Reduced apoptosis correlates with enhanced autophagy

ORIGINAL RESEARCH PAPER

Reduced apoptosis correlates with enhanced autophagy in synovial tissues of rheumatoid arthritis

Ke Xu •Peng Xu •Jian-Feng Yao •Yin-Gang Zhang •

Wei-kun Hou •She-Min Lu

Received:12April 2012/Revised:15October 2012/Accepted:25October 2012/Published online:20November 2012ÓSpringer Basel 2012

Abstract

Objective Defective apoptosis contributes to the massive synovial hyperplasia in rheumatoid arthritis (RA),but the mechanism is largely unknown.To investigate the reasons for the reduced apoptosis in RA synovium,we analyzed autophagy and its relationship to apoptosis in synovial tissues from RA and osteoarthritis (OA)patients.

Methods Synovial tissues were obtained from seven RA and 12OA patients undergoing knee replacement surgery.Apoptosis was detected by the terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL)assay and staining for p85fragment of PolyADP-ribose polymerase (PARP).Autophagy was determined by immunoblotting for the autophagic markers Beclin-1and LC3.MicroRNA-30a (miR-30a),which targets Beclin-1,was measured by real-time RT-PCR.The interplay between autophagy and apoptosis was determined via Spearman’s correlation analysis.

Results In comparison with OA,the synovial tissues from RA displayed decreased TUNEL-positive nuclei

(P \0.01).In contrast,Beclin-1and LC3were overex-pressed in the synovial lining layers of RA,which was correlated with decreased levels of miR-30a.Moreover,there was a significant reverse relationship between apop-tosis and autophagy in RA synovial tissues (P \0.01and r =-0.8937).

Conclusion The impaired apoptosis in RA synovium might result from increased autophagy,which in turn could be due to the deregulation of miRNA-30a.Keywords Rheumatoid arthritis ÁOsteoarthritis ÁAutophagy ÁApoptosis ÁSynovium

Abbreviations H&E Hematoxylin–eosin OA Osteoarthritis OD Optical density PARP PolyADP-ribose polymerase RA Rheumatoid arthritis SF Synovial fibroblast TBST Tris-buffered saline with Tween 20TUNEL Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling

Introduction

Synovial hyperplasia,chronic inflammation,and autoim-mune reaction are the major histological features of rheumatoid arthritis (RA)[1],and the hyperplasia is the driving force behind the inflammatory and destructive responses [2].Accumulating data indicate that the massive synovial hyperplasia of RA results from defective (reduced)apoptosis [3,4];apoptosis is rarely found in the synovial tissues of either RA patients or animal models of

Responsible Editor:John Di Battista.

K.Xu ÁP.Xu (&)ÁJ.-F.Yao ÁW.Hou

Department of Joint Surgery,Hong Hui Hospital,Xi’an Jiaotong University College of Medicine,Xi’an 710054,China e-mail:sousou369@

Y.-G.Zhang

Department of Orthopedics,First Affiliated Hospital of Xi’an Jiaotong University College of Medicine,Xi’an 710061,China S.-M.Lu (&)

Department of Genetics and Molecular Biology,Xi’an Jiaotong University College of Medicine,Xi’an 710061,China e-mail:lushemin@

Inflamm.Res.(2013)62:229–237DOI 10.1007/s00011-012-0572-1

Inflammation Research