Novel biomarkers for arthritis: The role of P2X7 receptor in transglutaminase 2 export and activation

Transglutaminase 2 (TG2)-mediated stabilization of extracellular protein assemblies has a pivotal function in tissue repair. However, aberrant TG2 activity has been linked to fibrosis and autoimmunity. There is also evidence that post-translational modification of proteins can occur in a manner that is specific to disease, for example citrullinated peptides seen in rheumatoid arthritis. TG2 modifies proteins in several ways, including through transamidation, esterification and deamidation of target glutamine residues. There is evidence of increased expression and activity of TG2 in osteoarthritis, potentially leading to the generation of protein modifications, which could act as biological markers of disease. The mechanism of TG2 release by cells controls its extracellular activity is unconventional and enigmatic. Our group has shown that TG2 export is linked to purinergic signalling, and implicated P2X7 receptor activation. P2X7R has several activation states; ATP stimulation causes ion channel opening,allowing membrane depolarization and Ca2+ entry into the cell. Prolonged stimulation leads to ‘large membrane pore’ activity, however the identity of this pore is unknown as there is conflicting evidence suggesting either dilation of the P2X7R channel itself or an interaction with an alternative plasma membrane channel. The aim of this thesis is to elucidate mechanistically the process by which cells export TG2 and control its activation, alongside investigating the P2X7R pore. We have also looked at the involvement of GTP regulation of TG2 activity in its secretion and whether the TG2 activator, thioredoxin, can be secreted via the same pathway. Through the use of pharmacological agents, we have shown that pannexin-1, a plasma membrane hemichannel proposed to interact with P2X7R, is unlikely to be the pore-forming component of P2X7R activation. A gain of function mutation in P2X7R expressed in HEK293 cells shows enhanced TG2 externalization from cells, correlating with increased pore activity,implicating P2X7R itself. Thioredoxin, a TG2 activator, is co-secreted. To confirm the transferability of our findings in this cell model to the innate immune response, human peripheral blood monocytes were differentiated into M1 macrophages and P2X7R mediated TG2 export assessed. Investigating this process will unravel a novel secretory pathway potentially used by select proteins, including potent signals regulating inflammation

Enriched functor categories for functor calculus

In this paper we present background results in enriched category theory and enriched model category theory necessary for developing model categories of enriched functors suitable for doing functor calculus.Comment: 31 pages. Comments welcom

Cofibrantly generated model structures for functor calculus

Model structures for many different kinds of functor calculus can be obtained by applying a theorem of Bousfield to a suitable category of functors. In this paper, we give a general criterion for when model categories obtained via this approach are cofibrantly generated. Our examples recover the homotopy functor and $n$-excisive model structures of Biedermann and R\"ondigs, with different proofs, but also include a model structure for the discrete functor calculus of Bauer, Johnson, and McCarthy.Comment: 52 pages. Comments welcome

Direct and indirect effects of the COVID-19 pandemic on mortality: an individual-level population-scale analysis.

Objectives The COVID-19 pandemic has had a detrimental impact on healthcare utilisation, resulting in increased mortality both directly and indirectly associated with COVID-19. We aimed to assess the impact of the COVID-19 pandemic on all-cause and disease-specific mortality and further explore the impact of potential inequalities, deprivation status and ethnicity. Approach Population-scale, individual-level, anonymised linked, routinely-collected electronic health records from demographic and administrative sources were used for two cohorts: i) C19-COHORT16 included individuals alive and resident in Wales on the 1st January 2016 with follow-up until death, break-in Welsh residency, or 31st December 2019; ii) C19-COHORT20 included individuals alive and resident in Wales on 1st January 2020 with follow-up until death, break-in Welsh residency, or study end. We used time-series analysis to investigate trends in mortality over time. We fitted negative binomial models to estimate expected all-cause and disease-specific mortality and compared these estimates to observed mortality in C19-COHORT20. Results Excess all-cause and COVID19-related deaths were higher during the period where the alpha variant was dominant. The trend in deaths decreased during the omicron dominant period. The Asian population had increased mortality during the period where the delta variant was dominant. Mortality was increased for most deprived groups compared to least deprived groups, however, the magnitude of this effect remained unchanged during the pandemic. COVID-19 indirectly affected cancer, circulatory, trauma, digestive and mental health related deaths, with a higher than expected mortality. The majority of trauma related deaths occurred early on in the pandemic, where a higher than expected number of deaths occurred outside of an NHS establishment. Mortality associated with respiratory disease (unrelated to COVID-19) was significantly lower than expected during the COVID-19 pandemic. Conclusion Increased all-cause and disease-specific mortality was observed during the COVID-19 pandemic. Excess deaths may be a result of reduced healthcare utilisation, delayed investigation and/or treatment of chronic diseases. As healthcare systems recover from COVID-19, investigation of mortality trends will play a central role in healthcare planning, utilisation and resource use

Uptake of COVID-19 vaccinations amongst 3,433,483 children and young people: meta-analysis of UK prospective cohorts

SARS-CoV-2 infection in children and young people (CYP) can lead to life-threatening COVID-19, transmission within households and schools, and the development of long COVID. Using linked health and administrative data, we investigated vaccine uptake among 3,433,483 CYP aged 5–17 years across all UK nations between 4th August 2021 and 31st May 2022. We constructed national cohorts and undertook multi-state modelling and meta-analysis to identify associations between demographic variables and vaccine uptake. We found that uptake of the first COVID-19 vaccine among CYP was low across all four nations compared to other age groups and diminished with subsequent doses. Age and vaccination status of adults living in the same household were identified as important risk factors associated with vaccine uptake in CYP. For example, 5–11 year-olds were less likely to receive their first vaccine compared to 16–17 year-olds (adjusted Hazard Ratio [aHR]: 0.10 (95%CI: 0.06–0.19)), and CYP in unvaccinated households were less likely to receive their first vaccine compared to CYP in partially vaccinated households (aHR: 0.19, 95%CI 0.13–0.29)

Trajectories in chronic disease accrual and mortality across the lifespan in Wales, UK (2005–2019), by area deprivation profile: linked electronic health records cohort study on 965,905 individuals

Background: Understanding and quantifying the differences in disease development in different socioeconomic groups of people across the lifespan is important for planning healthcare and preventive services. The study aimed to measure chronic disease accrual, and examine the differences in time to individual morbidities, multimorbidity, and mortality between socioeconomic groups in Wales, UK.Methods: Population-wide electronic linked cohort study, following Welsh residents for up to 20 years (2000-2019). Chronic disease diagnoses were obtained from general practice and hospitalisation records using the CALIBER disease phenotype register. Multi-state models were used to examine trajectories of accrual of 132 diseases and mortality, adjusted for sex, age and area-level deprivation. Restricted mean survival time was calculated to measure time spent free of chronic disease(s) or mortality between socioeconomic groups.Findings: In total, 965,905 individuals aged 5-104 were included, from a possible 2.9 m individuals following a 5-year clearance period, with an average follow-up of 13.2 years (12.7 million person-years). Some 673,189 (69.7%) individuals developed at least one chronic disease or died within the study period. From ages 10 years upwards, the individuals living in the most deprived areas consistently experienced reduced time between health states, demonstrating accelerated transitions to first and subsequent morbidities and death compared to their demographic equivalent living in the least deprived areas. The largest difference were observed in 10 and 20 year old males developing multimorbidity (-0.45 years (99% CI: -0.45, -0.44)) and in 70 year old males dying after developing multimorbidity (-1.98 years (99% CI: -2.01, -1.95)).Interpretation: This study adds to the existing literature on health inequalities by demonstrating that individuals living in more deprived areas consistently experience accelerated time to diagnosis of chronic disease and death across all ages, accounting for competing risks

P2X7 receptor activation regulates rapid unconventional export of transglutaminase-2

Transglutaminases (TG) are externalized from cells via an unknown unconventional secretory pathway. We show for the first time that purinergic signaling regulates active secretion of TG2, an enzyme with a pivotal role in stabilizing extracellular matrices and modulating cell-matrix interactions in tissue repair. Extracellular ATP promotes TG2 secretion by macrophages, and this can be blocked by a purinergic receptor P2X7 (P2X7R)-selective antagonist. Introduction of functional P2X7R into HEK293 cells is sufficient to confer rapid, regulated TG2 export. By employing pharmacological agents, TG2 release could be separated from P2X7R-mediated microvesicle shedding. Neither, Ca2+ signaling alone nor membrane depolarization triggered TG2 secretion which occurred only upon receptor membrane pore formation and without pannexin channel involvement. A gain-of-function mutation in P2X7R associated with autoimmune disease caused enhanced TG2 externalization from cells, and this correlated with increased pore activity. These results provide a mechanistic explanation for a link between active TG2 secretion and inflammatory responses, and aberrant enhanced TG2 activity in certain autoimmune conditions

Risk of thrombocytopenic, haemorrhagic and thromboembolic disorders following COVID-19 vaccination and positive test: a self-controlled case series analysis in Wales

There is a need for better understanding of the risk of thrombocytopenic, haemorrhagic, thromboembolic disorders following first, second and booster vaccination doses and testing positive for SARS-CoV-2. Self-controlled cases series analysis of 2.1 million linked patient records in Wales between 7th December 2020 and 31st December 2021. Outcomes were the first diagnosis of thrombocytopenic, haemorrhagic and thromboembolic events in primary or secondary care datasets, exposure was defined as 0–28 days post-vaccination or a positive reverse transcription polymerase chain reaction test for SARS-CoV-2. 36,136 individuals experienced either a thrombocytopenic, haemorrhagic or thromboembolic event during the study period. Relative to baseline, our observations show greater risk of outcomes in the periods post-first dose of BNT162b2 for haemorrhagic (IRR 1.47, 95%CI: 1.04–2.08) and idiopathic thrombocytopenic purpura (IRR 2.80, 95%CI: 1.21–6.49) events; post-second dose of ChAdOx1 for arterial thrombosis (IRR 1.14, 95%CI: 1.01–1.29); post-booster greater risk of venous thromboembolic (VTE) (IRR-Moderna 3.62, 95%CI: 0.99–13.17) (IRR-BNT162b2 1.39, 95%CI: 1.04–1.87) and arterial thrombosis (IRR-Moderna 3.14, 95%CI: 1.14–8.64) (IRR-BNT162b2 1.34, 95%CI: 1.15–1.58). Similarly, post SARS-CoV-2 infection the risk was increased for haemorrhagic (IRR 1.49, 95%CI: 1.15–1.92), VTE (IRR 5.63, 95%CI: 4.91, 6.4), arterial thrombosis (IRR 2.46, 95%CI: 2.22–2.71). We found that there was a measurable risk of thrombocytopenic, haemorrhagic, thromboembolic events after COVID-19 vaccination and infection

Lived experience researchers partnering with consumers and carers to improve mental health research: Reflections from an Australian initiative

Consumer and carer involvement in mental health research is a growing and developing field. Whilst there has been policy and in-principle support for such involvement from governments around the world, lived experience researchers conducting academic research in partnership with other consumers and carers remains uncommon. ACACIA: The Australian Capital Territory Consumer and Carer Mental Health Research Unit is based at The Australian National University and employs academic researchers with lived experience to undertake research directly relevant to the needs of mental health consumers and carers with the aim of influencing policy and practice. In this study, we share our experience of developing and conducting research within ACACIA to provide a model for meaningfully engaging mental health consumers and carers throughout the research process.This research was supported by ACT Health (Contracts 2013.21920.590 to KG and 2015.275404.340 to MB). At the time of undertaking the research, MB was supported by Australian Research Council Discovery Early Career Researcher Award DE150100637 and KG was supported by National Health and Medical Research Council Senior Research Fellowship 1059620