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Parechovirus ahumpari 3 (HPeV-3) is among the main agents causing severe neonatal neurological infections such as encephalitis and meningitis. However, the underlying molecular mechanisms and changes to the host cellular landscape leading to neurological disease has been understudied. Through quantitative proteomic analysis of HPeV-3 infected neural organoids, we identified unique metabolic changes following HPeV-3 infection that indicate immunometabolic dysregulation. Protein and pathway analyses showed significant alterations in neurotransmission and potentially, neuronal excitotoxicity. Elevated levels of extracellular glutamate, lactate dehydrogenase (LDH), and neurofilament light (NfL) confirmed glutamate excitotoxicity to be a key mechanism contributing to neuronal toxicity in HPeV-3 infection and can lead to apoptosis induced by caspase signaling. These insights are pivotal in delineating the metabolic landscape following severe HPeV-3 CNS infection and may identify potential host targets for therapeutic interventions.

Regulatory T cells are a class of T lymphocytes which respond to activation signals by expanding their cell numbers, and whose culturing and expansion are of significant clinical interest. Cellular activation states are used to inform process control decisions such as restimulation and can be probed with experimental measurements of cell surface markers. However, these measurements are expensive, time-consuming, and invasive, and an urgent need exists for devising a non-invasive method for activation state monitoring that could be deployed on-line. Raman spectroscopy is a label-free and information-rich optical method that, when coupled to data analytical methods, can ameliorate these experimental issues. In this work, we quantitatively estimated experimental measurements of regulatory T cell activation markers with high accuracy. We simulated a clinical manufacturing setting by building an L1-regularized least-squares model with spectroscopic data from six regulatory T cell donors. Then, we validated the constructed model by accurately estimating different experimental measurements of biomarker values from two external donors, unseen by the model. We have devised a robust program to effectively estimate the activation state of regulatory T cells. We anticipate our method to be used with on-line Raman probes integrated into cell manufacturing devices for label-free monitoring of these processes.

DNA repair mechanisms in human primary cells, including error-free repair, and, recurrent nuclease cleavage events, remain largely uncharacterised. We elucidate gene-editing related repair processes using Cleavage and Lesion Evaluation via Absolute Real-time dPCR (CLEAR-time dPCR), an ensemble of multiplexed dPCR assays that quantifies genome integrity at targeted sites. Utilising CLEAR-time dPCR we track active DSBs, small indels, large deletions, and other aberrations in absolute terms in clinically relevant edited cells, including HSPCs, iPSCs, and T-cells. By quantifying up to 90% of loci with unresolved DSBs, CLEAR-time dPCR reveals biases inherent to conventional mutation screening assays. Furthermore, we accurately quantify DNA repair precision, revealing prevalent scarless repair after blunt and staggered end DSBs and recurrent nucleases cleavage. This work provides one of the most precise analyses of DNA repair and mutation dynamics, paving the way for mechanistic studies to advance gene therapy, designer editors, and small molecule discovery. Quantifying genomic aberrations resulting from designer nucleases activity is essential for gene therapy clinical translation. Here, the authors present a modular digital PCR technique that profiles DNA repair precision and cut-repair cycles at the edited loci, exposing current evaluation biases.

We used high-resolution optical mapping (~50 µm) to investigate potential arrhythmia mechanisms following transplantation of engineered cardiac tissue. We induced myocardial infarction in 6 immunosuppressed pigs and implanted cardiac spheroids into the border zone. One week later, 600-µm-thick cardiac slices containing implanted spheroids were harvested and electrical propagation was imaged. Histology showed low connexin-43 expression, scar, and misaligned muscle fibers at the graft-host interface. We observed propagation from host-to-graft in 10 slices from 3 pigs. Host-graft electrical bridges were spaced by millimeters. Propagation was ~4-fold slower in the graft than host. One graft beat spontaneously, but activation did not propagate from graft-to-host in this, or any other slice. We did not observe reentry, but slow in-graft conduction and sparse electrical bridges provided opportunity for reentry induction. These data reveal potential for reentrant or focal arrhythmias 1 week post-implant, which may resolve with maturation of the graft and the graft-host interface.

USH2A mutations are the leading cause of autosomal recessive retinitis pigmentosa (RP), a progressive blinding disease marked by photoreceptor degeneration. Animal models fail to recapitulate the features of USH2A RP seen in humans, and its earliest pathogenic events remain unknown. Here, we established a human model of USH2A RP using retinal organoids derived from patient induced pluripotent stem cells and CRISPR-Cas9-engineered isogenic-USH2A−/− induced pluripotent stem cells. Methods: We assessed organoids for cellular, molecular, and morphological defects using serial live imaging and whole organoid and fixed section analyses. Results: Both patient-derived and isogenic-USH2A−/− organoids showed preferential rod photoreceptor loss followed by widespread degeneration, consistent with the clinical phenotype. Additionally, isogenic-USH2A−/− organoids showed early defects in proliferation and structure. Conclusions: Our findings suggest that molecular changes precede overt photoreceptor loss in USH2A RP, and pathogenesis may begin before clinical symptoms emerge. By defining early and late disease features, we provide new insight on the developmental origins of USH2A RP to guide therapeutic strategies.

The selective peroxisome proliferator–activated receptor delta (PPARD) agonist seladelpar reduces liver injury and modulates bile acid metabolism in preclinical models. Seladelpar was recently approved for the secondary treatment of primary biliary cholangitis (PBC). Despite its beneficial effects for liver diseases, the target cells of seladelpar on a single-cell level remain unknown. This study is aimed at investigating the effect of seladelpar on single liver cells. Methods and Results: CD-1 mice were gavaged with vehicle or seladelpar (10 mg/kg body weight), and the liver was harvested 6 h later. Single-nuclei RNA sequencing (snRNA-seq) analysis showed the engagement of PPARD target genes primarily in hepatocytes and cholangiocytes by seladelpar. The top two upregulated genes, Ehhadh and Cyp4a14, are related to fatty acid metabolism and were increased in hepatocytes, cholangiocytes, and Kupffer cells. Abcb4, an important canalicular transporter with hepatoprotective effects, was significantly upregulated in hepatocytes. We confirmed upregulated Abcb4 gene expression in seladelpar-treated primary mouse hepatocytes isolated from C57BL/6 mice. We further incubated nonparenchymal liver cells with seladelpar. Although there was a significant increase in the PPARD-responsive genes Pdk4 and Angptl4 in cholangiocytes, Kupffer cells, and hepatic stellate cells, seladelpar did not exert specific liver-protective effects in these cell types. Conclusions: The selective PPARD agonist seladelpar induced PPARD-responsive genes primarily in hepatocytes and cholangiocytes. Seladelpar upregulated Abcb4 in hepatocytes, which might contribute to its beneficial effects in cholestatic liver disorders.

BackgroundThe cycling intestinal stem cells (ISCs) exhibit radiosensitivity, and their death or impaired regenerative capacity following irradiation may result in intestinal barrier dysfunction. The cystathionine-β-synthase (CBS)/H2S axis plays a critical role in regulating cell proliferation, reactive oxygen species scavenging, and the DNA damage response. However, it remains unclear whether the CBS/H2S axis modulates ISC homeostasis and tissue radiosensitivity. Methods: Intestinal epithelium specific conditional CBS knockout mice were generated by crossing CBSfl/+ mice with Villin-CreERT2 mice. CAGGCre-ER™ mice were crossed with CBSfl/fl mice to achieve CBS knockout in multiple tissues and cell types. The Lgr5-Tdtaomato-Flag mice were generated by CRISPR/Cas9 system. The CBS inhibitor AOAA or the H2S donor GYY4137 was used to treat mice or intestinal crypt organoids. Hematoxylin and eosin, immunohistochemistry, immunofluorescence, Western blot, qRT-PCR, et al. were employed to investigate the role of the CBS/H2S axis in ISCs homeostasis and radiation-induced intestinal damage. Results: Lgr5 + ISCs and progenitor cells expressed higher levels of CBS than differentiated cells. The cecum and colon expressed significant higher CBS levels than the small intestine. Treatment with the H2S donor GYY4137 enhanced the proliferation of intestinal organoids in vitro, while inhibition of CBS by AOAA reduced this effect. Genetic knockout of CBS in the intestinal epithelium or global downregulation of CBS driven by CAGG-CreER™ in vivo did not affect ISC proliferation or differentiation under physiological conditions. Pharmacological regulation of the CBS/H2S axis in vitro failed to protect organoids from radiation-induced damage. Interestingly, administration of AOAA in vivo reduced radiation-induced atrophy of the intestinal mucosa. Furthermore, global downregulation of CBS significantly promoted ISC recovery after irradiation exposure. However, intestinal epithelium-specific CBS knockout did not confer radioprotective effects. Conclusions: Our findings suggest that the CBS/H2S axis contributes to the regulation of ISC homeostasis and represents a potential target for radiation protection, mediated through the intervention of non-epithelial cells.

The high burden of dilated cardiomyopathy (DCM) in individuals of African descent remains incompletely explained. Here, to explore a genetic basis, we conducted a genome-wide association study in 1,802 DCM cases and 93,804 controls of African genetic ancestry (AFR). A nonsense variant (rs3211938:G) in CD36 was associated with increased risk of DCM. This variant, believed to be under positive selection due to a protective role in malaria resistance, is present in 17% of AFR individuals but <0.1% of European genetic ancestry (EUR) individuals. Homozygotes for the risk allele, who comprise ~1% of the AFR population, had approximately threefold higher odds of DCM. Among those without clinical cardiomyopathy, homozygotes exhibited an 8% absolute reduction in left ventricular ejection fraction. In AFR, the DCM population attributable fraction for the CD36 variant was 8.1%. This single variant accounted for approximately 20% of the excess DCM risk in individuals of AFR compared to those of EUR. Experiments in human induced pluripotent stem cell-derived cardiomyocytes demonstrated that CD36 loss of function impairs fatty acid uptake and disrupts cardiac metabolism and contractility. These findings implicate CD36 loss of function and suboptimal myocardial energetics as a prevalent cause of DCM in individuals of African descent. Genome-wide analysis in individuals of African ancestry identifies a nonsense variant in CD36 associated with increased risk of dilated cardiomyopathy (DCM), partly accounting for the higher incidence of DCM in African-ancestry populations.