role in neuropathogenesis in a way that was not presented before. Expression levels of GMF-beta and TGF-alpha were investigated. Results of the study revealed that the levels of GMF-beta (P < 0.005) and TGF-alpha (P < 0.005) expression in the brain tissue markedly increased in the BDV-infected animals compared to the non-infected healthy control group. While TGF-alpha expressions were predominantly observed in neurons, GMF-beta expressions were found in astrocytes, glial cells and neurons. These results were reasonable to suggest that BDV-mediated increased GMF-beta might play a pivotal role neuropathogenesis and a different type of role in the mechanism of neurodegeneration/neuropathology in the process of BD. The results also indicated that increased levels of GMF up-regulation in glial cells and neurons causes neuronal destruction, suggesting pathological pathway involving GMF-mediated brain cell cytotoxicity. It is clearly indicated that the cause of astrogliosis is due to severe TGF-alpha expression. This is the first study to demonstrate the expression of GMF-beta and TGF-alpha in neurons and reactive glial cells and its association with neuropathology in BD.