Xinming Yang

Background: Tensor‐valued diffusion magnetic resonance imaging enables the separation of total kurtosis into isotropic and anisotropic components, offering improved specificity over conventional diffusion kurtosis imaging. In this study, we introduce a novel framework for detecting anisotropic‐isotropic kurtosis mismatch and evaluate its relevance in experimental ischemic stroke. Methods: Tensor‐valued diffusion magnetic resonance imaging was performed in a rat model of middle cerebral artery occlusion. Metrics, including anisotropic mean kurtosis and isotropic mean kurtosis, were quantified to assess microstructural tissue heterogeneity. Histologic validation was conducted using coregistered tissue sections. Results: We observed significant mismatches between mean diffusivity, mean kurtosis, as well as specifically in anisotropic mean kurtosis and isotropic mean kurtosis in ischemic regions. Notably, anisotropic mean kurtosis and isotropic mean kurtosis exhibited statistically significant alterations compared with contralateral regions. Moreover, these metrics strongly correlated with pathologic findings. The observed mismatch highlighted microstructurally distinct subregions within the lesion. Conclusions: This study establishes an in vivo framework for characterizing anisotropic‐isotropic kurtosis mismatch in an experimental stroke model. By quantifying the isotropic mean kurtosis/anisotropic mean kurtosis mismatch, tensor‐valued diffusion magnetic resonance imaging provides a more specific mechanistic characterization of diffusion heterogeneity than conventional diffusion tensor imaging and diffusion kurtosis imaging metrics, supporting its use as a preclinical tool for investigating microstructural alterations in ischemic brain tissue.

Castration-resistant prostate cancer (CRPC) lethality arises from epigenetic-driven resistance to androgen deprivation therapy (ADT). Here, we uncover a compensatory epigenetic switch between DNA methylation and H3K27me3-mediated repression as a critical barrier to epigenetic therapy in CRPC. Integrative multiomics analyses reveal that DNMT inhibitors (DNMTis) trigger EZH2-dependent H3K27me3 accumulation at the ADAMTS1 locus—a master collagenase essential for extracellular matrix (ECM) remodeling—perpetuating fibrotic niche formation and therapy resistance. Dual targeting of DNMTs and EZH2 disrupts this epigenetic plasticity, synergistically reactivating ADAMTS1 to degrade collagen-rich stroma, suppress FAK/MAPK mechanotransduction signaling, and reverse epithelial–mesenchymal transition (EMT). Crucially, in immunocompetent models, this strategy achieves >90% tumor suppression and reverses immunosuppression by enhancing cytotoxic CD8 ⁺ T cell infiltration 11.4-fold while depleting immunosuppressive macrophages and Tregs. Mechanistically, dual therapy inactivates the FAK/MAPK/EMT axis via ADAMTS1-mediated ECM degradation, overcoming stromal-mediated resistance. Our work establishes epigenetic-ECM coevolution as a hallmark of CRPC and provides a rationally designed combination therapy to dismantle the therapy-resistant niche.

Silver( i )-mediated “open-to-closed” conformational change of malate dehydrogenase (MDH) at the active-site leads to the allosteric inhibition of the enzyme upon binding of Ag ⁺ to the Cys ²⁵¹ residue.

Drug resistance in tumor cells remains a persistent clinical challenge in the pursuit of effective anticancer therapy. XIAP, a member of the inhibitor of apoptosis protein (IAP) family, suppresses apoptosis via its Baculovirus IAP Repeat (BIR) domains and is responsible for drug resistance in various human cancers. Therefore, XIAP has attracted significant attention as a potential therapeutic target. However, no XIAP inhibitor is available for clinical use to date. In this study, we surprisingly observed that arsenic trioxide (ATO) induced a rapid depletion of XIAP in different cancer cells. Mechanistic studies revealed that arsenic attacked the cysteine residues of BIR domains and directly bound to XIAP, resulting in the release of zinc ions from this protein. Arsenic-XIAP binding suppressed the normal anti-apoptosis functions of BIR domains, and led to the ubiquitination-dependent degradation of XIAP. Importantly, we further demonstrate that arsenic sensitized a variety of apoptosis-resistant cancer cells, including patient-derived colon cancer organoids, to the chemotherapy drug using cisplatin as a showcase. These findings suggest that targeting XIAP with ATO offers an attractive strategy for combating apoptosis-resistant cancers in clinical practice.

Copper is an essential trace element for the human body, and its requirement for optimistic immune functions has been recognized for decades. How copper is involved in the innate immune pathway, however, remains to be clarified. Here, we report that copper serves as a signal molecule to regulate the kinase activity of alpha-kinase 1 (ALPK1), a cytosolic pattern-recognition receptor (PRR), and therefore promotes host cell defense against bacterial infection. We show that in response to infection, host cells actively accumulate copper in the cytosol, and the accumulated cytosolic copper enhances host cell defense against evading pathogens, including intracellular and, unexpectedly, extracellular bacteria. Subsequently, we demonstrate that copper activates the innate immune pathway of host cells in an ALPK1-dependent manner. Further mechanistic studies reveal that copper binds to ALPK1 directly and is essential for the kinase activity of this cytosolic PRR. Moreover, the binding of copper to ALPK1 enhances the sensitivity of ALPK1 to the bacterial metabolite ADP-heptose and eventually prompts host cells to elicit an enhanced immune response during bacterial infection. Finally, using a zebrafish in vivo model, we show that a copper-treated host shows an increased production of proinflammatory cytokines, enhanced recruitment of phagosome cells, and promoted bacterial clearance. Our findings uncover a previously unrecognized role of copper in the modulation of host innate immune response against bacterial pathogens and advance our knowledge on the cross talk between cytosolic copper homeostasis and immune system.

Objective: The aim of this study was to explore the safety of xenogenic acellular dermal matrix for tracheal reconstruction and to explore the process and effectiveness of mucosal repair. Methods: A total of 22 rabbits were divided into the control group and the experimental group. A 3-ring, 120-degree tracheal patch was resected, and the tracheal wall was reconstructed by xenogenic acellular dermal matrix (experimental group) or cervical fascia (control group). Symptoms of the animals, morphology, and micromorphology of the reconstructed tracheas area were evaluated at 1, 4, 8, 12, 16, and 24 weeks postoperatively. Results: In the control group, 1 rabbit got subcutaneous emphysema and the rabbit died of airway obstruction. Tracheal stenosis was observed in all the animals. In the experimental group, no animal showed ingrowth of granulation tissue or accumulation of secretion of the trachea. The acellular dermal matrix got rapidly vascularized and epithelized with ciliated cells. Goblet cells could be observed 24 weeks postoperatively. Conclusion: The tracheas were successfully reconstructed by the acellular dermal matrix, and they are stable with well-functional epithelial lining. This is a simple, safe, and effective surgical method with few complications. As a medical device, this thin membrane would expand the choice of repair materials during tracheal reconstruction. Cite this article as: Li P, Li S, Li J, Yang X. Application of xenogenic acellular dermal matrix for reconstruction of cervical tracheal defects in a rabbit model. B-ENT. 2023;19(2):74-79.

We report for the first time that antimicrobial Ag ⁺ targets the glycolytic pathway through inhibiting the key enzyme of GAPDH.

Despite the broad-spectrum antimicrobial activities of silver, its internal usage is restricted, owing to the toxicity. Strategies to enhance its efficacy are highly desirable but rely heavily on the understanding of its molecular mechanism of action. However, up to now, no direct silver-targeting proteins have been mined at a proteome-wide scale, which hinders systemic studies on the biological pathways interrupted by silver. Herein, we build up a unique system, namely liquid chromatography gel electrophoresis inductively coupled plasma mass spectrometry (LC-GE-ICP-MS), allowing 34 proteins directly bound by silver ions to be identified in Escherichia coli. By using integrated omic approaches, including metalloproteomics, metabolomics, bioinformatics, and systemic biology, we delineated the first dynamic antimicrobial actions of silver (Ag⁺) in E. coli, i.e., it primarily damages multiple enzymes in glycolysis and tricarboxylic acid (TCA) cycle, leading to the stalling of the oxidative branch of the TCA cycle and an adaptive metabolic divergence to the reductive glyoxylate pathway. It then further damages the adaptive glyoxylate pathway and suppresses the cellular oxidative stress responses, causing systemic damages and death of the bacterium. To harness these novel findings, we coadministrated metabolites involved in the Krebs cycles with Ag⁺ and found that they can significantly potentiate the efficacy of silver both in vitro and in an animal model. Our study reveals the comprehensive and dynamic mechanisms of Ag⁺ toxicity in E. coli cells and offers a novel and general approach for deciphering molecular mechanisms of metallodrugs in various pathogens and cells to facilitate the development of new therapeutics.

Small molecule-based fluorescent probes offer great opportunities for specifically tracking proteins in living systems with minimal perturbation on the protein function and localization. Herein, we report a small green fluorescent probe (Ni²⁺-NTA-AF) consisting of a Ni²⁺-NTA moiety, a fluorescein, and an arylazide group, that binds specifically to His₆-tagged proteins with fluorescence enhancement in vitro upon photoactivation of the arylazide group. Importantly, the probe can cross the cell membranes and stoichiometrically label His₆-tagged proteins rapidly (∼15 min) in living prokaryotic and eukaryotic cells exemplified by a DNA repair protein Xeroderma pigmentosum group A (XPA). Using the probe, we successfully visualized Sirtuin 5, which is localized to the mitochondria. This probe exhibits high quantum yields and improved solubility, offering a new opportunity for imaging intracellular His₆-tagged proteins inside living cells with better contrast.

Urease as a potential target of antimicrobial drugs has received considerable attention given its versatile roles in microbial infection. Development of effective urease inhibitors, however, is a significant challenge due to the deeply buried active site and highly specific substrate of a bacterial urease. Conventionally, urease inhibitors are designed by either targeting the active site or mimicking substrate of urease, which is not efficient. Up to now, only one effective inhibitor—acetohydroxamic acid (AHA)—is clinically available, but it has adverse side effects. Herein, we demonstrate that a clinically used drug, colloidal bismuth subcitrate, utilizes an unusual way to inhibit urease activity, i.e., disruption of urease maturation process via functional perturbation of a metallochaperone, UreG. Similar phenomena were also observed in various pathogenic bacteria, suggesting that UreG may serve as a general target for design of new types of urease inhibitors. Using Helicobacter pylori UreG as a showcase, by virtual screening combined with experimental validation, we show that two compounds targeting UreG also efficiently inhibited urease activity with inhibitory concentration (IC)₅₀ values of micromolar level, resulting in attenuated virulence of the pathogen. We further demonstrate the efficacy of the compounds in a mammalian cell infection model. This study opens up a new opportunity for the design of more effective urease inhibitors and clearly indicates that metallochaperones involved in the maturation of important microbial metalloenzymes serve as new targets for devising a new type of antimicrobial drugs. Urease, a metalloenzyme that catalyzes the hydrolysis of urea, plays important roles in the survival and virulence of many microbial pathogens, and has long been considered an important drug target for the development of novel antimicrobials. However, its deeply buried active site and highly specific substrate of bacterial urease make it very challenging to design effective urease inhibitors by conventional approaches. In this study, we reveal that a bismuth-based drug (colloidal bismuth subcitrate) inhibits urease activity in an unusual way. This drug binds the urease accessary protein UreG and inhibits its GTPase activity, thus perturbing nickel insertion into the apo-urease, a process called urease maturation. UreG is therefore proposed as an alternative target for the development of urease inhibitors. Using H. pylori UreG as an example, combined with virtual screening and experimental validation, we further show that several small molecules that bind and functionally disrupt UreG could indeed inhibit urease activity in bacteria and in a cell infection model and possess potent antimicrobial activity. In summary, we discovered metallochaperone UreG as a new target for the design of urease inhibitors. Such a strategy should have a broad application in the development of metalloenzyme inhibitors.