Acta Pharmaceutica Sinica B

Biased signaling via serotonin 5-HT₂A receptor: From structural aspects to in vitro and in vivo pharmacology

Acta Pharmaceutica Sinica B. 2025, 15(9): 4438-4455.

G protein-coupled receptors (GPCRs) represent key drug targets, with approximately 30%-40% of all medications acting on these receptors. Recent advancements have uncovered the complexity of GPCR signaling, including biased signaling, which allows selective activation of specific intracellular pathways—primarily mediated by G proteins and β-arrestins. Among aminergic GPCRs, the serotonin 5-HT₂A receptor has garnered attention for its potential to generate therapeutic effects without adverse outcomes, such as hallucinations, through biased agonism. This review delivers a comprehensive overview of 5-HT₂A receptor-biased signaling and its significance in developing safer mental health therapeutics, particularly for depression and anxiety. We provide a critical evaluation of methodologies for assessing biased signaling, spanning from traditional radioligand binding assays to advanced biosensor technologies. Furthermore, we review structural studies and computational modeling that have identified key receptor residues modulating biased signaling. We also highlight novel biased ligands with selective pathway activation, presenting a promising avenue for developing targeted antidepressant therapies without psychedelic effects. Additionally, we explore the 5-HT₂A receptor's role in memory processes and stress response regulation. Ultimately, advancing our understanding of 5-HT₂A receptor-biased signaling could drive the development of next-generation GPCR-targeted therapies, maximizing therapeutic efficacy while minimizing side effects in psychiatric treatment.

Yeast-two-hybrid based high-throughput screening to discover SARS-CoV-2 fusion inhibitors by targeting the HR1/HR2 interaction

Acta Pharmaceutica Sinica B. 2025, 15(9): 4829-4843.

The continuous emergence of SARS-CoV-2 variants as well as other potential future coronavirus has challenged the effectiveness of current COVID-19 vaccines. Therefore, there remains a need for alternative antivirals that target processes less susceptible to mutations, such as the formation of six-helix bundle (6-HB) during the viral fusion step of host cell entry. In this study, a novel high-throughput screening (HTS) assay employing a yeast-two-hybrid (Y2H) system was established to identify inhibitors of HR1/HR2 interaction. The compound IMB-9C, which achieved single-digit micromolar inhibition of SARS-CoV-2 and its Omicron variants with low cytotoxicity, was selected. IMB-9C effectively blocks the HR1/HR2 interaction in vitro and inhibits SARS-CoV-2-S-mediated cell-cell fusion. It binds to both HR1 and HR2 through non-covalent interaction and influences the secondary structure of HR1/HR2 complex. In addition, virtual docking and site-mutagenesis results suggest that amino acid residues A930, I931, K933, T941, and L945 are critical for IMB-9C binding to HR1. Collectively, in this study, we have developed a novel screening method for HR1/HR2 interaction inhibitors and identified IMB-9C as a potential antiviral small molecule against COVID-19 and its variants.

Pleiotropic prodrugs for both symptomatic and disease-modifying treatment of Alzheimer's disease

Acta Pharmaceutica Sinica B. 2025, 15(9): 4807-4828.

The inherent complexity of Alzheimer's disease (AD) and failed clinical trials have spiked the interest in multifunctional ligands that target at least two key disease-associated macromolecules in AD pathology. Here we present a focused series of pleiotropic N-carbamoylazole prodrugs with dual mechanism of action. Pseudo-irreversible inhibition of the first therapeutic target, human butyrylcholinesterase (hBChE), enhances cholinergic transmission, and thereby provides symptomatic treatment, same as the standard therapeutics in use for AD. Simultaneously, this step also functions as a metabolic activation that liberates a nanomolar selective α₂-adrenergic antagonist atipamezole, which blocks pathological amyloid β (Aβ)-induced and noradrenaline-dependent activation of GSK3β that ultimately leads to hyperphosphorylation of tau, thus achieving a disease-modifying effect. Lead compound 8 demonstrated long-term pseudo-irreversible hBChE inhibition, metabolic activation in human plasma, blood-brain barrier permeability, and p.o. bioavailability in mice. Multi-day in vivo treatment with 8 in an Aβ-induced AD murine model revealed a significant alleviation of cognitive deficit that was comparable to rivastigmine, the current drug of choice for AD therapy. Furthermore, decreased GSK3β activation and lowered tau phosphorylation were observed in APP/PS1 mice. This surpasses the symptomatic-only treatment with cholinesterase inhibitors, as it directly blocks an essential pathological cascade in AD. Therefore, these multifunctional α₂-adrenergic antagonists-butyrylcholinesterase inhibitors, exemplified by lead compound 8, present an innovative, small molecule-based, disease-modifying approach to treatment of AD.

Understanding the complexity of tumor-associated macrophages: Druggable and therapeutic insights

Acta Pharmaceutica Sinica B. 2025, 15(9): 4456-4475.

Macrophages are immune cells capable of exerting both pro-tumor and anti-tumor effects. Tumor-associated macrophages (TAMs) comprise a heterogeneous group of macrophages originating from monocytes and resident tissue macrophages. Their phenotypes and functions vary depending on factors such as tumor type, location, and stage. TAMs can promote tumor growth, angiogenesis, metastasis, immunosuppression, and drug resistance, or they can facilitate antigen presentation and immune activation, thereby contributing to tumor elimination. As such, TAMs are potential targets for cancer therapy, and various pharmacological strategies and clinic-approved drugs have been suggested to modulate their activity, recruitment, and depletion. However, the complexity and diversity of TAMs present significant challenges to understanding their roles and designing effective drug interventions. This review summarizes the current knowledge of TAMs, and drug development for TAMs as anti-tumor therapy targets, emphasizing the importance of single-cell omics technologies for characterizing TAM heterogeneity and identifying therapeutic opportunities. Additionally, it presents the latest clinical trials focused on TAM-targeted therapies and drugs. Collectively, this review discusses the therapeutic opportunities and challenges of TAM-targeted drug therapies and offers future perspectives and directions for advancing our understanding and manipulation of TAMs in drug development.

Ischemic stroke and intervention strategies based on the timeline of stroke progression: Review and prospects

Acta Pharmaceutica Sinica B. 2025, 15(9): 4543-4581.

Ischemic stroke (IS), a leading cause of morbidity and mortality worldwide, primarily results from blood clot formation in cerebral vessels, leading to vessel occlusion, reduced cerebral blood flow, and subsequent tissue ischemia. While thrombolytic therapies and mechanical thrombectomy remain cornerstone treatments for restoring blood flow, their clinical efficacy is significantly limited by the narrow therapeutic window, which underscores the critical need for novel, safe, and effective therapeutic strategies. In this review, we present an intensive analysis of four pathophysiological stages of IS progression and their intervention targets, and evaluate both established and emerging therapeutic strategies with the molecular mechanisms underpinning these methods, aiming to enhance the understanding of IS intervention. Additionally, we discuss current challenges in IS therapy, emphasizing the importance of timely, stage-specific approaches to optimize therapeutic outcomes. Finally, we highlight some promising research directions and innovations to advance IS field.

Immunoregulatory mechanisms in the aging microenvironment: Targeting the senescence-associated secretory phenotype for cancer immunotherapy

Acta Pharmaceutica Sinica B. 2025, 15(9): 4476-4496.

The aging microenvironment, as a key driver of tumorigenesis and progression, plays a critical role in tumor immune regulation through one of its core features—the senescence-associated secretory phenotype (SASP). SASP consists of a variety of interleukins, chemokines, proteases, and growth factors. It initially induces surrounding cells to enter a state of senescence through paracrine mechanisms, thereby creating a sustained inflammatory stimulus and signal amplification effect within the tissue microenvironment. Furthermore, these secreted factors activate key signaling pathways such as NF-κB, cGAS-STING, and mTOR, which regulate the expression of immune-related molecules (such as PD-L1) and promote the recruitment of immunosuppressive cells, including regulatory T cells and myeloid-derived suppressor cells. This process ultimately contributes to the formation of an immunosuppressive tumor microenvironment. Furthermore, the article explores potential anti-tumor immunotherapy strategies targeting SASP and its associated molecular mechanisms, including approaches to inhibit SASP secretion or eliminate senescent cells. Although these strategies have shown promise in certain tumor models, the high heterogeneity among tumor types may result in varied responses to SASP-targeted therapies. This highlights the need for further research into adaptive stratification and personalized treatment approaches. Targeting immune regulatory mechanisms in the aging microenvironment—particularly SASP—holds great potential for advancing future anti-tumor therapies.

The role of SARS-CoV-2 main protease in innate immune regulation: From molecular mechanisms to therapeutic implications

Acta Pharmaceutica Sinica B. 2025, 15(9): 4497-4510.

The main protease (Mpro) of SARS-CoV-2 plays a pivotal role in viral replication and immune evasion. Accumulating evidence highlights its significant role in suppressing innate immunity. In this review, we provide a comprehensive overview of how Mpro modulates host innate immune responses, including its interference with retinoic acid-inducible gene I (RIG-I)-like receptor (RLR) and cyclic GMP-AMP synthase (cGAS)-stimulator of interferon gene (STING) signaling pathways, inhibition of interferon production, and disruption of inflammasome activities. As a protease, Mpro cleaves a variety of host proteins to attenuate antiviral innate immunity, a process dependent on its catalytic dyad (Cys145-His41), which is crucial for its proteolytic activity. Meanwhile, Mpro also exerts innate immune regulatory functions in a protease-independent manner. Notably, inhibitors targeting Mpro have demonstrated efficacy in restoring immune functions and suppressing viral replication, offering potential therapeutic strategies against SARS-CoV-2 infection.

Astrocyte FGF7/FGFR2 autocrine signaling mediates neuroinflammation and promotes MPTP-induced degeneration of dopaminergic neurons

Acta Pharmaceutica Sinica B. 2025, 15(9): 4730-4750.

Reactive astrocytes, which exhibit a correlation with the degeneration of dopaminergic neurons, are present in a considerable number during the progression of Parkinson's disease (PD). However, the underlying factors shaping astrocyte reactivity and neuroinflammation in PD remain inadequately elucidated. Here, we demonstrate that fibroblast growth factor 7 (FGF7)/FGF receptor 2 (FGFR2) autocrine signaling intensifies astrocyte reactivity and inflammation. Genetic deletion of Arrb2, β-Arrestin2 encoding gene, led to escalated astrocyte reactivity in MPTP-treated mice, which was further substantiated in astrocyte-specific Arrb2 knockdown mice. RNA sequencing profiling of Arrb2 knockout astrocytes identified Fgf7 as a critical effector of astrocyte reactivity. Subsequently, conditional knockdown of Fgf7 and its receptor Fgfr2 in astrocytes elicited advantageous effects for MPTP-treated mice by restraining the inflammatory phenotypic transition of reactive astrocytes. Furthermore, deletion of astrocytic Fgf7 mitigated MPTP-induced pathology in Arrb2 knockout mice. Mechanistically, STAT1 was distinguished as the transcription factor suppressing Fgf7 expression, while β-Arrestin2 counteracted the proteasomal degradation of STAT1 by binding to RNF220, an E3 ubiquitin ligase for STAT1. More importantly, selectively engaging dopamine D2 receptor (Drd2)/β-Arrestin2-biased signaling using the agonist UNC9995 exhibited therapeutic potential in MPTP-treated mice via moderation of astrocytic FGF7 production, thereby restoring balance in astrocyte reactivity. Collectively, our study bridges a crucial knowledge gap by elucidating the novel functions of FGF family members within the central nervous system, particularly within the context of PD. The autocrine signaling of FGF7/FGFR2 represents a novel mechanism and a potential druggable target for modulating astrocyte-derived inflammation.

Natural vaccine adjuvants from traditional Chinese medicines: Mechanisms to applications

Xiaoyuan Fan, Fengxiang Liu, Fei Sun, Yiyang Wang, Wenwen Shen, Shujun Wang, Jin Sun, Kaiyuan Wang

Acta Pharmaceutica Sinica B. 2025, 15(9): 4644-4672.

With the rapid advancement of vaccines, the research and application of vaccine adjuvants have garnered significant attention. Despite the development of numerous vaccine adjuvants, their applications in human vaccines remain limited due to either insufficient efficacy or severe side effects. Consequently, there is growing interest in developing bioactive compounds derived from traditional Chinese medicines (TCMs) as vaccine adjuvants, owing to their natural biocompatibility, diversity, and safety. Here, we systematically review the current application status and potential value of TCM-based bioactive compounds in vaccine adjuvants. Firstly, we elaborate on the types and characteristics of active ingredients, such as polysaccharides, saponins, flavonoids, acids, and alkaloids. The mechanisms by which these compounds function as vaccine adjuvants are then discussed, including their roles in enhancing humoral immunity, cellular immunity, and relieving the immune suppression in the microenvironment. Additionally, we summarize the current strategies for structural modification and platform optimization to adapt to different application scenarios. Finally, we offer insights into the future development directions for these potential adjuvants, highlighting research priorities, technical approaches, and application prospects. In conclusion, natural vaccine adjuvants derived from TCMs present broad application prospects and hold promise for future vaccine development.

AI-powered model for accurate prediction of MCI-to-AD progression

Acta Pharmaceutica Sinica B. 2025, 15(9): 4427-4437.

Alzheimer's disease (AD) remains a formidable challenge in modern healthcare, necessitating innovative approaches for its early detection and intervention. This study aimed to enhance the identification of individuals with mild cognitive impairment (MCI) at risk of developing AD. Leveraging advances in computational power and the extensive availability of healthcare data, we explored the potential of deep learning models for early prediction using medical claims data. We employed a bidirectional gated recurrent unit (BiGRU) deep learning model for predictive modeling of MCI progression across various prediction intervals, extending up to five years post-initial MCI diagnosis. The performance of the BiGRU model was rigorously compared with several machine-learning model baselines to evaluate its efficacy. Using a robust cross-validation methodology, the BiGRU emerged as the top-performing model, achieving an Area Under the Receiver Operating Characteristic Curve (AUC-ROC) of 0.833 (95% CI: 0.822, 0.843), an Area Under the Precision-Recall Curve (AUC-PR) of 0.856 (95% CI: 0.845, 0.867), and an F1-Score of 0.71 (95% CI: 0.694, 0.724) for a five-year prediction interval. The results indicate that BiGRU, utilizing longitudinal claims data, reliably predicts MCI-to-AD progression over a lengthy interval following the initial MCI diagnosis, offering clinicians a valuable tool for targeted risk identification and stratification.