The mechanisms that drive T cell aging are not understood. We report that children and adult telomerase mutation carriers with short telomere length (TL) develop a T cell immunodeficiency that can manifest in the absence of bone marrow failure and causes life-threatening opportunistic infections. Mutation carriers shared T cell–aging phenotypes seen in adults 5 decades older, including depleted naive T cells, increased apoptosis, and restricted T cell repertoire. T cell receptor excision circles (TRECs) were also undetectable or low, suggesting that newborn screening may identify individuals with germline telomere maintenance defects. Telomerase-null mice with short TL showed defects throughout T cell development, including increased apoptosis of stimulated thymocytes, their intrathymic precursors, in addition to depleted hematopoietic reserves. When we examined the transcriptional programs of T cells from telomerase mutation carriers, we found they diverged from older adults with normal TL. Short telomere T cells upregulated DNA damage and intrinsic apoptosis pathways, while older adult T cells upregulated extrinsic apoptosis pathways and programmed cell death 1 (PD-1) expression. T cells from mice with short TL also showed an active DNA-damage response, in contrast with old WT mice, despite their shared propensity to apoptosis. Our data suggest there are TL-dependent and TL-independent mechanisms that differentially contribute to distinct molecular programs of T cell apoptosis with aging.
Christa L. Wagner, Vidya Sagar Hanumanthu, C. Conover Talbot Jr., Roshini S. Abraham, David Hamm, Dustin L. Gable, Christopher G. Kanakry, Carolyn D. Applegate, Janet Siliciano, J. Brooks Jackson, Stephen Desiderio, Jonathan K. Alder, Leo Luznik, Mary Armanios
Recombinant adeno-associated virus (AAV) vectors have been broadly adopted as a gene delivery tool in clinical trials, owing to their high efficiency of transduction of several host tissues and their low immunogenicity. However, a considerable proportion of the population is naturally exposed to the WT virus from which AAV vectors are derived, which leads to the acquisition of immunological memory that can directly determine the outcome of gene transfer. Here, we show that prior exposure to AAV drives distinct capsid immunity profiles in healthy subjects. In peripheral blood mononuclear cells (PBMCs) isolated from AAV-seropositive donors, recombinant AAV triggered TNF-α secretion in memory CD8+ T cells, B cell differentiation into antibody-secreting cells, and anti-capsid antibody production. Conversely, PBMCs isolated from AAV-seronegative individuals appeared to carry a population of NK cells reactive to AAV. Further, we demonstrated that the AAV capsid activates IL-1β and IL-6 cytokine secretion in monocyte-related dendritic cells (moDCs). IL-1β and IL-6 blockade inhibited the anti-capsid humoral response in vitro and in vivo. These results provide insights into immune responses to AAV in humans, define a possible role for moDCs and NK cells in capsid immunity, and open new avenues for the modulation of vector immunogenicity.
Klaudia Kuranda, Priscilla Jean-Alphonse, Christian Leborgne, Romain Hardet, Fanny Collaud, Solenne Marmier, Helena Costa Verdera, Giuseppe Ronzitti, Philippe Veron, Federico Mingozzi
Obesity and overnutrition increase levels of reactive sugar- and lipid-derived aldehydes called reactive carbonyl species (RCS). Increased tissue and circulating RCS levels have been tied to insulin resistance and inflammation, but previous pharmacological approaches to target RCS have had equivocal outcomes. In this issue of the JCI, Anderson et al. present evidence for the development and implementation of carnisonol, a compound that is biologically stable in vivo and shows impressive effects on improving metabolism and inflammation in rodent models of diet-induced obesity and metabolic dysfunction.
Jacob M. Haus, John P. Thyfault
Protein quality control (PQC) mechanisms are essential for maintaining cardiac function, and alterations in this pathway influence multiple forms of heart disease. Since heart disease is the leading cause of death worldwide, understanding how the delicate balance between protein synthesis and degradation is regulated in the heart demands attention. The study by Hu et al. reveals that the extraproteasomal ubiquitin receptor Ubiquilin1 (Ubqln1) plays an important role in cardiac ubiquitination-proteasome coupling, particularly in response to myocardial ischemia/reperfusion injury, thereby suggesting that this may be a new avenue for therapeutics.
Xi Fang, Christa Trexler, Ju Chen
Sugar- and lipid-derived aldehydes are reactive carbonyl species (RCS) frequently used as surrogate markers of oxidative stress in obesity. A pathogenic role for RCS in metabolic diseases of obesity remains controversial, however, partly because of their highly diffuse and broad reactivity and the lack of specific RCS-scavenging therapies. Naturally occurring histidine dipeptides (e.g., anserine and carnosine) show RCS reactivity, but their therapeutic potential in humans is limited by serum carnosinases. Here, we present the rational design, characterization, and pharmacological evaluation of carnosinol, i.e., (2S)-2-(3-amino propanoylamino)-3-(1H-imidazol-5-yl)propanol, a derivative of carnosine with high oral bioavailability that is resistant to carnosinases. Carnosinol displayed a suitable ADMET (absorption, distribution, metabolism, excretion, and toxicity) profile and was determined to have the greatest potency and selectivity toward α,β-unsaturated aldehydes (e.g., 4-hydroxynonenal, HNE, ACR) among all others reported thus far. In rodent models of diet-induced obesity and metabolic syndrome, carnosinol dose-dependently attenuated HNE adduct formation in liver and skeletal muscle, while simultaneously mitigating inflammation, dyslipidemia, insulin resistance, and steatohepatitis. These improvements in metabolic parameters with carnosinol were not due to changes in energy expenditure, physical activity, adiposity, or body weight. Collectively, our findings illustrate a pathogenic role for RCS in obesity-related metabolic disorders and provide validation for a promising new class of carbonyl-scavenging therapeutic compounds rationally derived from carnosine.
Ethan J. Anderson, Giulio Vistoli, Lalage A. Katunga, Katsuhiko Funai, Luca Regazzoni, T. Blake Monroe, Ettore Gilardoni, Luca Cannizzaro, Mara Colzani, Danilo De Maddis, Giuseppe Rossoni, Renato Canevotti, Stefania Gagliardi, Marina Carini, Giancarlo Aldini
Tumor-associated myeloid cells maintain immunosuppressive microenvironments within tumors. Identification of myeloid-specific receptors to modulate tumor-associated macrophage and myeloid-derived suppressor cell (MDSC) functions remains challenging. The leukocyte immunoglobulin-like receptor B (LILRB) family members are negative regulators of myeloid cell activation. We investigated how LILRB targeting could modulate tumor-associated myeloid cell function. LILRB2 antagonism inhibited receptor-mediated activation of SHP1/2 and enhanced proinflammatory responses. LILRB2 antagonism also inhibited AKT and STAT6 activation in the presence of M-CSF and IL-4. Transcriptome analysis revealed that LILRB2 antagonism altered genes involved in cell cytoskeleton remodeling, lipid/cholesterol metabolism, and endosomal sorting pathways, as well as changed differentiation gene networks associated with inflammatory myeloid cells as opposed to their alternatively activated phenotype. LILRB2 blockade effectively suppressed granulocytic MDSC and Treg infiltration and significantly promoted in vivo antitumor effects of T cell immune checkpoint inhibitors. Furthermore, LILRB2 blockade polarized tumor-infiltrating myeloid cells from non–small cell lung carcinoma tumor tissues toward an inflammatory phenotype. Our studies suggest that LILRB2 can potentially act as a myeloid immune checkpoint by reprogramming tumor-associated myeloid cells and provoking antitumor immunity.
Hui-Ming Chen, William van der Touw, Yuan Shuo Wang, Kyeongah Kang, Sunny Mai, Jilu Zhang, Dayanira Alsina-Beauchamp, James A. Duty, Sathish Kumar Mungamuri, Bin Zhang, Thomas Moran, Richard Flavell, Stuart Aaronson, Hong-Ming Hu, Hisashi Arase, Suresh Ramanathan, Raja Flores, Ping-Ying Pan, Shu-Hsia Chen
The ubiquitin-proteasome system (UPS) degrades a protein molecule via 2 main steps: ubiquitination and proteasomal degradation. Extraproteasomal ubiquitin receptors are thought to couple the 2 steps, but this proposition has not been tested in vivo with vertebrates. More importantly, impaired UPS performance plays a major role in cardiac pathogenesis, including myocardial ischemia-reperfusion injury (IRI), but the molecular basis of UPS impairment remains poorly understood. Ubiquilin1 is a bona fide extraproteasomal ubiquitin receptor. Here, we report that mice with a cardiomyocyte-restricted knockout of Ubiquilin1 (Ubqln1-CKO mice) accumulated a surrogate UPS substrate (GFPdgn) and increased myocardial ubiquitinated proteins without altering proteasome activities, resulting in late-onset cardiomyopathy and a markedly shortened life span. When subject to regional myocardial ischemia-reperfusion, young Ubqln1-CKO mice showed substantially exacerbated cardiac malfunction and enlarged infarct size, and conversely, mice with transgenic Ubqln1 overexpression displayed attenuated IRI. Furthermore, Ubqln1 overexpression facilitated proteasomal degradation of oxidized proteins and the degradation of a UPS surrogate substrate in cultured cardiomyocytes without increasing autophagic flux. These findings demonstrate that Ubiquilin1 is essential to cardiac ubiquitination-proteasome coupling and that an inadequacy in the coupling represents a major pathogenic factor for myocardial IRI; therefore, strategies to strengthen coupling have the potential to reduce IRI.
Chengjun Hu, Yihao Tian, Hongxin Xu, Bo Pan, Erin M. Terpstra, Penglong Wu, Hongmin Wang, Faqian Li, Jinbao Liu, Xuejun Wang
Bone marrow mesenchymal stem cells (BMSCs) exhibit an age-related lineage switch between osteogenic and adipogenic fates, which contributes to bone loss and adiposity. Here we identified a long noncoding RNA, Bmncr, which regulated the fate of BMSCs during aging. Mice depleted of Bmncr (Bmncr-KO) showed decreased bone mass and increased bone marrow adiposity, whereas transgenic overexpression of Bmncr (Bmncr-Tg) alleviated bone loss and bone marrow fat accumulation. Bmncr regulated the osteogenic niche of BMSCs by maintaining extracellular matrix protein fibromodulin (FMOD) and activation of the BMP2 pathway. Bmncr affected local 3D chromatin structure and transcription of Fmod. The absence of Fmod modified the bone phenotype of Bmncr-Tg mice. Further analysis revealed that Bmncr would serve as a scaffold to facilitate the interaction of TAZ and ABL, and thus facilitate the assembly of the TAZ and RUNX2/PPARG transcriptional complex, promoting osteogenesis and inhibiting adipogenesis. Adeno-associated viral-mediated overexpression of Taz in osteoprogenitors alleviated bone loss and marrow fat accumulation in Bmncr-KO mice. Furthermore, restoring BMNCR levels in human BMSCs reversed the age-related switch between osteoblast and adipocyte differentiation. Our findings indicate that Bmncr is a key regulator of the age-related osteogenic niche alteration and cell fate switch of BMSCs.
Chang-Jun Li, Ye Xiao, Mi Yang, Tian Su, Xi Sun, Qi Guo, Yan Huang, Xiang-Hang Luo
Breast cancer (BrCa) is the malignant tumor that most seriously threatens female health; however, the molecular mechanism underlying its progression remains unclear. Here, we found that conditional deletion of hypermethylated in cancer 1 (HIC1) in the mouse mammary gland might contribute to premalignant transformation in the early stage of tumor formation. Moreover, the chemokine (C-X-C motif) ligand 14 (CXCL14) secreted by HIC1-deleted BrCa cells bound to its cognate receptor GPR85 on mammary fibroblasts in the microenvironment and was responsible for activating these fibroblasts via the ERK1/2, Akt, and neddylation pathways, whereas the activated fibroblasts promoted BrCa progression via the induction of epithelial-mesenchymal transition (EMT) by the C-C chemokine ligand 17 (CCL17)/CC chemokine receptor 4 (CCR4) axis. Finally, we confirmed that the HIC1-CXCL14-CCL17 loop was associated with the malignant progression of BrCa. Therefore, the crosstalk between HIC1-deleted BrCa cells and mammary fibroblasts might play a critical role in BrCa development. Exploring the progression of BrCa from the perspective of microenvironment will be beneficial for identifying the potential prognostic markers of breast tumor and providing more effective treatment strategies.
Yingying Wang, Xiaoling Weng, Luoyang Wang, Mingang Hao, Yue Li, Lidan Hou, Yu Liang, Tianqi Wu, Mengfei Yao, Guowen Lin, Yiwei Jiang, Guohui Fu, Zhaoyuan Hou, Xiangjun Meng, Jinsong Lu, Jianhua Wang
Angelman syndrome (AS) is a neurodevelopmental disorder in which epilepsy is common (~90%) and often refractory to antiepileptics. AS is caused by mutation of the maternal allele encoding the ubiquitin protein ligase E3A (UBE3A), but it is unclear how this genetic insult confers vulnerability to seizure development and progression (i.e., epileptogenesis). Here we implemented the flurothyl kindling and retest paradigm in AS model mice to assess epileptogenesis and to gain mechanistic insights owed to loss of maternal Ube3a. AS model mice kindled similarly to wildtype mice, but they displayed a markedly increased sensitivity to flurothyl-, kainic acid-, and hyperthermia-induced seizures measured a month later during retest. Pathological characterization revealed enhanced deposition of perineuronal nets in dentate gyrus of hippocampus of AS mice in the absence of overt neuronal loss or mossy fiber sprouting. This pro-epileptogenic phenotype resulted from Ube3a deletion in GABAergic but not glutamatergic neurons, and it was rescued by pancellular reinstatement of Ube3a at postnatal day 21 (P21), but not during adulthood. Our results suggest that epileptogenic susceptibility in AS patients is a consequence of the dysfunctional development of GABAergic circuits, which may be amenable to therapies leveraging juvenile reinstatement of UBE3A.
Bin Gu, Kelly E. Carstens, Matthew C. Judson, Katherine A. Dalton, Marie Rougié, Ellen P. Clark, Serena M. Dudek, Benjamin D. Philpot
Iron-related disorders are among the most prevalent diseases worldwide. Systemic iron homeostasis requires hepcidin, a hepatic-derived hormone that controls iron mobilization through its molecular target, ferroportin (FPN), the only known mammalian iron exporter. This pathway is perturbed in diseases that cause iron overload. Additionally, intestinal HIF-2α is essential for the local absorptive response to systemic iron deficiency and iron overload. Our data demonstrate a hetero-tissue crosstalk mechanism, where liver hepcidin regulated intestinal HIF-2α in iron deficiency, anemia, and iron overload. We show that FPN controlled cell autonomous iron efflux to regulate the activity of iron-dependent, intestinal prolyl hydroxylase domain enzymes to stabilize HIF-2α. Pharmacological blockade of HIF-2α using a clinically relevant and highly specific inhibitor successfully treated iron overload in a mouse model. These findings demonstrate a molecular link between liver hepcidin and intestinal HIF-2α that controls physiological iron uptake and drives iron hyperabsorption during iron overload.
Andrew J. Schwartz, Nupur K. Das, Sadeesh K. Ramakrishnan, Chesta Jain, Mladen Jurkovic, Jun Wu, Elizabeta Nemeth, Samira Lakhal-Littleton, Justin A. Colacino, Yatrik M. Shah
The loss of insulin-secreting β cells is characteristic among Type I and Type II diabetes. Stimulating proliferation to expand sources of β cells for transplantation remains a challenge because adult β cells do not proliferate readily. The cell cycle inhibitor p57 has been shown to control cell division in human β cells. Expression of p57 is regulated by the DNA methylation status of the Imprinting Control Region 2 (ICR2), which is commonly hypomethylated in Beckwith Wiedemann-Syndrome patients who exhibit massive β cell proliferation. We hypothesized that targeted demethylation of the ICR2 using a transcription activator-like effector protein fused to the catalytic domain of TET1 (ICR2-TET1) would repress p57 expression and promote cell proliferation. We report here that overexpression of ICR2-TET1 in human fibroblasts reduces p57 expression levels and increases proliferation. Furthermore, human islets overexpressing ICR2-TET1 exhibit repression of p57 with concomitant upregulation of Ki-67 while maintaining glucose-sensing functionality. When transplanted into diabetic, immunodeficient mice, the epigenetically edited islets show increased β cell replication compared to control islets. These findings demonstrate that epigenetic editing is a promising tool for inducing β cell proliferation, which may one day alleviate the scarcity of transplantable β cells for the treatment of diabetes.
Kristy Ou, Ming Yu, Nicholas G. Moss, Yue J. Wang, Amber W. Wang, Son C. Nguyen, Connie Jiang, Eseye Feleke, Vasumathi Kameswaran, Eric F. Joyce, Ali Naji, Benjamin Glaser, Dana Avrahami, Klaus H. Kaestner
BACKGROUND. Liquid biopsies have demonstrated that the constitutively active androgen receptor splice variant-7 (AR-V7) associates with reduced response and overall survival (OS) from endocrine therapies in castration resistant prostate cancer (CRPC). However, these studies provide little information pertaining to AR-V7 expression in prostate cancer (PC) tissue. METHODS. Following generation and validation of a novel AR-V7 antibody for immunohistochemistry, AR-V7 protein expression was determined for 358 primary prostate samples and 293 metastatic biopsies. Associations with disease progression, full length AR (AR-FL) expression, response to therapy, and gene expression was determined. RESULTS. We demonstrated that AR-V7 protein is rarely expressed (<1%) in primary PC but is frequently detected (75% of cases) following androgen deprivation therapy, with further significant (P = 0.020) increase in expression following abiraterone acetate or enzalutamide therapy. In CRPC, AR-V7 expression is predominantly (94% of cases) nuclear and correlates with AR-FL expression (P ≤ 0.001) and AR copy number (P = 0.026). However, dissociation of expression was observed suggesting mRNA splicing remains crucial for AR-V7 generation. AR-V7 expression was heterogeneous between different metastases from a patient although AR-V7 expression was similar within a metastasis. Moreover, AR-V7 expression correlated with a unique 59-gene signature in CRPC, including HOXB13, a critical co-regulator of AR-V7 function. Finally, AR-V7 negative disease associated with better PSA responses (100% vs 54%; P = 0.03) and OS (74.3 vs 25.2mo, HR 0.23 [0.07-0.79], P = 0.02) from endocrine therapies (pre-chemotherapy). CONCLUSION. This study provides impetus to develop therapies that abrogate AR-V7 signaling to improve our understanding of AR-V7 biology, and to confirm its clinical significance.
Adam Sharp, Ilsa Coleman, Wei Yuan, Cynthia Sprenger, David Dolling, Daniel Nava Rodrigues, Joshua W. Russo, Ines Figueiredo, Claudia Bertan, George Seed, Ruth Riisnaes, Takuma Uo, Antje Neeb, Jonathan Welti, Colm Morrissey, Suzanne Carreira, Jun Luo, Peter S. Nelson, Steven P. Balk, Lawrence D. True, Johann De Bono, Stephen R. Plymate
The pathogenesis of ischemic diseases remains unclear. Here we demonstrate the induction of microRNA-668 (mir-668) in ischemic acute kidney injury (AKI) in human patients, mice, and renal tubular cells. The induction was HIF-1dependant as HIF-1-deficiency in cells and kidney proximal tubules attenuated mir-668 expression. We further identified a functional HIF-1 binding site in mir-668 gene promoter. Anti-mir-668 increased apoptosis in renal tubular cells and enhanced ischemic AKI in mice, whereas mir-668 mimic was protective. Mechanistically, anti-mir-668 induced mitochondrial fragmentation, whereas mir-668 blocked mitochondrial fragmentation during hypoxia. We analyzed mir-668 target genes through immunoprecipitation of microRNA-induced silencing complexes followed by RNA deep sequencing and identified 124 protein-coding genes as likely targets of mir-668. Among these genes, only Mitochondrial Protein 18 KDa (MTP18) has been implicated in mitochondrial dynamics. In renal cells and mouse kidneys, mir-668 mimic suppressed MTP18, whereas anti-mir-668 increased MTP18 expression. Luciferase microRNA target reporter assay further verified MTP18 as a direct target of mir-668. In renal tubular cells, knockdown of MTP18 suppressed mitochondrial fragmentation and apoptosis. Together, the results suggest that mir-668 is induced via HIF-1 in ischemic AKI and, upon induction, mir-668 represses MTP18 to preserve mitochondrial dynamics for renal tubular cell survival and kidney protection.
Qingqing Wei, Haipeng Sun, Shuwei Song, Yong Liu, Pengyuan Liu, Man J. Livingston, Jianwen Wang, Mingyu Liang, Qing-Sheng Mi, Yuqing Huo, N. Stanley Nahman, Changlin Mei, Zheng Dong
In this issue of the JCI, Edelmann et al. reveal that a JAK2-V617F mutation that is common in patients with polycythemia vera and essential thrombocytosis enhances risk of developing life-threatening thromboses by increasing β1 and β2 integrin affinity for the endothelial adhesion molecules VCAM1 and ICAM2. This aberrant interaction underlies also altered myeloid trafficking to the spleen. The cover image shows the expression of endothelial VCAM1 (white) and ICAM1 (purple) together with myeloid-derived cells (yellow) and other immune cell populations in a mouse spleen. Image credit: Lars Philipsen.
JCI This Month is a digest of the research, reviews, and other features published each month.
Mitochondria transform nutrients and oxygen into chemical energy that powers a multitude of cellular functions. While mitochondrial aerobic glycolysis generates the majority of a cell’s ATP, its byproducts also have wide-ranging influences on cellular health and longevity. This review series, edited by Dr. Michael Sack, focuses on the many contributions of mitochondria to disease and aging. The reviews highlight evidence linking altered mitochondrial metabolism and oxidative stress to a range of pathophysiological phenomena: inflammation and immune dysfunction, heart failure, cancer development, metabolic disease, and more. In many diseases and conditions, mitochondrial dysfunction is considered the tipping point toward pathological progression. However, as these reviews discuss, therapeutic targeting of mitochondria may be a powerful strategy to subvert disease and aging processes.