HIV-1 latent reservoir size and diversity are stable following brief treatment interruption

• Text
• PDF

Abstract

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.

Authors

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

Melanocortin 4 receptors switch reward to aversion

• Text
• PDF

Abstract

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.

Authors

Alexandra G. DiFeliceantonio, Paul J. Kenny

TRAF4-mediated ubiquitination of NGF receptor TrkA regulates prostate cancer metastasis

• Text
• PDF

Abstract

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.

Authors

Ramesh Singh, Dileep Karri, Hong Shen, Jiangyong Shao, Subhamoy Dasgupta, Shixia Huang, Dean P. Edwards, Michael M. Ittmann, Bert W. O’Malley, Ping Yi

Endothelial cells in the innate response to allergens and initiation of atopic asthma

• Text
• PDF

Abstract

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.

Authors

Kewal Asosingh, Kelly Weiss, Kimberly Queisser, Nicholas Wanner, Mei Yin, Mark Aronica, Serpil Erzurum

Fasting-induced JMJD3 histone demethylase epigenetically activates mitochondrial fatty acid β-oxidation

• Text
• PDF

Abstract

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.

Authors

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

Motivational valence is determined by striatal melanocortin 4 receptors

• Text
• PDF

Abstract

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.

Authors

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

HIF2α in the uterine stroma permits embryo invasion and luminal epithelium detachment

• Text
• PDF

Abstract

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.

Authors

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

Altered immune cell follicular dynamics in HIV infection following influenza vaccination

• Text
• PDF

Abstract

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.

Authors

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

HECTD3 mediates TRAF3 polyubiquitination and type I interferon induction during bacterial infection

• Text
• PDF

Abstract

Lysine-63 (K63)–linked polyubiquitination of TRAF3 coordinates the engagement of pattern recognition receptors to recruited adaptor proteins and downstream activator TBK1 in pathways that induce type I interferon (IFN). Whether auto-ubiquitination or other E3 ligases mediate K63-linked TRAF3 polyubiquitination remains unclear. We demonstrated that mice deficient in E3 ligase gene Hectd3 remarkably increased host defense against infection by intracellular bacteria F. novicida, Mycobacterium, and Listeria by limiting bacterial dissemination. In the absence of HECTD3, type I IFN response was impaired during bacterial infection both in vivo and in vitro. HECTD3 regulated type I IFN production by mediating K63-linked polyubiquitination of TRAF3 at residue K138. The catalytic domain of HECTD3 regulated TRAF3 K63 polyubiquitination, which enabled TRAF3–TBK1 complex formation. Our study offers novel insights into mechanisms of TRAF3 modulation and provides potential therapeutic targets against infections by intracellular bacteria and inflammatory diseases.

Authors

Fubing Li, Yang Li, Huichun Liang, Tao Xu, Yanjie Kong, Maobo Huang, Ji Xiao, Xi Chen, Houjun Xia, Yingying Wu, Zhongmei Zhou, Xiaomin Guo, Chunmiao Hu, Chuanyu Yang, Xu Cheng, Ceshi Chen, Xiaopeng Qi

Oncogenic TRK fusions are amenable to inhibition in hematologic malignancies

• Text
• PDF

Abstract

Rearrangements involving the neurotrophic receptor kinase genes (NTRK1, NTRK2, and NTRK3; hereafter referred to as TRK) produce oncogenic fusions in a wide variety of cancers in adults and children. Although TRK fusions occur in <1% of all solid tumors, inhibition of TRK results in profound therapeutic responses resulting in breakthrough FDA-approval of the TRK inhibitor larotrectinib for adult and pediatric solid tumor patients regardless of histology. In contrast to solid tumors, the frequency of TRK fusions and clinical effects of targeting TRK in hematologic malignancies is unknown. Here, through an evaluation for TRK fusions across > 7,000 patients with hematologic malignancies, we identified TRK fusions in acute lymphoblastic leukemia (ALL), acute myeloid leukemia (AML), histiocytosis, multiple myeloma and dendritic cell neoplasms. Although TRK fusions occurred in only 0.1% of patients (8 out of 7,311 patients), they conferred responsiveness to TRK inhibition in vitro and in vivo in a patient-derived xenograft and a corresponding AML patient with ETV6-NTRK2 fusion. These data identify that despite their individual rarity, collectively TRK fusions are present in a wide variety of hematologic malignancies and predict clinically significant therapeutic responses to TRK inhibition.

Authors

Justin Taylor, Dean Pavlick, Akihide Yoshimi, Christina Marcelus, Stephen S. Chung, Jaclyn F. Hechtman, Ryma Benayed, Emiliano Cocco, Benjamin H. Durham, Lillian Bitner, Daichi Inoue, Young Rock Chung, Kerry Mullaney, Justin M. Watts, Eli L. Diamond, Lee A. Albacker, Tariq I. Mughal, Kevin Ebata, Brian B. Tuch, Nora Ku, Maurizio Scaltriti, Mikhail Roshal, Maria Arcila, Siraj Ali, David M. Hyman, Jae H. Park, Omar Abdel-Wahab

Autophagy orchestrates the regulatory program of tumor-associated myeloid-derived suppressor cells

• Text
• PDF

Abstract

Myeloid-derived suppressor cells (MDSCs) densely accumulate into tumors and potently suppress anti-tumor immune responses promoting tumor development. Targeting MDSCs in tumor immunotherapy has been hampered by lack of understanding of the molecular pathways that govern MDSC differentiation and function. Herein, we identify autophagy as a crucial pathway for MDSC-mediated suppression of anti-tumor immunity. Specifically, MDSCs in melanoma patients and mouse melanoma exhibited increased levels of functional autophagy. Ablation of autophagy in myeloid cells, significantly delayed tumor growth and endowed anti-tumor immune responses. Notably, tumor-infiltrating autophagy-deficient monocytic MDSCs (M-MDSCs) demonstrated impaired suppressive activity in vitro and in vivo, while transcriptome analysis revealed significant differences in genes related to lysosomal function. Accordingly, autophagy-deficient M-MDSCs exhibited impaired lysosomal degradation thereby enhancing surface expression of MHC class II molecules, resulting in efficient activation of tumor-specific CD4+ T cells. Finally, targeting of the membrane-associated RING-CH1 (MARCH1) E3 ubiquitin ligase, that mediates the lysosomal degradation of MHC II, in M-MDSCs, attenuated their suppressive function, and resulted in significantly decreased tumor volume followed by development of a robust anti-tumor immunity. Collectively, these findings depict autophagy as a novel molecular target of MDSC-mediated suppression of anti-tumor immunity.

Authors

Themis Alissafi, Aikaterini Hatzioannou, Konstantinos Mintzas, Roza Maria Barouni, Aggelos Banos, Sundary Sormendi, Alexandros Polyzos, Maria Xilouri, Ben Wielockx, Helen Gogas, Panayotis Verginis

Th1/Th17 polarization persists following whole-cell pertussis vaccination despite repeated acellular boosters

• Text
• PDF

Abstract

In the mid-1990s, whole-cell (wP) pertussis vaccines were associated with local and systemic adverse events, which prompted their replacement with acellular (aP) vaccines in many high-income countries. In the past decade rates of pertussis disease have increased in children receiving only acellular pertussis vaccines. We compared the immune responses to acellular pertussis boosters in children who received their initial doses with either wP or aP vaccines using activation-induced marker (AIM) assays. Specifically, we examined pertussis-specific memory CD4+ T cell responses ex vivo, highlighting a Type 2/Th2 versus Type 1/Th1 and Th17 differential polarization as a function of childhood vaccination. Remarkably, after a contemporary aP booster, cells from donors originally primed with aP were 1) associated with increased IL-4, IL-5, IL-13, IL-9 and TGF-β and decreased IFNγ and IL-17 production; 2) defective in their ex vivo capacity to expand memory cells; and 3) less capable to proliferate in vitro. These differences appeared to be T cell-specific, since equivalent increases of antibody titers and plasmablasts after aP boost were seen in both groups. In conclusion, our data suggest that long lasting effects and differential polarization and proliferation exists between adults originally vaccinated with aP versus wP despite repeated acellular boosters.

Authors

Ricardo da Silva Antunes, Mariana Babor, Chelsea Carpenter, Natalie Khalil, Mario Cortese, Alexander J Mentzer, Grégory Seumois, Christopher D. Petro, Lisa A. Purcell, Pandurangan Vijayanand, Shane Crotty, Bali Pulendran, Bjorn Peters, Alessandro Sette

Itaconic acid mediates crosstalk between macrophage metabolism and peritoneal tumors

• Text
• PDF

Abstract

Control of cellular metabolism is critical for efficient cell function, although little is known about the interplay between cell subset-specific metabolites in situ, especially in the tumor setting. Here, we determine how a macrophage-specific metabolite, itaconic acid, can regulate tumor progression in the peritoneum. We show peritoneal tumors (B16 melanoma or ID8 ovarian carcinoma) elicited a fatty acid oxidation-mediated increase in oxidative phosphorylation (OXPHOS) and glycolysis in peritoneal tissue-resident macrophages (pResMφ). Unbiased metabolomics identified itaconic acid, the product of Irg1-mediated catabolism of mitochondrial cis-aconitate, among the most highly upregulated metabolites in pResMφof tumor-bearing mice. Administration of lentivirally-encoded Irg1 shRNA significantly reduced peritoneal tumors. This resulted in reductions in OXPHOS and OXPHOS-driven production of reactive oxygen species (ROS) in pResMφ and ROS-mediated MAP kinase activation in tumor cells. Our findings demonstrate that tumors profoundly alter pResMφ metabolism, leading to the production of itaconic acid, which potentiates tumor growth. Monocytes isolated from ovarian carcinoma patient ascites fluid expressed significantly elevated levels of Irg1. Therefore, Irg1 in pResMφ represents a potential therapeutic target for peritoneal tumors.

Authors

Jonathan M. Weiss, Luke C. Davies, Megan Karwan, Lilia Ileva, Michelle K. Ozaki, Robert Y.S. Cheng, Lisa A. Ridnour, Christina M. Annunziata, David A. Wink, Daniel W. McVicar