About
76
Publications
7,606
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
2,534
Citations
Introduction
Biochemist/cell biologist with interests in pro-inflammatory signalling networks and gene expression, especially the activity of proteases and ECM turnover in disease (osteoarthritis and co-morbidities such as obesity).
Since 2017 I have been part of BREATH (Border and REgions Airways Training Hub): a major cross-border partnership (academic/clinical/enterprise) focused on better understanding, treatment, diagnosis, management and awareness of chronic obstructive pulmonary disease (COPD).
Additional affiliations
January 2013 - present
Education
June 2014 - June 2015
October 1992 - December 1995
October 1988 - June 1992
Publications
Publications (76)
Background
Small extracellular vesicles (sEV) derived from synovial fibroblasts (SF) represent a novel molecular mechanism regulating cartilage erosion in osteoarthritis (OA). However, a comprehensive evaluation using disease relevant cells has not been undertaken. The aim of this study was to isolate and characterise sEV from OA SF and to look at...
Recent evidence indicates that microbial biofilm aggregates inhabit the lungs of COPD patients and actively contribute towards chronic colonization and repeat infections. However, there are no contextually relevant complex biofilm models for COPD research. In this study, a meta‐analysis of the lung microbiome in COPD was used to inform development...
Exercise is recommended as a non-pharmacological therapy for osteoarthritis (OA). Various exercise regimes, with differing intensities and duration, have been used in a range of OA rodent models. These studies show gentle or moderate exercise reduces the severity of OA parameters while high intensity load bearing exercise is detrimental. However, t...
Candida albicans is an opportunistic pathogen found throughout multiple body sites and is frequently co-isolated from infections of the respiratory tract and oral cavity with Staphylococcus aureus. Herein we present the first report of the effects that S. aureus elicits on the C. albicans transcriptome. Dual-species biofilms containing S. aureus an...
Exercise is recommended as a non-pharmacological therapy for osteoarthritis (OA). Clinical studies investigating the impact of exercise on OA have primarily focussed on the assessment of joint pain and mobilisation, where positive outcomes have been demonstrated. Clinical imaging studies provide limited information on the impact of exercise (positi...
A number of clinical studies have defined the lung microbiome of chronic obstructive pulmonary disease (COPD) patients. However, these studies are limited by several factors such as cohort size, lack of standardised processing and analysis methods as well as being confined to a single geographic location. Herein, a meta-analysis of publically avail...
Chronic obstructive pulmonary disease (COPD) is a debilitating heterogeneous disease characterised by unregulated proteolytic destruction of lung tissue mediated via a protease-antiprotease imbalance. In COPD, the relationship between the neutrophil serine protease, neutrophil elastase, and its endogenous inhibitor, alpha-1-antitrypsin (AAT) is the...
Trypsin-like proteases (TLPs) belong to a family of serine enzymes with primary substrate specificities for the basic residues, lysine and arginine, in the P1 position. Whilst initially perceived as soluble enzymes that are extracellularly secreted, a number of novel TLPs that are anchored in the cell membrane have since been discovered. Muco-obstr...
Cigarette smoke stimulates an inflammatory response and produces oxidants that cause oxidative stress in the lung, promoting pathophysiological changes related to chronic obstructive pulmonary disease (COPD).¹ Hydrogen peroxide (H2O2) is an important oxidant detected in breath condensate of COPD patients.² We aim to understand how chronic exposure...
Lungs from patients with chronic obstructive pulmonary disease (COPD) display hallmarks of premature ageing including reduced autophagy, contributing to cellular senescence. The mechanisms underlying dysregulated lung autophagy remain unclear and under researched. While proteinase activated receptor-2 (PAR2) is a potential therapeutic target for in...
Inflammatory cytokine production is a hallmark of COPD. PAR2 activation, via the transmembrane serine protease matriptase, results in the regulation of pro-inflammatory cytokines, including IL-6 and IL-8 (Seitz et al., 2007). The aim of this study was to investigate a putative role for PAR2 in COPD. PAR2 and matriptase expression was determined by...
Osteoarthritis (OA) is the most prevalent of the musculoskeletal conditions and represents a significant public health burden. While degeneration of articular cartilage is a key feature, it is now increasingly recognized as a complex condition affecting the whole joint, with synovial inflammation present in a significant proportion of patients. As...
Objective:
Joint injury involving destabilisation of the joint and damage to the articular cartilage (e.g., sports-related injury) can result in accelerated post-traumatic osteoarthritis (PTOA). Destabilised medial meniscotibial ligament (DMM) surgery is one of the most commonly used murine models and whilst it recapitulates Osteoarthritis (OA) pa...
Purpose of Review
Chronic cough, defined in adults as one lasting longer than 8 weeks, is among the commonest clinical problems encountered by doctors both in general practice and in hospital. It can exist as a distinct clinical problem or as a prominent and troublesome symptom for patients with common pulmonary conditions including asthma, chronic...
In the UK, over 1 million people live with diagnosed chronic obstructive pulmonary disease (COPD) however, it is estimated that this is only 1/3 of the total COPD population. Diagnosis is based on patient airflow obstruction, a late developing symptom, by which time a significant amount of lung damage has already occurred (1). Investigation into a...
Irreversible cartilage collagen breakdown by the collagenolytic matrix metalloproteinases (MMPs)-1 and MMP-13 represents a key event in pathologies associated with tissue destruction such as arthritis. Inflammation is closely associated with such pathology and occurs in both rheumatoid and osteoarthritis making it highly relevant to the prevailing...
Confirmation of antibody specificity using human chondrocyte lysates.
The specificity of each antibody used in the study was confirmed using nuclear lysates prepared as described in the Methods from primary human articular chondrocytes either unstimulated or stimulated with IL-1 (0.2 ng/mL) in combination with OSM (10 ng/mL). Following SDS-PAGE, pr...
Multiple transcriptional regulators impact on MMP13 gene expression.
Following transfection with siRNA specific for the indicated genes or non-targeting control (siCon; all 100 nM), Human chondrocytes were treated with IL-1 (0.05 ng/ml) in combination with OSM (10 ng/ml) for 24 hours. RNA isolated from three separate populations were subjected to q...
Multiple transcriptional regulators are induced following IL-1+OSM stimulation of human chondrocytes.
Human chondrocytes were treated with IL-1 (0.05 ng/mL) in combination with OSM (10 ng/mL) for 1, 1.25 or 24 h and total RNA isolated. RNA from three separate populations (#1, #2 and #3 as presented in Figs 4 and 5) was profiled using the Human HT-1...
Protease-activated receptor-2 (PAR2) is one member of a small family of transmembrane, G-protein-coupled receptors. These receptors are activated via cleavage of their N terminus by serine proteases (e.g., tryptase), unveiling an N terminus tethered ligand which binds to the second extracellular loop of the receptor. Increasing evidence has emerged...
Many catabolic stimuli, including interleukin-1 (IL-1) in combination with oncostatin M (OSM), promote cartilage breakdown via the induction of collagen-degrading collagenases such as matrix metalloproteinase 1 (MMP1) and MMP13 in human articular chondrocytes. Indeed, joint diseases with an inflammatory component are characterised by excessive extr...
Effect of PKD inhibition on collagenase expression in human chondrocytes.
Primary human articular chondrocytes were stimulated with IL-1 (0.2 ng/ml) alone, OSM (10 ng/ml) alone or IL-1+OSM as detailed in the Methods for 20 min. Cells were pre-treated with Gӧ6983 (20 μM; PKCi) or a DMSO vehicle control for 1 h prior to stimulation, and then lysed an...
Gene silencing of PRKD3 selectively supresses cytokine-induced MMP expression.
Following transfection with siRNA specific for PRKD3 or a non-targeting siCon (100 nM), primary human articular chondrocytes were stimulated with IL-1+OSM as described in the Methods for 24 h. Cell lysates were then subjected to real-time PCR (n = 6; mean ± S.E.) for MMP...
Gene silencing of PRKD1 or PRKD2 does not supress cytokine-induced FOS and JUN expression.
Following transduction with lentiviral shRNA (MOI = 30) specific to PRKD1 or shCon (A), or transfection with siRNA specific for PRKD2 or a non-targeting siCon (100 nM) (B), primary human articular chondrocytes were stimulated with IL-1+OSM as described in the...
Confirmation of antibody specificity using human chondrocyte lysates.
The specificity of each antibody used in the study was confirmed using whole cell lysates, except for MEK2 and lamin A/C (cytoplasmic and nuclear extracts, respectively), prepared as described in the Methods from primary human articular chondrocytes either unstimulated or stimula...
Confirmation of kinase isoform knockdown following gene silencing in primary human chondrocytes.
Specificity of shRNA and siRNAs was assessed in primary human articular chondrocytes using immunoblotting (using the antibodies indicated), whilst fluorescent microscopy was also used to assess lentiviral transduction. Following transfection with siRNA...
Gene silencing of PRKD1 or PRKD2 does not supress cytokine-induced MMP1/13 expression.
Following transduction with lentiviral shRNA (MOI = 30) specific to PRKD1 or shCon (A), or transfection with siRNA specific for PRKD2 or a non-targeting siCon (100 nM) (B), primary human articular chondrocytes were stimulated with IL-1+OSM as described in the Met...
Cellular senescence is a state of stable proliferation arrest of cells. The senescence pathway has many beneficial effects and is seen to be activated in damaged/stressed cells, as well as during embryonic development and wound healing. However, the persistence and accumulation of senescent cells in various tissues can also impair function and have...
Irreversible breakdown of cartilage extracellular matrix (ECM) by the collagenase matrix metalloproteinase 13 (MMP13) represents a key event in osteoarthritis (OA) progression. Although inflammation is most commonly associated with inflammatory joint diseases, it also occurs in OA and is thus relevant to the prevalent tissue destruction. Here, infl...
The pseudo-kinase family of tribbles (TRIB) proteins has been linked to a variety of cell signalling pathways and appears to have functionally divergent roles with respect to intracellular protein degradation and the ability to regulate signal transduction pathways. In the arthritides, inflammation and a wide variety of proinflammatory pathways hav...
Objective:
To assess the role of glycogen synthase kinase 3 (GSK-3) as a regulator of cartilage destruction in human tissue and a murine model of osteoarthritis (OA).
Methods:
Surgical destabilization of the medial meniscus (DMM) was performed to induce experimental murine OA, and joint damage was assessed histologically. Bovine nasal and human...
To investigate the effect of leptin on cartilage destruction.
Collagen release was assessed in bovine cartilage explant cultures, while collagenolytic and gelatinolytic activities in culture supernatants were determined by bioassay and gelatin zymography. The expression of matrix metalloproteinases (MMP) was analysed by real-time RT-PCR. Signalling...
To determine the effects and mechanism of action of lithium chloride (LiCl) on cartilage destruction induced by the pro-inflammatory cytokines IL-1, IL-1 + oncostatin M and TNF-α.
The release of collagen was assessed in bovine cartilage explant cultures, whereas collagenolytic activities (active and total) in conditioned culture supernatants were d...
Histone deacetylases (HDACs) regulate the acetylation of histones in the control of gene expression. Many non-histone proteins are also targeted for acetylation, including TGF-β signalling pathway components such as Smad2, Smad3 and Smad7. Our studies in mouse C3H10T1/2 fibroblasts suggested that a number of TGF-β-induced genes that regulate matrix...
The protein kinase C (PKC) signaling pathway is a major regulator of cellular functions and is implicated in pathologies involving extracellular matrix remodeling. Inflammatory joint disease is characterized by excessive extracellular matrix catabolism, and here we assess the role of PKC in the induction of the collagenases, matrix metalloproteinas...
tub encodes a protein of poorly understood function, but one implicated strongly in the control of energy balance and insulin sensitivity. Whilst tub expression is particularly prominent in neurones it is also detectable in extraneuronal tissues. We show here, for the first time, expression of TUB protein in rat adipocytes and the murine adipocyte...
The phosphatidylinositol 3-kinase (PI3K) signaling pathway has emerged as a major regulator of cellular functions and has been implicated in several pathologies involving remodeling of extracellular matrix (ECM). The end stage of inflammatory joint diseases is characterized by excessive ECM catabolism, and in this study we assess the role of PI3K s...
To characterise the catabolic response of osteoarthritic chondrocytes to Toll-like receptor (TLR) ligands.
Induction of the collagenases, matrix metalloproteinase (MMP)1 and MMP13, by TLR ligands was assessed in chondrocytes by real-time reverse transcriptase (RT)-PCR. TLR signalling pathway activation and their involvement in collagenase induction...
Dysregulated proteolysis of the extracellular matrix of articular cartilage represents a unifying hallmark of the arthritides, and has been a target for therapeutic intervention for some time, although clinical efficacy has been elusive. Members of the 'A disintegrin and metalloprotease with thrombospondin motifs' and matrix metalloprotease familie...
Elevated non-esterified fatty acids, triglyceride, diacylglycerol, and ceramide have all been associated with insulin resistance in muscle. We set out to investigate the role of intramyocellular lipid metabolites in the induction of insulin resistance in human primary myoblast cultures. Muscle cells were subjected to adenovirus-mediated expression...
We have used primary human muscle cell cultures to investigate the role of glycogen loading in cellular insulin resistance. Insulin pre-treatment for 2 h markedly impaired insulin signaling, as assessed by protein kinase B (PKB) phosphorylation. In contrast, insulin-dependent glycogen synthesis, glycogen synthase (GS) activation, and GS sites 3 de-...
NupG from Escherichia coli is the archetype of a family of nucleoside transporters found in several eubacterial groups and has distant homologues in eukaryotes, including man. To facilitate investigation of its molecular mechanism, we developed methods for expressing an oligohistidine-tagged form of NupG both at high levels (>20% of the inner membr...
Fructose is a major dietary sugar, which is elevated in the serum of diabetic humans, and is associated with metabolic syndromes important in the pathogenesis of diabetic complications. The facilitative fructose transporter, GLUT5, is expressed in insulin-sensitive tissues (skeletal muscle and adipocytes) of humans and rodents, where it mediates th...
Skeletal muscle, a primary insulin target tissue, expresses the GLUT5 fructose transporter. Although insulin has no acute effect on GLUT5 expression and function in muscle, we show here that long-term (24 h) insulin treatment of L6 muscle cells induces a dose-dependent increase in GLUT5 protein (by up to two-fold), leading to a concomitant increase...
The rate of glucose transport into cells is of fundamental importance in whole body homeostasis and adaptation to metabolic stresses, and this review examines the signalling mechanisms controlling this process. The events that mediate the action of insulin on glucose transport, which is by far the best characterized paradigm for glucose transport r...
The rate of glucose transport into cells is of fundamental importance in whole body homeostasis and adaptation to metabolic stresses, and this review examines the signalling mechanisms controlling this process. The events that mediate the action of insulin on glucose transport, which is by far the best characterized paradigm for glucose transport r...
The recently cloned amino acid transporter SAT2 is ubiquitously expressed and confers Na(+)-dependent transport of short-chain neutral amino acids, characteristics of the functionally defined System A transporter. Here we report the presence of SAT2 mRNA and protein in both skeletal muscle and adipocytes, and the characterization of polyclonal anti...
The serine/threonine kinase protein kinase B (PKB/Akt) has been shown to play a crucial role in the control of diverse and important cellular functions such as cell survival and glycogen metabolism. There is also convincing evidence that PKB plays a role in the insulin-mediated regulation of glucose transport. Furthermore, states of cellular insuli...
Increased cellular production of ceramide has been implicated in the pathogenesis of insulin resistance and in the impaired utilisation of glucose. In this study we have used L6 muscle cells to investigate the mechanism by which the short-chain ceramide analogue, C2-ceramide, promotes a loss in insulin sensitivity leading to a reduction in insulin...
We show here that cytochalasin D-induced depolymerization of actin filaments markedly reduces the stimulus-dependent activation of protein kinase B (PKB) in four different cell types (HEK-293 cells, L6 myotubes, 3T3-L1 adipocytes and U87MG cells). HEK-293 cells expressing the pleckstrin homology (PH) domains of PKB and general receptor for phosphoi...
Transport of ammonium across biological membranes is an important process in a number of organisms, ranging from bacteria to plants and humans. The first genetic identification of an ammonium transporter was in 1994, which led to the characterisation of the Mep/Amt proteins in Saccharomyces cerevisiae and Arabidopsis rhaliana. These proteins have s...
We have investigated the cellular mechanisms that participate in reducing insulin sensitivity in response to increased oxidant stress in skeletal muscle. Measurement of glucose transport and glycogen synthesis in L6 myotubes showed that insulin stimulated both processes, by 2- and 5-fold, respectively. Acute (30 min) exposure of muscle cells to hyd...
At 100 nM both thymeleatoxin (TX) and 12-0-tetradecanoylphorbol-13-acetate (TPA) maximally stimulated the release of choline metabolites from C6 glioma cells to the external medium by 2.5 to 3 times over basal: for 12-deoxyphorbol-13-phenylacetate-20-acetate (DOPPA) at 100 nM the increase was only 1.8 times over basal. At DOPPA concentrations betwe...