Development of an Orally Active Small-Molecule Inhibitor of Receptor Activator of Nuclear Factor-κB Ligand

Targeting Osteoblast-Osteoclast Cross-Talk Bone Homeostasis Repair Microcarriers Promotes Intervertebral Fusion in Osteoporotic Rats

Balancing osteoblast-osteoclast (OB-OC) cross-talk is crucial for restoring bone tissue structure and function. Current clinical drugs targeting either osteogenesis or osteoclastogenesis fail to effectively regulate cross-talk, impeding efficient bone repair in osteoporosis patients. Ubiquitin-specific protease 26 (USP26) is shown to coordinate OB-OC cross-talk by independently regulating β-catenin and Iκb-α. However, effective drugs for activating USP26 are still lacking. Here, they constructed bone homeostasis repair microcarriers (BHRC) that encapsulate Usp26 mRNA-loaded lipid nanoparticles (mRNA@LNP) within MMPs-responsive GelMA hydrogel microspheres. These microcarriers target the osteoporotic microenvironment and regulate OB-OC cross-talk, thereby facilitating intervertebral fusion in osteoporotic rats. Results demonstrate that mRNA@LNP exhibits uniform particle size and high transfection efficiency, while GelMA hydrogel microspheres possess excellent biocompatibility and MMP responsiveness, providing favorable cell survival space and controllable release of mRNA@LNP. The released LNP upregulates USP26 protein expression, effectively promoting osteogenesis while suppressing osteoclast formation. In vivo experiments show that injecting BHRC into the defect site of intervertebral discs in osteoporotic rats significantly promotes tail vertebrae fusion by responding to the microenvironment and regulating cell-to-cell cross-talk. Thus, the BHRC holds great potential in regulating osteoporotic homeostasis, particularly in challenging bone defects such as intervertebral fusion in osteoporotic environments.

Jaw osteoporosis: Challenges to oral health and emerging perspectives of treatment

Osteoporosis is a prevalent bone metabolic disease that poses a significant challenge to global human health. Jaw osteoporosis, characterized by microstructural damage of the jaw resulting from various factors, is one of the common manifestations of this condition. Recent studies have demonstrated that jaw osteoporosis has multifaceted effects on oral health and can negatively impact conditions such as periodontitis, oral implantation, orthodontic treatment, and wound healing. However, there are still some limitations in the conventional treatment of osteoporosis. For instance, while bisphosphonates can enhance bone quality, they may also lead to osteonecrosis of the jaw, which poses a potential safety hazard in oral diagnosis and treatment. In recent years, considerable attention has been focused on improving the pathological condition of jaw osteoporosis. Treatment strategies such as gut microbial regulation, extracellular vesicles, molecular targeted therapy, herbal medicine, mechanical stimulation are expected to enhance efficacy and minimize adverse reactions. Therefore, understanding these effects and exploring novel treatments for jaw osteoporosis may provide new insights for oral health maintenance and disease treatment. This article reviews the impact of jaw osteoporosis on oral health and describes the limitations associated with current methods. It also discusses emerging perspectives on treatment, offering a comprehensive overview of the challenges and future directions in managing jaw osteoporosis.

Optimization and biological evaluation of l-DOPA derivatives as potent influenza PAN endonuclease inhibitors with multi-site binding characteristics

Emerging and potential influenza pandemics still are an enormous worldwide public health challenge. The PAN endonuclease has been proved to be a promising target for anti-influenza drug design. Here, we report the discovery and optimization of potent Y-shaped PAN inhibitors featuring multi-site binding characteristics with l-DOPA as a starting point. We systematically modified the hit 1 bearing two-binding characteristics based on structure-based rational design combined with multisite binding and conformational constraint strategies, generating four families of l-DOPA derivatives for SARs analysis. Among these substances, N, 3-di-substituted 1, 2, 3, 4-tetrahydroisoquinoline derivative T-31 displayed superior properties as a lead PAN endonuclease inhibitor and antiviral agent. The lead T-31 inhibited PAN endonuclease activity with an IC50 value of 0.15 μM and showed broad and submicromolar anti-influenza potency in cell-based assays. More importantly, T-31 could simultaneously target both influenza HA and the RdRp complex, thus interfering with virus entry into host cells and viral replication. This study offers a set of novel PAN endonuclease inhibitors with multi-site binding characteristics starting from the l-DOPA skeleton.

Structure-Based Discovery of Receptor Activator of Nuclear Factor-κB Ligand (RANKL)-Induced Osteoclastogenesis Inhibitors

Receptor activator of nuclear factor-κB ligand (RANKL) has been actively pursued as a therapeutic target for osteoporosis, given that RANKL is the master mediator of bone resorption as it promotes osteoclast differentiation, activity and survival. We employed a structure-based virtual screening approach comprising two stages of experimental evaluation and identified 11 commercially available compounds that displayed dose-dependent inhibition of osteoclastogenesis. Their inhibitory effects were quantified through TRAP activity at the low micromolar range (IC₅₀ < 5 μΜ), but more importantly, 3 compounds displayed very low toxicity (LC₅₀ > 100 μΜ). We also assessed the potential of an N-(1-aryl-1H-indol-5-yl)aryl-sulfonamide scaffold that was based on the structure of a hit compound, through synthesis of 30 derivatives. Their evaluation revealed 4 additional hits that inhibited osteoclastogenesis at low micromolar concentrations; however, cellular toxicity concerns preclude their further development. Taken together with the structure-activity relationships provided by the hit compounds, our study revealed potent inhibitors of RANKL-induced osteoclastogenesis of high therapeutic index, which bear diverse scaffolds that can be employed in hit-to-lead optimization for the development of therapeutics against osteolytic diseases.

Mechanistic advances in osteoporosis and anti-osteoporosis therapies

Osteoporosis is a type of bone loss disease characterized by a reduction in bone mass and microarchitectural deterioration of bone tissue. With the intensification of global aging, this disease is now regarded as one of the major public health problems that often leads to unbearable pain, risk of bone fractures, and even death, causing an enormous burden at both the human and socioeconomic layers. Classic anti-osteoporosis pharmacological options include anti-resorptive and anabolic agents, whose ability to improve bone mineral density and resist bone fracture is being gradually confirmed. However, long-term or high-frequency use of these drugs may bring some side effects and adverse reactions. Therefore, an increasing number of studies are devoted to finding new pathogenesis or potential therapeutic targets of osteoporosis, and it is of great importance to comprehensively recognize osteoporosis and develop viable and efficient therapeutic approaches. In this study, we systematically reviewed literatures and clinical evidences to both mechanistically and clinically demonstrate the state-of-art advances in osteoporosis. This work will endow readers with the mechanistical advances and clinical knowledge of osteoporosis and furthermore present the most updated anti-osteoporosis therapies.

Harnessing the cyclization strategy for new drug discovery

The design of new ligands with high affinity and specificity against the targets of interest has been a central focus in drug discovery. As one of the most commonly used methods in drug discovery, the cyclization represents a feasible strategy to identify new lead compounds by increasing structural novelty, scaffold diversity and complexity. Such strategy could also be potentially used for the follow-on drug discovery without patent infringement. In recent years, the cyclization strategy has witnessed great success in the discovery of new lead compounds against different targets for treating various diseases. Herein, we first briefly summarize the use of the cyclization strategy in the discovery of new small-molecule lead compounds, including the proteolysis targeting chimeras (PROTAC) molecules. Particularly, we focus on four main strategies including fused ring cyclization, chain cyclization, spirocyclization and macrocyclization and highlight the use of the cyclization strategy in lead generation. Finally, the challenges including the synthetic intractability, relatively poor pharmacokinetics (PK) profiles and the absence of the structural information for rational structure-based cyclization are also briefly discussed. We hope this review, not exhaustive, could provide a timely overview on the cyclization strategy for the discovery of new lead compounds.