Peripherin: A proposed biomarker of traumatic axonal injury triggered by mechanical force.

Traumatic axonal injury (TAI) is one of the most common pathological features of severe traumatic brain injury (TBI). Our previous study using proteomics suggested that peripherin (PRPH) should be a potential candidate as a biomarker for TAI diagnosis. This study is to further elucidate the role and association of PRPH with TAI. In the animal study, we performed immunohistochemistry, ELISA and morphological analysis to evaluate PRPH level and distribution following a severe impact. PRPH-positive regions were widely distributed in the axonal tract throughout the whole brain. Axonal injuries with PRPH inclusion were observed post-TBI. Besides, PRPH was significantly increased in both cerebral spinal fluid and plasma at the early phase post-TBI. Colocalization analysis based on microscopy revealed that PRPH represents an immunohistological biomarker in the neuropathological diagnosis of TAI. Brain samples from patients with TBI were included to further test whether PRPH is feasible in the real practice of neuropathology. Immunohistochemistry of PRPH, NFH, APP and NFL on human brain tissues further confirmed PRPH as an immunohistological biomarker that could be applied in practice. Collectively, we conclude that PRPH mirrors the cytoskeleton injury of axons and could represent a neuropathological biomarker for TAI.