Journal of Clinical Investigation最新文献

Mycobacterium tuberculosis causes human tuberculosis. As mycobacteria are protected by thick lipid cell wall, humans have developed immune responses against diverse mycobacterial lipids. Most of these immunostimulatory lipids are known as adjuvants acting through innate immune receptors, such as C-type lectin receptors. Although a few mycobacterial lipid antigens activate unconventional T cells, antigenicity of most adjuvantic lipids are unknown. Here, we identified that trehalose monomycolate (TMM), an abundant mycobacterial adjuvant, activates human T cells bearing a unique ɑβTCR. This recognition was restricted by CD1b, a monomorphic antigen-presenting molecule conserved in primates but not mice. Single-cell TCR-RNA sequencing using newly established CD1b-TMM tetramers revealed that TMM-specific T cells are present as CD4+ effector memory T cells in the periphery of uninfected donors, but express IFNγ, TNF and anti-mycobacterial effectors upon TMM stimulation. TMM-specific T cells are detected in cord blood and PBMCs of non-BCG-vaccinated donors, but are expanded in active tuberculosis patients. A cryo-electron microscopy study of CD1b-TMM-TCR complexes revealed unique antigen recognition by conserved features of TCRs, positively-charged CDR3ɑ and long CDR3β regions. These results indicate that humans have a commonly-shared and pre-formed CD4+ T cell subset recognizing a typical mycobacterial adjuvant as an antigen. Furthermore, the dual role of TMM justifies reconsideration of the mechanism of action of adjuvants.

PARP inhibitors (PARPi) have received regulatory approval for the treatment of several tumors, including prostate cancer (PCa), and demonstrate remarkable results in the treatment of castration-resistant prostate cancer (CRPC) patients characterized by defects in homologous recombination repair (HRR) genes. Preclinical studies showed that DNA repair genes (DRG) other than HRR genes may have therapeutic value in the context of PARPi. To this end, we performed multiple CRISPR/Cas9 screens in PCa cell lines using a custom sgRNA library targeting DRG combined with PARPi treatment. We identified LIG1, EME1, and FAAP24 losses as PARPi sensitizers and assessed their frequencies from 3 to 6% among CRPC patients. We showed that concomitant inactivation of LIG1 and PARP induced replication stress and DNA double-strand breaks, ultimately leading to apoptosis. This synthetic lethality (SL) is conserved across multiple tumor types (e.g., lung, breast, and colorectal), and its applicability might be extended to LIG1-functional tumors through a pharmacological combinatorial approach. Importantly, the sensitivity of LIG1-deficient cells to PARPi was confirmed in vivo. Altogether, our results argue for the relevance of determining the status of LIG1, and potentially other non-HRR DRG for CRPC patient stratification and provide evidence to expand their therapeutic options.

KRAS is the most frequently mutated oncogene in lung adenocarcinoma, with G12C and G12V being the most predominant forms. Recent breakthroughs in KRASG12C inhibitors have transformed the clinical management of patients with G12C mutation and advanced our understanding of its function. However, little is known about the targeted disruption of KRASG12V, partly due to a lack of specific inhibitors. Here, we leverage the degradation tag (dTAG) system to develop a KRASG12V transgenic mouse model. We explore the therapeutic potential of KRASG12V degradation and characterize its impact on the tumor microenvironment (TME). Our study reveals that degrading KRASG12V abolishes lung and pancreatic tumors in mice and causes a robust inhibition of KRAS-regulated cancer intrinsic signaling. Importantly, targeted degradation of KRASG12V reprograms the TME towards a stimulatory milieu and drives antitumor immunity, elicited mainly by effector and cytotoxic CD8+ T cells. Our work provides important insights into the impact of degrading KRASG12V on both tumor progression and immune response, highlighting degraders as a powerful strategy for targeting KRAS mutant cancers.

Understanding cell fate regulation in the liver is necessary to advance cell therapies for hepatic disease. Liver progenitor cells (LPC) contribute to tissue regeneration after severe hepatic injury yet signals instructing progenitor cell dynamics and fate are largely unknown. The Tissue Inhibitor of Metalloproteinases, TIMP1 and TIMP3 control the sheddases ADAM10 and ADAM17, key for NOTCH activation. Here we uncover the role of the TIMP/ADAM/NOTCH/DLK1 axis in LPC maintenance and cholangiocyte specification. Combined TIMP1/TIMP3 loss in vivo caused abnormal portal triad stoichiometry accompanied by collagen deposits, dysregulated Notch signalling and increased soluble DLK1. The MIC1-1C3+CD133+CD26- biliary progenitor population was reduced following acute CCl4 or chronic DDC liver injury and in aged TIMP deficient livers. ScRNA-seq data interrogation and RNAscope identified portal mesenchymal cells co-expressing ADAM17/DLK1 as enzymatically equipped to process DLK1 and direct LPC differentiation. Specifically, TIMP deficient biliary fragment-derived organoids displayed increased propensity for cholangiocyte differentiation. ADAM17 inhibition reduced Sox9-mediated cholangiocyte differentiation, prolonging organoid growth and survival, whereas soluble DLK1-treated WT organoids triggered Sox9 expression and cholangiocyte specification in mouse and patient-derived liver organoids. Thus, metalloprotease inhibitors regulate instructive signals for biliary cell differentiation and LPC preservation within the portal niche, providing a new basis for cell therapy strategies.

Parkinson's disease (PD) is the second most prevalent neurodegenerative disorder. While there is no curative treatment, the immune system's involvement with autoimmune T cells that recognize the protein alpha-synuclein (α-syn) in a subset of individuals suggests new areas for therapeutic strategies. As not all patients with PD have T cells specific for α-syn, we explored additional autoantigenic targets of T cells in PD. We generated 15-mer peptides spanning several PD-related proteins implicated in PD pathology, including Glucosylceramidase Beta 1 (GBA), Superoxide dismutase 1 (SOD1), PTEN Induced Kinase 1 (PINK1), Parkin RBR E3 Ubiquitin Protein Ligase (parkin), Oxoglutarate Dehydrogenase (OGDH), and Leucine Rich Repeat Kinase 2 (LRRK2). Cytokine production (IFNγ, IL-5, IL-10) against these proteins was measured using a fluorospot assay and PBMCs from patients with PD and age-matched healthy controls. We identified PINK1, a regulator of mitochondrial stability, as an autoantigen targeted by T cells, as well as its unique epitopes, and their HLA restriction. The PINK1-specific T cell reactivity revealed sex-based differences as it was predominantly found in male patients with PD, which may contribute to the heterogeneity of PD. Identifying and characterizing PINK1 and other autoinflammatory targets may lead to antigen-specific diagnostics, progression markers, and/or novel therapeutic strategies for PD.

Heterozygous truncating variants in the sarcomere protein titin (TTN) are the most common genetic cause of heart failure. To understand mechanisms that regulate abundant cardiomyocyte TTN expression we characterized highly conserved intron 1 sequences that exhibited dynamic changes in chromatin accessibility during differentiation of human cardiomyocytes from induced pluripotent stem cells (hiPSC-CMs). Homozygous deletion of these sequences in mice caused embryonic lethality while heterozygous mice demonstrated allele-specific reduction in Ttn expression. A 296 bp fragment of this element, denoted E1, was sufficient to drive expression of a reporter gene in hiPSC-CMs. Deletion of E1 downregulated TTN expression, impaired sarcomerogenesis, and decreased contractility in hiPSC-CMs. Site-directed mutagenesis of predicted NKX2-5- and MEF2-binding sites within E1 abolished its transcriptional activity. Embryonic mice expressing E1 reporter gene constructs validated in vivo cardiac-specific activity of E1 and the requirement for NKX2-5 and MEF2 binding sequences. Moreover, isogenic hiPSC-CMs containing a rare E1 variant in the predicted MEF2 binding motif that was identified in a patient with unexplained DCM showed reduced TTN expression. Together these discoveries define an essential, functional enhancer that regulates TTN expression. Manipulation of this element may advance therapeutic strategies to treat DCM caused by TTN haploinsufficiency.

Vitamin D regulates mineral homeostasis. The most biologically active form of vitamin D, 1,25-dihydroxyvitamin D (1,25D), is synthesized by CYP27B1 from 25-dihydroxyvitamin D (25D) and inactivated by CYP24A1. Human monogenic diseases and genome-wide association studies support a critical role for CYP24A1 in regulation of mineral homeostasis, but little is known about its tissue-specific effects. Here, we describe the responses of mice with inducible global deletion, kidney-specific, and intestine-specific deletion of Cyp24a1 to dietary calcium challenge and chronic kidney disease (CKD). Global and kidney-specific Cyp24a1 deletion caused similar syndromes of systemic vitamin D intoxication: elevated circulating 1,25D, 25D and fibroblast growth factor 23 (FGF23), activation of vitamin D target genes in the kidney and intestine, hypercalcemia, and suppressed parathyroid hormone (PTH). In contrast, mice with intestine-specific Cyp24a1 deletion demonstrated activation of vitamin D target genes exclusively in the intestine despite no changes in systemic vitamin D levels. In response to a high calcium diet, PTH was suppressed despite normal serum calcium. In mice with CKD, intestinal Cyp24a1 deletion decreased PTH and FGF23 without precipitating hypercalcemia. These results implicate kidney CYP24A1 in systemic vitamin D regulation while independent local effects of intestinal CYP24A1 could be targeted to treat secondary hyperparathyroidism in CKD.

Various factors play key roles in maintaining intestine homeostasis. Disruption of the balance may lead to intestinal inflammatory diseases (IBDs) and even colorectal cancer (CRC). Loss or gain of function of many key proteins can result in dysregulated intestinal homeostasis. Our research demonstrated that neural precursor cells expressed developmentally down-regulated 4-like protein, NEDD4L (NEDD4-2), a type of HECT family E3 ubiquitin ligase, played an important role in maintaining intestinal homeostasis. NEDD4L expression was significantly inhibited in intestinal epithelial cells (IECs) of patients with Crohn's disease (CD), ulcerative colitis (UC), and CRC. Global knockout of NEDD4L or its deficiency in IECs exacerbated dextran sulfate sodium (DSS)-/2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis and azoxymethane (AOM)/DSS-induced colorectal cancer. Mechanistically, NEDD4L deficiency in IECs inhibited the key ferroptosis regulator glutathione peroxidase 4 (GPX4) expression by reducing the protein expression of solute carrier family 3 member 2 (SLC3A2) without affecting its gene expression, ultimately promoting DSS-induced IEC ferroptosis. Importantly, ferroptosis inhibitors reduced the susceptibility of NEDD4L-deficient mice to colitis and colitis-associated colorectal cancer (CAC). Thus, NEDD4L was an important regulator in IEC ferroptosis, maintaining intestinal homeostasis, making it a potential clinical target for diagnosing and treating IBDs.

The occurrence of aging is intricately associated with alterations in circadian rhythms that coincide with stem cell exhaustion. Nonetheless, the extent to which the circadian system governs skeletal aging remains inadequately understood. Here, we noticed that skeletal aging in male mice was accompanied by a decline in a core circadian protein, BMAL1, especially in bone marrow endothelial cells (ECs). Using male mice with endothelial KO of aryl hydrocarbon receptor nuclear translocator-like protein 1 (Bmal1), we ascertained that endothelial BMAL1 in bone played a crucial role in ensuring the stability of an extracellular structural component, fibrillin-1 (FBN1), through regulation of the equilibrium between the extracellular matrix (ECM) proteases thrombospondin type 1 domain-containing protein 4 (THSD4) and metalloproteinase with thrombospondin motifs 4 (ADAMTS4), which promote FBN1 assembly and breakdown, respectively. The decline of endothelial BMAL1 during aging prompted excessive breakdown of FBN1, leading to persistent activation of TGF-β/SMAD3 signaling and exhaustion of bone marrow mesenchymal stem cells. Meanwhile, the free TGF-β could promote osteoclast formation. Further analysis revealed that activation of ADAMTS4 in ECs lacking BMAL1 was stimulated by TGF-β/SMAD3 signaling through an ECM-positive feedback mechanism, whereas THSD4 was under direct transcriptional control by endothelial BMAL1. Our investigation has elucidated the etiology of bone aging in male mice by defining the role of ECs in upholding the equilibrium within the ECM, consequently coordinating osteogenic and osteoclastic activities and retarding skeletal aging.