Poster Presentation 50th International Society for the Study of the Lumbar Spine Annual Meeting 2024

Periostin increased by mechanical stress upregulates interleukin-6 expression in the ligamentum flavum (#233)

Akito Yabu 1 , Akinobu Suzuki 1 , Hidetomi Terai 1 , Minori Kato 1 , Hiromitsu Toyoda 1 , Shinji Takahashi 1 , Koji Tamai 1 , Masayoshi Iwamae 1 , Hiroaki Nakamura 1
  1. Osaka Metropolitan University, ..., Japan

INTRODUCTION

Ligamentum flavum (LF) hypertrophy is a major cause of lumbar spinal canal stenosis (LSS). Although mechanical stress is thought to be a major factor involved in LF hypertrophy, the exact mechanism by which it causes hypertrophy has not yet been fully elucidated.The purpose of this study was to evaluate the changes in gene expression of LF due to mechanical stress by integrated transcriptome analysis and to analyze the functions of the extracted genes.

METHODS

New Zealand white rabbits were used to create a model of LF hypertrophy. In this model, spinal fusion of two adjacent segments increases intervertebral mechanical stress and causes the LF hypertrophy (Fig1). We performed comprehensive genetic analysis of molecules related to LF degenerative changes caused by mechanical stress concentration using microarrays (short-term (16 weeks) rabbit model) and RNA seq (long-term (1 year) rabbit model). Furthermore, these results were collated with previously reported gene expression profiles associated with human LF hypertrophy investigated using microarrays1). We focused on genes that were co-upregulated in all the datasets and gene expression levels in human LF tissue were analyzed by qPCR. Furthermore, among the extracted genes we focused on the periostin and investigated the effect of periostin in the pathophysiological mechanism underlying LF hypertrophy. The expression and function of periostin were investigated using human primary LF cell cultures.To investigate whether mechanical stress induces periostin and fibrosis-related factors(transforming growth factor-β1 (TGF-β1), α-smooth muscle actin (αSMA), collagen type 1 alpha 1 (Col1a1), and interleukin-6(IL-6)) expression in LF cells, fluid flow shear stress (FFSS) was applied to LF cells and analyzed by qPCR. In addition, the effects of Peristin treatement or periostin  blockade on IL-6 production were analyzed by qPCR.

RESULTS

Periostin, biglycan, and HAPLN1 were identified as genes involved in mechanical stress-caused LF hypertrophy (Fig2).The expression of three genes showed a significant positive correlation between human LF thickness, with periostin showing the highest correlation. Thus, further analyses were focused on periostin. In vitro, FFSS increased gene expressions of periostin,TGF-β1, αSMA, Col1a1 and IL-6 in LF cells. Periostin blockade suppressed the FFSS-induced upregulation of IL-6 gene expression while periostin treatment increased IL-6 gene expression.

DISCUSSION

Our results suggest that periostin is upregulated by mechanical stress and promotes inflammation by upregulating IL-6 expression, which leads to LF degeneration and hypertrophy. Periostin may be a pivotal molecule for LF hypertrophy and a promising therapeutic target for LSS.

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  1. 1)Zheng Z, Ao X, Li P, et al. CRLF1 is a key regulator in the ligamentum flavum hypertrophy. Front Cell Dev Biol 2020;8:858.