Project description:This dataset contains the transcriptional analysis of lining macrophages and sub-lining macrophages from vehicle or antigen-induced arthritis(AIA) mouse model.
Project description:While prior work has established that articular cartilage arises from Prg4-expressing perichondrial cells, it is not clear how this process is specifically restricted to the perichondrium of synovial joints. We document that the transcription factor Creb5 is necessary to initiate the expression of signaling molecules that both direct the formation of synovial joints and guide perichondrial tissue to form articular cartilage instead of bone. Creb5 promotes the generation of articular chondrocytes from perichondrial precursors in part by inducing expression of Wif1, which blocks a Wnt5a autoregulatory loop in the perichondrium. Postnatal deletion of Creb5 in the articular cartilage leads to loss of both flat superficial zone articular chondrocytes coupled with a loss of both Prg4 and Wif1 expression; and a non-cell autonomous up-regulation of Ctgf. Our findings indicate that Creb5 promotes both joint formation and the subsequent development of articular chondrocytes by disrupting a Wnt5a positive-feedback loop in the perichondrium.
Project description:Articular cartilage is deprived of blood vessels and nerves, and the only cells residing in this tissue are chondrocytes. The molecular properties of the articular cartilage and the architecture of the extracellular matrix demonstrate a complex structure that differentiates on the depth of tissue. Osteoarthritis (OA) is a degenerative joint disease, the most common form of arthritis, affecting the whole joint. It is associated with ageing and affects the joints that have been continually stressed throughout life including the knees, hips, fingers, and lower spine region. OA is a multifactorial condition of joint characterised by articular cartilage loss, subchondral bone sclerosis, and inflammation leading to progressive joint degradation, structural alterations, loss of mobility and pain. Articular cartilage biology is well studied with a focus on musculoskeletal diseases and cartilage development. However, there are relatively few studies focusing on zonal changes in the cartilage during osteoarthritis.
Project description:Macrophages (MΦs) are considered to contribute to chronic inflammatory diseases such as rheumatoid arthritis 1. However, both the exact origin and role of MΦs during inflammatory joint disease remain unclear. Here, we used multiple fate-mapping approaches in conjunction with 3D-light-sheet fluorescence microscopy and single cell RNA sequencing to perform a comprehensive spatiotemporal analysis of the composition, origin and differentiation of MΦ subsets within the healthy and inflamed joint and subsequently studied their roles during arthritis. This approach revealed dynamic membrane-like structures consisting of a distinct population of CX3CR1+ tissue-resident MΦs that formed an internal immunological barrier at the synovial lining and physically secluded the joint. Barrier-forming MΦs displayed features otherwise typical of epithelial cells, and maintained their numbers through a pool of locally proliferating CX3CR1- mononuclear cells embedded into the synovial tissue. Unlike recruited monocyte-derived MΦs, which actively contributed to joint inflammation, such epithelial-like CX3CR1+ lining MΦs restricted the inflammatory reaction by providing a tight junction-mediated shield for intra-articular structures. Our data thus reveal an unexpected functional diversification among synovial MΦs and have important implications for the general role of MΦs in health and disease
Project description:Macrophages (MΦs) are considered to contribute to chronic inflammatory diseases such as rheumatoid arthritis 1. However, both the exact origin and role of MΦs during inflammatory joint disease remain unclear. Here, we used multiple fate-mapping approaches in conjunction with 3D-light-sheet fluorescence microscopy and single cell RNA sequencing to perform a comprehensive spatiotemporal analysis of the composition, origin and differentiation of MΦ subsets within the healthy and inflamed joint and subsequently studied their roles during arthritis. This approach revealed dynamic membrane-like structures consisting of a distinct population of CX3CR1+ tissue-resident MΦs that formed an internal immunological barrier at the synovial lining and physically secluded the joint. Barrier-forming MΦs displayed features otherwise typical of epithelial cells, and maintained their numbers through a pool of locally proliferating CX3CR1- mononuclear cells embedded into the synovial tissue. Unlike recruited monocyte-derived MΦs, which actively contributed to joint inflammation, such epithelial-like CX3CR1+ lining MΦs restricted the inflammatory reaction by providing a tight junction-mediated shield for intra-articular structures. Our data thus reveal an unexpected functional diversification among synovial MΦs and have important implications for the general role of MΦs in health and disease.
Project description:Osteoarthritis (OA) is a degenerative joint disease characterized by progressive cartilage loss, bone remodeling, synovial inflammation, and significant joint pain, often resulting in disability. Injury to the synovial joint such as the anterior cruciate ligament (ACL) tear is the major cause of OA in young adults. Currently, there are no approved therapies available to prevent joint degeneration or rebuild articular cartilage destroyed by OA, primarily because our understanding of the cellular and molecular changes that contribute to joint damage is very limited. The synovial joint is a complex structure composed of several tissues including articular cartilage, subchondral bone, synovium, synovial fluid, and tensile tissues including tendons and ligaments. In the present study, using single-cell RNA sequencing (scRNA-seq), we examined the cellular heterogeneity in articular cartilage from mouse knee joints and determined the knee joint injury-induced early molecular changes in the chondrocytes that could contribute to OA.
Project description:We have performed a comprehensive transcriptional analysis of specific monocyte and macrophage (MM-CM-^X) subsets during an acute self-resolving inflammatory insult. Following initial induction of acute inflammation, tissue resident (Resident) MM-CM-^X are rapidly M-bM-^@M-^XclearedM-bM-^@M-^Y from the inflammatory foci, only becoming recoverable as inflammation resolves. Monocytes are recruited to the inflammatory lesion where they differentiate into MM-CM-^X. We term these monocyte-derived MM-CM-^X M-bM-^@M-^Xinflammation-associatedM-bM-^@M-^Y to distinguish them from Resident MM-CM-^X which are present throughout the inflammatory response and can renew during the resolution of inflammation by proliferation. Comparative analysis of the Mo and MM-CM-^X populations (both M-bM-^@M-^Xinflammation-associatedM-bM-^@M-^Y and Resident MM-CM-^X) identifies select genes expressed in subsets of M-bM-^@M-^Xinflammation-associatedM-bM-^@M-^Y and Resident MM-CM-^X that play important roles in the resolution of inflammation and/or for immunity, including molecules involved in antigen presentation, cell cycle and others associated with M-bM-^@M-^XimmaturityM-bM-^@M-^Y and MM-CM-^X activation. We purified monocyte and macrophage populations from the peritoneal cavity of C57BL/6 mice 4, 18, 72 and 168 hours after the induction of inflammation with intraperitoneal administration of zymosan (2x10^7 particles). We also purified tissue resident macrophages and Ly-6B+ bone marrow monocytes from naive mice as reference populations.