Role of the chondrocyte cytoskeleton in health and disease

Introduction: Articular cartilage comprises a dense extracellular matrix (ECM) of primarily collagen, proteoglycans and water interspersed with the cartilage cell- the chondrocyte. Osteoarthritis (OA) is a disease characterised by articular cartilage degradation and a change in chondrocyte phenotype. Increased or abnormal joint loading is a risk factor for OA and can regulate chondrocyte phenotype. The chondrocyte cytoskeleton comprises actin microfilaments, tubulin microtubules and vimentin intermediate filaments and has been implicated in the propagation of physical signals to the chondrocyte nucleus, termed 'mechanotransduction'. In addition, the organisation of chondrocyte cytoskeletal networks has been observed to differ in both human OA and in a rat model of OA when compared with normal chondrocytes. We hypothesise that dysregulation of cytoskeletal networks prevents normal ECM-chondrocyte signalling and promotes a catabolic phenotype as in OA. Results: When compared with normal human chondrocytes, OA chondrocytes exhibited differences in the gene expression of components of the cytoskeleton and in the spatial organisation and architecture of the cytoskeleton, both in situ and in vitro. In normal and OA human chondrocytes cultured in agarose hydrogels, disruption of each of the three main cytoskeletal elements resulted in gene expression changes in both normal and OA cells. A number of gene responses to cytoskeletal disruption were similar in normal and OA cells, such as SOX9, MMP14, TGFB1, CASP3 and PTGS2 (COX-2). Other genes responded differently to the same treatment in normal versus OA cells, including ADAMTS5, COMP, FGFR3 and NOS2A (iNOS). Cyclic compression (15% strain, 0.5 Hz) for up to 40 minutes induced cytoskeletal reorganisation in normal and OA human chondrocytes and up-regulation of p-tubulin and destrin mRNA expression. Recovery in free swelling conditions for five hours post-load showed the chondrocyte phenotype was enhanced in OA chondrocytes. Cyclic compression in the presence of cytoskeletal disruption altered the transcriptional response of the actin depolymerising proteins cofilin and destrin in normal and OA chondrocytes, and the transcriptional response of SOX9 and the actin sequestering protein thymosin p4 in OA chondrocytes. Conclusions: Changes in the cytoskeleton of OA chondrocytes are not simply a result of the altered mechanical environment in OA articular cartilage. Changes in the cytoskeleton can affect chondrocyte phenotype and the response of chondrocytes to cyclic compression, therefore the observed differences in organisation and expression could result in the altered phenotype of OA chondrocytes. Differences between the effect of cyclic compression on normal and OA human chondrocytes support the existence of different or divergent mechanotransduction pathways that are mediated in part by elements of the chondrocyte cytoskeleton.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Role of the chondrocyte cytoskeleton in health and disease

Introduction: Articular cartilage comprises a dense extracellular matrix (ECM) of primarily collagen, proteoglycans and water interspersed with the cartilage cell- the chondrocyte. Osteoarthritis (OA) is a disease characterised by articular cartilage degradation and a change in chondrocyte phenotype. Increased or abnormal joint loading is a risk factor for OA and can regulate chondrocyte phenotype. The chondrocyte cytoskeleton comprises actin microfilaments, tubulin microtubules and vimentin intermediate filaments and has been implicated in the propagation of physical signals to the chondrocyte nucleus, termed 'mechanotransduction'. In addition, the organisation of chondrocyte cytoskeletal networks has been observed to differ in both human OA and in a rat model of OA when compared with normal chondrocytes. We hypothesise that dysregulation of cytoskeletal networks prevents normal ECM-chondrocyte signalling and promotes a catabolic phenotype as in OA. Results: When compared with normal human chondrocytes, OA chondrocytes exhibited differences in the gene expression of components of the cytoskeleton and in the spatial organisation and architecture of the cytoskeleton, both in situ and in vitro. In normal and OA human chondrocytes cultured in agarose hydrogels, disruption of each of the three main cytoskeletal elements resulted in gene expression changes in both normal and OA cells. A number of gene responses to cytoskeletal disruption were similar in normal and OA cells, such as SOX9, MMP14, TGFB1, CASP3 and PTGS2 (COX-2). Other genes responded differently to the same treatment in normal versus OA cells, including ADAMTS5, COMP, FGFR3 and NOS2A (iNOS). Cyclic compression (15% strain, 0.5 Hz) for up to 40 minutes induced cytoskeletal reorganisation in normal and OA human chondrocytes and up-regulation of p-tubulin and destrin mRNA expression. Recovery in free swelling conditions for five hours post-load showed the chondrocyte phenotype was enhanced in OA chondrocytes. Cyclic compression in the presence of cytoskeletal disruption altered the transcriptional response of the actin depolymerising proteins cofilin and destrin in normal and OA chondrocytes, and the transcriptional response of SOX9 and the actin sequestering protein thymosin p4 in OA chondrocytes. Conclusions: Changes in the cytoskeleton of OA chondrocytes are not simply a result of the altered mechanical environment in OA articular cartilage. Changes in the cytoskeleton can affect chondrocyte phenotype and the response of chondrocytes to cyclic compression, therefore the observed differences in organisation and expression could result in the altered phenotype of OA chondrocytes. Differences between the effect of cyclic compression on normal and OA human chondrocytes support the existence of different or divergent mechanotransduction pathways that are mediated in part by elements of the chondrocyte cytoskeleton

Modeling the extracellular matrix in cell migration and morphogenesis:a guide for the curious biologist

The extracellular matrix (ECM) is a highly complex structure through which biochemical and mechanical signals are transmitted. In processes of cell migration, the ECM also acts as a scaffold, providing structural support to cells as well as points of potential attachment. Although the ECM is a well-studied structure, its role in many biological processes remains difficult to investigate comprehensively due to its complexity and structural variation within an organism. In tandem with experiments, mathematical models are helpful in refining and testing hypotheses, generating predictions, and exploring conditions outside the scope of experiments. Such models can be combined and calibrated with in vivo and in vitro data to identify critical cell-ECM interactions that drive developmental and homeostatic processes, or the progression of diseases. In this review, we focus on mathematical and computational models of the ECM in processes such as cell migration including cancer metastasis, and in tissue structure and morphogenesis. By highlighting the predictive power of these models, we aim to help bridge the gap between experimental and computational approaches to studying the ECM and to provide guidance on selecting an appropriate model framework to complement corresponding experimental studies

Invasive genetic rescue: dispersal following repeated culling reinforces the genetic diversity of an invasive mammal

Since its introduction from the United States in 1876, the invasive North American Eastern grey squirrel (Sciurus carolinensis) has contributed to the decline of the native Eurasian red squirrel (Sciurus vulgaris) in Britain. The aim of this study was to assess the overall impact of repeated control efforts carried out between 2011 and 2020 on the genetic diversity of the grey squirrel population in north Wales. This information can be used to inform future adaptive management plans, increasing the success of invasive species control efforts and enhancing red squirrel conservation efforts. Using a combination of mitochondrial DNA (mtDNA) and microsatellite DNA analysis, we found high genetic diversity in both marker types, with six diverse mtDNA haplotypes found and relatively high levels of nuclear genetic diversity, even after repeated culling efforts. We also found that repeated introductions from multiple locations in North America have generated a genetically diverse population in Britain today, compounding the management of this invasive species. Our results suggest that ongoing grey squirrel control efforts may not adequately reduce genetic diversity to a level where it contributes to a long-term population decline, and highlights the need to gather all available information, including historical and contemporary, to effectively create a plan for control efforts of invasive species

Supporting self-management for patients with Interstitial Lung Diseases: Utility and acceptability of digital devices

INTRODUCTION: Patients diagnosed with Interstitial Lung Diseases (ILD) use devices to self-monitor their health and well-being. Little is known about the range of devices, selection, frequency and terms of use and overall utility. We sought to quantify patients' usage and experiences with home digital devices, and further evaluate their perceived utility and barriers to adaptation. METHODS: A team of expert clinicians and patient partners interested in self-management approaches designed a 48-question cross-sectional electronic survey; specifically targeted at individuals diagnosed with ILD. The survey was critically appraised by the interdisciplinary self-management group at Royal Devon University Hospitals NHS Foundation Trust during a 6-month validation process. The survey was open for participation between September 2021 and December 2022, and responses were collected anonymously. Data were analysed descriptively for quantitative aspects and through thematic analysis for qualitative input. RESULTS: 104 patients accessed the survey and 89/104 (86%) reported a diagnosis of lung fibrosis, including 46/89 (52%) idiopathic pulmonary fibrosis (IPF) with 57/89 (64%) of participants diagnosed >3 years and 59/89 (66%) female. 52/65(80%) were in the UK; 33/65 (51%) reported severe breathlessness medical research council MRC grade 3-4 and 32/65 (49%) disclosed co-morbid arthritis or joint problems. Of these, 18/83 (22%) used a hand- held spirometer, with only 6/17 (35%) advised on how to interpret the readings. Pulse oximetry devices were the most frequently used device by 35/71 (49%) and 20/64 (31%) measured their saturations more than once daily. 29/63 (46%) of respondents reported home-monitoring brought reassurance; of these, for 25/63 (40%) a feeling of control. 10/57 (18%) felt it had a negative effect, citing fluctuating readings as causing stress and 'paranoia'. The most likely help-seeking triggers were worsening breathlessness 53/65 (82%) and low oxygen saturation 43/65 (66%). Nurse specialists were the most frequent source of help 24/63 (38%). Conclusion: Patients can learn appropriate technical skills, yet perceptions of home-monitoring are variable; targeted assessment and tailored support is likely to be beneficial

Supporting self-management for patients with Interstitial Lung Diseases:Utility and acceptability of digital devices

INTRODUCTION: Patients diagnosed with Interstitial Lung Diseases (ILD) use devices to self-monitor their health and well-being. Little is known about the range of devices, selection, frequency and terms of use and overall utility. We sought to quantify patients' usage and experiences with home digital devices, and further evaluate their perceived utility and barriers to adaptation.METHODS: A team of expert clinicians and patient partners interested in self-management approaches designed a 48-question cross-sectional electronic survey; specifically targeted at individuals diagnosed with ILD. The survey was critically appraised by the interdisciplinary self-management group at Royal Devon University Hospitals NHS Foundation Trust during a 6-month validation process. The survey was open for participation between September 2021 and December 2022, and responses were collected anonymously. Data were analysed descriptively for quantitative aspects and through thematic analysis for qualitative input.RESULTS: 104 patients accessed the survey and 89/104 (86%) reported a diagnosis of lung fibrosis, including 46/89 (52%) idiopathic pulmonary fibrosis (IPF) with 57/89 (64%) of participants diagnosed &gt;3 years and 59/89 (66%) female. 52/65(80%) were in the UK; 33/65 (51%) reported severe breathlessness medical research council MRC grade 3-4 and 32/65 (49%) disclosed co-morbid arthritis or joint problems. Of these, 18/83 (22%) used a hand- held spirometer, with only 6/17 (35%) advised on how to interpret the readings. Pulse oximetry devices were the most frequently used device by 35/71 (49%) and 20/64 (31%) measured their saturations more than once daily. 29/63 (46%) of respondents reported home-monitoring brought reassurance; of these, for 25/63 (40%) a feeling of control. 10/57 (18%) felt it had a negative effect, citing fluctuating readings as causing stress and 'paranoia'. The most likely help-seeking triggers were worsening breathlessness 53/65 (82%) and low oxygen saturation 43/65 (66%). Nurse specialists were the most frequent source of help 24/63 (38%). Conclusion: Patients can learn appropriate technical skills, yet perceptions of home-monitoring are variable; targeted assessment and tailored support is likely to be beneficial.</p

Active children through incentive vouchers – evaluation (ACTIVE): a mixed-method feasibility study

BackgroundAdolescents face many barriers to physical activity, demonstrated by the decline in physical activity levels in teenage populations. This study aimed to assess the feasibility of overcoming such barriers via the implementation of an activity-promoting voucher scheme to teenagers in deprived areas.MethodsAll Year 9 pupils (n = 115; 13.3 ± 0.48 years; 51 % boys) from one secondary school in Wales (UK) participated. Participants received £25 of activity vouchers every month for six months for physical activity or sporting equipment. Focus groups (n = 7), with 43 pupils, and qualitative interviews with teachers (n = 2) were conducted to assess feasibility, in addition to a process evaluation utilising the RE-AIM framework. Quantitative outcomes at baseline, five months (during intervention) and twelve months (follow-up) included: physical activity (accelerometer), aerobic fitness (12 min Cooper run) and self-reported activity (PAQ-A). Motivation to exercise (BREQ-2) was measured three months post-baseline and at follow-up.ResultsQualitative findings showed that vouchers encouraged friends to socialise through activity, provided opportunities to access local activities that pupils normally could not afford, and engaged both those interested and disinterested in physical education. Improvements in weekend moderate-to-vigorous physical activity and reductions in sedentary behaviour were observed in both sexes. Boys’ fitness significantly improved during the voucher scheme. ‘Non-active’ pupils (those not meeting recommended guidelines of 60 mins∙day−1) and those with higher motivation to exercise had higher voucher use.ConclusionsAdolescents, teachers and activity providers supported the voucher scheme and felt the vouchers enabled deprived adolescents to access more physical activity opportunities. Voucher usage was associated with improved attitudes to physical activity, increased socialisation with friends and improved fitness and physical activity; presenting interesting avenues for further exploration in a larger intervention trial

Deconstructing compassionate conservation

Compassionate conservation focuses on 4 tenets: first, do no harm; individuals matter; inclusivity of individual animals; and peaceful coexistence between humans and animals. Recently, compassionate conservation has been promoted as an alternative to conventional conservation philosophy. We believe examples presented by compassionate conservationists are deliberately or arbitrarily chosen to focus on mammals; inherently not compassionate; and offer ineffective conservation solutions. Compassionate conservation arbitrarily focuses on charismatic species, notably large predators and megaherbivores. The philosophy is not compassionate when it leaves invasive predators in the environment to cause harm to vastly more individuals of native species or uses the fear of harm by apex predators to terrorize mesopredators. Hindering the control of exotic species (megafauna, predators) in situ will not improve the conservation condition of the majority of biodiversity. The positions taken by so-called compassionate conservationists on particular species and on conservation actions could be extended to hinder other forms of conservation, including translocations, conservation fencing, and fertility control. Animal welfare is incredibly important to conservation, but ironically compassionate conservation does not offer the best welfare outcomes to animals and is often ineffective in achieving conservation goals. Consequently, compassionate conservation may threaten public and governmental support for conservation because of the limited understanding of conservation problems by the general public

Ten-year mortality, disease progression, and treatment-related side effects in men with localised prostate cancer from the ProtecT randomised controlled trial according to treatment received

Background The ProtecT trial reported intention-to-treat analysis of men with localised prostate cancer randomly allocated to active monitoring (AM), radical prostatectomy, and external beam radiotherapy. Objective To report outcomes according to treatment received in men in randomised and treatment choice cohorts. Design, setting, and participants This study focuses on secondary care. Men with clinically localised prostate cancer at one of nine UK centres were invited to participate in the treatment trial comparing AM, radical prostatectomy, and radiotherapy. Intervention Two cohorts included 1643 men who agreed to be randomised and 997 who declined randomisation and chose treatment. Outcome measurements and statistical analysis Analysis was carried out to assess mortality, metastasis and progression and health-related quality of life impacts on urinary, bowel, and sexual function using patient-reported outcome measures. Analysis was based on comparisons between groups defined by treatment received for both randomised and treatment choice cohorts in turn, with pooled estimates of intervention effect obtained using meta-analysis. Differences were estimated with adjustment for known prognostic factors using propensity scores. Results and limitations According to treatment received, more men receiving AM died of PCa (AM 1.85%, surgery 0.67%, radiotherapy 0.73%), whilst this difference remained consistent with chance in the randomised cohort (p = 0.08); stronger evidence was found in the exploratory analyses (randomised plus choice cohort) when AM was compared with the combined radical treatment group (p = 0.003). There was also strong evidence that metastasis (AM 5.6%, surgery 2.4%, radiotherapy 2.7%) and disease progression (AM 20.35%, surgery 5.87%, radiotherapy 6.62%) were more common in the AM group. Compared with AM, there were higher risks of sexual dysfunction (95% at 6 mo) and urinary incontinence (55% at 6 mo) after surgery, and of sexual dysfunction (88% at 6 mo) and bowel dysfunction (5% at 6 mo) after radiotherapy. The key limitations are the potential for bias when comparing groups defined by treatment received and changes in the protocol for AM during the lengthy follow-up required in trials of screen-detected PCa. Conclusions Analyses according to treatment received showed increased rates of disease-related events and lower rates of patient-reported harms in men managed by AM compared with men managed by radical treatment, and stronger evidence of greater PCa mortality in the AM group. Patient summary More than 95 out of every 100 men with low or intermediate risk localised prostate cancer do not die of prostate cancer within 10 yr, irrespective of whether treatment is by means of monitoring, surgery, or radiotherapy. Side effects on sexual and bladder function are better after active monitoring, but the risks of spreading of prostate cancer are more common