[Veno-venous extracorporeal membrane oxygenation for capillary leak syndrome during induction chemotherapy in acute myeloid leukemia].

A 44-year-old woman was diagnosed with acute myeloid leukemia (RUNX1::RUNX1T1 translocation) and received induction chemotherapy with idarubicin hydrochloride and cytosine arabinoside. The pneumonia that had been present since admission worsened, and a drug-induced skin rash appeared. On day 17, she presented with respiratory failure and shock, complicated by hemoconcentration and hypoalbuminemia. This was considered capillary leak syndrome due to pneumonia and drug allergy, so she was started on pulse steroid therapy and IVIG, and was intubated on the same day. On day 18, venovenous-extracorporeal membrane oxygenation (VV-ECMO) was started due to worsening blood gas parameters despite ventilatory management. Bronchoalveolar lavage fluid was serous, and both blood and sputum cultures yielded negative. The patient was weaned from VV-ECMO on day 26 as the pneumonia improved with recovery of hematopoiesis. She was disoriented, and a CT scan on day 28 revealed cerebral hemorrhage. Her strength recovered with rehabilitation. After induction chemotherapy, RUNX1::RUNX1T1 mRNA was not detected in bone marrow. The patient received consolidation chemotherapy, and has maintained complete remission. Severe respiratory failure during induction chemotherapy for acute leukemia can be fatal, but VV-ECMO may be lifesaving.

IGLL5 controlled by super-enhancer affects cell survival and MYC expression in mature B-cell lymphoma.

IGLL5 is shown to be located near super-enhancer (SE) in B-cell tumors, and this gene is frequently mutated and a target of translocation in B-cell tumors. These results suggest roles of the IGLL5 in tumorigenesis; however, its functional properties have been unclear. We found that two mature B-cell lymphoma cell lines expressed IGLL5 mRNA with Cλ1 segment. JQ1 treatment resulted in down-expression of IGLL5, indicating that IGLL5 is controlled by SE. IGLL5 knockdown induced cell death with down-expression of MYC. Our results suggested that IGLL5 might have a role in survival of mature B-cell tumors and involvement in MYC expression. (100 words).

Mitotic Spindle Positioning (MISP) Facilitates Colorectal Cancer Progression by Forming a Complex with Opa Interacting Protein 5 (OIP5) and Activating the JAK2-STAT3 Signaling Pathway.

Patients with inflammatory bowel disease (IBD) who experience long-term chronic inflammation of the colon are at an increased risk of developing colorectal cancer (CRC). Mitotic spindle positioning (MISP), an actin-binding protein, plays a role in mitosis and spindle positioning. MISP is found on the apical membrane of the intestinal mucosa and helps stabilize and elongate microvilli, offering protection against colitis. This study explored the role of MISP in colorectal tumorigenesis using a database, human CRC cells, and a mouse model for colitis-induced colorectal tumors triggered by azoxymethane (AOM)/dextran sodium sulfate (DSS) treatment. We found that MISP was highly expressed in colon cancer patient tissues and that reduced MISP expression inhibited cell proliferation. Notably, MISP-deficient mice showed reduced colon tumor formation in the AOM/DSS-induced colitis model. Furthermore, MISP was found to form a complex with Opa interacting protein 5 (OIP5) in the cytoplasm, influencing the expression of OIP5 in a unidirectional manner. We also observed that MISP increased the levels of phosphorylated STAT3 in the JAK2-STAT3 signaling pathway, which is linked to tumorigenesis. These findings indicate that MISP could be a risk factor for CRC, and targeting MISP might provide insights into the mechanisms of colitis-induced colorectal tumorigenesis.

The neutrophil-osteogenic cell axis promotes bone destruction in periodontitis.

The immune-stromal cell interactions play a key role in health and diseases. In periodontitis, the most prevalent infectious disease in humans, immune cells accumulate in the oral mucosa and promote bone destruction by inducing receptor activator of nuclear factor-κB ligand (RANKL) expression in osteogenic cells such as osteoblasts and periodontal ligament cells. However, the detailed mechanism underlying immune-bone cell interactions in periodontitis is not fully understood. Here, we performed single-cell RNA-sequencing analysis on mouse periodontal lesions and showed that neutrophil-osteogenic cell crosstalk is involved in periodontitis-induced bone loss. The periodontal lesions displayed marked infiltration of neutrophils, and in silico analyses suggested that the neutrophils interacted with osteogenic cells through cytokine production. Among the cytokines expressed in the periodontal neutrophils, oncostatin M (OSM) potently induced RANKL expression in the primary osteoblasts, and deletion of the OSM receptor in osteogenic cells significantly ameliorated periodontitis-induced bone loss. Epigenomic data analyses identified the OSM-regulated RANKL enhancer region in osteogenic cells, and mice lacking this enhancer showed decreased periodontal bone loss while maintaining physiological bone metabolism. These findings shed light on the role of neutrophils in bone regulation during bacterial infection, highlighting the novel mechanism underlying osteoimmune crosstalk.

Comparison of the outcomes of patients with primary central nervous system lymphoma between the neurosurgery and hematology/oncology departments based on the relative dose intensity of methotrexate.

Primary central nervous system lymphoma (PCNSL) is an extranodal type of lymphoma, which is treated with methotrexate (MTX)-based induction therapy. Although PCNSL is a hematological malignancy, patients with PCNSL may be treated at neurosurgery or hematology/oncology departments; however, the outcomes of PCNSL treatment have not been compared between these two departments. The present study compared the outcomes of 26 patients with newly diagnosed PCNSL that were treated at the Department of Neurological Surgery or Department of Hematology/Oncology (Wakayama Medical University Hospital, Wakayama, Japan) between January 2011 and December 2021. The relative dose intensity (RDI) and relative treatment intensity of MTX were assessed as indicators of the intensity of chemotherapy. The median RDI of MTX was 67 and 93% in the neurosurgery and hematology/oncology groups, respectively (P<0.001). The proportion of patients that achieved a complete response after high-dose MTX-based therapy was significantly higher in the hematology/oncology group than in the neurosurgery group (P=0.038). The estimated 2-year overall survival was 72 and 100% in the neurosurgery and hematology/oncology groups, respectively (P=0.046). As with the difference in the outcomes observed between pediatrics and hematology departments for adolescents with acute lymphoblastic leukemia, the outcomes of patients with PCNSL may differ between neurosurgery and hematology/oncology departments.

Ameliorated Renal Pathological Feature in MRL/MpJ-Faslpr/lpr Background Interleukin-36 Receptor-Deficient Mice.

Systemic autoimmune diseases frequently induce lupus nephritis, causing altered balance and expression of interleukin 36 receptor (IL-36R) ligands, including agonists (IL-36α, ß, γ) and antagonists (IL-36Ra, IL-38), in kidneys. Here, we established and analyzed a mouse model of lupus nephritis, MRL/MpJ-Faslpr/lpr with IL-36R-knockout (KO), compared to wild-type (WT) mice. In both genotypes, indices for immune abnormalities and renal functions were comparable, although female WT mice showed higher serum autoantibody levels than males. IL-36R ligand expression did not differ significantly between genotypes at the mRNA level or in IL-36α and IL-38 scores. However, glomerular lesions, especially mesangial matrix expansion, were significantly ameliorated in both sexes of IL-36R-KO mice compared to WT mice. Cell infiltration into the tubulointerstitium with the development of tertiary lymphoid structures was comparable between genotypes. However, the positive correlation with the IL-36α score in WT mice was not evident in IL-36R-KO mice. Fibrosis was less in female IL-36R-KO mice than in WT mice. Importantly, some IL-36α+ nuclei co-localized with acetylated lysine and GCN5 histone acetyltransferase, in both genotypes. Therefore, IL-36R ligands, especially IL-36α, contribute to the progression of renal pathology in lupus nephritis via IL-36R-dependent and IL-36R-independent pathways.

Identification of an intronic enhancer regulating RANKL expression in osteocytic cells.

The bony skeleton is continuously renewed throughout adult life by the bone remodeling process, in which old or damaged bone is removed by osteoclasts via largely unknown mechanisms. Osteocytes regulate bone remodeling by producing the osteoclast differentiation factor RANKL (encoded by the TNFSF11 gene). However, the precise mechanisms underlying RANKL expression in osteocytes are still elusive. Here, we explored the epigenomic landscape of osteocytic cells and identified a hitherto-undescribed osteocytic cell-specific intronic enhancer in the TNFSF11 gene locus. Bioinformatics analyses showed that transcription factors involved in cell death and senescence act on this intronic enhancer region. Single-cell transcriptomic data analysis demonstrated that cell death signaling increased RANKL expression in osteocytic cells. Genetic deletion of the intronic enhancer led to a high-bone-mass phenotype with decreased levels of RANKL in osteocytic cells and osteoclastogenesis in the adult stage, while RANKL expression was not affected in osteoblasts or lymphocytes. These data suggest that osteocytes may utilize a specialized regulatory element to facilitate osteoclast formation at the bone surface to be resorbed by linking signals from cellular senescence/death and RANKL expression.

Susceptibility to adriamycin-induced hepatotoxicity in mice depends on PRKDC polymorphism.

Adriamycin (ADR) is an effective chemotherapy drug for various cancers but has serious side effects. ADR-induced liver damage is a common problem during therapy, but the underlying mechanism remains to be fully understood. In contrast, ADR-induced glomerular damage is well studied in rodents, and sensitivity to ADR-induced nephropathy is because of the R2140C polymorphism of Prkdc gene. To investigate whether strain differences or sensitivity to ADR-induced liver damage are related to Prkdc polymorphism, this study compared the sensitivity to ADR-induced liver damage among C57BL/6J (B6J), B6-PrkdcR2140C, and BALB/c mice. Although B6J exhibits resistance to ADR-induced liver injury, BALB/c and B6-PrkdcR2140C are more susceptible to liver injury, which is exacerbated by the presence of R2140C mutation in PRKDC.

Dietary omega-3 fatty acid does not improve male infertility caused by lysophospholipid acyltransferase 3 (LPLAT3/AGPAT3) deficiency.

Docosahexaenoic acid (DHA), an omega-3 fatty acid, usually presents as a constituent of phospholipids in the cellular membrane. Lysophospholipid acyltransferase 3 (LPLAT3; AGPAT3) is the primary enzyme that incorporates DHA into phospholipids. LPLAT3-KO mice show male infertility and visual dysfunction accompanied by decreased phospholipids (PLs) containing DHA (PL-DHA) in the testis and retina, respectively. In this study, we evaluated the effect of diets consisting mainly of triacylglycerol-bound DHA (fish oil) and PL-bound DHA (salmon roe oil) on the amount of PL-DHA in a broad range of tissues and on reproductive functions. Both diets elevated phosphatidylcholines (PCs)-containing DHA in most tissues of wild type (WT) mice. Although LPLAT3-KO mice acquired a minimal amount of PC-DHA in the testes and sperm by eating either of the diets, reproductive function did not improve. The present study suggests that DHA-rich diets do not restore sufficient PL-DHA to improve male infertility in LPLAT3-KO mice. Alternatively, PL-DHA can be biosynthesized by LPLAT3 but not by external supplementation, which may be necessary for normal reproductive function.

Molecular and Pathological Analyses of IARS1-Deficient Mice: An IARS Disorder Model.

Most mitochondrial diseases are hereditary and highly heterogeneous. Cattle born with the V79L mutation in the isoleucyl-tRNA synthetase 1 (IARS1) protein exhibit weak calf syndrome. Recent human genomic studies about pediatric mitochondrial diseases also identified mutations in the IARS1 gene. Although severe prenatal-onset growth retardation and infantile hepatopathy have been reported in such patients, the relationship between IARS mutations and the symptoms is unknown. In this study, we generated hypomorphic IARS1V79L mutant mice to develop an animal model of IARS mutation-related disorders. We found that compared to wild-type mice, IARSV79L mutant mice showed a significant increase in hepatic triglyceride and serum ornithine carbamoyltransferase levels, indicating that IARS1V79L mice suffer from mitochondrial hepatopathy. In addition, siRNA knockdown of the IARS1 gene decreased mitochondrial membrane potential and increased reactive oxygen species in the hepatocarcinoma-derived cell line HepG2. Furthermore, proteomic analysis revealed decreased levels of the mitochondrial function-associated protein NME4 (mitochondrial nucleoside diphosphate kinase). Concisely, our mutant mice model can be used to study IARS mutation-related disorders.

Mesenchymal loss of p53 alters stem cell capacity and models human soft tissue sarcoma traits.

Soft tissue sarcomas (STSs) are a heterogeneous group of tumors that originate from mesenchymal cells. p53 is frequently mutated in human STS. In this study, we found that the loss of p53 in mesenchymal stem cells (MSCs) mainly causes adult undifferentiated soft tissue sarcoma (USTS). MSCs lacking p53 show changes in stem cell properties, including differentiation, cell cycle progression, and metabolism. The transcriptomic changes and genetic mutations in murine p53-deficient USTS mimic those seen in human STS. Furthermore, single-cell RNA sequencing revealed that MSCs undergo transcriptomic alterations with aging-a risk factor for certain types of USTS-and that p53 signaling decreases simultaneously. Moreover, we found that human STS can be transcriptomically classified into six clusters with different prognoses, different from the current histopathological classification. This study paves the way for understanding MSC-mediated tumorigenesis and provides an efficient mouse model for sarcoma studies.

Mice lacking nucleotide sugar transporter SLC35A3 exhibit lethal chondrodysplasia with vertebral anomalies and impaired glycosaminoglycan biosynthesis.

SLC35A3 is considered an uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) transporter in mammals and regulates the branching of N-glycans. A missense mutation in SLC35A3 causes complex vertebral malformation (CVM) in cattle. However, the biological functions of SLC35A3 have not been fully clarified. To address these issues, we have established Slc35a3-/-mice using CRISPR/Cas9 genome editing system. The generated mutant mice were perinatal lethal and exhibited chondrodysplasia recapitulating CVM-like vertebral anomalies. During embryogenesis, Slc35a3 mRNA was expressed in the presomitic mesoderm of wild-type mice, suggesting that SLC35A3 transports UDP-GlcNAc used for the sugar modification that is essential for somite formation. In the growth plate cartilage of Slc35a3-/-embryos, extracellular space was drastically reduced, and many flat proliferative chondrocytes were reshaped. Proliferation, apoptosis and differentiation were not affected in the chondrocytes of Slc35a3-/-mice, suggesting that the chondrodysplasia phenotypes were mainly caused by the abnormal extracellular matrix quality. Because these histological abnormalities were similar to those observed in several mutant mice accompanying the impaired glycosaminoglycan (GAG) biosynthesis, GAG levels were measured in the spine and limbs of Slc35a3-/-mice using disaccharide composition analysis. Compared with control mice, the amounts of heparan sulfate, keratan sulfate, and chondroitin sulfate/dermatan sulfate, were significantly decreased in Slc35a3-/-mice. These findings suggest that SLC35A3 regulates GAG biosynthesis and the chondrodysplasia phenotypes were partially caused by the decreased GAG synthesis. Hence, Slc35a3-/- mice would be a useful model for investigating the in vivo roles of SLC35A3 and the pathological mechanisms of SLC35A3-associated diseases.

Dystrophin Short Product, Dp71, Interacts with AQP4 and Kir4.1 Channels in the Mouse Cerebellar Glial Cells in Contrast to Dp427 at Inhibitory Postsynapses in the Purkinje Neurons.

Dystrophin is the causative gene for Duchenne and Becker muscular dystrophy (DMD/BMD), and it produces full-length and short dystrophin, Dp427 and Dp71, respectively, in the brain. The existence of the different dystrophin molecular complexes has been known for a quarter century, so it is necessary to derive precise expression profiles of the molecular complexes in the brain to elucidate the mechanism of cognitive symptoms in DMD/BMD patients. In order to investigate the Dp71 expression profile in cerebellum, we employed Dp71-specific tag-insertion mice, which allowed for the specific detection of endogenous Dp71 in the immunohistochemical analysis and found its expressions in the glial cells, Bergmann glial (BG) cells, and astrocytes, whereas Dp427 was exclusively expressed in the inhibitory postsynapses within cerebellar Purkinje cells (PCs). Interestingly, we found different cell-type dependent dystrophin molecular complexes; i.e., glia-associated Dp71 was co-expressed with dystroglycan (DG) and dystrobrevinα, whereas synapse-associated Dp427 was co-expressed with DG and dystrobrevinß. Furthermore, we investigated the molecular relationship of Dp71 to the AQP4 water channel and the Kir4.1 potassium channel, and found biochemical associations of Dp71 with AQP4 and Kir4.1 in both the cerebellum and cerebrum. Immunohistochemical and cytochemical investigations revealed partial co-localizations of Dp71 with AQP4 and Kir4.1 in the glial cells, indicating Dp71 interactions with the channels in the BG cells and astrocytes. Taken together, different cell-types, glial cells and Purkinje neurons, in the cerebellum express different dystrophin molecular complexes, which may contribute to pathological and physiological processes through the regulation of the water/ion channel and inhibitory postsynapses.

Robust protein-based engineering of hepatocyte-like cells from human mesenchymal stem cells.

BACKGROUND: Cells of interest can be prepared from somatic cells by forced expression of lineage-specific transcription factors, but it is required to establish a vector-free system for their clinical use. Here, we report a protein-based artificial transcription system for engineering hepatocyte-like cells from human umbilical cord-derived mesenchymal stem cells (MSCs). METHODS: MSCs were treated for 5 days with 4 artificial transcription factors (4F), which targeted hepatocyte nuclear factor (HNF)1α, HNF3γ, HNF4α, and GATA-binding protein 4 (GATA4). Then, engineered MSCs (4F-Heps) were subjected to epigenetic analysis, biochemical analysis and flow cytometry analysis with antibodies to marker proteins of mature hepatocytes and hepatic progenitors such as delta-like homolog 1 (DLK1) and trophoblast cell surface antigen 2 (TROP2). Functional properties of the cells were also examined by injecting them to mice with lethal hepatic failure. RESULTS: Epigenetic analysis revealed that a 5-day treatment of 4F upregulated the expression of genes involved in hepatic differentiation, and repressed genes related to pluripotency of MSCs. Flow cytometry analysis detected that 4F-Heps were composed of small numbers of mature hepatocytes (at most 1%), bile duct cells (~19%) and hepatic progenitors (~50%). Interestingly, ~20% of 4F-Heps were positive for cytochrome P450 3A4, 80% of which were DLK1-positive. Injection of 4F-Heps significantly increased survival of mice with lethal hepatic failure, and transplanted 4F-Heps expanded to more than 50-fold of human albumin-positive cells in the mouse livers, well consistent with the observation that 4F-Heps contained DLK1-positive and/or TROP2-positive cells. CONCLUSION: Taken together with observations that 4F-Heps were not tumorigenic in immunocompromised mice for at least 2 years, we propose that this artificial transcription system is a versatile tool for cell therapy for hepatic failures.

Identification of SARS-CoV-2 Mpro inhibitors containing P1' 4-fluorobenzothiazole moiety highly active against SARS-CoV-2.

COVID-19 caused by SARS-CoV-2 has continually been serious threat to public health worldwide. While a few anti-SARS-CoV-2 therapeutics are currently available, their antiviral potency is not sufficient. Here, we identify two orally available 4-fluoro-benzothiazole-containing small molecules, TKB245 and TKB248, which specifically inhibit the enzymatic activity of main protease (Mpro) of SARS-CoV-2 and significantly more potently block the infectivity and replication of various SARS-CoV-2 strains than nirmatrelvir, molnupiravir, and ensitrelvir in cell-based assays employing various target cells. Both compounds also block the replication of Delta and Omicron variants in human-ACE2-knocked-in mice. Native mass spectrometric analysis reveals that both compounds bind to dimer Mpro, apparently promoting Mpro dimerization. X-ray crystallographic analysis shows that both compounds bind to Mpro's active-site cavity, forming a covalent bond with the catalytic amino acid Cys-145 with the 4-fluorine of the benzothiazole moiety pointed to solvent. The data suggest that TKB245 and TKB248 might serve as potential therapeutics for COVID-19 and shed light upon further optimization to develop more potent and safer anti-SARS-CoV-2 therapeutics.

Mitotic spindle positioning protein (MISP) deficiency exacerbates dextran sulfate sodium (DSS)-induced colitis in mice.

Inflammatory bowel disease (IBD) is classified into two types: Crohn's disease and ulcerative colitis. In IBD, the imbalance between the pro-inflammatory and anti-inflammatory cytokines prevents recovery from the inflammatory state, resulting in chronic inflammation in the colon. The mitotic spindle positioning protein (MISP) is localized to the apical membrane in the colon. In this study, we observed increased expression of MISP in the intestinal epithelial cells in dextran sulfate sodium (DSS)-induced colitis in mice. MISP-deficient mice receiving DSS showed significant exacerbation of colitis (e.g., weight loss, loss of the crypts). The intestinal epithelial cells of the MISP-deficient mice showed a trend towards decreased cell proliferation after DSS treatment. Reverse transcription followed by quantitative polymerase chain reaction revealed that the expression levels of Tgfb1, an anti-inflammatory cytokine, were significantly reduced in the colon of MISP-deficient mice compared with the wild-type mice regardless of DSS treatment. These findings indicate that MISP may play a role in the recovery of the colon after inflammation through its anti-inflammatory and proliferative activities, suggesting that MISP may be a new therapeutic target for IBD.

Genetic background strongly influences the transition to chronic kidney disease of adriamycin nephropathy in mice.

Animal models of podocytopathy and chronic kidney diseases (CKD) help elucidate these pathologies. Adriamycin (ADR)-induced nephropathy is a common rodent model of podocytopathy. BALB/c mice are sensitive to ADR, whereas C57BL/6 (B6) mice, the most commonly used strain, are resistant to ADR. Therefore, mouse strains with the B6 genetic background cannot be used as an ADR nephropathy model. We previously generated DNA-dependent protein kinase catalytic subunit (Prkdc) mutant B6 mice (B6-PrkdcR2140C) carrying the R2140C mutation that causes ADR nephropathy. However, whether ADR nephropathy in the novel strain progresses to CKD after ADR administration has not been evaluated. Therefore, we examined whether the B6-PrkdcR2140C mice develop CKD after ADR administration. We also evaluated whether differences existed in the genetic background in ADR nephropathy by comparing the B6-PrkdcR2140C mice with BALB/c mice. Our findings demonstrated that B6-PrkdcR2140C progresses to CKD and is resistant to nephropathy compared with the BALB/c mice. The B6-PrkdcR2140C and BALB/c mice differed in the expression of genes related to inflammatory mediators, and further analysis is required to identify factors that contribute to resistance to nephropathy.

Peripheral-dominant liver fibrosis and tumor distribution in a mouse model of congestive hepatopathy.

AIM: Congestive hepatopathy often leads to liver fibrosis and hepatocellular carcinoma. Imaging modalities provided clinical evidence that elevation of liver stiffness and tumor occurrence are mainly induced in the periphery of the liver in patients with congestive hepatopathy. However, clinical relevance of liver stiffness and liver fibrosis is unclear because liver congestion itself increases liver stiffness in congestive hepatopathy. It also unclear which factors configure such regional disparity of tumor development in patients with congestive hepatopathy. To answer these questions, we evaluated the macroscopic spatial distribution of liver fibrosis and tumors in the murine model of congestive hepatopathy. METHODS: Chronic liver congestion was induced by partial ligation of the suprahepatic inferior vena cava. Distribution of liver congestion, fibrosis, and tumors in partial ligation of the suprahepatic inferior vena cava mice were assessed by histological findings, laser microdissection (LMD)-based qPCR and enhanced computed tomography. LMD-based RNA-sequencing was performed to identify causal factors that promote tumor development in congestive hepatopathy. RESULTS: Liver fibrosis was mainly induced in the periphery of the liver and co-localized with distribution of liver congestion. Liver tumors were also induced in the periphery of the liver where liver congestion and fibrosis occurred. LMD-based RNA-sequencing revealed the upregulation of extracellular matrix/collagen fibril-, wound healing-, angiogenesis-, morphogenesis-, and cell motility-related signaling pathways in periphery of liver compared with liver center. CONCLUSIONS: Our findings showed the experimental relevance of liver congestion, fibrosis, and tumor development in congestive hepatopathy, and may provide important locational information. Macroscopic regional disparity observed in this murine model should be considered to manage patients with congestive hepatopathy.

Potent and biostable inhibitors of the main protease of SARS-CoV-2.

Potent and biostable inhibitors of the main protease (Mpro) of SARS-CoV-2 were designed and synthesized based on an active hit compound 5h (2). Our strategy was based not only on the introduction of fluorine atoms into the inhibitor molecule for an increase of binding affinity for the pocket of Mpro and cell membrane permeability but also on the replacement of the digestible amide bond by a surrogate structure to increase the biostability of the compounds. Compound 3 is highly potent and blocks SARS-CoV-2 infection in vitro without a viral breakthrough. The derivatives, which contain a thioamide surrogate in the P2-P1 amide bond of these compounds (2 and 3), showed remarkably preferable pharmacokinetics in mice compared with the corresponding parent compounds. These data show that compounds 3 and its biostable derivative 4 are potential drugs for treating COVID-19 and that replacement of the digestible amide bond by its thioamide surrogate structure is an effective method.

ETS1 governs pathological tissue-remodeling programs in disease-associated fibroblasts.

Fibroblasts, the most abundant structural cells, exert homeostatic functions but also drive disease pathogenesis. Single-cell technologies have illuminated the shared characteristics of pathogenic fibroblasts in multiple diseases including autoimmune arthritis, cancer and inflammatory colitis. However, the molecular mechanisms underlying the disease-associated fibroblast phenotypes remain largely unclear. Here, we identify ETS1 as the key transcription factor governing the pathological tissue-remodeling programs in fibroblasts. In arthritis, ETS1 drives polarization toward tissue-destructive fibroblasts by orchestrating hitherto undescribed regulatory elements of the osteoclast differentiation factor receptor activator of nuclear factor-κB ligand (RANKL) as well as matrix metalloproteinases. Fibroblast-specific ETS1 deletion resulted in ameliorated bone and cartilage damage under arthritic conditions without affecting the inflammation level. Cross-tissue fibroblast single-cell data analyses and genetic loss-of-function experiments lent support to the notion that ETS1 defines the perturbation-specific fibroblasts shared among various disease settings. These findings provide a mechanistic basis for pathogenic fibroblast polarization and have important therapeutic implications.