Role of the GPR55 receptor in the modulation of joint afferent mechanosensitivity

Deep somatic pain originating from synovial joints is a major clinical problem as it is the primary reason for loss of joint mobility and function in musculoskeletal disorders. Musculoskeletal disorders, including osteoarthritis (OA), are the most prevalent cause of disability worldwide with an estimated 1 in 3 adults affected. Current therapies for the treatment of joint pain have limited effectiveness and certain drugs produce unwanted side effects, preventing their long-term use. Targeting pain at the level of the joint may have the potential to maximise treatment efficacy, whilst reducing possible non- specific side effects associated with systemic drug treatment. Identification of novel analgesic targets that inhibit peripheral mechanical sensitization during joint pain states will be critical to the development of improved analgesics for these conditions. Based on recent preclinical findings, the orphan G protein- coupled receptor GPR55 has controversially been suggested to be the novel third cannabinoid receptor and has been identified as a potential novel target for the treatment of pain. Very few studies have investigated the effects of GPR55 activation on nociceptive processing in vivo and only one at the level of the joint during acute inflammatory arthritis. The aim of this thesis was to investigate the role of GPR55 in the modulation of joint afferent mechanosensitivity in vivo, and whether this role is altered in an experimental model of OA during established pain. Electrophysiological recordings of joint afferent nociceptors, taken from the saphenous nerve, which innervates the knee joint via the medial articular nerve, were carried out in anaesthetised rats under non-pathological conditions (naïve rats) and in a model of OA following the development of pain behaviour, 14 days following knee joint injection of monosodium iodoacetate (MIA) and compared to saline control rats. Effects of peripheral administration of the putative endogenous GPR55 agonist L-α-lysophosphatidylinositol (LPI) on the mechanically-evoked responses of joint nociceptors were studied in naïve rats and in MIA and saline rats. An involvement of GPR55 in the effects of LPI was investigated using pre-administration of the GPR55 antagonist cannabidiol. Further, the role of GPR55 in endogenously modulating joint afferent mechanosensitivity was investigated following the peripheral administration of cannabidiol alone. GPR55 expression in knee innervating L3- L5 rat DRGs was studied by immunohistochemistry. Joint nociceptors in MIA rats were mechanically sensitized compared to the saline rats at 14 days post-injection confirming the development of peripheral sensitization during established pain behaviour. LPI (150, 250μM) inhibited joint nociceptor mechanically-evoked responses in naïve and saline rats and inhibited peripheral sensitization in MIA rats. Cannabidiol blocked the LPI- induced inhibition of joint nociceptor mechanosensitivity in all groups of rats confirming an involvement of GPR55 in these effects. Cannabidiol alone had no effect on mechanically-evoked responses of joint nociceptors in naïve, saline and MIA rats indicating that any endogenous GPR55 tone does not modulate joint afferent mechanosensitivity. GPR55 expression was detected in small, medium and large neurones (and possibly satellite glial cells) of L3-L5 DRG. The findings of this thesis provide compelling evidence that activation of GPR55 in vivo modulates the mechanosensitivity of joint afferent nociceptors and this inhibitory effect is maintained during established peripheral sensitization and pain behaviour following OA development. GPR55-mediated control of joint afferent mechanosensitivity during established OA pain and expression of GPR55 in sensory neurones at the level innervating the joint highlights GPR55 as a potential new peripheral target for the modulation of joint pain including during OA. The findings of this thesis support further studies aimed at investigating the clinical utility of GPR55 agonists for the treatment of OA pain

Role of the GPR55 receptor in the modulation of joint afferent mechanosensitivity

Deep somatic pain originating from synovial joints is a major clinical problem as it is the primary reason for loss of joint mobility and function in musculoskeletal disorders. Musculoskeletal disorders, including osteoarthritis (OA), are the most prevalent cause of disability worldwide with an estimated 1 in 3 adults affected. Current therapies for the treatment of joint pain have limited effectiveness and certain drugs produce unwanted side effects, preventing their long-term use. Targeting pain at the level of the joint may have the potential to maximise treatment efficacy, whilst reducing possible non- specific side effects associated with systemic drug treatment. Identification of novel analgesic targets that inhibit peripheral mechanical sensitization during joint pain states will be critical to the development of improved analgesics for these conditions. Based on recent preclinical findings, the orphan G protein- coupled receptor GPR55 has controversially been suggested to be the novel third cannabinoid receptor and has been identified as a potential novel target for the treatment of pain. Very few studies have investigated the effects of GPR55 activation on nociceptive processing in vivo and only one at the level of the joint during acute inflammatory arthritis. The aim of this thesis was to investigate the role of GPR55 in the modulation of joint afferent mechanosensitivity in vivo, and whether this role is altered in an experimental model of OA during established pain. Electrophysiological recordings of joint afferent nociceptors, taken from the saphenous nerve, which innervates the knee joint via the medial articular nerve, were carried out in anaesthetised rats under non-pathological conditions (naïve rats) and in a model of OA following the development of pain behaviour, 14 days following knee joint injection of monosodium iodoacetate (MIA) and compared to saline control rats. Effects of peripheral administration of the putative endogenous GPR55 agonist L-α-lysophosphatidylinositol (LPI) on the mechanically-evoked responses of joint nociceptors were studied in naïve rats and in MIA and saline rats. An involvement of GPR55 in the effects of LPI was investigated using pre-administration of the GPR55 antagonist cannabidiol. Further, the role of GPR55 in endogenously modulating joint afferent mechanosensitivity was investigated following the peripheral administration of cannabidiol alone. GPR55 expression in knee innervating L3- L5 rat DRGs was studied by immunohistochemistry. Joint nociceptors in MIA rats were mechanically sensitized compared to the saline rats at 14 days post-injection confirming the development of peripheral sensitization during established pain behaviour. LPI (150, 250μM) inhibited joint nociceptor mechanically-evoked responses in naïve and saline rats and inhibited peripheral sensitization in MIA rats. Cannabidiol blocked the LPI- induced inhibition of joint nociceptor mechanosensitivity in all groups of rats confirming an involvement of GPR55 in these effects. Cannabidiol alone had no effect on mechanically-evoked responses of joint nociceptors in naïve, saline and MIA rats indicating that any endogenous GPR55 tone does not modulate joint afferent mechanosensitivity. GPR55 expression was detected in small, medium and large neurones (and possibly satellite glial cells) of L3-L5 DRG. The findings of this thesis provide compelling evidence that activation of GPR55 in vivo modulates the mechanosensitivity of joint afferent nociceptors and this inhibitory effect is maintained during established peripheral sensitization and pain behaviour following OA development. GPR55-mediated control of joint afferent mechanosensitivity during established OA pain and expression of GPR55 in sensory neurones at the level innervating the joint highlights GPR55 as a potential new peripheral target for the modulation of joint pain including during OA. The findings of this thesis support further studies aimed at investigating the clinical utility of GPR55 agonists for the treatment of OA pain

Umpolung Synthesis of Pyridyl Ethers by Bi(V)‐Mediated O‑Arylation of Pyridones

We report that O-selective arylation of 2- and 4-pyridones with arylboronic acids is affected by a modular, bismacycle-based system. The utility of this umpolung approach to pyridyl ethers, which is complementary to conventional methods based on S N Ar or cross-coupling, is demonstrated through the concise synthesis of Ki6783 and picolinafen, and the formal synthesis of cabozantib and golvatinib. Computational investigations reveal that arylation proceeds in a concerted fashion via a 5-membered transition state. The kinetically-controlled regioselectivity for O-arylation – which is reversed relative to previous Bi(V)-mediated pyridone arylations – is attributed primarily to the geometric constraints imposed by the bismacyclic scaffold

Evaluating the potential for the environmentally sustainable control of foot and mouth disease in Sub-Saharan Africa

Strategies to control transboundary diseases have in the past generated unintended negative consequences for both the environment and local human populations. Integrating perspectives from across disciplines, including livestock, veterinary and conservation sectors, is necessary for identifying disease control strategies that optimise environmental goods and services at the wildlife-livestock interface. Prompted by the recent development of a global strategy for the control and elimination of foot-and-mouth disease (FMD), this paper seeks insight into the consequences of, and rational options for potential FMD control measures in relation to environmental, conservation and human poverty considerations in Africa. We suggest a more environmentally nuanced process of FMD control that safe-guards the integrity of wild populations and the ecosystem dynamics on which human livelihoods depend while simultaneously improving socio-economic conditions of rural people. In particular, we outline five major issues that need to be considered: 1) improved understanding of the different FMD viral strains and how they circulate between domestic and wildlife populations; 2) an appreciation for the economic value of wildlife for many African countries whose presence might preclude the country from ever achieving an FMD-free status; 3) exploring ways in which livestock production can be improved without compromising wildlife such as implementing commodity-based trading schemes; 4) introducing a participatory approach involving local farmers and the national veterinary services in the control of FMD; and 5) finally the possibility that transfrontier conservation might offer new hope of integrating decision-making at the wildlife-livestock interface

High-yield methods for accurate two-alternative visual psychophysics in head-fixed mice

Research in neuroscience increasingly relies on the mouse, a mammalian species that affords unparalleled genetic tractability and brain atlases. Here, we introduce high-yield methods for probing mouse visual decisions. Mice are head-fixed, facilitating repeatable visual stimulation, eye tracking, and brain access. They turn a steering wheel to make two alternative choices, forced or unforced. Learning is rapid thanks to intuitive coupling of stimuli to wheel position. The mouse decisions deliver high-quality psychometric curves for detection and discrimination and conform to the predictions of a simple probabilistic observer model. The task is readily paired with two-photon imaging of cortical activity. Optogenetic inactivation reveals that the task requires mice to use their visual cortex. Mice are motivated to perform the task by fluid reward or optogenetic stimulation of dopamine neurons. This stimulation elicits a larger number of trials and faster learning. These methods provide a platform to accurately probe mouse vision and its neural basis

Controversies Surrounding Renal Denervation:Lessons Learned From Real-World Experience in Two United Kingdom Centers

Renal denervation (RDN) is a therapy that targets treatment‐resistant hypertension (TRH). The Renal Denervation in Patients With Uncontrolled Hypertension (Symplicity) HTN‐1 and Symplicity HTN‐2 trials reported response rates of >80%; however, sham‐controlled Symplicity HTN‐3 failed to reach its primary blood pressure (BP) outcome. The authors address the current controversies surrounding RDN, illustrated with real‐world data from two centers in the United Kingdom. In this cohort, 52% of patients responded to RDN, with a 13±32 mm Hg reduction in office systolic BP (SBP) at 6 months (n=29, P=.03). Baseline office SBP and number of ablations correlated with office SBP reduction (R=−0.47, P=.01; R=−0.56, P=.002). RDN appears to be an effective treatment for some patients with TRH; however, individual responses are highly variable. Selecting patients for RDN is challenging, with only 10% (33 of 321) of the screened patients eligible for the study. Medication alterations and nonadherence confound outcomes. Adequate ablation is critical and should impact future catheter design/training. Markers of procedural success and improved patient selection parameters remain key research aims

Sensory neuronal sensitisation occurs through HMGB-1/RAGE and TRPV1 in high glucose conditions

Many potential causes for painful diabetic neuropathy have been proposed including actions of cytokines and growth factors. High mobility group protein B1 (HMGB1) is a RAGE agonist, increased in diabetes, that contributes to pain by modulating peripheral inflammatory responses. HMGB1 enhances nociceptive behaviour in naïve animals through an unknown mechanism. We tested the hypothesis that HMGB1 causes pain through direct neuronal activation of RAGE and alteration of nociceptive neuronal responsiveness. HMGB1 and RAGE expression were increased in skin and primary sensory (DRG) neurons of diabetic rats at times when pain behaviour was enhanced. Agonist-evoked TRPV1-mediated calcium responses increased in cultured DRG neurons from diabetic rats and in neurons from naïve rats exposed to high glucose concentrations. HMGB1-mediated increases in TRPV1-evoked calcium responses in DRG neurons were RAGE and PKC-dependent, and this was blocked by co-administration of the growth factor splice variant, VEGF-A165b. Pain behaviour and DRG RAGE expression increases were blocked by VEGF-A165b treatment of diabetic rats in vivo. HMGB-1-RAGE activation sensitizes DRG neurons in vitro. VEGF-A165b blocks HMGB-1/RAGE DRG activation, which may contribute to its analgesic properties in vivo

Detection of neutralising antibodies to SARS-CoV-2 to determine population exposure in Scottish blood donors between March and May 2020.

BackgroundThe progression and geographical distribution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the United Kingdom (UK) and elsewhere is unknown because typically only symptomatic individuals are diagnosed. We performed a serological study of blood donors in Scotland in the spring of 2020 to detect neutralising antibodies to SARS-CoV-2 as a marker of past infection and epidemic progression.AimOur objective was to determine if sera from blood bank donors can be used to track the emergence and progression of the SARS-CoV-2 epidemic.MethodsA pseudotyped SARS-CoV-2 virus microneutralisation assay was used to detect neutralising antibodies to SARS-CoV-2. The study comprised samples from 3,500 blood donors collected in Scotland between 17 March and 18 May 2020. Controls were collected from 100 donors in Scotland during 2019.ResultsAll samples collected on 17 March 2020 (n = 500) were negative in the pseudotyped SARS-CoV-2 virus microneutralisation assay. Neutralising antibodies were detected in six of 500 donors from 23 to 26 March. The number of samples containing neutralising antibodies did not significantly rise after 5-6 April until the end of the study on 18 May. We found that infections were concentrated in certain postcodes, indicating that outbreaks of infection were extremely localised. In contrast, other areas remained comparatively untouched by the epidemic.ConclusionAlthough blood donors are not representative of the overall population, we demonstrated that serosurveys of blood banks can serve as a useful tool for tracking the emergence and progression of an epidemic such as the SARS-CoV-2 outbreak

Welfare and education in British colonial Africa, 1918–1945

The relevance of historical research for an explanation of the roots of contemporary educational policy and its relationship to notions of equity, democracy and development has been sadly neglected in recent years. This means that policy makers have forfeited the advantages of reflecting on the traditions and experience of past endeavors and examining them critically for potential understandings of present and future policy making. The aim of this paper was to direct the attention of researchers to the complexities and multifaceted nature of educational policy development in inter-war era (1918–1945), with specific reference to British colonial Africa and South Africa. It will also hopefully provide a set of elementary tools for all of those interested in educational policy-making strategies that seek to promote meaningful social, economic and political change in an age of uncertainty

Shiga Toxin 1 Induces on Lipopolysaccharide-Treated Astrocytes the Release of Tumor Necrosis Factor-alpha that Alter Brain-Like Endothelium Integrity

The hemolytic uremic syndrome (HUS) is characterized by hemolytic anemia, thrombocytopenia and renal dysfunction. The typical form of HUS is generally associated with infections by Gram-negative Shiga toxin (Stx)-producing Escherichia coli (STEC). Endothelial dysfunction induced by Stx is central, but bacterial lipopolysaccharide (LPS) and neutrophils (PMN) contribute to the pathophysiology. Although renal failure is characteristic of this syndrome, neurological complications occur in severe cases and is usually associated with death. Impaired blood-brain barrier (BBB) is associated with damage to cerebral endothelial cells (ECs) that comprise the BBB. Astrocytes (ASTs) are inflammatory cells in the brain and determine the BBB function. ASTs are in close proximity to ECs, hence the study of the effects of Stx1 and LPS on ASTs, and the influence of their response on ECs is essential. We have previously demonstrated that Stx1 and LPS induced activation of rat ASTs and the release of inflammatory factors such as TNF-α, nitric oxide and chemokines. Here, we demonstrate that rat ASTs-derived factors alter permeability of ECs with brain properties (HUVECd); suggesting that functional properties of BBB could also be affected. Additionally, these factors activate HUVECd and render them into a proagregant state promoting PMN and platelets adhesion. Moreover, these effects were dependent on ASTs secreted-TNF-α. Stx1 and LPS-induced ASTs response could influence brain ECs integrity and BBB function once Stx and factors associated to the STEC infection reach the brain parenchyma and therefore contribute to the development of the neuropathology observed in HUS