Progranulin derived engineered protein Atsttrin suppresses TNF-α-mediated inflammation in intervertebral disc degenerative disease

Atsttrin, an engineered molecule composed of three fragments of progranulin(PGRN), exerts comparable anti-inflammation ability. Intervertebral disc degeneration (IDD) is involved in inflammation in which TNF-alpha plays a key role. This study aims to examine the effect and the mechanism of Atsttrin in the pathogenesis of intervertebral disc degeneration. For this purpose, we took advantage of murine and human intervertebral disc (IVD) and examined the expression of TNF-alpha in IVD tissues using immunohistochemistry and TNF-alpha level in peripheral sera by ELISA assay. Moreover, murine IVD was taken to undergo the Safranin O and HE staining. Furthermore, primary human nucleus pulposus cells were used for immunohistochemistry staining, fluorescent staining, Western Blot, ELISA assay and RT-PCR assay. Herein we found TNF-alpha expression was elevated in intervertebral disc and peripheral sera in patients with IDD. Interestingly, Atsttrin effectively inhibited TNF-alpha-mediated catabolism in murine disc by ex vivo study. TNF-alpha-induced inflammatory cytokines were strongly reduced in presence of Atsttrin in primary human disc. Mechanism study indicated Atsttrin protected against intervertebral disc degeneration by inhibiting TNF-alpha-induced inflammation. These findings show that Atsttrin is a potential molecular target for disc degenerative diseases.