title: Thymosin Beta-4 Suppresses Osteoclastic Differentiation and Inflammatory Responses in Human Periodontal Ligament Cells.
abstract: BACKGROUND
  Recent reports suggest that thymosin beta-4 (Tβ4) is a key regulator for wound healing and anti-inflammation. However, the role of Tβ4 in osteoclast differentiation remains unclear.
  
  
  OBJECTIVE
  The purpose of this study was to evaluate Tβ4 expression in H2O2-stimulated human periodontal ligament cells (PDLCs), the effects of Tβ4 activation on inflammatory response in PDLCs and osteoclastic differentiation in mouse bone marrow-derived macrophages (BMMs), and identify the underlying mechanism.
  
  
  METHODS
  Reverse transcription-polymerase chain reactions and Western blot analyses were used to measure mRNA and protein levels, respectively. Osteoclastic differentiation was assessed in mouse bone marrow-derived macrophages (BMMs) using conditioned medium (CM) from H2O2-treated PDLCs.
  
  
  RESULTS
  Tβ4 was down-regulated in H2O2-exposed PDLCs in dose- and time-dependent manners. Tβ4 activation with a Tβ4 peptide attenuated the H2O2-induced production of NO and PGE2 and up-regulated iNOS, COX-2, and osteoclastogenic cytokines (TNF-α, IL-1β, IL-6, IL-8, and IL-17) as well as reversed the effect on RANKL and OPG in PDLCs. Tβ4 peptide inhibited the effects of H2O2 on the activation of ERK and JNK MAPK, and NF-κB in PDLCs. Furthermore, Tβ4 peptide inhibited osteoclast differentiation, osteoclast-specific gene expression, and p38, ERK, and JNK phosphorylation and NF-κB activation in RANKL-stimulated BMMs. In addition, H2O2 up-regulated Wnt5a and its cell surface receptors, Frizzled and Ror2 in PDLCs. Wnt5a inhibition by Wnt5a siRNA enhanced the effects of Tβ4 on H2O2-mediated induction of pro-inflammatory cytokines and osteoclastogenic cytokines as well as helping osteoclastic differentiation whereas Wnt5a activation by Wnt5a peptide reversed it.
  
  
  CONCLUSIONS
  In conclusion, this study demonstrated, for the first time, that Tβ4 was down-regulated in ROS-stimulated PDLCs as well as Tβ4 activation exhibited anti-inflammatory effects and anti-osteoclastogenesis in vitro. Thus, Tβ4 activation might be a therapeutic target for inflammatory osteolytic disease, such as periodontitis.
authors.affiliation: Department of Dental Hygiene, School of Health Sciences, Dankook University, Cheonan, Republic of Korea.
authors.forename: Sang-Im
authors.initials: SI
authors.lastname: Lee
authors.affiliation: Department of Conservative Dentistry, School of Dentistry, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Jin-Kyu
authors.initials: JK
authors.lastname: Yi
authors.affiliation: Department of Oral and Maxillofacial Pathology and Research Center for Tooth and Periodontal Regeneration (MRC), School of Dentistry, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Won-Jung
authors.initials: WJ
authors.lastname: Bae
authors.affiliation: Department of Oral Physiology, School of Dentistry, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Soojung
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Parasitology and Genetics, College of Medicine, Kosin University Busan, Republic of Korea.
authors.forename: Hee-Jae
authors.initials: HJ
authors.lastname: Cha
authors.affiliation: Department of Oral and Maxillofacial Pathology and Research Center for Tooth and Periodontal Regeneration (MRC), School of Dentistry, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Eun-Cheol
authors.initials: EC
authors.lastname: Kim
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects*; D002461:Cell Line, Transformed; D016207:Cytokines / Q000378:metabolism; D005260:Female; D006801:Humans; D006861:Hydrogen Peroxide / Q000009:adverse effects / Q000494:pharmacology; D007249:Inflammation / Q000139:chemically induced / Q000378:metabolism / Q000473:pathology; D020935:MAP Kinase Signaling System / Q000187:drug effects; D051379:Mice; D008813:Mice, Inbred ICR; D010010:Osteoclasts / Q000378:metabolism* / Q000473:pathology; D010513:Periodontal Ligament / Q000378:metabolism* / Q000473:pathology; D013947:Thymosin / Q000494:pharmacology*; D000099201:Thymosin beta(4)
chemical_list: D016207:Cytokines; D006861:Hydrogen Peroxide; D013947:Thymosin; D000099201:Thymosin beta(4)