Identification of tissue-dependent proteins in knee OA synovial fluid

Abstract

Objective: For many proteins from osteoarthritic synovial fluid, their intra-articular tissue of origin remains unknown. In this study we performed comparative proteomics to identify osteoarthritis-specific and joint tissue-dependent secreted proteins that may serve as candidates for osteoarthritis biomarker development on a tissue-specific basis. Design: Protein secretomes of cartilage, synovium, Hoffa's fat pad and meniscus from knee osteoarthritis patients were determined using liquid chromatography tandem mass spectrometry, followed by labelfree quantification. Validation of tissue-dependent protein species was conducted by ELISA on independent samples. Differential proteomes of osteoarthritic and non-osteoarthritic knee synovial fluids were obtained via similar proteomics approach, followed by ELISA validation. Results: Proteomics revealed 64 proteins highly secreted from cartilage, 94 from synovium, 37 from Hoffa's fat pad and 21 from meniscus. Proteomic analyses of osteoarthritic vs non-osteoarthritic knee synovial fluid revealed 70 proteins with a relatively higher abundance and 264 proteins with a relatively lower abundance in osteoarthritic synovial fluid. Of the 70 higher abundance proteins, 23 were amongst the most highly expressed in the secretomes of a specific intra-articular tissue measured. Tissuedependent release was validated for SLPI, C8, CLU, FN1, RARRES2, MATN3, MMP3 and TNC. Abundance in synovial fluid of tissue-dependent proteins was validated for IGF2, AHSG, FN1, CFB, KNG and C8. Conclusions: We identified proteins with a tissue-dependent release from intra-articular human knee OA tissues. A number of these proteins also had an osteoarthritis-specific abundance in knee synovial fluid. These proteins may serve as novel candidates for osteoarthritis biomarker development on a tissuespecific basis.

Proteomics Profiling of Human Synovial Fluid Suggests Increased Protein Interplay in Early-Osteoarthritis (OA) That Is Lost in Late-Stage OA

“…Importantly, lymphatic vessels have only been detected in the synovium but not in the subchondral bone. The differential expression of these proteins that has originate from different compartments of the joint ( 62 ), suggests that molecular changes from the whole joint can be detected in synovial fluid. ZHX3 was increased in both early- and late-stage OA while LYVE1 was decreased in the OA patients in comparison to the controls.…”

Ribosome dysfunction in osteoarthritis

“…The balance between cap-dependent and IRES-dependent translation is amongst others determined by specific snoRNA-mediated PTMs on the rRNA [ 18 ] and by expression of IRES-transacting factors (ITAFs). With the mapping of differential expression of snoRNAs [ 14 , 22 ▪▪ , 23 , 26 , 50 ] and rRNA PTMs [ 25 ], as well as high-resolution proteomics [ 30 ▪▪ , 39 ] in cells from joint tissues as a function of ageing [ 51 , 52 ] and osteoarthritis, it is expected that insight into this level of ribosome translation regulation will further unfold. The existence of other mechanisms of preferential translation in cell types from the joint is only starting to emerge.…”

Histone H3K27 demethylase UTX compromises articular chondrocyte anabolism and aggravates osteoarthritic degeneration

“…From the H3K27me3 repressive signatures, Igf2 was selected for subsequent experiments (Fig. 6b ) as it is known to control cartilage development during postnatal bone growth [ 21 ] and correlate with human OA [ 22 ]. The spatial distribution of H3K27me3-binding sites in the coding sequence of Igf2 (Fig.…”