{"database":"biostudies-literature","file_versions":[],"scores":null,"additional":{"omics_type":["Unknown"],"volume":["84(6)"],"submitter":["Sillat T"],"pubmed_abstract":["<h4>Background and purpose</h4>Degenerating cartilage releases potential danger signals that react with Toll-like receptor (TLR) type danger receptors. We investigated the presence and regulation of TLR1, TLR2, and TLR9 in human chondrocytes.<h4>Methods</h4>We studied TLR1, TLR2, TLR4, and TLR9 mRNA (qRT-PCR) and receptor proteins (by immunostaining) in primary mature healthy chondrocytes, developing chondrocytes, and degenerated chondrocytes in osteoarthritis (OA) tissue sections of different OARSI grades. Effects of a danger signal and of a pro-inflammatory cytokine on TLRs were also studied.<h4>Results</h4>In primary 2D-chondrocytes, TLR1 and TLR2 were strongly expressed. Stimulation of 2D and 3D chondrocytes with a TLR1/2-specific danger signal increased expression of TLR1 mRNA 1.3- to 1.8-fold, TLR2 mRNA 2.6- to 2.8-fold, and TNF-? mRNA 4.5- to 9-fold. On the other hand, TNF-? increased TLR1 mRNA] expression 16-fold, TLR2 mRNA expression 143- to 201-fold, and TNF-? mRNA expression 131- to 265-fold. TLR4 and TLR9 mRNA expression was not upregulated. There was a correlation between worsening of OA and increased TLR immunostaining in the superficial and middle cartilage zones, while chondrocytes assumed a CD166(×) progenitor phenotype. Correspondingly, TLR expression was high soon after differentiation of mesenchymal stem cells to chondrocytes. With maturation, it declined (TLR2, TLR9).<h4>Interpretation</h4>Mature chondrocytes express TLR1 and TLR2 and may react to cartilage matrix/chondrocyte-derived danger signals or degradation products. This leads to synthesis of pro-inflammatory cytokines, which stimulate further TLR and cytokine expression, establishing a vicious circle. This suggests that OA can act as an autoinflammatory disease and links the old mechanical wear-and-tear concept with modern biochemical views of OA. These findings suggest that the chondrocyte itself is the earliest and most important inflammatory cell in OA."],"journal":["Acta orthopaedica"],"pagination":["585-92"],"full_dataset_link":["https://www.ebi.ac.uk/biostudies/studies/S-EPMC3851674"],"repository":["biostudies-literature"],"pubmed_title":["Toll-like receptors in human chondrocytes and osteoarthritic cartilage."],"pmcid":["PMC3851674"],"pubmed_authors":["Konttinen YT","Barreto G","Ainola M","Ylinen P","Pajarinen J","Sakalyte R","Sillat T","Nordstrom DC","Korhonen M","Hukkanen M","Clarijs P","Soininen A"],"additional_accession":[]},"is_claimable":false,"name":"Toll-like receptors in human chondrocytes and osteoarthritic cartilage.","description":"<h4>Background and purpose</h4>Degenerating cartilage releases potential danger signals that react with Toll-like receptor (TLR) type danger receptors. We investigated the presence and regulation of TLR1, TLR2, and TLR9 in human chondrocytes.<h4>Methods</h4>We studied TLR1, TLR2, TLR4, and TLR9 mRNA (qRT-PCR) and receptor proteins (by immunostaining) in primary mature healthy chondrocytes, developing chondrocytes, and degenerated chondrocytes in osteoarthritis (OA) tissue sections of different OARSI grades. Effects of a danger signal and of a pro-inflammatory cytokine on TLRs were also studied.<h4>Results</h4>In primary 2D-chondrocytes, TLR1 and TLR2 were strongly expressed. Stimulation of 2D and 3D chondrocytes with a TLR1/2-specific danger signal increased expression of TLR1 mRNA 1.3- to 1.8-fold, TLR2 mRNA 2.6- to 2.8-fold, and TNF-? mRNA 4.5- to 9-fold. On the other hand, TNF-? increased TLR1 mRNA] expression 16-fold, TLR2 mRNA expression 143- to 201-fold, and TNF-? mRNA expression 131- to 265-fold. TLR4 and TLR9 mRNA expression was not upregulated. There was a correlation between worsening of OA and increased TLR immunostaining in the superficial and middle cartilage zones, while chondrocytes assumed a CD166(×) progenitor phenotype. Correspondingly, TLR expression was high soon after differentiation of mesenchymal stem cells to chondrocytes. With maturation, it declined (TLR2, TLR9).<h4>Interpretation</h4>Mature chondrocytes express TLR1 and TLR2 and may react to cartilage matrix/chondrocyte-derived danger signals or degradation products. This leads to synthesis of pro-inflammatory cytokines, which stimulate further TLR and cytokine expression, establishing a vicious circle. This suggests that OA can act as an autoinflammatory disease and links the old mechanical wear-and-tear concept with modern biochemical views of OA. These findings suggest that the chondrocyte itself is the earliest and most important inflammatory cell in OA.","dates":{"release":"2013-01-01T00:00:00Z","publication":"2013 Dec","modification":"2021-03-05T09:32:10Z","creation":"2019-03-27T03:09:46Z"},"accession":"S-EPMC3851674","cross_references":{"pubmed":["24237425"],"doi":["10.3109/17453674.2013.854666"]}}