Mucopolysaccharidosis type I (MPS I) is an inherited α-L-iduronidase (IDUA, I) deficiency in which glycosaminoglycan (GAG) accumulation causes progressive multisystem organ dysfunction, neurological ...impairment, and death. Current MPS I mouse models, based on a NOD/SCID (NS) background, are short-lived, providing a very narrow window to assess the long-term efficacy of therapeutic interventions. They also develop thymic lymphomas, making the assessment of potential tumorigenicity of human stem cell transplantation problematic. We therefore developed a new MPS I model based on a NOD/SCID/Il2rγ (NSG) background. This model lives longer than 1 year and is tumor-free during that time. NSG MPS I (NSGI) mice exhibit the typical phenotypic features of MPS I including coarsened fur and facial features, reduced/abnormal gait, kyphosis, and corneal clouding. IDUA is undetectable in all tissues examined while GAG levels are dramatically higher in most tissues. NSGI brain shows a significant inflammatory response and prominent gliosis. Neurological MPS I manifestations are evidenced by impaired performance in behavioral tests. Human neural and hematopoietic stem cells were found to readily engraft, with human cells detectable for at least 1 year posttransplantation. This new MPS I model is thus suitable for preclinical testing of novel pluripotent stem cell-based therapy approaches.
Activation of visceral nociceptors by inflammatory mediators contributes to visceral hypersensitivity and abdominal pain associated with many gastrointestinal disorders. Purine and pyrimidine ...nucleotides (e.g., ATP and UTP) are strongly implicated in this process following their release from epithelial cells during mechanical stimulation of the gut, and from immune cells during inflammation. Actions of ATP are mediated through both ionotropic P2X receptors and metabotropic P2Y receptors. P2X receptor activation causes excitation of visceral afferents; however, the impact of P2Y receptor activation on visceral afferents innervating the gut is unclear. Here we investigate the effects of stimulating P2Y receptors in isolated mouse colonic sensory neurons, and visceral nociceptor fibers in mouse and human nerve-gut preparations. Additionally, we investigate the role of Nav1.9 in mediating murine responses. The application of UTP (P2Y2 and P2Y4 agonist) sensitized colonic sensory neurons by increasing action potential firing to current injection and depolarizing the membrane potential. The application of ADP (P2Y1, P2Y12, and P2Y13 agonist) also increased action potential firing, an effect blocked by the selective P2Y1 receptor antagonist MRS2500. UTP or ADP stimulated afferents, including mouse and human visceral nociceptors, in nerve-gut preparations. P2Y1 and P2Y2 transcripts were detected in 80% and 56% of retrogradely labeled colonic neurons, respectively. Nav1.9 transcripts colocalized in 86% of P2Y1-positive and 100% of P2Y2-positive colonic neurons, consistent with reduced afferent fiber responses to UTP and ADP in Na(v)1.9(-/-) mice. These data demonstrate that P2Y receptor activation stimulates mouse and human visceral nociceptors, highlighting P2Y-dependent mechanisms in the generation of visceral pain during gastrointestinal disease.
The development of effective visceral analgesics free of deleterious gut-specific side effects is a priority. We aimed to develop a reproducible methodology to study visceral nociception in human ...tissue that could aid future target identification and drug evaluation.
Electrophysiological (single unit) responses of visceral afferents to mechanical (von Frey hair (VFH) and stretch) and chemical (bradykinin and ATP) stimuli were examined. Thus, serosal afferents (putative nociceptors) were used to investigate the effect of tegaserod, and transient receptor potential channel, vanilloid 4 (TRPV
) modulation on mechanical responses.
Two distinct afferent fibre populations, serosal (n=23) and muscular (n=21), were distinguished based on their differences in sensitivity to VFH probing and tissue stretch. Serosal units displayed sensitivity to key algesic mediators, bradykinin (6/14 units tested) and ATP (4/10), consistent with a role as polymodal nociceptors, while muscular afferents are largely insensitive to bradykinin (0/11) and ATP (1/10). Serosal nociceptor mechanosensitivity was attenuated by tegaserod (-20.8±6.9%, n=6, p<0.05), a treatment for IBS, or application of HC067047 (-34.9±10.0%, n=7, p<0.05), a TRPV
antagonist, highlighting the utility of the preparation to examine the mechanistic action of existing drugs or novel analgesics. Repeated application of bradykinin or ATP produced consistent afferent responses following desensitisation to the first application, demonstrating their utility as test stimuli to evaluate analgesic activity.
Functionally distinct subpopulations of human visceral afferents can be demonstrated and could provide a platform technology to further study nociception in human tissue.
Key points
Voltage‐gated sodium channels play a fundamental role in determining neuronal excitability.
Specifically, voltage‐gated sodium channel subtype NaV1.7 is required for sensing acute and ...inflammatory somatic pain in mice and humans but its significance in pain originating from the viscera is unknown.
Using comparative behavioural models evoking somatic and visceral pain pathways, we identify the requirement for NaV1.7 in regulating somatic (noxious heat pain threshold) but not in visceral pain signalling.
These results enable us to better understand the mechanisms underlying the transduction of noxious stimuli from the viscera, suggest that the investigation of pain pathways should be undertaken in a modality‐specific manner and help to direct drug discovery efforts towards novel visceral analgesics.
Voltage‐gated sodium channel NaV1.7 is required for acute and inflammatory pain in mice and humans but its significance for visceral pain is unknown. Here we examine the role of NaV1.7 in visceral pain processing and the development of referred hyperalgesia using a conditional nociceptor‐specific NaV1.7 knockout mouse (NaV1.7Nav1.8) and selective small‐molecule NaV1.7 antagonist PF‐5198007. NaV1.7Nav1.8 mice showed normal nociceptive behaviours in response to intracolonic application of either capsaicin or mustard oil, stimuli known to evoke sustained nociceptor activity and sensitization following tissue damage, respectively. Normal responses following induction of cystitis by cyclophosphamide were also observed in both NaV1.7Nav1.8 and littermate controls. Loss, or blockade, of NaV1.7 did not affect afferent responses to noxious mechanical and chemical stimuli in nerve–gut preparations in mouse, or following antagonism of NaV1.7 in resected human appendix stimulated by noxious distending pressures. However, expression analysis of voltage‐gated sodium channel α subunits revealed NaV1.7 mRNA transcripts in nearly all retrogradely labelled colonic neurons, suggesting redundancy in function. By contrast, using comparative somatic behavioural models we identify that genetic deletion of NaV1.7 (in NaV1.8‐expressing neurons) regulates noxious heat pain threshold and that this can be recapitulated by the selective NaV1.7 antagonist PF‐5198007. Our data demonstrate that NaV1.7 (in NaV1.8‐expressing neurons) contributes to defined pain pathways in a modality‐dependent manner, modulating somatic noxious heat pain, but is not required for visceral pain processing, and advocate that pharmacological block of NaV1.7 alone in the viscera may be insufficient in targeting chronic visceral pain.
Key points
Voltage‐gated sodium channels play a fundamental role in determining neuronal excitability.
Specifically, voltage‐gated sodium channel subtype NaV1.7 is required for sensing acute and inflammatory somatic pain in mice and humans but its significance in pain originating from the viscera is unknown.
Using comparative behavioural models evoking somatic and visceral pain pathways, we identify the requirement for NaV1.7 in regulating somatic (noxious heat pain threshold) but not in visceral pain signalling.
These results enable us to better understand the mechanisms underlying the transduction of noxious stimuli from the viscera, suggest that the investigation of pain pathways should be undertaken in a modality‐specific manner and help to direct drug discovery efforts towards novel visceral analgesics.
NaV1.9 regulates normal colonic afferent mechanosensation and is required for hypersensitivity to noxious inflammatory mediators and those derived from inflammatory bowel disease tissues.
Chronic ...visceral pain affects millions of individuals worldwide and remains poorly understood, with current therapeutic options constrained by gastrointestinal adverse effects. Visceral pain is strongly associated with inflammation and distension of the gut. Here we report that the voltage-gated sodium channel subtype NaV1.9 is expressed in half of gut-projecting rodent dorsal root ganglia sensory neurons. We show that NaV1.9 is required for normal mechanosensation, for direct excitation and for sensitization of mouse colonic afferents by mediators from inflammatory bowel disease tissues, and by noxious inflammatory mediators individually. Excitatory responses to ATP or PGE2 were substantially reduced in NaV1.9−/− mice. Deletion of NaV1.9 substantially attenuates excitation and subsequent mechanical hypersensitivity after application of inflammatory soup (IS) (bradykinin, ATP, histamine, PGE2, and 5HT) to visceral nociceptors located in the serosa and mesentery. Responses to mechanical stimulation of mesenteric afferents were also reduced by loss of NaV1.9, and there was a rightward shift in stimulus–response function to ramp colonic distension. By contrast, responses to rapid, high-intensity phasic distension of the colon are initially unaffected; however, run-down of responses to repeat phasic distension were exacerbated in NaV1.9−/− afferents. Finally colonic afferent activation by supernatants derived from inflamed human tissue was greatly reduced in NaV1.9−/− mice. These results demonstrate that NaV1.9 is required for persistence of responses to intense mechanical stimulation, contributes to inflammatory mechanical hypersensitivity, and is essential for activation by noxious inflammatory mediators, including those from diseased human bowel. These observations indicate that NaV1.9 represents a high-value target for development of visceral analgesics.
Genomic screening is routinely used to guide the treatment of cancer patients in many countries. However, several multi-layered factors make this effort difficult to deliver within a clinically ...relevant timeframe. Here we share the learnings from the CRUK-funded Stratified Medicine Programme for advanced NSCLC patients, which could be useful to better plan future studies.
The ability to sense visceral pain during appendicitis is diminished with age leading to delay in seeking health care and poorer clinical outcomes. To understand the mechanistic basis of this ...phenomenon, we examined visceral nociception in aged mouse and human tissue. Inflamed and noninflamed appendixes were collected from consenting patients undergoing surgery for the treatment of appendicitis or bowel cancer. Supernatants were generated by incubating samples in buffer and used to stimulate multiunit activity in intestinal preparations, or single-unit activity from teased fibres in colonic preparations, of young and old mice. Changes in afferent innervation with age were determined by measuring the density of calcitonin gene-related peptide-positive afferent fibres and by counting dorsal root ganglia back-labelled by injection of tracer dye into the wall of the colon. Finally, the effect of age on nociceptor function was studied in mouse and human colon. Afferent responses to appendicitis supernatants were greatly impaired in old mice. Further investigation revealed this was due to a marked reduction in the afferent innervation of the bowel and a substantial impairment in the ability of the remaining afferent fibres to transduce noxious stimuli. Translational studies in human tissue demonstrated a significant reduction in the multiunit but not the single-unit colonic mesenteric nerve response to capsaicin with age, indicative of a loss of nociceptor innervation. Our data demonstrate that anatomical and functional deficits in nociception occur with age, underpinning the atypical or silent presentation of appendicitis in the elderly.
This study utilises an extensive set of sediment cores collected from a largely unstudied contourite and turbidite depositional system located on the Uruguay continental margin to identify a method ...of distinguishing deposits in the deep sea that are sourced from either gravity or bottom current sedimentary processes. The cores acquired by BG Group in 2014 targeted areas of the ocean floor that encompass both Late Pleistocene to Holocene age) large sediment drifts and large downslope canyons, where turbidite and contourite deposition occurs simultaneously. Core, sediment and micropalaeontological analysis has been used to answer three basic questions 1) Do the sediments collected from different geomorphic settings owe their origin to along-slope (contourite) or gravitational (turbidite) transport? 2) Do the drift sediments contain a record of palaeoceanographic change? and 3) Can micropalaeontologcial analysis resolve long-standing problems with differentiating along- and down-slope processes in the geological record. The presented study provides new data resolving these three questions for the upper, middle and lower Uruguayan slope. The new data comprises; 1. A detailed examination of the sedimentary facies of the (LatePleistocene to Holocene) Uruguay slope, while ground-truthing interpretations from seismic and bathymetric data collected from the same area that is broadly contemporaneous 2. A reconstruction of watermass migration using stable isotope, elemental ratios and foraminiferal indices accumulated on the Uruguay slope since the Last Glacial Maximum 3. A classification of foraminiferal assemblages for that are likely to be indicative of specific sedimentary facies in turbidite and contourite deposits in order to distinguish these facies from one another in a sedimentary environment where both contourite and turbidite deposition has occurred. This data elucidates some important new insights into the studied system and more broadly contourite and turbidite deposits globally: 1. A new model of mixed sedimentary system evolution on the Uruguay slope since the Last Glacial Maximum and how it is intrinsically linked to bottom-current/seafloor interactions 2. A new model for the flux of Antarctic sourced watermasses into the Atlantic basin across deglaciation 3. A new criterion for distinguishing contourites and from turbidite facies by using benthic foraminiferal ecological disturbance-succession patterns.
Key points * Voltage-gated sodium channels play a fundamental role in determining neuronal excitability. * Specifically, voltage-gated sodium channel subtype Na sub(V)1.7 is required for sensing ...acute and inflammatory somatic pain in mice and humans but its significance in pain originating from the viscera is unknown. * Using comparative behavioural models evoking somatic and visceral pain pathways, we identify the requirement for Na sub(V)1.7 in regulating somatic (noxious heat pain threshold) but not in visceral pain signalling. * These results enable us to better understand the mechanisms underlying the transduction of noxious stimuli from the viscera, suggest that the investigation of pain pathways should be undertaken in a modality-specific manner and help to direct drug discovery efforts towards novel visceral analgesics. Voltage-gated sodium channel Na sub(V)1.7 is required for acute and inflammatory pain in mice and humans but its significance for visceral pain is unknown. Here we examine the role of Na sub(V)1.7 in visceral pain processing and the development of referred hyperalgesia using a conditional nociceptor-specific Na sub(V)1.7 knockout mouse (Na sub(V)1.7 super(Nav1.8)) and selective small-molecule Na sub(V)1.7 antagonist PF-5198007. Na sub(V)1.7 super(Nav1.8) mice showed normal nociceptive behaviours in response to intracolonic application of either capsaicin or mustard oil, stimuli known to evoke sustained nociceptor activity and sensitization following tissue damage, respectively. Normal responses following induction of cystitis by cyclophosphamide were also observed in both Na sub(V)1.7 super(Nav1.8) and littermate controls. Loss, or blockade, of Na sub(V)1.7 did not affect afferent responses to noxious mechanical and chemical stimuli in nerve-gut preparations in mouse, or following antagonism of Na sub(V)1.7 in resected human appendix stimulated by noxious distending pressures. However, expression analysis of voltage-gated sodium channel alpha subunits revealed Na sub(V)1.7 mRNA transcripts in nearly all retrogradely labelled colonic neurons, suggesting redundancy in function. By contrast, using comparative somatic behavioural models we identify that genetic deletion of Na sub(V)1.7 (in Na sub(V)1.8-expressing neurons) regulates noxious heat pain threshold and that this can be recapitulated by the selective Na sub(V)1.7 antagonist PF-5198007. Our data demonstrate that Na sub(V)1.7 (in Na sub(V)1.8-expressing neurons) contributes to defined pain pathways in a modality-dependent manner, modulating somatic noxious heat pain, but is not required for visceral pain processing, and advocate that pharmacological block of Na sub(V)1.7 alone in the viscera may be insufficient in targeting chronic visceral pain. Key points * Voltage-gated sodium channels play a fundamental role in determining neuronal excitability. * Specifically, voltage-gated sodium channel subtype Na sub(V)1.7 is required for sensing acute and inflammatory somatic pain in mice and humans but its significance in pain originating from the viscera is unknown. * Using comparative behavioural models evoking somatic and visceral pain pathways, we identify the requirement for Na sub(V)1.7 in regulating somatic (noxious heat pain threshold) but not in visceral pain signalling. * These results enable us to better understand the mechanisms underlying the transduction of noxious stimuli from the viscera, suggest that the investigation of pain pathways should be undertaken in a modality-specific manner and help to direct drug discovery efforts towards novel visceral analgesics.
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