MPI-VGAE: protein-metabolite enzymatic reaction link learning by variational graph autoencoders.

Enzymatic reactions are crucial to explore the mechanistic function of metabolites and proteins in cellular processes and to understand the etiology of diseases. The increasing number of interconnected metabolic reactions allows the development of in silico deep learning-based methods to discover new enzymatic reaction links between metabolites and proteins to further expand the landscape of existing metabolite-protein interactome. Computational approaches to predict the enzymatic reaction link by metabolite-protein interaction (MPI) prediction are still very limited. In this study, we developed a Variational Graph Autoencoders (VGAE)-based framework to predict MPI in genome-scale heterogeneous enzymatic reaction networks across ten organisms. By incorporating molecular features of metabolites and proteins as well as neighboring information in the MPI networks, our MPI-VGAE predictor achieved the best predictive performance compared to other machine learning methods. Moreover, when applying the MPI-VGAE framework to reconstruct hundreds of metabolic pathways, functional enzymatic reaction networks and a metabolite-metabolite interaction network, our method showed the most robust performance among all scenarios. To the best of our knowledge, this is the first MPI predictor by VGAE for enzymatic reaction link prediction. Furthermore, we implemented the MPI-VGAE framework to reconstruct the disease-specific MPI network based on the disrupted metabolites and proteins in Alzheimer's disease and colorectal cancer, respectively. A substantial number of novel enzymatic reaction links were identified. We further validated and explored the interactions of these enzymatic reactions using molecular docking. These results highlight the potential of the MPI-VGAE framework for the discovery of novel disease-related enzymatic reactions and facilitate the study of the disrupted metabolisms in diseases.

Predicting Collision Cross-Section Values for Small Molecules through Chemical Class-Based Multimodal Graph Attention Network.

Libraries of collision cross-section (CCS) values have the potential to facilitate compound identification in metabolomics. Although computational methods provide an opportunity to increase library size rapidly, accurate prediction of CCS values remains challenging due to the structural diversity of small molecules. Here, we developed a machine learning (ML) model that integrates graph attention networks and multimodal molecular representations to predict CCS values on the basis of chemical class. Our approach, referred to as MGAT-CCS, had superior performance in comparison to other ML models in CCS prediction. MGAT-CCS achieved a median relative error of 0.47%/1.14% (positive/negative mode) and 1.40%/1.63% (positive/negative mode) for lipids and metabolites, respectively. When MGAT-CCS was applied to real-world metabolomics data, it reduced the number of false metabolite candidates by roughly 25% across multiple sample types ranging from plasma and urine to cells. To facilitate its application, we developed a user-friendly stand-alone web server for MGAT-CCS that is freely available at https://mgat-ccs-web.onrender.com. This work represents a step forward in predicting CCS values and can potentially facilitate the identification of small molecules when using ion mobility spectrometry coupled with mass spectrometry.

Endoplasmic reticulum stress-related protein GRP78 and CHOP levels in synovial fluid correlate with disease progression of primary knee osteoarthritis: A cross-sectional study.

BACKGROUND: Endoplasmic reticulum (ER) stress has been shown to play an important role in osteoarthritis (OA). OBJECTIVE: This study was aimed at assessing the relationship of endoplasmic reticulum (ER) stress-related glucose-regulated protein 78 (GRP78) and CCAAT/enhancer-binding protein homologous protein (CHOP) concentrations in the serum/synovial fluid (SF) with disease severity of primary knee osteoarthritis (pkOA). METHODS: Patients with pkOA together with healthy individuals were consecutively recruited from our hospital. The levels of GRP78 and CHOP in serum / SF were detected using enzyme-linked immunosorbent assay. The levels of IL-6 and MMP-3 were also examined. Radiographic progression of pkOA was evaluated based on Kellgren-Lawrence (K-L) grades. Receiver Operating Characteristic (ROC) curves were used to assess the diagnostic value of GRP78/CHOP levels with regard to K-L grades. The assessment of clinical severity was conducted using the visual analogue scale (VAS), Oxford knee score (OKS), and Lequesne algofunctional index (LAI). RESULTS: A total of 140 pkOA patients and 140 healthy individuals were included. Serum GRP78 and CHOP levels in pkOA patients were not significantly different from those in healthy individuals. The SF GRP78 and CHOP levels in healthy controls were not detected due to ethical reasons. Compared to those with K-L grade 2 and 3, the pkOA patients with K-L grade 4 had higher GRP78 and CHOP levels in the SF with statistical significance. In addition, the pkOA patients with K-L grade 3 exhibited drastically upregulated GRP78 and CHOP concentrations in the SF compared to those with K-L grade 2. Positive correlations of GRP78 and CHOP levels with K-L grades, IL-6, and MMP-3 levels in the SF were observed. ROC curve analysis indicated that both GRP78 and CHOP levels may act as decent indicators with regard to OA. GRP78 and CHOP concentrations in the SF were positively correlated with VAS/LAI score and negatively associated with OKS score. CONCLUSION: The study indicated that GRP78 and CHOP levels in the SF but not the serum were positively correlated with disease severity of pkOA.

Measles epidemiology and viral nucleoprotein gene evolution in Shandong Province, China.

Measles, caused by measles virus (MeV), has not been eradicated in many regions and countries, threatening human health. Thus, it is beneficial for measles elimination to understand measles epidemiology and molecular evolution of key viral genes, such as nucleoprotein (N) gene. Based on public data, measles epidemiological information and MeV N gene sequences reported in Shandong Province, China were comprehensively collected and systematically analyzed. The results showed a positive correlation between population density and measles incidence (r = +0.31), while negative correlations were found between measles incidence and healthcare condition (r = -0.21) as well as average routine vaccination rate (r = -0.11). Additionally, the predominant lineage of MeV in Shandong was formed by genotype H1 strains, and the time of the most recent common ancestor of the N gene of MeV genotype H1 in Shandong traced back to 1987 (95% highest posterior density, 1984-1990) with relatively rapid evolution (mean rate, 1.267 × 10-3 substitutions/site/year). The genetic diversity of MeV N gene increased with the substantial emergence of major divergent clades of genotype H1 before 2005 and then remained relatively high and stable. In summary, these findings provided a significant insight into the measles elimination.

cGAS promotes sepsis in radiotherapy of cancer by up-regulating caspase-11 signaling.

Radiotherapy is the most common strategy in the treatment of cancer. However, radiation-induced acute complications, in particular sepsis, render patients in a life-threatening status or lead to delay of therapy that largely influences patients' overall responses. The understanding of sepsis in radiotherapy is currently scant and effective medicine is not available by far. Here, with WT mice as control, we challenged mice deficient to cGas, Caspase-11, Gsdmd or Asc with cecal ligation and puncture (CLP, a sepsis model) after a treatment of thorax irradiation. We found that radiation robustly upgraded caspase-11 pathway in irradiated region and consequently deteriorated lung injury and mortality in the sepsis model. cGas knockout markedly attenuated radiation-upgraded caspase-11 and restored sepsis. Deficiency of non-canonical inflammasome, caspase-11 and the downstream GSDMD, rather than an AIM2 inflammasome component, ASC, dramatically protected against radiation-promoted injury and mortality in septic mice. The protection may attribute to the inhibition of caspase-11-mediated pyroptosis in endothelial cells of the lung. Thus, blocking cGAS/caspase-11 signaling would be an adjuvant treatment strategy for preventing sepsis in radiotherapy of cancer.

Ethyl pyruvate protects against sepsis-associated encephalopathy through inhibiting the NLRP3 inflammasome.

BACKGROUND: With the advance of antibiotics and life support therapy, the mortality of sepsis has been decreasing in recent years. However, the incidence of sepsis-associated encephalopathy (SAE), a common complication of sepsis, is still high. There are few effective therapies to treat clinical SAE. We previously found that ethyl pyruvate (EP), a metabolite derivative, is able to effectively inhibit the NLRP3 inflammasome activation. Administration of ethyl pyruvate protects mice against polymicrobial sepsis in cecal ligation and puncture (CLP) model. The aim of present study is to investigate if ethyl pyruvate is able to attenuate SAE. METHODS: After CLP, C57BL/6 mice were intraperitoneally or intrathecally injected with saline or ethyl pyruvate using the sham-operated mice as control. New Object Recognition (NOR) and Morris Water Maze (MWM) were conducted to determine the cognitive function. Brain pathology was assessed via immunohistochemistry. To investigate the mechanisms by which ethyl pyruvate prevent SAE, the activation of NLRP3 in the hippocampus and the microglia were determined using western blotting, and cognitive function, microglia activation, and neurogenesis were assessed using WT, Nlrp3-/- and Asc-/- mice in the sublethal CLP model. In addition, Nlrp3-/- and Asc-/- mice treated with saline or ethyl pyruvate were subjected to CLP. RESULTS: Ethyl pyruvate treatment significantly attenuated CLP-induced cognitive decline, microglia activation, and impaired neurogenesis. In addition, EP significantly decreased the NLRP3 level in the hippocampus of the CLP mice, and inhibited the cleavage of IL-1ß induced by NLRP3 inflammsome in microglia. NLRP3 and ASC deficiency demonstrated similar protective effects against SAE. Nlrp3-/- and Asc-/- mice significantly improved cognitive function and brain pathology when compared with WT mice in the CLP models. Moreover, ethyl pyruvate did not have additional effects against SAE in Nlrp3-/- and Asc-/- mice. CONCLUSION: The results demonstrated that ethyl pyruvate confers protection against SAE through inhibiting the NLRP3 inflammasome.

Silencing IFNγ inhibits A1 astrocytes and attenuates neurogenesis decline and cognitive impairment in endotoxemia.

Cognitive impairment, acute or long-term, is a common complication in patients with severe bacterial infection. However, the underlying mechanisms are not fully verified and effective medicine is not available in clinics. Interferon gamma (IFNγ) is a pivotal cytokine against infection and is believed to be a tune in homeostasis of cognitive function. Here, we collected blood and cerebrospinal fluid (CF) from human subjects and mice, and found that plasma and CF levels of IFNγ were significantly increased in septic patients and endotoxin-challenged mice when compared with healthy controls. IFNγ signaling was boosted in the hippocampus of mice after a challenge of lipopolysaccharide (LPS), which was accompanied with cognitive impairment and decline of neurogenesis. Deficiency of IFNγ or its receptor (IFNγR) dramatically attenuated microglia-induced A1 astrocytes and consequently restored neurogenesis and cognitive function in endotoxemia mice model. Using primary microglia, astrocytes and neurons, we found that IFNγ remarkably increased LPS-mediated release of TNFα and IL-1α in microglia and consequently induced the transformation of astrocyte to A1 subtype, which ultimately resulted in neuron damage. Thus, IFNγ promotes cognitive impairment in endotoxemia by enhancing microglia-induced A1 astrocytes. Targeting IFNγ would be a novel strategy for preventing or treating cognitive dysfunction in patients with Gram-negative infection.

DNA damage/cGAS-triggered up-regulation of MALAT1 promotes undesirable inflammatory responses in radiotherapy of cancer.

Radiotherapy is the most common strategy for treating cancer. However, the radiation-induced inflammatory responses, acute or chronic, in the normal tissues of the irradiated region may result in undesirable side effects, such as lung injury and atherosclerosis. MALAT1 is believed to function in the onset, development, progression and metastasis of various cancers. Silencing MALAT1 may be a promising treatment for rescuing cancer. Nevertheless, whether MALAT1 promotes the radiation-induced undesirable inflammatory response is still uncovered. The present study reveals that radiation-induced DNA damage triggers cGAS signaling and subsequently increases the expression of MALAT1. Overexpression of MALAT1 inhibits the function of miR146a in the suppression of STAT1, which results in the boost of adhesion molecules and eventually induces acute lung injury and atherosclerosis. Thus, silencing MALAT1 may facilitate the reduction of radiation-induced acute and chronic complications in the radiotherapy of cancer.

TNF-α-Induced NOD2 and RIP2 Contribute to the Up-Regulation of Cytokines Induced by MDP in Monocytic THP-1 Cells.

Nucleotide-binding oligomerization domain containing 2 (NOD2)-induced signal transduction and cytokine production is regulated by a number of factors. However, the feedback effect of the pro-inflammatory TNF-α on NOD2-induced inflammation is not fully understood. In this study, we found unexpectedly that TNF-α up-regulated NOD2 ligand MDP-induced production of the CXC chemokines, including CXCL1, 2, and 8, and the pro-inflammatory cytokines, including IL-1ß, IL-6, and TNF-α, in a dose-dependent manner at both mRNA and protein levels in monocytic THP-1 cells. Though TNF-α induced the up-regulation of ubiquitin-editing enzyme A20, an important negative regulator for Toll-like receptor- and NOD2-induced inflammatory responses, the over-expression of A20 by gene transfer did not reversed MDP-induced production of cytokines, suggested that A20 did not regulate the functions of NOD2 in THP-1 cells. Meanwhile, we found that TNF-α up-regulated NOD2 and its down-stream adaptor protein RIP2 at both mRNA and protein levels. MDP induced the activation of ERK, JNK, p38 and NF-κB, and TNF-α pre-treatment augmented this activation. The results from pharmacological inhibition assay showed that cytokine production was dependent on MAPK signaling. In addition, we found that the pre-treatment of THP-1 cells with MDP down-regulated the mRNA levels of cytokine induced by MDP re-treatment. MDP pre-treatment up-regulated NOD2, but down-regulated RIP2, and down-regulated NOD2 signal transduction induced by MDP re-stimulation. Taking together, these results suggested that TNF-α is a positive regulator for NOD2 functions via up-regulation of NOD2 and its signal adaptor RIP2, and TNF-α-induced A20 does not regulate MDP-induced inflammatory responses in THP-1 cells. J. Cell. Biochem. 119: 5072-5081, 2018. © 2017 Wiley Periodicals, Inc.

The disappearance of femoral head and neck resulting from extensive bone defect caused by secondary syphilis: a case report and literature review.

BACKGROUND: Treponema Pallidum (TP), the pathogen of syphilis, commonly infects bones in cases of congenital and tertiary syphilis, but it is rare in the primary and secondary stages. With its mild symptoms and rare clinical findings, it might be easy to dismiss the diagnosis of early syphilis. Usually, effective results can be achieved after the conventional strategy of antibiotic treatments, mainly penicillin. To our knowledge, our case is so far the most serious reported case of destructive bone lesion in secondary syphilis, and our treatment for the case is the first strategy using total hip arthroplasty in secondary syphilis. CASE PRESENTATION: We present the case of a 71-year-old man with local repeated pain and dysfunction in the right hip. Radiologic examinations showed the disappearance of the ipsilateral femoral head and neck. After excluding the aetiologies of cancer metastasis and tuberculosis, we confirmed the diagnosis of syphilitic arthritis. The patient received the medical treatment of antibiotics and the surgical treatment of total hip arthroplasty. At the follow-up of 1, 3, and 5.5 years after the operation, the patient presented with a pain-free and functional hip prosthesis without local signs of infection and loosening. CONCLUSIONS: This report highlights the difficulties of early diagnosis of secondary syphilis with bone involvement. Bone defect of the femur with secondary syphilis, especially at the proximal femur, was an extremely rare complication in the previous reports. Our case was the first case of a patient who experienced the disappearance of femoral head and neck caused by secondary syphilis. Follow-up after the operation proved the successful treatment of the extensive bone defect of femur by total hip arthroplasty.

Ultrasound Evaluation of Carotid Atherosclerosis in Post-Radiotherapy Nasopharyngeal Carcinoma Patients, Type 2 Diabetics, and Healthy Controls.

Purpose To comprehensively evaluate and compare the degree of carotid atherosclerosis in patients treated with radiotherapy (RT) for nasopharyngeal carcinoma (NPC) and in patients with type 2 diabetes mellitus (DM), and using healthy subjects as controls. Materials and Methods The present study recruited 69 post-RT NPC patients without conventional cardiovascular risk factors, 70 type 2 diabetic patients without previous RT, and 76 healthy controls without conventional cardiovascular risk factors and previous RT. For each participant, 5 carotid atherosclerotic parameters, namely carotid intima-media thickness (CIMT), carotid arterial stiffness (CAS), presence of carotid plaque, carotid plaque score, and presence of ≥ 50 % carotid stenosis, were assessed using ultrasonography. The differences in these carotid atherosclerotic parameters between study groups were compared using ANCOVA or logistic regression after the adjustment for age and gender. Multiple comparisons were corrected using the Benjamini-Hochberg false discovery rate. Results Post-RT NPC patients and type 2 diabetics had a significantly higher CIMT, CAS and carotid plaque burden compared to the healthy subjects (corrected P-value, Pcor < 0.05). In addition, carotid atherosclerosis in post-RT NPC patients tended to be more severe with significantly higher CAS and carotid plaque burden than that in type 2 diabetics (Pcor < 0.05). Conclusion Neck RT for NPC is an independent risk factor of carotid atherosclerosis, and radiation induces more severe carotid atherosclerosis in post-RT NPC patients. Thus, assessment of carotid atherosclerosis using ultrasonography may be necessary for these patients and should be indicated in the routine follow-up of NPC.

High levels of soil calcium and clay facilitate the recovery and stability of organic carbon: Insights from different land uses in the karst of China.

Soil organic carbon (SOC) is a crucial medium of the global carbon cycle and is profoundly affected by multiple factors, such as climate and management practices. However, interactions between different SOC fractions and land-use change have remained largely unexplored in karst ecosystems with widespread rock outcrops. Owing to the inherent heterogeneity and divergent response of SOC to land-use change, soil samples with close depth were collected from four typical land-use types (cropland, grassland, shrubland, and forestland) in the karst rocky desertification area of China. The aim of this study was to explore the responses of SOC dynamics to land-use types and underlying mechanism. The results showed that land-use type significantly affected SOC contents and its fractions. Compared with cropland, the other three land uses increased the total organic carbon (TOC), microbial biomass carbon (MBC), and non-labile organic carbon (NLOC) contents by 6.11-129.44%, 32.58-173.73%, and 90.98-347.00%, respectively; this demonstrated that a decrease in both labile and recalcitrant carbon resulted in SOC depletion under agricultural land use. Readily oxidized organic carbon (ROC) ranged from 42 to 69%, accounting for almost half of the TOC in the 0-40-cm soil layer. Cropland soil showed significantly higher ROC:TOC ratios than other land-use types. These results indicated that long-term vegetation restoration decreased SOC activity and improved SOC stability. Greater levels of soil exchangeable calcium (ECa) and clay contents were likely responsible for higher stabilization and then accumulation of SOC after vegetation restoration. The carbon pool index (CPI) rather than the carbon pool management index (CPMI) exhibited consistent variation trend with soil TOC contents among land-use types. Thus, further study is needed to validate the CPMI in evaluating land use effects on soil quality in karst ecosystems. Our findings suggest that land-use patterns characterized by grass or forest could be an effective approach for SOC-sequestration potential and ensure the sustainable use of soil resources in the karst area.

MK-2206 induces cell cycle arrest and apoptosis in HepG2 cells and sensitizes TRAIL-mediated cell death.

It has become evident that AKT inhibitors have great potential in cancer treatment. In this study, we investigate the anticancer activity of MK-2206, a novel AKT inhibitor, on HepG2 hepatocellular carcinoma cell, and to show whether MK-2206 enhances the apoptosis-inducing potential of tumor necrosis factor-related apoptosis-inducing ligand (TRAIL). The cell growth inhibition was evaluated by MTT assay and colony formation assay. Cell cycle distribution was assessed by propidium iodide flow cytometry. Apoptosis was determined by AnnexinV-FITC/PI double staining assay and caspase-9, casapse-7, caspase-3, and PARP cleavage. The results of present study showed that MK-2206-induced G1-phase arrest was associated with a marked decrease in the protein expression of cyclin D1 with concomitant induction of p21 and p27. MK-2206-induced apoptosis was characterized by cleavage of a pro-caspase in a concentration-dependent manner. Moreover, the MAP family kinases p38 kinase and JNK were activated by exposure to MK-2206. SB203580, an p38-specific inhibitor, partially blocked MK-2206-induced death of HepG2 cells and caspase activation. A combination of MK-2206 with TRAIL significantly inhibited growth of TRAIL resistant HepG2 cells. Taken together, our findings provide a new insight to better understand anticancer mechanisms of MK-2206, at least in HepG2 cell. Using of MK-2206 as a potent sensitizer to TRAIL-induced apoptotic cell death offers a promising means of enhancing the efficacy of TRAIL-based HCC treatments.

Genome-scale enzymatic reaction prediction by variational graph autoencoders.

Background: Enzymatic reaction networks are crucial to explore the mechanistic function of metabolites and proteins in biological systems and understanding the etiology of diseases and potential target for drug discovery. The increasing number of metabolic reactions allows the development of deep learning-based methods to discover new enzymatic reactions, which will expand the landscape of existing enzymatic reaction networks to investigate the disrupted metabolisms in diseases. Results: In this study, we propose the MPI-VGAE framework to predict metabolite-protein interactions (MPI) in a genome-scale heterogeneous enzymatic reaction network across ten organisms with thousands of enzymatic reactions. We improved the Variational Graph Autoencoders (VGAE) model to incorporate both molecular features of metabolites and proteins as well as neighboring features to achieve the best predictive performance of MPI. The MPI-VGAE framework showed robust performance in the reconstruction of hundreds of metabolic pathways and five functional enzymatic reaction networks. The MPI-VGAE framework was also applied to a homogenous metabolic reaction network and achieved as high performance as other state-of-art methods. Furthermore, the MPI-VGAE framework could be implemented to reconstruct the disease-specific MPI network based on hundreds of disrupted metabolites and proteins in Alzheimer's disease and colorectal cancer, respectively. A substantial number of new potential enzymatic reactions were predicted and validated by molecular docking. These results highlight the potential of the MPI-VGAE framework for the discovery of novel disease-related enzymatic reactions and drug targets in real-world applications. Data availability and implementation: The MPI-VGAE framework and datasets are publicly accessible on GitHub https://github.com/mmetalab/mpi-vgae . Author Biographies: Cheng Wang received his Ph.D. in Chemistry from The Ohio State Univesity, USA. He is currently a Assistant Professor in School of Public Health at Shandong University, China. His research interests include bioinformatics, machine learning-based approach with applications to biomedical networks. Chuang Yuan is a research assistant at Shandong University. He obtained the MS degree in Biology at the University of Science and Technology of China. His research interests include biochemistry & molecular biology, cell biology, biomedicine, bioinformatics, and computational biology. Yahui Wang is a PhD student in Department of Chemistry at Washington University in St. Louis. Her research interests include biochemistry, mass spectrometry-based metabolomics, and cancer metabolism. Ranran Chen is a master graduate student in School of Public Health at University of Shandong, China. Yuying Shi is a master graduate student in School of Public Health at University of Shandong, China. Gary J. Patti is the Michael and Tana Powell Professor at Washington University in St. Louis, where he holds appointments in the Department of Chemisrty and the Department of Medicine. He is also the Senior Director of the Center for Metabolomics and Isotope Tracing at Washington University. His research interests include metabolomics, bioinformatics, high-throughput mass spectrometry, environmental health, cancer, and aging. Leyi Wei received his Ph.D. in Computer Science from Xiamen University, China. He is currently a Professor in School of Software at Shandong University, China. His research interests include machine learning and its applications to bioinformatics. Qingzhen Hou received his Ph.D. in the Centre for Integrative Bioinformatics VU (IBIVU) from Vrije Universiteit Amsterdam, the Netherlands. Since 2020, He has serveved as the head of Bioinformatics Center in National Institute of Health Data Science of China and Assistant Professor in School of Public Health, Shandong University, China. His areas of research are bioinformatics and computational biophysics. Key points: Genome-scale heterogeneous networks of metabolite-protein interaction (MPI) based on thousands of enzymatic reactions across ten organisms were constructed semi-automatically.An enzymatic reaction prediction method called Metabolite-Protein Interaction Variational Graph Autoencoders (MPI-VGAE) was developed and optimized to achieve higher performance compared with existing machine learning methods by using both molecular features of metabolites and proteins.MPI-VGAE is broadly useful for applications involving the reconstruction of metabolic pathways, functional enzymatic reaction networks, and homogenous networks (e.g., metabolic reaction networks).By implementing MPI-VGAE to Alzheimer's disease and colorectal cancer, we obtained several novel disease-related protein-metabolite reactions with biological meanings. Moreover, we further investigated the reasonable binding details of protein-metabolite interactions using molecular docking approaches which provided useful information for disease mechanism and drug design.

Amplifying the efficacy of ALA-based prodrugs for photodynamic therapy using nanotechnology.

5-aminolevulinic acid (ALA) is a clinically approved prodrug involved in intracellular Heme biosynthesis to produce the natural photosensitizer (PS) Protoporphyrin IX (PpIX). ALA based photodynamic therapy (PDT) has been used to treat various malignant and non-malignant diseases. However, natural ALA has disadvantages such as weak lipophilicity, low stability and poor bioavailability, greatly reducing its clinical performance. The emerging nanotechnology is expected to address these limitations and thus improve the therapeutic outcomes. Herein, we summarized important recent advances in the design of ALA-based prodrugs using nanotechnology to improve the efficacy of PDT. The potential limitations and future perspectives of ALA-based nanomedicines are also briefly presented and discussed.

Applications and prospects of cryo-EM in drug discovery.

Drug discovery is a crucial part of human healthcare and has dramatically benefited human lifespan and life quality in recent centuries, however, it is usually time- and effort-consuming. Structural biology has been demonstrated as a powerful tool to accelerate drug development. Among different techniques, cryo-electron microscopy (cryo-EM) is emerging as the mainstream of structure determination of biomacromolecules in the past decade and has received increasing attention from the pharmaceutical industry. Although cryo-EM still has limitations in resolution, speed and throughput, a growing number of innovative drugs are being developed with the help of cryo-EM. Here, we aim to provide an overview of how cryo-EM techniques are applied to facilitate drug discovery. The development and typical workflow of cryo-EM technique will be briefly introduced, followed by its specific applications in structure-based drug design, fragment-based drug discovery, proteolysis targeting chimeras, antibody drug development and drug repurposing. Besides cryo-EM, drug discovery innovation usually involves other state-of-the-art techniques such as artificial intelligence (AI), which is increasingly active in diverse areas. The combination of cryo-EM and AI provides an opportunity to minimize limitations of cryo-EM such as automation, throughput and interpretation of medium-resolution maps, and tends to be the new direction of future development of cryo-EM. The rapid development of cryo-EM will make it as an indispensable part of modern drug discovery.

Novel 1-hydroxy phenothiazinium-based derivative protects against bacterial sepsis by inhibiting AAK1-mediated LPS internalization and caspase-11 signaling.

Sepsis is a life-threatening syndrome with disturbed host responses to severe infections, accounting for the majority of death in hospitalized patients. However, effective medicines are currently scant in clinics due to the poor understanding of the exact underlying mechanism. We previously found that blocking caspase-11 pathway (human orthologs caspase-4/5) is effective to rescue coagulation-induced organ dysfunction and lethality in sepsis models. Herein, we screened our existing chemical pools established in our lab using bacterial outer membrane vesicle (OMV)-challenged macrophages, and found 7-(diethylamino)-1-hydroxy-phenothiazin-3-ylidene-diethylazanium chloride (PHZ-OH), a novel phenothiazinium-based derivative, was capable of robustly dampening caspase-11-dependent pyroptosis. The in-vitro study both in physics and physiology showed that PHZ-OH targeted AP2-associated protein kinase 1 (AAK1) and thus prevented AAK1-mediated LPS internalization for caspase-11 activation. By using a series of gene-modified mice, our in-vivo study further demonstrated that administration of PHZ-OH significantly protected mice against sepsis-associated coagulation, multiple organ dysfunction, and death. Besides, PHZ-OH showed additional protection on Nlrp3-/- and Casp1-/- mice but not on Casp11-/-, Casp1/11-/-, Msr1-/-, and AAK1 inhibitor-treated mice. These results suggest the critical role of AAK1 on caspase-11 signaling and may provide a new avenue that targeting AAK1-mediated LPS internalization would be a promising therapeutic strategy for sepsis. In particular, PHZ-OH may serve as a favorable molecule and an attractive scaffold in future medicine development for efficient treatment of bacterial sepsis.

In Vitro and In Vivo Demonstration of Ultraefficient and Broad-Spectrum Antibacterial Agents for Photodynamic Antibacterial Chemotherapy.

Increasing threats from both pathogenic infections and antibiotic resistance highlight the pressing demand for nonantibiotic agents and alternative therapies. Herein, we report several new phenothiazinium-based derivatives, which could be readily synthesized via fragment-based assembly, which exhibited remarkable bactericidal activities both in vitro and in vivo. Importantly, in contrast to numerous clinically and preclinically used antibacterial photosensitizers, these compounds were able to eliminate various types of microorganisms, including Gram-(+) Staphylococcus aureus (S. aureus), Gram-(-) Escherichia coli, multidrug-resistant S. aureus, and their associated biofilms, at low drug and light dosages (e.g., 0.21 ng/mL in vitro and 1.63 ng/cm2 in vivo to eradicate S. aureus at 30 J/cm2). This study thus unveils the potential of these novel phenothiaziniums as potent antimicrobial agents for highly efficient photodynamic antibacterial chemotherapy.

Combination of ponatinib with deferoxamine synergistically mitigates ischemic heart injury via simultaneous prevention of necroptosis and ferroptosis.

Necroptosis, ferroptosis and cyclophilin D (Cyp D)-dependent necrosis contribute to myocardial ischemia/reperfusion (I/R) injury, and ponatinib, deferoxamine and cyclosporine are reported to inhibit necroptosis, ferroptosis and Cyp D-dependent necrosis, respectively. This study aims to explore whether the any two combination between ponatinib, deferoxamine and cyclosporine exerts a better cardioprotective effect on I/R injury than single medicine does. The H9c2 cells were subjected to 10 h of hypoxia (H) plus 4 h of reoxygenation (R) to establish H/R injury model. The effects of any two combination between ponatinib, deferoxamine and cyclosporine on H/R injury were examined. On this basis, a I/R injury model in rat hearts was established to focus on the effect of ponatinib, deferoxamine and their combination on myocardial I/R injury and the underlying mechanisms. In H/R-treated H9c2 cells, all three medicines can attenuate H/R injury (decrease in LDH release and necrosis percent). However, only the combination of ponatinib with deferoxamine exerted synergistic effect on reducing H/R injury, showing simultaneous suppression of necroptosis and ferroptosis. Expectedly, administration of ponatinib or deferoxamine either before or after ischemia could suppress necroptosis or ferroptosis in the I/R-treated rat hearts as they did in vitro, concomitant with a decrease in myocardial infarct size and creatine kinase release, and the combination therapy is more efficient than single medication. Based on these observations, we conclude that the combination of ponatinib with deferoxamine reduces myocardial I/R injury via simultaneous inhibition of necroptosis and ferroptosis.

Synergistic effects of FGF-2 and PDGF-BB on angiogenesis and muscle regeneration in rabbit hindlimb ischemia model.

Combinatorial strategy has been used in therapeutic angiogenesis in animal models of peripheral arterial disease (PAD) and coronary artery disease for decades. Previous studies have shown that basic fibroblast growth factor (FGF-2) and platelet-derived growth factor BB (PDGF-BB) proteins together establish functional and stable vascular networks on mouse corneal and also in animal model of hindlimb ischemia. However, the short half life of protein by single injection is not sufficient to achieve effective dosage, repeated and prolonged injection causes systemic toxicity. Here we study the synergistic effects of FGF-2 and PDGF-BB by intramuscular injection of naked plasmid DNA on therapeutic angiogenesis in rabbit model of hindlimb ischemia. We found that transient delivery of FGF-2 and PDGF-BB naked DNA together resulted in greater increases in capillary growth, collateral formation and popliteal blood flow compared with control and single gene delivery. Our data provided novel evidence of beneficial effects of DNA-based FGF-2 and PDFG-BB on muscle repair after ischemic injury. These findings reveal an alternative therapeutic approach in the treatment of ischemic diseases and even in muscular disorders.