BACKGROUND. The effect of a brief analytical treatment interruption (ATI) on the HIV-1 latent reservoir of individuals who initiate antiretroviral therapy (ART) during chronic infection is unknown. METHODS. We evaluated the impact of transient viremia on the latent reservoir in participants who underwent an ATI and at least 6 months of subsequent viral suppression in a clinical trial testing the effect of passive infusion of the broadly neutralizing Ab VRC01 during ATI. RESULTS. Measures of total HIV-1 DNA, cell-associated RNA, and infectious units per million cells (IUPM) (measured by quantitative viral outgrowth assay [QVOA]) were not statistically different before or after ATI. Phylogenetic analyses of HIV-1 env sequences from QVOA and proviral DNA demonstrated little change in the composition of the virus populations comprising the pre- and post-ATI reservoir. Expanded clones were common in both QVOA and proviral DNA sequences. The frequency of clonal populations differed significantly between QVOA viruses, proviral DNA sequences, and the viruses that reactivated in vivo. CONCLUSIONS. The results indicate that transient viremia from ATI does not substantially alter measures of the latent reservoir, that clonal expansion is prevalent within the latent reservoir, and that characterization of latent viruses that can reactivate in vivo remains challenging. TRIAL REGISTRATION. ClinicalTrials.gov NCT02463227 FUNDING. Funding was provided by the NIH.
D. Brenda Salantes, Yu Zheng, Felicity Mampe, Tuhina Srivastava, Subul Beg, Jun Lai, Jonathan Z. Li, Randall L. Tressler, Richard A. Koup, James Hoxie, Mohamed Abdel-Mohsen, Scott Sherrill-Mix, Kevin McCormick, E. Turner Overton, Frederic D. Bushman, Gerald H. Learn, Robert F. Siliciano, Janet M. Siliciano, Pablo Tebas, Katharine J. Bar
The ability to recognize and avoid noxious stimuli is essential for survival. The factors that determine whether a given stimulus is considered positive or negative are complex and not fully understood. In this issue of the JCI, Klawonn and colleagues demonstrate that melanocortin 4 receptor (MC4R) signaling is critical for proper responses to negative stimuli. Mice lacking MC4R were shown to have a surprising preference for aversive stimuli compared with WT animals. Moreover, the authors provide evidence that avoidance behaviors are mediated by hypothalamic POMC neurons signaling to striatal dopamine D1 receptor–expressing medium spiny neurons. Together, these results provide important insight into the regulation of responses to aversive stimuli.
Alexandra G. DiFeliceantonio, Paul J. Kenny
Receptor tyrosine kinases (RTKs) are important drivers of cancers. In addition to genomic alterations, aberrant activation of WT RTKs plays an important role in driving cancer progression. However, the mechanisms underlying how RTKs drive prostate cancer remain incompletely characterized. Here we show that non-proteolytic ubiquitination of RTK regulates its kinase activity and contributes to RTK-mediated prostate cancer metastasis. TRAF4, an E3 ubiquitin ligase, is highly expressed in metastatic prostate cancer. We demonstrated here that it is a key player in regulating RTK-mediated prostate cancer metastasis. We further identified TrkA, a neurotrophin RTK, as a TRAF4-targeted ubiquitination substrate that promotes cancer cell invasion and found that inhibition of TrkA activity abolished TRAF4-dependent cell invasion. TRAF4 promoted K27- and K29-linked ubiquitination at the TrkA kinase domain and increased its kinase activity. Mutation of TRAF4-targeted ubiquitination sites abolished TrkA tyrosine autophosphorylation and its interaction with downstream proteins. TRAF4 knockdown also suppressed nerve growth factor (NGF) stimulated TrkA downstream p38 MAPK activation and invasion-associated gene expression. Furthermore, elevated TRAF4 levels significantly correlated with increased NGF-stimulated invasion–associated gene expression in prostate cancer patients, indicating that this signaling axis is significantly activated during oncogenesis. Our results revealed a posttranslational modification mechanism contributing to aberrant non-mutated RTK activation in cancer cells.
Ramesh Singh, Dileep Karri, Hong Shen, Jiangyong Shao, Subhamoy Dasgupta, Shixia Huang, Dean P. Edwards, Michael M. Ittmann, Bert W. O’Malley, Ping Yi
Protease-activated receptor 2 (PAR-2), an airway epithelial pattern recognition receptor (PRR), participates in the genesis of house dust mite–induced (HDM-induced) asthma. Here, we hypothesized that lung endothelial cells and proangiogenic hematopoietic progenitor cells (PACs) that express high levels of PAR-2 contribute to the initiation of atopic asthma. HDM extract (HDME) protease allergens were found deep in the airway mucosa and breaching the endothelial barrier. Lung endothelial cells and PACs released the Th2-promoting cytokines IL-1α and GM-CSF in response to HDME, and the endothelium had PAC-derived VEGF-C–dependent blood vessel sprouting. Blockade of the angiogenic response by inhibition of VEGF-C signaling lessened the development of inflammation and airway remodeling in the HDM model. Reconstitution of the bone marrow in WT mice with PAR-2–deficient bone marrow also reduced airway inflammation and remodeling. Adoptive transfer of PACs that had been exposed to HDME induced angiogenesis and Th2 inflammation with remodeling similar to that induced by allergen challenge. Our findings identify that lung endothelium and PACs in the airway sense allergen and elicit an angiogenic response that is central to the innate nonimmune origins of Th2 inflammation.
Kewal Asosingh, Kelly Weiss, Kimberly Queisser, Nicholas Wanner, Mei Yin, Mark Aronica, Serpil Erzurum
Jumonji D3 (JMJD3) histone demethylase epigenetically regulates development and differentiation, immunity, and tumorigenesis by demethylating a gene repression histone mark, H3K27-me3, but a role for JMJD3 in metabolic regulation has not been described. SIRT1 deacetylase maintains energy balance during fasting by directly activating both hepatic gluconeogenic and mitochondrial fatty acid β-oxidation genes, but the underlying epigenetic and gene-specific mechanisms remain unclear. In this study, JMJD3 was identified unexpectedly as a gene-specific transcriptional partner of SIRT1 and epigenetically activated mitochondrial β-oxidation, but not gluconeogenic, genes during fasting. Mechanistically, JMJD3, together with SIRT1 and the nuclear receptor PPARα, formed a positive autoregulatory loop upon fasting-activated PKA signaling and epigenetically activated β-oxidation–promoting genes, including Fgf21, Cpt1a, and Mcad. Liver-specific downregulation of JMJD3 resulted in intrinsic defects in β-oxidation, which contributed to hepatosteatosis as well as glucose and insulin intolerance. Remarkably, the lipid-lowering effects by JMJD3 or SIRT1 in diet-induced obese mice were mutually interdependent. JMJD3 histone demethylase may serve as an epigenetic drug target for obesity, hepatosteatosis, and type 2 diabetes that allows selective lowering of lipid levels without increasing glucose levels.
Sunmi Seok, Young-Chae Kim, Sangwon Byun, Sunge Choi, Zhen Xiao, Naoki Iwamori, Yang Zhang, Chaochen Wang, Jian Ma, Kai Ge, Byron Kemper, Jongsook Kim Kemper
It is critical for survival to assign positive or negative valence to salient stimuli in a correct manner. Accordingly, harmful stimuli and internal states characterized by perturbed homeostasis are accompanied by discomfort, unease, and aversion. Aversive signaling causes extensive suffering during chronic diseases, including inflammatory conditions, cancer, and depression. Here, we investigated the role of melanocortin 4 receptors (MC4Rs) in aversive processing using genetically modified mice and a behavioral test in which mice avoid an environment that they have learned to associate with aversive stimuli. In normal mice, robust aversions were induced by systemic inflammation, nausea, pain, and κ opioid receptor–induced dysphoria. In sharp contrast, mice lacking MC4Rs displayed preference or indifference toward the aversive stimuli. The unusual flip from aversion to reward in mice lacking MC4Rs was dopamine dependent and associated with a change from decreased to increased activity of the dopamine system. The responses to aversive stimuli were normalized when MC4Rs were reexpressed on dopamine D1 receptor–expressing cells or in the striatum of mice otherwise lacking MC4Rs. Furthermore, activation of arcuate nucleus proopiomelanocortin neurons projecting to the ventral striatum increased the activity of striatal neurons in an MC4R-dependent manner and elicited aversion. Our findings demonstrate that melanocortin signaling through striatal MC4Rs is critical for assigning negative motivational valence to harmful stimuli.
Anna Mathia Klawonn, Michael Fritz, Anna Nilsson, Jordi Bonaventura, Kiseko Shionoya, Elahe Mirrasekhian, Urban Karlsson, Maarit Jaarola, Björn Granseth, Anders Blomqvist, Michael Michaelides, David Engblom
Although it has been reported that hypoxia inducible factor 2 α (Hif2a), a major transcriptional factor inducible by low oxygen tension, is expressed in the mouse uterus during embryo implantation, its role in pregnancy outcomes remains unclear. This study aimed to clarify functions of uterine HIF using transgenic mouse models. Mice with deletion of Hif2a in the whole uterus (Hif2a-uKO mice) showed infertility due to implantation failure. Supplementation with progesterone (P4) and leukemia inhibitory factor (LIF) restored decidual growth arrest and aberrant position of implantation sites in Hif2a-uKO mice, respectively, but did not rescue pregnancy failure. Histological analyses in Hif2a-uKO mice revealed persistence of the intact luminal epithelium, which blocked direct contact between stroma and embryo, inactivation of PI3K-AKT pathway (embryonic survival signal), and failed embryo invasion. Mice with stromal deletion of Hif2a (Hif2a-sKO mice) showed infertility with impaired embryo invasion and those with epithelial deletion of Hif2a (Hif2a-eKO mice) showed normal fertility, suggesting the importance of stromal HIF2α in embryo invasion. This was reflected in reduced expression of membrane type 2 metalloproteinase (MT2-MMP), lysyl oxidase (LOX), VEGF, and adrenomedullin (ADM) in Hif2a-uKO stroma at the attachment site, suggesting that stromal HIF2α regulates these mediators to support blastocyst invasion. These findings provide new insight that stromal HIF2α allows trophoblast invasion through detachment of the luminal epithelium and activation of an embryonic survival signal.
Leona Matsumoto, Yasushi Hirota, Tomoko Saito-Fujita, Norihiko Takeda, Tomoki Tanaka, Takehiro Hiraoka, Shun Akaeda, Hidetoshi Fujita, Ryoko Shimizu-Hirota, Shota Igaue, Mitsunori Matsuo, Hirofumi Haraguchi, Mayuko Saito-Kanatani, Tomoyuki Fujii, Yutaka Osuga
HIV infection changes the lymph node (LN) tissue architecture, potentially impairing the immunologic response to antigenic challenge. The tissue-resident immune cell dynamics in virologically suppressed HIV+ patients on combination antiretroviral therapy (cART) are not clear. We obtained LN biopsies before and 10 to 14 days after trivalent seasonal influenza immunization from healthy controls (HCs) and HIV+ volunteers on cART to investigate CD4+ T follicular helper (Tfh) and B cell dynamics by flow cytometry and quantitative imaging analysis. Prior to vaccination, compared with those in HCs, HIV+ LNs exhibited an altered follicular architecture, but harbored higher numbers of Tfh cells and increased IgG+ follicular memory B cells. Moreover, Tfh cell numbers were dependent upon preservation of the follicular dendritic cell (FDC) network and were predictive of the magnitude of the vaccine-induced IgG responses. Interestingly, postvaccination LN samples in HIV+ participants had significantly (P = 0.0179) reduced Tfh cell numbers compared with prevaccination samples, without evidence for peripheral Tfh (pTfh) cell reduction. We conclude that influenza vaccination alters the cellularity of draining LNs of HIV+ persons in conjunction with development of antigen-specific humoral responses. The underlying mechanism of Tfh cell decline warrants further investigation, as it could bear implications for the rational design of HIV vaccines.
Eirini Moysi, Suresh Pallikkuth, Leslie R. De Armas, Louis E. Gonzalez, David Ambrozak, Varghese George, David Huddleston, Rajendra Pahwa, Richard A. Koup, Constantinos Petrovas, Savita Pahwa
EZH2-mediated epigenetic regulation of T cell differentiation and regulatory T cell function has been described previously; however, the role of EZH2 in T cell–mediated anti-tumor immunity, especially in the context of immune checkpoint therapy, is not understood. Here, we showed that genetic depletion of EZH2 in regulatory T cells (FoxP3creEZH2fl/fl mice) leads to robust anti-tumor immunity. In addition, pharmacological inhibition of EZH2 in human T cells using CPI-1205 elicited phenotypic and functional alterations of the regulatory T cells and enhanced cytotoxic activity of effector T cells. We observed that ipilimumab (anti–CTLA-4) increased EZH2 expression in peripheral T cells from treated patients. We hypothesized that inhibition of EZH2 expression in T cells would increase the effectiveness of anti–CTLA-4 therapy, which we tested in murine models. Collectively, our data demonstrated that modulating EZH2 expression in T cells can improve anti-tumor responses elicited by anti–CTLA-4 therapy, which provides a strong rationale for a combination trial of CPI-1205 plus ipilimumab.
Sangeeta Goswami, Irina Apostolou, Jan Zhang, Jill Skepner, Swetha Anandhan, Xuejun Zhang, Liangwen Xiong, Patrick Trojer, Ana Aparicio, Sumit K. Subudhi, James P. Allison, Hao Zhao, Padmanee Sharma
Painful signals are transmitted by mutisynaptic glutamatergic pathways. Their first synapse between primary nociceptors and excitatory spinal interneurons gates sensory load. Glutamate release herein is orchestrated by Ca2+ sensor proteins with neuronal calcium-binding protein 2 (NECAB2) being particularly abundant. However, neither the importance of NECAB2+ neuronal contingents in dorsal root ganglia (DRG) and spinal cord nor function-determination by NECAB2 has been defined. A combination of histochemistry and single-cell RNA-seq showed NECAB2 in small/medium-sized C- and Aδ D-hair low threshold mechanoreceptors in DRG, as well as in protein kinase γ-positive excitatory spinal interneurons. NECAB2 was downregulated by peripheral nerve injury, offering the hypothesis that NECAB2 loss-of-funtion could limit pain sensation. Indeed, Necab2–/– mice reached a pain-free state significantly faster after peripheral inflammation than wild-type littermates. Genetic access to transiently-activated neurons revealed that a mediodorsal cohort of NECAB2+ neurons mediates inflammatory pain in mouse spinal dorsal horn. Here, besides dampening excitatory transmission in spinal interneurons, NECAB2 limited pronociceptive brain-derived neurotrophic factor release from sensory afferents. Hox8b-dependent reinstatement of NECAB2 expression in Necab2–/– mice then demonstrated that spinal/DRG NECAB2 alone could control inflammation-induced sensory hyperensitivity. Overall, we identify NECAB2 as a critical component of pro-nociceptive pain signaling whose inactivation offers substantial pain relief.
Ming-Dong Zhang, Jie Su, Csaba Adori, Valentina Cinquina, Katarzyna Malenczyk, Fatima Girach, Changgeng Peng, Patrik Ernfors, Peter Löw, Lotta Borgius, Ole Kiehn, Masahiko Watanabe, Mathias Uhlén, Nicholas Mitsios, Jan Mulder, Tibor Harkany, Tomas Hökfelt
T cells must migrate in order to encounter antigen-presenting cells (APCs) and to execute their varied functions in immune defense and inflammation. ATP release and autocrine signaling through purinergic receptors contribute to T cell activation at the immune synapse that T cells form with APCs. Here, we show that T cells also require ATP release and purinergic signaling for their migration to APCs. We found that the chemokine SDF-1α triggered mitochondrial ATP production, rapid bursts of ATP release, and increased migration of primary human CD4+ T cells. This process depended on pannexin-1 ATP release channels and autocrine stimulation of P2X4 receptors. SDF-1α stimulation caused localized accumulation of mitochondria with P2X4 receptors near the front of cells, resulting in a feed-forward signaling mechanism that promotes cellular Ca2+ influx and sustains mitochondrial ATP synthesis at levels needed for pseudopod protrusion, T cell polarization, and cell migration. Inhibition of P2X4 receptors blocked the activation and migration of T cells in vitro. In a mouse lung transplant model, P2X4 receptor antagonist treatment prevented the recruitment of T cells into allograft tissue and the rejection of lung transplants. Our findings suggest that P2X4 receptors are therapeutic targets for immunomodulation in transplantation and inflammatory diseases.
Carola Ledderose, Kaifeng Liu, Yutaka Kondo, Christian J. Slubowski, Thomas Dertnig, Sara Denicoló, Mona Arbab, Johannes Hubner, Kirstin Konrad, Mahtab Fakhari, James A. Lederer, Simon C. Robson, Gary A. Visner, Wolfgang G. Junger
Acute pancreatitis (AP), a human disease in which the pancreas digests itself, has substantial mortality with no specific therapy. The major causes of AP are alcohol abuse and gallstone complications, but it also occurs as an important side effect of the standard Asparaginase-based therapy for childhood acute lymphoblastic leukaemia. Previous investigations into the mechanisms underlying pancreatic acinar cell death induced by alcohol metabolites, bile acids or Asparaginase indicated that loss of intracellular ATP generation is a significant factor. In isolated mouse pancreatic acinar cells or cell clusters, we now report that removal of extracellular glucose had little effect on this ATP loss, suggesting that glucose metabolism was severely inhibited under these conditions. Surprisingly, we show that replacing glucose with galactose prevented or markedly reduced the loss of ATP and any subsequent necrosis. Addition of pyruvate had a similar protective effect. We also studied the effect of galactose in vivo in mouse models of AP induced either by a combination of fatty acids and ethanol or Asparaginase. In both cases, galactose markedly reduced acinar necrosis and inflammation. Based on these data we suggest that galactose feeding may be used to protect against AP.
Shuang Peng, Julia V. Gerasimenko, Tetyana M. Tsugorka, Oleksiy Gryshchenko, Sujith Samarasinghe, Ole H. Petersen, Oleg V. Gerasimenko
PRDM16 is a transcriptional co-regulator involved in translocations in acute myeloblastic leukemia (AML), myelodysplastic syndromes and T acute lymphoblastic leukemia that is highly expressed in and required for the maintenance of hematopoietic stem cells (HSCs), and can be aberrantly expressed in AML. Prdm16 is expressed as full-length (fPrdm16) and short (sPrdm16) isoforms, the latter lacking the N-terminal PR-domain. The role of both isoforms in normal and malignant hematopoiesis is unclear. We show here that fPrdm16 was critical for HSC maintenance, induced multiple genes involved in GTPase signaling and repressed inflammation, while sPrdm16 supported B-cell development biased towards marginal zone B-cells and induced an inflammatory signature. In a mouse model of human MLL-AF9 leukemia fPrdm16 extended latency, while sPrdm16 shortened latency and induced a strong inflammatory signature, including several cytokines and chemokines that are associated with myelodysplasia and with a worse prognosis in human AML. Finally, in human NPM1-mutant and in MLL-translocated AML high expression of PRDM16, which negatively impacts outcome, was associated with inflammatory gene expression, thus corroborating the mouse data. Our observations demonstrate distinct roles for Prdm16 isoforms in normal HSCs and AML, and identify sPrdm16 as one of the drivers of prognostically adverse inflammation in leukemia.
David J. Corrigan, Larry L. Luchsinger, Mariana Justino de Almeida, Linda J. Williams, Alexandros Strikoudis, Hans-Willem Snoeck
In this issue, Bao et al. investigated the evolution of breast cancer spread to lymph nodes by sequencing laser-captured single cells from morphologically distinct areas of primary breast tumors and metastases, revealing that metastatic capability correlated with copy number variations in specific genomic regions. The cover image visualizes the sequencing of single cells, a technique enabling analyses of clonal evolution that account for cell type, spatial location, and within-tumor genetic variation. Image credit: Henrik Ditzel and Li Bao.
JCI This Month is a digest of the research, reviews, and other features published each month.
Cellular senescence is a normal consequence of aging, resulting from lifelong accumulation of DNA damage that triggers an end to cell replication. Although senescent cells no longer divide, they persist in their tissue of origin and develop characteristics that can hasten and exacerbate age-related disease. This series addresses the contribution of cellular senescence to cardiovascular, neurodegenerative, and arthritic disorders as well as the senescent phenotypes in various tissues and cell types. In addition to their cell-intrinsic effects, senescent cells develop the ability to negatively influence healthy neighboring cells and immune cells by secreting senescence-associated set of cytokines and mediators known as the SASP. These reviews also highlight ongoing efforts to accurately identify, target, and eliminate senescent cells or otherwise combat their deleterious effects in disease. One day, this work may provide the basis for therapies targeting aging cells in multiple organs.