Planning experiments: Updated guidance on experimental design and analysis and their reporting III

Identification of arnicolide C as a novel chemosensitizer to suppress mTOR/E2F1/FANCD2 axis in non-small cell lung cancer

BACKGROUND AND PURPOSE

The mammalian target of rapamycin (mTOR) pathway plays critical roles in intrinsic chemoresistance by regulating Fanconi anaemia complementation group D2 (FANCD2) expression. However, the mechanisms by which mTOR regulates FANCD2 expression and related inhibitors are not clearly elucidated. Extracts of Centipeda minima (C. minima) showed promising chemosensitizing effects by inhibiting FANCD2 activity. Here, we have aimed to identify the bioactive chemosensitizer in C. minima extracts and elucidate its underlying mechanism.

EXPERIMENTAL APPROACH

The chemosensitizing effects of arnicolide C (ArC), a bioactive compound in C. minima, on non-small cell lung cancer (NSCLC) were investigated using immunoblotting, immunofluorescence, flow cytometry, the comet assay, small interfering RNA (siRNA) transfection and animal models. The online SynergyFinder software was used to determine the synergistic effects of ArC and chemotherapeutic drugs on NSCLC cells.

KEY RESULTS

ArC had synergistic cytotoxic effects with DNA cross-linking drugs such as cisplatin and mitomycin C in NSCLC cells. ArC treatment markedly decreased FANCD2 expression in NSCLC cells, thus attenuating cisplatin-induced FANCD2 nuclear foci formation, leading to DNA damage and apoptosis. ArC inhibited the mTOR pathway and attenuated mTOR-mediated expression of E2F1, a critical transcription factor of FANCD2. Co-administration of ArC and cisplatin exerted synergistic anticancer effects in the A549 xenograft mouse model by suppressing mTOR/FANCD2 signalling in tumour tissues.

CONCLUSION AND IMPLICATIONS

ArC suppressed DNA cross-linking drug-induced DNA damage response by inhibiting the mTOR/E2F1/FANCD2 signalling axis, serving as a chemosensitizing agent. This provides insight into the anticancer mechanisms of ArC and offers a potential combinatorial anticancer therapeutic strategy.

Trilobatin attenuates cerebral ischaemia/reperfusion-induced blood-brain barrier dysfunction by targeting matrix metalloproteinase 9: The legend of a food additive

BACKGROUND AND PURPOSE

Blood-brain barrier (BBB) breakdown is one of the crucial pathological changes of cerebral ischaemia-reperfusion (I/R) injury. Trilobatin (TLB), a naturally occurring food additive, exerts neuroprotective effects against cerebral I/R injury as demonstrated in our previous study. This study was designed to investigate the effect of TLB on BBB disruption after cerebral I/R injury.

EXPERIMENTAL APPROACH

Rats with focal cerebral ischaemia caused by transient middle cerebral artery occlusion were studied along with brain microvascular endothelial cells and human astrocytes to mimic BBB injury caused by oxygen and glucose deprivation/reoxygenation (OGD/R).

KEY RESULTS

The results showed that TLB effectively maintained BBB integrity and inhibited neuronal loss following cerebral I/R challenge. Furthermore, TLB increased tight junction proteins including ZO-1, Occludin and Claudin 5, and decreased the levels of apolipoprotein E (APOE) 4, cyclophilin A (CypA) and phosphorylated nuclear factor kappa B (NF-κB), thereby reducing proinflammatory cytokines. TLB also decreased the Bax/Bcl-2 ratio and cleaved-caspase 3 levels along with a reduced number of apoptotic neurons. Molecular docking and transcriptomics predicted MMP9 as a prominent gene evoked by TLB treatment. The protective effects of TLB on cerebral I/R-induced BBB breakdown was largely abolished by overexpression of MMP9, and the beneficial effects of TLB on OGD/R-induced loss of BBB integrity in human brain microvascular endothelial cells and astrocyte co-cultures was markedly reinforced by knockdown of MMP9.

CONCLUSIONS AND IMPLICATIONS

Our findings reveal a novel property of TLB: preventing BBB disruption following cerebral I/R via targeting MMP9 and inhibiting APOE4/CypA/NF-κB axis.

Meloxicam treatment disrupts the regional structure of innate inflammation sites by targeting the pro-inflammatory effects of prostanoids

BACKGROUND AND PURPOSE

Non-steroidal anti-inflammatory drugs (NSAIDs) are the most widely prescribed drugs in the world due to their analgesic, antipyretic and anti-inflammatory effects. However, NSAIDs inhibit prostanoid synthesis, interfering with their pro-inflammatory and anti-inflammatory functions and potentially prolonging acute inflammation.

EXPERIMENTAL APPROACH

We used high-content immunohistochemistry to define the impact of meloxicam treatment on spatially separated pro-inflammatory and anti-inflammatory processes during innate inflammation in mice induced by zymosan. This allowed us to determine the effect of meloxicam treatment on the organization of pro-inflammatory and anti-inflammatory microenvironments, thereby identifying relevant changes in immune cell localization, recruitment and activation.

KEY RESULTS

Meloxicam treatment reduced zymosan-induced thermal hypersensitivity at early time points but delayed its resolution. High-content immunohistochemistry revealed that the pro-inflammatory area was smaller after treatment, diminishing neutrophil recruitment, M1-like macrophage polarization, and especially phagocytosis by neutrophils and macrophages. The polarization of macrophages towards the M2-like anti-inflammatory phenotype was unaffected, and the number of anti-inflammatory eosinophils actually increased.

CONCLUSION AND IMPLICATIONS

High-content immunohistochemistry was able to identify relevant meloxicam-mediated effects on inflammatory processes based on alterations in the regional structure of inflammation sites. Meloxicam delayed the clearance of pathogens by inhibiting pro-inflammatory processes, causing prolonged inflammation. Our data suggest that the prescription of NSAIDs as a treatment during an acute pathogen-driven inflammation should be reconsidered in patients with compromised immune systems.

Development of a therapeutic monoclonal antibody against circulating adipocyte fatty acid binding protein to treat ischaemic stroke

BACKGROUND AND PURPOSE

Adipocyte fatty acid-binding protein (A-FABP) exacerbates cerebral ischaemia injury by disrupting the blood-brain barrier (BBB) through inducing expression of MMP-9. Circulating A-FABP levels positively correlate with infarct size in stroke patients. We hypothesized that targeting circulating A-FABP by a neutralizing antibody would alleviate ischaemic stroke outcome.

EXPERIMENTAL APPROACH

Monoclonal antibodies (mAbs) against A-FABP were generated using mouse hybridoma techniques. Binding affinities of a generated mAb named 6H2 towards various FABPs were determined using Biacore. Molecular docking studies were performed to characterize the 6H2-A-FABP complex structure and epitope. The therapeutic potential and safety of 6H2 were evaluated in mice with transient middle cerebral artery occlusion (MCAO) and healthy mice, respectively.

KEY RESULTS

Replenishment of recombinant A-FABP exaggerated the stroke outcome in A-FABP-deficient mice. 6H2 exhibited nanomolar to picomolar affinities to human and mouse A-FABP, respectively, with minimal cross-reactivities with heart and epidermal FABPs. 6H2 effectively neutralized JNK/c-Jun activation elicited by A-FABP and reduced MMP-9 production in macrophages. Molecular docking suggested that 6H2 interacts with the "lid" of the fatty acid binding pocket of A-FABP, thus likely hindering the binding of its substrates. In mice with transient MCAO, 6H2 significantly attenuated BBB disruption, cerebral oedema, infarction, neurological deficits, and decreased mortality associated with reduced cytokine and MMP-9 production. Chronic 6H2 treatment showed no obvious adverse effects in healthy mice.

CONCLUSION AND IMPLICATIONS

These results establish circulating A-FABP as a viable therapeutic target for ischaemic stroke, and provide a highly promising antibody drug candidate with high affinity and specificity.

Identification and pre-clinical investigation of 3-O-cyclohexanecarbonyl-11-keto-β-boswellic acid as a drug for external use to treat psoriasis

BACKGROUND AND PURPOSE

Psoriasis vulgaris is a refractory skin inflammatory disorder with 80% of the cases belonging to the mild-to-moderate type, which can be controlled by topical treatment. Nevertheless, the drugs for external use have not been upgraded for decades. We modified acetyl-11-keto-beta-boswellic acid (ABKA), a natural compound shown to treat psoriasis animal models, to improve efficacy and solubility for topical use.

EXPERIMENTAL APPROACH

Eleven compounds were synthesized using AKBA as a lead compound, and their effects on Th17 cell differentiation were screened. 3-O-cyclohexanecarbonyl-11-keto-β-boswellic acid (CKBA) potently inhibited Th17 cell differentiation. Its efficacy in a mouse model of psoriasis was assessed along with its pharmacology and safety profile when topically or systemically delivered to several animal species.

KEY RESULTS

CKBA inhibited mouse and human Th17 cell differentiation with an IC50 of 3.28 and 3.61 μM, respectively, and directly targeted acetyl-CoA carboxylase 1 (ACC1). Safety evaluation and toxicity tests suggested that systemically delivered high-dose CKBA for 14 days had no dose-associated adverse effects on the CNS, haematopoietic, cardiovascular, respiratory and digestive systems of cynomolgus monkeys. CKBA ointment permeated the skin and did not irritate or sensitize intact skin. CKBA ointment mediated dose-dependent suppression of imiquimod-induced psoriasis-like skin inflammation with slow absorption and limited bioavailability (<10% in rats and <1% in minipigs).

CONCLUSIONS AND IMPLICATIONS

CKBA is safe when topically or systemically delivered to animals. The beneficial effects of CKBA ointment in a mouse model of psoriasis indicate that this is a promising drug candidate for further development as a treatment for psoriasis.

Druggable site near the upper vestibule determines the high affinity and P2X3 homotrimer selectivity of sivopixant/S-600918 and its analogue DDTPA

BACKGROUND AND PURPOSE

The P2X3 receptor, a trimeric ionotropic purinergic receptor, has emerged as a potential therapeutic target for refractory chronic cough (RCC). Nevertheless, gefapixant/AF-219, the only marketed P2X3 receptor antagonist, might lead taste disorders by modulating the human P2X2/3 (hP2X2/3) heterotrimer. Hence, in RCC drug development, compounds exhibiting strong affinity for the hP2X3 homotrimer and a weak affinity for the hP2X2/3 heterotrimer hold promise. An example of such a molecule is sivopixant/S-600918, a clinical Phase II RCC candidate with a reduced incidence of taste disturbance compared to gefapixant. Sivopixant and its analogue, (3-(4-([3-chloro-4-isopropoxyphenyl]amino)-3-(4-methylbenzyl)-2,6-dioxo-3,6-dihydro-1,3,5-triazin-1(2H)-yl)propanoic acid (DDTPA), exhibit both high affinity and high selectivity for hP2X3 homotrimers, compared with hP2X2/3 heterotrimers. The mechanism underlying the druggable site and its high selectivity remains unclear.

EXPERIMENTAL APPROACH

To analyse mechanisms that distinguish this drug candidate from other inhibitors of the P2X3 receptors we used a combination of chimera construction, site covalent occupation, metadynamics, mutagenesis and whole-cell recording.

KEY RESULTS

The high affinity and selectivity of sivopixant/DDTPA for hP2X3 receptors was determined by the tri-symmetric site located close to the upper vestibule. Substitution of only four amino acids inside the upper body domain of hP2X2 with those of hP2X3, enabled the hP2X2/3 heterotrimer to exhibit a similar level of apparent affinity for sivopixant/DDTPA as the hP2X3 homotrimer.

CONCLUSION AND IMPLICATIONS

From the receptor-ligand recognition perspective, we have elucidated the molecular basis of novel RCC clinical candidates' cough-suppressing properties and reduced side effects, offering a promising approach to the discovery of novel drugs that specifically target P2X3 receptors.

A partial agonist of PPARγ prevents paclitaxel-induced peripheral neuropathy in mice, by inhibiting neuroinflammation

BACKGROUND AND PURPOSE

Chemotherapy-induced peripheral neuropathy (CIPN) is a common side effect of paclitaxel, affecting 30-50% of patients. Increased survival and concern with patients' quality of life have encouraged the search for new tools to prevent paclitaxel-induced neuropathy. This study presents the glitazone 4-[(Z)-(2,4-dioxo-1,3-thiazolidin-5-ylidene)methyl]-N-phenylbenzene-sulfonamide (TZD-A1) as a partial agonist of peroxisome proliferator-activated receptor γ (PPARγ), its toxicological profile and effects on paclitaxel-induced CIPN in mice.

EXPERIMENTAL APPROACH

Interactions of TZD-A1 with PPARγ were analysed using in silico docking and in vitro reporter gene assays. Pharmacokinetics and toxicity were evaluated using in silico, in vitro and in vivo (C57Bl/6 mice) analyses. Effects of TZD-A1 on CIPN were investigated in paclitaxel-injected mice. Axonal and dorsal root ganglion damage, mitochondrial complex activity and cytokine levels, brain-derived neurotrophic factor (BDNF), nuclear factor erythroid 2-related factor 2 (Nrf2) and PPARγ, were also measured.

KEY RESULTS

Docking analysis predicted TZD-A1 interactions with PPARγ compatible with partial agonism, which were corroborated by in vitro reporter gene assays. Good oral bioavailability and safety profile of TZD-A1 were shown in silico, in vitro and in vivo. Paclitaxel-injected mice, concomitantly treated with TZD-A1 by i.p. or oral administration, exhibited decreased mechanical and thermal hypersensitivity, effects apparently mediated by inhibition of neuroinflammation and mitochondrial damage, through increasing Nrf2 and PPARγ levels, and up-regulating BDNF.

CONCLUSION AND IMPLICATIONS

TZD-A1, a partial agonist of PPARγ, provided neuroprotection and reduced hypersensitivity induced by paclitaxel. Allied to its safety profile and good bioavailability, TZD-A1 is a promising drug candidate to prevent and treat CIPN in cancer patients.

Thromboxane A2/thromboxane A2 receptor axis facilitates hepatic insulin resistance and steatosis through endoplasmic reticulum stress in non-alcoholic fatty liver disease

BACKGROUND AND PURPOSE

Defective insulin signalling and dysfunction of the endoplasmic reticulum (ER), driven by excessive lipid accumulation in the liver, is a characteristic feature in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Thromboxane A2 (TXA2 ), an arachidonic acid metabolite, is significantly elevated in obesity and plays a crucial role in hepatic gluconeogenesis and adipose tissue macrophage polarization. However, the role of liver TXA2 /TP receptors in insulin resistance and lipid metabolism is largely unknown.

EXPERIMENTAL APPROACH

TP receptor knockout (TP-/- ) mice were generated and fed a high-fat diet for 16 weeks. Insulin sensitivity, ER stress responses and hepatic lipid accumulation were assessed. Furthermore, we used primary hepatocytes to dissect the mechanisms by which the TXA2 /TP receptor axis regulates insulin signalling and hepatocyte lipogenesis.

KEY RESULTS

TXA2 was increased in diet-induced obese mice, and depletion of TP receptors in adult mice improved systemic insulin resistance and hepatic steatosis. Mechanistically, we found that the TXA2 /TP receptor axis disrupts insulin signalling by activating the Ca2+ /calcium calmodulin-dependent kinase II γ (CaMKIIγ)-protein kinase RNA-like endoplasmic reticulum kinase (PERK)-C/EBP homologous protein (Chop)-tribbles-like protein 3 (TRB3) axis in hepatocytes. In addition, our results revealed that the TXA2 /TP receptor axis directly promoted lipogenesis in primary hepatocytes and contributed to Kupffer cell inflammation.

CONCLUSIONS AND IMPLICATIONS

The TXA2 /TP receptor axis facilitates insulin resistance through Ca2+ /CaMKIIγ to activate PERK-Chop-TRB3 signalling. Inhibition of hepatocyte TP receptors improved hepatic steatosis and inflammation. The TP receptor is a new therapeutic target for NAFLD and metabolic syndrome.

Formation and clearance of TNF-TNF inhibitor complexes during TNF inhibitor treatment

BACKGROUND AND PURPOSE

Millions of patients with inflammatory diseases are treated with tumour necrosis factor (TNF) inhibitors (TNFi). Individual treatment response varies, in part related to variable drug clearance. The role of TNF-TNFi complexes in clearance of the different TNFi is controversial. Moreover, mechanistic insight into the structural aspects and biological significance of TNF-TNFi complexes is lacking. We hypothesized a role for Fc-mediated clearance of TNF-TNFi immune complexes. Therefore, we investigated circulating TNF-TNFi complexes upon treatment with certolizumab-lacking Fc tails-in comparison with adalimumab, golimumab, infliximab and etanercept.

EXPERIMENTAL APPROACH

Drug-tolerant ELISAs were developed and used to quantify TNF during adalimumab, golimumab, etanercept, certolizumab and infliximab treatment in patients with inflammatory arthritis or ulcerative colitis for a maximum follow-up of 1 year. Effects on in vitro TNF production and Fc-mediated uptake of TNF-TNFi complexes were investigated for all five TNFi.

KEY RESULTS

Circulating TNF concentrations were >20-fold higher during certolizumab treatment compared with adalimumab, reaching up to 23.1 ng·ml-1 . Internalization of TNF-TNFi complexes by macrophages depended on Fc valency, with efficient uptake for the full antibody TNFi (three Fc tails), but little or no uptake for etanercept and certolizumab (one and zero Fc tail, respectively). TNF production was not affected by TNFi. Total TNF load did not affect clearance rate of total TNFi.

CONCLUSIONS AND IMPLICATIONS

Differences in TNFi structure profoundly affect clearance of TNF, while it is unlikely that TNF itself significantly contributes to target-mediated drug disposition of TNFi.

Flucloxacillin worsens while imipenem-cilastatin protects against vancomycin-induced kidney injury in a translational rat model

BACKGROUND AND PURPOSE

Vancomycin is one of the most common clinical antibiotics, yet acute kidney injury is a major limiting factor. Common combinations of antibiotics with vancomycin have been reported to worsen and improve vancomycin-induced kidney injury. We aimed to study the impact of flucloxacillin and imipenem-cilastatin on kidney injury when combined with vancomycin in our translational rat model.

EXPERIMENTAL APPROACH

Male Sprague-Dawley rats received allometrically scaled (1) vancomycin, (2) flucloxacillin, (3) vancomycin + flucloxacillin, (4) vancomycin + imipenem-cilastatin or (5) saline for 4 days. Kidney injury was evaluated via drug accumulation and urinary biomarkers including urinary output, kidney injury molecule-1 (KIM-1), clusterin and osteopontin. Relationships between vancomycin accumulation in the kidney and urinary kidney injury biomarkers were explored.

KEY RESULTS

Urinary output increased every study day for vancomycin + flucloxacillin, but after the first dose only in the vancomycin group. In the vancomycin + flucloxacillin group, urinary KIM-1 increased on all days compared with vancomycin. In the vancomycin + imipenem-cilastatin group, urinary KIM-1 was decreased on Days 1 and 2 compared with vancomycin. Similar trends were observed for clusterin. More vancomycin accumulated in the kidney with vancomycin + flucloxacillin compared with vancomycin and vancomycin + imipenem-cilastatin. The accumulation of vancomycin in the kidney tissue correlated with increasing urinary KIM-1.

CONCLUSIONS AND IMPLICATIONS

Vancomycin + flucloxacillin caused more kidney injury compared with vancomycin alone and vancomycin + imipenem-cilastatin in a translational rat model. The combination of vancomycin + imipenem-cilastatin was nephroprotective.

Astrocyte-derived lactoferrin reduces β-amyloid burden by promoting the interaction between p38 kinase and PP2A phosphatase in male APP/PS1 transgenic mice

BACKGROUND AND PURPOSE

Overexpression of astrocytic lactoferrin (Lf) was observed in the brain of Alzheimer's disease (AD) patients, whereas the role of astrocytic Lf in AD progression remains unexplored. In this study, we aimed to evaluate the effects of astrocytic Lf on AD progression.

EXPERIMENTAL APPROACH

Male APP/PS1 mice with astrocytes overexpressing human Lf were developed to evaluate the effects of astrocytic Lf on AD progression. N2a-sw cells also were employed to further uncover the mechanism of astrocytic Lf on β-amyloid (Aβ) production.

KEY RESULTS

Astrocytic Lf overexpression increased protein phosphatase 2A (PP2A) activity and reduced amyloid precursor protein (APP) phosphorylation, Aβ burden and tau hyperphosphorylation in APP/PS1 mice. Mechanistically, astrocytic Lf overexpression promoted the uptake of astrocytic Lf into neurons in APP/PS1 mice, and conditional medium from astrocytes overexpressing Lf inhibited p-APP (Thr668) expression in N2a-sw cells. Furthermore, recombinant human Lf (hLf) significantly enhanced PP2A activity and inhibited p-APP expression, whereas inhibition of p38 or PP2A activities abrogated the hLf-induced p-APP down-regulation in N2a-sw cells. Additionally, hLf promoted the interaction of p38 and PP2A via p38 activation, thereby enhancing PP2A activity, and low-density lipoprotein receptor-related protein 1 (LRP1) knockdown significantly reversed the hLf-induced p38 activation and p-APP down-regulation.

CONCLUSIONS AND IMPLICATIONS

Our data suggested that astrocytic Lf promoted neuronal p38 activation, via targeting to LRP1, subsequently promoting p38 binding to PP2A to enhance PP2A enzyme activity, which finally inhibited Aβ production via APP dephosphorylation. In conclusion, promoting astrocytic Lf expression may be a potential strategy against AD.

LINKED ARTICLES

This article is part of a themed issue From Alzheimer's Disease to Vascular Dementia: Different Roads Leading to Cognitive Decline. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.6/issuetoc.

Hsp70-Bim incoherent feedforward loop contributes to cell-fate heterogeneity and fractional killing

BACKGROUND AND PURPOSE

Although chemotherapeutics or molecular targeted drugs often elicit profound initial responses, fractional killing capable of driving acquired resistance can persist. Identifying stress-induced negative feedback or an incoherent feedforward loop (IFFL), which may contribute to fractional killing, is urgently needed.

EXPERIMENTAL APPROACH

Mathematical modelling was used to identify how and to what extent a recently reported Hsp70-Bim protein-protein interaction (PPI) contributes to the adaptation of the Bcl-2 network. Experimental validation was made by using a specific inhibitor of Hsp70-Bim PPI, S1g-2, as chemical tool. Bifurcation analysis and stochastic simulation were used for the theoretical study of the impact of Hsp70-Bim PPI on cell-fate heterogeneity and factional killing.

KEY RESULTS

The Hsp70-Bim-AKT circuit forms an IFFL that greatly contributes to the adaptation of the Bcl-2-regulated apoptosis network, thus leading to fractional killing. This adaptive programme enhances noise-induced cell-fate heterogeneity by shifting from a saddle-node to a saddle-collision transition scenario.

CONCLUSION AND IMPLICATIONS

Hsp70-Bim IFFL serves as a molecular pathway induced by DNA damaging drugs or tyrosine kinase inhibitors that enabled fractional killing, whereby acquired resistance emerges. A synergistic strategy is unveiled for overcoming fractional killing by suppressing Hsp70-Bim PPI.

Identification of a human blood biomarker of pharmacological 11β-hydroxysteroid dehydrogenase 1 inhibition

BACKGROUND AND PURPOSE

11β-Hydroxysteroid dehydrogenase-1 (11β-HSD1) catalyses the oxoreduction of cortisone to cortisol, amplifying levels of active glucocorticoids. It is a pharmaceutical target in metabolic disease and cognitive impairments. 11β-HSD1 also converts some 7oxo-steroids to their 7β-hydroxy forms. A recent study in mice described the ratio of tauroursodeoxycholic acid (TUDCA)/tauro-7oxolithocholic acid (T7oxoLCA) as a biomarker for decreased 11β-HSD1 activity. The present study evaluates the equivalent bile acid ratio of glycoursodeoxycholic acid (GUDCA)/glyco-7oxolithocholic acid (G7oxoLCA) as a biomarker for pharmacological 11β-HSD1 inhibition in humans and compares it with the currently applied urinary (5α-tetrahydrocortisol + tetrahydrocortisol)/tetrahydrocortisone ((5αTHF + THF)/THE) ratio.

EXPERIMENTAL APPROACH

Bile acid profiles were analysed by ultra-HPLC tandem-MS in blood samples from two independent, double-blind placebo-controlled clinical studies of the orally administered selective 11β-HSD1 inhibitor AZD4017. The blood GUDCA/G7oxoLCA ratio was compared with the urinary tetrahydro-glucocorticoid ratio for ability to detect 11β-HSD1 inhibition.

KEY RESULTS

No significant alterations were observed in bile acid profiles following 11β-HSD1 inhibition by AZD4017, except for an increase of the secondary bile acid G7oxoLCA. The enzyme product/substrate ratio GUDCA/G7oxoLCA was found to be more reliable to detect 11β-HSD1 inhibition than the absolute G7oxoLCA concentration in both cohorts. Comparison of the blood GUDCA/G7oxoLCA ratio with the urinary (5αTHF + THF)/THE ratio revealed that both successfully detect 11β-HSD1 inhibition.

CONCLUSIONS AND IMPLICATIONS

11β-HSD1 inhibition does not cause major alterations in bile acid homeostasis. The GUDCA/G7oxoLCA ratio represents the first blood biomarker of pharmacological 11β-HSD1 inhibition and may replace or complement the urinary (5αTHF + THF)/THE ratio biomarker.

Astragalus polysaccharide protects experimental colitis through an aryl hydrocarbon receptor-dependent autophagy mechanism

BACKGROUND AND PURPOSE

Disruption of intestinal barriers plays a vital role in the pathogenesis of colitis. The aryl hydrocarbon receptor (AhR) is a recognition sensor that mediates intestinal immune homeostasis and minimizes intestinal inflammation. Astragalus polysaccharide (APS) exerts pharmacological actions in colitis; however, the mechanism has not been elucidated. We investigated whether APS protects through AhR-dependent autophagy.

EXPERIMENTAL APPROACH

The symptoms of dextran sulfate sodium (DSS)-induced colitis in mice involving intestinal barrier function and inflammatory injury were evaluated after APS administration. Intestinal-specific Becn1 conditional knockout (Becn1 cKO) mice were constructed and compared with wild-type mice. Autophagy and the effects of APS were investigated after the deactivation of AhRs. The relationship between APS-induced AhRs and autophagic Becn1 was investigated using a dual-luciferase reporter system and chromatin immunoprecipitation (ChIP)-quantitative polymerase chain reaction assay. Caco-2 cells were used to investigate inflammatory responses and AhR-dependent autophagy.

KEY RESULTS

APS improved intestinal barrier function in inflammatory injury in colitis mice. APS triggered autophagic flow; however, knockout of Becn1 in the gut increased susceptibility to colitis, leading to diminished epithelial barrier function and severe intestinal inflammation, impairing the protective effects of APS. Mechanistically, APS-triggered autophagy depends on AhR expression. Activated AhR binds to the promoter Becn1 to operate transcription of genes involved in anti-inflammation and intestinal barrier repair, while deactivation of AhR correlated with intestinal inflammation and the therapeutic function of APS.

CONCLUSIONS AND IMPLICATIONS

APS protects colitis mice by targeting autophagy, especially as the AhR stimulates the repair of damaged intestinal barrier functions.

Individual differences in GHB consumption in a new voluntary GHB self-administration model in outbred rats

BACKGROUND AND PURPOSE

The use of the recreational drug gamma-hydroxybutyric acid (GHB) has increased over the past decade, concomitantly leading to a higher incidence of GHB use disorder. Evidence-based treatment interventions are hardly available and cognitive effects of long-term GHB use remain elusive. In order to study the development of GUD and the causal effects of chronic GHB consumption, a GHB self-administration model is required.

EXPERIMENTAL APPROACH

Long Evans rats had access to GHB in their home cage according to a two-bottle choice procedure for 3 months. Intoxication and withdrawal symptoms were assessed using an automated sensor-based setup for longitudinal behavioral monitoring. Rats were trained in an operant environment according to a fixed ratio (FR) 1, 2, and 4 schedule of reinforcement. Addiction-like behaviors were assessed through progressive ratio-, non-reinforced-, and quinine-adulterated operant tests. In addition, the novel object recognition test and elevated plus maze test were performed before and after GHB self-administration to assess memory performance and anxiety-like behavior, respectively.

KEY RESULTS

All rats consumed pharmacologically relevant levels of GHB in their home cage, and their intake remained stable over a period of 3 months. No clear withdrawal symptoms were observed following abstinence. Responding under operant conditions was characterized by strong inter-individual differences, where only a subset of rats showed high motivation for GHB, habitual GHB-seeking, and/or continued responding for GHB despite an aversive taste. Male rats showed a reduction in long-term memory performance 3 months after home-cage GHB self-administration. Anxiety-like behavior was not affected by GHB self-administration.

CONCLUSION AND IMPLICATIONS

The GHB self-administration model was able to reflect individual susceptibility for addiction-like behavior. The reduction in long-term memory performance upon GHB self-administration calls for further research into the cognitive effects of chronic GHB use in humans.

RALY participates in nerve trauma-induced nociceptive hypersensitivity through triggering Eif4g2 gene expression in primary sensory neurons

BACKGROUND AND PURPOSE

Peripheral nerve trauma-induced dysregulation of pain-associated genes in the primary sensory neurons of dorsal root ganglion (DRG) contributes to neuropathic pain genesis. RNA-binding proteins participate in gene transcription. We hypothesized that RALY, an RNA-binding protein, participated in nerve trauma-induced dysregulation of DRG pain-associated genes and nociceptive hypersensitivity.

METHODS AND RESULTS

Immunohistochemistry staining showed that RALY was expressed exclusively in the nuclei of DRG neurons. Peripheral nerve trauma caused by chronic constriction injury (CCI) of unilateral sciatic nerve produced time-dependent increases in the levels of Raly mRNA and RALY protein in injured DRG. Blocking this increase through DRG microinjection of adeno-associated virus 5 (AAV5)-expressing Raly shRNA reduced the CCI-induced elevation in the amount of eukaryotic initiation factor 4 gamma 2 (Eif4g2) mRNA and Eif4g2 protein in injured DRG and mitigated the development and maintenance of CCI-induced nociceptive hypersensitivity, without altering basal (acute) response to noxious stimuli and locomotor activity. Mimicking DRG increased RALY through DRG microinjection of AAV5 expressing Raly mRNA up-regulated the expression of Eif4g2 mRNA and Eif4g2 protein in the DRG and led to hypersensitive responses to noxious stimuli in the absence of nerve trauma. Mechanistically, CCI promoted the binding of RALY to the promoter of Eif4g2 gene and triggered its transcriptional activity.

CONCLUSION AND IMPLICATIONS

Our findings indicate that RALY participates in nerve trauma-induced nociceptive hypersensitivity likely through transcriptionally triggering Eif4g2 expression in the DRG. RALY may be a potential target in neuropathic pain management.

Complement tunes glutamate release and supports synaptic impairments in an animal model of multiple sclerosis

BACKGROUND AND PURPOSE

To deepen our knowledge of the role of complement in synaptic impairment in experimental autoimmune encephalomyelitis (EAE) mice, we investigated the distribution of C1q and C3 proteins and the role of complement as a promoter of glutamate release in purified nerve endings (synaptosomes) and astrocytic processes (gliosomes) isolated from the cortex of EAE mice at the acute stage of the disease (21 ± 1 day post-immunization).

EXPERIMENTAL APPROACH

EAE cortical synaptosomes and gliosomes were analysed for glutamate release efficiency (measured as release of preloaded [3 H]D-aspartate ([3 H]D-ASP)), C1q and C3 protein density, and for viability and ongoing apoptosis.

KEY RESULTS

In healthy mice, complement releases [3 H]D-ASP from gliosomes more efficiently than from synaptosomes. The releasing activity occurs in a dilution-dependent manner and involves the reversal of the excitatory amino acid transporters (EAATs). In EAE mice, the complement-induced releasing activity is significantly reduced in cortical synaptosomes but amplified in cortical gliosomes. These adaptations are paralleled by decreased density of the EAAT2 protein in synaptosomes and increased EAAT1 staining in gliosomes. Concomitantly, PSD95, GFAP, and CD11b, but not SNAP25, proteins are overexpressed in the cortex of the EAE mice. Similarly, C1q and C3 protein immunostaining is increased in EAE cortical synaptosomes and gliosomes, although signs of ongoing apoptosis or altered viability are not detectable.

CONCLUSION AND IMPLICATIONS

Our results unveil a new noncanonical role of complement in the CNS of EAE mice relevant to disease progression and central synaptopathy that suggests new therapeutic targets for the management of MS.

MicroRNA-guided drug discovery for mitigating persistent pulmonary complications in critical COVID-19 survivors: A longitudinal pilot study

BACKGROUND AND PURPOSE

The post-acute sequelae of SARS-CoV-2 infection pose a significant global challenge, with nearly 50% of critical COVID-19 survivors manifesting persistent lung abnormalities. The lack of understanding about the molecular mechanisms and effective treatments hampers their management. Here, we employed microRNA (miRNA) profiling to decipher the systemic molecular underpinnings of the persistent pulmonary complications.

EXPERIMENTAL APPROACH

We conducted a longitudinal investigation including 119 critical COVID-19 survivors. A comprehensive pulmonary evaluation was performed in the short-term (median = 94.0 days after hospital discharge) and long-term (median = 358 days after hospital discharge). Plasma miRNAs were quantified at the short-term evaluation using the gold-standard technique, RT-qPCR. The analyses combined machine learning feature selection techniques with bioinformatic investigations. Two additional datasets were incorporated for validation.

KEY RESULTS

In the short-term, 84% of the survivors exhibited impaired lung diffusion (DLCO  < 80% of predicted). One year post-discharge, 54.4% of this patient subgroup still presented abnormal DLCO . Four feature selection methods identified two specific miRNAs, miR-9-5p and miR-486-5p, linked to persistent lung dysfunction. The downstream experimentally validated targetome included 1473 genes, with heterogeneous enriched pathways associated with inflammation, angiogenesis and cell senescence. Validation studies using RNA-sequencing and proteomic datasets emphasized the pivotal roles of cell migration and tissue repair in persistent lung dysfunction. The repositioning potential of the miRNA targets was limited.

CONCLUSION AND IMPLICATIONS

Our study reveals early mechanistic pathways contributing to persistent lung dysfunction in critical COVID-19 survivors, offering a promising approach for the development of targeted disease-modifying agents.

Licorice metabolite 18β-glycyrrhetinic acid activates G protein-gated inwardly rectifying K+ channels

BACKGROUND AND PURPOSE

Licorice (liquorice) is a common food additive and is used in Chinese medicine. Excess licorice intake can induce atrial fibrillation. Patients with atrial fibrillation possess constitutively activated G protein-gated inwardly rectifying K+ (GIRK) channels. Whether licorice affects GIRK channel activity is unknown. We aimed to clarify the effects of licorice ingredients on GIRK current and the mechanism of action.

EXPERIMENTAL APPROACH

A major component of licorice, glycyrrhizic acid (GA), and its metabolite, 18β-glycyrrhetinic acid (18β-GA), were tested. We performed electrophysiological recordings in Xenopus oocytes to examine the effects of GA and 18β-GA on various GIRK subunits (Kir 3.1-Kir 3.4), mutagenesis analyses to identify the crucial residues for drug action and motion analysis in cultured rat atrial myocytes to clarify effects of 18β-GA on atrial functions.

KEY RESULTS

GA inhibited Kir 3.1-containing channels, while 18β-GA activated all Kir 3.x subunits. A pore helix residue Phe137 in Kir 3.1 was critical for GA-mediated inhibition, and the corresponding Ser148 in Kir 3.2 was critical for 18β-GA-mediated activation. 18β-GA activated GIRK channel in a Gβγ -independent manner, whereas phosphatidylinositol 4,5-bisphosphate (PIP2 ) was essential for activation. Glu236 located at the cytoplasmic pore of Kir 3.2 appeared to be important to interactions with 18β-GA. In rat atrial myocytes, 18β-GA suppressed spontaneous beating via activation of GIRK channels.

CONCLUSION AND IMPLICATIONS

GA acts as a novel GIRK inhibitor, and 18β-GA acts as a novel GIRK activator. 18β-GA alters atrial function via activation of GIRK channels. This study elucidates the pharmacological activity of licorice ingredients and provides information for drug design.

Inhibition of p38MAPK signalling pathway alleviates radiation-induced testicular damage through improving spermatogenesis

BACKGROUND AND PURPOSE

Damage to the testis following exposure to ionizing radiation has become an urgent problem to be solved. Here we have investigated if inhibition of p38 mitogen-activated protein kinase (p38MAPK) signalling could alleviate radiation-induced testicular damage.

EXPERIMENTAL APPROACH

In mice exposed to whole body radiation (2-6 Gy), morphological changes of the epididymis and testis was measured by histochemical staining. immunohistochemical and immunofluorescence procedures and western blotting were used to monitor expression and cellular location of proteins. Expression of genes was assessed by qPCR and RNA-Seq was used to profile gene expression.

KEY RESULTS

Exposure to ionizing radiation induced dose-dependent damage to mouse testis. The sperm quality decreased at 6 and 8 weeks after 6 Gy X-ray radiation. Radiation decreased PLZF+ cells and increased SOX9+ cells, and affected the expression of 969 genes, compared with data from non-irradiated mice. Expression of genes related to p38MAPK were enriched by GO analysis and were increased in the irradiated testis, and confirmed by qPCR. Levels of phospho-p38MAPK protein increased at 28 days after irradiation. In irradiated mice, SB203580 treatment increased spermatozoa, SOX9+ cells, the area and diameter of seminiferous tubules, sperm movement rate and density. Furthermore, SB203580 treatment increased SCP3+ cells, accelerating the process of spermatogenesis.

CONCLUSION AND IMPLICATIONS

Exposure to ionizing radiation clearly changed gene expression in mouse testis, involving activation of p38MAPK signalling pathways. Inhibition of p38MAPK by SB203580 partly alleviated the testicular damage caused by radiation and accelerated the recovery of sperms through promoting spermatogenesis.

Targeted delivery of galunisertib using machine perfusion reduces fibrogenesis in an integrated ex vivo renal transplant and fibrogenesis model

BACKGROUND AND PURPOSE

Fibrosis in kidney allografts is a major post-transplant complication that contributes to graft failure. Lately, multiple potent inhibitors of fibrosis-related pathways have been developed such as galunisertib, an inhibitor of the transforming growth factor-beta (TGF-β/TGFβ1) signalling pathway. This drug, however, poses risks for adverse effects when administered systemically. Therefore, we devised a new repurposing strategy in which galunisertib is administered ex vivo. We combined machine perfusion and tissue slices to explore the antifibrotic effects of galunisertib in renal grafts.

EXPERIMENTAL APPROACH

Porcine kidneys were subjected to 30 min of warm ischaemia, 24 h of oxygenated hypothermic machine perfusion and 6 h of normothermic machine perfusion with various treatments (i.e. untreated control, TGFβ1, galunisertib or TGFβ1 + galunisertib; n = 8 kidneys per group). To determine whether effects persisted upon ceasing treatment, kidney slices were prepared from respective kidneys and incubated for 48 h.

KEY RESULTS

Galunisertib treatment improved general viability without negatively affecting renal function or elevating levels of injury markers or by-products of oxidative stress during perfusion. Galunisertib also reduced inflammation and, more importantly, reduced the onset of fibrosis after 48 h of incubation.

CONCLUSIONS AND IMPLICATIONS

Our findings demonstrate the value of using machine perfusion for administering antifibrotic drugs such as galunisertib, proving it to be an effective example of repurposing.

Pharmacological inhibition of the integrated stress response accelerates disease progression in an amyotrophic lateral sclerosis mouse model

BACKGROUND AND PURPOSE

The integrated stress response (ISR) regulates translation in response to diverse stresses. ISR activation has been documented in amyotrophic lateral sclerosis (ALS) patients and ALS experimental models. In experimental models, both ISR stimulation and inhibition prevented ALS neurodegeneration; however, which mode of ISR regulation would work in patients is still debated. We previously demonstrated that the ISR modulator ISRIB (Integrated Stress Response InhiBitor, an eIF2B activator) enhances survival of neurons expressing the ALS neurotoxic allele SOD1 G93A. Here, we tested the effect of two ISRIB-like eIF2B activators (2BAct and PRXS571) in the disease progression of transgenic SOD1G93A mice.

EXPERIMENTAL APPROACH

After biochemical characterization in primary neurons, SOD1G93A mice were treated with 2BAct and PRXS571. Muscle denervation of vulnerable motor units was monitored with a longitudinal electromyographic test. We used a clinical score to document disease onset and progression; force loss was determined with the hanging wire motor test. Motor neuronal survival was assessed by immunohistochemistry.

KEY RESULTS

In primary neurons, 2BAct and PRXS571 relieve the ISR-imposed translational inhibition while maintaining high ATF4 levels. Electromyographic recordings evidenced an earlier and more dramatic muscle denervation in treated SOD1G93A mice that correlated with a decrease in motor neuron survival. Both compounds anticipated disease onset and shortened survival time.

CONCLUSION AND IMPLICATIONS

2BAct and PRXS571 anticipate disease onset, aggravating muscle denervation and motor neuronal death of SOD1G93A mice. This study reveals that the ISR works as a neuroprotective pathway in ALS motor neurons and reveals the toxicity that eIF2B activators may display in ALS patients.

Stimulation of platelet P2Y1 receptors by different endogenous nucleotides leads to functional selectivity via biased signalling

BACKGROUND AND PURPOSE

Platelet function during inflammation is dependent on activation by endogenous nucleotides. Non-canonical signalling via the P2Y1 receptor is important for these non-thrombotic functions of platelets. However, apart from ADP, the role of other endogenous nucleotides acting as agonists at P2Y1 receptors is unknown. This study compared the effects of ADP, Ap3A, NAD+ , ADP-ribose, and Up4A on platelet functions contributing to inflammation or haemostasis.

EXPERIMENTAL APPROACH

Platelets obtained from healthy human volunteers were incubated with ADP, Ap3A, NAD+ , ADP-ribose, or Up4A, with aggregation and fibrinogen binding measured (examples of function during haemostasis) or before exposure to fMLP to measure platelet chemotaxis (an inflammatory function). In silico molecular docking of these nucleotides to the binding pocket of P2Y1 receptors was then assessed.

KEY RESULTS

Platelet aggregation and binding to fibrinogen induced by ADP was not mimicked by NAD+ , ADP-ribose, and Up4A. However, these endogenous nucleotides induced P2Y1 -dependent platelet chemotaxis, an effect that required RhoA and Rac-1 activity, but not canonical PLC activity. Analysis of molecular docking of the P2Y1 receptor revealed distinct differences of amino acid interactions and depth of fit within the binding pocket for Ap3A, NAD+ , ADP-ribose, or Up4A compared with ADP.

CONCLUSION AND IMPLICATIONS

Platelet function (aggregation vs motility) can be differentially modulated by biased-agonist activation of P2Y1 receptors. This may be due to the character of the ligand-binding pocket interaction. This has implications for future therapeutic strategies aimed to suppress platelet activation during inflammation without affecting haemostasis as is the requirement of current ant-platelet drugs.

LINKED ARTICLES

This article is part of a themed issue on Platelet purinergic receptor and non-thrombotic disease. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.4/issuetoc.

Dopamine regulates colonic glial cell-derived neurotrophic factor secretion through cholinergic dependent and independent pathways

BACKGROUND AND PURPOSE

Glial cell-derived neurotrophic factor (GDNF) maintains gut homeostasis. Dopamine promotes GDNF release in astrocytes. We investigated the regulation by dopamine of colonic GDNF secretion.

EXPERIMENTAL APPROACH

D1 receptor knockout (D1 R-/- ) mice, adeno-associated viral 9-short hairpin RNA carrying D2 receptor (AAV9-shD2 R)-treated mice, 6-hydroxydopamine treated (6-OHDA) rats and primary enteric glial cells (EGCs) culture were used. Incubation fluid from colonic submucosal plexus and longitudinal muscle myenteric plexus were collected for GDNF and ACh measurements.

KEY RESULTS

D2 receptor-immunoreactivity (IR), but not D1 receptor-IR, was observed on EGCs. Both D1 receptor-IR and D2 receptor-IR were co-localized on cholinergic neurons. Low concentrations of dopamine induced colonic GDNF secretion in a concentration-dependent manner, which was mimicked by the D1 receptor agonist SKF38393, inhibited by TTX and atropine and eliminated in D1 R-/- mice. SKF38393-induced colonic ACh release was absent in D1 R-/- mice. High concentrations of dopamine suppressed colonic GDNF secretion, which was mimicked by the D2 receptor agonist quinpirole, and absent in AAV-shD2 R-treated mice. Quinpirole decreased GDNF secretion by reducing intracellular Ca2+ levels in primary cultured EGCs. Carbachol ( ACh analogue) promoted the release of GDNF. Quinpirole inhibited colonic ACh release, which was eliminated in the AAV9-shD2 R-treated mice. 6-OHDA treated rats with low ACh and high dopamine content showed decreased GDNF content and increased mucosal permeability in the colon.

CONCLUSION AND IMPLICATIONS

Low concentrations of dopamine promote colonic GDNF secretion via D1 receptors on cholinergic neurons, whereas high concentrations of dopamine inhibit GDNF secretion via D2 receptors on EGCs and/or cholinergic neurons.

AhR-STAT3-HO-1/COX-2 signalling pathway may restrict ferroptosis and improve hMSC accumulation and efficacy in mouse liver

BACKGROUND AND PURPOSE

The low efficacy of mesenchymal stem cells (MSCs) has restricted their application in the treatment of liver disease. Emerging evidence suggested that ferroptosis may provoke hepatocyte dysfunction and exacerbate damage to the liver microenvironment. Here, we have investigated the contribution of liver ferroptosis to the elimination and effectiveness of human MSC (hMSC). Furthermore, potential links between liver ferroptosis and aryl hydrocarbon receptors (AhR) were explored.

EXPERIMENTAL APPROACH

Two mouse models, iron supplement-induced hepatic ferroptosis and hepatic ischaemia/reperfusion (I/R) injury, were used to identify effects of ferroptosis on hMSC pharmacokinetics (PK)/pharmacodynamics (PD).

KEY RESULTS

AhR inhibition attenuated hepatic ferroptosis and improved survival of hMSCs. hMSC viability was decreased by iron supplementation or serum from I/R mice. The AhR antagonist CH223191 reversed iron overload and oxidative stress induced by ferroptosis and increased hMSC concentration and efficacy in mouse models. Effects of CH223191 were greater than those of deferoxamine, a conventional ferroptosis inhibitor. Transcriptomic results suggested that the AhR-signal transducer and activator of transcription 3 (STAT3)-haem oxygenase 1/COX-2 signalling pathway is critical to this process. These results were confirmed in a mouse model of hepatic I/R injury. In mice pre-treated with CH223191, hMSC exhibited more potent protective effects, linked to decreased hepatic ferroptosis.

CONCLUSION AND IMPLICATIONS

Our findings showed that ferroptosis was a critical factor in determining the fate of hMSCs. Inhibition of AhR decreased hepatic ferroptosis, thereby increasing survival and therapeutic effects of hMSCs in mouse models of liver disease.

A novel EGFR inhibitor, HNPMI, regulates apoptosis and oncogenesis by modulating BCL-2/BAX and p53 in colon cancer

BACKGROUND AND PURPOSE

Colorectal cancer (CRC) is the second most lethal disease, with high mortality due to its heterogeneity and chemo-resistance. Here, we have focused on the epidermal growth factor receptor (EGFR) as an effective therapeutic target in CRC and studied the effects of polyphenols known to modulate several key signalling mechanisms including EGFR signalling, associated with anti-proliferative and anti-metastatic properties.

EXPERIMENTAL APPROACH

Using ligand- and structure-based cheminformatics, we developed three potent, selective alkylaminophenols, 2-[(3,4-dihydroquinolin-1(2H)-yl)(p-tolyl)methyl]phenol (THTMP), 2-[(1,2,3,4-tetrahydroquinolin-1-yl)(4-methoxyphenyl)methyl]phenol (THMPP) and N-[2-hydroxy-5-nitrophenyl(4'-methylphenyl)methyl]indoline (HNPMI). These alkylaminophenols were assessed for EGFR interaction, EGFR-pathway modulation, cytotoxic and apoptosis induction, caspase activation and transcriptional and translational regulation. The lead compound HNPMI was evaluated in mice bearing xenografts of CRC cells.

KEY RESULTS

Of the three alkylaminophenols tested, HNPMI exhibited the lowest IC50 in CRC cells and potential cytotoxic effects on other tumour cells. Modulation of EGFR pathway down-regulated protein levels of osteopontin, survivin and cathepsin S, leading to apoptosis. Cell cycle analysis revealed that HNPMI induced G0/G1 phase arrest in CRC cells. HNPMI altered the mRNA for and protein levels of several apoptosis-related proteins including caspase 3, BCL-2 and p53. HNPMI down-regulated the proteins crucial to oncogenesis in CRC cells. Assays in mice bearing CRC xenografts showed that HNPMI reduced the relative tumour volume.

CONCLUSIONS AND IMPLICATIONS

HNPMI is a promising EGFR inhibitor for clinical translation. HNPMI regulated apoptosis and oncogenesis by modulating BCL-2/BAX and p53 in CRC cell lines, showing potential as a therapeutic agent in the treatment of CRC.

Influence of Slco2b1-knockout and SLCO2B1-humanization on coproporphyrin I and III levels in rats

BACKGROUND AND PURPOSE

Coproporphyrin (CP) I and III are byproducts of haem synthesis currently investigated as biomarkers for drug-drug interactions involving hepatic organic anion transporting polypeptide (OATP) 1B transporters. Another hepatically expressed OATP-member is OATP2B1. The aim of this study was to test the impact of OATP2B1, which specifically transports CPIII, on CP serum levels, applying novel rat models.

EXPERIMENTAL APPROACH

CPIII transport kinetics and the interplay between OATP2B1 and multidrug resistance-associated proteins (MRPs) were determined in vitro using the vTF7 expression system. Novel rSlco2b1-/- and SLCO2B1+/+ rat models were characterized for physiological parameters and for CP serum levels. Hepatic and renal expression of transporters involved in CP disposition were determined by real-time qPCR, Western blot analysis, and immunohistochemistry.

KEY RESULTS

In vitro experiments revealed differences in transport kinetics comparing human and rat OATP2B1 and showed a consistent, species-specific interplay with hMRP3/rMRP3. Deletion of rOATP2B1 was associated with a trend towards lower CPI serum levels compared with wildtype rats, while CPIII remained unchanged. Comparing SLCO2B1+/+ with knockout rats revealed an effect of sex: only in females the genetic modification influenced CP serum levels. Analysis of hepatic and renal transporters revealed marginal, but in part, statistically significant differences in rMRP2 abundance, which may contribute to the observed changes in CP serum levels.

CONCLUSION AND IMPLICATIONS

Our findings support that factors other than OATP1B transporters are of relevance for basal CP levels. Only in female rats, humanization of SLCO2B1 affects basal CPI and CPIII serum levels, despite isomer selectivity of OATP2B1.

Ticagrelor inverse agonist activity at the P2Y12 receptor is non-reversible versus its endogenous agonist adenosine 5´-diphosphate

BACKGROUND AND PURPOSE

Ticagrelor is labelled as a reversible, direct-acting platelet P2Y12 receptor (P2Y12 R) antagonist that is indicated clinically for the prevention of thrombotic events in patients with acute coronary syndrome (ACS). As with many antiplatelet drugs, ticagrelor therapy increases bleeding risk in patients, which may require platelet transfusion in emergency situations. The aim of this study was to further examine the reversibility of ticagrelor at the P2Y12 R.

EXPERIMENTAL APPROACH

Studies were performed in human platelets, with P2Y12 R-stimulated GTPase activity and platelet aggregation assessed. Cell-based bioluminescence resonance energy transfer (BRET) assays were undertaken to assess G protein-subunit activation downstream of P2Y12 R activation.

KEY RESULTS

Initial studies revealed that a range of P2Y12 R ligands, including ticagrelor, displayed inverse agonist activity at P2Y12 R. Only ticagrelor was resistant to washout and, in human platelet and cell-based assays, washing failed to reverse ticagrelor-dependent inhibition of ADP-stimulated P2Y12 R function. The P2Y12 R agonist 2MeSADP, which was also resistant to washout, was able to effectively compete with ticagrelor. In silico docking revealed that ticagrelor and 2MeSADP penetrated more deeply into the orthosteric binding pocket of the P2Y12 R than other P2Y12 R ligands.

CONCLUSION AND IMPLICATIONS

Ticagrelor binding to P2Y12 R is prolonged and more akin to that of an irreversible antagonist, especially versus the endogenous P2Y12 R agonist ADP. This study highlights the potential clinical need for novel ticagrelor reversal strategies in patients with spontaneous major bleeding, and for bleeding associated with urgent invasive procedures.

Pharmacological characterisation of erenumab, Aimovig, at two calcitonin gene-related peptide responsive receptors

BACKGROUND AND PURPOSE

Calcitonin gene-related peptide (CGRP) is involved in migraine pathophysiology. CGRP can signal through two receptors. The canonical CGRP receptor comprises the calcitonin receptor-like receptor and receptor activity-modifying protein 1 (RAMP1); the AMY1 receptor comprises the calcitonin receptor with RAMP1. Drugs that reduce CGRP activity, such as receptor antagonists, are approved for the treatment and prevention of migraine. Despite being designed to target the canonical CGRP receptor, emerging evidence suggests that these antagonists, including erenumab (a monoclonal antibody antagonist) can also antagonise the AMY1 receptor. However, it is difficult to estimate its selectivity because direct comparisons between receptors under matched conditions have not been made. We therefore characterised erenumab at both CGRP-responsive receptors with multiple ligands, including αCGRP and βCGRP.

EXPERIMENTAL APPROACH

Erenumab antagonism was quantified through IC50 and pKB experiments, measuring cAMP production. We used SK-N-MC cells which endogenously express the human CGRP receptor, and HEK293S and Cos7 cells transiently transfected to express either human CGRP or AMY1 receptors.

KEY RESULTS

Erenumab antagonised both the CGRP and AMY1 receptors with an ~20-120-fold preference for the CGRP receptor, depending on the cells, agonist, analytical approach and/or assay format. Erenumab antagonised both forms of CGRP equally, and appeared to act as a competitive reversible antagonist at both receptors.

CONCLUSION AND IMPLICATIONS

Despite being designed to target the CGRP receptor, erenumab can antagonise the AMY1 receptor. Its ability to antagonise CGRP activity at both receptors may be useful in better understanding the clinical profile of erenumab.

Acetazolamide and topiramate lower intracranial pressure through differential mechanisms: The effect of acute and chronic administration

BACKGROUND AND PURPOSE

Diseases of raised intracranial pressure (ICP) cause severe morbidity and mortality. Multiple drugs are utilised to lower ICP including acetazolamide and topiramate. However, the evidence for their use is unclear. We aimed to assess the ICP modulatory effects and molecular effects at the choroid plexus (CP) of acetazolamide and topiramate.

EXPERIMENTAL APPROACH

Female rats were implanted with telemetric ICP probes for physiological, freely moving 24/7 ICP recordings. Randomised cross-over studies were performed, where rats received acute (24 h) high doses of acetazolamide and topiramate, and chronic (10 days) clinically equivalent doses of acetazolamide and topiramate, all via oral gavage. Cerebrospinal fluid (CSF) secretion assays, and RT-qPCR and western blots on in vitro and in vivo CP, were used to investigate drug actions.

KEY RESULTS

We demonstrate that acetazolamide and topiramate achieved maximal ICP reduction within 120 min of administration, and in combination doubled the ICP reduction over a 24-h period. Chronic administration of acetazolamide or topiramate lowered ICP by 25%. Topiramate decreased CSF secretion by 40%. Chronic topiramate increased the gene expression of Slc12a2 and Slc4a10 and protein expression of the sodium-dependent chloride/bicarbonate exchanger (NCBE), whereas chronic acetazolamide did not affect the expression of assessed genes.

CONCLUSIONS AND IMPLICATIONS

Acetazolamide and topiramate are effective at lowering ICP at therapeutic levels. We provide the first evidence that topiramate lowers CSF secretion and that acetazolamide and topiramate may lower ICP via distinct molecular mechanisms. Thus, the combination of acetazolamide and topiramate may have utility for treating raised ICP.

Orexin 2 receptor antagonism sex-dependently improves sleep/wakefulness and cognitive performance in tau transgenic mice

BACKGROUND AND PURPOSE

Tau pathology contributes to a bidirectional relationship between sleep disruption and neurodegenerative disease. Tau transgenic rTg4510 mice model tauopathy symptoms, including sleep/wake disturbances, which manifest as marked hyperarousal. This phenotype can be prevented by early transgene suppression; however, whether hyperarousal can be rescued after onset is unknown.

EXPERIMENTAL APPROACH

Three 8-week experiments were conducted with wild-type and rTg4510 mice after age of onset of hyperarousal (4.5 months): (1) Tau transgene suppression with doxycycline (200 ppm); (2) inactive phase rapid eye movement (REM) sleep enhancement with the dual orexin receptor antagonist suvorexant (50 mg·kg-1 ·day-1 ); or (3) Active phase non-NREM (NREM) and REM sleep enhancement using the selective orexin 2 (OX2 ) receptor antagonist MK-1064 (40 mg·kg-1 ·day-1 ). Sleep was assessed using polysomnography, cognition using the Barnes maze, and tau pathology using immunoblotting and/or immunohistochemistry.

KEY RESULTS

Tau transgene suppression improved tauopathy and hippocampal-dependent spatial memory, but did not modify hyperarousal. Pharmacological rescue of REM sleep deficits did not improve spatial memory or tau pathology. In contrast, normalising hyperarousal by increasing both NREM and REM sleep via OX2 receptor antagonism restored spatial memory, independently of tauopathy, but only in male rTg4510 mice. OX2 receptor antagonism induced only short-lived hypnotic responses in female rTg4510 mice and did not improve spatial memory, indicating a tau- and sex-dependent disruption of OX2 receptor signalling.

CONCLUSIONS AND IMPLICATIONS

Pharmacologically reducing hyperarousal corrects tau-induced sleep/wake and cognitive deficits. Tauopathy causes sex-dependent disruptions of OX2 receptor signalling/function, which may have implications for choice of hypnotic therapeutics in tauopathies.

Riboflavin protects against heart failure via SCAD-dependent DJ-1-Keap1-Nrf2 signalling pathway

BACKGROUND AND PURPOSE

Our recent studies have shown that flavin adenine dinucleotide (FAD) exerts cardiovascular protective effects by supplementing short-chain acyl-CoA dehydrogenase (SCAD). The current study aimed to elucidate whether riboflavin (the precursor of FAD) could improve heart failure via activating SCAD and the DJ-1-Keap1-Nrf2 signalling pathway.

EXPERIMENTAL APPROACH

Riboflavin treatment was given to the mouse transverse aortic constriction (TAC)-induced heart failure model. Cardiac structure and function, energy metabolism and apoptosis index were assessed, and relevant signalling proteins were analysed. The mechanisms underlying the cardioprotection by riboflavin were analysed in the cell apoptosis model induced by tert-butyl hydroperoxide (tBHP).

KEY RESULTS

In vivo, riboflavin ameliorated myocardial fibrosis and energy metabolism, improved cardiac dysfunction and inhibited oxidative stress and cardiomyocyte apoptosis in TAC-induced heart failure. In vitro, riboflavin ameliorated cell apoptosis in H9C2 cardiomyocytes by decreasing reactive oxygen species (ROS). At the molecular level, riboflavin significantly restored FAD content, SCAD expression and enzymatic activity, activated DJ-1 and inhibited the Keap1-Nrf2/HO1 signalling pathway in vivo and in vitro. SCAD knockdown exaggerated the tBHP-induced DJ-1 decrease and Keap1-Nrf2/HO1 signalling pathway activation in H9C2 cardiomyocytes. The knockdown of SCAD abolished the anti-apoptotic effects of riboflavin on H9C2 cardiomyocytes. DJ-1 knockdown hindered SCAD overexpression anti-apoptotic effects and regulation on Keap1-Nrf2/HO1 signalling pathway in H9C2 cardiomyocytes.

CONCLUSIONS AND IMPLICATIONS

Riboflavin exerts cardioprotective effects on heart failure by improving oxidative stress and cardiomyocyte apoptosis via FAD to stimulate SCAD and then activates the DJ-1-Keap1-Nrf2 signalling pathway.

Role of circadian clock in the chronoefficacy and chronotoxicity of clopidogrel

BACKGROUND AND PURPOSE

The role of circadian locomotor output cycles kaput (CLOCK) in regulating drug chronoefficacy and chronotoxicity remains elusive. Here, we aimed to uncover the impact of CLOCK and dosing time on clopidogrel efficacy and toxicity.

EXPERIMENTAL APPROACH

The antiplatelet effect, toxicity and pharmacokinetics experiments were conducted with Clock-/- mice and wild-type mice, after gavage administration of clopidogrel at different circadian time points. The expression levels of drug-metabolizing enzymes were determined by quantitative polymerase chain reaction (qPCR) and western blotting. Transcriptional gene regulation was investigated using luciferase reporter and chromatin immunoprecipitation assays.

KEY RESULTS

The antiplatelet effect and toxicity of clopidogrel in wild-type mice showed a dosing time-dependent variation. Clock ablation reduced the antiplatelet effect of clopidogrel, but increased clopidogrel-induced hepatotoxicity, with attenuated rhythms of clopidogrel active metabolite (Clop-AM) and clopidogrel, respectively. We found that Clock regulated the diurnal variation of Clop-AM formation by modulating the rhythmic expression of CYP1A2 and CYP3A1, and altered clopidogrel chronopharmacokinetics by regulation of CES1D expression. Mechanistic studies revealed that CLOCK activated Cyp1a2 and Ces1d transcription by directly binding to the enhancer box (E-box) elements in their promoters, and promoted Cyp3a11 transcription through enhancing the transactivation activity of albumin D-site-binding protein (DBP) and thyrotroph embryonic factor (TEF).

CONCLUSIONS AND IMPLICATIONS

CLOCK regulates the diurnal rhythmicity in clopidogrel efficacy and toxicity through regulation of CYP1A2, CYP3A11 and CES1D expression. These findings may contribute to optimizing dosing schedules for clopidogrel and may deepen understanding of the circadian clock and chronopharmacology.

Anthelmintic nitazoxanide protects against experimental pulmonary fibrosis

BACKGROUND AND PURPOSE

Nitazoxanide is a therapeutic anthelmintic drug. Our previous studies found that nitazoxanide and its metabolite tizoxanide activated adenosine 5'-monophosphate-activated protein kinase (AMPK) and inhibited signal transducer and activator of transcription 3 (STAT3) signals. As AMPK activation and/or STAT3 inhibition are targets for treating pulmonary fibrosis, we hypothesized that nitazoxanide would be effective in experimental pulmonary fibrosis.

EXPERIMENTAL APPROACH

The mitochondrial oxygen consumption rate of cells was measured by using the high-resolution respirometry system Oxygraph-2K. The mitochondrial membrane potential of cells was evaluated by tetramethyl rhodamine methyl ester (TMRM) staining. The target protein levels were measured by using western blotting. The mice pulmonary fibrosis model was established through intratracheal instillation of bleomycin. The examination of the lung tissues changes were carried out using haematoxylin and eosin (H&E), and Masson staining.

KEY RESULTS

Nitazoxanide and tizoxanide activated AMPK and inhibited STAT3 signalling in human lung fibroblast cells (MRC-5 cells). Nitazoxanide and tizoxanide inhibited transforming growth factor-β1 (TGF-β1)-induced proliferation and migration of MRC-5 cells, collagen-I and α-smooth muscle cell actin (α-SMA) expression, and collagen-I secretion from MRC-5 cells. Nitazoxanide and tizoxanide inhibited epithelial-mesenchymal transition (EMT) and inhibited TGF-β1-induced Smad2/3 activation in mouse lung epithelial cells (MLE-12 cells). Oral administration of nitazoxanide reduced the bleomycin-induced mice pulmonary fibrosis and, in the established bleomycin-induced mice, pulmonary fibrosis. Delayed nitazoxanide treatment attenuated the fibrosis progression.

CONCLUSIONS AND IMPLICATIONS

Nitazoxanide improves the bleomycin-induced pulmonary fibrosis in mice, suggesting a potential application of nitazoxanide for pulmonary fibrosis treatment in the clinic.

Sanguinarine induces apoptosis in osteosarcoma by attenuating the binding of STAT3 to the single-stranded DNA-binding protein 1 (SSBP1) promoter region

BACKGROUND AND PURPOSE

Osteosarcoma, a primary malignant bone tumour prevalent among adolescents and young adults, remains a considerable challenge despite protracted progress made in enhancing patient survival rates over the last 40 years. Consequently, the development of novel therapeutic approaches for osteosarcoma is imperative. Sanguinarine (SNG), a compound with demonstrated potent anticancer properties against various malignancies, presents a promising avenue for exploration. Nevertheless, the intricate molecular mechanisms underpinning SNG's actions in osteosarcoma remain elusive, necessitating further elucidation.

EXPERIMENTAL APPROACH

Single-stranded DNA-binding protein 1 (SSBP1) was screened out by differential proteomic analysis. Apoptosis, cell cycle, reactive oxygen species (ROS) and mitochondrial changes were assessed via flow cytometry. Western blotting and quantitative real-time reverse transcription PCR (qRT-PCR) were used to determine protein and gene levels. The antitumour mechanism of SNG was explored at a molecular level using chromatin immunoprecipitation (ChIP) and dual luciferase reporter plasmids.

KEY RESULTS

Our investigation revealed that SNG exerted an up-regulated effect on SSBP1, disrupting mitochondrial function and inducing apoptosis. In-depth analysis uncovered a mechanism whereby SNG hindered the JAK/signal transducer and activator of transcription 3 (STAT3) signalling pathway, relieved the inhibitory effect of STAT3 on SSBP1 transcription, and inhibited the downstream PI3K/Akt/mTOR signalling axis, ultimately activating apoptosis.

CONCLUSIONS AND IMPLICATIONS

The study delved further into elucidating the anticancer mechanism of SNG in osteosarcoma. Notably, we unravelled the previously undisclosed apoptotic potential of SSBP1 in osteosarcoma cells. This finding holds substantial promise in advancing the development of novel anticancer drugs and identification of therapeutic targets.

Regulation of the ATP-binding cassette transporters ABCB1, ABCG2 and ABCC5 by nuclear receptors in porcine blood-brain barrier endothelial cells

BACKGROUND AND PURPOSE

Blood-brain barrier (BBB) ABCB1, ABCG2 and ABCC5 transporters influence central therapeutic drug distribution. Transporter expression is regulated by the NR3C1, NR1I3 and NR1I2 nuclear receptors, but their precise roles in brain are poorly understood. We investigated the effects of selective ligand-based activation of NR3C1, NR1I3, NR1I2 and NR2B1 in porcine brain endothelial cells (PBECs).

EXPERIMENTAL APPROACH

Primary cultures of PBECs were exposed to NR3C1, NR1I3 and NR1I2 ligands and ABCB1, ABCG2 and ABCC5 transporter activities determined by measuring intracellular accumulation of fluorescent probes. Western blotting was used to determine the effects of receptor ligands on expression of ABCB1, ABCG2, ABCC5, NR1I2, NR1I3, NR3C1 and NR2B1. Fluorescent immunocytochemistry was employed to assess the effects of receptor ligands on the cellular localisation of NR1I2 and NR1I3.

KEY RESULTS

The NR1I2 agonist rifampicin significantly up-regulated ABCG2 activity, which is counteracted by co-treatment with NR1I2 antagonist l-sulforaphane. The NR1I3 agonist 6-(4-chlorophenyl)-imidazo[2,1-b]thiazole-5-carbaldehyde and inverse agonist meclizine significantly down-regulated ABCB1, ABCG2 and ABCC5 activity. NR3C1 agonist dexamethasone significantly increased ABCB1, ABCG2 and ABCC5 activity and ABCG2 and ABCC5 protein expression, which was counteracted by co-treatment with the NR3C1 antagonist mifepristone. This first study demonstrates that NR1I3 and NR3C1 regulate ABCC5 activity and protein expression in BBB endothelial cells.

CONCLUSIONS AND IMPLICATIONS

In PBECs, expression of key ATP-binding cassette (ABC) transporters and nuclear receptors is differentially regulated by NR1I3, NR1I2, NR3C1 and NR2B1. This will help to better understand the response of the BBB to physiological and pharmacological activation of nuclear receptors.

Assessment of the potential of novel and classical opioids to induce respiratory depression in mice

BACKGROUND AND PURPOSE

Opioid-induced respiratory depression limits the use of μ-opioid receptor agonists in clinical settings and is the main cause of opioid overdose fatalities. The relative potential of different opioid agonists to induce respiratory depression at doses exceeding those producing analgesia is understudied despite its relevance to assessments of opioid safety. Here we evaluated the respiratory depressant and anti-nociceptive effects of three novel opioids and relate these measurements to their in vitro efficacy.

EXPERIMENTAL APPROACH

Respiration was measured in awake, freely moving male CD-1 mice using whole body plethysmography. Anti-nociception was measured using the hot plate test. Morphine, oliceridine and tianeptine were administered intraperitoneally, whereas methadone, oxycodone and SR-17018 were administered orally. Receptor activation and arrestin-3 recruitment were measured in HEK293 cells using BRET assays.

KEY RESULTS

Across the dose ranges examined, all opioids studied depressed respiration in a dose-dependent manner, with similar effects at the highest doses, and with tianeptine and oliceridine showing reduced duration of effect, when compared with morphine, oxycodone, methadone and SR-17018. When administered at doses that induced similar respiratory depression, all opioids induced similar anti-nociception, with tianeptine and oliceridine again showing reduced duration of effect. These data were consistent with the in vitro agonist activity of the tested compounds.

CONCLUSION AND IMPLICATIONS

In addition to providing effective anti-nociception, the novel opioids, oliceridine, tianeptine and SR-17018 depress respiration in male mice. However, the different potencies and kinetics of effect between these novel opioids may be relevant to their therapeutic application in different clinical settings.

SerpinB1 is required for Rev-erbα-mediated protection against acute lung injury induced by lipopolysaccharide-in mice

BACKGROUND AND PURPOSE

Acute lung injury (ALI) is a serious, life-threatening inflammation of the lungs that still lacks effective treatment. We previously showed that serine protease inhibitor B1 (SerpinB1) protects against ALI induced by orthotopic autologous liver transplantation. However, the role of SerpinB1 in lipopolysaccharide (LPS)-induced ALI and its regulatory mechanisms are not known.

EXPERIMENTAL APPROACH

Wild-type (WT) and SerpinB1 knockout (KO) mice were treated with intratracheal LPS stimulation to induce ALI. Some of the WT and KO mice were injected i.p. with melatonin, a rhythm-related protein Rev-erbα agonist. The circadian rhythm in WT mice was disrupted by exposing mice to 24 h of continuous dark or light conditions after intratracheal LPS. Neutrophils were isolated from alveolar lavage fluid of WT and KO mice, and from human peripheral blood. Neutrophils were treated with LPS and melatonin.

KEY RESULTS

Disruption of circadian rhythm by either 24-h dark or light conditions exacerbated LPS-induced ALI and decreased expression of Rev-erbα and SerpinB1 protein in lung, whereas melatonin treatment increased SerpinB1 expression and attenuated LPS-induced ALI in WT mice, but not in KO mice. In isolated neutrophils, Rev-erbα was co-localized with SerpinB1 and bound to its promoter to trigger SerpinB1 transcription. Furthermore, LPS stimulation increased formation of neutrophil extracellular traps, which was reversed by melatonin treatment in neutrophils from WT mice, but not from KO mice.

CONCLUSION AND IMPLICATIONS

In mice, SerpinB1 is rhythmically regulated by Rev-erbα, and its down-regulation exacerbates LPS-induced ALI by inducing formation of neutrophil extracellular traps.

Subtype-specific modulation of human KV 7 channels by the anticonvulsant cannabidiol through a lipid-exposed pore-domain site

BACKGROUND AND PURPOSE

Cannabidiol (CBD) is used clinically as an anticonvulsant. Its precise mechanism of action has remained unclear. CBD was recently demonstrated to enhance the activity of the neuronal KV 7.2/7.3 channel, which may be one important contributor to CBD anticonvulsant effect. Curiously, CBD inhibits the closely related cardiac KV 7.1/KCNE1 channel. Whether and how CBD affects other KV 7 subtypes remains uninvestigated and the CBD interaction sites mediating these diverse effects remain unknown.

EXPERIMENTAL APPROACH

Here, we used electrophysiology, molecular dynamics simulations, molecular docking and site-directed mutagenesis to address these questions.

KEY RESULTS

We found that CBD modulates the activity of all human KV 7 subtypes and that the effects are subtype dependent. CBD enhanced the activity of KV 7.2-7.5 subtypes, seen as a V50 shift towards more negative voltages or increased maximum conductance. In contrast, CBD inhibited the KV 7.1 and KV 7.1/KCNE1 channels, seen as a V50 shift towards more positive voltages and reduced conductance. In KV 7.2 and KV 7.4, we propose a CBD interaction site at the subunit interface in the pore domain that overlaps with the interaction site of other compounds, notably the anticonvulsant retigabine. However, CBD relies on other residues for its effects than the conserved tryptophan that is critical for retigabine effects. We propose a similar, though not identical CBD site in KV 7.1, with a non-conserved phenylalanine being important.

CONCLUSIONS AND IMPLICATIONS

We identify novel targets of CBD, contributing to a better understanding of CBD clinical effects and provide mechanistic insights into how CBD modulates different KV 7 subtypes.

Gβγ subunit signalling underlies neuropeptide Y-stimulated vasoconstriction in rat mesenteric and coronary arteries

BACKGROUND AND PURPOSE

Raised serum concentrations of the sympathetic co-transmitter neuropeptide Y (NPY) are linked to cardiovascular diseases. However, the signalling mechanism for vascular smooth muscle (VSM) constriction to NPY is poorly understood. Therefore, the present study investigated the mechanisms of NPY-induced vasoconstriction in rat small mesenteric (RMA) and coronary (RCA) arteries.

EXPERIMENTAL APPROACH

Third-order mesenteric or intra-septal arteries from male Wistar rats were assessed in wire myographs for isometric tension, VSM membrane potential and VSM intracellular Ca2+ events.

KEY RESULTS

NPY stimulated concentration-dependent vasoconstriction in both RMA and RCA, which was augmented by blocking NO synthase or endothelial denudation in RMA. NPY-mediated vasoconstriction was blocked by the selective Y1 receptor antagonist BIBO 3304 and Y1 receptor protein expression was detected in both the VSM and endothelial cells in RMA and RCA. The selective Gβγ subunit inhibitor gallein and the PLC inhibitor U-73122 attenuated NPY-induced vasoconstriction. Signalling via the Gβγ-PLC pathway stimulated VSM Ca2+ waves and whole-field synchronised Ca2+ flashes in RMA and increased the frequency of Ca2+ flashes in myogenically active RCA. Furthermore, in RMA, the Gβγ pathway linked NPY to VSM depolarization and generation of action potential-like spikes associated with intense vasoconstriction. This depolarization activated L-type voltage-gated Ca2+ channels, as nifedipine abolished NPY-mediated vasoconstriction.

CONCLUSIONS AND IMPLICATIONS

These data suggest that the Gβγ subunit, which dissociates upon Y1 receptor activation, initiates VSM membrane depolarization and Ca2+ mobilisation to cause vasoconstriction. This model may help explain the development of microvascular vasospasm during raised sympathetic nerve activity.

Sexually dimorphic effects of monoacylglycerol lipase inhibitor MJN110 on stress-related behaviour and drinking in Marchigian Sardinian alcohol-preferring rats

BACKGROUND AND PURPOSE

The endocannabinoid (eCB) system plays an important homeostatic role in the regulation of stress circuits and has emerged as a therapeutic target to treat stress disorders and alcohol use disorder (AUD). Extensive research has elucidated a role for the eCB anandamide (AEA), but less is known about 2-arachidonoylglycerol (2-AG) mediated signalling.

EXPERIMENTAL APPROACH

We pharmacologically enhanced eCB signalling by inhibiting the 2-AG metabolizing enzyme, monoacylglycerol lipase (MAGL), in male and female Marchigian Sardinian alcohol-preferring (msP) rats, a model of innate alcohol preference and stress hypersensitivity, and in control Wistar rats. We tested the acute effect of the selective MAGL inhibitor MJN110 in alleviating symptoms of alcohol drinking, anxiety, irritability and fear.

KEY RESULTS

A single systemic administration of MJN110 increased 2-AG levels in the central amygdala, prelimbic and infralimbic cortex but did not acutely alter alcohol drinking. MAGL inhibition reduced aggressive behaviours in female msPs, and increased defensive behaviours in male msPs, during the irritability test. Moreover, in the novelty-induced hypophagia test, MJN110 selectively enhanced palatable food consumption in females, mitigating stress-induced food suppression. Lastly, msP rats showed increased conditioned fear behaviour compared with Wistar rats, and MJN110 reduced context-associated conditioned fear responses, but not cue-probed fear expression, in male msPs.

CONCLUSIONS AND IMPLICATIONS

Acute inhibition of MAGL attenuated some stress-related responses in msP rats but not voluntary alcohol drinking. Our results provide new insights into the sex dimorphism documented in stress-induced responses. Sex-specific eCB-based approaches should be considered in the clinical development of therapeutics.

Disruption of tonic endocannabinoid signalling triggers cellular, behavioural and neuroendocrine responses consistent with a stress response

BACKGROUND AND PURPOSE

Endocannabinoid (eCB) signalling gates many aspects of the stress response, including the hypothalamic-pituitary-adrenal (HPA) axis. The HPA axis is controlled by corticotropin releasing hormone (CRH) producing neurons in the paraventricular nucleus of the hypothalamus (PVN). Disruption of eCB signalling increases drive to the HPA axis, but the mechanisms subserving this process are poorly understood.

EXPERIMENTAL APPROACH

Using an array of cellular, endocrine and behavioural readouts associated with activation of CRH neurons in the PVN, we evaluated the contributions of tonic eCB signalling to the generation of a stress response.

KEY RESULTS

The CB1 receptor antagonist/inverse agonist AM251, neutral antagonist NESS243 and NAPE PLD inhibitor LEI401 all uniformly increased Fos in the PVN, unmasked stress-linked behaviours, such as grooming, and increased circulating CORT, recapitulating the effects of stress. Similar effects were also seen after direct administration of AM251 into the PVN, while optogenetic inhibition of PVN CRH neurons ameliorated stress-like behavioural changes produced by disruption of eCB signalling.

CONCLUSIONS AND IMPLICATIONS

These data indicate that under resting conditions, constitutive eCB signalling restricts activation of the HPA axis through local regulation of CRH neurons in the PVN.

Pharmacological targeting of Axin2 suppresses cell growth and metastasis in colorectal cancer

BACKGROUND AND PURPOSE

The scaffold molecule Axin2 is constitutively activated in colorectal cancer (CRC) and functions as a potent promoter of CRC behaviour. Pharmacological targeting of Axin2 may therefore exert a therapeutic effect in patients with CRC. Here, we discovered a potent small-molecule inhibitor of Axin2, based on the mechanism by which Axin2 is regulated post-translationally, and investigated its antitumour effects.

EXPERIMENTAL APPROACH

Compound discovery and its inhibitory action on Axin2 protein were revealed by microscale thermophoresis, in vitro kinase assay, quantitative kinetic assay, immunoblotting/immunoprecipitation, RT-qPCR and cycloheximide pulse-chase assay. Compound antitumour effects and the underlying mechanisms were evaluated in multiple cell-based assays and mouse models.

KEY RESULTS

We discovered that glycogen synthase kinase 3β (GSK3β) phosphorylates Axin2 at two consensus motifs and coupled Axin2 phosphorylation to its ubiquitination (mediated by the E3 ligase β-Trcp2) and proteasomal degradation. The binding of Axin2 to GSK3β in CRC cells is faint, which enables most of the Axin2 protein to maintain an unphosphorylated status and thereby permits the cells to preserve high levels of Axin2. Importantly, we identified a small-molecule compound CW85319 that enhances Axin2's interaction with GSK3β via forming a high affinity for Axin2. Treatment of CRC cells with CW85319 enhanced Axin2 binding with GSK3β, thereby promoting Axin2 phosphorylation, subsequent ubiquitination, and degradation. Furthermore, we demonstrated that CW85319 efficiently suppressed Axin2-driven CRC growth and metastasis, without eliciting side toxicity.

CONCLUSIONS AND IMPLICATIONS

These findings suggest that pharmacological targeting of Axin2 by CW85319 may provide therapeutic benefits against certain human cancers, especially CRC.

Use of Saccharomyces boulardii CNCM I-745 as therapeutic strategy for prevention of nonsteroidal anti-inflammatory drug-induced intestinal injury

BACKGROUND AND PURPOSE

Nonsteroidal anti-inflammatory drugs (NSAIDs) can be associated with severe adverse digestive effects. This study examined the protective effects of the probiotic Saccharomyces boulardii CNCM I-745 in a rat model of diclofenac-induced enteropathy.

EXPERIMENTAL APPROACH

Enteropathy was induced in 40-week-old male rats by intragastric diclofenac (4 mg·kg-1 BID for 14 days). S. boulardii CNCM I-745 (3 g·kg-1 BID by oral gavage) was administered starting 14 days before (preventive protocol) or along with (curative protocol) diclofenac administration. Ileal damage, inflammation, barrier integrity, gut microbiota composition and toll-like receptors (TLRs)-nuclear factor κB (NF-κB) pathway were evaluated.

KEY RESULTS

Diclofenac elicited intestinal damage, along with increments of myeloperoxidase, malondialdehyde, tumour necrosis factor and interleukin-1β, overexpression of TLR2/4, myeloid differentiation primary response 88 (Myd88) and NF-κB p65, increased faecal calprotectin and butyrate levels, and decreased blood haemoglobin levels, occludin and butyrate transporter monocarboxylate transporter 1 (MCT1) expression. In addition, diclofenac provoked a shift of bacterial taxa in both faecal and ileal samples. Treatment with S. boulardii CNCM I-745, in both preventive and curative protocols, counteracted the majority of these deleterious changes. Only preventive administration of the probiotic counteracted NSAID-induced decreased expression of MCT1 and increase in faecal butyrate levels. Occludin expression, after probiotic treatment, did not significantly change.

CONCLUSIONS AND IMPLICATIONS

Treatment with S. boulardii CNCM I-745 prevents diclofenac-induced enteropathy through anti-inflammatory and antioxidant activities. Such effects are likely to be related to increased tissue butyrate bioavailability, through an improvement of butyrate uptake by the enteric mucosa.

A novel small molecule inhibitor of p38⍺ MAP kinase augments cardiomyocyte cell cycle entry in response to direct cell cycle stimulation

BACKGROUND AND PURPOSE

Myocardial infarction (MI) is the leading cause of mortality globally due in part to the limited ability of cardiomyocytes (CMs) to regenerate. Recently, we demonstrated that overexpression of four-cell cycle factors, CDK1, CDK4, cyclin B1 and cyclin D1 (4F), induced cell division in ~20% of the post-mitotic CMs overexpressed 4F. The current study aims to identify a small molecule that augments 4F-induced CM cycle induction.

EXPERIMENTAL APPROACH, KEY RESULTS

Screening of small molecules with a potential to augment 4F-induced cell-cycle induction in 60-day-old mature human induced pluripotent cardiomyocytes (hiPS-CMs) revealed N-(4,6-Dimethylpyridin-2-yl)-4-(pyridine-4-yl)piperazine-1-carbothioamide (NDPPC), which activates cell cycle progression in 4F-transduced hiPS-CMs. Autodock tool and Autodock vina computational methods showed that NDPPC has a potential interaction with the binding site at the human p38⍺ mitogen-activated protein kinase (p38⍺ MAP kinase), a critical negative regulator of the mammalian cell cycle. A p38 MAP kinase activity assay showed that NDPPC inhibits p38⍺ with 5-10 times lower IC50 compared to the other P38 isoforms in a dose-dependent manner. Overexpression of p38⍺ MAP kinase in CMs inhibited 4F cell cycle induction, and treatment with NDPPC reversed the cell cycle inhibitory effect.

CONCLUSION AND IMPLICATIONS

NDPPC is a novel inhibitor for p38 MAP kinase and is a promising drug to augment CM cell cycle response to the 4F. NDPPC could become an adjunct treatment with other cell cycle activators for heart failure treatment.

Inhibition of Brd4 alleviates osteoarthritis pain via suppression of neuroinflammation and activation of Nrf2-mediated antioxidant signalling

BACKGROUND AND PURPOSE

Osteoarthritis (OA) pain remains a major clinical problem. It is urgent to identify novel therapeutic approaches for OA pain states. Bromodomain and extra-terminal (BET) protein inhibitors have robust anti-inflammatory effects in several pain models. However, the underlying mechanisms of these inhibitors in OA pain have not been determined. We, therefore, investigated the effects and the underlying mechanism(s) of BET inhibition on pain-related behaviours in a rat model of OA.

EXPERIMENTAL APPROACH

The OA model was established by intra-articular injection of monosodium iodoacetate (MIA) in rat knees. Pain behaviours were assessed in rats by hindlimb weight-bearing asymmetry, mechanical allodynia and thermal hyperalgesia. Possible mechanisms underlying BET inhibition were explored in the MIA-induced OA pain model in the spinal cord and dorsal root ganglia (DRG).

KEY RESULTS

Inhibiting bromodomain-containing protein 4 (Brd4) with either JQ1 or MS417, or using AAV2/9-shRNA-Brd4-EGFP-mediated knockdown of Brd4 genes, significantly attenuated MIA-induced pain behaviours. Brd4 inhibition suppressed NF-κB and NF-κB-mediated inflammatory cytokines in both the spinal cord and DRG in rats with MIA-induced OA pain. Brd4 inhibition also attenuated the oxidative stress and promoted nuclear factor erythroid-2-related factor 2 (Nrf2)-dependent antioxidant genes in both the spinal cord and DRG in our odel of MIA-induced OA pain.

CONCLUSIONS AND IMPLICATIONS

In conclusion, Brd4 inhibition alleviated MIA-induced OA pain in rats, via suppression of neuroinflammation and activation of Nrf2-mediated antioxidant signalling. Although our model does not perfectly represent how OA develops in humans, inhibition of Brd4 may provide novel insights into possible treatments for OA pain.

The small molecule fibroblast growth factor receptor inhibitor infigratinib exerts anti-inflammatory effects and remyelination in a model of multiple sclerosis

BACKGROUND AND PURPOSE

Fibroblast growth factors and receptors (FGFR) have been shown to modulate inflammation and neurodegeneration in multiple sclerosis (MS). The selective FGFR inhibitor infigratinib has been shown to be effective in cancer models. Here, we investigate the effects of infigratinib on prevention and suppression of first clinical episodes of myelin oligodendrocyte glycoprotein (MOG)35-55 -induced experimental autoimmune encephalomyelitis (EAE) in mice.

EXPERIMENTAL APPROACH

The FGFR inhibitor infigratinib was given over 10 days from the time of experimental autoimmune encephalomyelitis induction or the onset of symptoms. The effects of infigratinib on proliferation, cytotoxicity and FGFR signalling proteins were studied in lymphocyte cell lines and microglial cells.

KEY RESULTS

Administration of infigratinib prevented by 40% and inhibited by 65% first clinical episodes of the induced experimental autoimmune encephalomyelitis. In the spinal cord, infiltration of lymphocytes and macrophages/microglia, destruction of myelin and axons were reduced by infigratinib. Infigratinib enhanced the maturation of oligodendrocytes and increased remyelination. In addition, infigratinib resulted in an increase of myelin proteins and a decrease in remyelination inhibitors. Further, lipids associated with neurodegeneration such as lysophosphatidylcholine and ceramide were decreased as were proliferation of T cells and microglial cells.

CONCLUSION AND IMPLICATIONS

This proof of concept study demonstrates the therapeutic potential of targeting FGFRs in a disease model of multiple sclerosis. Application of oral infigratinib resulted in anti-inflammatory and remyelinating effects. Thus, infigratinib may have the potential to slow disease progression or even to improve the disabling symptoms of multiple sclerosis.

Anti-cathepsin D immunotherapy triggers both innate and adaptive anti-tumour immunity in breast cancer

BACKGROUND AND PURPOSE

Triple-negative breast cancer (TNBC) has poorer outcomes than other breast cancers (BC), including HER2+ BC. Cathepsin D (CathD) is a poor prognosis marker overproduced by BC cells, hypersecreted in the tumour microenvironment with tumour-promoting activity. Here, we characterized the immunomodulatory activity of the anti-CathD antibody F1 and its improved Fab-aglycosylated version (F1M1) in immunocompetent mouse models of TNBC (C57BL/6 mice harbouring E0771 cell grafts) and HER2-amplified BC (BALB/c mice harbouring TUBO cell grafts).

EXPERIMENTAL APPROACH

CathD expression was evaluated by western blotting and immunofluorescence, and antibody binding to CathD by ELISA. Antibody anti-tumour efficacy was investigated in mouse models. Immune cell recruitment and activation were assessed by immunohistochemistry, immunophenotyping, and RT-qPCR.

KEY RESULTS

F1 and F1M1 antibodies remodelled the tumour immune landscape. Both antibodies promoted innate antitumour immunity by preventing the recruitment of immunosuppressive M2-polarized tumour-associated macrophages (TAMs) and by activating natural killer cells in the tumour microenvironment of both models. This translated into a reduction of T-cell exhaustion markers in the tumour microenvironment that could be locally supported by enhanced activation of anti-tumour antigen-presenting cell (M1-polarized TAMs and cDC1 cells) functions. Both antibodies inhibited tumour growth in the highly-immunogenic E0771 model, but only marginally in the immune-excluded TUBO model, indicating that anti-CathD immunotherapy is more relevant for BC with a high immune cell infiltrate, as often observed in TNBC.

CONCLUSION AND IMPLICATION

Anti-CathD antibody-based therapy triggers the anti-tumour innate and adaptive immunity in preclinical models of BC and is a promising immunotherapy for immunogenic TNBC.

Cognitive dysfunction and impaired neuroplasticity following repeated exposure to the synthetic cannabinoid JWH-018 in male mice

BACKGROUND AND PURPOSE

Psychotic disorders have been reported in long-term users of synthetic cannabinoids. This study aims at investigating the long-lasting effects of repeated JWH-018 exposure.

EXPERIMENTAL APPROACH

Male CD-1 mice were injected with vehicle, JWH-018 (6 mg·kg-1 ), the CB1 -antagonist NESS-0327 (1 mg·kg-1 ) or co-administration of NESS-0327 and JWH-018, every day for 7 days. After 15 or 16 days washout, we investigated the effects of JWH-018 on motor function, memory, social dominance and prepulse inhibition (PPI). We also evaluated glutamate levels in dialysates from dorsal striatum, striatal dopamine content and striatal/hippocampal neuroplasticity focusing on the NMDA receptor complex and the neurotrophin BDNF. These measurements were accompanied by in vitro electrophysiological evaluations in hippocampal preparations. Finally, we investigated the density of CB1 receptors and levels of the endocannabinoid anandamide (AEA) and 2-arachidonoylglycerol (2-AG) and their main synthetic and degrading enzymes in the striatum and hippocampus.

KEY RESULTS

The repeated treatment with JWH-018 induced psychomotor agitation while reducing social dominance, recognition memory and PPI in mice. JWH-018 disrupted hippocampal LTP and decreased BDNF expression, reduced the synaptic levels of NMDA receptor subunits and decreased the expression of PSD95. Repeated exposure to JWH-018, reduced hippocampal CB1 receptor density and induced a long-term alteration in AEA and 2-AG levels and their degrading enzymes, FAAH and MAGL, in the striatum.

CONCLUSION AND IMPLICATIONS

Our findings suggest that repeated administration of a high dose of JWH-018 leads to the manifestation of psychotic-like symptoms accompanied by alterations in neuroplasticity and change in the endocannabinoid system.

Conserved transcriptional programming across sex and species after peripheral nerve injury predicts treatments for neuropathic pain

BACKGROUND AND PURPOSE

Chronic pain is a devastating problem affecting one in five individuals around the globe, with neuropathic pain the most debilitating and poorly treated type of chronic pain. Advances in transcriptomics have contributed to cataloguing diverse cellular pathways and transcriptomic alterations in response to peripheral nerve injury but have focused on phenomenology and classifying transcriptomic responses.

EXPERIMENTAL APPROACH

To identifying new types of pain-relieving agents, we compared transcriptional reprogramming changes in the dorsal spinal cord after peripheral nerve injury cross-sex and cross-species, and imputed commonalities, as well as differences in cellular pathways and gene regulation.

KEY RESULTS

We identified 93 transcripts in the dorsal horn that were increased by peripheral nerve injury in male and female mice and rats. Following gene ontology and transcription factor analyses, we constructed a pain interactome for the proteins encoded by the differentially expressed genes, discovering new, conserved signalling nodes. We investigated the interactome with the Drug-Gene database to predict FDA-approved medications that may modulate key nodes within the network. The top hit from the analysis was fostamatinib, the molecular target of which is the non-receptor spleen associated tyrosine kinase (Syk), which our analysis had identified as a key node in the interactome. We found that intrathecally administrating the active metabolite of fostamatinib, R406 and another Syk inhibitor P505-15, significantly reversed pain hypersensitivity in both sexes.

CONCLUSIONS AND IMPLICATIONS

Thus, we have identified and shown the efficacy of an agent that could not have been previously predicted to have analgesic properties.