British Journal of Pharmacology最新文献

Background and purpose: Subsets of midbrain dopamine (DA) neurons express the vesicular glutamate transporter VGLUT2 and can release the excitatory neurotransmitter glutamate. VGLUT2⁺ DA neurons of the substantia nigra pars compacta (SNc) were shown to be more resistant to neurodegeneration in animal models of Parkinson's disease (PD). Additionally, there is evidence that VGLUT2⁺ DA neurons are enriched in the SNc of patients with PD, suggesting that VGLUT2 expression may confer resilience to DA neurons not only in animal models but also in the human disease. It remains unclear whether VGLUT2⁺ DA neurons are simply selected over VGLUT2^- DA neurons during degeneration or whether VGLUT2 can also emerge de novo upon neuronal stress or injury.

Experimental approach: We employed pharmacological models of reversible parkinsonism to determine whether acute DA depletion or DA receptor antagonism would increase VGLUT2⁺ DA neurons in the SNc. Additionally, we isolated striatal synaptic vesicles from Parkinsonian mice to test how glutamate affected vesicular DA uptake.

Key results: We found that acute depletion of DA or antagonism of D₂ receptors sufficed to increase the fraction of DA neurons expressing VGLUT2, suggesting that VGLUT2 can emerge in DA neurons de novo. Increased VGLUT2 expression resulted in enhanced vesicular DA uptake in the presence of glutamate.

Conclusions and implication: Our work provides evidence that VGLUT2 expression is induced in DA neurons under conditions of hypodopaminergia or D₂ receptor antagonism. VGLUT2 emergence in DA neurons may be a compensatory strategy when DA levels are low and/or DA receptor signalling is compromised.

Background and purpose: Lifestyle is closely related to major depressive disorder (MDD). Given the growing focus on the impact of diet on mental health, this study examined how dietary habits affect the pathophysiology of MDD.

Experimental approach: Health check-up data were analysed. Mice received sucrose under chronic unpredictable mild stress (CUMS) and were evaluated by behavioural, neurochemical and metabolic analysis.

Key results: Health check-up data showed increased sucrose intake in MDD patients. When mice received sucrose under CUMS, hyperactivity and aggression were attenuated, although social deficits or behavioural despair induced by CUMS persisted, and recognition memory was impaired. The behavioural changes were associated with dysfunction of the locus coeruleus-prefrontal cortex circuit, caused by impaired noradrenaline release due to presynaptic α₂-adrenoceptor upregulation, and postsynaptic α₁-adrenoceptor and β₁-adrenoceptor downregulation. α₂-Adrenoceptor antagonism by atipamezole rescued behavioural changes induced by sucrose intake under CUMS, whereas α₂-adrenoceptor agonism by guanfacine in CUMS mice mimicked these behavioural changes. Among the antidepressants, mirtazapine effectively increased noradrenaline release and rescued behavioural changes induced by sucrose intake under CUMS. Sucrose intake under CUMS induced peripheral hyperglycaemia and dysregulation of central glucose metabolism. Glucose transporter inhibition by phloretin rescued behavioural changes induced by sucrose intake under CUMS. Intracerebroventricular and systemic streptozotocin administration reproduced these behavioural changes and α₂-adrenoceptor upregulation.

Conclusions and implications: Our findings suggest that the observed behavioural changes are associated with dysfunction of the noradrenergic α₂-adrenoceptor system induced by impaired glucose metabolism. These insights targeting the noradrenergic-metabolic axis might be a new strategy for sugar-induced depression subtypes.

Background and purpose: Pharmacological inhibition of TRPC4 and/or TRPC5 channels reduces Pavlovian aversion memory in stressed mice and reduces amygdala reactivity to aversion in humans with depression. The aims of this mouse study were to improve understanding of these anxiolytic processes, determine whether there are corrective effects on reward processes, and provide further translational evidence for TRPC4/C5 channel brain and neuron distribution.

Experimental approach: Mouse models of chronic social stress (CSS), with increased aversion and decreased reward responding, were applied to investigate the effects of a TRPC4/TRPC5 channel inhibitor. RT-qPCR and FISH were used to determine regional and neuronal gene expression.

Key results: Male mice underwent CSS, or were controls, and a TRPC4/TRPC5 inhibitor or vehicle was administered prior to Pavlovian aversion learning: stressed-vehicle mice displayed excessive Pavlovian learning, measured as high freezing to tone and context, and this was reduced by a TRPC4/TRPC5 inhibitor. Different stressed and control mice were tested on discriminative reward learning: there was no TRPC4/TRPC5 inhibitor effect on learning, but it did increase reward responding and effortful reward motivation in stressed mice. In naive male and female mice, Trpc4 and Trpc5 gene levels were moderate and high in glutamate principal neurons in basolateral amygdala and ventral hippocampus, respectively; co-expression with the CCKB receptor was substantial. TRPC4 and TRPC5 were expressed by glutamate neurons in human amygdala and hippocampus.

Conclusions and implications: This study furthers understanding of the therapeutic potential of TRPC4/TRPC5 channel inhibition for excessive aversion processing and impaired reward processing.

Background and purpose: Tumour-associated macrophages (TAMs) constitute the predominant cell population within the tumour microenvironment and play a crucial role in promoting the progression of primary hepatocellular carcinoma (HCC). Our previous study has identified PLAGL2 as a driver of HCC progression; however, the comprehensive regulation of PLAGL2 on the immunosuppressive microenvironment of HCC has not been fully elucidated. The objective of this study is to elucidate the molecular mechanism by which PLAGL2 regulates TAMs.

Experimental approach: Mouse orthotopic liver cancer, subcutaneous tumour, and in vitro co-culture models demonstrated PLAGL2's regulation of TAM recruitment/polarisation. Single-cell sequencing and Flow cytometry assessed immune cell subpopulation changes.

Key results: Our study found that the expression of PLAGL2 was positively correlated with the recruitment of TAMs, M2 polarisation and poor prognosis. PLAGL2 promoted macrophage migration and M2 polarisation in vitro and in vivo. Single-cell analysis revealed that overexpression of PLAGL2 in HCC cells mainly recruited CCR2⁺ macrophages. Deletion of macrophages attenuated the promotion of HCC growth by PLAGL2. Mechanistically, PLAGL2 directly participated in the transcriptional regulation of CCL2, thereby initiating its transcription and expression. Moreover, pharmacological inhibition of CCR2 significantly inhibited PLAGL2-induced HCC progression, TAM recruitment and M2 polarisation.

Conclusions and implications: PLAGL2 participates in the chemotaxis of TAMs and the regulation of M2 polarisation through the CCL2-CCR2 axis, thereby promoting an immunosuppressive microenvironment in HCC. Additionally, this study demonstrated that PLAGL2 serves as a novel transcription factor for CCL2, suggesting that PLAGL2 is a potential drug target for the treatment of HCC.

Background and purpose: The clinical success of small-molecule drugs in treating pancreatic and prostate cancer patients has been both promising and challenging. Whereas patients with advanced-stage tumours have significant initial responses to chemotherapy, many have experienced rapid resistance, metastasis and recurrence after curative-intent surgery. Traditional tubulin inhibitors are widely used in cancer treatment, but their effectiveness is often limited by drug resistance and toxicity. SB-216, a novel colchicine-binding site inhibitor (CBSI), has been reported to demonstrate potential efficacy in overcoming paclitaxel (PTX) resistance in a melanoma xenograft model (A375/TxR) and inhibiting spontaneous metastasis.

Experimental approach: We evaluated SB-216 as a therapeutic option for advanced malignancies, specifically castration-resistant prostate cancer (CRPC) and pancreatic ductal adenocarcinoma (PDAC). We conducted preclinical evaluations of SB-216 in CRPC parental and taxane-resistant lines. Additionally, we investigated the effects of SB-216 on PDAC cells, xenograft models and patient-derived models.

Key results: In vitro, SB-216 potently induces G2/M phase cell cycle arrest, inhibits cell proliferation, colony formation and cell migration in a concentration-dependent manner. In vivo, SB-216 significantly attenuates tumour growth in prostate cancer xenograft models, overcomes PTX resistance and confers a survival benefit at a dose of 2 mg kg^-1 without affecting body weight. SB-216 also inhibits the growth of PDAC xenograft tumours and the growth of patient-derived cells and organoids.

Conclusions and implications: Our findings suggest that SB-216 is a promising candidate as a new generation of anti-mitotic agents for advanced cancer, and further exploration in combination with other agents is warranted.

Background and purpose: The intestine plays a key role in the initiation of sepsis. The gut barrier impedes the translocation of commensal bacteria to the liver in sepsis. Previous studies have reported that angiotensin-(1-7) [Ang-(1-7)] attenuated sepsis-induced organ injury and mortality. However, its role in sepsis-induced intestinal barrier dysfunction remains unclear. Here we have investigated therapeutic effects of Ang-(1-7) on the intestinal barrier dysfunction and dysbiosis in a murine model of sepsis.

Experimental approach: We used a model of sepsis in C57BL/6 mice with caecal ligation and puncture (CLP), to assess mortality and histological and biochemical changes in the gut and liver tissues. Faecal microbiota transplantation (FMT) was used to assess the role of the gut microbiome. 16-s rDNA and metabolomics analyses were performed to characterize differences in the gut microbiome signatures and metabolic profiles.

Key results: Plasma Ang-(1-7) was decreased in patients with sepsis. In CLP mice, exogenous Ang-(1-7) attenuated intestinal barrier dysfunction and liver damage. FMT experiments showed that the protective effects of Ang-(1-7) on the gut depended on the gut microbiota. Furthermore, 16-s ribosomal DNA analysis revealed that Ang-(1-7) treatment increased the abundance of Lactobacillus gasseri (L. gasseri) among commensal bacteria. Mechanistically, L. gasseri regulated the production of antimicrobial peptides in intestinal epithelia by activating NLRP6 inflammation.

Conclusion and implications: Ang-(1-7) protected against sepsis-induced intestine barrier dysfunction and liver injury in mice by modulating gut homeostasis and NLRP6 inflammasome. Ang-(1-7) is a promising candidate drug for protecting intestinal homeostasis in sepsis, offering new insights for clinical treatment.

Background and purpose: Interleukin (IL)-13 is implicated in airway hyperreactivity (AHR), a key feature of asthma. We explored the potential anti-AHR activity of selected specialised pro-resolving mediators (SPMs) in IL-13-induced AHR models, using human bronchial smooth muscle cells (BSMCs) and human isolated bronchi.

Experimental approach: Calcium flux responses induced by histamine or LTD₄ were assessed in BSMCs preconditioned with IL-13 and SPMs for 24 h. Human bronchi were isolated from lung tissue and preconditioned for 48 h in the presence or absence of IL-13 and SPMs. Concentration-response relationships for histamine and LTD₄ were established using myography to determine efficacy (E_max) and potency (pEC₅₀) following interventions.

Key results: In BSMCs, exposure to IL-13 increased calcium flux (E_max) triggered by histamine and LTD₄. Protectin D1 (PD1) and maresin 1 (MaR1) reversed this effect, but not lipoxin A₄, resolvin D2, and maresin-conjugate in tissue repair 3 (MCTR3). In bronchi, IL-13 exposure amplified contractions to histamine and LTD₄, and this enhancement was reversed by PD1 and MaR1. In contrast, PD1 and MaR1 added acutely during myography had no effect on agonist-induced contractility. PD1 attenuated IL-13-induced enhancement of airway contractions triggered by mast cell activation. CysLT₁ antagonism did not influence the anti-hyperreactive effect of SPMs. Chemo-informatics revealed structural similarities between PD1 and MaR1 that may explain the anti-hyperreactive action of these two SPMs.

Conclusion and implications: This new anti-hyperreactive action of PD1 and MaR1 encourages further research into their potential as therapies for the treatment of airway hyperreactivity.

Background and purpose: Anastrozole, an aromatase inhibitor, is used to treat postmenopausal women with hormone receptor-positive breast cancer, but also induces musculoskeletal pain and can lead to therapeutic regimen suspension. Aromatase inhibitors promote the release of pro-inflammatory substances from sensitised nerve fibres, which might lead to peripheral mast cell activation.

Experimental approach: We explore if tryptase released by peripheral mast cells could activate the protease-activated receptor 2 (PAR2) to sustain anastrozole-induced painful symptoms.

Key results: Anastrozole caused mechanical allodynia, muscle strength loss, and increased mast cell number and tryptase levels in the plantar tissue of male C57BL/6 mice. Depletion (using compound 48/80) or stabilisation (using ketotifen fumarate) of mast cells prevented anastrozole-induced mechanical allodynia and muscle strength loss. Compound 48/80 also prevented the increase in the number of mast cells in the plantar tissue. Tryptase inhibitors nafamostat and gabexate, or PAR2 inhibitors ENMD-1068 and AZ3451, reduced the anastrozole-induced mechanical allodynia and muscle strength loss. Furthermore, anastrozole did not cause mechanical allodynia and muscle strength loss in global (PAR2^-/-) or sensory neuron-specific (PAR2 Na_v 1.8^-/-) PAR2 knockout mice. Local sub-nociceptive doses of the PAR2 agonists (tryptase, trypsin or 2F) enhanced the anastrozole-induced mechanical sensitivity in wild-type mice, which was reduced by pre-treatment with AZ3451. PAR2^-/- or PAR2 Na_v 1.8^-/- mice treated with anastrozole did not respond to local sub-nociceptive doses of PAR2 agonists.

Conclusions and implications: Our results provide a new mechanism underlying anastrozole-induced pain, highlighting the mast cell/tryptase/PAR2 axis as a therapeutic target to manage painful symptoms.

Background and purpose: Immune tolerance prevents inflammation and autoimmunity, with dendritic cells (DCs) playing a key role. Reprogramming DCs towards a tolerogenic state represents a promising therapeutic strategy. Sulforaphane (SFN) has known immunomodulatory effects, but its clinical application is limited by poor stability and bioavailability. To enhance its therapeutic potential, SFN was conjugated with mannose (SFNMan) or fucose (SFNFuc), aiming to induce a tolerogenic phenotype in human monocyte-derived DCs (moDCs) under inflammation and to explore NFATc1's involvement.

Experimental approach: moDCs were exposed to inflammatory conditions and treated with SFN, SFNMan or SFNFuc. Their phenotype, cytokine profile, T cell-modulating capacity and NFATc1 signalling were evaluated.

Key results: SFNMan selectively induced a tolerogenic phenotype, characterised by an increased PD-L1/CD86 ratio and IL-10 production; up-regulation of SOCS1 and IDO transcripts; and Treg expansion and reduced proliferation of cytotoxic T cell proliferation. Functional assays and confocal microscopy revealed that SFNMan, but not SFNFuc, promoted NFATc1 nuclear translocation. Pharmacological inhibition of NFATc1 with cyclosporin A (CsA) abolished these effects, confirming NFATc1 as a central mediator of SFNMan-induced immune tolerance.

Conclusions and implications: Our findings identify NFATc1 as a key transcriptional switch in moDCs tolerogenic programming and highlight the carbohydrate-dependent specificity of SFN conjugates. SFNMan represents a novel carbohydrate-engineered immunomodulator capable of driving immune tolerance through NFATc1 activation. These results provide a mechanistic framework for the development of precision therapies targeting inflammatory and autoimmune diseases.