Infrapatellar fat pad adipose tissue-derived macrophages displays a predominant CD11c+CD206+ phenotype and expresses genotypes attributable to key features of OA pathogenesis
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ABSTRACT: In knee osteoarthritis (OA), macrophages are the most predominant immune cells that infiltrate synovial tissues and IPFPs. Both M1 and M2 macrophages have been described, but their role in OA have not been fully investigated. Therefore, we investigated macrophage subpopulations in IPFPs and synovial tissues of knee OA patients and their correlation with disease severity, examined their transcriptomics and tested for factors that influenced their polarization.
Project description:Infrapatellar fat pad adipose tissue-derived macrophages displays a predominant CD11c+CD206+ phenotype and expresses genotypes attributable to key features of OA pathogenesis
Project description:The underlying molecular mechanisms in osteoarthritis (OA) development are largely unknown. This study explores the proteome and the pairwise interplay of proteins on a global level in synovial fluid from patients with late-stage knee OA (arthroplasty), early knee OA (arthroscopy due to degenerative meniscal tear) and from deceased controls without knee OA. Synovial fluid samples were analyzed using state-of-the-art mass spectrometry with data-independent acquisition. The differential expression of the proteins detected was clustered and evaluated with data mining strategies and a multilevel model. Group-specific slopes of associations were estimated between expressions of each pair of identified proteins to assess the co-expression (i.e. interplay) between the proteins in each group. More proteins were increased in early-OA vs controls than late-stage OA vs controls. For most of these proteins, the fold changes between late-stage OA vs controls and early stage OA vs controls were remarkably similar suggesting potential involvement in the OA process. Further, for the first time this study illustrated distinct patterns in protein co-expression suggesting that the global interplay between the protein machinery is increased in early-OA and lost in late-stage OA. Further efforts should probably focus on earlier stages of the disease than previously considered.
Project description:ObjectivesIn knee osteoarthritis (OA), macrophages are the most predominant immune cells that infiltrate synovial tissues and infrapatellar fat pads (IPFPs). Both M1 and M2 macrophages have been described, but their role in OA has not been fully investigated. Therefore, we investigated macrophage subpopulations in IPFPs and synovial tissues of knee OA patients and their correlation with disease severity, examined their transcriptomics, and tested for factors that influenced their polarization.MethodsSynovial tissues and IPFPs were obtained from knee OA patients undergoing total knee arthroplasty. Macrophages isolated from these joint tissues were characterized via flow cytometry. Transcriptomic profiling of each macrophage subpopulations was performed using NanoString technology. Peripheral blood monocyte-derived macrophages (MDMs) were treated with synovial fluid and synovial tissue- and IPFP-conditioned media. Synovial fluid-treated MDMs were treated with platelet-rich plasma (PRP) and its effects on macrophage polarization were observed.ResultsOur findings show that CD11c+CD206+ macrophages were predominant in IPFPs and synovial tissues compared to other macrophage subpopulations (CD11c+CD206-, CD11c-CD206+, and CD11c-CD206- macrophages) of knee OA patients. The abundance of macrophages in IPFPs reflected those in synovial tissues but did not correlate with disease severity as determined from Mankin scoring of cartilage destruction. Our transcriptomics data demonstrated highly expressed genes that were related to OA pathogenesis in CD11c+CD206+ macrophages than CD11c+CD206-, CD11c-CD206+, and CD11c-CD206- macrophages. In addition, MDMs treated with synovial fluid, synovial tissue-conditioned media, or IPFP-conditioned media resulted in different polarization profiles of MDMs. IPFP-conditioned media induced increases in CD86+CD206+ MDMs, whereas synovial tissue-conditioned media induced increases in CD86+CD206- MDMs. Synovial fluid treatment (at 1:8 dilution) induced a very subtle polarization in each macrophage subpopulation. PRP was able to shift macrophage subpopulations and partially reverse the profiles of synovial fluid-treated MDMs.ConclusionOur study provides an insight on the phenotypes and genotypes of macrophages found in IPFPs and synovial tissues of knee OA patients. We also show that the microenvironment plays a role in driving macrophages to polarize differently and shifting macrophage profiles can be reversed by PRP.
Project description:Synovial inflammation is associated with pain severity in patients with knee osteoarthritis (OA). The aim here was to determine in a population with knee OA, whether synovial tissue from areas associated with pain exhibited different synovial fibroblast subsets, compared to synovial tissue from sites not associated with pain. A further aim was to compare differences between early and end-stage disease synovial fibroblast subsets. Parapatellar synovitis was significantly associated with the pattern of patient-reported pain in knee OA patients. Synovial tissue from sites of patient-reported pain exhibited a differential transcriptomic phenotype, with distinct synovial fibroblast subsets in early OA and end-stage OA. Functional pathway analysis revealed that synovial tissue and fibroblast subsets from painful sites promoted fibrosis, inflammation and the growth and activity of neurons. The secretome of fibroblasts from early OA painful sites induced neurite outgrowth in dorsal root ganglion neurons. Sites of patient-reported pain in knee OA is associated with a different synovial tissue phenotype and distinct synovial fibroblast subsets. Further interrogation of these fibroblast pathotypes will increase our understanding of the role of synovitis in OA joint pain and provide a rationale for the therapeutic targeting of fibroblast subsets to alleviate pain in patients.
Project description:Background: Synovial inflammation is associated with pain severity in patients with knee osteoarthritis (OA). The aim here was to determine in a population with knee OA, whether synovial tissue from areas associated with pain exhibited different synovial fibroblast transcriptomes, compared to synovial tissue from sites not associated with pain. A further aim was to compare differences between early and end-stage disease synovial fibroblasts. Methods: Patients with early knee OA (n=29) and end-stage knee OA (n=22) were recruited. Patient reported pain was recorded by questionnaire and using an anatomical knee pain map. Proton density fat suppressed MRI axial and sagittal sequences were analysed and scored for synovitis. Synovial tissue was obtained from the medial and lateral parapatellar and suprapatellar sites. RNA sequencing was performed using Illumina’s NextSeq 500 and analysed with Galaxy web platform, usegalaxy.org, and Qlucore software. Transcriptomes were functionally characterised using Ingenuity Pathway Analysis. Findings: Parapatellar synovitis was significantly associated with increased OA pain perception. Functional pathway analysis revealed that early OA painful sites mediate immune cell recruitment and promote the formation and development of neurites. Conclusion: OA disease progression and the presence of pain in early OA is associated with different synovial pathotypes. Further interrogation of these pathotypes will increase our understanding of the role of synovitis in OA joint pain and provide a rationale for the therapeutic targeting to alleviate pain in patients.
Project description:Osteoarthritis (OA) causes pain and functional disability for over 500 million people worldwide and is characterized by progressive loss of cartilage and synovial hyperplasia from the articulating surfaces of diarthrodial joints. Although the etiology of the disease is unknown, it is widely accepted that these degenerative changes arise from an imbalance of synthetic and degradative pathways that control cartilage and synovium extracellular matrix metabolism. Genome-wide U133A Affymetrix oligonucleotide array set was used to comprehensively investigate the expression pattern in non-osteoarthritis (normal) and synovium obtained from OA and rheumatoid arthritis (RA) patients undergoing knee replacement surgery. This study was undertaken to understand the disease's molecular basis better and provide relevant insight into phenotypical alterations and mechanisms involved in OA pathogenesis.
Project description:To classify knee osteoarthritis (OA) synoviums according to gene expression patterns, we performed RNA-seq using synovial tissues obtained from OA patients and non-OA patients.
Project description:The aim of this study was to compare the gene expression pattern of synovial cells from inflammatory (I) or normal/reactive (N/R) areas of a synovial membrane harvested from the same osteoarthritis (OA) patient. This study is the first to identify different expression pattern between two areas of the synovial membrane in the same patient. These differences concern several key pathways involved in OA pathogenesis (inflammation, cartilage metabolism, Wnt signaling and angiogenesis). This analysis also provides interesting information regarding new potent intermediates as potentiel targets for the future therapeutic. Synovial tissues were obtained from 12 knee OA patients at the time of total knee replacement. The inflammatory status of the synovial membrane was characterized according to macroscopic criteria and sorted as N/R and I. Biopsies were cultured separately for 7 days. Microarray gene expression profiling between N/R and I areas was performed.
Project description:To classify knee osteoarthritis (OA) synoviums according to gene expression patterns, we performed single cell RNA-seq using synovial tissues obtained from OA patients.
Project description:Objective: To identify and characterize celltypes and distinct transcriptomic signatures present in the infrapatellar fat pad (IFP) of knee OA patients using single-nucleus RNA sequencing.