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Expansion microscopy (ExM) has enabled nanoscale imaging of tissues by physically enlarging biological samples in a swellable hydrogel. However, the increased sample size and water-based environment pose challenges for deep imaging using conventional inverted confocal microscopes, particularly due to the limited working distance of high-numerical-aperture (NA) water immersion objectives. Here, we introduce a practical imaging alternative that utilizes an inverted water-dipping objective and a refractive-index-matched optical path using fluorinated ethylene propylene (FEP) film. Through point spread function (PSF) measurements and simulations, we show that the FEP film introduces predominantly defocus-like wavefront profiles characteristic of high NA systems, which result in an easily correctable axial shift of the focal plane. To ensure stable immersion and refractive index continuity, we use an arrangement relying on an FEP film, Immersol W, water and a FEP-based imaging dish. This configuration achieves sub-micron lateral and axial resolution, supports large tile-scan acquisitions, and maintains image quality across depths exceeding 800 µm. We validate the system by imaging 4×-expanded U2OS cells and human cerebral organoids. Our approach provides a low-cost, plug-and-play solution for high-resolution volumetric imaging of expanded samples using standard inverted microscopes.

Cis-regulatory elements (CREs) are noncoding DNA regions regulating cell-type-specific gene expression programs by interacting with distal gene promoters. Here, we aim to decode the function and spatial organization of CRE-promoter interactions in human cardiomyocytes. We analyzed the epigenome and chromatin interactions of human male atrial, ventricular, and failing cardiomyocytes. Atrial and ventricular cardiomyocytes harbored chamber-specific CRE-promoter interactions modulating gene expression as confirmed by functional epigenetic silencing. These CRE-promoter interactions explain the distinct contribution of non-coding genetic variants to atrial and ventricular diseases, such as dilated cardiomyopathy and arrhythmias. We dissected the prototypic KCNJ2 locus, encoding a potassium channel associated with ventricular arrhythmia susceptibility. Functional epigenetic silencing confirmed that CREs, harboring QT-duration-associated genetic risk factors, modulate KCNJ2 gene expression levels, alter KCNJ2-dependent channel currents, and affect cardiomyocyte repolarization. The presented human CM-specific chromatin interaction analysis provides key insights into regulatory mechanisms and aids in interpreting genetic risk factors. Here the authors functionally test and resolve the spatial genome organization of cis-regulatory elements and genetic variants in atrial, ventricular, and failing human cardiomyocytes and linked them to heart disease traits, including QT syndrome.

Chronic neuroinflammation plays a key role in the progression of Alzheimer’s disease (AD), and the cytosolic calcium-dependent phospholipase A2 (cPLA2) enzyme is a critical mediator of inflammatory lipid signaling pathways. Here we investigate the therapeutic potential of novel cPLA2 inhibitors in modulating neuroinflammation in AD. By leveraging the giga-scale V-SYNTHES2 virtual screening in on-demand chemical space and conducting two rounds of optimization for potency and selectivity, we have identified BRI-50460, achieving an IC50 of 0.88 nM in cellular assays that measure cPLA2-mediated arachidonic acid release. In vivo studies revealed favorable brain-to-plasma ratios, highlighting the ability of BRI-50460 to penetrate the central nervous system, modulating neuroinflammatory pathways, and restoring lipid homeostasis. In astrocytes and neurons derived from human induced pluripotent stem cells, BRI-50460 mitigates the effects of amyloid beta 42 oligomers on cPLA2 activation, tau hyperphosphorylation, and synaptic loss. Our results support that small molecule inhibitors of cPLA2 can modulate the downstream inflammatory signaling, offering a promising therapeutic strategy for neurodegenerative diseases.

Interleukin-17 (IL-17) plays a central role in the pathogenesis of various autoimmune diseases. Soluble CD14 (sCD14), a marker of innate immune activation, is elevated in several inflammatory conditions. However, its influence on IL-17 production and the differentiation of Th17 cells remains poorly understood. We found that sCD14 enhances Th17-associated cytokine production and up-regulates critical transcription factors such as STAT3 and RORC. Notably, sCD14's effect on Th17 polarization was mediated indirectly through autologous sCD14-treated peripheral blood mononuclear cell (PBMC) supernatant (sCD14-PBMC-Sup). Additionally, we identified a distinct cytokine profile enriched for pro-inflammatory cytokines and chemokines in sCD14-treated T cells, further reinforcing the Th17-promoting role of sCD14. Interestingly, gamma-aminobutyric acid (GABA), a metabolite elevated in sCD14-treated monocytes, was identified as a potential contributor to Th17 polarization. GABA supplementation in T-cell cultures enhanced IL-17A secretion, indicating its role as a signaling molecule in T-cell differentiation. Our findings also revealed the expansion of innate lymphoid cell (ILC)2/3-like cells in T-cell cultures exposed to sCD14-PBMC-Sup and GABA, highlighting the potential role of monocytes in Th17-mediated immunity. Furthermore, while sCD14 promoted Th17 polarization, it simultaneously impaired T-cell activation and proliferation, suggesting an immunosuppressive effect mediated by soluble factors released from monocytes. These results underscore the dual role of sCD14 in modulating T-cell responses, promoting Th17 differentiation while suppressing T-cell effector functions. This study identifies a previously unrecognized role for sCD14 in promoting Th17 induction, highlighting its contribution to immune regulation and its potential as a therapeutic target in Th17-driven autoimmune conditions.

HIV-associated distal sensory polyneuropathy (HIV-DSP) remains prevalent even in the antiretroviral therapy (ART) era. Previously, we identified the upregulation of nociceptive ion channels transient receptor potential vanilloid 1 (TRPV1) and ankyrin 1 (TRPA1) in the dorsal root ganglia (DRG) of simian immunodeficiency virus (SIV)-infected ART-treated macaques. To investigate upstream mechanisms, we performed bulk RNA-seq and pathway analysis on DRGs from uninfected, SIV-infected, and SIV-infected/ART macaques. SIV infection drove strong activation of upstream regulators of interferon γ (IFNγ) and lipopolysaccharide (LPS). Although ART reduced overall IFNγ and LPS pathway activity, the IFNγ-inducible chemokines C-X-C motif chemokine ligand (CXCL)9 and CXCL10 remained significantly upregulated. To determine whether these chemokines influence TRPV1/TRPA1 expression, we treated induced pluripotent stem cell-derived peripheral sensory neurons (iPSC-PSNs) with CXCL9 and CXCL10, which induced a significant increase in TRPV1 but not TRPA1 expression. In parallel experiments, IFNγ but not LPS stimulated monocyte-derived macrophages (MDMs) to release CXCL9 and CXCL10. Conditioned media from IFNγ-treated MDMs modestly increased TRPV1 expression in iPSC-PSNs, and pharmacological inhibition of CXCR3, the receptor of CXCL9/10, did not reduce this effect. Together, these data indicate that persistent IFNγ-driven CXCL9/10 signaling may be one contributor to nociceptor sensitization underlying HIV-DSP, even in the presence of ART.

Human induced pluripotent stem cells (hiPSCs) offer significant potential for differentiation and research applications in cardiovascular diseases. When induced differentiated hiPSC-derived cardiomyocytes (hiPSC-CMs) are transplanted into the infarcted myocardial region, they exhibit extremely low survival rates and unsatisfactory therapeutic effects due to ischemia, hypoxia, and immune inflammation in the surrounding environment. To address this issue, we used Panax notoginseng saponin R1 (NGR1), which has demonstrated significant protective effects in prior research, to pretreat hiPSC-CMs before transplantation. Utilizing an in vitro H2O2 oxidative stress model and a nude mouse myocardial infarction (MI) model, we investigated the mechanism through which NGR1 pretreatment enhances the therapeutic efficacy of hiPSC-CM transplantation. The results revealed that the hiPSC-CMs expressed cTnT. NGR1 did not promote the proliferation of hiPSC-CMs but instead induced elevated levels of p-Akt protein in these cells. Compared to hiPSC-CM transplantation alone, transplantation of hiPSC-CMs pretreated with NGR1 exhibited higher ejection fraction (EF) and fractional shortening (FS) values, along with reduced infarct size and collagen deposition. Additionally, there were more HNA-positive cardiomyocytes in the cardiac tissue, fewer TUNEL-positive signals, and increased VWF-positive and Lyve1-positive signals. Furthermore, the gene expression levels of VEGFC, IGF-1, and SDF-1 were higher. Therefore, NGR1 pretreatment improves the survival of transplanted hiPSC-CMs in tissues, reduces myocardial apoptosis, enhances cardiac function, decreases infarct size and collagen deposition, promotes angiogenesis and lymphangiogenesis, and stimulates paracrine secretion.

The Mas-related G protein-coupled receptor (MRGPR) X2 is expressed on skin mast cells and can be stimulated by an unusually broad spectrum of ligands, including specific drugs and even endogenous peptides. MRGPRX2 activation can induce mast cell degranulation and consequently mediator release, leading to inflammatory and hypersensitivity reactions. In addition, MRGPRX2 mediates pain and itching sensations, leading to increased efforts to identify MRGPRX2 inhibitors, including plant-derived compounds. Components within oat extracts have been shown to mediate anti-inflammatory and itch-relieving properties, but a possible inhibitory effect on MRGPRX2 activation has not yet been investigated. We aimed to fill this gap and explored whether an oat kernel extract can modulate MRGPRX2 activation. For this purpose, we established a mast cell model with the human LAD2 cell line and used it to investigate the consequences of exposure to oat extract. While we did not observe any influence on cell viability, we analyzed the impact of oat extract on MRGPRX2-mediated mast cell activation and degranulation initiated by the three confirmed MRGPRX2 ligands c48/80, substance P, and cortistatin 14. Exposure to oat extract resulted in a significant reduction in mast cell degranulation for all three ligands, as assessed by the release of β-hexosaminidase, tryptase, cell surface expression of CD63 and CD107a, and phosphorylation of ERK. All results were confirmed with primary human mast cells. Thus, we demonstrated for the first time that oat extract leads to a significant reduction in MRGPRX2 activation, pointing to a previously unrecognized capacity of natural compounds to modulate this pathway.