British Journal of Pharmacology最新文献

Background and purpose: Bruton tyrosine kinase (Btk) is essential for B cell function. Its role in myeloid cells is less understood. Greater insights into Btk significance in myeloid cells are needed to evaluate its potential as a therapeutic target during the effector phase of antibody-induced autoimmune diseases, where inhibiting autoantibody production suppresses tissue inflammation only after a delay. Such a situation can be observed, for example, in acute flares of pemphigoid diseases, a group of autoimmune blistering skin diseases.

Experimental approach: We examined the effect of neutrophil-specific Btk gene deficiency and of the Btk inhibitor ibrutinib on disease in the antibody-transfer model of bullous pemphigoid (BP)-like epidermolysis bullosa acquisita (EBA), a model that solely reflects the effector phase. We additionally investigated the effect of Btk inhibitors on responses of neutrophils relevant for autoimmune diseases in vitro.

Key results: Both neutrophil-specific Btk deficiency and ibrutinib administration, systemic or topical, markedly protected against skin inflammation and disrupted established inflammation. Stimulation of murine neutrophils with immune complexes activated Btk and induced the release of leukotriene B₄ (LTB₄) and reactive oxygen species (ROS). Btk deficiency abolished LTB₄ but not ROS release, indicating distinct signalling pathways regulating LTB₄ and ROS following Fcγ receptor activation.

Conclusions and implications: Our findings demonstrate that EBA skin inflammation is critically controlled by a Fcγ receptor-Btk-LTB₄ axis in neutrophils. This highlights Btk as promising drug target to treat EBA and potentially other antibody-induced autoimmune diseases.

Covalent fluorescent probes have emerged as versatile chemical tools to visualise active enzymes in complex biological systems. When tailored for specific applications, ranging from activity-based protein profiling for drug development to high spatiotemporal resolution imaging of enzymatic activities, these probes provide unique insights into rapid lipid metabolism. The recent development of reverse-designing optimised inhibitors into probes, together with improved analytical techniques, is rapidly advancing our ability to resolve enzyme function in great detail. In this mini-review, we summarise the current landscape of covalent fluorescent probes for the 2-arachidonoylglycerol (2-AG) metabolising enzymes (diacylglycerol lipase, monoacylglycerol lipase, ABHD6 and ABHD12), highlighting the discoveries they have enabled and discussing strategies to address gaps where probes remain lacking.

Background and purpose: Intervertebral disc degeneration (IVDD), a leading cause of low back pain, lacks effective disease-modifying therapies. Diabetes exacerbates IVDD risk, but the causal mechanisms and therapeutic potential of glucose-lowering agents remain underexplored. This study aimed to identify glucose-lowering drug targets strongly associated with IVDD using Mendelian randomisation (MR) and to validate the therapeutic efficacy and mechanisms of sitagliptin, an inhibitor of dipeptidyl peptidase 4 (DPP4), in alleviating IVDD progression.

Experimental approach: Two-sample MR analysis was performed to assess causal links between glucose-lowering drug targets and IVDD risk using genome-wide association studies data. A tail puncture model in male SD rats, interactive culture systems of nucleus pulposus (NP) cells and macrophages were established to evaluate effects of sitagliptin. Molecular techniques and network pharmacology were employed to elucidate mechanisms.

Key results: MR analysis identified DPP4 as a causal risk factor for IVDD. DPP4 expression was elevated in degenerated human and rat NP tissues. Sitagliptin alleviated disc height loss, preserved extracellular matrix (ECM) integrity, and reduced histological degeneration in vivo. Sitagliptin suppressed macrophage infiltration and interfered with polarisation. It disrupted the NF-κB/NLRP3/IL-1β axis in NP cells, attenuating inflammasome activation, pro-inflammatory cytokine release and ECM degradation.

Conclusion and implications: DPP4 was a causal driver of IVDD, and its inhibition by sitagliptin mitigated degeneration by disrupting the pathogenic positive feedback loop between macrophages and NP cells. These findings reposition sitagliptin, a clinically approved antidiabetic drug, as a promising therapeutic candidate for IVDD, highlighting the translational potential of targeting DPP4 and its downstream inflammatory cascades.

Background and purpose: The leukocyte-mediated innate inflammatory response is crucial for clearing ischaemic debris during myocardial infarction (MI). If unresolved, it leads to chronic inflammation and heart failure. While macrophages produce specialised pro-resolving mediators (SPMs) like maresin 1, the therapeutic potential of exogenous maresin 1 in cardiac repair remains unclear.

Experimental approach: Male C57BL/6J mice (8-12 weeks) subjected coronary artery ligation to induce MI. Mice received either low-dose (LD; 0.4 μg kg^-1) or high-dose (HD; 4 μg kg^-1) maresin 1 subcutaneously 3 h post-MI, continued through day 1 or day 5. Saline-injected mice served as MI controls, while non-infarcted mice were used as naïve controls.

Key results: LD-maresin 1 enhanced neutrophil clearance but did not improve cardiac function. However, HD-maresin 1 significantly improved cardiac performance, evidenced by higher fractional shortening and global longitudinal strain, and reducing LV and lung mass-to-body weight ratios. In infarcted myocardium, HD-maresin 1 up-regulated FPR2 receptor expression and increased levels of SPMs (RvD5, PD-1, maresin 1). Flow cytometry showed accelerated neutrophil clearance from the LV and spleen. Moreover, HD-maresin 1 also promoted a reparative macrophage phenotype, with expansion of Ly6C^lo cells and up-regulation of Mrc1 and Arg1. Furthermore, kidney immunohistochemistry showed reduced NGAL and increased nephrin expression, indicating attenuation of cardiorenal inflammation.

Conclusions and implications: High-dose maresin 1 activates FPR2 signalling and enhances the resolution of inflammation by modulating leukocyte dynamics and macrophage phenotype. Improving cardiac function and attenuating cardiorenal inflammation, highlighting the therapeutic potential of maresin 1 in cardiac healing and acute heart failure.

Background and purpose: Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive interstitial lung disease, mainly affecting adult males. Although it exhibits a primarily fibrosing imprint, it serves as a model for understanding inflammation-driven interstitial lung diseases that can evolve into PF. We analysed the interplay between inflammation and fibrosis, in relation to sex in a mouse model of PF.

Experimental approach: Adult C57BL/6 mice of both sexes were treated with subcutaneous bleomycin injection (3 times a week for 1-4 weeks). We used RT-PCR, western blotting and immunohistochemistry, along with ELISA, flow cytometry and mass spectrometry (UPLC-MS/MS) to analyse our results.

Key results: Male mice developed more severe fibrosis, with higher levels of collagen, and enhanced pulmonary epithelial-mesenchymal transition, compared with females. Males also showed early cell infiltration (neutrophils and macrophages) during the initial stages, followed by loss of lung architecture and an exacerbated development of fibrosis. In contrast, females exhibited physiological resolution of lung inflammation after 2 weeks of bleomycin treatment. In males, PF was associated with increased pro-inflammatory/fibrotic mediators (TGF-β and IL-1β) and decreased anti-inflammatory/anti-fibrotic factors (IFN-γ, miRNA-214-3p, miRNA-96-5p and PGE₂), particularly in the early phase of fibrosis. Pre-treatment with pirfenidone reversed fibrosis features more effectively in males, impacting anti-fibrotic miRNA-214-3p and miRNA-96-5p.

Conclusions and implications: Our data suggest that while inflammation occurs in both males and females during the early stages of PF induction, exacerbated fibrosis is observed only in males. Additionally, pirfenidone demonstrated greater activity in male mice, highlighting the need to consider potential sex-specific pharmacotherapy.

Background and purpose: LCZ696 (sacubitril/valsartan) can attenuate early cardiac remodelling of heart failure (HF), although it is less effective in severe remodelling. Surgical ventricular reconstruction (SVR) is used to treat refractory HF with large ventricular aneurysms (LVA), but residual remodelling limits the long-term survival. It is unknown whether LCZ696 can mitigate residual remodelling.

Experimental approach: Male C57BL/6 mice were subjected to myocardial infarction (MI) or sham surgery. Four weeks later, MI mice with LVA underwent SVR or a second open-chest operation, followed by randomisation to LCZ696 or vehicle. Echocardiography, histological analysis, and immunofluorescence staining were used to evaluate heart function, cardiac remodelling, and myocardial proliferation. Molecular docking, RNA pull-down, and RNA protein immunoprecipitation were used to explore downstream mechanisms. Non-targeted metabolomics and bioinformatics analysis were used to characterise metabolic changes.

Key results: LCZ696 significantly attenuated residual remodelling and further enhanced cardiomyocyte proliferation in SVR mice, but not MI mice, as evidenced by positive staining of Ki-67, phospho-histone H3, and Aurora B in the plication zone. LCZ696 increased circMap4k2 expression in SVR hearts. Silencing of circMap4k2 inhibited the efficacy of LCZ696 on improving SVR residual remodelling and cardiac proliferation, whereas overexpression of circMap4k2 promoted it. Mechanistically, circMap4k2 bound to LIN28 homologue A (LIN28A), elevating pyruvate dehydrogenase kinase 1 (PDK1) expression, thereby promoting glycolysis and reducing residual remodelling. LCZ696 reprogrammes cardiac metabolism after SVR, with 195 metabolites up-regulated and 99 down-regulated.

Conclusion and implications: LCZ696 induces glycolysis, promotes myocardial repair, and alleviates residual remodelling of SVR by targeting the circMap4k2/LIN28A/PDK1 pathway.

Chronic visceral pain imposes a major clinical challenge in gastroenterology and beyond, profoundly impacting patients' quality of life. However, limited understanding of its complex, multifaceted pathophysiology, encompassing both peripheral and central mechanisms, continues to impede the development of effective management strategies. This underscores the need for novel, targeted therapeutic approaches. Current treatment in gastroenterology often relies on conventional analgesics, including opioids, which are associated with adverse effects and limited long-term efficacy. As a result, alternative pharmacological options need to be explored. Neuromodulators, such as tricyclic antidepressants and gabapentinoids, have demonstrated therapeutic benefit, particularly in the context of central sensitization. Advances in the understanding of molecular mediators, including neurokinins, have prompted the development of receptor-targeted therapies. Nonetheless, clinical evidence remains limited and warrants further investigation. In parallel, non-pharmacological strategies, including neurostimulation and psychotherapy, are being explored. Collectively, these emerging approaches underscore the need for a mechanism-based, multimodal treatment paradigm.

Background and purpose: To investigate the basal release of 6-nitrodopamine (6-ND) from human isolated ureter and the role of this novel catecholamine in the ureter contractility.

Experimental approach: Ureters from 67 brain-dead organ donors (40 males and 27 females) were used during kidney transplantation procedures. After retrieval, a 2-cm distal ureter segment was isolated and incubated in Krebs-Henseleit solution at 37°C with continuous oxygenation. Basal 6-ND release was measured using liquid chromatography-tandem mass spectrometry. Studies were performed on 5-mm ureter rings mounted in tissue baths with isometric tension recorded via PowerLab system. Tyrosine hydroxylase (TH), S100, Pgp9.5 and eNOS expression were analysed using immunohistochemistry and fluorescence in situ hybridization (FISH).

Key results: The basal release of 6-ND was significantly reduced in epithelium-denuded compared with intact-epithelium samples. 6-ND induced concentration-dependent contractions of human ureter rings (pEC₅₀ 5.3 ± 0.2). In addition, 6-ND at 10 and 100 nM significantly potentiated contractions induced by noradrenaline and at 1 and 10 nM by adrenaline. TH was detected in epithelial cells of all human ureter samples (n = 5), with moderate to strong positivity. TH expression was confirmed by FISH. S100 and Pgp9.5 immunostaining revealed distinct patterns of nerve fibres in the tunica media and adventitia, while eNOS and TH were both expressed in the mucosal epithelium, with eNOS mainly at the surface and TH towards the basal layer.

Conclusions and implications: The finding that 6-ND is released by human ureter and modulates ureter smooth muscle contractility offers a novel insight on ureteral peristalsis mechanisms.

Background and purpose: Opioids targeting the μ opioid receptor remain largely ineffective in neuropathic pain conditions, emphasizing the need for novel therapeutic strategies. MP135 was reported to reduce thermal nociception in naive animals by activating μ-δ opioid receptor heteromers. In this study, we compared its pharmacological profile and antinociceptive properties in naive and neuropathic conditions to those of the μ-δ biased agonist CYM51010 and the μ opioid agonist morphine.

Experimental approach: Ligand affinity and activation of the G protein and β-arrestin pathways were determined using opioid receptors in their native environment. The impact of acute administration on thermal and mechanical nociceptive thresholds was evaluated in naive male and female mice. The impact on mechanical threshold and respiratory depression was also evaluated in mice with sciatic nerve injury. Pharmacological selectivity was established using μ or δ opioid receptor knock-out mice.

Key results: The three drugs showed similar binding profile and activation of G protein-dependent pathways. However, only MP135 and CYM51010 activated the β-arrestin pathway. In naive female mice, the drugs induced shorter thermal antinociception together with reduced maximal efficacy for morphine and MP135. In neuropathic conditions, morphine and MP135 were respectively poorly effective or ineffective whereas CYM51010 increased the mechanical threshold. The three drugs induced respiratory depression.

Conclusion and implications: The antinociceptive effect was receptor selective and affected by sex and neuropathic condition. This was unexpected based on the drug ex vivo pharmacological profiles and emphasizes the shortcomings of cell-based approaches to reliably predict behavioural responses.

Background and purpose: Severe dengue is characterised by systemic inflammation, cytokine storm, vascular leakage and haemorrhagic manifestations, largely driven by the host immune response to dengue virus (DENV) infection. Despite its burden, no licensed antivirals or host-directed therapies are currently available. Our group has previously identified Annexin A1 (AnxA1) as an endogenous regulator of inflammation in dengue. Treatment with the AnxA1 peptidomimetic, Ac_2-26, improved clinical outcomes in murine models of severe dengue by promoting resolution of inflammation without affecting viral control.

Experimental approach: To explore new delivery strategies, we developed a novel formulation of Ac_2-26 complexed with hydroxypropyl-β-cyclodextrin (CDX-Ac_2-26).

Key results: In DENV-2-infected A129 mice, both intraperitoneal and oral CDX-Ac_2-26 improved clinical scores and reversed thrombocytopenia. Notably, CDX-Ac_2-26 reduced mast cell degranulation, MCPT-1 plasma levels and CCL2 expression in spleen, with no effect on viral titres, indicating a host-targeted mechanism and overcoming the anti-inflammatory effects of the free peptide. Intraperitoneal administration achieved the same efficacy as oral dosing with only one-third of the dose. Importantly, the combination of CDX-Ac_2-26 with the antiviral nucleotide analogue sofosbuvir fully prevented disease and mortality in infected mice, highlighting a combinatorial effect between host-directed and antiviral therapies.

Conclusion and implications: These findings underscore the therapeutic potential of anti-inflammatory/pro-resolving strategies in severe dengue and support the development of CDX-Ac_2-26 as a novel adjunctive treatment. Combining anti-inflammatory and antiviral approaches may enhance efficacy and reduce treatment-associated toxicity, offering a promising path for clinical translation.