scholarly journals Loss of a Tyrosine-Dependent Trafficking Motif in the Simian Immunodeficiency Virus Envelope Cytoplasmic Tail Spares Mucosal CD4 Cells but Does Not Prevent Disease Progression

2012 ◽  
Vol 87 (3) ◽  
pp. 1528-1543 ◽  
Author(s):  
Matthew W. Breed ◽  
Andrea P. O. Jordan ◽  
Pyone P. Aye ◽  
Cornelis F. Lichtveld ◽  
Cecily C. Midkiff ◽  
...  
Keyword(s):  
T Cells ◽  
Disease Progression ◽  
Simian Immunodeficiency Virus ◽  
Lamina Propria ◽  
T Cell Activation ◽  
Immune Activation ◽  
Cell Activation ◽  
Cytoplasmic Tail ◽  
Microbial Translocation ◽  
Immunodeficiency Virus

ABSTRACTA hallmark of pathogenic simian immunodeficiency virus (SIV) and human immunodeficiency virus (HIV) infections is the rapid and near-complete depletion of mucosal CD4+T lymphocytes from the gastrointestinal tract. Loss of these cells and disruption of epithelial barrier function are associated with microbial translocation, which has been proposed to drive chronic systemic immune activation and disease progression. Here, we evaluate in rhesus macaques a novel attenuated variant of pathogenic SIVmac239, termed ΔGY, which contains a deletion of a Tyr and a proximal Gly from a highly conserved YxxØ trafficking motif in the envelope cytoplasmic tail. Compared to SIVmac239, ΔGY established a comparable acute peak of viremia but only transiently infected lamina propria and caused little or no acute depletion of mucosal CD4+T cells and no detectable microbial translocation. Nonetheless, these animals developed T-cell activation and declining peripheral blood CD4+T cells and ultimately progressed with clinical or pathological features of AIDS. ΔGY-infected animals also showed no infection of macrophages or central nervous system tissues even in late-stage disease. Although the ΔGY mutation persisted, novel mutations evolved, including the formation of new YxxØ motifs in two of four animals. These findings indicate that disruption of this trafficking motif by the ΔGY mutation leads to a striking alteration in anatomic distribution of virus with sparing of lamina propria and a lack of microbial translocation. Because these animals exhibited wild-type levels of acute viremia and immune activation, our findings indicate that these pathological events are dissociable and that immune activation unrelated to gut damage can be sufficient for the development of AIDS.

scholarly journals Simian Immunodeficiency Virus Nef Protein Delays the Progression of CD4+ T Cells through G1/S Phase of the Cell Cycle

2002 ◽  
Vol 76 (8) ◽  
pp. 3587-3595 ◽  
Author(s):  
Thomas Ndolo ◽  
Navdeep K. Dhillon ◽  
Hau Nguyen ◽  
Moraima Guadalupe ◽  
Maria Mudryj ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Simian Immunodeficiency Virus ◽  
T Cell Activation ◽  
Cell Activation ◽  
Apoptotic Cell ◽  
S Phase ◽  
Immunodeficiency Virus

ABSTRACT Human and simian immunodeficiency virus (HIV and SIV, respectively) infections are characterized by gradual depletion of CD4+ T cells. The underlying mechanisms of CD4+ T-cell depletion and HIV and SIV persistence are not fully determined. The Nef protein is expressed early in infection and is necessary for pathogenesis. Nef can cause T-cell activation and downmodulates cell surface signaling molecules. However, the effect of Nef on the cell cycle has not been well characterized. To determine the role of Nef in the cell cycle, we investigated whether the SIV Nef protein can modulate cell proliferation and apoptosis in CD4+ Jurkat T cells. We developed a CD4+ Jurkat T-cell line that stably expresses SIV Nef under the control of an inducible promoter. Alterations in cell proliferation were determined by flow cytometry using stable intracytoplasmic fluorescent dye 5- and 6-carboxyfluorescein diacetate succinimidyl ester and bromodeoxyuridine incorporation. Apoptotic cell death was measured by annexin V and propidium iodide staining. Our results demonstrated that SIV Nef inhibited Fas-induced apoptosis in these cells and that the mechanism involved upregulation of the Bcl-2 protein. SIV Nef suppressed CD4+ T-cell proliferation by inhibiting the progression of cells into S phase of the cell cycle. Suppression involved an upregulation of cyclin-dependent kinase inhibitors p21 and p27 and the downregulation of cyclin D1 and cyclin A. In summary, inhibition of apoptosis by Nef can lead to persistence of infected cells and can support viral replication. In addition, a Nef-mediated delay in cell cycle progression may contribute to CD4+ T-cell anergy/depletion seen in HIV and SIV disease.

scholarly journals Short-Lived Infected Cells Support Virus Replication in Sooty Mangabeys Naturally Infected with Simian Immunodeficiency Virus: Implications for AIDS Pathogenesis

2008 ◽  
Vol 82 (7) ◽  
pp. 3725-3735 ◽  
Author(s):  
Shari N. Gordon ◽  
Richard M. Dunham ◽  
Jessica C. Engram ◽  
Jacob Estes ◽  
Zichun Wang ◽  
...  
Keyword(s):  
T Cells ◽  
Life Span ◽  
Simian Immunodeficiency Virus ◽  
Virus Replication ◽  
T Cell Activation ◽  
Cell Activation ◽  
Average Life Span ◽  
Immunodeficiency Virus ◽  
Sooty Mangabeys ◽  
Infected Cells

ABSTRACT Sooty mangabeys (SMs) naturally infected with simian immunodeficiency virus (SIV) do not develop AIDS despite high levels of virus replication. At present, the mechanisms underlying this disease resistance are poorly understood. Here we tested the hypothesis that SIV-infected SMs avoid immunodeficiency as a result of virus replication occurring in infected cells that live significantly longer than human immunodeficiency virus (HIV)-infected human cells. To this end, we treated six SIV-infected SMs with potent antiretroviral therapy (ART) and longitudinally measured the decline in plasma viremia. We applied the same mathematical models used in HIV-infected individuals and observed that SMs naturally infected with SIV also present a two-phase decay of viremia following ART, with the bulk (92 to 99%) of virus replication sustained by short-lived cells (average life span, 1.06 days), and only 1 to 8% occurring in longer-lived cells. In addition, we observed that ART had a limited impact on CD4+ T cells and the prevailing level of T-cell activation and proliferation in SIV-infected SMs. Collectively, these results suggest that in SIV-infected SMs, similar to HIV type 1-infected humans, short-lived activated CD4+ T cells, rather than macrophages, are the main source of virus production. These findings indicate that a short in vivo life span of infected cells is a common feature of both pathogenic and nonpathogenic primate lentivirus infections and support a model for AIDS pathogenesis whereby the direct killing of infected cells by HIV is not the main determinant of disease progression.

scholarly journals Costimulatory Pathways in Lymphocyte Proliferation Induced by the Simian Immunodeficiency Virus SIVsmmPBj14

1998 ◽  
Vol 72 (7) ◽  
pp. 6155-6158 ◽  
Author(s):  
Linda Whetter ◽  
Francis J. Novembre ◽  
Michelle Saucier ◽  
Suryaram Gummuluru ◽  
Stephen Dewhurst
Keyword(s):  
Cell Proliferation ◽  
T Cells ◽  
T Cell ◽  
Simian Immunodeficiency Virus ◽  
T Cell Activation ◽  
Lymphocyte Proliferation ◽  
Cell Activation ◽  
Specific Inhibitor ◽  
T Cell Proliferation ◽  
Immunodeficiency Virus

ABSTRACT The PBj14 isolate of the simian immunodeficiency virus SIVsmmPBj14 is unique among primate lentiviruses in its ability to induce lymphocyte proliferation and acutely lethal disease. The studies reported here show that viral induction of T-cell proliferation requires accessory cells, such as primary monocytes or Raji B-lymphoma cells, as well as the presence of a putative immunoreceptor tyrosine-based activation motif within the viral Nef protein. Addition of CTLA4-immunoglobulin fusion protein or anti-B7 antibodies to virally infected T cells led to substantial, but not complete, inhibition of monocyte-costimulated T-cell proliferation—suggesting that both CD28/B7-dependent and non-CD28-dependent pathways may contribute to the costimulation of virally induced lymphoproliferation. Finally, cyclosporin A, a specific inhibitor of the calcium-calmodulin-regulated phosphatase activity of calcineurin, which influences activation of the transcription factor nuclear factor of activated T cells, was shown to block virally mediated T-cell proliferation. Taken together, these findings suggest that the effect of SIVsmmPBj14 on T-cell activation may be functionally analogous, at least in part, to the effect of engagement of the T-cell receptor.

scholarly journals The Quality of Chimpanzee T-Cell Activation and Simian Immunodeficiency Virus/Human Immunodeficiency Virus Susceptibility Achieved via Antibody-Mediated T-Cell Receptor/CD3 Stimulation Is a Function of the Anti-CD3 Antibody Isotype

2008 ◽  
Vol 82 (20) ◽  
pp. 10271-10278 ◽  
Author(s):  
Frederic Bibollet-Ruche ◽  
Brett A. McKinney ◽  
Alexandra Duverger ◽  
Frederic H. Wagner ◽  
Aftab A. Ansari ◽  
...  
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
T Cell ◽  
Simian Immunodeficiency Virus ◽  
T Cell Activation ◽  
Cell Activation ◽  
Cell Receptor ◽  
Antibody Isotype ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT While human immunodeficiency virus type 1 (HIV-1) infection is associated with hyperimmune activation and systemic depletion of CD4+ T cells, simian immunodeficiency virus (SIV) infection in sooty mangabeys or chimpanzees does not exhibit these hallmarks. Control of immune activation is thought to be one of the major components that govern species-dependent differences in the disease pathogenesis. A previous study introduced the idea that the resistance of chimpanzees to SIVcpz infection-induced hyperimmune activation could be the result of the expression of select sialic acid-recognizing immunoglobulin (Ig)-like lectin (Siglec) superfamily members by chimpanzee T cells. Siglecs, which are absent on human T cells, were thought to control levels of T-cell activation in chimpanzees and were thus suggested as a cause for the pathogenic differences in the course of SIVcpz or HIV-1 infection. As in human models of T-cell activation, stimulation had been attempted using an anti-CD3 monoclonal antibody (MAb) (UCHT1; isotype IgG1), but despite efficient binding, UCHT1 failed to activate chimpanzee T cells, an activation block that could be partially overcome by MAb-induced Siglec-5 internalization. We herein demonstrate that anti-CD3 MAb-mediated chimpanzee T-cell activation is a function of the anti-CD3 MAb isotype and is not governed by Siglec expression. While IgG1 anti-CD3 MAbs fail to stimulate chimpanzee T cells, IgG2a anti-CD3 MAbs activate chimpanzee T cells in the absence of Siglec manipulations. Our results thus imply that prior to studying possible differences between human and chimpanzee T-cell activation, a relevant model of chimpanzee T cell activation needs to be established.

scholarly journals Longitudinal Examination of the Intestinal Lamina Propria Cellular Compartment of Simian Immunodeficiency Virus-Infected Rhesus Macaques Provides Broader and Deeper Insights into the Link between Aberrant MicroRNA Expression and Persistent Immune Activation

2016 ◽  
Vol 90 (10) ◽  
pp. 5003-5019 ◽  
Author(s):  
Vinay Kumar ◽  
Workineh Torben ◽  
Carys S. Kenway ◽  
Faith R. Schiro ◽  
Mahesh Mohan
Keyword(s):  
T Cell ◽  
Lamina Propria ◽  
T Cell Activation ◽  
Immune Activation ◽  
Cell Activation ◽  
Critical Role ◽  
Intestinal Lamina Propria ◽  
Immunodeficiency Virus ◽  
Siv Infection

ABSTRACTChronic immune activation/inflammation driven by factors like microbial translocation is a key determinant of human immunodeficiency virus/simian immunodeficiency virus (HIV/SIV) disease progression. Although extensive research on inflammation has focused on studying protein regulators, increasing evidence suggests a critical role for microRNAs (miRNAs) in regulating several aspects of the immune/inflammatory response and immune cell proliferation, differentiation, and activation. To understand their immunoregulatory role, we profiled miRNA expression sequentially in intestinal lamina propria leukocytes (LPLs) of eight macaques before and at 21, 90, and 180 days postinfection (dpi). At 21 dpi, ∼20 and 9 miRNAs were up- and downregulated, respectively. However, at 90 dpi (n= 60) and 180 dpi (n= 44), ≥75% of miRNAs showed decreased expression. Notably, the T-cell activation-associated miR-15b, miR-142-3p, miR-142-5p, and miR-150 expression was significantly downregulated at 90 and 180 dpi. Out of ∼10 downregulated miRNAs predicted to regulate CD69, we confirmed miR-92a to directly target CD69. Interestingly, the SIV-induced miR-190b expression was elevated at all time points. Additionally, elevated lipopolysaccharide (LPS)-responsive miR-146b-5p expression at 180 dpi was confirmed in primary intestinal macrophages following LPS treatmentin vitro. Further, reporter and overexpression assays validated IRAK1 (interleukin-1 receptor 1 kinase) as a direct miR-150 target. Furthermore, IRAK1 protein levels were markedly elevated in intestinal LPLs and epithelium. Finally, blockade of CD8+T-cell activation/proliferation with delta-9 tetrahydrocannabinol (Δ9-THC) significantly prevented miR-150 downregulation and IRAK1 upregulation. Our findings suggest that miR-150 downregulation during T-cell activation disrupts the translational control of IRAK1, facilitating persistent gastrointestinal (GI) inflammation. Finally, the ability of Δ9-THC to block the miR-150-IRAK1 regulatory cascade highlights the potential of cannabinoids to inhibit persistent inflammation/immune activation in HIV/SIV infection.IMPORTANCEPersistent GI tract disease/inflammation is a cardinal feature of HIV/SIV infection. Increasing evidence points to a critical role for miRNAs in controlling several aspects of the immune/inflammatory response. Here, we show significant dysregulation of miRNA expression exclusively in the intestinal lamina propria cellular compartment through the course of SIV infection. Specifically, the study identified miRNA signatures associated with key pathogenic events, such as viral replication, T-cell activation, and microbial translocation. The T-cell-enriched miR-150 showed significant downregulation throughout SIV infection and was confirmed to target IRAK1, a critical signal-transducing component of the IL-1 receptor and TLR signaling pathways. Reduced miR-150 expression was associated with markedly elevated IRAK1 expression in the intestines of chronically SIV-infected macaques. Finally, Δ9-THC-mediated blockade of CD8+T-cell activationin vitrosignificantly inhibited miR-150 downregulation and IRAK1 upregulation, suggesting its potential for targeted immune modulation in HIV infection.

scholarly journals Deep immune profiling of MIS-C demonstrates marked but transient immune activation compared to adult and pediatric COVID-19

2021 ◽  
Vol 6 (57) ◽  
pp. eabf7570
Author(s):  
Laura A. Vella ◽  
Josephine R. Giles ◽  
Amy E. Baxter ◽  
Derek A. Oldridge ◽  
Caroline Diorio ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
T Cell Activation ◽  
Cd8 T Cells ◽  
Immune Activation ◽  
Cell Activation ◽  
Vascular Complications ◽  
Adult Disease ◽  
Vasoactive Medication ◽  
Inflammatory Syndrome

Pediatric COVID-19 following SARS-CoV-2 infection is associated with fewer hospitalizations and often milder disease than in adults. A subset of children, however, present with Multisystem Inflammatory Syndrome in Children (MIS-C) that can lead to vascular complications and shock, but rarely death. The immune features of MIS-C compared to pediatric COVID-19 or adult disease remain poorly understood. We analyzed peripheral blood immune responses in hospitalized SARS-CoV-2 infected pediatric patients (pediatric COVID-19) and patients with MIS-C. MIS-C patients had patterns of T cell-biased lymphopenia and T cell activation similar to severely ill adults, and all patients with MIS-C had SARS-CoV-2 spike-specific antibodies at admission. A distinct feature of MIS-C patients was robust activation of vascular patrolling CX3CR1+ CD8+ T cells that correlated with the use of vasoactive medication. Finally, whereas pediatric COVID-19 patients with acute respiratory distress syndrome (ARDS) had sustained immune activation, MIS-C patients displayed clinical improvement over time, concomitant with decreasing immune activation. Thus, non-MIS-C versus MIS-C SARS-CoV-2 associated illnesses are characterized by divergent immune signatures that are temporally distinct from one another and implicate CD8+ T cells in the clinical presentation and trajectory of MIS-C.

scholarly journals Cytomegalovirus Replication in Semen Is Associated with Higher Levels of Proviral HIV DNA and CD4+T Cell Activation during Antiretroviral Treatment

2014 ◽  
Vol 88 (14) ◽  
pp. 7818-7827 ◽  
Author(s):  
Sara Gianella ◽  
Marta Massanella ◽  
Douglas D. Richman ◽  
Susan J. Little ◽  
Celsa A. Spina ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell Activation ◽  
Immune Activation ◽  
Genital Tract ◽  
Cell Activation ◽  
Future Studies ◽  
Hiv Rna ◽  
Hiv Dna ◽  
Dna Reservoir

ABSTRACTAsymptomatic cytomegalovirus (CMV) replication occurs frequently in the genital tract in untreated HIV-infected men and is associated with increased immune activation and HIV disease progression. To determine the connections between CMV-associated immune activation and the size of the viral reservoir, we evaluated the interactions between (i) asymptomatic seminal CMV replication, (ii) levels of T cell activation and proliferation in blood, and (iii) the size and transcriptional activity of the HIV DNA reservoir in blood from 53 HIV-infected men on long-term antiretroviral therapy (ART) with suppressed HIV RNA in blood plasma. We found that asymptomatic CMV shedding in semen was associated with significantly higher levels of proliferating and activated CD4+T cells in blood (P< 0.01). Subjects with detectable CMV in semen had approximately five times higher average levels of HIV DNA in blood CD4+T cells than subjects with no CMV. There was also a trend for CMV shedders to have increased cellular (multiply spliced) HIV RNA transcription (P= 0.068) compared to participants without CMV, but it is unclear if this transcription pattern is associated with residual HIV replication. In multivariate analysis, the presence of seminal plasma CMV (P= 0.04), detectable 2-long terminal repeat (2-LTR), and lower nadir CD4+(P< 0.01) were independent predictors of higher levels of proviral HIV DNA in blood. Interventions aimed at reducing seminal CMV and associated immune activation may be important for HIV curative strategies. Future studies of anti-CMV therapeutics will help to establish causality and determine the mechanisms underlying these described associations.IMPORTANCEAlmost all individuals infected with HIV are also infected with cytomegalovirus (CMV), and the replication dynamics of the two viruses likely influence each other. This study investigated interactions between asymptomatic CMV replication within the male genital tract, levels of inflammation in blood, and the size of the HIV DNA reservoir in 53 HIV-infected men on long-term antiretroviral therapy (ART) with suppressed HIV RNA in blood plasma. In support of our primary hypothesis, shedding of CMV DNA in semen was associated with increased activation and proliferation of T cells in blood and also significantly higher levels of HIV DNA in blood cells. These results suggest that CMV reactivation might play a role in the maintenance of the HIV DNA reservoir during suppressive ART and that it could be a target of pharmacologic intervention in future studies.

scholarly journals Loss of Naïve Cells Accompanies Memory CD4+ T-Cell Depletion during Long-Term Progression to AIDS in Simian Immunodeficiency Virus-Infected Macaques

2006 ◽  
Vol 81 (2) ◽  
pp. 893-902 ◽  
Author(s):  
Yoshiaki Nishimura ◽  
Tatsuhiko Igarashi ◽  
Alicia Buckler-White ◽  
Charles Buckler ◽  
Hiromi Imamichi ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Disease Progression ◽  
Simian Immunodeficiency Virus ◽  
Peripheral Blood ◽  
Acute Infection ◽  
Virus Production ◽  
Recovery Phase ◽  
Lymphoid Tissues ◽  
Immunodeficiency Virus

ABSTRACT Human immunodeficiency virus and simian immunodeficiency virus (SIV) induce a slow progressive disease, characterized by the massive loss of memory CD4+ T cells during the acute infection followed by a recovery phase in which virus replication is partially controlled. However, because the initial injury is so severe and virus production persists, the immune system eventually collapses and a symptomatic fatal disease invariably occurs. We have assessed CD4+ T-cell dynamics and disease progression in 12 SIV-infected rhesus monkeys for nearly 2 years. Three macaques exhibiting a rapid progressor phenotype experienced rapid and irreversible loss of memory, but not naïve, CD4+ T lymphocytes from peripheral blood and secondary lymphoid tissues and died within the first 6 months of virus inoculation. In contrast, SIV-infected conventional progressor animals sustained marked but incomplete depletions of memory CD4+ T cells and continuous activation/proliferation of this T-lymphocyte subset. This was associated with a profound loss of naïve CD4+ T cells from peripheral blood and secondary lymphoid tissues, which declined at rates that correlated with disease progression. These data suggest that the persistent loss of memory CD4+T cells, which are being eliminated by direct virus killing and activation-induced cell death, requires the continuous differentiation of naïve into memory CD4+ T cells. This unrelenting replenishment process eventually leads to the exhaustion of the naïve CD4+T-cell pool and the development of disease.

scholarly journals Identification of distinct immune activation profiles in adult humans

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Renaud Cezar ◽  
Audrey Winter ◽  
Delphine Desigaud ◽  
Manuela Pastore ◽  
Lucy Kundura ◽  
...  
Keyword(s):  
T Cells ◽  
Immune Activation ◽  
Cell Activation ◽  
Immune Cell ◽  
Nk Cell ◽  
Liver Steatosis ◽  
Treg Cells ◽  
Microbial Translocation ◽  
Color Flow

AbstractLatent infectious agents, microbial translocation, some metabolites and immune cell subpopulations, as well as senescence modulate the level and quality of activation of our immune system. Here, we tested whether various in vivo immune activation profiles may be distinguished in a general population. We measured 43 markers of immune activation by 8-color flow cytometry and ELISA in 150 adults, and performed a double hierarchical clustering of biomarkers and volunteers. We identified five different immune activation profiles. Profile 1 had a high proportion of naïve T cells. By contrast, Profiles 2 and 3 had an elevated percentage of terminally differentiated and of senescent CD4+ T cells and CD8+ T cells, respectively. The fourth profile was characterized by NK cell activation, and the last profile, Profile 5, by a high proportion of monocytes. In search for etiologic factors that could determine these profiles, we observed a high frequency of naïve Treg cells in Profile 1, contrasting with a tendency to a low percentage of Treg cells in Profiles 2 and 3. Moreover, Profile 5 tended to have a high level of 16s ribosomal DNA, a direct marker of microbial translocation. These data are compatible with a model in which specific causes, as the frequency of Treg or the level of microbial translocation, shape specific profiles of immune activation. It will be of interest to analyze whether some of these profiles drive preferentially some morbidities known to be fueled by immune activation, as insulin resistance, atherothrombosis or liver steatosis.

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