Biology subjects

Bates, D. O.

Publications and source records attributed to Bates, D. O..

4 recordsLinked to original sources

bioRxiv2024

The splicing factor kinase SRPK1 is a therapeutic target for Peripheral Vascular Disease

IntroductionIn peripheral arterial disease (PAD) anti-angiogenic VEGF-A165b isoform overexpression in monocytes contributes to impaired collateralisation. Serine-arginine protein-kinase-1 (SRPK1) regulates VEGF splicing. To determine whether SRPK1 controlled monocytic VEGF, impairing collateralisation, we investigated SRPK1 inhibition and monocyte-specific knockout in mouse models of and in human monocytes from PAD. MethodsVEGF-A165b activity was measured by co-culture of PAD patients monocytes with endothelial cells with SRPK1 inhibition. Mice with impaired revascularisation due to soluble-frizzled-related-protein-5 knockout (Sfrp5-/-), monocyte-specific Wnt5a gain-of-function (LysM-Wnt5aGOF), or obese mice on a high-fat high-sucrose (HF/HS) diet were subjected to femoral artery ligation and treated with SRPK1 inhibitor. We generated an SRPK1 conditional knockout and crossed it with monocyte-specific (LysM-Cre) driver line to specifically knockout SRPK1 in monocyte lineages. Blood flow was measured by Laser Speckle Imaging before, and for 28 days after surgery. ResultsMonocytes from PAD patients significantly inhibited endothelial cell migration, which was reversed by an anti-VEGF-A165b antibody. Surprisingly, migration was stimulated by SRPK1 inhibition, switching splicing from VEGF-A165b to VEGF-A165a. In Sfrp5-/-, LysM-Wnt5aGOF and HF/HS mouse models of PAD, blood flow was improved by SRPK1 inhibition. Impaired revascularisation in LysM-Wnt5aGOF mice was rescued in LysM-Wnt5aGOF:SRPK1MoKO mice, which had a phenotypic shift towards M2 macrophages. Impaired blood flow recovery was also rescued in obese-SRPK1MoKO mice. ConclusionVEGF splicing in monocytes is regulated differently from VEGF splicing in epithelial or cancer cells suggesting that control of splicing is dependent on cell type and/or environment. SRPK1 inhibition enhances collateralisation in mice, and in human in vitro models of monocyte-dependent impaired angiogenesis. New and NoteworthyA novel potential treatment for peripheral arterial disease (PAD) is described. Inhibition of SRPK1, or knockout in monocytes, induces angiogenesis by preventing splicing to anti-angiogenic VEGF (VEGF-A165b) in patients and animal models. In PAD, monocyte splicing control is different from other cell types and SRPK1 inhibition by drug like compounds can alter macrophage phenotype and reverse PAD in mice using a new cell specific SRPK1-LoxP mouse.

physiology↗

bioRxiv2023

Angiotensin II type 1 receptor activation facilitates pain hypersensitivity via dorsal horn pericyte mediated vasoconstriction

Vascular disturbance is a key factor in the development of neurological disease, with reduced integrity of the capillary network in the dorsal horn implicated in activation of nociceptive neural circuits and induction of pain hypersensitivity. Pericytes regulate capillary health and tone, with pericyte dysfunction in cerebral tissue associated with neurodegenerative disorders. Our work demonstrates that nociceptive processing is influenced by angiotensin II type 1 (AT1) receptor mediated pericyte contractility in the dorsal horn. Intravital imaging of the mouse spinal cord demonstrated angiotensin II induced cessation of spinal cord capillary perfusion. Intrathecal administration of angiotensin II induced pericyte contractility and narrowing of capillary diameter, which was accompanied by mechanical allodynia and heat hyperalgesia. Angiotensin II mediated pericyte activation and reduction of spinal cord blood flow, was prevented by inhibition of AT1 receptor via losartan treatment. In addition, losartan either systemically or intrathecally administered, prevented angiotensin II induced pain in male and female adult mice. This was associated with protection of the dorsal horn capillary endothelium, with intrathecal co-treatment with losartan preventing loss of CD31 immunoreactivity in the dorsal horn following administration of angiotensin II. This investigation demonstrates that AT1 mediated pericyte regulation of the dorsal horn capillary network, is fundamental in modulating nociceptive processing and perception of pain. Here we identify a novel cellular and mechanistic target for the development of new analgesic.

neuroscience↗

bioRxiv2021

Quantifying spinal cord vascular permeability in the mouse using intravital imaging

Sensory perception and motor dexterity is coordinated by in part distinct anatomical centres in the spinal cord. Importantly the spinal cord is the first modulatory relay hub for coordinating sensory and motor inputs to allow control of an organisms response to a sensory experience and to orientate proprioceptive outputs. This is whilst communicating with higher centres within the brain to undertake greater complex neurophysiological function such as pain perception. This begins to outline the complexity of the nervous system communication. To allow this integral system to function efficiently neuronal homeostasis needs to be maintained with energy expenditure matched by proficient delivery of nutrients. This factor introduces the vascular system that extensively interacts in a multifaceted manner with differing aspects of the nervous system. Part of this multi-factoral interaction is through the heterogenic cellular makeup of the vascular network that delivers and modulates the molecular transport of such nutrients to spinal cord tissues, but also controlling penetration and migration of harmful pathogens and agents. Therefore the spinal cord is susceptible to any alterations in the microvessel integrity (e.g. vascular leakage) and/or function (e.g. cessated blood flow) of this vascular network, which principally occurs in times of pathology. Typically investigations into microvessel function have utilised histological and/or tracer based in-vivo assays. Methodologies such as evans blue extravasation have been used inconjunction with in-vitro cell biology assays such as transwell assays to determine microvessel integrity or function that only provides snapshots of developing vasculopathy. Adopting in-vivo imaging approaches, allow for real time functional measurements of the ongoing physiological function within the spinal cord, providing direct measurement of the vascular processes in play, including vascular architecture, blood flow and/or permeability. This technique in mouse allow for direct visualisation of cellular and/or mechanistic influence upon vascular function through utilising disease, transgenic and/or viral approaches. This combination of attributes allows for in depth real time understanding of the function of the vascular network within the spinal cord.

neuroscience↗

bioRxiv2021

Hypoxia induced carbonic anhydrase mediated dorsal horn sensory neuron activation and induction ofneuropathic pain

Neuropathic pain such as that seen in diabetes mellitus, results in part from central sensitisation in the spinal cord dorsal horn. However, the mechanisms responsible for such sensitisation remain unclear. There is evidence that disturbances in the integrity of the spinal vascular network can be a causative factor in the development of neuropathic pain. Here we show that reduced blood flow and vascularity of the dorsal horn leads to the onset of neuropathic pain. Using rodent models (type 1 diabetes and an inducible endothelial specific vascular endothelial growth factor receptor 2 knockout mouse) that result in degeneration of the endothelium in the dorsal horn we show that spinal cord vasculopathy results in nociceptive behavioural hypersensitivity. This also results in increased hypoxia in dorsal horn sensory neurons, depicted by increased expression of hypoxia markers hypoxia inducible factor 1, glucose transporter 3 and carbonic anhydrase 7. Furthermore, inducing hypoxia via intrathecal delivery of dimethyloxalylglycine leads to the activation of dorsal horn sensory neurons as well as mechanical and thermal hypersensitivity. This shows that hypoxic signalling induced by reduced vascularity results in increased hypersensitivity and pain. Inhibition of carbonic anhydrase activity, through intraperitoneal injection of acetazolamide, inhibited hypoxia induced pain behaviours. This investigation demonstrates that induction of a hypoxic microenvironment in the dorsal horn, as occurs in diabetes, is an integral process by which sensory neurons are activated to initiate neuropathic pain states. This leads to the conjecture that reversing hypoxia by improving spinal cord microvascular blood flow could reverse or prevent neuropathic pain.

neuroscience↗