Internal Medicine Commons^™

Development, Expansion And Role Of Myeloid-Derived Suppressor Cells In Post-Sepsis Immune Suppression, Tuqa Alkhateeb

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Myeloid-derived suppressor cells (MDSCs) numbers increase significantly in sepsis and are associated with high mortality rates. These myeloid cell precursors promote immunosuppression, especially in the late (post sepsis) stage. However, the mechanisms that underlie MDSC expansion and programming are not completely understood. To investigate these mechanisms, we used a cecal-ligation and puncture (CLP) mouse model of polymicrobial sepsis that progresses from an early/acute proinflammatory phase to a late/chronic immunosuppressive phase. Previous studies in our laboratory showed that microRNA (miR)-21 and miR-181b elevate levels of the transcription factor nuclear factor 1 (NFI-A) that promotes MDSC expansion. We report here that miR-21 …

Topological Dna Damage, Telomere Attrition And T Cell Senescence During Chronic Viral Infections, Yingjie Ji, Xindi Dang, Lam Ngoc Thao Nguyen, Lam Nhat Nguyen, Jaun Zhao, Dechao Cao, Sushant Khanal, Madison Schank, Xiao Y. Wu, Zheng D. Morrison, Yue Zou, Mohamed El Gazzar, Shunbin Ning, Ling Wang, Jonathan P. Moorman, Zhi Q. Yao

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Background: T cells play a key role in controlling viral infections; however, the underlying mechanisms regulating their functions during human viral infections remain incompletely understood. Here, we used CD4 T cells derived from individuals with chronic viral infections or healthy T cells treated with camptothecin (CPT) - a topoisomerase I (Top 1) inhibitor - as a model to investigate the role of DNA topology in reprogramming telomeric DNA damage responses (DDR) and remodeling T cell functions.

Results: We demonstrated that Top 1 protein expression and enzyme activity were significantly inhibited, while the Top 1 cleavage complex (TOP1cc) was …

Disruption Of Telomere Integrity And Dna Repair Machineries By Kml001 Induces T Cell Senescence, Apoptosis, And Cellular Dysfunctions, Dechao Cao, Juan Zhao, Lan N. Nguyen, Lam N. T. Nguyen, Sushant Khanal, Xindi Dang, Madison Schank, Bal K. Chand Thakuri, Xiao Y. Wu, Zheng D. Morrison, Mohamed El Gazzar, Yue Zou, Shunbin Ning, Ling Wang, Jonathan P. Moorman, Zhi Q. Yao

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T cells in chronic viral infections are featured by premature aging with accelerated telomere erosion, but the mechanisms underlying telomere attrition remain unclear. Here, we employed human CD4 T cells treated with KML001 (a telomere-targeting drug) as a model to investigate the role of telomere integrity in remodeling T cell senescence. We demonstrated that KML001 could inhibit cell proliferation, cytokine production, and promote apoptosis via disrupting telomere integrity and DNA repair machineries. Specifically, KML001-treated T cells increased dysfunctional telomere-induced foci (TIF), DNA damage marker γH2AX, and topoisomerase cleavage complex (TOPcc) accumulation, leading to telomere attrition. Mechanistically, KML001 compromised telomere integrity …

P62-Mediated Selective Autophagy Endows Virus-Transformed Cells With Insusceptibility To Dna Damage Under Oxidative Stress, Ling Wang, Mary E. A. Howell, Aryianna Sparks Wallace, Caroline Hawkins, Camri A. Nicksic, Carissa Kohne, Kenton H. Hall, Jonathan P. Moorman, Zhi Q. Yao, Shunbin Ning

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DNA damage response (DDR) and selective autophagy both can be activated by reactive oxygen/nitrogen species (ROS/RNS), and both are of paramount importance in cancer development. The selective autophagy receptor and ubiquitin (Ub) sensor p62 plays a key role in their crosstalk. ROS production has been well documented in latent infection of oncogenic viruses including Epstein-Barr Virus (EBV). However, p62-mediated selective autophagy and its interplay with DDR have not been investigated in these settings. In this study, we provide evidence that considerable levels of p62-mediated selective autophagy are spontaneously induced, and correlate with ROS-Keap1-NRF2 pathway activity, in virus-transformed cells. Inhibition of …

Hcv-Associated Exosomes Promote Myeloid-Derived Suppressor Cell Expansion Via Inhibiting Mir-124 To Regulate T Follicular Cell Differentiation And Function, Ling Wang, Dechao Cao, Ling Wang, Juan Zhao, Lam Nhat Nguyen, Xindi Dang, Yingjie Ji, Xiao Y. Wu, Zheng D. Morrison, Qian Xie, Mohamed El Gazzar, Shunbin Ning, Jonathon P. Moorman, Zhi Q. Yao

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Virus-infected cells can regulate non-permissive bystander cells, but the precise mechanisms remain incompletely understood. Here we report that this process can be mediated by transfer of viral RNA-loaded exosomes shed from infected cells to myeloid-derived suppressor cells (MDSCs), which in turn regulate the differentiation and function of T cells during viral infection. Specifically, we demonstrated that patients with chronic hepatitis C virus (HCV) infection exhibited significant increases in T follicular regulatory (TFR) cells and decreases in T follicular helper (TFH) cells. These MDSC-mediated T-cell dysregulations resulted in an increased ratio of TFR/TFH and IL-10 production in peripheral blood. Specifically, co-culture …

Inhibition Of Trf2 Accelerates Telomere Attrition And Dna Damage In Naïve Cd4 T Cells During Hcv Infection, Lam Nhat Nguyen, Juan Zhao, Dechao Cao, Xindi Dang, Ling Wang, Jianqi Lian, Ying Zhang, Zhansheng Jia, Xiao Y. Wu, Zheng Morrison, Qian Xie, Yingjie Ji, Zheng Zhang, Mohammed El Gazzar, Shunbin Ning, Jonathan P. Moorman, Zhi Q. Yao

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T cells play a crucial role in viral clearance and vaccine responses; however, the mechanisms that regulate their homeostasis during viral infections remain unclear. In this study, we investigated the machineries of T-cell homeostasis and telomeric DNA damage using a human model of hepatitis C virus (HCV) infection. We found that naïve CD4 T cells in chronically HCV-infected patients (HCV T cells) were significantly reduced due to apoptosis compared with age-matched healthy subjects (HSs). These HCV T cells were not only senescent, as demonstrated by overexpression of aging markers and particularly shortened telomeres; but also DNA damaged, as evidenced by …

Insufficiency Of Dna Repair Enzyme Atm Promotes Naive Cd4 T-Cell Loss In Chronic Hepatitis C Virus Infection, Juan Zhao, Xindi Dang, Peixin Zhang, Lam Nhat Nguyen, Dechao Cao, Lin Wang, Xiaoyuan Wu, Zheng D. Morrison, Ying Zhang, Zhansheng Jia, Qian Xie, Ling Wang, Shunbin Ning, Mohamed El Gazzar, Jonathan P. Moorman, Zhi Q. Yao

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T cells have a crucial role in viral clearance and vaccine response; however, the mechanisms regulating their responses to viral infections or vaccinations remain elusive. In this study, we investigated T-cell homeostasis, apoptosis, DNA damage, and repair machineries in a large cohort of subjects with hepatitis C virus (HCV) infection. We found that naive CD4 T cells in chronically HCV-infected individuals (HCV T cells) were significantly reduced compared with age-matched healthy subjects. In addition, HCV T cells were prone to apoptosis and DNA damage, as evidenced by increased 8-oxoguanine expression and γH2AX/53BP1-formed DNA damage foci—hallmarks of DNA damage responses. Mechanistically, …

Limd1 Is Induced By And Required For Lmp1 Signaling, And Protects Ebv-Transformed Cells From Dna Damage-Induced Cell Death, Ling Wang, Mary E. A. Howell, Brooke Mcpeak, Katrina Riggs, Carissa Kohne, Jether Uel Yohanon, Daniel E. Foxler, Tyson V. Sharp, Jonathon P. Moorman, Zhi Q. Yao, Shunbin Ning

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LIMD1 (LIM domain-containing protein 1) is considered as a tumor suppressor, being deregulated in many cancers to include hematological malignancies; however, very little is known about the underlying mechanisms of its deregulation and its roles in carcinogenesis. Epstein-Barr Virus (EBV) is associated with a panel of malignancies of lymphocytic and epithelial origin. Using high throughput expression profiling, we have previously identified LIMD1 as a common marker associated with the oncogenic transcription factor IRF4 in EBV-related lymphomas and other hematological malignancies. In this study, we have identified potential conserved IRF4- and NFκB-binding motifs in the LIMD1 gene promoter, and both are …

Lmp1 Signaling Pathway Activates Irf4 In Latent Ebv Infection And A Positive Circuit Between Pi3k And Src Is Required, Ling Wang, Junping Ren, Guang Li, Jonathan P. Moorman, Zhi Q. Yao, Shunbin Ning

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Interferon (IFN) regulatory factors (IRFs) have crucial roles in immune regulation and oncogenesis. We have recently shown that IRF4 is activated through c-Src-mediated tyrosine phosphorylation in virus-transformed cells. However, the intracellular signaling pathway triggering Src activation of IRF4 remains unknown. In this study, we provide evidence that Epstein–Barr virus (EBV) latent membrane protein 1 (LMP1) promotes IRF4 phosphorylation and markedly stimulates IRF4 transcriptional activity, and that Src mediates LMP1 activation of IRF4. As to more precise mechanism, we show that LMP1 physically interacts with c-Src, and the phosphatidylinositol 3 kinase (PI3K) subunit P85 mediates their interaction. Depletion of P85 by …

"Toll-Free" Pathways For Production Of Type I Interferons, Ling Wang, Shunbin Ning

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Pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs) are recognized by different cellular pathogen recognition receptors (PRRs), which are expressed on cell membrane or in the cytoplasm of cells of the innate immune system. Nucleic acids derived from pathogens or from certain cellular conditions represent a large category of PAMPs/DAMPs that trigger production of type I interferons (IFN-I) in addition to pro-inflammatory cytokines, by specifically binding to intracellular Toll-like receptors or cytosolic receptors. These cytosolic receptors, which are not related to TLRs and we call them "Toll-free" receptors, include the RNA-sensing RIG-I like receptors (RLRs), the DNA-sensing HIN200 family, …

Identification Of Kansarl As The First Cancer Predisposition Fusion Gene Specific To The Population Of European Ancestry Origin, Jeff Xiwu Zhou, Xiaoyan Yang, Shunbin Ning, Ling Wang, Kesheng Wang, Yanbin Zhang, Fenghua Yuan, Fengli Li, David D. Zhuo, Liren Tang, Degen Zhuo

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Gene fusion is one of the hallmarks of cancer. Recent advances in RNA-seq of cancer transcriptomes have facilitated the discovery of fusion transcripts. In this study, we report identification of a surprisingly large number of fusion transcripts, including six KANSARL (KANSL1-ARL17A) transcripts that resulted from the fusion between the KANSL1 and ARL17A genes using a RNA splicingcode model. Five of these six KANSARL fusion transcripts are novel. By systematic analysis of RNA-seq data of glioblastoma, prostate cancer, lung cancer, breast cancer, and lymphoma from different regions of the World, we have found that KANSARL fusion transcripts were rarely detected in …

Identification Of Pp1 As The First Phosphatase For Irf7, Shunbin Ning, Ling Wang

ETSU Faculty Works

Excerpt: Interferon (IFN) regulatory factor 7 (IRF7) is phosphorylated and activated in response to pathogenic infections for production of type I IFNs

Viral And Cellular Micrornas In Regulation Of Ebv Latency And Oncogenesis, Ling Wang, Shunbin Ning

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Epstein-Barr virus (EBV), an oncogenic virus that ubiquitously establishes life-long persistence in humans, encodes viral miRNAs in two clusters, BHRF1 and BART. EBV also regulates expression of a large pool of cellular miRNAs, including miR-155, miR-146a, miR-21, miR-29, and miR-34a. These miRNAs targets both viral and cellular genes involved in the entire viral lifetime from lytic infection to oncogenesis, including viral replication, immune responses, cell cycle regulation, apoptosis, and cell proliferation, and are indispensable for persistent infection, latency establishment and maintenance, and cancer development. Among them, circulating miRNAs and unique miRNA profiles are promising diagnosis and prognosis biomarkers alone or …

Inactivation Of Type I Ifn Jak-Stat Pathway In Ebv Latency, Shunbin Ning, Ling Wang

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Epstein-Barr Virus (EBV) latent infection is associated with a variety of lymphomas and carcinomas. Interferon (IFN) Regulatory Factors (IRFs) are a family of transcription factors, among which IRF7 is the “master” regulator of type I IFNs (IFN-I) that defends against invading viruses. Robust IFN-I responses require a positive feedback loop between IRF7 and IFN-I. In recent years, we have discovered that IRF7 is significantly induced and activated by the principal EBV oncoprotein--Latent Membrane Protein 1 (LMP1); however, IRF7 fails to trigger robust IFN-I responses in EBV latency. We believe this intriguing finding is critical for EBV latency and oncogenesis, yet …

Expansion Of Myeloid-Derived Suppressor Cells Promotes Differentiation Of Regulatory T Cells In Hiv-1+ Individuals, Ling Wang, Juan Zhao, Junping P. Ren, Xiao Y. Wu, Zheng D. Morrison, Mohamed A. El Gazzar, Shunbin Ning, Jonathan P. Moorman, Zhi Q. Yao

ETSU Faculty Works

Objective: Regulatory T cells (Tregs) contribute to HIV-1 disease progression by impairing antiviral immunity; however, the precise mechanisms responsible for the development of Tregs in the setting of HIV-1 infection are incompletely understood.

Design: In this study, we provide evidence that HIV-induced expansion of monocytic myeloid-derived suppressor cells (M-MDSCs) promote the differentiation of Foxp3+ Tregs.

Methods: We measured MDSC induction and cytokine expression by flow cytometry and analyzed their functions by coculturing experiments.

Results: We observed a dramatic increase in M-MDSC frequencies in the peripheral blood of HIV-1 seropositive (HIV-1+) individuals, even in those on antiretroviral therapy with undetectable viremia, …

Protein Phosphatase 1 Abrogates Irf7-Mediated Type I Ifn Response In Antiviral Immunity, Ling Wang, Juan Zhao, Junping Ren, Kenton H. Hall, Jonathan P. Moorman, Zhi Q. Yao, Shunbin Ning

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Interferon (IFN) regulatory factor 7 (IRF7) plays a key role in the production of IFN‐α in response to viral infection, and phosphorylation at IRF7 C‐terminal serine sites is prelude to its function. However, phosphatases that negatively regulate IRF7 phosphorylation and activity have not been reported. In this study, we have identified a conserved protein phosphatase 1 (PP1)‐binding motif in human and mouse IRF7 proteins, and shown that PP1 physically interacts with IRF7. Exogenous expression of PP1 subunits (PP1α, β, or γ) ablates IKKε‐stimulated IRF7 phosphorylation and dramatically attenuates IRF7 transcriptional activity. Inhibition of PP1 activity significantly increases IRF7 phosphorylation and …

Hcv-Induced Mir146a Controls Socs1/Stat3 And Cytokine Expression In Monocytes To Promote Regulatory T-Cell Development, Junping Ren, Rue S. Ying, Yong Q. Cheng, Ling Wang, Mohamed A. El Gazzar, Guang Y. Li, Shun B. Ning, Jonathon P. Moorman, Zhi Q. Yao

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Host innate and adaptive immune responses must be tightly regulated by an intricate balance between positive and negative signals to ensure their appropriate onset and termination while fighting pathogens and avoiding autoimmunity; persistent pathogens may usurp these regulatory machineries to dampen host immune responses for their persistence in vivo. Here, we demonstrate that miR146a is up‐regulated in monocytes from hepatitis C virus (HCV )‐infected individuals compared to control subjects. Interestingly, miR146a expression in monocytes without HCV infection increased, whereas its level in monocytes with HCV infection decreased, following Toll‐like receptor (TLR ) stimulation. This miR146a induction by HCV infection …

Human Dna Exonuclease Trex1 Is Also An Exoribonuclease That Acts On Single-Stranded Rna, Fenghua Yuan, Tanmay Dutta, Ling Wang, Lei Song, Liya Gu, Liangyue Qian, Anaid Benitez, Shunbin Ning, Arun Malhotra, Murray P. Deutcher, Yanbin Zhang

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3′ repair exonuclease 1 (TREX1) is a known DNA exonuclease involved in autoimmune disorders and the antiviral response. In this work, we show that TREX1 is also a RNA exonuclease. Purified TREX1 displays robust exoribonuclease activity that degrades single-stranded, but not double-stranded, RNA. TREX1-D200N, an Aicardi-Goutieres syndrome disease-causing mutant, is defective in degrading RNA. TREX1 activity is strongly inhibited by a stretch of pyrimidine residues as is a bacterial homolog, RNase T. Kinetic measurements indicate that the apparent Km of TREX1 for RNA is higher than that for DNA. Like RNase T, human TREX1 is active in degrading native tRNA …

Gene Expression Profiling Identifies Irf4-Associated Molecular Signatures In Hematological Malignancies, Ling Wang, Zhi Q. Yao, Jonathan P. Moorman, Yanji Xu, Shunbin Ning

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The lymphocyte-specific transcription factor Interferon (IFN) Regulatory Factor 4 (IRF4) is implicated in certain types of lymphoid and myeloid malignancies. However, the molecular mechanisms underlying its interactions with these malignancies are largely unknown. In this study, we have first profiled molecular signatures associated with IRF4 expression in associated cancers, by analyzing existing gene expression profiling datasets. Our results show that IRF4 is overexpressed in melanoma, in addition to previously reported contexts including leukemia, myeloma, and lymphoma, and that IRF4 is associated with a unique gene expression pattern in each context. A pool of important genes involved in B-cell development, oncogenesis, …