Abstract
Human γδ T cells are a rare but functionally diverse lymphocyte subset critical for tumor surveillance and antimicrobial immunity. Although they express NK cell–associated receptors such as killer-cell immunoglobulin-like receptors (KIRs), the relevance of KIR expression on γδ T cells remains largely unexplored. Using flow cytometry, ATAC-seq, and RNA-seq, we identified KIR expression as a marker that distinguished 2 functionally and molecularly distinct γδ T cell subsets. KIR+ γδ T cells exhibited an advanced, memory-like differentiation state characterized by heightened cytotoxicity, stable epigenetic remodeling, and a predominant IFN-γ–producing profile. In contrast, KIR– γδ T cells maintained a naive-like phenotype and preferentially produced IL-17 upon polarization. Notably, KIR+ γδ T cells were consistently observed across individuals but were significantly enriched in cytomegalovirus (CMV)-seropositive donors, suggesting that chronic antigenic stimulation could promote the emergence of KIR+ effector γδ T cells. These findings reveal a functional dichotomy in human γδ T cells defined by KIR expression, linking IFN-γ–driven cytotoxicity with KIR+ cells and IL-17 production with KIR– cells. This insight advances our understanding of γδ T cell heterogeneity and has implications for viral immunity, immune memory, and the development of γδ T cell–based immunotherapies.
Authors
Mahya Razmi, Yeganeh Almasi, Marilee Larrivée, Jonathan B. Angel, Alexandre Blais, Zakia Djaoud
Abstract
Natural killer (NK) cells are pivotal in the early immune response to Plasmodium falciparum infection, yet their functional dynamics and regulation remain incompletely understood. In a longitudinal study of patients with malaria in a nonendemic setting, we observed a transient but potent activation of NK cell cytotoxicity during acute malaria, characterized by rapid granzyme B–mediated killing and elevated expression of genes associated with cytotoxicity (PRF1, GZMB, and GZMA). This heightened activity was supported by increased plasma levels of granzymes and proinflammatory cytokines, which enhanced NK cell function in vitro. However, plasma samples from clinical malaria also contained inhibitory mediators, including soluble cytokine receptors, which dampened NK cell responses. These findings reveal that the host microenvironment orchestrates a tightly regulated NK cell response that potentiates cytotoxicity during acute infection and rapidly downmodulates it after treatment. Understanding this balance between activation and suppression may inform strategies to harness NK cells for malaria control while minimizing immunopathology.
Authors
Pengjun Xi, Patrick A. Sandoz, Maximilian Julius Lautenbach, Eleni Bilev, Björn Önfelt, Anna Färnert, Quirin Hammer, Christopher Sundling
Abstract
Mixed hematopoietic chimerism after hematopoietic cell transplantation (HCT) can modulate the immune system and induce tolerance to allogeneic tissues. However, bone marrow conditioning–related toxicities preclude wider adoption of HCT for transplant allotolerance. We sought agents that reduced conditioning intensity, while promoting durable mixed chimerism after HCT across complete MHC mismatch in diabetic mice, permitting islet allotransplantation and diabetes reversal. We systematically tested baricitinib (JAK1/2 inhibitor), venetoclax (Bcl-2 inhibitor), and CD47 antibody, agents in current clinical use, and quantified hematopoietic chimerism after HCT. Combined with CD117 antibody, transient T cell depletion, and just 10 centigray total body irradiation, these agents enabled durable mixed chimerism and matching alloislet tolerance to cure diabetes without evidence of graft-versus-host disease. Thus, we have developed a conditioning regimen to promote allogeneic mixed hematopoietic chimerism and transplanted islet allotolerance that minimizes conditioning radiation and cures diabetes.
Authors
Stephan A. Ramos, Preksha Bhagchandani, Diego M. Burgos, Xueying Gu, Richard Rodriguez, Nadia Nourin, Martin Neukam, Shiva Pathak, Judith A. Shizuru, Seung K. Kim
Abstract
Aortic dissection (AD) is a catastrophic vascular emergency with high mortality, and current pharmacological interventions to prevent its progression are limited. Vascular smooth muscle cells (VSMCs) undergo a pathological phenotypic switch from a contractile to a synthetic state during AD, compromising aortic wall integrity; however, the underlying metabolic mechanisms remain poorly understood. In this study, we performed integrative transcriptomic analyses and identified glutaminase 1 (GLS1) as a key regulator of VSMC phenotypic switching in AD. GLS1 expression was significantly downregulated in VSMCs from both human AD aortic tissues and mouse models. Functionally, GLS1 deficiency promoted PDGF-BB–induced VSMC dedifferentiation in vitro. Smooth muscle cell–specific Gls1-knockout (Gls1SMKO) mice exhibited aggravated AD after β-aminopropionitrile treatment, whereas VSMC-specific GLS1 overexpression improved the contractile phenotype and reduced AD incidence. Mechanistically, GLS1 downregulation impaired glutamate metabolism, leading to reduced levels of glutathione and α-ketoglutarate. This metabolic disruption promoted reactive oxygen species accumulation and mitochondrial dysfunction, ultimately triggering VSMC phenotypic switching. Furthermore, we found that GLS1 transcription was repressed by retinoic acid receptor-α (RARα). Pharmacological inhibition of RARα with AR7 restored GLS1 expression, ameliorated VSMC phenotypic switching, and conferred protection against AD. These findings reveal a critical role of GLS1-mediated glutamate metabolism in VSMC phenotypic switching and suggest a promising therapeutic strategy for AD.
Authors
Wei Xie, Chen Ning, Chen Lu, Dongjin Wang, Shuang Zhao, Tianyu Song, Hailong Cao
Abstract
Hypothalamic melanocortin 4 receptors (MC4Rs) play a central role in regulating food intake and energy homeostasis. In fact, inactivating mutations in the MC4R gene are the most common form of monogenic obesity. Agonist activation of MC4Rs reduces food intake by modulating hypothalamic signaling circuits. Thus, a detailed understanding of the signaling pathways that regulate MC4R activity is of considerable translational relevance. Ligand-activated MC4Rs not only interact with heterotrimeric G proteins but also can recruit β-arrestin-2 (barr2) to the receptor. The potential functional role of barr2 in regulating the anorectic effects of MC4R signaling remains unexplored. In the present study, we used mutant mouse models to demonstrate MC4R-mediated activation of barr2/ERK signaling in MC4R neurons of the paraventricular nucleus leads to reduced food intake. We also found the appetite-suppressing effect of setmelanotide, an MC4R agonist FDA approved for the treatment of certain types of obesity, requires the presence of barr2 in MC4R-containing neurons. These data suggest that MC4R agonists able to promote MC4R/barr2 interactions with high efficacy may become useful as appetite-suppressing drugs.
Authors
Misbah Rashid, Lei Wang, Zhenzhong Cui, Oksana Gavrilova, Huiyan Lu, Kozo Kaibuchi, Sarah Zeitlmayr, Thomas Gudermann, Andreas Breit, Jürgen Wess
Abstract
The RhoBTB1/Cullin-3 (CUL3) pathway in smooth muscle cells (SMCs) controls the ubiquitination and proteasomal degradation of target proteins that regulate vasodilation, vasoconstriction, and the actin cytoskeleton and, through this, blood pressure (BP) and arterial stiffness. Using proximity labeling coupled with mass spectrometry in A7R5 SMCs, we identified proteins that bound to the C-terminal half of RhoBTB1, which functions as an adaptor to deliver substrates to CUL3. We examined the physiological relevance of one of these substrates, RbFox2. Coimmunoprecipitation validated the interaction of RbFox2 with RhoBTB1. RbFox2 expression was elevated in response to inhibition of the ubiquitination-proteasomal pathway, CUL3 deficiency, and RhoBTB1 inhibition by either siRNA or angiotensin II (ANG). RbFox2 was ubiquitinated in a RhoBTB1- and CUL3-dependent manner, suggesting its regulation through the RhoBTB1/CUL3-dependent ubiquitin-proteasome pathway. Inhibition of RbFox2 impaired the actin cytoskeleton in A7R5 cells and in primary SMCs from RbFox2fl/fl mice and decreased the levels of globular and filamentous actin. ANG increased BP and arterial stiffness of RbFox2fl/fl mice, but the progression of arterial stiffness was halted after SMC-specific RbFox2 deletion despite a continued rise in BP. We conclude that RhoBTB1 and RbFox2 are important regulators of arterial stiffness through a mechanism that influences cytoskeletal integrity.
Authors
Gaurav Kumar, Nisita Chaihongsa, Daniel T. Brozoski, Daria Golosova, Ibrahim Vazirabad, Ko-Ting Lu, Kelsey K. Wackman, Ravi K. Singh, Curt D. Sigmund
Abstract
Increased consumption of ultra-processed foods (UPFs) is a risk factor for metabolic disorder–associated heart failure (HF). Here, we demonstrate that UPF-induced calpain-1 aggravated oxidative stress, thereby increasing high mobility group box 1–mediated (HMGB1-mediated) myocardial inflammation, which contributes to cardiac dysfunction. After illustrating the dysregulated inflammatory pathways in human and murine hearts upon metabolic stress, we revealed an increase in calpain-1 alongside profound oxidative stress and inflammation in the failing myocardium. Mechanistically, in neonatal rat cardiomyocytes and human induced pluripotent stem cell–derived cardiomyocytes, HMGB1 was upregulated by calpain-1 and reactive oxygen species (ROS) upon stress of saturated and trans fatty acids. Consequently, HMGB1 promoted a proinflammatory response in macrophages. In contrast, inhibition of calpain or ROS efficiently repressed HMGB1 in cardiomyocytes. Therapeutically, either recombinant adeno-associated virus 9–delivered inhibitor of calpain-1 or its pharmacological inhibitor attenuated ROS and HMGB1-induced inflammation in the myocardium and mitigated HF in both male and female mice fed with an ultra-processed diet. Collectively, we have demonstrated the effects of suppressing calpain-1 and oxidative stress on alleviating myocardial inflammation via blockage of HMGB1 and cardiac dysfunction. The results provide a promising therapeutic strategy for preventing or treating HF in metabolic disorders.
Authors
Claire Ross, Sanskruti Ravindra Gare, Nasser H.O. Alatawi, Oveena Fonseka, Xinyi Chen, Jiayan Zhang, Yihua Han, Andrea Ruiz-Velasco, Riham R.E. Abouleisa, Yingjuan Liu, Xiangjun Zhao, Han Xiao, Bernard D. Keavney, Gareth J. Howell, Tao Wang, Tamer M.A. Mohamed, Elizabeth J. Cartwright, Wei Liu
Abstract
Sepsis is a leading cause of death for which host-directed therapies are urgently needed. We performed high-dimensional flow cytometry, measurement of soluble biomarkers, and lipopolysaccharide (LPS) stimulation of neutrophils to characterize neutrophil heterogeneity and function in patients with sepsis. We observed that in patients with sepsis, low-density neutrophils (LDNs) are elevated and phenotypically diverse populations of innate immune cells with varying degrees of maturity and myeloperoxidase expression. Spleen tyrosine kinase (SYK) expression was found to be higher in whole blood neutrophils and LDNs of patients with sepsis compared with healthy donors. Importantly, SYK+ LDNs associated with increased levels of intracellular myeloperoxidase (MPO) and soluble biomarkers. Furthermore, SYK+ LDNs correlated with clinical outcomes of sepsis disease severity, including sequential organ failure assessment score, mechanical ventilation, and vasopressors. Functionally, the SYK inhibitor R406 suppressed changes in neutrophil features of activation from normal-density neutrophils and LDNs, including the SYK+ and SYK– neutrophil subsets, and MPO release from LDNs following LPS stimulation of sepsis neutrophils. Combined, these results establish LDNs as a heterogenous population of neutrophils that express high levels of SYK and support SYK inhibition as a potentially novel therapeutic target aimed at suppressing overactive neutrophils in sepsis.
Authors
Heather L. Teague, Lauren Knabe, Raquel S. Da Cruz, Xianglan Yao, Kiana C. Allen, Trenton Williams, Cumhur Y. Demirkale, Merte Woldehanna, Ernest Evans, Amir Hobson, Jared D. Wilkinson, Steven D. Nathan, Christopher S. King, Jeffrey R. Strich
Abstract
Fibroblast-like synoviocytes (FLSs) are crucial in driving synovial inflammation and joint damage in rheumatoid arthritis (RA). This study explored the functions and underlying mechanisms of GALNT1-mediated O-glycosylation, which is markedly upregulated in RA FLSs, in synovial aggression and subsequent experimental joint damage. Targeted suppression of GALNT1 effectively curtailed migration and invasion in RA FLSs and mitigated arthritis severity in a collagen-induced arthritis model in rats. Mechanistically, NEK9 was identified as a pivotal substrate and downstream effector of GALNT1, affecting the aggressive phenotype of RA FLSs. In vitro experiments further demonstrated that O-glycosylation of NEK9, mediated by GALNT1, promotes the pathogenic phenotype of RA FLSs by promoting cytoskeleton reorganization and restraining excessive ER stress activation. Our study provides mechanistic insights into the activation of RA FLSs and identifies GALNT1 as a potential therapeutic target for RA.
Authors
Yaoyao Zou, Haobo Lin, Jianling Su, Jieying Wang, Qin Zeng, Tianxiao Feng, Yunxia Lei, Jianda Ma, Hudan Pan, Hanshi Xu, Lie Dai, Yang Li
Abstract
Inactivating NOTCH1 mutations in head and neck squamous cell carcinoma (HNSCC) were described over a decade ago, suggesting a tumor suppressor function — unlike its oncogenic role in other tumors. Today, much debate persists regarding a putative oncogenic role in HNSCC as well, with reports that NOTCH1 signaling drives tumor growth and a cancer stem cell (CSC) phenotype. In this work, comprehensive experiments unequivocally demonstrate that NOTCH1 is a tumor suppressor in HNSCC regardless of mutation or activation status and that it reduces CSC frequency. We developed a signature of NOTCH1 activation showing the pathway is associated with very early differentiation, an altered tumor microenvironment, and better prognosis. Clarifying whether NOTCH1 occasionally functions as an oncogenic driver in HNSCC is crucial to prognosis and personalized therapy. The results presented unify the field, reconcile conflicting data, and provide critical insights into the biological and clinical significance of NOTCH1, with broader implications in other squamous carcinomas with NOTCH1 mutations.
Authors
Chenfei Huang, Shhyam Moorthy, Qiuli Li, Kazi M. Ahmed, Kalil Saab, Defeng Deng, Jiping Wang, Xiayu Rao, Jiexin Zhang, Yuanxin Xi, Jing Wang, Zhiyi Liu, Noriaki Tanaka, David A. Wheeler, Eve Shinbrot, Rami Saade, Curtis R. Pickering, Tong-Xin Xie, Adel K. El-Naggar, Abdullah A. Osman, Kunal Rai, Patrick A. Zweidler-McKay, John V. Heymach, Lauren A. Byers, Faye M. Johnson, Vlad C. Sandulache, Jeffrey N. Myers, Pedram Yadollahi, Mitchell J. Frederick
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