Bayesian metamodeling of complex biological systems across varying representations.

Comprehensive modeling of a whole cell requires an integration of vast amounts of information on various aspects of the cell and its parts. To divide and conquer this task, we introduce Bayesian metamodeling, a general approach to modeling complex systems by integrating a collection of heterogeneous input models. Each input model can in principle be based on any type of data and can describe a different aspect of the modeled system using any mathematical representation, scale, and level of granularity. These input models are 1) converted to a standardized statistical representation relying on probabilistic graphical models, 2) coupled by modeling their mutual relations with the physical world, and 3) finally harmonized with respect to each other. To illustrate Bayesian metamodeling, we provide a proof-of-principle metamodel of glucose-stimulated insulin secretion by human pancreatic ß-cells. The input models include a coarse-grained spatiotemporal simulation of insulin vesicle trafficking, docking, and exocytosis; a molecular network model of glucose-stimulated insulin secretion signaling; a network model of insulin metabolism; a structural model of glucagon-like peptide-1 receptor activation; a linear model of a pancreatic cell population; and ordinary differential equations for systemic postprandial insulin response. Metamodeling benefits from decentralized computing, while often producing a more accurate, precise, and complete model that contextualizes input models as well as resolves conflicting information. We anticipate Bayesian metamodeling will facilitate collaborative science by providing a framework for sharing expertise, resources, data, and models, as exemplified by the Pancreatic ß-Cell Consortium.

DrugSpaceX: a large screenable and synthetically tractable database extending drug space.

One of the most prominent topics in drug discovery is efficient exploration of the vast drug-like chemical space to find synthesizable and novel chemical structures with desired biological properties. To address this challenge, we created the DrugSpaceX (https://drugspacex.simm.ac.cn/) database based on expert-defined transformations of approved drug molecules. The current version of DrugSpaceX contains >100 million transformed chemical products for virtual screening, with outstanding characteristics in terms of structural novelty, diversity and large three-dimensional chemical space coverage. To illustrate its practical application in drug discovery, we used a case study of discoidin domain receptor 1 (DDR1), a kinase target implicated in fibrosis and other diseases, to show DrugSpaceX performing a quick search of initial hit compounds. Additionally, for ligand identification and optimization purposes, DrugSpaceX also provides several subsets for download, including a 10% diversity subset, an extended drug-like subset, a drug-like subset, a lead-like subset, and a fragment-like subset. In addition to chemical properties and transformation instructions, DrugSpaceX can locate the position of transformation, which will enable medicinal chemists to easily integrate strategy planning and protection design.

[Serum metabolomics study of Psoraleae Fructus in improving learning and memory ability of APP/PS1 mice].

This study aimed to investigate the mechanism of Psoraleae Fructus in improving the learning and memory ability of APP/PS1 mice by serum metabolomics, screen the differential metabolites of Psoraleae Fructus on APP/PS1 mice, and reveal its influence on the metabolic pathway of APP/PS1 mice. Thirty 3-month-old APP/PS1 mice were randomly divided into a model group and a Psoraleae Fructus extract group, and another 15 C57BL/6 mice of the same age were assigned to the blank group. The learning and memory ability of mice was evaluated by the Morris water maze and novel object recognition tests, and metabolomics was used to analyze the metabolites in mouse serum. The results of the Morris water maze test showed that Psoraleae Fructus shortened the escape latency of APP/PS1 mice(P<0.01), and increased the number of platform crossing and residence time in the target quadrant(P<0.01). The results of the novel object recognition test showed that Psoraleae Fructus could improve the novel object recognition index of APP/PS1 mice(P<0.01). Eighteen differential metabolites in serum were screened out by metabolomics, among which the levels of arachidonic acid, tryptophan, and glycerophospholipid decreased after drug administration, while the levels of glutamyltyrosine increased after drug administration. The metabolic pathways involved included arachidonic acid metabolism, glycerophospholipid metabolism, tryptophan metabolism, linoleic acid metabolism, α-linolenic acid metabolism, and glycerolipid metabolism. Therefore, Psoraleae Fructus can improve the learning and memory ability of APP/PS1 mice, and its mechanism may be related to the effects in promoting energy metabolism, reducing oxidative damage, protecting central nervous system, reducing neuroinflammation, and reducing Aß deposition. This study is expected to provide references for Psoraleae Fructus in the treatment of Alzheimer's disease(AD) and further explain the mechanism of Psoraleae Fructus in the treatment of AD.

[Mechanism of albiflorin in improvement of Alzheimer's disease based on network pharmacology and in vitro experiments].

This study aimed to explore the mechanism of albiflorin in the treatment of Alzheimer's disease(AD) based on network pharmacology, molecular docking, and in vitro experiments. Network pharmacology was used to predict the potential targets and pathways of albiflorin against AD, and molecular docking technology was used to verify the binding affinity of albiflorin to key target proteins. Finally, the AD cell model was induced by Aß_(25-35) in rat pheochromocytoma(PC12) cells and intervened by albiflorin to validate core targets and pathways. The results of network pharmacological analysis showed that albiflorin acted on key targets such as mitogen-activated protein kinase-1(MAPK1 or ERK2), albumin(ALB), epidermal growth factor receptor(EGFR), caspase-3(CASP3), and sodium-dependent serotonin transporter(SLC6A4), and signaling pathways such as MAPK, cAMP, and cGMP-PKG. The results of molecular docking showed that albiflorin had strong binding affinity to MAPK1(ERK2). In vitro experiments showed that compared with the blank group, the model group showed decreased cell viability, decreased expression level of B-cell lymphoma 2(Bcl-2), increased Bcl-2-associated X protein(Bax), and reduced phosphorylation level of extracellular signal-regulated kinase 1/2(ERK1/2) and the relative expression ratio of p-ERK1/2 to ERK1/2. Compared with the model group, the albiflorin group showed potentiated cell viability, up-regulated expression of Bcl-2, down-regulated Bax, and increased phosphorylation level of ERK1/2 and the relative expression ratio of p-ERK1/2 to ERK1/2. These results suggest that the mechanism of albiflorin against AD may be related to its activation of the MAPK/ERK signaling pathway and its inhibition of neuronal apoptosis.

Integrative modeling of the cell.

A whole-cell model represents certain aspects of the cell structure and/or function. Due to the high complexity of the cell, an integrative modeling approach is often taken to utilize all available information including experimental data, prior knowledge and prior models. In this review, we summarize an emerging workflow of whole-cell modeling into five steps: (i) gather information; (ii) represent the modeled system into modules; (iii) translate input information into scoring function; (iv) sample the whole-cell model; (v) validate and interpret the model. In particular, we propose the integrative modeling of the cell by combining available (whole-cell) models to maximize the accuracy, precision, and completeness. In addition, we list quantitative predictions of various aspects of cell biology from existing whole-cell models. Moreover, we discuss the remaining challenges and future directions, and highlight the opportunity to establish an integrative spatiotemporal multi-scale whole-cell model based on a community approach.

KinomeX: a web application for predicting kinome-wide polypharmacology effect of small molecules.

MOTIVATION: The large-scale kinome-wide virtual profiling for small molecules is a daunting task by experimental and traditional in silico drug design approaches. Recent advances in deep learning algorithms have brought about new opportunities in promoting this process. RESULTS: KinomeX is an online platform to predict kinome-wide polypharmacology effect of small molecules based solely on their chemical structures. The prediction is made by a multi-task deep neural network model trained with over 140 000 bioactivity data points for 391 kinases. Extensive computational and experimental validations have been performed. Overall, KinomeX enables users to create a comprehensive kinome interaction network for designing novel chemical modulators, and is of practical value on exploring the previously less studied or untargeted kinases. AVAILABILITY AND IMPLEMENTATION: KinomeX is available at: https://kinome.dddc.ac.cn. SUPPLEMENTARY INFORMATION: Supplementary data are available at Bioinformatics online.

Diterpenoids from the Root Bark of Pinus massoniana and Evaluation of Their Phosphodiesterase Type 4D Inhibitory Activity.

Thirty-two diterpenoids were obtained from the root bark of Pinus massoniana, and, among them, five compounds (pinmassins A-E) were identified as undescribed analogues. Spectroscopic methods, X-ray single-crystal diffraction analysis, and ECD calculations were applied to establish the structure of the new isolates. Pinmassin D (4) and abieta-8,11,13,15-tetraen-18-oic acid (23) showed moderate phosphodiesterase type 4D (PDE4D) inhibitory effects with IC50 values of 2.8 ± 0.18 and 3.3 ± 0.50 µM, respectively, and their binding modes were investigated by a molecular docking study.

Hydrolytic Metabolism of Cyanopyrrolidine DPP-4 Inhibitors Mediated by Dipeptidyl Peptidases.

Nitrile group biotransformation is an unusual or minor metabolic pathway for most nitrile-containing drugs. However, for some cyanopyrrolidine dipeptidyl peptidase 4 (DPP-4) inhibitors (vildagliptin, anagliptin, and besigliptin, but not saxagliptin), the conversion of nitrile group into carboxylic acid is their major metabolic pathway in vivo. DPP-4 was reported to be partly involved in the metabolism. In our pilot study, it was also observed that saxagliptin, a DPP-4 specific inhibitor, decreased the plasma exposures of besigliptin carboxylic acid in rats by only 20%. Therefore, it is speculated that some other enzymes may participate in nitrile group hydrolysis. After incubating gliptins with the cytosol, microsomes, and mitochondria of liver and kidney, carboxylic acid metabolites could all be formed. In recombinant DPP family such as DPP-4, DPP-2, DPP-8, DPP-9, and fibroblast activation protein-α, more hydrolytic metabolites were found. Among them, DPP-2 had the highest hydrolytic capacity besides DPP-4, and the DPP-4 inhibitor saxagliptin and DPP-2 inhibitor AX8819 can both inhibit the hydrolysis of gliptins. Western blot results showed that DPP-2 and DPP-4 existed in the aforementioned subcellular organelles at varying amounts. In rats, AX8819 decreased the plasma exposures of besigliptin carboxylic acid by 40%. The amide intermediates of gliptins were detected in vivo and in vitro. When the amide derivatives of gliptins were incubated with DPP-4, they were completely hydrolyzed at a rate far more than that from the parent drug, including saxagliptin-amide. Therefore, it was proposed that gliptins, except saxagliptin, were initially hydrolyzed to their amides by DPPs, which was the rate-limiting step in generating the carboxylic end product.

Computational chemical biology and drug design: Facilitating protein structure, function, and modulation studies.

Over the past quarter of a century, there has been rapid development in structural biology, which now can provide solid evidence for understanding the functions of proteins. Concurrently, computational approaches with particular relevance to the chemical biology and drug design (CBDD) field have also incrementally and steadily improved. Today, these methods help elucidate detailed working mechanisms and accelerate the discovery of new chemical modulators of proteins. In recent years, integrating computational simulations and predictions with experimental validation has allowed for more effective explorations of the structure, function and modulation of important therapeutic targets. In this review, we summarize the main advancements in computational methodology development, which are then illustrated by several successful applications in CBDD. Finally, we conclude with a discussion of the current major challenges and future directions in the field.

In Vivo Microdialysis for Dynamic Monitoring of the Effectiveness of Nano-liposomes as Vehicles for Topical Psoralen Application.

In this study, the skin permeation of liposomes containing psoralen was investigated by in vivo skin microdialysis. Psoralen-loaded nano-sized liposomes were prepared with a mean size of 117.5 nm and a polydispersity index of 0.21, indicating the uniform dispersion of phosphatidylcholine vesicles in the liposomal solution. Based on in vivo microdialysis experiments, the drug concentration in local deep skin of rat increased rapidly and reached a peak concentration (Cmax) of 319.35±23.72 µg/mL at 180 min, and decreased slowly thereafter. The local area under the concentration-time curve (AUC)0-t was 3.81-fold higher than the compared aqueous suspension. The in vivo systemic pharmacokinetics were in agreement with the microdialysis results, in view of the Cmax and AUC0-t from liposomal group were both significantly higher (p<0.05) than the compared group. Liposome-associated transdermal psoralen delivery was significantly more effective than delivery via an aqueous suspension. The enhanced skin permeability may be associated with improved skin hydration, lipid exchange and fusion with the stratum corneum (SC), and changes in SC structure, promoting drug permeation into deep skin. After 10 h of treatment with the perfusate, the microstructure of the microdialysis probe exhibited no obvious differences with control probes. The skin surface and the tissue around the probe showed no swelling or inflammation. These findings indicated that liposomes effectively enhanced the skin deposition of psoralen and showed good biocompatibility with skin tissues; additionally, ethanol at a low concentration in ringer's solution is an alternative perfusate for in vivo skin microdialysis studies.

The metabolomic study on atherosclerosis mice and its application in a traditional Chinese medicine Sishen granule.

Although an atherosclerosis (AS) model using low-density lipoprotein receptor deletion mice has been widely applied, its pathological pathway in metabolite level is still not clear. To further reveal the metabolite profile and identify the potential biomarkers in AS development, a serum metabolomic approach was developed based on reversed-phase liquid chromatography/quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS). The established metabolomic platform was also used for elucidating the therapeutic mechanism of a traditional Chinese medicine named Sishen granule (SSKL). Twenty-one potential biomarkers in AS mouse serum were identified. Through functional analysis of these biomarkers, inflammation, proliferation, dysfunction of energy metabolism and amino acid metabolism were considered the most relevant pathological changes in AS. DNA damage products were found for the first time in the metabolomic study of AS. The network established by 20 biomarkers revealed that pyruvate metabolism, citrate cycle, fatty acid metabolism and urea metabolism were seriously disturbed. This metabolomic study not only supplied a systematic view of the progression of AS but also provided a theoretical basis for the treatment of AS. This metabolomic study also demonstrated that SSKL had therapeutic effectiveness for AS through partly reversing the inflammation reaction and amino acid metabolism dysfunction. Copyright © 2015 John Wiley & Sons, Ltd.

Correction: Zhao, J., et al. Podophyllotoxin-Loaded Nanostructured Lipid Carriers for Skin Targeting: In Vitro and In Vivo Studies. Molecules 2016, 21, 1549.

The authors wish to make the following correction to their paper [1].

Podophyllotoxin-Loaded Nanostructured Lipid Carriers for Skin Targeting: In Vitro and In Vivo Studies.

Nanostructured lipid carriers (NLC) exhibit high skin targeting efficiency and good safety. They are promising vehicles for topical drug delivery. This study aims to increase the skin distribution of podophyllotoxin (POD) by incorporating it into NLCs. Two kinds of POD-loaded NLCs (POD-NLCs)-POD-NLCformulation 1 and POD-NLCformulation 2-were prepared and characterized. Their skin targeting efficiencies were compared by conducting in vitro and in vivo experiments. Obviously smaller mean particle size was observed for POD-NLCformulation 1 (106 nm) than POD-NLCformulation 2 (219 nm), whereas relatively low POD loadings (less than 0.5%) were observed for both POD-NLCformulation 1 (0.33%) and POD-NLCformulation 2 (0.49%). Significantly higher in vitro and in vivo rat skin deposit amounts of POD (p ˂ 0.01) were detected after the topical application of POD-NLCformulation 1 compared to POD-NLCformulation 2. To visualize the skin distribution behavior of hydrophobic active pharmaceutical ingredients (APIs) when NLCs were used as carriers, POD was replaced with Nile red (NR-a hydrophobic fluorescent probe), and the distribution behavior of NR-NLCformulation 1 and NR-NLCformulation 2 in rat skin in vivo was observed using confocal laser scanning microscopy (CLSM). Higher fluorescent intensity was observed in rat skin after the topical application of NR-NLCformulation 1 than NR-NLCformulation 2, suggesting that higher skin targeting efficiency might be obtained when NLCs with smaller mean particle size were used as carriers for hydrophobic APIs. This result was in accordance with those of skin distribution evaluation experiments of POD-NLCs. Skin irritation property of POD-NLCformulation 1 was investigated and no irritation was observed in intact or damaged rabbit skin, suggesting it is safe for topical use. Our results validated the safety of NLCs when applied topically. More importantly, mean particle size might be an important parameter for formulation optimization when NLCs are used as carriers for hydrophobic APIs for topical application, considering that their loading is relatively low.

Nanostructured lipid carriers for percutaneous administration of alkaloids isolated from Aconitum sinomontanum.

BACKGROUND: Lipid-based nanosystems have great potential for transdermal drug delivery. In this study, nanostructured lipid carriers (NLCs) for short-acting alkaloids lappacontine (LA) and ranaconitine (RAN) isolated from Aconitum sinomontanum (AAS) at 69.47 and 9.16% (w/w) yields, respectively, were prepared to enhance percutaneous permeation. Optimized NLC formulations were evaluated using uniform design experiments. Microstructure and in vitro/in vivo transdermal delivery characteristics of AAS-loaded NLCs and solid lipid nanoparticles (SLNs) were compared. Cellular uptake of fluorescence-labeled nanoparticles was probed using laser scanning confocal microscopy and fluorescence-activated cell sorting. Nanoparticle integrity during transdermal delivery and effects on the skin surface were also investigated. RESULTS: NLC formulations were less cytotoxic than the AAS solution in HaCaT and CCC-ESF cells. Moreover, coumarin-6-labeled NLCs showed biocompatibility with HaCaT and CCC-ESF cells, and their cellular uptake was strongly affected by cholesterol and lipid rafts. Significantly greater cumulative amounts of NLC-associated LA and RAN than SLN-associated alkaloids penetrated the rat skin in vitro. In vivo microdialysis showed higher area under the concentration-time curve (AUC)0-t for AAS-NLC-associated LA and RAN than for AAS-SLN-associated alkaloids. CONCLUSIONS: NLC formulations could be good transdermal systems for increasing biocompatibility and decreasing cytotoxicity of AAS. AAS-NLCs showed higher percutaneous permeation than the other preparations. These findings suggest that NLCs could be promising transdermal delivery vehicles for AAS.

In vivo microdialysis for the evaluation of transfersomes as a novel transdermal delivery vehicle for cinnamic acid.

In this study, cinnamic acid-loaded transfersomes were prepared and dermal microdialysis sampling was used in Sprague-Dawley rats to compare the amount of drug released into the skin using transfersomes as transdermal carriers with that released on using conventional liposomes. The formulation of cinnamic acid-loaded transfersomes was optimized by a uniform design through in vitro transdermal permeation studies. Hydration time was confirmed as a significant factor influencing the entrapment efficiency of transfersomes, further affecting their transdermal flux in vitro. The fluxes of cinnamic acid from transfersomes were all higher than those from conventional liposomes, and the flux from the optimal transfersome formulation was 3.01-fold higher than that from the conventional liposomes (p < 0.05). An in vivo microdialysis sampling method revealed that the dermal drug concentrations from transfersomes applied on various skin regions were much lower than those required with conventional liposomes. After the administration of drug-containing transfersomes and liposomes on abdominal skin regions of rats for a period of 10 h, the Cmax of cinnamic acid from the compared liposomes was 3.21 ± 0.25 µg/mL and that from the transfersomes was merely 0.59 ± 0.02 µg/mL. The results suggest that transfersomes can be used as carriers to enhance the transdermal delivery of cinnamic acid, and that these vehicles may penetrate the skin in the complete form, given their significant deformability.

Sustainable building materials-recycled aggregate and concrete: a systematic review of properties, modification techniques, and environmental impacts.

Resource utilization of construction and demolition (C&D) waste has great potential to significantly reduce the consumption of natural resources and improve the environment. Meanwhile, establishing a sound policy system and reducing production are the key ways to solve the problem of C&D waste. Numerous studies on C&D waste, recycled concrete aggregate (RA), and recycled aggregate concrete (RAC) have been reported in the literature, with few systematic summaries. From a global perspective, this paper assessed the current situation of C&D waste and the countermeasure of several major economies. Then, this paper systematically introduces the composition structure and characteristics of RA. Modification techniques from macro and micro perspectives of RA and its effect on RAC were also presented. Paper also reviews the environmental impacts of RA and RAC. The results showed that bonded mortar was the most significant defect of RA than natural aggregate (NA). Thus, RA weakened RAC's microstructure, workability, mechanical properties, and durability. The research on the modification of RA mainly focused on removing bonded mortar and enhancing bonded mortar containing physical or chemical methods. Enhancing bonded mortar was a more effective method than removing bonded mortar. Carbonation and microbially induced calcium carbonate precipitation were highly efficient and environmentally friendly for RA modification. Research progress in quantifying the environmental impacts associated with concrete from waste materials through the LCA methodology is presented. Suggestions and an outlook were given on the critical issues facing RA and RAC. We expect that this work can provide more technical support for C&D waste utilization.

Speciation distribution and leaching behavior of heavy metals in coal gasification fine ash: Influence of particle size, carbon content and mineral composition.

In this study, the occurrence and distribution of heavy metals in coal gasification fine ash (CGFA) with different particle sizes were investigated to ensure safer disposal and utilization strategies for CGFA. These measures are critical to sustainable industrial practices. This study investigates the distribution and leachability of heavy metals in CGFA, analyzing how these factors vary with particle size, carbon content, and mineral composition. The results demonstrated that larger CGFA particles (>1 mm) encapsulated up to 70 % more heavy metals than smaller particles (<0.1 mm). Cr and Zn were present in higher concentrations in larger CGFA particles, whereas volatile elements such as Zn, Hg, Se, and Pb were found in relatively higher contents in finer CGFA particles. At least 70 % of Hg in CGFA was present in an acid-soluble form of speciation, whereas Cd, Zn, and Pb were mostly present in a reducible form of speciation, which could be attributed to the presence of franklinite. More than 40 % of Cd and Zn in fine CGFA particles exist in an acid-soluble form. With the exception of CGFA_1.18, Se in CGFA mainly existed in an oxidizable form at a ratio of 60 %-80 %. This could be attributed to the presence of bassanite particles as well as the higher affinity of Se for S. In contrast, Cr, Cu, and As were mostly present in residual speciation forms owing to their parasitism in quartz, sillimanite, and amorphous Fe solid solution in CGFA. Additionally, the study revealed that there was no significant relationship between heavy metal content, leaching behavior, and carbon content in CGFA. Based on combined analyses using toxicity characteristic leaching procedure (TCLP) leaching concentrations and risk assessment code (RAC) results, it is recommended to focus on the environmental risks posed by Cd, Cr, Pb, Zn, and Hg in CGFA during their modification and utilization processes.

Study on the relation between macro-mechanical properties and micro-structure of geopolymers with different activator modulus.

The fly ash-based geopolymer (FABG) containing slag has distinct advantages in field applications. In this work, given that the activator modulus is a significant parameter affecting the properties of FABG, the influence mechanism of activator modulus (SiO2/Na2O from 1.1 to 1.5) on the macro-mechanical properties and micro-structure composition of FABG containing slag is explored. According to the experimental results, the early product of FABG containing slag is mainly C-A-S-H gel, and N-(C)-A-S-H gel with high cross-linking degree is formed at a later stage. Both C-A-S-H and N-A-S-H gels are distinguished in reaction products by using 29Si NMR. The Si/Al ratio of N-A-S-H gel and C-A-S-H gel decreases with the increase of modulus, resulting in an increase of MCL in C-A-S-H. Appropriate activator modulus can effectively activate slag and fly ash to yield more gels and form a more uniform and dense micro-structure, resulting in a lower threshold pore size and macroporosity, and an associated increase of the material strength. Meanwhile, the gel amount has a positive effect on the strength development in the FABG.

Targeting ENPP1 for cancer immunotherapy: Killing two birds with one stone.

Cancer immunotherapy, particularly with immune checkpoint inhibitors, has revolutionized the paradigm of cancer treatment. Nevertheless, the efficacy of cancer immunotherapy remains limited in most clinical settings due to the lack of a preexisting antitumor T-cell response in tumors. Therefore, the clinical outcomes of cancer immunotherapy must be improved crucially. With increased awareness of the importance of the innate immune response in the recruitment of T cells, as well as the onset and maintenance of the T cell response, great interest has been shown in activating the cGAS-STING signaling pathway to awaken the innate immune response, thereby orchestrating both innate and adaptive immune responses to induce tumor clearance. However, tumor cells have evolved to overexpress ectonucleotide pyrophosphate phosphodiesterase 1 (ENPP1), which degrades the immunotransmitter 2',3'-cGAMP and promotes the production of immune-suppressing adenosine, resulting in inhibition of the anticancer immune response in the tumor microenvironment. Clinically, ENPP1 overexpression is closely associated with poor prognosis in patients with cancer. Conversely, depleting or inhibiting ENPP1 has been verified to elevate extracellular 2',3'-cGAMP levels and inhibit the generation of adenosine, thereby reinvigorating the anticancer immune response for tumor elimination. A variety of ENPP1 inhibitors have recently been developed and have demonstrated significant promise for cancer immunotherapy. In this review, we provide an overview of ENPP1, dissect its immunosuppressive mechanisms, and discuss the development of ENPP1 inhibitors with the potential to further improve the efficacy of cancer immunotherapy.

Lipoxin A4 ameliorates knee osteoarthritis progression in rats by antagonizing ferroptosis through activation of the ESR2/LPAR3/Nrf2 axis in synovial fibroblast-like synoviocytes.

BACKGROUND: Our previous studies have shown that lipoxin A4 (LXA4) can serve as a potential biomarker for assessing the efficacy of exercise therapy in knee osteoarthritis (KOA), and fibroblast-like synoviocytes (FLSs) may play a crucial role in KOA pain as well as in the progression of the pathology. OBJECTIVE: By analyzing the GSE29746 dataset and collecting synovial samples from patients with different Kellgren-Lawrence (KL) grades for validation, we focused on exploring the potential effect of LXA4 on ferroptosis in FLSs through the ESR2/LPAR3/Nrf2 axis to alleviate pain and pathological advancement in KOA. METHODS: The association between FLSs ferroptosis and chondrocyte matrix degradation was explored by cell co-culture. We overexpressed and knocked down LPAR3 in vitro to explore its potential mechanism in FLSs. A rat model of monosodium iodoacetate (MIA)-induced KOA was constructed and intervened with moderate-intensity treadmill exercise and intraperitoneal injection of PHTPP to investigate the effects of the LXA4 intracellular receptor ESR2 on exercise therapy. RESULTS: ESR2, LPAR3, and GPX4 levels in the synovium decreased with increasing KL grade. After LXA4 intervention in the co-culture system, GPX4, LPAR3, and ESR2 were upregulated in FLSs, collagen II was upregulated in chondrocytes, and MMP3 and ADAM9 were downregulated. LPAR3 overexpression upregulated the expression of GPX4, Nrf2, and SOD1 in FLSs, while downregulating the expression of MMP13 and MMP3; LPAR3 knockdown reversed these changes. Moderate-intensity platform training improved the behavioral manifestations of pain in KOA rats, whereas PHTPP treatment partially reversed the improvement in synovial and cartilage pathologies induced by platform training. CONCLUSION: LXA4 inhibited FLSs ferroptosis by activating the ESR2/LPAR3/Nrf2 axis, thereby alleviating the pain and pathological progression of KOA. This study brings a new target for the treatment of KOA and also leads to a deeper understanding of the potential mechanisms of exercise therapy for KOA.