ARRIVE 2.0 and the British Journal of Pharmacology: Updated guidance for 2020

Disruption of survivin protein expression by treatment with YM155 accelerates the resolution of neutrophilic inflammation

BACKGROUND AND PURPOSE

Prolonged survival of neutrophils is essential for determining the progression and severity of inflammatory and immune-mediated disorders, including gouty arthritis. Survivin, an anti-apoptotic molecule, has been described as a regulator of cell survival. This study aims to examine the effects of YM155 treatment, a survivin selective suppressant, in maintaining neutrophil survival in vitro and in vivo experimental settings of neutrophilic inflammation.

EXPERIMENTAL APPROACH

BALB/c mice were injected with monosodium urate (MSU) crystals and treated with YM155 (intra-articularly) at the peak of inflammatory response. Leukocyte recruitment, apoptosis neutrophil and efferocytosis were determined by knee joint wash cell morphology counting and flow cytometry. Resolution interval (Ri) was quantified by neutrophil infiltration, monitoring the amplitude and duration of the inflammation. Cytokine production was measured by ELISA. Mechanical hypernociception was assessed using an electronic von Frey aesthesiometer. Efferocytosis was evaluated in zymosan-induced neutrophilic peritonitis. Survivin and cleaved caspase-3 expression was determined in human neutrophils by flow cytometry.

KEY RESULTS

Survivin was expressed in neutrophils during MSU-induced gout, and the treatment with YM155 reduced survivin expression and shortened Ri from ∼8 h observed in vehicle-treated mice to ∼5.5 h, effect accompanied by increased neutrophil apoptosis and efferocytosis, both crucial for the inflammation resolution. Reduced IL-1β and CXCL1 levels were also observed in periarticular tissue. YM155 reduced histopathological score and hypernociceptive response. In human neutrophils, lipopolysaccharide (LPS) increased survivin expression, whereas survivin inhibition with YM155 induced neutrophil apoptosis, with activation of caspase-3.

CONCLUSIONS AND IMPLICATIONS

Survivin may be a promising therapeutic target to control neutrophilic inflammation.

Preclinical development of a standardized extract of Ilex paraguariensis A.St.-Hil for the treatment of obesity and metabolic syndrome

Obesity is a global epidemic often associated with serious medical complications such as diabetes, hypertension and metabolic dysfunction-associated steatohepatitis. Considering the multifactorial nature of these diseases, medicinal plants could be a valuable therapeutic strategy as their phytoconstituents interact with multiple and relevant biological targets. In this context, Ilex paraguariensis emerges as a potential alternative to treat obesity and associated metabolic diseases since several studies have demonstrated its anti-inflammatory, anti-obesity and anti-diabetic effects. We present a comprehensive and complete non-clinical investigation of the efficacy, safety and putative mechanisms of action of a standardized aqueous extract of I. paraguariensis (TI-076). We also describe a scalable preparation of TI-076 and demonstrate its long-term stability. TI-076 exhibits long-term stability and its major constituents are well absorbed orally in mice and rats. The five in vivo proofs of concept studies revealed that TI-076 reduced obesity, hyperglycaemia, blood pressure, liver fat accumulation, levels of serum insulin, leptin and cholesterol, food intake, inflammation and increased GLP-1 levels. The mechanisms through which TI-076 acts seem to involve the modulation of several genes associated with inflammation (Il1b, Nlrp3, Pparα and Pparγ), white adipose and liver metabolism (Cartpt, Mgll, Ramp3, Faah, Cck, Clps, Pparα and Pparγ), liver damage and fibrosis (Creb1, Col1a1 and Col3a1). Finally, TI-076 did not interact with CYP3A4 in vivo and proved to be safe. These findings strongly suggest that TI-076 holds great potential for clinical trials aimed at developing a safe phytomedicine for treating obesity and related metabolic diseases.

A synthetic peptide, derived from neurotoxin GsMTx4, acts as a non-opioid analgesic to alleviate mechanical and neuropathic pain through the TRPV4 channel

Mechanical pain is one of the most common causes of clinical pain, but there remains a lack of effective treatment for debilitating mechanical and chronic forms of neuropathic pain. Recently, neurotoxin GsMTx4, a selective mechanosensitive (MS) channel inhibitor, has been found to be effective, while the underlying mechanism remains elusive. Here, with multiple rodent pain models, we demonstrated that a GsMTx4-based 17-residue peptide, which we call P10581, was able to reduce mechanical hyperalgesia and neuropathic pain. The analgesic effects of P10581 can be as strong as morphine but is not toxic in animal models. The anti-hyperalgesic effect of the peptide was resistant to naloxone (an μ-opioid receptor antagonist) and showed no side effects of morphine, including tolerance, motor impairment, and conditioned place preference. Pharmacological inhibition of TRPV4 by P10581 in a heterogeneous expression system, combined with the use of Trpv4 knockout mice indicates that TRPV4 channels may act as the potential target for the analgesic effect of P10581. Our study identified a potential drug for curing mechanical pain and exposed its mechanism.

Anti-b diminishes hyperlipidaemia and hepatic steatosis in hamsters and mice by suppressing the mTOR/PPARγ and mTOR/SREBP1 signalling pathways

BACKGROUND AND PURPOSE

As a chronic metabolic syndrome, hyperlipidaemia is manifested as aberrantly elevated cholesterol and triglyceride (TG) levels, primarily attributed to disorders in lipid metabolism. Despite the promising outlook for hyperlipidaemia treatment, the need persists for the development of lipid-lowering agents with heightened efficiency and minimal toxicity. This investigation aims to elucidate the lipid-lowering effects and potential pharmacodynamic mechanisms of Anti-b, a novel low MW compound.

EXPERIMENTAL APPROACH

We employed high-fat diet (HFD) in hamsters and mice or oleic acid (OA) in cultures of HepG2 cells and LO2 cells to induce hyperlipidaemia models. We administered Anti-b to assess its therapeutic effects on dyslipidaemia and hepatic steatosis. We used western blotting, RNA sequencing, GO and KEGG analysis, oil red O staining, along with molecular docking and molecular dynamics simulation to elucidate the mechanisms underlying the effects of Anti-b.

KEY RESULTS

Anti-b exhibited a substantial reduction in HFD-induced elevation of blood lipids, liver weight to body weight ratio, liver diameter and hepatic fat accumulation. Moreover, Anti-b demonstrated therapeutic effects in alleviating total cholesterol (TC), TG levels, and lipid accumulation derived from OA in HepG2 cells and LO2 cells. Mechanistically, Anti-b selectively bound to the mTOR kinase protein and increased mTOR thermal stability, resulting in downregulation of phosphorylation level. Notably, Anti-b exerted anti-hyperlipidaemia effects by modulating PPARγ and SREBP1 signalling pathways and reducing the expression level of mSREBP1 and PPARγ proteins.

CONCLUSION AND IMPLICATIONS

In conclusion, our study has provided initial data of a novel low MW compound, Anti-b, designed and synthesised to target mTOR protein directly. Our results indicate that Anti-b may represent a novel class of drugs for the treatment of hyperlipidemia and hepatic steatosis.

NaHS alters synaptic plasticity proteins and enhances dendritic arborization to improve cognitive and motor deficits after traumatic brain injury in mice

BACKGROUND AND PURPOSE

Traumatic brain injury (TBI) is a complex medical condition affecting people globally. Hydrogen sulfide (H2S) is a recently discovered gaseous mediator and is dysregulated in the brain after TBI. Sodium hydrogen sulfide (NaHS), a known donor of H2S, is beneficial in various biological processes involving aging and diseases, including injury. It is neuroprotective against oxidative stress, neuroinflammation, and other secondary injury processes. However, the NaHS-H2S system has not been investigated as a regulator of injury-mediated synaptic plasticity proteins and the underlying mechanisms after TBI.

EXPERIMENTAL APPROACH

We developed a model of TBI in Swiss albino mice to study the effects of exogenous H2S, administered as NaHS. We assessed cognitive function (Barnes maze and novel object recognition) and motor function (rotarod). Brain tissue was analysed with ELISA, qRT-PCR, immunoblotting, Golgi-cox staining, and immunofluorescence.

KEY RESULTS

NaHS administration restored the injury-caused decline in H2S levels. Injury-mediated oxidative stress parameters were improved following NaHS. It down-regulated TBI biomarkers, ameliorated the synaptic marker proteins, and improved cognitive and motor deficits. These changes were accompanied by enhanced dendritic arborization and spine number. Restoration of N-methyl D-aspartate receptor subunits and diminished glutamate and calcium levels, along with marked changes in microtubule-associated protein 2 A and calcium/calmodulin-dependent protein kinase II, formed the basis of the underlying mechanism(s).

CONCLUSION AND IMPLICATIONS

Our findings suggest that NaHS could have therapeutic activity against TBI, as it ameliorated cognitive and motor deficits caused by changes in synaptic plasticity proteins and dendritic arborisation, in our model.

TRPV4 stimulates colonic afferents through mucosal release of ATP and glutamate

BACKGROUND AND PURPOSE

Abdominal pain is a leading cause of morbidity for people living with gastrointestinal disease. Whereas the transient receptor potential vanilloid 4 (TRPV4) ion channel has been implicated in the pathogenesis of abdominal pain, the relative paucity of TRPV4 expression in colon-projecting sensory neurons suggests that non-neuronal cells may contribute to TRPV4-mediated nociceptor stimulation.

EXPERIMENTAL APPROACH

Changes in murine colonic afferent activity were examined using ex vivo electrophysiology in tissues with the gut mucosa present or removed. ATP and glutamate release were measured by bioluminescence assays from human colon organoid cultures and mouse colon. Dorsal root ganglion sensory neuron activity was evaluated by Ca2+ imaging when cultured alone or co-cultured with colonic mucosa.

KEY RESULTS

Bath application of TRPV4 agonist GSK1016790A elicited a robust increase in murine colonic afferent activity, which was abolished by removing the gut mucosa. GSK1016790A promoted ATP and glutamate release from human colon organoid cultures and mouse colon. Inhibition of ATP degradation in mouse colon enhanced the afferent response to GSK1016790A. Pretreatment with purinoceptor or glutamate receptor antagonists attenuated and abolished the response to GSK1016790A when given alone or in combination, respectively. Sensory neurons co-cultured with colonic mucosal cells produced a marked increase in intracellular Ca2+ to GSK1016790A compared with neurons cultured alone.

CONCLUSION AND IMPLICATIONS

Our data indicate that mucosal release of ATP and glutamate is responsible for the stimulation of colonic afferents following TRPV4 activation. These findings highlight an opportunity to target the gut mucosa for the development of new visceral analgesics.

QM107, a novel CD148 (RTP Type J) activating peptide therapy for treating neovascular age-related macular degeneration

BACKGROUND AND PURPOSE

Angiogenesis is a pathological component of neovascular age-related macular degeneration. Current therapies, although successful, are prone to high levels of patient non-response and a loss of efficacy over time, indicating the need to explore other therapeutic avenues. We have shown that an interaction between syndecan-2 and the tyrosine phosphatase receptor CD148 (RTP Type J) results in the ablation of angiogenesis. Here we exploit this pathway to develop a peptide activator of CD148 as a therapy for neovascular age-related macular degeneration.

EXPERIMENTAL APPROACH

We tested a peptide (QM107) derived from syndecan-2 in a variety of angiogenesis models and a pre-clinical model of neovascular age-related macular degeneration. We assessed the toxicological and inflammatory profiles of QM107 and its stability in vitreous humour.

KEY RESULTS

QM107 inhibits angiogenesis in ex vivo sprouting assays and disrupts endothelial microcapillary formation via inhibition of cell migration. QM107 acts through CD148, leading to changes in GSK3A phosphorylation and β1 integrin activation. QM107 elicits a negligible inflammatory response and exhibits limited toxicity in cultured cells, and is stable in vitreous humour. Finally, we show proof of concept that QM107 blocks angiogenesis in vivo using a model of neovascular age-related macular degeneration.

CONCLUSION AND IMPLICATIONS

We have developed a CD148 activating peptide which shows promise in inhibiting angiogenesis in models of neovascular age-related macular degeneration. This treatment could either represent an alternative or augment existing therapies, and owing to its distinct mode of action be used in patients who do not respond to existing treatments.

The expression of contextual fear conditioning involves the dorsal hippocampus TRPV1 receptor interacting with the NMDA/NO/cGMP signalling pathway

BACKGROUND AND PURPOSE

The dorsal hippocampus (dHIP) is pivotal for learning, memory, and defensive responses. Transient receptor potential vanilloid type 1 (TRPV1) receptors in the dHIP modulate contextual fear conditioning by triggering a cascade involving glutamate release, nitric oxide (NO) formation and cyclic guanosine monophosphate (cGMP) production. The present study investigated the involvement of dHIP TRPV1 receptors and their interaction with the glutamate/NO/cGMP signalling pathway in modulating the expression of contextual fear conditioning (CFC).

EXPERIMENTAL APPROACH

Male Wistar rats were submitted to an aversive contextual conditioning session and, 48 h later, were re-introduced to the same aversive environment where the freezing response and autonomic activity (evidenced by increased arterial pressure and heart rate and a decrease in tail temperature) were measured.

KEY RESULTS

The results demonstrated that the TRPV1 antagonist 6-I-CPS in dHIP reduced the expression of CFC, whereas the agonist capsaicin had the opposite effect. Furthermore, dHIP pre-treatment with an NMDA receptor antagonist (AP7), neuronal NO synthase inhibitor (N-propyl-L-arginine), NO scavenger (c-PTIO) or guanylate cyclase inhibitor (ODQ) attenuated capsaicin-induced increases in CFC. Finally, we observed that re-exposure to the aversive chamber increased dHIP NO levels in conditioned animals compared with a non-conditioned group, which was prevented by the administration of the TRPV1 antagonist, 6-I-CPS.

CONCLUSION AND IMPLICATIONS

Our study revealed that TRPV1 receptors in the dHIP play a crucial role in modulating contextual fear expression by acting through the NMDA receptor/NO/cGMP signalling pathway, providing important insights into the underlying mechanisms and potential therapeutic avenues associated with these pathways.

Beneficial effects of CHF6467, a modified human nerve growth factor, in experimental neonatal hypoxic-ischaemic encephalopathy

BACKGROUND AND PURPOSE

Therapeutic hypothermia (TH) has become the standard care to reduce morbidity and mortality in neonates affected by moderate-to-severe hypoxic-ischaemic encephalopathy (HIE). Despite the use of TH for HIE, the incidence of mortality and disabilities remains high.

EXPERIMENTAL APPROACH

Nerve growth factor (NGF) is a potent neurotrophin, but clinical use is limited by its pain eliciting effects. CHF6467 is a recombinant modified form of human NGF devoid of algogenic activity (painless NGF).

KEY RESULTS

In rodent hippocampal slices exposed to oxygen and glucose deprivation, CHF6467 protected neurons from death and reverted neurotransmission impairment when combined with hypothermia. In a model of rat neonatal HIE, intranasal CHF6467 (20 μg kg-1) significantly reduced brain infarct volume versus vehicle when delivered 10 min or 3 h after the insult. CHF6467 (20 and 40 μg kg-1, i.n.), significantly decreased brain infarct volume to a similar extent to TH and when combined, showed a synergistic neuroprotective effect. CHF6467 (20 μg kg-1, i.n.) per se and in combination with hypothermia reversed locomotor coordination impairment (Rotarod test) and memory deficits (Y-maze and novel object recognition test) in the neonatal HIE rat model. Intranasal administration of CHF6467 resulted in meaningful concentrations in the brain, blunted HIE-induced mRNA elevation of brain neuroinflammatory markers and, when combined to TH, significantly counteracted the increase in plasma levels of neurofilament light chain, a peripheral marker of neuroaxonal damage.

CONCLUSION AND IMPLICATIONS

CHF6467 administered intranasally is a promising therapy, in combination with TH, for the treatment of HIE.

tiRNA-Gly-GCC-002 promotes epithelial-mesenchymal transition and fibrosis in lupus nephritis via FKBP5-mediated activation of Smad

BACKGROUND AND PURPOSE

Renal interstitial fibrosis is a frequent pathological manifestation of lupus nephritis (LN). tRNA halves (tiRNAs) are acquired from tRNA-derived small non-coding RNAs (sncRNAs) and are associated with fibrosis. Our previous study indicated enhanced tiRNA-Gly-GCC-002 (tiRNA002) levels in kidneys were positively related to LN-related fibrosis. However, the precise molecular mechanism remains unclear.

EXPERIMENTAL APPROACH

The mimic and agomiR of tiRNA002 were introduced into tubular epithelial cells (TECs) and MRL/lpr mice by transfection. The levels of gene and protein expressions were quantified using real-time quantitative polymerase chain reaction (RT-qPCR), Western blot and immunofluorescence assays.

KEY RESULTS

In TECs treated with LN serum, as well as in the kidneys of MRL/lpr mice, high levels of tiRNA002 directly influenced the epithelial-mesenchymal transition (EMT) and extracellular matrix (ECM) deposition. Furthermore, tiRNA002 overexpression promoted EMT in TECs and accelerated renal interstitial fibrosis in MRL/lpr mice via Smad signalling. The target gene of tiRNA002, FKBP prolyl isomerase 5 (FKBP5), improved Smad signalling by interacting with phosphorylated Smad2/3. Silencing FKBP5 alleviated LN serum- or tiRNA002-mimic-induced EMT in TECs. In addition, FKBP5 overexpression reversed the tiRNA002 knockdown-mediated reduction of EMT and ECM accumulation.

CONCLUSIONS AND IMPLICATIONS

These findings indicated that tiRNA002 is markedly increased in LN, which facilitates renal fibrosis by promoting EMT via FKBP5-mediated Smad signalling. Therefore, targeting tiRNA002 may be an innovative approach to treat renal interstitial fibrosis in LN.

Salvianolic acid B improves the microcirculation in a mouse model of sepsis through a mechanism involving the platelet receptor CD226

BACKGROUND AND PURPOSE

Salvianolic acid B (SalB) demonstrates diverse clinical applications, particularly in cardiovascular and cerebral protection. This study primarily investigated the effects of SalB on sepsis.

EXPERIMENTAL APPROACH

The model of sepsis via caecal ligation puncture (CLP) was established in male C57BL/6 mice. Therapeutic effects of SalB on hepatic and pulmonary injury, inflammatory responses and microcirculatory disturbances in sepsis were evaluated. Platelet aggregation and adhesion were measured via flow cytometry and an adhesion test. After overexpression of platelet-related activating molecules by 293T cells, the efficient binding of SalB and platelet CD226 molecules was further evaluated. Finally, neutralizing antibody experiments were used to assess the mechanism of SalB in alleviating the progression of sepsis.

KEY RESULTS

SalB mitigated hepatic and pulmonary impairments, reduced inflammatory cytokine levels and enhanced mesenteric microvascular blood flow in septic mice. SalB enhanced CLP-induced reduction of platelet count and platelet pressure cumulative volume. SalB reduced platelet adhesion to endothelial cells and platelet aggregation to leukocytes. A high binding efficiency was observed between SalB and the platelet adhesion molecule CD226. Ex vivo, interactions between SalB and platelets from CD226-knockout mice were markedly decreased. In vivo administration of CD226 neutralizing antibodies significantly delayed disease progression and enhanced mesenteric microcirculation in septic mice.

CONCLUSION AND IMPLICATIONS

In our murine model of sepsis, treatment with SalB improved the microcirculatory disturbance and hindered the progression of sepsis by inhibiting platelet CD226 function. Our results suggest SalB is a promising therapeutic approach to the treatment of sepsis.

A pH-sensitive opioid does not exhibit analgesic tolerance in a mouse model of colonic inflammation

BACKGROUND AND PURPOSE

Tolerance to the analgesic effects of opioids and resultant dose escalation is associated with worsening of side effects and greater addiction risk. Here, we compare the development of tolerance to the conventional opioid fentanyl with a novel pH-sensitive μ-opioid receptor (MOR) agonist, (±)-N-(3-fluoro-1-phenethylpiperidine-4-yl)-N-phenyl propionamide (NFEPP) that is active only in acidic inflammatory microenvironments.

EXPERIMENTAL APPROACH

An opioid tolerance model was developed in male C57BL/6 mice, with and without dextran sulphate sodium colitis, using increasing doses of either fentanyl or NFEPP over 5 days. Visceral nociception was assessed in vivo by measuring visceromotor responses (VMRs) to noxious colorectal distensions and in vitro measuring colonic afferent nerve activity of mesenteric nerves and performing patch-clamp recordings from isolated dorsal root ganglia neurons. Somatic thermal nociception was tested using a tail immersion assay. Cardiorespiratory effects were analysed by pulse oximeter experiments.

KEY RESULTS

VMRs and tail immersion tests demonstrated tolerance to fentanyl, but not to NFEPP in colitis mice. Cross-tolerance also occurred to fentanyl, but not to NFEPP. The MOR agonist DAMGO inhibited colonic afferent nerve activity in colitis mice exposed to chronic NFEPP, but not those from fentanyl-treated mice. Similarly, in patch-clamp recordings from isolated dorsal root ganglia neurons, DAMGO inhibited neurons from NFEPP-, but not fentanyl-treated mice.

CONCLUSION AND IMPLICATIONS

NFEPP did not exhibit tolerance in an inflammatory pain model, unlike fentanyl. Consequently, dose escalation to maintain analgesia during an evolving inflammation could be avoided, mitigating the potential risk of side effects.

Excitation-contraction coupling inhibitors potentiate the actions of botulinum neurotoxin type A at the neuromuscular junction

BACKGROUND AND PURPOSE

Botulinum neurotoxin type A1 (BoNT/A) is one of the most potent neurotoxins known. At the same time, it is also one of the safest therapeutic agents used for the treatment of several human disorders and in aesthetic medicine. Notwithstanding great effectiveness, strategies to accelerate the onset and prolong BoNT/A action would significantly ameliorate its pharmacological effects with beneficial outcomes for clinical use.

EXPERIMENTAL APPROACH

Here, we combined BoNT/A with two fast-acting inhibitors of excitation-contraction coupling inhibitors (ECCI), either the μ-conotoxin CnIIIC or dantrolene, and tested the effect of their co-injection on a model of hind-limb paralysis in rodents using behavioural, biochemical, imaging and electrophysiological assays.

KEY RESULTS

The BoNT/A-ECCI combinations accelerated the onset of muscle relaxation. Surprisingly, they also potentiated the peak effect and extended the duration of the three BoNT/A commercial preparations OnabotulinumtoxinA, AbobotulinumtoxinA and IncobotulinumtoxinA. ECCI co-injection increased the number of BoNT/A molecules entering motoneuron terminals, which induced a faster and greater cleavage of SNAP-25 during the onset and peak phases, and prolonged the attenuation of nerve-muscle neurotransmission during the recovery phase. We estimate that ECCI co-injection yields a threefold potentiation in BoNT/A pharmacological activity.

CONCLUSIONS AND IMPLICATIONS

Overall, our results show that the pharmacological activity of BoNT/A can be combined and synergized with other bioactive molecules and uncover a novel strategy to enhance the neuromuscular effects of BoNT/A without altering the neurotoxin moiety or intrinsic activity, thus maintaining its exceptional safety profile.

Dual effects of DLG5 (disks large homolog 5 gene) modulation on chemotherapy-induced thrombocytopenia and nausea/vomiting via the hippo signalling pathway

BACKGROUND AND PURPOSE

The CAPEOX (combination of oxaliplatin and capecitabine) chemotherapy protocol is widely used for colorectal cancer treatment, but it can lead to chemotherapy-induced adverse effects (CRAEs).

EXPERIMENTAL APPROACH

To uncover the mechanisms and potential biomarkers for CRAE susceptibility, we performed whole-genome sequencing on normal colorectal tissue (CRT) before adjuvant chemotherapy. This is followed by in vivo and in vitro verifications for selected gene and CRAE pair.

KEY RESULTS

Our analysis revealed specific germline mutations linked to Grade 2 (or higher) chemotherapy-induced thrombocytopenia (CIT) and nausea/vomiting (CINV). Notably, both CRAEs were associated with mutations in the DLG5 gene. We found that DLG5 mutations related to CIT were associated with increased gene expression, while those associated with CINV were linked to suppressed gene expression, as indicated by the Genotype-Tissue Expression (GTEX) database. In megakaryocytes, overexpression of human DLG5 suppressed the hippo signalling pathway and induced YAP expression. In zebrafish, overexpression of human DLG5 not only reduced platelet production but also inhibited thrombus formation. Subsequent qPCR analysis revealed that DLG5 overexpression affected genes involved in cytoskeleton formation and alpha-granule formation, which could impact the normal generation of proplatelets.

CONCLUSION AND IMPLICATIONS

We identified a series of germline mutations associated with susceptibility to CIT and CINV. Of particular interest, we demonstrated that induced and suppressed DLG5 expression is respectively related to CIT and CINV. These findings shed light on the involvement of the hippo signalling pathway and DLG5 in the development of CRAEs, providing valuable insights into potential targets for therapeutic interventions.

Sex influence on serotonergic modulation of the vascular noradrenergic drive in rats

BACKGROUND AND PURPOSE

In male rats, the serotonergic system modulates sympathetic outflow at vascular levels, causing sympatho-inhibition and sympatho-excitation, mainly via 5-HT1D/1A and 5-HT3 receptors, respectively. However, sex influence on vascular serotonergic regulation has not yet been elucidated. This study aimed to analyse the 5-HT sympatho-modulatory role in female rats, characterising the 5-HT receptors involved.

EXPERIMENTAL APPROACH

Female Wistar (14- to 16-week-old) rats were prepared for sympathetic stimulation. Mean blood pressure (MBP) and heart rate (HR) were continuously measured. Vasopressor responses were obtained by electrical stimulation of the sympathetic outflow (0.1-5 Hz) or i.v. noradrenaline (0.01-0.5 μg·kg-1). 5-HT-related drug effects on adrenergic system were determined. Age-matched male rats were used as control.

KEY RESULTS

Basal MBP in females was lower than in male rats, whereas electrical-induced increases in MBP were similar. In females, 5-HT exerted a dose-dependent inhibition on the sympathetic-evoked vasoconstrictions, that was reproduced by some agonists; 5-CT (5-HT1/5/7) and L-694,247 (5-HT1D), whereas the selective 5-HT2A/2B/2C (α-methyl-5-HT) and 5-HT3 agonist (1-PBG) increased the electrically-produced vasopressor responses. None of the other drugs tested (targeting 5-HT1A/1B/1F, 5-HT2B/2C, 5-HT4, 5-HT5A or 5-HT7) modified these vasoconstrictions. Only 1-PBG (5-HT3) modified the vasoconstrictions induced by exogenous noradrenaline.

CONCLUSIONS AND IMPLICATIONS

In female rats, vascular serotonergic sympatholytic effects are due to prejunctional 5-HT1D receptor activation, whereas pre and/or postjunctional 5-HT3 and prejunctional 5-HT2A receptor activation is involved in the potentiating effect of vascular sympathetic neurotransmission. These findings may open novel sex-differential therapeutic strategies for treating cardiovascular conditions.

Mu-opioid receptors in tachykinin-1-positive cells mediate the respiratory and antinociceptive effects of the opioid fentanyl

BACKGROUND AND PURPOSE

Opioid drugs are potent analgesics that carry the risk of respiratory side effects due to actions on μ-opioid receptors (MORs) in brainstem regions that control respiration. Substance P is encoded by the Tac1 gene and is expressed in neurons regulating breathing, nociception, and locomotion. Tac1-positive cells also express MORs in brainstem regions mediating opioid-induced respiratory depression. We determined the role of Tac1-positive cells in mediating the respiratory effects of opioid drugs.

EXPERIMENTAL APPROACH

In situ hybridization was used to determine Oprm1 mRNA expression (gene encoding MORs) in Tac1-positive cells in regions regulating respiratory depression by opioid drugs. Conditional knockout mice lacking functional MORs in Tac1-positive cells were produced and the respiratory and locomotor responses to the opioid analgesic fentanyl were assessed using whole-body plethysmography. A tail immersion assay was used to assess the antinociceptive response to fentanyl.

KEY RESULTS

Oprm1 mRNA was highly expressed (>80%) in subpopulations of Tac1-positive cells in the preBötzinger Complex, nucleus tractus solitarius, and Kölliker-Fuse/lateral parabrachial region. Conditionally knocking out MORs in Tac1-positive cells abolished the effects of fentanyl on respiratory rate, relative tidal volume, and relative minute ventilation compared with control mice. Importantly, the antinociceptive response of fentanyl was eliminated in mice lacking functional MORs in Tac1-positive cells, whereas locomotor effects induced by fentanyl were preserved.

CONCLUSIONS AND IMPLICATIONS

Our findings suggest that Tac1-positive cells mediate the respiratory depressive and antinociceptive effects of the opioid fentanyl, providing important insights for the development of pain therapies with reduced risk of respiratory side effects.

The activated caveolin-3/μ-opioid receptor complex drives morphine-induced rescue therapy in failing hearts

BACKGROUND AND PURPOSE

Opioid analgesics can alleviate ischaemia/reperfusion (I/R) injury in chronic heart failure. However, the underlying mechanisms and targets remain unknown. Here, we investigate if caveolin-3 (Cav3) interacts with μ opioid receptors and if Cav3-μ receptor interactions play a role in morphine-induced cardioprotection in failing hearts.

EXPERIMENTAL APPROACH

Cav3 and μ receptor proteins in human and rat heart tissue were determined by western blot, immunofluorescence and co-immunoprecipitation. Methyl-β-cyclodextrin (MβCD), a destroyer of caveolae, and AAV-Cav3 shRNA were used to reduce Cav3 expression in failing rat hearts. CTOP, a specific μ antagonist, was administrated before morphine preconditioning in perfused failing heart models of myocardial I/R injury.

KEY RESULTS

Levels of Cav3 and μ receptor proteins were significantly higher in human and rat myocardial tissues with heart failure than in control tissues. Cav3 and μ receptor expression levels were positively correlated with disease severity. The signal of the cardiac Cav3 protein was colocalized with μ receptor in both the human and rat heart sections. Disruption of caveolae in the failing heart by either MβCD or AAV-Cav3 shRNA significantly inhibits morphine-induced phosphorylation of ERK1/2 and cardioprotection. Administration of CTOP substantially reduced Cav3 expression and morphine-induced cardioprotective effect in heart failure.

CONCLUSION AND IMPLICATIONS

Our data suggest that up-regulation of the Cav3/μ receptor complex is critical for morphine protection of the failing heart against I/R injury by regulating the ERK1/2 pathway. The activated Cav3/μ receptor complex is an understudied therapeutic target for opioid treatment of heart failure and ischaemic insult.

A systematic assessment of robustness in CNS safety pharmacology

BACKGROUND AND PURPOSE

Irwin tests are key preclinical study elements for characterising drug-induced neurological side effects. This multicentre study aimed to assess the robustness of Irwin tests across multinational sites during three stages of protocol harmonisation. The projects were part of the Enhanced Quality in Preclinical Data framework, aiming to increase success rates in transition from preclinical testing to clinical application.

EXPERIMENTAL APPROACH

Female and male NMRI mice were assigned to one of three groups (vehicle, MK-801 0.1 and 0.3 mg kg-1). Irwin scores were assessed at baseline and multiple times following intraperitoneal injection of MK-801 using local protocols (Stage 1), shared protocols with harmonised environmental design (Stage 2) and fully harmonised Irwin scoring protocols (Stage 3).

KEY RESULTS

The analysis based on the four functional domains (motor, autonomic, sedation and excitation) revealed substantial data variability in Stages 1 and 2. Although there was still marked overall heterogeneity between sites in Stage 3 after complete harmonisation of the Irwin scoring scheme, heterogeneity was only moderate within functional domains. When comparing treatment groups versus vehicle, we found large effect sizes in the motor domain and subtle to moderate effects in the excitation-related and autonomic domains.

CONCLUSION AND IMPLICATIONS

The pronounced interlaboratory variability in Irwin datasets for the CNS-active compound MK-801 needs to be carefully considered when making decisions during drug development. While environmental and general study design had a minor impact, the study suggests that harmonisation of parameters and their scoring can limit variability and increase robustness.

Cognitive improvement via cortical cannabinoid receptors and choline-containing lipids

BACKGROUND AND PURPOSE

Recent research linking choline-containing lipids to degeneration of basal forebrain cholinergic neurons in neuropathological states illustrates the challenge of balancing lipid integrity with optimal acetylcholine levels, essential for memory preservation. The endocannabinoid system influences learning and memory processes regulated by cholinergic neurotransmission. Therefore, we hypothesised that activation of the endocannabinoid system may confer neuroprotection against cholinergic degeneration.

EXPERIMENTAL APPROACH

We examined the neuroprotective potential of sub-chronic treatments with the cannabinoid agonist WIN55,212-2, using ex vivo organotypic tissue cultures including nucleus basalis magnocellularis and cortex and in vivo rat models of specific cholinergic damage induced by 192IgG-saporin. Levels of lipids, choline and acetylcholine were measured with histochemical and immunofluorescence assays, along with [35S]GTPγS autoradiography of cannabinoid and muscarinic GPCRs and MALDI-mass spectrometry imaging analysis. Learning and memory were assessed by the Barnes maze and the novel object recognition test in rats and in the 3xTg-AD mouse model.

KEY RESULTS

Degeneration, induced by 192IgG-saporin, of baso-cortical cholinergic pathways resulted in memory deficits and decreased cortical levels of lysophosphatidylcholines (LPC). WIN55,212-2 restored cortical cholinergic transmission and LPC levels via activation of cannabinoid receptors. This activation altered cortical lipid homeostasis mainly by reducing sphingomyelins in lesioned animals. These modifications were crucial for memory recovery.

CONCLUSION AND IMPLICATIONS

We hypothesise that WIN55,212-2 facilitates an alternative choline source by breaking down sphingomyelins, leading to elevated cortical acetylcholine levels and LPCs. These results imply that altering choline-containing lipids via activation of cannabinoid receptors presents a promising therapeutic approach for dementia linked to cholinergic dysfunction.

Gpr55 deficiency crucially alters cardiomyocyte homeostasis and counteracts angiotensin II induced maladaption in female mice

BACKGROUND AND PURPOSE

Cannabis stimulates several G-protein-coupled-receptors and causes bradycardia and hypotension upon sustained consumption. Moreover, in vitro studies suggest an interference of cannabinoid-signalling with cardiomyocyte contractility and hypertrophy. We aimed at revealing a functional contribution of the cannabinoid-sensitive receptor GPR55 to cardiomyocyte homeostasis and neurohumorally induced hypertrophy in vivo.

EXPERIMENTAL APPROACH

Gpr55-/- and wild-type (WT) mice were characterized after 28-day angiotensin II (AngII; 1·μg·kg-1 min-1) or vehicle infusion. In isolated adult Gpr55-/- and WT cardiomyocytes, mitochondrial function was assessed under naïve conditions, while cytosolic Ca2+ handling was additionally determined following application of the selective GPR55 antagonist CID16020046.

KEY RESULTS

Gpr55 deficiency did not affect angiotensin II (AngII) mediated hypertrophic growth, yet, especially in females, it alleviated maladaptive pro-hypertrophic and -inflammatory gene expression and improved inotropy and adrenergic responsiveness compared to WT. In-depth analyses implied increased cytosolic Ca2+ concentrations and transient amplitudes, and accelerated sarcomere contraction kinetics in Gpr55-/- myocytes, which could be mimicked by GPR55 blockade with CID16020046 in female WT cells. Moreover, Gpr55 deficiency up-regulated factors involved in glucose and fatty acid transport independent of the AngII challenge, accelerated basal mitochondrial respiration and reduced basal protein kinase (PK) A, G and C activity and phospholemman (PLM) phosphorylation.

CONCLUSIONS AND IMPLICATIONS

Our study suggests GPR55 as crucial regulator of cardiomyocyte hypertrophy and homeostasis presumably by regulating PKC/PKA-PLM and PKG signalling, and identifies the receptor as potential target to counteract maladaptation, adrenergic desensitization and metabolic shifts as unfavourable features of the hypertrophied heart in females.

Dihydro-resveratrol ameliorates NLRP3 inflammasome-mediated neuroinflammation via Bnip3-dependent mitophagy in Alzheimer's disease

BACKGROUND AND PURPOSE

Dihydro-resveratrol (DHR), a polyphenol derivative, that has been demonstrated to suppress inflammation-mediated injury. However, it is still unknown whether it has anti-neuroinflammatory and neuroprotective effects, and a therapeutic action in Alzheimer's disease (AD).

EXPERIMENTAL APPROACH

The anti-inflammatory and anti-Alzheimer's disease actions of dihydro-resveratrol were investigated using lipopolysaccharide (LPS) and AD mice models, and primary microglial cells. The changes in behaviour in mice were detected by the Morris water maze test and open-field test. Flow cytometry assay, western blotting, immunofluorescence assays and co-immunoprecipitation were used to investigate the changes in the NLRP3 inflammasome activation and mitophagy.

KEY RESULTS

In this study, in vivo observations indicated that the administration of dihydro-resveratrol (DHR) dramatically restored spatial learning, memory ability, autophagy and mitophagy, attenuated NLRP3 inflammasome activation, neuroinflammation and amyloid precursor protein pathology in LPS mice and AD mice. In addition, the inhibition of autophagy and mitophagy, or the activation of NLRP3 in vivo greatly abolished DHR-generated therapeutic efficacy on neuroinflammation, amyloid precursor protein pathology and cognitive loss. Further examination indicated that the application of DHR after the LPS and ATP exposure significantly inhibited the NLRP3 inflammasome activation, neuroinflammation and enhanced autophagic and mitophagic activation in microglia. Additionally, in vitro results show that DHR protects microglial cells against LPS and ATP-induced cytotoxicity by inhibiting NLRP3 inflammasome through activating Bnip3-dependent mitophagy and ULK phosphorylation.

CONCLUSIONS AND IMPLICATIONS

In summary, these findings suggest that dihydro-resveratrol (DHR) possesses potent anti-neuroinflammatory property and can act as a potential therapeutic agent for the treatment of AD.

Elesclomol rescues mitochondrial copper deficiency in disease models without triggering cuproptosis

Copper (Cu) is an essential cofactor for metalloenzymes such as cytochrome c oxidase (CcO), the terminal enzyme of the mitochondrial electron transport chain. Mutations that directly or indirectly prevent Cu transport to mitochondria result in lethal pediatric diseases, such as Menkes disease. There is no clinically approved treatment for Menkes disease. We recently discovered that an investigational chemotherapy drug, elesclomol (ES), when complexed with Cu (ES-Cu), rescues mitochondrial Cu deficiency, activates CcO, and prevents perinatal lethality in a mouse model of Menkes disease. However, ES-Cu also has the potential to trigger cuproptosis, a type of Cu-dependent cell death. Therefore, to develop ES-Cu as a therapeutic agent for Menkes disease, it is critical to determine the therapeutic index of ES-Cu in Cu-deficient models. To this end, we used a Cu-deficient rat cardiomyocyte cell line and a mottled-brindled mouse model of severe Menkes disease to determine the toxicity and efficacy of ES-Cu. Our cell culture studies demonstrated that the EC50 of ES-Cu is ∼50-fold lower than IC50. Moreover, the biomarkers of Cu toxicity, including lipoylated proteins and a subset of iron-sulfur cluster-containing proteins of mitochondria, are activated only when ES-Cu is used at ∼10-fold to 25-fold higher than its EC50. Importantly, none of these biomarkers are activated in mottled-brindled mice treated with therapeutic doses of ES-Cu. Our study shows that ES-Cu can deliver Cu to CcO both in vitro and in vivo without triggering cuproptosis, a finding that could facilitate its use in Cu deficiency disorders, such as Menkes disease. SIGNIFICANCE STATEMENT: Genetic copper (Cu) deficiency causes lethal pediatric diseases, such as Menkes disease, which lacks approved treatment. Recently, the therapeutic potential of elesclomol (ES), a Cu-transporting chemotherapeutic drug, in a mouse model of Menkes disease has been reported. Because of the potential risk of Cu-induced toxicity from ES-Cu, it is crucial to determine its therapeutic index. Here, the biomarkers of ES-Cu efficacy and toxicity in Cu-deficient disease models were measured to demonstrate that ES-Cu can restore cuproenzymes without triggering toxicity biomarkers.

Astrocyte-Derived Interleukin 11 Modulates Astrocyte-Microglia Crosstalk via Nuclear Factor-κB Signaling Pathway in Sepsis-Associated Encephalopathy

Sepsis-associated encephalopathy (SAE) is a severe and frequent septic complication, characterized by neuronal damage as key pathological features. The astrocyte-microglia crosstalk in the central nervous system (CNS) plays important roles in various neurological diseases. However, how astrocytes interact with microglia to regulate neuronal injury in SAE is poorly defined. In this study, we aim to investigate the molecular basis of the astrocyte-microglia crosstalk underlying SAE pathogenesis and also to explore the new therapeutic strategies targeting this crosstalk in this devastating disease. We established a human astrocyte/microglia coculture system on a microfluidic device, which allows real-time and high-resolution recording of glial responses to inflammatory stimuli. Based on this microfluidic system, we can test the responses of astrocytes and microglia to lipopolysaccharide (LPS) treatment, and identify the molecular cues that mediate the astrocyte-microglia crosstalk underlying the pathological condition. In addition, the SAE mouse model was utilized to determine the state of glial cells and evaluate the therapeutic effect of drugs targeting the astrocyte-microglia crosstalk in vivo. Here, we found that activated astrocytes and microglia exhibited close spatial interaction in the SAE mouse model. Upon LPS exposure for astrocytes, we detected that more microglia migrated to the central astrocyte culture compartment on the microfluidic device, accompanied by M1 polarization and increased cell motility in microglia. Cytokine array analysis revealed that less interleukin 11 (IL11) was secreted by astrocytes following LPS treatment, which further promoted reprogramming of microglia to pro-inflammatory M1 phenotype via the nuclear factor-κB (NF-κB) signaling pathway. Intriguingly, we found that IL11 addition markedly rescued LPS-induced neuronal injuries on the microfluidic system and brain injury in the SAE mouse model. This study defines an unknown crosstalk of astrocyte-microglia mediated by IL11, which contributed to the neuropathogenesis of SAE, and suggested a potential therapeutic value of IL11 in the devastating disease.

Deacetylation of BAP31 by sirtuin 2 attenuates apoptosis of hepatocytes induced by endoplasmic reticulum stress, in chronic alcoholic liver injury

BACKGROUND AND PURPOSE

Endoplasmic reticulum (ER) stress is a crucial pathogenic mechanism in alcoholic liver disease (ALD). B-cell receptor-associated protein 31 (BAP31) can regulate ER homeostasis and anti-apoptosis, but the function and regulation of BAP31 in ALD are unclear. The purpose of this study is to investigate whether BAP31 deacetylation by sirtuin 2 could attenuate ER stress and apoptosis during ALD and to explore whether carnosol could alleviate ALD through the sirtuin 2/BAP31 pathway.

EXPERIMENTAL APPROACH

A mouse model of ALD was established by feeding mice with alcoholic liquid chow. In vitro, AML-12 cells were stimulated with alcohol. The therapeutic efficacy of carnosol in protecting mice from ALD pathogenesis was evaluated.

KEY RESULTS

Treatment with carnosol protected mice against ALD and attenuated hepatocyte ER stress and apoptosis. Carnosol up-regulated sirtuin 2 expression, and sirtuin 2knockdown abolished the protective effect of carnosol during ALD. Moreover, sirtuin 2 knockdown reduced BAP31 expression. Carnosol-mediated BAP31 up-regulation was abolished upon knockdown of sirtuin 2. Mechanistically, sirtuin 2 selectively regulates the deacetylation of BAP31 at K158.

CONCLUSION AND IMPLICATIONS

Taken together, the present study shows for the first time that carnosol exerts its protective efficacy through facilitating sirtuin 2-mediated deacetylation of BAP31 at K158 to attenuate hepatocyte ER stress and apoptosis during ALD. These results provide new therapeutic targets and approaches for combating chronic ALD.

TRPC6 suppresses liver fibrosis by inhibiting hepatic stellate cell activation via CaMK4-CREB pathway

BACKGROUND AND PURPOSE

Genetic ablation or inhibition of the cation channel TRPC6 is protective against renal, cardiac and intestinal fibrosis. However, TRPC6 expression is decreased in patients with liver diseases. Here, we explored the role of TRPC6 in liver fibrosis and the underlying mechanism.

EXPERIMENTAL APPROACH

Bile duct ligation and thioacetamide gavage were used to model liver fibrosis in C57BL/6J mice. Western blotting, immunolabelling and qPCR were employed for protein and mRNA expression. Liver injury/fibrosis were assessed using serum alanine transaminase and aspartate transaminase assays, haematoxylin-eosin, Masson and Sirius red staining. Adenoviruses were used to overexpress TRPC6 and CREB1Y134F. ChIP and dual-luciferase reporter assays were performed to test the direct inhibition of Acta2 transcription by CREB.

KEY RESULTS

TRPC6 protein levels were decreased in fibrotic liver tissues from both patients and mice, with the decrease being more robust in fibrotic areas. In hepatic stellate cells (HSCs), TRPC6 ablation aggravated liver injury and fibrosis, which was alleviated by overexpressing TRPC6. In primary cultured HSCs, deletion of TRPC6 exacerbated self-activation of HSCs, which was reversed by restoration of TRPC6 expression. Mechanistically, TRPC6 suppressed HSC activation through CaMK4-mediated CREB phosphorylation. CREB directly interacted with the promoter region of Acta2 to inhibit its transcription. Expression of a constitutively active form of CREB1 (CREB1Y134F) in HSCs attenuated BDL-induced liver injury/fibrosis in TRPC6 knockout mice.

CONCLUSION AND IMPLICATIONS

Deficiency of TRPC6 aggravates liver injury/fibrosis through augmentation of HSC activation. Increasing TRPC6 expression/function would be therapeutically beneficial for fibrotic liver diseases.

miR-210 as a therapeutic target in diabetes-associated endothelial dysfunction

BACKGROUND AND PURPOSE

MicroRNA (miR)-210 function in endothelial cells and its role in diabetes-associated endothelial dysfunction are not fully understood. We aimed to characterize the miR-210 function in endothelial cells and study its therapeutic potential in diabetes.

EXPERIMENTAL APPROACH

Two different diabetic mouse models (db/db and Western diet-induced), miR-210 knockout and transgenic mice, isolated vessels and human endothelial cells were used.

KEY RESULTS

miR-210 levels were lower in aortas isolated from db/db than in control mice. Endothelium-dependent relaxation (EDR) was impaired in aortas from miR-210 knockout mice, and this was restored by inhibiting miR-210 downstream protein tyrosine phosphatase 1B (PTP1B), mitochondrial glycerol-3-phosphate dehydrogenase 2 (GPD2), and mitochondrial oxidative stress. Inhibition of these pathways also improved EDR in both diabetic mouse models. High glucose reduced miR-210 levels in endothelial cells and impaired EDR in mouse aortas, effects that were reversed by overexpressing miR-210. However, plasma miR-210 levels were not affected in individuals with type 2 diabetes (T2D) following improved glycaemic status. Of note, genetic overexpression using miR-210 transgenic mice and pharmacological overexpression using miR-210 mimic in vivo ameliorated endothelial dysfunction in both diabetic mouse models by decreasing PTP1B, GPD2 and oxidative stress. Genetic overexpression of miR-210 altered the aortic transcriptome, decreasing genes in pathways involved in oxidative stress. miR-210 mimic restored decreased nitric oxide production by high glucose in endothelial cells.

CONCLUSION AND IMPLICATIONS

This study unravels the mechanisms by which down-regulated miR-210 by high glucose induces endothelial dysfunction in T2D and demonstrates that miR-210 serves as a novel therapeutic target.

LINKED ARTICLES

This article is part of a themed issue Non-coding RNA Therapeutics. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v182.2/issuetoc.

Differential participation of CaMKII/ROCK and NOS pathways in the cholinergic inhibitory drive operated by nicotinic α7 receptors in perisynaptic Schwann cells

Nicotinic α7 receptors (α7 nAChRs) present in perisynaptic Schwann cells (PSCs) control acetylcholine (ACh) spillover from the neuromuscular synapse by transiently increasing intracellular Ca2+, which fosters adenosine release via type 1 equilibrative nucleoside transporters (ENT1) and retrograde activation of presynaptic A1 inhibitory receptors. The putative Ca2+-dependent pathways downstream α7 nAChRs involved in the sensing inhibitory drive operated by PSCs is unknown. Herein, we used phrenic nerve-hemidiaphragm preparations from Wistar rats. Time-lapse video-microscopy was instrumental to assess nerve-evoked (50-Hz bursts) transmitter exocytosis and intracellular NO oscillations in nerve terminals and PSCs loaded with FM4-64 and DAF-FM diacetate fluorescent dyes, respectively. Selective activation of α7 nAChRs with PNU 282987 reduced transmitter exocytosis (FM4-64 dye unloading) during 50-Hz bursts. Inhibition of calmodulin activity (with W-7), Ca2+/calmodulin-dependent protein kinase II (CaMKII; with KN-62) and Rho-kinase (ROCK; with H1152) all prevented the release inhibitory effect of PNU 282987. The α7 nAChR agonist transiently increased NO inside PSCs; the same occurred during phrenic nerve stimulation with 50-Hz bursts in the presence of the cholinesterase inhibitor, neostigmine. The nitric oxide synthase (NOS) inhibitor, L-NOARG, but not with the guanylylcyclase (GC) inhibitor, ODQ, prevented inhibition of transmitter exocytosis by PNU 282987. Inhibition of adenosine kinase with ABT 702 favors the intracellular accumulation and translocation of the nucleoside to the synaptic cleft, thus overcoming prevention of the PNU 282987 effect caused by H1152, but not by L-NOARG. In conclusion, the α7nAChR-mediated cholinergic inhibitory drive operated by PSCs involves two distinct Ca2+-dependent intracellular pathways: a CaMKII/ROCK cascade along with a GC-independent NO pathway with divergent end-effects concerning ADK inhibition.

Chronic ethanol exposure in mice evokes pre- and postsynaptic deficits in GABAergic transmission in ventral tegmental area GABA neurons

BACKGROUND AND PURPOSE

GABAergic neurons in mouse ventral tegmental area (VTA) exhibit elevated activity during withdrawal following chronic ethanol exposure. While increased glutamatergic input and decreased GABAA receptor sensitivity have been implicated, the impact of inhibitory signaling in VTA GABA neurons has not been fully addressed.

EXPERIMENTAL APPROACH

We used electrophysiological and ultrastructural approaches to assess the impact of chronic intermittent ethanol vapour exposure in mice on GABAergic transmission in VTA GABA neurons during withdrawal. We used CRISPR/Cas9 ablation to mimic a somatodendritic adaptation involving the GABAB receptor (GABABR) in ethanol-naïve mice to investigate its impact on anxiety-related behaviour.

KEY RESULTS

The frequency of spontaneous inhibitory postsynaptic currents was reduced in VTA GABA neurons following chronic ethanol treatment and this was reversed by GABABR inhibition, suggesting chronic ethanol strengthens the GABABR-dependent suppression of GABAergic input to VTA GABA neurons. Similarly, paired-pulse depression of GABAA receptor-dependent responses evoked by optogenetic stimulation of nucleus accumbens inputs from ethanol-treated mice was reversed by GABABR inhibition. Somatodendritic currents evoked in VTA GABA neurons by GABABR activation were reduced following ethanol exposure, attributable to the suppression of GIRK (Kir3) channel activity. Mimicking this adaptation enhanced anxiety-related behaviour in ethanol-naïve mice.

CONCLUSIONS AND IMPLICATIONS

Chronic ethanol weakens the GABAergic regulation of VTA GABA neurons in mice via pre- and postsynaptic mechanisms, likely contributing to their elevated activity during withdrawal and expression of anxiety-related behaviour. As anxiety can promote relapse during abstinence, interventions targeting VTA GABA neuron excitability could represent new therapeutic strategies for treatment of alcohol use disorder.

White Tea Reduces Dyslipidemia, Inflammation, and Oxidative Stress in the Aortic Arch in a Model of Atherosclerosis Induced by Atherogenic Diet in ApoE Knockout Mice

Objective: In this study, we aimed to evaluate the potential effects of white tea (WT) in the atherosclerosis process characterized by oxidative stress, inflammation, and dyslipidemia. Methods: In our study, apolipoprotein E knockout (ApoE-/-) mice (RRID: IMSR_JAX:002052) and C57BL/6J mice (RRID: IMSR_JAX:000664) were used. In the atherosclerosis model induced by an atherogenic diet (AD), WT was administered via oral gavage at two different concentrations. The animals were sacrificed by decapitation under anesthesia, and their serum and aortic tissues were collected. Total cholesterol (TC), triglyceride (TG), interleukin (IL)-1β, IL-6, IL-10, IL-12, tumor necrosis factor-α (TNF-α), interferon-γ, myeloperoxidase, paraoxonase-1, lipoprotein-associated phospholipase A2, oxidized low-density lipoprotein (Ox-LDL), lectin-like oxidized LDL receptor (LOX-1), a disintegrin, and metalloprotease (ADAM) 10 and 17 activities were determined via colorimetric, enzyme-linked immunoassay, and fluorometric methods. Results: WT supplementation decreased serum Ox-LDL, LOX-1, TC, and TG levels by approximately 50%. TNF- and IL-6 levels were reduced by approximately 30% in the aortic arch. In addition, ADAM10/17 enzyme activities were found to be reduced by approximately 25%. However, no change in the AD-induced fibrotic cap structure was observed in the aortic root. Conclusions: The findings indicate that white tea effectively reduced oxidative stress, inflammation, and dyslipidemia in atherosclerosis but does not affect atheroma plaque morphology.

A combination of peripherally restricted CB1 and CB2 cannabinoid receptor agonists reduces bladder afferent sensitisation in cystitis

Cannabinoid agonists can potentially ameliorate lower urinary tract symptoms (LUTS), including pain associated with interstitial cystitis/bladder pain syndrome (IC/BPS). This study aims to determine the contributions of the cannabinoid 1 receptors (CB1Rs) and CB2Rs in regulating the activity of different functional classes of afferents, comparing normal healthy bladder with bladders from guinea pigs with protamine/zymosan-induced cystitis. The mechanosensitivity of different functional afferent classes was determined by ex vivo single-unit extracellular recordings. Peripherally restricted CB1R preferential agonists, ACEA and PrNMI and peripherally restricted CB2R selective agonists, 4Q3C and olorinab all reduced the mechanosensitivity of mucosal bladder afferents. The potency and efficacy of these synthetic cannabinoid agonists were significantly increased in cystitis compared to controls. Combined application of CB1R agonists, ACEA or PrNMI with the CB2R agonist, 4Q3C produced additive inhibitory effects. ACEA and PrNMI also inhibited the stretch-induced firing of high-threshold muscular bladder afferents in animals with cystitis. In contrast, low- and high-threshold muscular-mucosal bladder afferents were unaffected by the CB1R and CB2R agonists in control and cystitis. Our data indicated that peripherally restricted CB1R and CB2R agonists effectively reduce the sensitisation of probable nociceptive afferents in the bladder in cystitis. The findings also suggest a potential benefit of simultaneously targeting both the CB1Rs and CB2Rs to ameliorate LUTS in cystitis.

AMP-activated protein kinase in the amygdala and hippocampus contributes to enhanced fear memory in diabetic mice

BACKGROUND AND PURPOSE

Diabetic patients have an increased risk of psychiatric disorders. Because hyperglycaemia increases L-lactate in the brain and L-lactate inhibits AMP-activated protein kinase (AMPK), this study investigated the role of L-lactate and AMPK in strengthened fear memory, a model for human psychiatric disorders, in diabetic mice.

EXPERIMENTAL APPROACH

The diabetic model was mice injected with streptozotocin. Fear memory was measured using the conditioned fear test with low (0.45 mA) or high (0.50 mA) foot shock to cause low and high freezing, respectively. Protein levels of AMPK and phosphorylated AMPK (pAMPK) were measured by western blotting and immunohistochemistry.

KEY RESULTS

At 0.45 mA, the AMPK inhibitor dorsomorphin increased freezing, which was inhibited by the AMPK activator acadesine. In contrast, at 0.50 mA, acadesine decreased freezing, which was inhibited by dorsomorphin. In diabetic mice, pAMPK was decreased in the amygdala and hippocampus. Diabetic mice showed increased freezing at 0.45 mA, which was inhibited by acadesine. In the amygdala and hippocampus, L-lactate was increased in diabetic mice and injection of L-lactate into non-diabetic mice increased freezing at 0.45 mA. In addition, L-lactate decreased pAMPK in the hippocampus, but not the amygdala, and increase in freezing induced by L-lactate was inhibited by acadesine. Dorsomorphin-induced increase in freezing was inhibited by the AMPA receptor antagonist NBQX.

CONCLUSIONS AND INTERPRETATION

In diabetic mice, L-lactate is increased in the amygdala and hippocampus, possibly through hyperglycaemia, which strengthens fear memory through inhibition of AMPK and activation of glutamatergic function.

Elucidating the beneficial impact of exercise on chronic obstructive pulmonary disease and its comorbidities: Integrating proteomic and immunological insights

BACKGROUND AND PURPOSE

Physical activity is an effective therapeutic protocol for treating chronic obstructive pulmonary disease (COPD). However, the mechanisms underlying the benefits of physical activity in COPD are not fully elucidated.

EXPERIMENTAL APPROACH

In a mouse model of COPD, analysis of biological markers and lung proteomics identified the molecular pathways through which exercise ameliorates COPD.

KEY RESULTS

Exercise improved pulmonary function, emphysema, small airway disease, pulmonary inflammation, glucose metabolic dysregulation, and insulin resistance in COPD mice. Proteomic analysis revealed 430 differentially expressed proteins (DEPs) between the COPD and COPD + Exercise (COPD + Ex) groups. GO analysis indicated that the enriched pathways were predominantly related to the immune response, inflammatory processes, insulin secretion, and glucose metabolic processes. GO analysis revealed IL-33 as a crucial target for the exercise-related amelioration of COPD. KEGG analysis showed that DEPs were significantly enriched in primary immunodeficiency, the intestinal immune network for IgA production, and the NF-κB signalling pathway. Exercise inhibited NF-κB activation by suppressing the CD14/TLR4/MyD88 and TNF-α/TNF-R1/TRAF2/5 pathways in COPD mice. Exercise inhibited expression of BCR, IgM, IgD, IgG, IgE, and IgA by suppressing B-cell receptor signalling. Exercise attenuated glucose metabolic dysregulation and insulin resistance through the suppression of proinflammatory mediators, including MHC I, MHC II, TNF-α, IFN-γ, and IL-1β, while concurrently increasing insulin expression. The qRT-PCR results were consistent with the proteomic results.

CONCLUSION AND IMPLICATIONS

In a mouse model, exercise improved COPD and its metabolic comorbidities through immune system regulation and inflammation suppression, offering insights into potential therapeutic targets.

Vortioxetine reduces the development of pain-related behaviour in a knee osteoarthritis model in rats: Involvement of nerve growth factor (NGF) down-regulation

BACKGROUND AND PURPOSE

Vortioxetine, a multimodal-acting antidepressant, has recently shown analgesic properties. We aimed to investigate its prophylactic effect in the osteoarthritis (OA) model and gain insights into the underlying molecular mechanisms. Duloxetine was studied as a reference.

EXPERIMENTAL APPROACH

In the monoiodoacetate (MIA)-induced rat model of knee OA, pain-related behaviour was assessed in weight-bearing and Von Frey tests. Antidepressants were administered orally once daily for 28 days. Gene expression of pain-related mediators (Ngf, Il-1β, Tnf-α, Bdnf, and Tac1 encoding substance P) and oxidative stress parameters were determined after completion of the treatment/behavioural testing protocol.

KEY RESULTS

Vortioxetine and duloxetine dose dependently reduced weight-bearing asymmetry and mechanical hyperalgesia of the paw ipsilateral to the MIA-injected knee. Vortioxetine reduced the increased Ngf mRNA expression in the MIA-injected knees to the level in sham-injected counterparts. It reduced oxidative stress parameters in the affected knees, more effectively in females than males. Duloxetine showed no effect on Ngf mRNA expression and oxidative stress. Both antidepressants decreased mRNA expression of pain-related mediators in the lumbar L3-L5 ipsilateral DRGs and spinal cords, which were up-regulated in MIA-injected rats. This effect was male-specific.

CONCLUSION AND IMPLICATIONS

Vortioxetine may be effective against the development of chronic pain in OA. Its antihyperalgesic effect may be mediated, at least in part, by normalization of NGF expression in the affected joint. Decrease of localized oxidative stress and of expression of pain-related mediators that contribute to central sensitization are also involved in vortioxetine's antihyperalgesic effect, in a sex-specific pattern.

Characterization of novel nitazene recreational drugs: Insights into their risk potential from in vitro µ-opioid receptor assays and in vivo behavioral studies in mice

2-Benzylbenzimidazole derivatives or 'nitazenes' are increasingly present on the recreational drug market. Here, we report the synthesis and pharmacological characterization of 15 structurally diverse nitazenes that might be predicted to emerge or grow in popularity. This work expands the existing knowledge about 2-benzylbenzimidazole structure-activity relationships (SARs), while also helping stakeholders (e.g., forensic toxicologists, clinicians, policymakers) in their risk assessment and preparedness for the potential next generation of nitazenes. In vitro µ-opioid receptor (MOR) affinity was determined via competition radioligand (3[H]DAMGO) binding assays in rat brain tissue. MOR activation (potency and efficacy) was studied by means of a cell-based β-arrestin 2 recruitment assay. For seven nitazenes, including etonitazene, opioid-like pharmacodynamic effects (antinociception, locomotor activity, body temperature changes) were evaluated after subcutaneous administration in male C57BL/6 J mice. The results showed that all nitazenes bound to MOR with nanomolar affinities, and the functional potency of several of them was comparable to or exceeded that of fentanyl. In vivo, dose-dependent effects were observed for antinociception, locomotor activity, and body temperature changes in mice. SAR insights included the high opioid-like activity of methionitazene, iso-butonitazene, sec-butonitazene, and the etonitazene analogues 1-ethyl-pyrrolidinylmethyl N-desalkyl etonitazene and ethylene etonitazene. The most potent analogue of the panel across all functional assays was α'-methyl etonitazene. Taken together, through critical pharmacological evaluation, this work provides a framework for strengthened preparedness and risk assessments of current and future nitazenes that have the potential to cause harm to users.

Tetrabenazine, a vesicular monoamine transporter 2 inhibitor, inhibits vesicular storage capacity and release of monoamine transmitters in mouse brain tissue

BACKGROUND AND PURPOSE

Tetrabenazine (TBZ), used for treating hyperkinetic disorders, inhibits vesicular monoamine transporter-2 (VMAT-2), which sequesters monoamines into vesicles for exocytosis. However, our knowledge of the effect of TBZ on monoaminergic transmission is limited. Herein, we provide neurochemical evidence regarding the effect of VMAT-2 inhibition on vesicular neurotransmitter release from the prefrontal cortex (PFC) and striatum (STR) (brain regions involved in characteristic TBZ treatment side effects). The interaction between TBZ and MDMA was also assessed regarding motor behaviour in mice.

EXPERIMENTAL APPROACH

Vesicular storage capacity and release of [3H]-noradrenaline ([3H]-NA), [3H]-dopamine ([3H]-DA), [3H]-serotonin ([3H]-5-HT), and [3H]-acetylcholine ([3H]-ACh) was studied in mouse PFC and STR ex vivo slice preparations using electrical field stimulation. Additionally, locomotor activity was assessed in vehicle-treated mice and compared with that of MDMA, TBZ, and co-administered animals (n = 6) using the LABORAS system.

KEY RESULTS

TBZ lowered the storage capacity and inhibited the vesicular release of [3H]-NA and [3H]-DA from the PFC, and [3H]-DA and [3H]-5-HT from the STR in a concentration-dependent manner. Unlike vesamicol (vesicular ACh uptake inhibitor), TBZ failed to inhibit the vesicular release of [3H]-ACh from the PFC. When the vesicular storage of the investigated monoamines was inhibited by TBZ in the PFC and STR, MDMA induced the release of transmitters through transporter reversal; MDMA dose dependently increased locomotor activity in vivo.

CONCLUSION AND IMPLICATIONS

Our observations provide neurochemical evidence explaining the mechanism of VMAT-2 inhibitors in the brain and support the involvement of dopaminergic and noradrenergic transmission in hyperkinetic movement disorders.

Serotonergic transmission plays differentiated roles in the rapid and sustained antidepressant-like effects of ketamine

BACKGROUND AND PURPOSE

The emerging antidepressant effects of ketamine have inspired tremendous interest in its underlying neurobiological mechanisms, although the involvement of 5-HT in the antidepressant effects of ketamine remains unclear.

EXPERIMENTAL APPROACH

The chronic restraint stress procedure was performed to induce depression-like behaviours in mice. OFT, FST, TST, and NSFT tests were used to evaluate the antidepressant-like effects of ketamine. Tph2 knockout or depletion of 5-HT by PCPA and 5,7-DHT were used to manipulate the brain 5-HT system. ELISA and fibre photometry recordings were used to measure extracellular 5-HT levels in the brain.

KEY RESULTS

60 min after injection, ketamine (10 mg·kg-1, i.p.) produced rapid antidepressant-like effects and increased brain 5-HT levels. After 24 h, ketamine significantly reduced immobility time in TST and FST tests and increased brain 5-HT levels, as measured by ELISA and fibre photometry recordings. The sustained (24 h) but not rapid (60 min) antidepressant-like effects of ketamine were abrogated by PCPA and 5,7-DHT, or by Tph2 knockout. Importantly, NBQX (10 mg·kg-1, i.p.), an AMPA receptor antagonist, significantly inhibited the effect of ketamine on brain 5-HT levels and abolished the sustained antidepressant-like effects of ketamine in naïve or CRS-treated mice.

CONCLUSION AND IMPLICATIONS

This study confirms the requirement of serotonergic neurotransmission for the sustained antidepressant-like effects of ketamine, which appears to involve AMPA receptors, and provides avenues to search for antidepressant pharmacological targets.

Sex differences in the metabolic activation of and platelet response to vicagrel in mice: Androgen as a key player

As a biological variable, sex influences the metabolism of and/or response to certain drugs. Vicagrel is being developed as an investigational new drug in China; however, it is unknown whether sex could affect its metabolic activation and platelet responsiveness. This study aimed to determine whether such differences could exist, and to elucidate the mechanisms involved. Orchiectomized (ORX) or ovariectomized (OVX) mouse models were used to investigate the effects of androgens or estrogens on the metabolic activation of and platelet response to vicagrel. Plasma vicagrel active metabolite H4 concentrations, platelet inhibition of vicagrel, and protein levels of intestinal hydrolases Aadac and Ces2 were measured, respectively. Further, p38-MAPK signaling pathway was enriched, whose role was determined using SB202190. Results showed that female mice exhibited significantly elevated systemic exposure of H4 and enhanced platelet responses to vicagrel than males, and that protein expression levels of Aadac and Ces2 differed by sex. OVX mice exhibited less changes than sham mice. ORX mice exhibited increases in protein levels of intestinal hydrolases, systemic exposure of H4, and platelet inhibition of vicagrel, but dihydrotestosterone (DHT) reversed these changes in ORX mice and suppressed these changes in OVX mice. Phosphorylated p38 levels were reduced in female or ORX mice but increased in ORX mice by DHT. SB202190 reversed DHT-induced changes observed in ORX mice. We concluded that sex differences exist in metabolic activation of and platelet response to vicagrel in mice through elevation of p38 phosphorylation by androgens, suggesting sex-based vicagrel dosage adjustments for patient care.

A novel inhibitor of class IIa histone deacetylases attenuates collagen-induced arthritis

BACKGROUND AND PURPOSE

Most inhibitors of histone deacetylases (HDACs) are not selective and are cytotoxic. Some have anti-inflammatory activity in disease models, but cytotoxicity prevents long-term uses in non-fatal diseases. Inhibitors selective for class IIa HDACs are much less cytotoxic and may have applications in management of chronic inflammatory diseases.

EXPERIMENTAL APPROACH

LL87 is a novel HDAC inhibitor examined here for HDAC enzyme selectivity. It was also investigated in macrophages for cytotoxicity and for inhibition of lipopolysaccharide (LPS)-stimulated cytokine secretion. In a rat model of collagen-induced arthritis, LL87 was investigated for effects on joint inflammation in Dark Agouti rats. Histological, immunohistochemical, micro-computed tomography and molecular analyses characterise developing arthritis and anti-inflammatory efficacy.

KEY RESULTS

LL87 was significantly more inhibitory against class IIa than class I or IIb HDAC enzymes. In macrophages, LL87 was not cytotoxic and reduced both LPS-induced secretion of pro-inflammatory cytokines, and IL6-induced class IIa HDAC activity. In rats, LL87 attenuated paw swelling and clinical signs of arthritis, reducing collagen loss and histological damage in ankle joints. LL87 decreased immune cell infiltration, especially pro-inflammatory macrophages and osteoclasts, into synovial joints and significantly reduced expression of pro-inflammatory cytokines and tissue-degrading proteases.

CONCLUSION AND IMPLICATIONS

A novel inhibitor of class IIa HDACs has been shown to have an anti-inflammatory and anti-arthritic profile distinct from current therapies. It is efficacious in reducing macrophage infiltration and joint inflammation in a chronic model of rat arthritis.

Contribution of T-type calcium channel isoforms to cold and mechanical sensitivity in naïve and oxaliplatin-treated mice of both sexes

BACKGROUND AND PURPOSE

The chemotherapy agent oxaliplatin can give rise to oxaliplatin-induced peripheral neuropathy (OIPN). Here, we investigated whether T-type calcium channels (Cav3) contribute to OIPN.

EXPERIMENTAL APPROACH

We chronically treated mice with oxaliplatin and assessed pain responses and changes in expression of Cav3.2 calcium channels. We also tested the effects of T-type channel blockers on cold sensitivity in wild-type and Cav3.2 null mice.

KEY RESULTS

Oxaliplatin treatment led to mechanical and cold hypersensitivity in male and female mice. Mechanical hypersensitivity persisted in Cav3.2 null mice of both sexes. Intraperitoneal or intrathecal delivery of pan T-type channel inhibitors attenuated mechanical hypersensitivity in wild-type but not Cav3.2 null mice. Remarkably cold hypersensitivity occurred in female but not male Cav3.2 null mice even without oxaliplatin treatment. Unexpectedly, intrathecal, intraplantar or intraperitoneal delivery of T-type channel inhibitors Z944 or TTA-P2 transiently induced cold hypersensitivity in both male and female wild-type mice. Acute knockdown of specific Cav3 isoforms revealed that the depletion of Cav3.1 in males and depletion of either Cav3.1 or Cav3.2 in females triggered cold hypersensitivity. Finally, reducing Cav3.2 expression by disrupting the interactions between Cav3.2 and the deubiquitinase USP5 with the small organic molecule II-2 reversed oxaliplatin-induced mechanical and cold hypersensitivity and importantly did not trigger cold allodynia.

CONCLUSION AND IMPLICATIONS

Altogether, our data indicate that T-type channels differentially contribute to the regulation of cold and mechanical hypersensitivity, and raise the possibility that T-type channel blockers could promote cold allodynia.

A p75 neurotrophin receptor-sparing nerve growth factor protects retinal ganglion cells from neurodegeneration by targeting microglia

BACKGROUND AND PURPOSE

Retinal ganglion cells (RGCs) are the output stage of retinal information processing, via their axons forming the optic nerve (ON). ON damage leads to axonal degeneration and death of RGCs, and results in vision impairment. Nerve growth factor (NGF) signalling is crucial for RGC operations and visual functions. Here, we investigate a new neuroprotective mechanism of a novel therapeutic candidate, a p75-less, TrkA-biased NGF agonist (hNGFp) in rat RGC degeneration, in comparison with wild type human NGF (hNGFwt).

EXPERIMENTAL APPROACH

Both neonate and adult rats, whether subjected or not to ON lesion, were treated with intravitreal injections or eye drops containing either hNGFp or hNGFwt. Different doses of the drugs were administered at days 1, 4 or 7 after injury for a maximum of 10 days, when immunofluorescence, electrophysiology, cellular morphology, cytokine array and behaviour studies were carried out. Pharmacokinetic evaluation was performed on rabbits treated with hNGFp ocular drops.

RESULTS

hNGFp exerted a potent RGC neuroprotection by acting on microglia cells, and outperformed hNGFwt in rescuing RGC degeneration and reducing inflammatory molecules. Delayed use of hNGFp after ON lesion resulted in better outcomes compared with treatment with hNGFwt. Moreover, hNGFp-based ocular drops were less algogenic than hNGFwt. Pharmacokinetic measurements revealed that biologically relevant quantities of hNGFp were found in the rabbit retina.

CONCLUSIONS AND IMPLICATIONS

Our data point to microglia as a new cell target through which NGF-induced TrkA signalling exerts neuroprotection of the RGC, emphasizing hNGFp as a powerful treatment to tackle retinal degeneration.

An adenosinergic positive feedback loop extends pharmacological cardioprotection duration

BACKGROUND AND PURPOSE

Adenosine receptor activation induces delayed, sustained cardioprotection against ischaemia-reperfusion (IR) injury (24-72 h), but the mechanisms underlying extended cardioprotection duration remain unresolved. We hypothesized that a positive feedback loop involving adenosine receptor-induced proteasomal degradation of adenosine kinase (ADK) and decreased myocardial adenosine metabolism extends the duration of cardioprotection.

EXPERIMENTAL APPROACH

Mice were administered an ADK inhibitor, ABT-702, to induce endogenous adenosine signalling. Cardiac ADK protein and mRNA levels were analysed 24-120 h later. Theophylline or bortezomib was administered 24 h after ABT-702 to examine the late roles of adenosine receptors or proteasomal activity, respectively, in ADK expression and cardioprotection at 72 h. Coronary flow and IR tolerance were analysed by Langendorff technique. The potential for continuous adenosinergic cardioprotection was examined using heterozygous, cardiac-specific ADK KO (cADK+/-) mice. Cardiac ADK expression was also examined after A1 or A3 receptor agonist, phenylephrine, lipopolysaccharide or sildenafil administration.

KEY RESULTS

ABT-702 treatment decreased ADK protein content and provided cardioprotection from 24 to 72 h. ADK mRNA upregulation restored ADK protein after 96-120 h. Adenosine receptor or proteasome inhibition at 24 h reversed ABT-702-induced ADK protein deficit and cardioprotection at 72 h. cADK+/- hearts exhibited continuous cardioprotection. Diverse preconditioning agents also diminished cardiac ADK protein expression.

CONCLUSION AND IMPLICATIONS

A positive feedback loop driven by adenosine receptor-induced ADK degradation and renewed adenosine signalling extends the duration of cardioprotection by ABT-702 and possibly other preconditioning agents. The therapeutic potential of continuous adenosinergic cardioprotection is demonstrated in cADK+/- hearts.

Immune regulatory and anti-resorptive activities of tanshinone IIA sulfonate attenuates rheumatoid arthritis in mice

BACKGROUND AND PURPOSE

Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation and painful joint destruction. Current treatments are helpful in RA remission, but strong immunosuppressive activity and patient resistance are clinical issues. This study explores a dual-action inhibitor, possessing both anti-inflammatory and anti-resorptive properties, as a novel treatment for RA.

EXPERIMENTAL APPROACH

Therapeutic efficacy and mechanisms of ectosteric (tanshinone IIA sulfonate [T06]) and active site-directed (odanacatib [ODN]) inhibitors of cathepsin K (CatK) were evaluated in RA mouse models. Pathology was assessed through biochemical analyses and histopathological examination. Flow cytometry analysis was performed to characterize immune cells. Anti-inflammatory effects of T06 on nuclear factor kappa beta (NF-κB) pathway were studied in macrophages.

KEY RESULTS

T06 effectively lowered the number of joint-resident immune cells, accompanied by significantly reduced production of inflammatory cytokines and collagenolytic proteases. This also included the suppression of Th17 cells and IL-17, resulting in the reduction of osteoclasts in arthritic joints and amplification of the overall anti-resorptive effect of T06, which has been attributed to its selective inhibition of the collagenolytic activity of CatK by preventing its oligomerization. The anti-inflammatory mechanism of T06 was based on blocking the phosphorylation of IκBα in the NF-κB pathway, resulting in reduced activation and expression of inflammatory cytokines. In contrast, ODN had no effect on inflammation and disease progression and was limited to the inhibition of CatK.

CONCLUSIONS

The combined anti-resorptive and anti-inflammatory activities characterize T06 as a novel therapeutic agent for RA.

Effects of a pro-resolving drug in COVID-19: preclinical studies to a randomized, placebo-controlled, phase Ib/IIa trial in hospitalized patients

INTRODUCTION

Pro-resolving molecules may curb disease caused by viruses without altering the capacity of the host to deal with infection. AP1189 is a melanocortin receptor-biased agonist endowed with pro-resolving and anti-inflammatory activity. We evaluated the preclinical and early clinical effects of treatment with AP1189 in the context of COVID-19.

METHODS

C57BL/6j mice were infected intranasally with MHV-A59 or hK18-ACE2 mice with SARS-CoV-2. AP1189 (10 mg·kg-1, BID, s.c.) was given to the animals from day 2 and parameters evaluated at day 5. Human PBMCs from health donors were infected with SARS-CoV-2 in presence or absence of AP1189 and production of cytokines quantified. In the clinical study, 6 patients were initially given AP1189 (100 mg daily for 14 days) and this was followed by a randomized (2:1), placebo-controlled, double-blind trial that enrolled 54 hospitalized COVID-19 patients needing oxygen support. The primary outcome was the time in days until respiratory recovery, defined as a SpO2 ≥ 93% in ambient air.

RESULTS

Treatment with AP1189 attenuated pulmonary inflammation in mice infected with MHV-A59 or SARS-CoV-2 and decreased the release of CXCL10, TNF-α and IL-1β by human PBMCs. Hospitalized COVID-19 patients already taking glucocorticoids took a median time of 6 days until respiratory recovery when given placebo versus 4 days when taking AP1189 (P = 0.017).

CONCLUSION

Treatment with AP1189 was associated with less disease caused by beta-coronavirus infection both in mice and in humans. This is the first demonstration of the effects of a pro-resolving molecule in the context of severe infection in humans.

Schwann cell transient receptor potential ankyrin 1 (TRPA1) ortholog in zebrafish larvae mediates chemotherapy-induced peripheral neuropathy

BACKGROUND AND PURPOSE

The oxidant sensor transient receptor potential ankyrin 1 (TRPA1) channel expressed by Schwann cells (SCs) has recently been implicated in several models of neuropathic pain in rodents. Here we investigate whether the pro-algesic function of Schwann cell TRPA1 is not limited to mammals by exploring the role of TRPA1 in a model of chemotherapy-induced peripheral neuropathy (CIPN) in zebrafish larvae.

EXPERIMENTAL APPROACH

We used zebrafish larvae and a mouse model to test oxaliplatin-evoked nociceptive behaviours. We also performed a TRPA1 selective silencing in Schwann cells both in zebrafish larvae and mice to study their contribution in oxaliplatin-induced CIPN model.

KEY RESULTS

We found that zebrafish larvae and zebrafish TRPA1 (zTRPA1)-transfected HEK293T cells respond to reactive oxygen species (ROS) with nociceptive behaviours and intracellular calcium increases, respectively. TRPA1 was found to be co-expressed with the Schwann cell marker, SOX10, in zebrafish larvae. Oxaliplatin caused nociceptive behaviours in zebrafish larvae that were attenuated by a TRPA1 antagonist and a ROS scavenger. Oxaliplatin failed to produce mechanical allodynia in mice with Schwann cell TRPA1 selective silencing (Plp1+-Trpa1 mice). Comparable results were observed in zebrafish larvae where TRPA1 selective silencing in Schwann cells, using the specific Schwann cell promoter myelin basic protein (MBP), attenuated oxaliplatin-evoked nociceptive behaviours.

CONCLUSION AND IMPLICATIONS

These results indicate that the contribution of the oxidative stress/Schwann cell/TRPA1 pro-allodynic pathway to neuropathic pain models seems to be conserved across the animal kingdom.

PDE4B inhibition by nerandomilast: Effects on lung fibrosis and transcriptome in fibrotic rats and on biomarkers in human lung epithelial cells

BACKGROUND AND PURPOSE

The PDE4 family is considered a prime target for therapeutic intervention in several fibro-inflammatory diseases. We have investigated the molecular mechanisms of nerandomilast (BI 1015550), a preferential PDE4B inhibitor.

EXPERIMENTAL APPROACH

In addition to clinically relevant parameters of idiopathic pulmonary fibrosis (IPF; lung function measurement/high-resolution computed tomography scan/AI-Ashcroft score), whole-lung homogenates from a therapeutic male Wistar rat model of pulmonary fibrosis were analysed by next-generation sequencing (NGS). Data were matched with public domain data derived from human IPF samples to investigate how well the rat model reflected human IPF. We scored the top counter-regulated genes following treatment with nerandomilast in human single cells and validated disease markers discovered in the rat model using a human disease-relevant in vitro assay of IPF.

KEY RESULTS

Nerandomilast improved the decline of lung function parameters in bleomycin-treated animals. In the NGS study, most transcripts deregulated by bleomycin treatment were normalised by nerandomilast treatment. Most notably, a significant number of deregulated transcripts that were identified in human IPF disease were also found in the animal model and reversed by nerandomilast. Mapping to single-cell data revealed the strongest effects on mesenchymal, epithelial and endothelial cell populations. In a primary human epithelial cell culture system, several disease-related (bio)markers were inhibited by nerandomilast in a concentration-dependent manner.

CONCLUSIONS AND IMPLICATIONS

This study further supports the available knowledge about the anti-inflammatory/antifibrotic mechanisms of nerandomilast and provides novel insights into the mode of action and signalling pathways influenced by nerandomilast treatment of lung fibrosis.

Translational modelling to predict human pharmacokinetics and pharmacodynamics of a Bruton's tyrosine kinase-targeted protein degrader BGB-16673

BACKGROUND AND PURPOSE

Bifunctional small molecule degraders, which link the target protein with E3 ubiquitin ligase, could lead to the efficient degradation of the target protein. BGB-16673 is a Bruton's tyrosine kinase (BTK) degrader. A translational PK/PD modelling approach was used to predict the human BTK degradation of BGB-16673 from preclinical in vitro and in vivo data.

EXPERIMENTAL APPROACH

A simplified mechanistic PK/PD model was used to establish the correlation between the in vitro and in vivo BTK degradation by BGB-16673 in a mouse model. Human and mouse species differences were compared using the parameters generated from in vitro human or mouse blood, and human or mouse serum spiked TMD-8 cells. Human PD was then predicted using the simplified mechanistic PK/PD model.

KEY RESULTS

BGB-16673 showed potent BTK degradation in mouse whole blood, human whole blood, and TMD-8 tumour cells in vitro. Furthermore, BGB-16673 showed BTK degradation in a murine TMD-8 xenograft model in vivo. The PK/PD model predicted human PD and the observed BTK degradation in clinical studies both showed robust BTK degradation in blood and tumour at clinical dose range.

CONCLUSION AND IMPLICATIONS

The presented simplified mechanistic model with reduced number of model parameters is practically easier to be applied to research projects compared with the full mechanistic model. It can be used as a tool to better understand the PK/PD behaviour for targeted protein degraders and increase the confidence when moving to the clinical stage.

Ginsenoside Rg1 enriches gut microbial indole-3-acetic acid to alleviate depression-like behavior in mice via oxytocin signaling

BACKGROUND AND PURPOSE

Although a large collection of data has shown that ginsenosides, the major active ingredients from Ginseng, have neuroprotective and anti-depressant effect, the mechanism of action is incompletely understood. This study aims to elucidate the antidepressant mechanism of ginsenoside Rg1 (Rg1), a poorly absorbed ginsenoside, from the perspective of gut microbe to brain signaling.

METHODS

A mouse model of depression was induced by unpredictable mild stress (UMS). Behavioral and neurochemical tests were conducted to evaluate the effect and mechanism of Rg1 on depressive behavior. Non-target and target metabolomics were performed to identify the signaling metabolites underlying the antidepressant efficacy of Rg1. Gut microbial structure was analyzed by 16S rRNA sequencing and the potential functional strains associated with Rg1 action were investigated by in vitro bacterial culture. Chemical intervention was used to explore the mechanism of Rg1 and signaling metabolite.

RESULTS

Rg1 improved UMS-induced despair, anxiety-like and social avoidance behaviors in mice, which were accompanied by increased hypothalamic oxytocin secretion and restored neural proliferation in the hippocampus. Metabolomic analysis of the gut-brain axis revealed that Rg1 increased the concentration of serum and brain indole-3-acetic acid (IAA), a bacterial metabolite that was partially attributed to the enrichment of Lactobacillus murinus in the gut microbiome. Oral supplementation of IAA mimicked the anti-depressant action of Rg1, while oxytocin receptor antagonist abrogated the anti-depressant effects of both Rg1 and IAA.

CONCLUSION

Our work provides a new gut-to-brain signaling mechanism for the antidepressant effects of Rg1. In particular, Rg1 enriches the abundance of Lactobacillus murinus, which in turn increases the level of brain IAA and potentiates hypothalamic oxytocin signal. These findings suggest a promising pathway for producing antidepressant effects through gut-brain crosstalk.

The plant extract PNS mitigates atherosclerosis via promoting Nrf2-mediated inhibition of ferroptosis through reducing USP2-mediated Keap1 deubiquitination

BACKGROUND AND PURPOSE

Atherosclerosis is the basis of cardiovascular disease. Ferroptosis is a form of programmed cell death characterized by lipid peroxidation, which contributes to atherogenesis. The plant extract PNS (Panax notoginseng saponins), containing the main active ingredients of Panax notoginseng, exhibits anti-atherogenic properties. Herein, we determined whether PNS and its major components could attenuate atherosclerosis by suppressing ferroptosis and revealed the underlying mechanism(s).

EXPERIMENTAL APPROACH

The anti-atherogenic effects of PNS and their association with inhibition of ferroptosis was determined in apoE-/- mice. In vitro, the anti-ferroptotic effect and mechanism(s) of PNS components were demonstrated in the presence of ferroptosis inducers. Expression of ferroptosis markers and the ubiquitination of Keap1 were evaluated in USP2-/- macrophages. Finally, the anti-atherogenic effect of USP2 knockout was determined by using USP2-/- mice treated with high-fat diet (HFD) and AAV-PCSK9.

KEY RESULTS

PNS inhibited ferroptosis and atherosclerosis in vivo. PNS suppressed ferroptosis and ferroptosis-aggravated foam cell formation and inflammation in vitro. Mechanistically, PNS and its components activated Nrf2 by antagonizing Keap1, which was attributed to the inhibition of USP2 expression. USP2 knockout antagonized ferroptosis and ferroptosis-aggravated foam cell formation and inflammation, thus mitigating atherosclerosis. USP2 knockout abolished inhibitory effects of PNS on foam cell formation and inflammation in vitro.

CONCLUSION AND IMPLICATIONS

PNS reduced USP2-mediated Keap1 de-ubiquitination and promoted Keap1 degradation, thereby activating Nrf2, improving iron metabolism and reducing lipid peroxidation, thus contributing to an anti-atherosclerotic outcome. Our study revealed the mechanism(s) underlying inhibition of ferroptosis and atherosclerosis by PNS.

Oroxylin A attenuates psoriasiform skin inflammation by direct targeting p62 (sequestosome 1) via suppressing M1 macrophage polarization

BACKGROUND AND PURPOSE

Psoriasis results from the interplay of innate and adaptive immunity in the skin. Oroxylin A (OA) has shown anti-inflammatory effects in various disorders. This study explores oroxylin A potential in treating psoriasis, particularly its impact on type I macrophage (Mφ1) polarization.

EXPERIMENTAL APPROACH

Oroxylin A-mediated therapeutic effects were evaluated using imiquimod-induced or IL-23-injected psoriatic mice models, followed by proteomics assays to predict potential signalling and targeting proteins. Immunofluorescence and immunoblot assays verified that oroxylin A suppresses NF-κB signalling in Mφ1 macrophages. Co-immunoprecipitation and microscale thermophoresis (MST) assays further demonstrated that p62 (sequestosome 1) is the target protein for oroxylin A in macrophages. Oroxylin A-p62-mediated suppression of psoriasis was validated in an imiquimod-induced p62 conditional knockout (cKO) mice model.

KEY RESULTS

Oroxylin A demonstrated therapeutic efficacy in murine models induced by imiquimod or IL-23 by attenuating cutaneous inflammation and mitigating Mφ1 polarization via NF-κB signalling. Proteomics analysis suggested SQSTM1/p62 as a key target, confirmed to interact directly with oroxylin A. Oroxylin A disrupted the p62-PKCζ interaction by binding to PB1 domain of p62. Its anti-inflammatory effects were significantly reduced in macrophages from p62 cKO mice compared to the wild-type (WT) mice in psoriasis model, supporting oroxylin A role in suppressing Mφ1 polarization through its interaction with p62.

CONCLUSION AND IMPLICATIONS

Our findings demonstrated oroxylin A suppressed psoriasiform skin inflammation in mouse models by blocking the PKCζ-p62 interaction, subsequently inhibiting the activation of NF-κB p65 phosphorylation in macrophages.

Selective modulation of epileptic tissue by an adenosine A3 receptor-activating drug

BACKGROUND AND PURPOSE

Adenosine, through the A1 receptor (A1R), is an endogenous anticonvulsant. The development of adenosine receptor agonists as antiseizure medications has been hampered by their cardiac side effects. A moderately A1R-selective agonist, MRS5474, has been reported to suppress seizures without considerable cardiac action. Hypothesizing that this drug could act through other than A1R and/or through a disease-specific mechanism, we assessed the effect of MRS5474 on the hippocampus.

EXPERIMENTAL APPROACH

Excitatory synaptic currents, field potentials, spontaneous activity, [3H]GABA uptake and GABAergic currents were recorded from rodent or human hippocampal tissue. Alterations in adenosine A3 receptor (A3R) density in human tissue were assessed by Western blot.

KEY RESULTS

MRS5474 (50-500 nM) was devoid of effect upon rodent excitatory synaptic signals in hippocampal slices, except when hyperexcitability was previously induced in vivo or ex vivo. MRS5474 inhibited GABA transporter type 1 (GAT-1)-mediated γ-aminobutyric acid (GABA) uptake, an action not blocked by an A1R antagonist but blocked by an A3R antagonist and mimicked by an A3R agonist. A3R was overexpressed in human hippocampal tissue samples from patients with epilepsy that had focal resection from surgery. MRS5474 induced a concentration-dependent potentiation of GABA-evoked currents in oocytes micro-transplanted with human hippocampal membranes prepared from epileptic hippocampal tissue but not from non-epileptic tissue, an action blocked by an A3R antagonist.

CONCLUSION AND IMPLICATIONS

We identified a drug that activates A3R and has selective actions on epileptic hippocampal tissue. This underscores A3R as a promising target for the development of antiseizure medications.