FcgammaRIIb: Signalling aspects and implications for autoimmune disease

Fc receptors (FcRs) provide a critical link between the humoral and cellular arms of the immune system through the targeting of antigen-antibody complexes to effector cells and modulation of an immune response. B cells express a low affinity IgG Fc receptor, FcgammaRIIb, which negatively regulates antigen receptor-mediated proliferative signalling through the binding of IgG- containing immune complexes. Co-ligation of the B cell antigen receptor (BCR) complex with FcyRIIb promotes the induction of B cell growth arrest in the G1 phase of the cell cycle and this ultimately results in commitment to apoptosis. Furthermore, FcgammaRIIb co-ligation also acts as an important negative feedback mechanism to switch off ongoing B cell responses once the pathogen has been cleared. Thus, on resting B cells, FcgammaRIIb acts to prevent aberrant B cell activation by immune complexes and suppresses the potential induction of autoimmunity. It was therefore the aim of this study to identify and characterise the key signalling pathways responsible for FcgammaRIIb-mediated negative regulation of BCR-mediated proliferation. During the course of this study, it emerged that in normal splenic B cells, FcgammaRIIb signalling appears to act by modulating the BCR signalling threshold, via the rapid recruitment and phosphorylation of a variety of phosphatases that ultimately result in the uncoupling of the BCR from MAPKinase activation. We have corroborated these published findings that the tyrosine kinases SHP-1 and SHP-2 and the inositol 5'-phosphatase, SHIP-1, are recruited during FcgammaRIIb signalling and we have extended these studies in that we have generated novel data regarding their mechanism of action. We now also show that FcgammaRIIb co-ligation, in addition to preventing the initiation of MAPKinase signalling, induces the rapid recruitment and activation of the MAPKinase phosphatase, Pac-1, resulting in the abrogation of ongoing ErkMAPK signalling. Furthermore, we show for the first time that FcgammaRIIb coligation results in the activation of the inositol 3'-phosphatase, PTEN, with kinetics which suggest that recruitment of this tumour suppressor element antagonises BCR-coupiing to the PI-3-K/Akt pathway and hence abrogates pro survival mechanisms in B cells. Taken together, this dual pronged mechanism of FcgammaRIIb-mediated abrogation of the ErkMAPKinase and Akt pathways provides a molecular rationale for the biological consequences of BCR-FcgammaRIIb co-ligation, namely commitment to growth arrest and apoptosis. Finally, analysis of potential downstream molecular targets of ErkMAPKinase and Akt revealed that FcgammaRIIb-signalling not only inhibits the phosphorylation and activation of the tumour suppressor protein, retinoblastoma (Rb), but also induces the phosphorylation and activation of the pro-apoptotic tumour suppressor protein, p53 and disruption of mitochondrial potential. Inhibition of Rb activation and consequent induction of genes required for the transition to S phase, is consistent with the observed FcgammaRIIb-mediated arrest in the G1 phase of the cell cycle. Similarly induction of p53 and collapse of mitochondrial integrity provide insight into the effector mechanisms underlying FcgammaRIIb-driven commitment to B cell apoptosis.To maintain homeostasis and tolerance to self-antigens, B cells require a balance of signals via activatory and inhibitory co-receptors. Thus, aberrant signalling through FcgammaRIIb during B cell development could lead to the induction of autoimmunity and/or promote the progression of certain autoimmune diseases. Consistent with this, recently published studies in FcgammaRIIb-deficient mice suggested that this lesion could result in collagen-induced arthritis (CIA) in normally resistant strains of mice. (Abstract shortened by ProQuest.)

Circulating levels of anti-angiogenic VEGF-A isoform (VEGF-Axxxb) in colorectal cancer patients predicts tumour VEGF-A ratios

Purpose: Bevacizumab as an adjunct to chemotherapy improves survival for some patients with metastatic colorectal cancer. Immunohistochemical staining of samples from the registration ECOG E3200 trial of bevacizumab with FOLFOX demonstrated that only patients with carcinomas expressing low levels of VEGF-A(165)b, an anti-angiogenic splice variant of the Vascular Endothelial Growth Factor family of proteins, benefited from bevacizumab treatment. To identify a more useful biomarker of response we tested the hypothesis that circulating VEGF-A(165)b levels correlate with immunohistochemical staining. Experimental Design: 17 patients with biopsy proven colorectal adenocarcinoma had pre-operative blood samples drawn. They underwent resection and had post-resection blood drawn. The plasma was analysed for levels of VEGF-A(xxx)b using enzyme-linked immunosorbent assay (ELISA) and the tumour blocks stained for VEGF-A(xxx)b and pan-VEGF-A. The normalised ratio of VEGF-A(xxx)b expression to that of panVEGF-A expression scored by IHC was calculated and correlated with plasma VEGF-A(165)b levels. Results: Plasma levels of VEGF-A(xxx)b significantly correlated with the VEGF-A(xxx)b:panVEGF-A ratio (r=0.594, P<0.02) in colorectal cancers. Median plasma VEGF-A(xxx)b levels were 151 pg/ml. The mean (1.5±0.17) and median, IQR (1.8, 1-2) IHC scores of the patients with greater than median plasma VEGF-A(xxx)b were significantly greater than those with less than median plasma VEGF-A(xxx)b levels (mean ± SEM=0.85±10.12, median, IQR=1, 0.54-1). Conclusion: These results suggest that plasma VEGF-A(xxx)b levels could be an effective biomarker of response to Bevacizumab. These results indicate that a prospective trial is warranted to explore the use of plasma VEGF-A(xxx)b levels to stratify patients for colorectal cancer treatment by bevacizumab

DBA2J db/db mice are susceptible to early albuminuria and glomerulosclerosis that correlates with systemic insulin resistance

Diabetic nephropathy (DN) is the leading cause of kidney failure in the world. To understand important mechanisms underlying this condition, and to develop new therapies, good animal models are required. In mouse models of type 1 diabetes, the DBA/2J strain has been shown to be more susceptible to develop kidney disease than other common strains. We hypothesized this would also be the case in type 2 diabetes. We studied db/db and wild-type (wt) DBA/2J mice and compared these with the db/db BLKS/J mouse, which is currently the most widely used type 2 DN model. Mice were analyzed from age 6 to 12 wk for systemic insulin resistance, albuminuria, and glomerular histopathological and ultrastructural changes. Body weight and nonfasted blood glucose were increased by 8 wk in both genders, while systemic insulin resistance commenced by 6 wk in female and 8 wk in male db/db DBA/2J mice. The urinary albumin-to-creatinine ratio (ACR) was closely linked to systemic insulin resistance in both sexes and was increased ~50-fold by 12 wk of age in the db/db DBA/2J cohort. Glomerulosclerosis, foot process effacement, and glomerular basement membrane thickening were observed at 12 wk of age in db/db DBA/2J mice. Compared with db/db BLKS/J mice, db/db DBA/2J mice had significantly increased levels of urinary ACR, but similar glomerular histopathological and ultrastructural changes. The db/db DBA/2J mouse is a robust model of early-stage albuminuric DN, and its levels of albuminuria correlate closely with systemic insulin resistance. This mouse model will be helpful in defining early mechanisms of DN and ultimately the development of novel therapies. </jats:p

Modelling the spread and control of African swine fever in domestic and feral pigs

African swine fever (ASF) represents a significant threat to the Australian pork sector and the economy in general. Estimates of the economic damages from a large multi-state outbreak of ASF in Australia exceed $A2 billion. ASF outbreaks are widespread and increasing in number in Asia and Europe. Although ASF is not present in Australia, detections of ASF viral fragments in undeclared pork products intercepted at the Australian border and the recent spread of the disease to neighbouring Papua New Guinea demonstrate the significance of the threat. The AADIS model (Bradhurst et al., 2015), simulates the spread and control of contagious emergency animal diseases such as foot-and-mouth disease. The ability to evaluate different outbreak scenarios in time and space, and trial various control measures, assists the development of animal health policy. This project expanded the AADIS modelling framework to simulate the potential spread and control of ASF in Queensland domestic and feral pig populations. Of particular interest was the epidemiological interface between domestic and feral pigs and the potential role of ASF-infectious feral pig carcasses in transmission. The upgraded model will provide a useful decision support tool to assist with preparedness and planning for ASF outbreaks. The report provides a literature review on ASF, feral pigs in Australia, and ASF decision support tools. Case studies on the spread and control of ASF in domestic and feral pigs demonstrate the functionality of the new model. Queensland was selected as the test case study area due to the wide distribution and high numbers of feral pigs and the availability of local expertise and data from Biosecurity Queensland, Department of Agriculture and Fisheries, Australian Pork Limited and SunPork Group Pty Ltd. The model was parameterised from the literature review and expert opinion that incorporated local knowledge of Australian production systems and environmental conditions. Note that the model is only parameterised for Queensland and will be scaled up to a national model through Biosecurity Innovation Program project 182021

MiniMovers: An Initial Pilot and Feasibility Study to Investigate the Impact of a Mobile Application on Children’s Motor Skills and Parent Support for Physical Development

The MiniMovers (MM) APP combines motor development theory with creativity expertise and has been designed to provide parents with developmentally appropriate activities to support children’s motor skills. This study investigates how MiniMovers activities enabled parents to suppport their children’s physical development. Families participated in an 8-week MM programme of activities from the MM APP (Mini, Mighty and Mega levels), with pre- and post-intervention data collected using multiple tools (e.g., motion capture system, force plate, eye-tracking glasses, and videos). Mixed research methods were applied among children (N = 8; aged 21–79 months) and their parents, providing quantitative analysis on children’s performance (running, throwing, jumping, kicking, balancing and catching), as well as qualitative analysis on parents’ attitude and behaviour (two-weekly feedback surveys and interviews). Lab-based measures showed significant improvements in run time, underarm throwing distance, and horizontal jump distance. Test of Gross Motor Development-3 showed a significant gain in running, underarm and overarm throwing, horizontal jump and kicking. Further, developmental stages indicated significant improvements in running, kicking and catching. Parents reported increased enjoyment and knowledge, children’s enjoyment, independence and confidence. This pilot study provides support for the research and development of the MM App and suggests more research into the use of APPs to support home activities among families with young children

Effects of the pattern of glucocorticoid replacement on neural processing, emotional reactivity and well-being in healthy male individuals:study protocol for a randomised controlled trial

BACKGROUND: Deviation from the physiological glucocorticoid dynamics (circadian and underlying ultradian rhythmicity) is a common characteristic of various neuropsychiatric and endocrine disorders as well as glucocorticoid-based therapeutics. These states may be accompanied by neuropsychiatric symptomatology, suggesting continuous dynamic glucocorticoid equilibrium is essential for brain homeostasis. METHODS/DESIGN: The study consists of two parts. The preliminary stage of the study aims to validate (technically and pharmacologically) and optimise three different patterns of systemic cortisol administration in man. These patterns are based on the combinatory administration of metyrapone, to suppress endogenous cortisol production, and concurrent hydrocortisone replacement. The second, subsequent, core part of the study is a randomised, double-blinded, placebo-controlled, crossover study, where participants (healthy male individuals aged 18–60 years) will undergo all three hydrocortisone replacement schemes. During these infusion regimes, we plan a number of neurobehavioural tests and imaging of the brain to assess neural processing, emotional reactivity and perception, mood and self-perceived well-being. The psychological tests include: ecological momentary assessment, P1vital Oxford Emotional Test Battery and Emotional Potentiated Startle Test, Leeds Sleep Evaluation Questionnaire and the visual working memory task (n-back). The neuroimaging protocol combines magnetic resonance sequences that capture data related to the functional and perfusion status of the brain. DISCUSSION: Results of this clinical trial are designed to evaluate the impact (with possible mechanistic insights) of different patterns of daily glucocorticoid dynamics on neural processing and reactivity related to emotional perception and mood. This evidence should contribute to the optimisation of the clinical application of glucocorticoid-based therapeutics. TRIAL REGISTRATION: UK Clinical Research Network, IRAS Ref: 106181, UKCRN-ID-15236 (23 October 2013

Synthesising 35 years of invasive non-native species research

The growing focus on the threat of invasive non-native species (INNS) in international biodiversity targets highlights a need for targeted research to support effective understanding, legislation, and management. However, the publishing landscape of invasion biology is complex and expanding rapidly, making consolidation of information increasingly challenging. To identify the major research themes in the INNS literature and to understand how these have changed over the last 35 years, we applied a topic modelling approach. We analysed approximately 10,000 peer-reviewed article abstracts to identify 50 key topics being discussed in the literature. We also quantified how publications on these topics changed over time and how commonly different topics interacted within articles as a measure of their connectedness. Topics covering Population genetics, Policy, First records and Insect biocontrol were the most frequent. Topics were grouped into broad themes, with the largest theme related to Ecosystems, followed by Monitoring, then Management and decision-making. Significant overrepresentation for particular geographical regions and taxa in the literature were apparent. Considering relative changes through time, the most prevalent topics in each decade reflected policy influences, and technological developments. When assessing the degree of connectedness- Policy, Population Genetics and Management Strategies showed low levels of co-occurrence with other topics. This is of particular concern for topics focussed on Policy and Management Strategy as it suggests a weakness at the science-policy interface around accessing and exchanging of evidence. If progress towards future global targets is to be made, we argue that more interdisciplinary research must be encouraged, in particular to better incorporate policy and management considerations into the wider research landscape

Anaesthesia Choice for Creation of Arteriovenous Fistula (ACCess) study protocol : a randomised controlled trial comparing primary unassisted patency at 1 year of primary arteriovenous fistulae created under regional compared to local anaesthesia.

INTRODUCTION: Arteriovenous fistulae (AVF) are the 'gold standard' vascular access for haemodialysis. Universal usage is limited, however, by a high early failure rate. Several small, single-centre studies have demonstrated better early patency rates for AVF created under regional anaesthesia (RA) compared with local anaesthesia (LA). The mechanistic hypothesis is that the sympathetic blockade associated with RA causes vasodilatation and increased blood flow through the new AVF. Despite this, considerable variation in practice exists in the UK. A high-quality, adequately powered, multicentre randomised controlled trial (RCT) is required to definitively inform practice. METHODS AND ANALYSIS: The Anaesthesia Choice for Creation of Arteriovenous Fistula (ACCess) study is a multicentre, observer-blinded RCT comparing primary radiocephalic/brachiocephalic AVF created under regional versus LA. The primary outcome is primary unassisted AVF patency at 1 year. Access-specific (eg, stenosis/thrombosis), patient-specific (including health-related quality of life) and safety secondary outcomes will be evaluated. Health economic analysis will also be undertaken. ETHICS AND DISSEMINATION: The ACCess study has been approved by the West of Scotland Research and ethics committee number 3 (20/WS/0178). Results will be published in open-access peer-reviewed journals within 12 months of completion of the trial. We will also present our findings at key national and international renal and anaesthetic meetings, and support dissemination of trial outcomes via renal patient groups. TRIAL REGISTRATION NUMBER: ISRCTN14153938. SPONSOR: NHS Greater Glasgow and Clyde GN19RE456, Protocol V.1.3 (8 May 2021), REC/IRAS ID: 290482