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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.

Radiotherapy is a standard treatment of pediatric brain tumors. Though the survival rate has improved for many tumor types, most patients suffer long-term cognitive decline and there is currently no way of preventing radiation-induced damage to healthy brain tissue. Here, we used a human forebrain organoid model to investigate if the α2-adrenoceptor and I1-imidazoline receptor agonist clonidine could prevent radiotoxicity. We found that treatment of organoids with clonidine significantly reduced radiation-induced loss of neural progenitor cells, neurons, astrocytes, and oligodendrocyte lineage cells. Moreover, clonidine reduced overall DNA damage and signs of reactive gliosis in organoids. Our findings demonstrate that pharmacological rescue of radiation neurotoxicity is possible in a human brain organoid model and provides a rationale for future drug repurposing studies aiming to prevent radiation-induced brain injury in children treated with radiotherapy.

Chronic compressive cervical spinal cord injury (cCSCI), a debilitating condition, lacks effective treatment options. Addressing this gap, our study introduces a novel rat model of cCSCI developed through spinal cord compression via synthetic polyether sheet implantation, closely mimicking human pathology. We evaluated the model’s fidelity utilizing a comprehensive series of behavioral, electrophysiological, and histological assessments. Our research also explored the therapeutic potential of oligodendrogenic neural progenitor cells (oNPCs) derived from induced pluripotent stem cells. Transplanted oNPCs successfully integrated into the host spinal cord, differentiated into neurons, astrocytes, and oligodendrocytes, and demonstrated a remarkable capacity for enhancing neuroplasticity. Electrophysiological analyses revealed significant improvements in motor evoked potentials and a rectification of the excitability imbalance posttransplantation, indicating substantial recovery of motor circuits. Histological findings complemented these results, showing enhanced remyelination and a reduction in excitatory transmitter expression in the residual gray matter. Functionally, the transplantation of oNPCs led to marked improvements in grip strength, locomotor abilities, and sensory functions, surpassing those seen with standard treatments. This study not only provides a novel and reliable rat model of cCSCI for further research but also highlights the potential of oNPCs as a transformative approach for spinal cord injury therapy, suggesting their significant role in neural regeneration and repair.

Acute myeloid leukemia (AML) is a genetically heterogeneous malignancy characterized by the clonal proliferation of undifferentiated myeloid precursors in the bone marrow. Although standard induction regimens based on anthracyclines often achieve initial remission, up to 25% of patients exhibit primary refractory disease and nearly 50% relapse, underscoring the urgent need to overcome therapy resistance. Aldehyde dehydrogenase 1 (ALDH1) contributes to leukemic cell survival by maintaining stemness, proliferation, and chemoresistance through aldehyde detoxification and retinoic acid synthesis. Here, we identify two enhancer elements, ALDH1A1‐E3 and ALDH1A2‐E1‐A, that mediate transcriptional activation of ALDH1A1 and ALDH1A2 in response to the anthracycline daunorubicin. These enhancers are regulated by STAT3 and FOS/JUN transcription factors, which cooperatively link drug response to ALDH1 induction. Functional validation in AML cell lines, primary samples, and xenograft models shows that ALDH1 upregulation is part of an adaptive stress response and may contribute to reduced anthracycline sensitivity. Co‐treatment with the ALDH1A1/1A2 inhibitor DIMATE synergistically enhances daunorubicin efficacy across in vitro and in vivo resistant models. Consistently, high ALDH1 expression is associated with adverse genetic risk, prior anthracycline exposure, and inferior OS, particularly in relapsed/refractory AML. These findings uncover a novel enhancer‐mediated mechanism of ALDH1 induction in the context of anthracycline exposure and support the rationale for future clinical trials combining standard treatments with ALDH1‐targeted approaches, including the clinical‐stage inhibitor DIMATE.

Management of chronic kidney disease (CKD) remains a major challenge due limited therapeutic options to reverse fibrosis, which is a critical feature in CKD. Partial epithelial-to-mesenchymal transition (EMT) of tubular epithelial cells (TECs) is a key driver of fibrosis, and has become an important focus for kidney protection strategies. Blood platelets, a major source of circulating transforming growth factor beta (TGF-β), are implicated in pathogenesis of CKD, but their involvement in EMT and kidney fibrosis remains uncertain. Methods: We used two mouse models of renal fibrosis—diabetic kidney disease (DKD) and unilateral ureter obstruction (UUO)—to examine the connection between platelets, partial EMT, and fibrosis. Platelet inhibition or depletion was performed to assess EMT, cell cycle arrest, and fibrosis. In vitro, platelets were applied to TECs and kidney organoids. To determine the role of TGF-β signaling, we used TGF-βRI inhibitor. Expression of EMT, and fibrosis markers, as well as TGF-β1 signaling, were analyzed using western blot, reverse transcription quantitative PCR (RT-qPCR), enzyme-linked immunosorbent assay (ELISA), and immunostaining. Results: In both animal models, platelet inhibition or depletion resulted in reduced expression of cell cycle arrest marker p21, partial EMT and fibrosis. In vitro, activated platelets stimulated cell cycle arrest, EMT, and fibrosis in TECs and kidney organoids. Chronically injured TECs experience cell-cycle arrest which promote a paracrine EMT program in TECs, jointly leading to fibrosis. This platelet-mediated effect on cell cycle arrest and EMT was driven by TGF-β1 signaling, as selective inhibition of the TGF-β receptor rescued these dysfunctional phenotypes. Conclusions: Our study demonstrates that platelets activate the TGF-β1 pathway, leading to cell cycle arrest, EMT and renal fibrosis. These findings suggest that antiplatelet therapies may have potential renoprotective effects by protecting tubular homeostasis, attenuating partial EMT and fibrosis.

Bipolar disorder (BD) is a complex psychiatric condition usually requiring long-term treatment. Lithium (Li) remains the most effective mood stabilizer for BD, yet it benefits only a subset of patients, and its precise mechanism of action remains elusive. Exome sequencing has identified AKAP11 (A-kinase anchoring protein 11) as a shared risk gene for BD and schizophrenia (SCZ). Given that both the AKAP11-Protein Kinase A (PKA) complex and Li target and inhibit Glycogen Synthase Kinase-3 beta (GSK3β), we hypothesize that Li may partially normalize the transcriptomic and/or epigenomic alterations observed in heterozygous AKAP11-knockout (Het-AKAP11-KO) iPSC-derived neurons. In this study, we employed genome-wide approaches to assess the effects of Li on the transcriptome and epigenome of human iPSC-derived Het-AKAP11-KO neuronal culture. We show that chronic Li treatment in this cellular model upregulates key pathways that were initially downregulated by Het-AKAP11-KO, several of which have also been reported as downregulated in synapses of BD and SCZ post-mortem brain tissues. Moreover, we demonstrated that Li treatment partially rescues certain transcriptomic alterations resulting from Het-AKAP11-KO, bringing them closer to the WT state. We suggest two possible mechanisms underlying these transcriptomic effects: (1) Li modulates histone H3K27ac levels at intergenic and intronic enhancers, influencing enhancer activity and transcription factor binding, and (2) Li enhances GSK3β serine 9 phosphorylation, impacting WNT/β-catenin signaling and downstream transcription. These findings underscore Li’s potential as a therapeutic agent for BD and SCZ patients carrying AKAP11 loss-of-function variants or exhibiting similar pathway alterations to those observed in Het-AKAP11-KO models.