Derek Renshaw

Annexin 1 mediates the rapid anti-inflammatory effects of neutrophil-derived microparticles

Polymorphonuclear leukocyte (PMN)-derived microparticles display inhibitory properties on target cells as assessed in vitro; since PMNs contain abundant amounts of the endogenous anti-inflammatory protein annexin 1 (AnxA1), we tested here whether biologically active AnxA1 could be present in PMN-derived microparticles. PMN adhesion to human umbilical vein endothelial cell (HUVEC) monolayers led to the generation of microparticles that contained AnxA1, as detected by Western blotting, flow cytometry, and mass spectrometry analyses. Addition of these microparticles to recipient PMNs prior to flow over HUVEC monolayers significantly inhibited cell adhesion, an effect abrogated by a neutralizing anti-AnxA1 antibody, or an antibody raised against the AnxA1 receptor, that is termed lipoxin A(4) receptor or ALX. Intravenous delivery of human PMN-derived microparticles markedly inhibited PMN recruitment to an air pouch inflamed with IL-1beta. This anti-inflammatory effect was also dependent on endogenous AnxA1, since injection of microparticles produced from wild-type PMNs (bone marrow derived), but not from AnxA1-null PMNs, inhibited IL-1beta-induced leukocyte trafficking. In conclusion, PMN-derived microparticles contain functionally active AnxA1 that confers them anti-inflammatory properties; generation of these microparticles in the microcirculation could promote inflammatory resolution by time-dependent dampening of cell recruitment.

The central role of myostatin in skeletal muscle and whole body homeostasis

Myostatin is a powerful negative regulator of skeletal muscle mass in mammalian species. It plays a key role in skeletal muscle homeostasis and has now been well described since its discovery. Myostatin is capable of inducing muscle atrophy via its inhibition of myoblast proliferation, increasing ubiquitin‐proteasomal activity and downregulating activity of the IGF–Akt pathway. These well‐recognized effects are seen in multiple atrophy causing situations, including injury, diseases such as cachexia, disuse and space flight, demonstrating the importance of the myostatin signalling mechanism. Based on this central role, significant work has been pursued to inhibit myostatins actions in vivo. Importantly, several new studies have uncovered roles for myostatin distinct from skeletal muscle size. Myostatin has been suggested to play a role in cardiomyocyte homeostasis, glucose metabolism and adipocyte proliferation, all of which are examined in detail below. Based on these effects, myostatin inhibition has potential to be widely utilized in many Western diseases such as chronic obstructive pulmonary disease, type II diabetes and obesity. However, if myostatin inhibitors are to successfully translate from bench‐top to bedside in the near future, awareness must be raised on these non‐traditional effects of myostatin away from skeletal muscle. Indeed, further research into these novel areas is required.

Characterisation of cystathionine gamma-lyase/hydrogen sulphide pathway in ischaemia/reperfusion injury of the mouse kidney: An in vivo study

The generation of endogenous hydrogen sulphide may either limit or contribute to the degree of tissue injury caused by ischaemia/reperfusion injury. Here, we have attempted to characterise the endogenous hydrogen sulphide synthesis pathway and the effects of sodium hydrosulphide, a hydrogen sulphide donor, in a mouse model of renal ischaemia/reperfusion injury. Anaesthetised male C57/b mice weighing 20-25 g were divided into two groups; (i) Ischaemia/Reperfusion Injury, in which mice were subjected to bilateral renal ischaemia performed by clamping the renal pedicles for 30 min followed by reperfusion for 24 h, (ii) Sham, in which mice were subjected to the same surgical procedures as above, except for renal ischaemia/reperfusion. Western blot analysis of the kidney taken at the end of the experiment demonstrated that cystathionine gamma-lyase, the enzyme responsible for generating hydrogen sulphide in the cardiovascular system, is expressed in the normal kidney and is significantly increased after ischaemia/reperfusion injury. Ischaemia/reperfusion injury significantly increased the rate of hydrogen sulphide production in kidney homogenates and increased the plasma concentration of hydrogen sulphide. In addition, we have shown that administration of the hydrogen sulphide donor sodium hydrosulphide (100 micromol/kg) 30 min prior to ischaemia and 6 h into reperfusion significantly attenuated ischaemia/reperfusion injury-induced renal dysfunction indicated by serum creatinine and urea. These findings suggest that hydrogen sulphide protects the kidney against ischaemia/reperfusion injury and that the increase in expression of the enzyme cystathionine gamma-lyase during ischaemia/reperfusion injury may be one of many endogenous mechanisms to limit renal ischaemia/reperfusion injury.

Saliva: physiology and diagnostic potential in health and disease

Saliva has been described as the mirror of the body. In a world of soaring healthcare costs and an environment where rapid diagnosis may be critical to a positive patient outcome, saliva is emerging as a viable alternative to blood sampling. In this review, we discuss the composition and various physiological roles of saliva in the oral cavity, including soft tissue protection, antimicrobial activities, and oral tissue repair. We then explore saliva as a diagnostic marker of local oral disease and focus particularly on oral cancers. The cancer theme continues when we focus on systemic disease diagnosis from salivary biomarkers. Communicable disease is the focus of the next section where we review the literature relating to the direct and indirect detection of pathogenic infections from human saliva. Finally, we discuss hormones involved in appetite regulation and whether saliva is a viable alternative to blood in order to monitor hormones that are involved in satiety.

Neuropeptide Y and the adrenal gland: a review.

This paper sets out to review several aspects of NPY and adrenal function, starting with the localisation of NPY in the adrenal, then describing the regulation of NPY release and considering whether the adrenal is a significant source of circulating NPY. The review then describes the regulation of adrenal content of peptide, and finally covers the actions of NPY on the adrenal gland, and the receptor subtypes thought to mediate these effects. The regulation and actions of NPY are discussed with reference to both the adrenal cortex and the medulla.

Actions of Neuropeptide Y on the Rat Adrenal Cortex1

Although several studies have demonstrated the presence of neuropeptide Y (NPY) in nerves supplying the mammalian adrenal cortex, its function in this tissue remains unclear, with reports of both stimulatory and inhibitory effects on aldosterone secretion apparently depending on the tissue preparation used. In the present study the effects of NPY on rat adrenal capsular tissue were investigated. NPY significantly stimulated aldosterone secretion in a dose-dependent manner, and this effect was abolished by atenolol, a β1-adrenergic antagonist. NPY also stimulated the release of catecholamines from intact rat adrenal capsular tissue with the same dose-dependent relationship as the stimulation of aldosterone release. These observations suggest that the actions of NPY may be mediated by the local release of catecholamines from chromaffin cells within adrenal capsular tissue, as we have previously described for vasoactive intestinal peptide. The second part of this study concerned the NPY receptor subtype medi...

Attenuation of plasma annexin A1 in human obesity

Obesity‐related metabolic disorders are characterized by mild chronic inflammation, leukocyte infiltration, and tissue fibrosis as a result of adipocytokine production from the expanding white adipose tissue. Annexin A1 (AnxA1) is an endogenous glucocorticoid regulated protein, which modulates systemic anti‐inflammatory processes and, therefore, may be altered with increasing adiposity in humans. Paradoxically, we found that plasma AnxA1 concentrations inversely correlated with BMI, total percentage body fat, and waist‐to‐hip ratio in human subjects. Plasma AnxA1 was also inversely correlated with plasma concentrations of the acute‐phase protein, C‐reactive protein (CRP), and the adipocytokine leptin, suggesting that as systemic inflammation increases, anti‐inflammatory AnxA1 is reduced. In addition, AnxA1 gene expression and protein were significantly up‐regulated during adipogenesis in a human adipocyte cell line compared to vehicle alone, demonstrating for the first time that AnxA1 is expressed and excreted from human adipocytes. These data demonstrate a failure in the endogenous anti‐inflammatory system to respond to increasing systemic inflammation resulting from expanding adipose tissue, a condition strongly linked to the development of type 2 diabetes and cardiovascular disease. These data raise the possibility that a reduction in plasma AnxA1 may contribute to the chronic inflammatory phenotype observed in human obesity.—Kosicka, A., Cunliffe, A. D., Mackenzie, R., Gulrez Zariwala, M., Perretti, M., Flower, R. J., Renshaw, D. Attenuation of plasma annexin A1 in human obesity. FASEB J. 27, 368–378 (2013). www.fasebj.org

Targeting the melanocortin receptor system for anti-stroke therapy

The melanocortin receptors are a subfamily of G-protein-coupled, rhodopsin-like receptors that are rapidly being acknowledged as an extremely promising target for pharmacological intervention in a variety of different inflammatory pathologies, including stroke. Stroke continues to be a leading cause of death worldwide, with risk factors including smoking, diabetes, hypertension and obesity. The pathophysiology of stroke is highly complex: reintroduction of blood flow to the infarcted brain region is paramount in limiting ischaemic damage caused by stroke, yet a concomitant inflammatory response can compound tissue damage. The possibilities of pro-resolving treatments that target this inflammatory response have only recently begun to be explored. This review discusses the endogenous roles of the melanocortin system in reducing characterized aspects of inflammation, and how these, together with potent neuroprotective actions, suggest its potential as a therapeutic target in stroke.

Design and Development of Novel Mitochondrial Targeted Nanocarriers, DQAsomes for Curcumin Inhalation

Curcumin has potent antioxidant and anti-inflammatory properties but poor absorption following oral administration owing to its low aqueous solubility. Development of novel formulations to improve its in vivo efficacy is therefore challenging. In this study, formulation of curcumin-loaded DQAsomes (vesicles formed from the amphiphile, dequalinium) for pulmonary delivery is presented for the first time. The vesicles demonstrated mean hydrodynamic diameters between 170 and 200 nm, with a ζ potential of approximately +50 mV, high drug loading (up to 61%) and encapsulation efficiency (90%), resulting in enhanced curcumin aqueous solubility. Curcumin encapsulation in DQAsomes in the amorphous state was confirmed by X-ray diffraction and differential scanning calorimetry analysis. The existence of hydrogen bonds and cation-π interaction between curcumin and vesicle building blocks, namely dequalinium molecules, were shown in lyophilized DQAsomes using FT-IR analysis. Encapsulation of curcumin in DQAsomes enhanced the antioxidant activity of curcumin compared to free curcumin. DQAsome dispersion was successfully nebulized with the majority of the delivered dose deposited in the second stage of the twin-stage impinger. The vesicles showed potential for mitochondrial targeting. Curcumin-loaded DQAsomes thus represent a promising inhalation formulation with improved stability characteristics and mitochondrial targeting ability, indicating a novel approach for efficient curcumin delivery for effective treatment of acute lung injury and the rationale for future in vivo studies.

A novel approach to oral iron delivery using ferrous sulphate loaded solid lipid nanoparticles.

Iron (Fe) loaded solid lipid nanoparticles (SLNs) were formulated using stearic acid and iron absorption was evaluated in vitro using the cell line Caco-2 with intracellular ferritin formation as a marker of iron absorption. Iron loading was optimised at 1% Fe (w/w) lipid since an inverse relation was observed between initial iron concentration and SLN iron incorporation efficiency. Chitosan (Chi) was included to prepare chitosan coated SLNs. Particle size analysis revealed a sub-micron size range (300.3±31.75 nm to 495.1±80.42 nm), with chitosan containing particles having the largest dimensions. As expected, chitosan (0.1%, 0.2% and 0.4% w/v) conferred a net positive charge on the particle surface in a concentration dependent manner. For iron absorption experiments equal doses of Fe (20 μM) from selected formulations (SLN-FeA and SLN-Fe-ChiB) were added to Caco-2 cells and intracellular ferritin protein concentrations determined. Caco-2 iron absorption from SLN-FeA (583.98±40.83 ng/mg cell protein) and chitosan containing SLN-Fe-ChiB (642.77±29.37 ng/mg cell protein) were 13.42% and 24.9% greater than that from ferrous sulphate (FeSO4) reference (514.66±20.43 ng/mg cell protein) (p≤0.05). We demonstrate for the first time preparation, characterisation and superior iron absorption in vitro from SLNs, suggesting the potential of these formulations as a novel system for oral iron delivery.