title: Expression of hedgehog signal pathway in articular cartilage is associated with the severity of cartilage damage in rats with adjuvant-induced arthritis.
abstract: BACKGROUND
  Cartilage damage is a crucial step in rheumatoid arthritis (RA) disease progress while its molecular mechanisms are not fully understood. Here we investigated the expression of hedgehog (Hh) signal pathway in articular cartilage of adjuvant-induced arthritis (AIA) rats and its possible pathological role in cartilage damage.
  
  
  METHODS
  30 rats were divided into sham and AIA group (n = 15). Complete Freund's adjuvant was used to induce AIA. Secondary paw swelling was measured on day 10, 14, 18, 22 and 26 after induction. Rats were sacrificed on day 26 and knee joints and cartilage tissues were collected. Paw swelling, cartilage histopathologic changes and OARSI scores were used to evaluate AIA in rats. The protein expression of Hh signal related genes (Shh, Ptch1, Smo and Gli1) in cartilage were assayed by immunohistochemistry. The mRNA levels of Shh, Ptch1, Smo, Gli1, type-II collagen (COII) and aggrecan in cartilage were assayed by real-time PCR. In vitro study, cultured AIA chondrocytes were treated with cyclopamine (a specific inhibitor of Hh signal) and the mRNA levels of Hh signal and ECM components (COII and aggrecan) were measured by real-time PCR.
  
  
  RESULTS
  Immunohistochemical results revealed that Shh, Ptch1, Smo and Gli1 proteins showed higher expression in the articular cartilage of AIA rats than those of sham rats. Real-time PCR results confirmed that Shh, Ptch1, Smo and Gli1 mRNA levels in cartilage tissues of AIA rats were significantly increased compared with those of sham rats (1.6, 1.4, 1.6, 2.0 fold, respectively). The mRNA levels of Shh, Ptch1, Smo, and Gli1 were associated with the severity of cartilage damage (indicated by OARSI scores, COII and aggrecan mRNA levels in cartilage). In vitro, cyclopamine effectively decreased the mRNA levels of Shh, Ptch1, Smo and Gli1, and increased the mRNA levels of COII and aggrecan in AIA chondrocytes, suggesting Hh signal inhibition might directly promote ECM production.
  
  
  CONCLUSIONS
  Our findings present certain experimental evidence that Hh signal pathway is involved in the pathogenesis of cartilage damage in RA.
authors.affiliation: School of Pharmacy, Anhui Medical University, 81 Meishan Road, Hefei, 230032 Anhui China ; Key Laboratory for Bioactivity of Natural Medicine of Anhui Province, Hefei, 230032 Anhui China.
authors.forename: Rong
authors.initials: R
authors.lastname: Li
authors.affiliation: Department of Pathology, School of Basic Medicine, Anhui Medical University, 81 Meishan Road, Hefei, 230032 Anhui China.
authors.forename: Li
authors.initials: L
authors.lastname: Cai
authors.affiliation: School of Pharmacy, Anhui Medical University, 81 Meishan Road, Hefei, 230032 Anhui China ; Key Laboratory for Bioactivity of Natural Medicine of Anhui Province, Hefei, 230032 Anhui China.
authors.forename: Cheng-Mu
authors.initials: CM
authors.lastname: Hu
authors.affiliation: School of Pharmacy, Anhui Medical University, 81 Meishan Road, Hefei, 230032 Anhui China ; Key Laboratory for Bioactivity of Natural Medicine of Anhui Province, Hefei, 230032 Anhui China.
authors.forename: Ting-Ni
authors.initials: TN
authors.lastname: Wu
authors.affiliation: School of Pharmacy, Anhui Medical University, 81 Meishan Road, Hefei, 230032 Anhui China ; Key Laboratory for Bioactivity of Natural Medicine of Anhui Province, Hefei, 230032 Anhui China.
authors.forename: Jun
authors.initials: J
authors.lastname: Li
keywords: Adjuvant-induced arthritis; Articular cartilage; Hedgehog signal pathway; Inflammation; Rheumatoid arthritis
references.citation: Cell Physiol Biochem. 2006;18(1-3):35-46
references.pmid: 16914888
references.citation: Osteoarthritis Cartilage. 2010 Oct;18 Suppl 3:S24-34
references.pmid: 20864021
references.citation: Br J Cancer. 2008 May 20;98 (10 ):1670-4
references.pmid: 18475300
references.citation: Arthritis Rheum. 2010 Aug;62(8):2192-205
references.pmid: 20506322
references.citation: Methods. 2001 Dec;25(4):402-8
references.pmid: 11846609
references.citation: Nat Med. 2009 Dec;15(12 ):1421-5
references.pmid: 19915594
references.citation: Eur Neuropsychopharmacol. 2010 Dec;20(12):839-47
references.pmid: 20659790
references.citation: J Immunol Res. 2014;2014:401903
references.pmid: 24741597
references.citation: Arthritis Res Ther. 2008;10(1):R9
references.pmid: 18205922
references.citation: J Rehabil Res Dev. 2000 Mar-Apr;37(2):145-51
references.pmid: 10850820
references.citation: Nature. 2003 Oct 23;425(6960):846-51
references.pmid: 14520411
references.citation: Ann Rheum Dis. 2009 Jul;68(7):1197-200
references.pmid: 18713784
references.citation: Inflamm Res. 2010 Nov;59(11):939-47
references.pmid: 20454829
references.citation: Development. 2008 Jun;135(11):1947-56
references.pmid: 18434416
references.citation: Osteoarthritis Cartilage. 2007 Nov;15(11):1241-8
references.pmid: 17576080
references.citation: J Inflamm (Lond). 2010 Aug 11;7:41
references.pmid: 20701804
references.citation: Mod Rheumatol. 2006;16(4):197-205
references.pmid: 16906368
references.citation: PLoS One. 2014 Feb 12;9(2):e88550
references.pmid: 24533105
references.citation: Immunopharmacol Immunotoxicol. 2012 Apr;34(2):326-36
references.pmid: 21970621
references.citation: Development. 2010 Jul;137(13):2079-94
references.pmid: 20530542
references.citation: Inflamm Res. 2012 Aug;61(8):875-87
references.pmid: 22538965
references.citation: Dev Cell. 2008 May;14(5):674-88
references.pmid: 18477451
references.citation: Biomaterials. 2000 Mar;21(5):431-40
references.pmid: 10674807
references.citation: J Bone Joint Surg Am. 2008 Feb;90 Suppl 1:19-24
references.pmid: 18292352
references.citation: Inflammation. 2012 Aug;35(4):1314-21
references.pmid: 22395729
references.citation: J Inflamm (Lond). 2012 Nov 20;9(1):44
references.pmid: 23167819
references.citation: Proc Natl Acad Sci U S A. 2007 Apr 10;104(15):6382-7
references.pmid: 17409191
references.citation: Nature. 2000 Aug 31;406(6799):1005-9
references.pmid: 10984056
references.citation: Nat Rev Cancer. 2003 Dec;3(12):903-11
references.pmid: 14737121
references.citation: Ann Rheum Dis. 2011 May;70(5):733-9
references.pmid: 21321002
references.citation: Osteoarthritis Cartilage. 2012 Jul;20(7):755-63
references.pmid: 22469853
references.citation: Eur Cell Mater. 2006 Nov 30;12:92-101
references.pmid: 17136680