Journal of Experimental Medicine最新文献

Inhibition of the proximal B cell receptor (BCR) signaling pathway by BTK inhibitors is highly effective in the treatment of CLL, but drug resistance or intolerance occurs. Here, we investigated c-Jun N-terminal protein kinase 1 (JNK1) as an alternative drug target in the distal BCR pathway. JNK1 was preferentially overexpressed and activated in poor prognostic CLL with unmutated IGHV. Proximal BCR inhibition (BTK, PI3K, or SYK inhibitors) or SYK knockdown efficiently dephosphorylated JNK1, identifying JNK1 as a critical BCR downstream kinase in CLL. JNK1 inhibition induced apoptosis in primary CLL cells, resulting in the downregulation of BCL2, MCL1, and c-JUN. JNK1 inhibition in patient-derived CLL xenografted mice and Eµ-TCL1-tg mice prevented CLL progression, reduced splenic infiltration, and restored T cell function and normal hematopoiesis. JNK1 inhibitors even remained effective in ibrutinib refractory CLL. In conclusion, our study revealed JNK1 as a promising drug target in CLL downstream of the BCR, overcoming ibrutinib resistance, blocking the protective microenvironment, and improving CLL-specific immunosuppressive mechanisms.

The molecular mechanism by which inborn errors of the human RNA lariat-debranching enzyme 1 (DBR1) underlie brainstem viral encephalitis is unknown. We show here that the accumulation of RNA lariats in human DBR1-deficient cells interferes with stress granule (SG) assembly, promoting the proteasome degradation of at least G3BP1 and G3BP2, two key components of SGs. In turn, impaired assembly of SGs, which normally recruit PKR, impairs PKR activation and activity against viruses, including HSV-1. Remarkably, the genetic ablation of PKR abolishes the corresponding antiviral effect of DBR1 in vitro. We also show that Dbr1Y17H/Y17H mice are susceptible to similar viral infections in vivo. Moreover, cells and brain samples from Dbr1Y17H/Y17H mice exhibit decreased G3BP1/2 expression and PKR phosphorylation. Thus, the debranching of RNA lariats by DBR1 permits G3BP1/2- and SG assembly-mediated PKR activation and cell-intrinsic antiviral immunity in mice and humans. DBR1-deficient patients are prone to viral disease because of intracellular lariat accumulation, which impairs G3BP1/2- and SG assembly-dependent PKR activation.

Somatic variants accumulate in all organs with age, with a positive selection of clonal populations that provide a fitness advantage during times of heightened cellular stress leading to clonal expansion. Easily measured within the hematopoietic compartment, clonal hematopoiesis (CH) is now recognized as a common process in which hematopoietic clones with somatic variants associated with hematopoietic neoplasms exist within the blood or bone marrow of individuals without evidence of malignancy. Most cases of CH involve a limited number of genes, most commonly DNMT3A, TET2, and ASXL1. CH confers risk for solid and hematopoietic malignancies as well as cardiovascular and numerous inflammatory diseases and offers opportunities for cancer prevention. Here, we explore the genetic and environmental factors that predispose individuals to CH with unique variant signatures and discuss how CH drives cancer progression with the goals of improving individual cancer risk stratification, identifying key intervention opportunities, and understanding how CH impacts therapeutic strategies and outcomes.

Immunotherapy-related colitis (irC) frequently emerges as an immune-related adverse event during immune checkpoint inhibitor therapy and is presumably influenced by the gut microbiota. We longitudinally studied microbiomes from 38 ICI-treated cancer patients. We compared 13 ICI-treated subjects who developed irC against 25 ICI-treated subjects who remained irC-free, along with a validation cohort. Leveraging a preclinical mouse model, predisease stools from irC subjects induced greater colitigenicity upon transfer to mice. The microbiota during the first 10 days of irC closely resembled inflammatory bowel disease microbiomes, with reduced diversity, increased Proteobacteria and Veillonella, and decreased Faecalibacterium, which normalized before irC remission. These findings highlight the irC gut microbiota as functionally distinct but phylogenetically similar to non-irC and healthy microbiomes, with the exception of an acute, transient disruption early in irC. We underscore the significance of longitudinal microbiome profiling in developing clinical avenues to detect, monitor, and mitigate irC in ICI therapy cancer patients.

CD206 is a common marker of a putative immunosuppressive "M2" state in tumor-associated macrophages (TAMs). We made a novel conditional CD206 (Mrc1) knock-in mouse to specifically visualize and/or deplete CD206+ TAMs. Early depletion of CD206+ macrophages and monocytes (Mono/Macs) led to the indirect loss of conventional type I dendritic cells (cDC1), CD8 T cells, and NK cells in tumors. CD206+ TAMs robustly expressed CXCL9, contrasting with stress-responsive Spp1-expressing TAMs and immature monocytes, which became prominent with early depletion. CD206+ TAMs differentially attracted activated CD8 T cells, and the NK and CD8 T cells in CD206-depleted tumors were deficient in Cxcr3 and cDC1-supportive Xcl1 and Flt3l expressions. Disrupting this key antitumor axis decreased tumor control by antigen-specific T cells in mice. In human cancers, a CD206Replete, but not a CD206Depleted Mono/Mac gene signature correlated robustly with CD8 T cell, cDC1, and NK signatures and was associated with better survival. These findings negate the unqualified classification of CD206+ "M2-like" macrophages as immunosuppressive.

The cohesin complex is a critical regulator of gene expression. STAG2 is the most frequently mutated cohesin subunit across several cancer types and is a key tumor suppressor in lung cancer. Here, we coupled somatic CRISPR-Cas9 genome editing and tumor barcoding with an autochthonous oncogenic KRAS-driven lung cancer model and showed that STAG2 is uniquely tumor-suppressive among all core and auxiliary cohesin components. The heterodimeric complex components PAXIP1 and PAGR1 have highly correlated effects with STAG2 in human lung cancer cell lines, are tumor suppressors in vivo, and are epistatic to STAG2 in oncogenic KRAS-driven lung tumorigenesis in vivo. STAG2 inactivation elicits changes in gene expression, chromatin accessibility, and 3D genome conformation that impact the cancer cell state. Gene expression and chromatin accessibility similarities between STAG2- and PAXIP1-deficient neoplastic cells further relate STAG2-cohesin to PAXIP1/PAGR1. These findings reveal a STAG2-PAXIP1/PAGR1 tumor-suppressive axis and uncover novel PAXIP1-dependent and PAXIP1-independent STAG2-cohesin-mediated mechanisms of lung tumor suppression.

Terez Shea-Donohue is the program director of the Division of Digestive Diseases and Nutrition at the National Institute of Diabetes and Digestive and Kidney Diseases of the National Institutes of Health. As a program director, Terez supports basic and translational research related to neurogastroenterology, gastrointestinal (GI), and GI epithelial barrier function. We spoke to Terez about the transition from active research to a predominantly administrative job, the need for life-long mentorship, and the continued sex/gender bias in health care.

Two complementary works by Chan et al. (https://doi.org/10.1084/jem.20231725), and Ru et al. (https://doi.org/10.1084/jem.20240010), identify defective RNA processing as the root cause of impaired antiviral immunity against SARS-CoV2 in the human brainstem. These studies provide molecular insight into virus-associated severe brainstem encephalitis through PKR inactivation.

In this issue of JEM, Robles-Oteiza et al. (https://doi.org/10.1084/jem.20231106) present compelling evidence linking tumor hypoxia to acquired resistance mechanisms in non-small cell lung cancer (NSCLC) treatments involving immune checkpoint inhibitors (ICIs). Their research advocates targeting these hypoxic tumor regions with hypoxia-activated pro-drugs like TH-302, which may substantially delay the onset of resistance and herald a significant advancement in cancer therapy.

The role of microbes and their metabolites in modulating tuft cell (TC) dynamics in the large intestine and the relevance of this pathway to infections is unknown. Here, we uncover that microbiome-driven colonic TC hyperplasia protects against Clostridioides difficile infection. Using selective antibiotics, we demonstrate increased type 2 cytokines and TC hyperplasia in the colon but not in the ileum. We demonstrate the causal role of the microbiome in modulating this phenotype using fecal matter transplantation and administration of consortia of succinate-producing bacteria. Administration of succinate production-deficient microbes shows a reduced response in a Pou2f3-dependent manner despite similar intestinal colonization. Finally, antibiotic-treated mice prophylactically administered with succinate-producing bacteria show increased protection against C. difficile-induced morbidity and mortality. This effect is nullified in Pou2f3-/- mice, confirming that the protection occurs via the TC pathway. We propose that activation of TCs by the microbiota in the colon is a mechanism evolved by the host to counterbalance microbiome-derived cues that facilitate invasion by pathogens.