Biology subjects

Vincent, T. L.

Publications and source records attributed to Vincent, T. L..

5 recordsLinked to original sources

bioRxiv2021

Variants in ALDH1A2 reveal an anti-inflammatory role for retinoic acid and a new class of disease-modifying drugs in osteoarthritis

Over 40% of individuals will develop osteoarthritis (OA) during their lifetime, yet there are currently no licensed disease modifying treatments for this disabling condition. Common polymorphic variants in ALDH1A2, that encodes the key enzyme in the synthesis of all-trans retinoic acid (atRA), have been associated with severe hand OA. In this study, we sought to elucidate the biological significance of this association. We first confirmed that ALDH1A2 risk variants were associated with hand OA in UK Biobank. Articular cartilage was acquired from 33 consenting individuals with hand OA at the time of routine hand OA surgery. They were stratified by genotype and RNA sequencing performed. A reciprocal relationship between ALDH1A2 mRNA and inflammatory genes was observed. Articular cartilage injury up-regulates similar inflammatory genes by a process that we have previously termed mechanoflammation, and which we believe is a primary driver of OA. Cartilage injury was also associated with a concomitant drop in atRA-dependent genes, indicative of cellular atRA levels, and both responses to injury were reversed using talarozole, a retinoic acid metabolism blocking agent (RAMBA). Suppression of mechanoflammation by talarozole was mediated by a peroxisome proliferator activated receptor (PPAR)-{gamma} dependent mechanism. Talarozole, delivered by minipump, was able to suppress mechano-inflammatory genes in articular cartilage in vivo 6h after mouse knee joint destabilization, and reduced cartilage degradation and osteophyte formation after 4 weeks. These data show that boosting atRA suppresses mechanoflammation in the articular cartilage in vitro and in vivo, and identifies RAMBAs as potential disease modifying drugs in OA. One Sentence SummaryAnalysis of hand OA cartilage stratified by ALDH1A2 polymorphic variants reveals a targetable, anti-inflammatory role for retinoic acid in OA.

molecular biology↗

bioRxiv2021

Ciliary IFT88 safeguards coordinated epiphyseal vascularisation, resorption and ossification from disruptive physiological mechanical forces

In the musculoskeletal system, appropriate cell and tissue responses to mechanical force delineate morphogenesis and ensure lifelong health. Despite this, how mechanical cues are integrated into biological programmes remains unclear. Primary cilia are microtubule-based organelles that tune a range of cell activities, including signalling cascades activated or modulated, by extracellular biophysical cues. Here, we demonstrate that the inducible, cartilage-specific deletion of Intraflagellar transport protein 88 (IFT88), which reduces ciliation in the adolescent mouse growth plate (GP), uncouples chondrocyte differentiation from cartilage resorption and mineralisation in a mechano-dependent manner. Targeting IFT88, inhibits hypertrophic chondrocyte VEGF expression, vascular recruitment, osteoclastic activity and the replacement of cartilage with bone. These effects are largely restricted to peripheral tibial regions beneath the load-bearing compartments of the knee. Increases in physiological loading, in control mice, also impairs ossification in the peripheral GP, mimicking the effects of IFT88 deletion. Strikingly, limb immobilisation rescues disrupted VEGF and restores epiphyseal dynamics in Ift88cKO mice. These data indicate, that during this pivotal phase in adolescent skeletal maturation that defines the cessation of growth, ciliary IFT88 protects the coordinated ossification of the growth plate from an otherwise disruptive heterogeneity of physiological mechanical forces.

physiology↗

bioRxiv2021

Matrix-Bound Growth Factors are Released upon Cartilage Compression by an Aggrecan-Dependent Sodium Flux that is Lost in Osteoarthritis

Articular cartilage is a dense extracellular matrix-rich tissue that degrades following chronic mechanical stress, resulting in osteoarthritis (OA). The tissue has low intrinsic repair especially in aged and osteoarthritic joints. Here we describe three pro-regenerative factors; fibroblast growth factor 2 (FGF2), connective tissue growth factor, bound to transforming growth factor-beta (CTGF-TGF{beta}), and hepatoma-derived growth factor (HDGF), that are rapidly released from the pericellular matrix (PCM) of articular cartilage upon mechanical injury. All three growth factors bound heparan sulfate, and were displaced by exogenous NaCl. We hypothesised that sodium, sequestered within the aggrecan-rich matrix, was freed by injurious compression, thereby enhancing the bioavailability of pericellular growth factors. Indeed, growth factor release was abrogated when cartilage aggrecan was depleted by IL-1 treatment, and in severely damaged human osteoarthritic cartilage. A flux in free matrix sodium upon mechanical compression of cartilage was visualised by 23Na magnetic resonance imaging (MRI) just below the articular surface. This corresponded to a region of reduced tissue stiffness, measured by scanning acoustic microscopy and second harmonic generation microscopy, and where Smad2/3 was phosphorylated upon cyclic compression. Our results describe a novel intrinsic repair mechanism, controlled by matrix stiffness and mediated by the free sodium concentration, in which heparan sulfate-bound growth factors are released from cartilage upon injurious load. They identify aggrecan as a depot for sequestered sodium, explaining why osteoarthritic tissue loses its ability to repair. Treatments that restore matrix sodium to allow appropriate release of growth factors upon load are predicted to enable intrinsic cartilage repair in osteoarthritis. Significance StatementOsteoarthritis is the most prevalent musculoskeletal disease, affecting 250 million people worldwide 1. We identify a novel intrinsic repair response in cartilage, mediated by aggrecan-dependent sodium flux, and dependent upon matrix stiffness, which results in the release of a cocktail of pro-regenerative growth factors after injury. Loss of aggrecan in late-stage osteoarthritis prevents growth factor release and likely contributes to disease progression. Treatments that restore matrix sodium in osteoarthritis may recover the intrinsic repair response to improve disease outcome.

cell biology↗

bioRxiv2021

Age-dependent changes in protein incorporation into collagen-rich tissues of mice by in vivo pulsed SILAC labelling

Collagen-rich tissues have poor reparative capacity that is further impaired with age, predisposing to common age-related disorders such as osteoporosis and osteoarthritis. We used in vivo pulsed SILAC labelling to quantify new protein incorporation into cartilage, bone, skin and plasma of mice across the life course. We report highly dynamic matrisome turnover in bone and cartilage during skeletal maturation, which was markedly reduced after skeletal maturity. Comparing young adult with older adult mice, new protein incorporation was reduced in all tissues. STRING clustering revealed epigenetic modulation across all tissues, a decline in chondroprotective growth factors such as FGF2 and TGFb in cartilage, and clusters indicating mitochondrial dysregulation and reduced collagen synthesis in bone. Several of these pathways have been associated with age-related disease. Fewer changes were observed for skin and plasma. This methodology provides dynamic protein data at a tissue level, uncovering age-related molecular changes that may predispose to disease.

developmental biology↗

bioRxiv2020

The ciliary protein IFT88 controls post-natal cartilage thickness and influences development of osteoarthritis.

Mechanical and biological cues drive cellular signalling in cartilage development, health, and disease. Proteins of the primary cilium, implicated in transduction of biophysiochemical signals, control cartilage formation during skeletal development, but their influence in post-natal cartilage remains unknown. Ift88fl/fl and AggrecanCreERT2 mice were crossed to create a cartilage-specific, inducible knockout mouse AggrecanCreERT2;Ift88fl/fl. Tibial articular cartilage (AC) thickness was assessed, through adolescence and adulthood, by histomorphometry and integrity by OARSI score. In situ mechanisms were investigated by immunohistochemistry (IHC), RNA scope and qPCR of micro-dissected cartilage. OA was induced by surgical destabilisation (DMM). Mice voluntarily exercised using wheels. Deletion of IFT88 resulted in progressive reductions in medial AC thickness during adolescence, and marked atrophy in adulthood. At 34 weeks of age, medial thickness was reduced from 104.00m, [100.30-110.50, 95% CI] in Ift88fl/fl to 89.42m [84.00-93.49, 95% CI] in AggrecanCreERT2;Ift88fl/fl (p<0.0001), associated with reductions in calcified cartilage. Occasionally, atrophy was associated with complete, spontaneous, medial cartilage degradation. Following DMM, AggrecanCreERT2;Ift88fl/fl mice had increased OA scores. Atrophy in mature AC was not associated with obvious increases in aggrecanase-mediated destruction or chondrocyte hypertrophy. Ift88 expression positively correlated with Tcf7l2, connective tissue growth factor (Ctgf) and Enpp1. RNA scope revealed increased hedgehog (Hh) signalling (Gli1), associated with reductions in Ift88, in AggrecanCreERT2;Ift88fl/fl cartilage. Wheel exercise restored both AC thickness and levels of Hh signalling in AggrecanCreERT2;Ift88fl/fl. Our results demonstrate that IFT88 is chondroprotective, regulating AC thickness, potentially by thresholding a Hh response to physiological loading that controls cartilage calcification.

molecular biology↗