Protein Activation Research Articles

Targeting FAP-positive chondrocytes in osteoarthritis: a novel lipid nanoparticle siRNA approach to mitigate cartilage degeneration

BackgroundOsteoarthritis (OA) is a common joint disease that leads to chronic pain and functional limitations. Recent research has revealed soluble fibroblast activation protein (FAP) secreted from OA synovium could degrade type II collagen (Col2) in cartilage to promote the progression of OA. This study aimed to reveal the role of FAP from chondrocytes in OA and develop a novel lipid nanoparticle (LNP)-FAP siRNA delivery system for OA treatment.MethodsThe expression of FAP in the cartilage of knee OA patients was investigated using [68 Ga]Ga-FAPI-04 PET in vivo and immunofluorescence, western blotting, and RT-qPCR in vitro. Cell senescence was determined by senescence-associated β-galactosidase (SA-β-Gal) assay after FAP overexpressing or knockdown in chondrocytes. An OA model with chondrocyte-specific FAP knockout mice was applied to investigate the role of FAP in chondrocyte senescence and OA development. The therapeutic effects of lipid nanoparticle (LNP) @FAP siRNA on cartilage degeneration were evaluated in the rat OA model.ResultsOur study found that higher [68 Ga]Ga-FAPI-04 uptake was detected in knee OA patients by PET/CT scan. FAP mRNA and protein levels were highly expressed in OA-damaged cartilage. Moreover, we found that overexpression of FAP promotes chondrocyte senescence, and the genetic knockout of FAP in chondrocytes alleviates OA. Knockdown FAP by siRNA could alleviate chondrocyte senescence and suppress the NF-κB pathway to reduce the senescence-associated secretory phenotype (SASP). In the rat model of OA, intraarticular injection of LNP@FAP siRNA can reduce senescent cells and ameliorate cartilage destruction.ConclusionFAP-positive chondrocytes play a significant role in the pathogenesis of OA. Targeting these cells selectively has the potential to mitigate the progression of the disease. Our study provides valuable insights into the intraarticular injection of LNP@FAP siRNA as a promising strategy for the treatment of OA.Graphical abstract

Immunohistochemical Localization of Fibroblast Activation Protein in Coronary Arteries with Different Forms of Atherosclerosis

Background: Fibroblast activation protein (FAP) is a cell surface glycoprotein expressed by myofibroblasts in areas of active tissue remodeling. It plays a potentially important role in cardiac remodeling, atherosclerotic plaque formation, and plaque rupture. Given the distinct pathophysiology and morphology of different forms of atherosclerosis, we analyzed FAP expression in human coronary vessels with no coronary artery disease, atherosclerotic plaques at different levels of progression, and other distinct forms of coronary disease in post bypass vein grafting and cardiac allograft vasculopathy after a heart transplant. Methods: Immunohistochemical staining with monoclonal F19 mouse anti-human FAP antibody was performed to identify FAP in human atherosclerotic plaques, coronary bypass atherosclerosis, and post-transplant arteriosclerosis. The presence and distribution of FAP in different types and stages of human atherosclerosis were compared. Results: There was no FAP staining in patients with no significant coronary disease. All different types of human atherosclerotic lesioning lesions showed the presence of FAP expression, with different staining patterns in advanced atherosclerotic plaque, vein graft atherosclerosis lesions, and arteriosclerosis after a heart transplant. Conclusions: These data suggest that FAP may be a potential diagnostic marker and target for interventions, not only in coronary atherosclerotic plaque, but also in other forms of coronary disease, which have distinct pathophysiologies and currently limited treatment options.

Anti-viral defence by an mRNA ADP-ribosyltransferase that blocks translation.

Host-pathogen conflicts are crucibles of molecular innovation1,2. Selection for immunity to pathogens has driven the evolution of sophisticated immunity mechanisms throughout biology, including in bacterial defence against bacteriophages3. Here we characterize the widely distributed anti-phage defence system CmdTAC, which provides robust defence against infection by the T-even family of phages4. Our results support a model in which CmdC detects infection by sensing viral capsid proteins, ultimately leading to the activation of a toxic ADP-ribosyltransferase effector protein, CmdT. We show that newly synthesized capsid protein triggers dissociation of the chaperone CmdC from the CmdTAC complex, leading to destabilization and degradation of the antitoxin CmdA, with consequent liberation of the CmdT ADP-ribosyltransferase. Notably, CmdT does not target a protein, DNA or structured RNA, the known targets of other ADP-ribosyltransferases. Instead, CmdT modifies the N6 position of adenine in GA dinucleotides within single-stranded RNAs, leading to arrest of mRNA translation and inhibition of viral replication. Our work reveals a novel mechanism of anti-viral defence and a previously unknown but broadly distributed class of ADP-ribosyltransferases that target mRNA.

Slow dissociation kinetics of fentanyls and nitazenes correlates with reduced sensitivity to naloxone reversal at the μ-opioid receptor.

Fentanyls and nitazenes are μ-opioid receptor agonists responsible for a large number of opioid overdose deaths. Here, we determined the potency, dissociation kinetics and antagonism by naloxone at the μ receptor of several fentanyl and nitazene analogues, compared to morphine and DAMGO. In vitro assays of G protein activation and signalling and arrestin recruitment were performed. AtT20 cells expressing μ receptors were loaded with a membrane potential dye and changes in fluorescence used to determine agonist potency, dissociation kinetics and susceptibility to antagonism by naloxone. BRET experiments were undertaken in HEK293T cells expressing μ receptors to assess Gi protein activation and β-arrestin 2 recruitment. The apparent rate of agonist dissociation from the μ receptor varied: morphine, DAMGO, alfentanil and fentanyl dissociated rapidly, whereas isotonitazene, etonitazene, ohmefentanyl and carfentanil dissociated slowly. Slowly dissociating agonists were more resistant to antagonism by naloxone. For carfentanil, the slow apparent rate of dissociation was not because of G protein receptor kinase-mediated arrestin recruitment as its apparent rate of dissociation was not increased by inhibition of G protein-coupled receptor kinases (GRKs) with Compound 101. The in vitro relative potencies of fentanyls and nitazenes compared to morphine were much lower than that previously observed in in vivo experiments. With fentanyls and nitazenes that slowly dissociate from the μ receptor, antagonism by naloxone is pseudo-competitive. In overdoses involving fentanyls and nitazenes, higher doses of naloxone may be required for reversal than those normally used to reverse heroin overdose.

A Rare Case of Orbital Metastasis from Invasive Lobular Carcinoma: Challenges of 18F-FDG PET/CT and the Search for Consensus on Imaging.

Invasive lobular carcinoma (ILC) frequently underlies orbital metastasis. A 74-y-old woman, who was current with mammograms and had no cancer history, presented to her ophthalmologist with visual complaints and was found to have metastatic ILC. MRI was contraindicated, and an 18F-FDG PET/CT scan revealed a mildly hypermetabolic right orbital mass and low uptake in the left subareolar breast, suggestive of metastatic ILC. Small studies have found that in ILC, 16α-18F-fluoroestradiol and fibroblast activation protein inhibitors are more avid than 18F-FDG. There is currently no consensus regarding imaging for ILC. Many people have contraindications to MRI, and the higher rate of false-negative findings on mammography for ILC than for other breast cancers makes this patient population more vulnerable to inaccurate staging, incorrect assessment of tumor burden, and, consequently, insufficient treatment. We provide this interesting case to highlight the potential of 18F-fluoroestradiol PET/CT and fibroblast activation protein inhibitors over 18F-FDG in this breast cancer subtype.

Immunological sub-phenotypes and response to convalescent plasma in COVID-19 induced ARDS: a secondary analysis of the CONFIDENT trial

BackgroundConvalescent plasma (CP) reduced the mortality in COVID-19 induced ARDS (C-ARDS) patients treated in the CONFIDENT trial. As patients are immunologically heterogeneous, we hypothesized that clusters may differ in their treatment responses to CP.MethodsWe measured 20 cytokines, chemokines and cell adhesion markers using a multiplex technique at the time of inclusion in the CONFIDENT trial in patients of centers having accepted to participate in this secondary study. We performed descriptive statistics, unsupervised hierarchical cluster analysis, and examined the association between the clusters and CP effect on day-28 mortality.ResultsOf the 475 patients included in CONFIDENT, 391 (82%) were sampled, and 196/391 (50.1%) had been assigned to CP. We identified four sub-phenotypes representing 89 (22.8%), 178 (45.5%), 38 (9.7%), and 86 (22.0%) patients. The most contributing biomarkers in the principal component analysis were IL-1β, IL-12p70, IL-6, IFN-α, IL-17A, IFN-γ, IL-13, TFN-α, total IgG, and CXCL10. Sub-phenotype-1 displayed a lower immune response, sub-phenotype-2 a higher adaptive response, sub-phenotype-3 the highest innate antiviral, pro and anti-inflammatory response, and adhesion molecule activation, and sub-phenotype-4 a higher pro and anti-inflammatory response, migration protein and adhesion molecule activation. Sub-phenotype-2 and sub-phenotype-4 had higher severity at the time of inclusion. The effect of CP treatment on mortality appeared higher than standard care in each sub-phenotype, without heterogeneity between sub-phenotypes (p = 0.97).ConclusionIn patients with C-ARDS, we identified 4 sub-phenotypes based on their immune response. These sub-phenotypes were associated with different clinical profiles. The response to CP was similar across the 4 sub-phenotypes.Trial registration: Ethics Committee of the University Hospital of Liège CE 2020/239. Clinicaltrials.gov NCT04558476. Registered 2020-09-11, https://www.clinicaltrials.gov/study/NCT04558476.

Fibroblast activation protein inhibitor PET/CT as an emerging diagnostic modality in interstitial lung disease and other fibrotic conditions.

Interstitial lung diseases (ILD) encompass a wide range of disorders characterized by alveolar inflammation and fibrotic tissue remodeling, marked by significant morbidity and mortality. Systemic sclerosis (SSc), among other connective tissue diseases, is a frequent cause of ILD. Assessment of pulmonary fibrosis is frequently constrained by the delayed manifestations of profibrotic activation of fibroblasts, which results in late macroscopic alterations detectable by standard imaging techniques such as computed tomography (CT) and magnetic resonance imaging (MRI) scans. 68Ga-labeled fibroblast activation protein inhibitors (68Ga-FAPI [fibroblast activation protein inhibitor]) are novel radionuclides used in the selective positron emission tomography/computed tomography (PET/CT) detection of profibrotic fibroblasts, a key player in fibrotic tissue remodeling. Application of 68Ga-FAPI in different target organs undergoing fibrosis, such as lung and heart, highlights its efficacy in detecting ongoing fibrotic processes, since FAPI tracer uptake has been correlated with clinical disease progression markers in SSc-ILD. This feature could enable physicians to detect subclinical fibrotic activity and tailor an individualised therapy plan on a case by case basis. The use of 68Ga-FAPI in ILD and other fibrotic conditions may emerge as a novel tool in future clinical practice for both activity monitoring and treatment optimisation. Other tracers tested in ILD of different etiologies have shown promising results and may in future also be considered for potential application in SSc-ILD.

Acylated Anthocyanins From Black Carrots and Their Related Phenolic Acids Diminish Priming and Activation of the NLRP3 Inflammasome in THP-1 Monocytes.

Excessive activation of the nucleotide-binding oligomerization domain-like receptor pyrin domain-containing protein 3 (NLRP3) inflammasome contributes to chronic inflammation. Thus, targeting NLRP3 inflammasome activation by anthocyanins may prevent inflammatory diseases. Therefore, the present study determines the influence of a black carrot extract (BCE) with high amounts of acylated anthocyanins and their related phenolic acids on the NLRP3 inflammasome. THP-1 monocytes are pretreated with a BCE, cyanidin-3-glucoside (C3G), or hydroxycinnamic acids. NLRP3 inflammasome assembly is initiated by priming THP-1 monocytes with lipopolysaccharide and/or activating the NLRP3 inflammasome with nigericin. Flow cytometry is used to assess apoptosis-associated speck-like protein containing a caspase recruitment domain (ASC) speck formation, as well as ASC and NLRP3 protein expression. Caspase-1 activity is measured using a bioluminescent assay, and cytokine concentrations are determined by enzyme-linked immunosorbent assays (ELISA). C3G and phenolic acids diminish ASC and NLRP3 protein expression. In addition, C3G and phenolic acids attenuate ASC speck formation. Furthermore, the BCE and C3G decline caspase-1 activity. Consistently, IL-1β and IL-18 secretion are reduced upon NLRP3 inflammasome activation. The present study shows that a BCE with high amounts of acylated anthocyanins and their related phenolic acids diminish priming and activation of the NLRP3 inflammasome in THP-1 monocytes.

Cryo-electron microscopy reveals a single domain antibody with a unique binding epitope on fibroblast activation protein alpha.

Fibroblast activation protein alpha (FAP) is a serine protease that is expressed at basal levels in benign tissues but is overexpressed in a variety of pathologies, including cancer. Despite this unique expression profile, designing effective diagnostic and therapeutic agents that effectively target this biomarker remain elusive. Here we report the structural characterization of the interaction between a novel single domain antibody (sdAbs), I3, and FAP using cryo-electron microscopy. The reconstructions were determined to a resolution of 2.7 Å and contained two distinct populations; one I3 bound and two I3 molecules bound to the FAP dimer. In both cases, the sdAbs bound a unique epitope that was distinct from the active site of the enzyme. Furthermore, this report describes the rational mutation of specific residues within the complementarity determining region 3 (CDR3) loop to enhance affinity and selectivity of the I3 molecule for FAP. This report represents the first sdAb-FAP structure to be described in the literature.

Molecular Dynamics (MD) Simulations Provide Insights into the Activation Mechanisms of 5-HT2A Receptors

Recent breakthroughs in the determination of atomic resolution 3-D cryo-electron microscopy structures of membrane proteins present an unprecedented opportunity for drug discovery. Structure-based drug discovery utilizing in silico methods enables the study of dynamic connectivity of stable conformations induced by the drug in achieving its effect. With the ever-expanding computational power, simulations of this type reveal protein dynamics in the nano-, micro-, and even millisecond time scales. In the present study, aiming to characterize the protein dynamics of the 5HT2A receptor stimulated by ligands (agonist/antagonist), we performed 1 µs MD simulations on 5HT2A/DOI (agonist), 5HT2A/GSK215083 (antagonist), and 5HT2A (APO, no ligand) systems. The crystal structure of 5HT2A/zotepine (antagonist) (PDB: 6A94) was used to set up the simulation systems in a lipid bilayer environment. We found the monitoring of the ionic lock residue pair (R3.50-E6.30) of 5HT2A in MD simulations to be a good approximation of the effects of agonists (ionic lock breakage) or antagonists (ionic lock formation) on receptor activation. We further performed analyses of the MD trajectories, including Principal Component Analysis (PCA), hydrogen bond, salt bridge, and hydrophobic interaction network analyses, and correlation between residues to identify key elements of receptor activation. Our results suggest that in order to trigger receptor activation, DOI must interact with 5HT2A through residues V5.39, G5.42, S5.43, and S5.46 on TM5, inducing significant conformational changes in the backbone angles of G5.42 and S5.43. DOI also interacted with residues W6.48 (toggle switch) and F6.51 on TM6, causing major conformational shifts in the backbone angles of F6.44 and V6.45. These structural changes were transmitted to the intracellular ends of TM5, TM6, and ICL3, resulting in the breaking of the ionic lock and subsequent G protein activation. The studies could be helpful in future design of selective agonists/antagonists for various serotonin receptors (5HT1A, 5HT2A, 5HT2B, 5HT2C, and 5HT7) involved in detrimental disorders, such as addiction and schizophrenia.

BRAF Modulates the Interplay Between Cell-Cell and Cell-Extracellular Matrix Adhesions in PECAM-1-Mediated Mechanotransduction.

Mechanotransduction, the process of how cells sense and convert mechanical stimuli into biochemical response, is crucial in the migration of leukocytes or cancer cells through the endothelium during inflammation or metastasis. Migrating cells exert forces on the endothelium through cell surface adhesion molecules, such as platelet endothelial adhesion molecule PECAM-1, and this is essential for a successful transmigration. To study PECAM-1-mediated mechanotransduction, we applied PECAM-1-antibody-coated magnetic beads and exerted about 40 pN force on the endothelial monolayer. We show that force increases cell-ECM adhesion in the cell center and is accompanied by the opening of cell-cell junctions. Upon depletion of the MEK/ERK kinase, BRAF force increases cell-ECM adhesion both at the cell periphery and in the cell center, but this does not result in the opening of cell-cell junctions. Decreasing cell-ECM adhesion in BRAF-depleted cells through FAK inhibition results in the remodeling of cell-cell junctions. Force-induced increase in cell-ECM adhesion in the cell center correlates with the activation of the transcriptional cofactor Yes-associated protein (YAP). Furthermore, the induced activation of YAP through LATS inhibition prevents junctional remodeling in control cells. Thus, the activation of YAP might determine the strength of cell-cell junctions during PECAM-1-mediated mechanotransduction.

Comment on: Fibroblast activation protein inhibitor-positron emission tomography in aortitis: fibroblast pathology in active inflammation and remission.

Comment on: Fibroblast activation protein inhibitor-positron emission tomography in aortitis: fibroblast pathology in active inflammation and remission.

P02.07.B FIBROBLAST ACTIVATION PROTEIN EXPRESSING MESENCHYMAL CELLS INFLUENCE T CELL ABUNDANCE AND FUNCTION IN GLIOBLASTOMA

Abstract BACKGROUND Glioblastomas (GBMs) are aggressive brain tumors with strong immunosuppressive properties. In epithelial cancers, mesenchymal cells expressing fibroblast activation protein (FAP) play an important role in modulating the T cell response. We have recently shown that FAP+ mesenchymal cells are present in human GBMs. The aim of this study was to determine their effect on T cell abundance and function. MATERIAL AND METHODS GBM tumors (16 samples) were mechanically and enzymatically dissociated and analyzed for immune cell subpopulations by flow cytometry. Expression of T cell related genes was analyzed by qRT-PCR in GBMs selected based on FAP protein concentration determined by ELISA (14 FAP high [upper tercile], 16 FAP low [lower tercile]). Immunohistochemistry (IHC) was used to compare the number of CD3+, CD4+, and CD8+ T cells in GBMs with high (upper tercile, n=21) and low abundance of FAP+ stroma (lower tercile, n=20). Co-localization of FAP+ mesenchymal cells and CD3, PD-L1 and PD-L2 was evaluated by immunofluorescence in frozen sections. 8 FAP+ mesenchymal and 3 glioblastoma stem-like cell cultures were derived from human GBMs and PD-L1 and PD-L2 expression was determined using ELISA. Peripheral blood mononuclear cells were isolated from healthy donors´ buffy coats. Proliferation of stimulated T cells in conditioned media from FAP+ mesenchymal cells was analyzed by flow cytometry. RESULTS The percentage of T cells in CD45+ cells from GBMs positively correlated with FAP expression. Expression of the T cell inhibitory molecule PD-L2 was higher in FAP high GBMs. Immunohistochemisty revealed that the numbers of CD3+ and CD8+ T cells were higher in GMBs with a high abundance of FAP+ stroma and T cells were frequently in close proximity to FAP+ mesenchymal cells, which were often PD-L2 positive. In vitro, FAP+ mesenchymal cells expressed more PD-L2 than glioblastoma stem-like cells. T cell proliferation was decreased after exposure to conditioned media from FAP+ mesenchymal cells. CONCLUSION FAP+ mesenchymal cells influence T cell abundance in GBMs and may affect T cell functions by limiting their proliferation via soluble factors or cell-cell contact. Acknowledgment: This work was supported by the National Institute for Cancer Research (LX22NPO5102), the Center for Tumor Ecology (CZ.02.1.01/0.0/0.0/16_019/0000785), Charles University project GAUK 365022 and Cooperatio Program Oncology and Haematology“.

Vitis vinifera Lipoxygenase LoxA is an Allosteric Dimer Activated by Lipidic Surfaces

Lipoxygenases catalyze the peroxidation of poly-unsaturated fatty acid chains either free or esterified in membrane lipids. Vitis vinifera LoxA is transcriptionally induced at ripening onset and localizes at the inner chloroplastic membrane where it is responsible for galactolipid regiospecific mono- and di-peroxidation. Here we present a kinetic and structural characterization of LoxA. Our X-ray structures reveal a constitutive dimer with detergent induced conformational changes affecting substrate binding and catalysis. In a closed conformation, a LID domain prevents substrate access to the catalytic site by steric hindrance. Detergent addition above the CMC destabilizes the LID and opens the dimer with both catalytic sites accessible from the same surface framed by the PLAT domains. As a consequence, detergent molecules occupy allosteric sites in the PLAT/catalytic domain interfaces. These structural changes are mirrored by increased enzymatic activity and positive cooperativity when the substrate is provided in micelles. The ability to interact with micelles is lost upon dimer destabilization by site-directed mutagenesis as assessed by tryptophan fluorescence. Our data allow to propose a model for protein activation at the membrane, classifying LoxA as an interfacial enzyme acting on fatty acid chains directly from the membrane similar to mammalian 15-LOX and 5-LOX.

Neuropeptide signalling orchestrates T cell differentiation.

The balance between T helper type 1 (TH1) cells and other TH cells is critical for antiviral and anti-tumour responses1-3, but how this balance is achieved remains poorly understood. Here we dissected the dynamic regulation of TH1 cell differentiation during in vitro polarization, and during in vivo differentiation after acute viral infection. We identified regulators modulating T helper cell differentiation using a unique TH1-TH2 cell dichotomous culture system and systematically validated their regulatory functions through multiple in vitro and in vivo CRISPR screens. We found that RAMP3, a component of the receptor for the neuropeptide CGRP (calcitonin gene-related peptide), has a cell-intrinsic role in TH1 cell fate determination. Extracellular CGRP signalling through the receptor RAMP3-CALCRL restricted the differentiation of TH2 cells, but promoted TH1 cell differentiation through the activation of downstream cAMP response element-binding protein (CREB) and activating transcription factor 3 (ATF3). ATF3 promoted TH1 cell differentiation by inducing the expression of Stat1, a key regulator of TH1 cell differentiation. After viral infection, an interaction between CGRP produced by neurons and RAMP3 expressed on T cells enhanced the anti-viral IFNγ-producing TH1 and CD8+ T cell response, and timely control of acute viral infection. Our research identifies a neuroimmune circuit in which neurons participate in T cell fate determination by producing the neuropeptide CGRP during acute viral infection, which acts on RAMP3-expressing T cells to induce an effective anti-viral TH1 cell response.

The Nedd4L ubiquitin ligase is activated by FCHO2-generated membrane curvature.

The C2-WW-HECT domain ubiquitin ligase Nedd4L regulates membrane sorting during endocytosis through the ubiquitination of cargo molecules such as the epithelial sodium channel (ENaC). Nedd4L is catalytically autoinhibited by an intramolecular interaction between its C2 and HECT domains, but the protein's activation mechanism is poorly understood. Here, we show that Nedd4L activation is linked to membrane shape by FCHO2, a Bin-Amphiphysin-Rsv (BAR) domain protein that regulates endocytosis. FCHO2 was required for the Nedd4L-mediated ubiquitination and endocytosis of ENaC, with Nedd4L co-localizing with FCHO2 at clathrin-coated pits. In cells, Nedd4L was specifically recruited to, and activated by, the FCHO2 BAR domain. Furthermore, we reconstituted FCHO2-induced recruitment and activation of Nedd4L in vitro. Both the recruitment and activation were mediated by membrane curvature rather than protein-protein interactions. The Nedd4L C2 domain recognized a specific degree of membrane curvature that was generated by the FCHO2 BAR domain, with this curvature directly activating Nedd4L by relieving its autoinhibition. Thus, we show for the first time a specific function (i.e., recruitment and activation of an enzyme regulating cargo sorting) of membrane curvature by a BAR domain protein.

Negative 18F-FDG and Positive 68Ga-FAPI-04 Findings in a Patient With Acute Exacerbation of Chronic Cholecystitis.

Acute cholecystitis typically exhibits intense FDG uptake of the gallbladder wall. Radiolabeled fibroblast activation protein inhibitor (FAPI) is considered as a potential alternative agent for tumor-specific imaging. We report 18F-FDG and 68Ga-FAPI-04 PET/MR findings in a 44-year-old woman with acute exacerbation of chronic cholecystitis. The lesions show negative 18F-FDG uptake but intense 68Ga-FAPI-04 uptake in PET/MR. This case highlights the imperative for nuclear medicine clinicians to exercise vigilance when evaluating gallbladder lesions exhibiting intense 68Ga-FAPI-04 but negative 18F-FDG uptake.

Cadmium Induces Vascular Endothelial Cell Detachment by Downregulating Claudin-5 and ZO-1 Levels.

Cadmium is a contributing factor to cardiovascular diseases and highly toxic to vascular endothelial cells. It has a distinct mode of injury, causing the de-endothelialization of regions in the monolayer structure of endothelial cells in a concentration-dependent manner. However, the specific molecules involved in the cadmium toxicity of endothelial cells remain unclear. The purpose of this study was to identify the specific molecular mechanisms through which cadmium affects endothelial detachment. Cadmium inhibited the expression of claudin-5 and zonula occludens (ZO)-1, which are components of tight junctions (strongest contributors to intercellular adhesion), in a concentration- and time-dependent manner. Compared to arsenite, zinc, and manganese, only cadmium suppressed the expression of both claudin-5 and ZO-1 molecules. Moreover, the knockdown of claudin-5 and ZO-1 exacerbated cadmium-induced endothelial cell injury and expansion of the detachment area, whereas their overexpression reversed these effects. CRE-binding protein inhibition reduced cadmium toxicity, suggesting that CRE-binding protein activation is involved in the cadmium-induced inhibition of claudin-5 and ZO-1 expression and endothelial detachment. These findings provide new insights into the toxicological mechanisms of cadmium-induced endothelial injury and risk of cardiovascular disease.

N-butanol extract of Broussonetia papyrifera (L.) L′Hér. ex Vent root bark alleviates atopic dermatitis by targeting E3 ubiquitin ligase WWP1 to promote NLRP3 degradation

BackgroundBroussonetia papyrifera (L.) L′Hér. ex Vent (B. papyrifera) is a deciduous tree widely distributed in Asia. Previous studies have revealed that leaves of B. papyrifera ameliorated atopic dermatitis (AD)-like symptoms and inflammatory response. However, the impact and underlying mechanism of other parts of B. papyrifera on AD remain elusive. MethodsThe AD mice induced by 1-Chloro-2,4-dinitrochlorobenzene were used to observe the histopathological alterations in the skin tissues using hematoxylin-eosin staining and toluidine blue staining techniques. Serum levels of inflammatory factors were quantified utilizing ELISA. Pyroptosis was analyzed by lactate dehydrogenase release and flow cytometry in human keratinocytes. The activation of Nod-like receptor protein 3 (NLRP3) inflammasome was analyzed by western blots. Furthermore, the mechanism underlying the inhibition of NLRP3 inflammasome by N-butanol extracts of B. papyrifera root bark (NE-BPRB) was investigated using cellular thermal shift assay and surface plasmon resonance techniques. ResultsTreatment with NE-BPRB significantly ameliorated symptoms of AD mice and reduced serum levels of pro-inflammatory factors. NE-BPRB intervention exhibited inhibitory effects on NLRP3 inflammasome activation and pyroptosis in vitro and in vivo. NE-BPRB and its primary bioactive constituent chlorogenic acid (CA) promote the K48-linked ubiquitination of NLRP3, leading to its proteasomal degradation by binding WW domain containing E3 ubiquitin protein ligase 1 (WWP1). ConclusionsThe NE-BPRB and its primary bioactive constituent, CA, effectively inhibit the formation of the NLRP3 inflammasome and impede cell pyroptosis by promoting K48-linked ubiquitin-dependent proteasomal degradation of NLRP3 through binding to the E3 ubiquitin ligase WWP1, thereby resulting in improved AD.

Conformal immunomodulatory hydrogels for the treatment of otitis media

Otitis media (OM), a condition stemming from the proliferation of various bacteria within the tympanic cavity (TC), is commonly addressed through the administration of ofloxacin (OFL), a fluoroquinolone antibiotic. Nevertheless, the escalating issue of antibiotic resistance and the challenge of drug leakage underscore the exploration of an alternative, more effective treatment modality in clinical practice. Here, we introduce a simple and easily implementable fluid-regulated strategy aimed at delivering immunomodulatory hydrogels into the TC, ensuring conformal contact with the irregular anatomical surfaces of the middle ear cavity to more effectively eliminate bacteria and treat OM. This innovative strategy exhibits expedited therapeutic process of antibiotic-resistant, acute and chronic OM rats, and significant reductions in the severity of tympanic membrane (TM) inflammation, residual bacteria within the TC (0.12 *105 CFU), and the thickness of TM/TC mucosa (17.63/32.43 μm), as compared to conventional OFL treatment (3.6, 0.76 *105 CFU, 48.70/151.26 μm). The broad-spectrum antibacterial and antibiofilm properties of this strategy against a spectrum of OM pathogens are demonstrated. The strategy is validated to bolster the host’s innate immune response through the stimulation of antibacterial protein synthesis, macrophage proliferation and activation, thereby accelerating bacterial eradication and inflammation resolution within the TC. This facile, cost-effective and in vivo degradable technology exhibits promising prospects for future clinical implementation.