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Small cell lung cancer (SCLC) transformation is an incompletely characterized mechanism of resistance to epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) in EGFR-mutant cancers, limiting development of optimal treatment approaches. Through single-cell RNA sequencing of malignant pleural effusions from patients who underwent SCLC transformation, we identified heterogeneity and diversity, including distinct neuroendocrine (NE) and mesenchymal non-NE cancer cell subsets, which were maintained in patient-derived cell lines. We demonstrate that EZH2 regulates EGFR expression in NE cells where EGFR expression is silenced at baseline. Although neither epigenetic derepression nor exogenous overexpression of mutant EGFR sensitized the cells to EGFR inhibition, non-NE cells exhibited selective sensitivity to MEK inhibitors. Combined MEK inhibitor and chemotherapy effectively inhibited growth of both NE and non-NE cells in vitro and in vivo. Our findings demonstrate that EGFR-mutant SCLC is composed of mixed cell states with distinct therapeutic vulnerabilities and offer a therapeutic strategy to target tumor heterogeneity in highly plastic and treatment-resistant malignancies such as transformed SCLC.

The TRPV4 skeletal dysplasias are characterized by short stature, short limbs with prominent large joints, and progressive scoliosis. They result from dominant missense mutations that activate the TRPV4 calcium permeable ion channel. As a platform to understand the mechanism of disease and to test the hypothesis that channel inhibition could treat these disorders, we developed a knock-in mouse that conditionally expresses the p.R594H Trpv4 mutation. Embryonic, chondrocyte-specific induction of the mutation using Col2a1-Cre resulted in a skeletal dysplasia affecting the long bones, spine, and craniofacial skeletal elements, consistent with the human skeletal dysplasia phenotypes produced by TRPV4 mutations. Cartilage growth plate histological abnormalities included disorganized proliferating chondrocyte columns and reduced hypertrophic chondrocyte development, reflecting abnormal endochondral ossification. In vivo treatment with the TRPV4-specific inhibitor GSK2798745 markedly improved the radiographic skeletal phenotype and rescued the growth plate histological abnormalities. ScRNA-Seq of chondrocyte transcripts from affected mice identified calcium-mediated effects on multiple signaling pathways as potential mechanisms underlying the defects in linear and cartilage appositional growth observed in both mutant mice and patients. These results provide preclinical evidence demonstrating TRPV4 inhibition as a rational, mechanism-based therapeutic strategy to ameliorate disease progression and severity in the TRPV4 skeletal dysplasias.

BACKGROUNDAfter identifying 2 immunomarkers of acute injury, KIM-1 and LCN2, in all kidney biopsies from 31 patients with COVID-19 pneumonia and de novo kidney dysfunction, we investigated whether circulating markers of kidney epithelial injury are common in patients with laboratory-confirmed COVID-19 who require oxygen support but do not have critical illness.METHODSWe studied 196 patients admitted to 15 hospitals with moderate to severe pneumonia who were enrolled in 2 independent randomized clinical trials. We measured 41 immune mediators and markers of kidney and endothelial injury in peripheral blood in these patients within 24 hours of randomization.RESULTSWe constructed a generalized linear CORIMUNO model combining serum levels of KIM-1, LCN2, IL-10, and age at hospital admission that showed high discrimination for mortality (derivation cohort: AUC = 0.82, 95% CI: 0.73-0.92; validation cohort: AUC = 0.83, 95% CI: 0.74-0.92). An early rise in circulating kidney injury markers, in the absence of acute kidney injury criteria, was markedly associated with the risk of developing a severe form of COVID-19 and death within 3 months.CONCLUSIONThe CORIMUNO score may be a helpful tool for risk stratification, and for the first time to our knowledge, it identifies the overlooked impact of subclinical kidney injury on pneumonia outcomes.TRIAL REGISTRATIONClinicalTrials.gov NCT04324047, NCT04324073, and NCT04331808.FUNDINGThis research was funded by the French Ministry of Health, Programme Hospitalier de Recherche Clinique (PHRC COVID-19-20-0151, PHRC COVID-19-20-0029), Fondation de l'Assistance Publique Hôpitaux de Paris (Alliance Tous Unis Contre le Virus), Assistance Publique Hôpitaux de Paris, and grants from the Fondation pour la Recherche Médicale (FRM) (REA202010012514) and Agence Nationale de Recherches sur le Sida and emerging infectious diseases (ANRS) (ANRS0147) from the VINTED sponsorship.

Acute severe joint pain is a major symptom in gouty arthritis (GA), and its adequate treatment represents an unmet medical need. Mrgprb2, a specific mast cell receptor, has been implicated in the generation of chronic pain by mobilizing mast cell degranulation, yet its significance in GA pain and joint inflammation is still not well defined. Here, we found that Mrgprb2 was expressed in mouse synovial mast cells. In a murine model of GA, acute blockade or genetic deletion of Mrgprb2 significantly attenuated arthritis pain and hyperexcitability of joint nociceptors with significant reductions in innate immune cell recruitment in the synovium. Under naive conditions, activation of synovial Mrgprb2 was sufficient to excite peripheral terminals of joint nociceptors to induce acute joint hypernociception via the mobilization of mast cell degranulation. Additionally, the level of the neuropeptide substance P (SP) was elevated in the synovium of GA model mice. Using humanized MRGPRX2-knockin mice, we revealed that SP contributed to joint pain and inflammation by activating mast cells through Mrgprb2/MRGPRX2. These findings suggest that synovial mast cell-expressed Mrgprb2/MRGPRX2 merits consideration as a key neuroimmune player and a potential therapeutic target for treating GA pain and joint inflammation.

Mitochondria-derived acyl-coenzyme A (acyl-CoA) species chemically modify proteins, causing damage when acylation reactions are not adequately detoxified by enzymatic removal or protein turnover. Defects in genes encoding the mitochondrial respiratory complex and TCA cycle enzymes have been shown to increase acyl-CoA levels due to reduced enzymatic flux and result in proteome-wide hyperacylation. How pathologically elevated acyl-CoA levels contribute to bioenergetics failure in mitochondrial diseases is not well understood. Here, we demonstrate that bulk succinylation from succinyl-CoA excess consumes the enzymatic cofactor NAD+ and propagates mitochondrial respiratory defects in a zebrafish model of succinyl-CoA ligase deficiency, a childhood-onset encephalomyopathy. To explore this mechanism as a therapeutic target, we developed a workflow to monitor behavioral defects in sucla2-/- zebrafish and show that hypersuccinylation is associated with reduced locomotor behavior and impaired ability to execute food hunting patterns. Postembryonic NAD+ precursor supplementation restores NAD+ levels and improves locomotion and survival of sucla2-/- zebrafish. Mechanistically, nicotinamide and nicotinamide riboside require the NAD+-dependent desuccinylase Sirt5 to enhance oxidative metabolism and nitrogen elimination through the urea cycle. Collectively, NAD+ supplementation activates Sirt5 to protect against damage to mitochondria and locomotor circuits caused by protein succinylation.

Treatment with anti-CD3 monoclonal antibody (mAb) can delay or prevent type 1 diabetes in mice and humans by modulating the immune-mediated destruction of β cells. A single course of treatment may have lasting efficacy, but the mechanisms that account for these prolonged effects, i.e., "operational tolerance," are not clear. Here, we used paired single-cell RNA and T cell receptor sequencing to characterize islet-infiltrating T cells and their counterpart in paired pancreatic lymph nodes from anti-CD3 mAb-treated nonobese diabetic (NOD) mice in remission. We found that after anti-CD3 mAb treatment, T cells that infiltrate the islets are more heterogeneous and have hybrid features including characteristics of T stem cell-like memory and reduced effector function compared with those from untreated prediabetic NOD mice. Autoantigen-reactive CD8+ T cells persist after treatment, but they also show features of stemness and reduced pathogenicity. Our findings describe the reshaping of islet-infiltrating and autoreactive T cells and β cells that lead to operational, but tenuous, tolerance to autoimmune diabetes following anti-CD3 mAb treatment.

The human endometrium undergoes dynamic changes across the menstrual cycle to establish a receptive state for embryo implantation. Using bulk and single-cell RNA-Seq, we characterized gene expression dynamics in the cycling endometrium and the decidua from early pregnancy. We demonstrated that during the mid-secretory phase - the period encompassing the window of implantation - secretory glandular epithelial cells undergo notable transcriptional changes and alterations in cell-cell communication. Through comprehensive analyses, we identified the glandular epithelium receptivity module (GERM) signature, comprising 556 genes associated with endometrial receptivity. This GERM signature was consistently perturbed across datasets of endometrial samples from women with impaired fertility, validating its relevance as a marker of receptivity. In addition to epithelial changes, we observed shifts in stromal cell populations, notably involving decidual and senescent subsets, which also play key roles in modulating implantation. Together, these findings provide a high-resolution transcriptomic atlas of the receptive and early pregnant endometrium and shed light on key molecular pathways underlying successful implantation.

Approximately 30% of patients with endometrial carcinomas (ECs) with exon 3 CTNNB1 (β-catenin) mutations experience disease recurrence, whereas others with the same mutations remain recurrence-free. The molecular factors driving mutant β-catenin's oncogenic and clinical variability are unknown. Here we show that CD73 restrains the oncogenic activity of exon 3 β-catenin mutants, and CD73 loss is associated with recurrence. Using 7 patient-specific β-catenin mutants, together with genetic deletion or ectopic expression of CD73, we demonstrate that CD73 loss increases β-catenin-TCF/LEF transcriptional activity. In CD73-deficient cells, membrane levels of mutant β-catenin decreased, which corresponded with increased levels of nuclear and chromatin-bound mutant β-catenin. These results suggest that CD73 sequesters mutant β-catenin to the membrane to limit its oncogenic activity. Adenosine A1 receptor deletion phenocopied the effects of CD73 loss, implicating adenosine receptor signaling in this regulation. Ectopic CD73 expression suppressed the invasiveness and stemness capacity of β-catenin-mutant EC cells. TCGA analyses, GeoMx digital spatial profiling, and functional analyses showed that CD73 loss drives distinct Wnt-TCF/LEF-dependent gene expression programs linked to cancer cell stemness. These findings identify CD73 as a key regulator of mutant β-catenin, providing mechanistic insight into the variability of recurrence in CTNNB1-mutant EC.

Nearly 50% of patients with KRAS-mutant colorectal cancer (CRC) currently lack effective targeted therapy. The accumulation of KRAS-mutant proteins can trigger a sustained high level of endoplasmic reticulum (ER) stress, and the UPR-based long-term protective regulatory pathway inhibits the aggregation of unfolded proteins, thereby maintaining the stability of the ER and enabling the continued survival of KRAS-mutant tumors. However, the critical factors that affect the regulation of ER homeostasis in KRAS-mutant CRC are still unclear. Mono-ADP ribosylation (MARylation) catalyzed by ART1 is the most important modification of GRP78/BiP and stabilizes the internal environment of the ER. In this study, KRAS mutation increased the levels of ART1, ER stress, and MARylated GRP78/BiP in CRC cells. Inhibiting MARylated GRP78/BiP can impede the downstream IRE1α/XBP1/TFAF2/JNK and PERK/eIF2α/ATF4 cascades by affecting the binding and dissociation of GRP78/BiP with receptors to hinder the growth of KRAS-mutant CRC cells and accelerate their apoptosis. We propose that KRAS-mutant CRC cells are more sensitive to intervention with MARylated GRP78/BiP because more modifications are needed to maintain ER stability. We also conducted a preliminary study on the specific site of function. Clarifying this molecular mechanism can provide a experimental basis for identifying effective targets for the intervention of KRAS-mutant CRC.

Rheumatoid arthritis (RA) is characterized by joint inflammation and bone erosion. Understanding cytokine pathways, particularly those targeting TNF, is crucial for understanding pathology and advancing treatment development. Arid5a is a noncanonical RNA binding protein (RBP) that augments inflammation through stabilizing proinflammatory mRNAs and enhancing protein translation. We examined published datasets for ARID5A in human RA blood, T cells, and synovial tissues. A stromal cell line, epithelial cells, and primary synovial fibroblasts were used to assess the effect of TNF on Arid5a expression, localization, and function. To determine how TNF induces Arid5a, WT or Traf2-/- stromal cells were treated with NIK or IKK inhibitors. To evaluate the necessity of Arid5a in arthritis progression, Arid5a-/- mice were subjected to collagen-induced arthritis. ARID5A was elevated in patients with RA and reduced by anti-TNF therapy. TNF upregulated Arid5a through the NF-κB1/TRAF2 pathway, causing cytoplasmic relocalization. Arid5a stabilized proinflammatory transcripts and enhanced expression of chemokines that drive RA. Arid5a-/- mice were resistant to collagen-induced arthritis correlating with reduced Th17 cells in synovial tissue. Thus, Arid5a serves as a newly recognized signaling intermediate downstream of TNF that is elevated in human RA and drives pathology in murine CIA, potentially positioning this RBP as a possible therapeutic target.