The Activating Receptors of Natural Killer Cells and Their Inter-Switching Potentials

2020 ◽  
Vol 21 (16) ◽  
pp. 1733-1751
Author(s):  
Adekunle Babajide Rowaiye ◽  
Titilayo Asala ◽  
Angus Nnamdi Oli ◽  
Ikemefuna Chijioke Uzochukwu ◽  
Alex Akpa ◽  
...  
Keyword(s):  
Small Molecules ◽  
Tnf Alpha ◽  
Signal Pathways ◽  
Binding Affinities ◽  
Activation Threshold ◽  
Effector Functions ◽  
Activating Receptors ◽  
Direct Cytotoxicity ◽  
Infected Cells ◽  
Transduction Signal

The global incidence of cancer is on the increase and researchers are prospecting for specific and non-selective therapies derived from the immune system. The killer activating receptors of NK cells are known to be involved in immunosurveillance against tumor and virally-infected cells. These receptors belong to two main categories, namely the immunoglobulin like and C-lectin like families. Though they have different signal pathways, all the killer activating receptors have similar effector functions which include direct cytotoxicity and the release of inflammatory cytokines such as IFN-gamma and TNF-alpha. To transduce signals that exceed the activation threshold for cytotoxicity, most of these receptors require synergistic effort. This review profiles 21 receptors: 13 immunoglobulin-like, 5 lectin-like, and 3 others. It critically explores their structural uniqueness, role in disease, respective transduction signal pathways and their status as current and prospective targets for cancer immunotherapy. While the native ligands of most of these receptors are known, much work is required to prospect for specific antibodies, peptides and multi-target small molecules with high binding affinities.

scholarly journals Nonameric Peptide Orchestrates Signal Transduction in the Activating HLA-E/NKG2C/CD94 Immune Complex as Revealed by All-Atom Simulations

2021 ◽  
Vol 22 (13) ◽  
pp. 6670
Author(s):  
Eva Prašnikar ◽  
Andrej Perdih ◽  
Jure Borišek
Keyword(s):  
Signal Transduction ◽  
Cell Activation ◽  
Nk Cell ◽  
Innate Immune ◽  
Target Cells ◽  
Molecular Events ◽  
Activating Receptors ◽  
Molecular Machinery ◽  
Infected Cells ◽  
Bond Network

The innate immune system’s natural killer (NK) cells exert their cytolytic function against a variety of pathological challenges, including tumors and virally infected cells. Their activation depends on net signaling mediated via inhibitory and activating receptors that interact with specific ligands displayed on the surfaces of target cells. The CD94/NKG2C heterodimer is one of the NK activating receptors and performs its function by interacting with the trimeric ligand comprised of the HLA-E/β2m/nonameric peptide complex. Here, simulations of the all-atom multi-microsecond molecular dynamics in five immune complexes provide atomistic insights into the receptor–ligand molecular recognition, as well as the molecular events that facilitate the NK cell activation. We identify NKG2C, the HLA-Eα2 domain, and the nonameric peptide as the key elements involved in the molecular machinery of signal transduction via an intertwined hydrogen bond network. Overall, the study addresses the complex intricacies that are necessary to understand the mechanisms of the innate immune system.

Influence of Human Serum Albumin Glycation on the Binding Affinities for Natural Flavonoids

2019 ◽  
Vol 17 (1) ◽  
pp. 806-812
Author(s):  
Liangliang Liu ◽  
Yi Liu ◽  
Aiping Xiao ◽  
Shiyong Mei ◽  
Yixi Xie
Keyword(s):  
Human Serum Albumin ◽  
Serum Albumin ◽  
Human Serum ◽  
Small Molecules ◽  
Human Body ◽  
Binding Sites ◽  
Plasma Proteins ◽  
Fluorescence Spectra ◽  
Binding Affinities ◽  
Dietary Flavonoids

AbstractIncreasing the degree of glycation in diabetes could affect the ability of plasma proteins in binding to small molecules and active compounds. In this study, the influence of glycation of Human serum albumin (HSA) on the binding affinities for six dietary flavonoids was investigated by fluorescence spectra. Glycated HSA was prepared through incubation with glucose and characterized by several methods to confirm the glycation. It was found that the level of glycation increased with the increasing incubation time. The glycation of HSA increased the binding affinities for flavonoids by 1.40 to 48.42 times, which indicates that modifications caused by the glycation may have different influences on the interactions of flavonoids with HSA at separate binding sites on this protein. These results are valuable for understanding the influence of diabetes on the metabolism of flavonoids and other bioactive small molecules in human body.

scholarly journals Probing the interaction of nanoparticles with small molecules in real time via quartz crystal microbalance monitoring

Nanoscale ◽  
2019 ◽  
Vol 11 (23) ◽  
pp. 11107-11113 ◽  
Author(s):  
Ye Yang ◽  
Guillaume Poss ◽  
Yini Weng ◽  
Runzhang Qi ◽  
Hanrui Zheng ◽  
...  
Keyword(s):  
Small Molecules ◽  
Real Time ◽  
Quartz Crystal Microbalance ◽  
Quartz Crystal ◽  
Binding Affinities ◽  
Target Analytes

We report on a novel screening route to obtain quantitative measures for nanoparticle binding affinities to target analytes.

scholarly journals Toll-Like Receptor 7 Agonist GS-9620 Induces HIV Expression and HIV-Specific Immunity in Cells from HIV-Infected Individuals on Suppressive Antiretroviral Therapy

2017 ◽  
Vol 91 (8) ◽  
Author(s):  
Angela Tsai ◽  
Alivelu Irrinki ◽  
Jasmine Kaur ◽  
Tomas Cihlar ◽  
George Kukolj ◽  
...  
Keyword(s):  
Antiretroviral Therapy ◽  
Mononuclear Cells ◽  
Antiviral Immunity ◽  
Type I ◽  
Toll Like Receptor ◽  
Peripheral Blood Mononuclear ◽  
Effector Functions ◽  
Latently Infected ◽  
Infected Cells ◽  
Latent Hiv

ABSTRACT Antiretroviral therapy can suppress HIV replication to undetectable levels but does not eliminate latent HIV, thus necessitating lifelong therapy. Recent efforts to target this persistent reservoir have focused on inducing the expression of latent HIV so that infected cells may be recognized and eliminated by the immune system. Toll-like receptor (TLR) activation stimulates antiviral immunity and has been shown to induce HIV from latently infected cells. Activation of TLR7 leads to the production of several stimulatory cytokines, including type I interferons (IFNs). In this study, we show that the selective TLR7 agonist GS-9620 induced HIV in peripheral blood mononuclear cells (PBMCs) from HIV-infected individuals on suppressive antiretroviral therapy. GS-9620 increased extracellular HIV RNA 1.5- to 2-fold through a mechanism that required type I IFN signaling. GS-9620 also activated HIV-specific T cells and enhanced antibody-mediated clearance of HIV-infected cells. Activation by GS-9620 in combination with HIV peptide stimulation increased CD8 T cell degranulation, production of intracellular cytokines, and cytolytic activity. T cell activation was again dependent on type I IFNs produced by plasmacytoid dendritic cells. GS-9620 induced phagocytic cell maturation and improved effector-mediated killing of HIV-infected CD4 T cells by the HIV envelope-specific broadly neutralizing antibody PGT121. Collectively, these data show that GS-9620 can activate HIV production and improve the effector functions that target latently infected cells. GS-9620 may effectively complement orthogonal therapies designed to stimulate antiviral immunity, such as therapeutic vaccines or broadly neutralizing antibodies. Clinical studies are under way to determine if GS-9620 can target HIV reservoirs. IMPORTANCE Though antiretroviral therapies effectively suppress viral replication, they do not eliminate integrated proviral DNA. This stable intermediate of viral infection is persistently maintained in reservoirs of latently infected cells. Consequently, lifelong therapy is required to maintain viral suppression. Ultimately, new therapies that specifically target and eliminate the latent HIV reservoir are needed. Toll-like receptor agonists are potent enhancers of innate antiviral immunity that can also improve the adaptive immune response. Here, we show that a highly selective TLR7 agonist, GS-9620, activated HIV from peripheral blood mononuclear cells isolated from HIV-infected individuals with suppressed infection. GS-9620 also improved immune effector functions that specifically targeted HIV-infected cells. Previously published studies on the compound in other chronic viral infections show that it can effectively induce immune activation at safe and tolerable clinical doses. Together, the results of these studies suggest that GS-9620 may be useful for treating HIV-infected individuals on suppressive antiretroviral therapy.

scholarly journals Antibodies Elicited by an NS1-Based Vaccine Protect Mice against Zika Virus

mBio ◽  
2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Mark J. Bailey ◽  
Felix Broecker ◽  
James Duehr ◽  
Fortuna Arumemi ◽  
Florian Krammer ◽  
...  
Keyword(s):  
Virus Vaccine ◽  
Zika Virus ◽  
Envelope Glycoprotein ◽  
Congenital Malformations ◽  
Ns1 Protein ◽  
Specific Antibodies ◽  
Antibody Dependent Enhancement ◽  
Effector Functions ◽  
Protective Antibodies ◽  
Infected Cells

ABSTRACTZika virus is a mosquito-borne flavivirus which can cause severe disease in humans, including microcephaly and other congenital malformations in newborns and Guillain-Barré syndrome in adults. There are currently no approved prophylactics or therapeutics for Zika virus; the development of a safe and effective vaccine is an urgent priority. Preclinical studies suggest that the envelope glycoprotein can elicit potently neutralizing antibodies. However, such antibodies are implicated in the phenomenon of antibody-dependent enhancement of disease. We have previously shown that monoclonal antibodies targeting the Zika virus nonstructural NS1 protein are protective without inducing antibody-dependent enhancement of disease. Here, we investigated whether the NS1 protein itself is a viable vaccine target. Wild-type mice were vaccinated with an NS1-expressing DNA plasmid followed by two adjuvanted protein boosters, which elicited high antibody titers. Passive transfer of the immune sera was able to significantly protect STAT2 knockout mice against lethal challenge by Zika virus. In addition, long-lasting NS1-specific IgG responses were detected in serum samples from patients in either the acute or the convalescent phase of Zika virus infection. These NS1-specific antibodies were able to functionally engage Fcγ receptors. In contrast, envelope-specific antibodies did not activate Fc-mediated effector functions on infected cells. Our data suggest that the Zika virus NS1 protein, which is expressed on infected cells, is critical for Fc-dependent cell-mediated immunity. The present study demonstrates that the Zika virus NS1 protein is highly immunogenic and can elicit protective antibodies, underscoring its potential for an effective Zika virus vaccine.IMPORTANCEZika virus is a global public health threat that causes microcephaly and congenital malformations in newborns and Guillain-Barré syndrome in adults. Currently, no vaccines or treatments are available. While antibodies targeting the envelope glycoprotein can neutralize virus, they carry the risk of antibody-dependent enhancement of disease (ADE). In contrast, antibodies generated against the NS1 protein can be protective without eliciting ADE. The present study demonstrates the effectiveness of an NS1-based vaccine in eliciting high titers of protective antibodies against Zika virus disease in a mouse model. Sera generated by this vaccine can elicit Fc-mediated effector functions against Zika virus-infected cells. Lastly, we provide human data suggesting that the antibody response against the Zika virus NS1 protein is long-lasting and functionally active. Overall, our work will inform the development of a safe and effective Zika virus vaccine.

scholarly journals Targeting the GRP78-Dependant SARS-CoV-2 Cell Entry by Peptides and Small Molecules

2020 ◽  
Vol 14 ◽  
pp. 117793222096550
Author(s):  
Loubna Allam ◽  
Fatima Ghrifi ◽  
Hakmi Mohammed ◽  
Naima El Hafidi ◽  
Rachid El Jaoudi ◽  
...  
Keyword(s):  
Small Molecules ◽  
Binding Sites ◽  
Epigallocatechin Gallate ◽  
Host Cells ◽  
Spike Protein ◽  
Target Cells ◽  
Binding Affinities ◽  
Rapid Spread ◽  
Inhibitor Compounds ◽  
Potential Inhibitors

The global burden of infections and the rapid spread of viral diseases show the need for new approaches in the prevention and development of effective therapies. To this end, we aimed to explore novel inhibitor compounds that can stop replication or decrease the viral load of the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), for which there is currently no approved treatment. Besides using the angiotensin-converting enzyme (ACE2) receptor as a main gate, the CoV-2 can bind to the glucose-regulating protein 78 (GRP78) receptor to get into the cells to start an infection. Here, we report potential inhibitors comprising small molecules and peptides that could interfere with the interaction of SARS-CoV-2 and its target cells by blocking the recognition of the GRP78 cellular receptor by the viral Spike protein. These inhibitors were discovered through an approach of in silico screening of available databases of bioactive peptides and polyphenolic compounds and the analysis of their docking modes. This process led to the selection of 9 compounds with optimal binding affinities to the target sites. The peptides (satpdb18674, satpdb18446, satpdb12488, satpdb14438, and satpdb28899) act on regions III and IV of the viral Spike protein and on its binding sites in GRP78. However, 4 polyphenols such as epigallocatechin gallate (EGCG), homoeriodictyol, isorhamnetin, and curcumin interact, in addition to the Spike protein and its binding sites in GRP78, with the ATPase domain of GRP78. Our work demonstrates that there are at least 2 approaches to block the spread of SARS-CoV-2 by preventing its fusion with the host cells via GRP78.

An ABSINTH-Based Protocol for Predicting Binding Affinities between Proteins and Small Molecules

2020 ◽  
Vol 60 (10) ◽  
pp. 5188-5202
Author(s):  
Jean-Rémy Marchand ◽  
Tim Knehans ◽  
Amedeo Caflisch ◽  
Andreas Vitalis
Keyword(s):  
Small Molecules ◽  
Binding Affinities

scholarly journals NK cell–activating receptors require PKC-θ for sustained signaling, transcriptional activation, and IFN-γ secretion

Blood ◽  
2008 ◽  
Vol 112 (10) ◽  
pp. 4109-4116 ◽  
Author(s):  
Ilaria Tassi ◽  
Marina Cella ◽  
Rachel Presti ◽  
Angela Colucci ◽  
Susan Gilfillan ◽  
...  
Keyword(s):  
Transcriptional Activation ◽  
Nk Cell ◽  
Cell Secretion ◽  
Surface Receptors ◽  
Intracellular Signals ◽  
Activating Receptors ◽  
Infected Cells ◽  
Multiple Cell ◽  
Ifn Γ ◽  
Extracellular Regulated Kinase

AbstractNatural killer (NK) cell sense virally infected cells and tumor cells through multiple cell surface receptors. Many NK cell–activating receptors signal through immunoreceptor tyrosine–based activation motif (ITAM)–containing adapters, which trigger both cytotoxicy and secretion of interferon-gamma (IFN-γ). Within the ITAM pathway, distinct signaling intermediates are variably involved in cytotoxicity and/or IFN-γ secretion. In this study, we have evaluated the role of protein kinase C-θ (PKC-θ) in NK-cell secretion of lytic mediators and IFN-γ. We found that engagement of NK-cell receptors that signal through ITAMs results in prompt activation of PKC-θ. Analyses of NK cells from PKC-θ–deficient mice indicated that PKC-θ is absolutely required for ITAM-mediated IFN-γ secretion, whereas it has no marked influence on the release of cytolytic mediators. Moreover, we found that PKC-θ deficiency preferentially impairs sustained extracellular-regulated kinase signaling as well as activation of c-Jun N-terminal kinase and the transcription factors AP-1 and NFAT but does not affect activation of NF-κB. These results indicate that NK cell–activating receptors require PKC-θ to generate sustained intracellular signals that reach the nucleus and promote transcriptional activation, ultimately inducing IFN-γ production.

scholarly journals The dynamics of granuloma formation in experimental visceral leishmaniasis.

1988 ◽  
Vol 167 (6) ◽  
pp. 1927-1937 ◽  
Author(s):  
M J McElrath ◽  
H W Murray ◽  
Z A Cohn
Keyword(s):  
T Cells ◽  
Specific Antigen ◽  
Cell Types ◽  
Host Cells ◽  
Cytotoxic Potential ◽  
Sequence Of Events ◽  
Direct Cytotoxicity ◽  
Infected Cells ◽  
Parasite Replication ◽  
Hepatic Granulomas

We have examined the temporal sequence of events leading to the formation of hepatic granulomas after the intravenous injection of L. donovani amastigotes into BALB/c mice. Parasite ingestion by permissive Kupffer cells (KC) occurred promptly, and local KC aggregations were the foci about which granulomas were subsequently formed. Infected KC were recognized by the uptake of colloidal carbon and the expression of the macrophage-specific antigen recognized by F4/80 mAb. Peroxidase-positive granulocytes migrated rapidly and were followed by monocytes and L3T4+ T cells that enclosed the infected KC. Thereafter, Ly-2+ T cells were prominent members of the granulomatous lymphoid population. Parasites multiplied until 4 wk, and then a prompt reduction in infected cells occurred. This was associated with a sharp decline in the L3T4+ T cells of the granulomas and the maintenance of the Ly-2+ subset. In comparison, athymic nu/nu mice developed smaller, more slowly appearing granulomas that contained granulocytes and monocytes and exhibited progressive parasite replication. Upon rechallenge, the entire process was completed in 2 wk, and infected KC in the euthymic mice were never observed. We hypothesize that the effectiveness of the granulomatous response requires the destruction of parasitized host cells (KC), in a lymphokine rich environment. We further suggest that the Ly-2+ T cell serves as an important effector cell in this process, either by direct cytotoxicity or by supporting the cytotoxic potential of other cell types in the granuloma.

scholarly journals Activated B lymphocytes from human immunodeficiency virus-infected individuals induce virus expression in infected T cells and a promonocytic cell line, U1.

1991 ◽  
Vol 173 (1) ◽  
pp. 1-5 ◽  
Author(s):  
P Rieckmann ◽  
G Poli ◽  
J H Kehrl ◽  
A S Fauci
Keyword(s):  
Human Immunodeficiency Virus ◽  
T Cells ◽  
B Cells ◽  
Cell Line ◽  
B Lymphocytes ◽  
Peripheral Blood ◽  
Tnf Alpha ◽  
Necrosis Factor Alpha ◽  
Immunodeficiency Virus ◽  
Infected Cells

Freshly isolated B lymphocytes from patients infected with human immunodeficiency virus (HIV), in contrast to B cells from normal controls, were shown to induce viral expression in two cell lines: ACH-2, a T cell line, and U1, a promonocytic cell line, which are chronically infected with HIV, as well as in autologous T cells. In 10 out of 10 HIV-infected individuals with hypergammaglobulinemia, spontaneous HIV-inductive capacity was found with highly purified peripheral blood B cells, whereas peripheral blood or tonsillar B cells from six healthy, HIV-negative donors did not induce HIV expression unless the cells were stimulated in vitro. The induction of HIV expression was observed in direct coculture experiments of B lymphocytes and HIV-infected cells, and could also be mediated by supernatants from cultures of B cells. Significantly higher amounts of interleukin 6 (IL-6) and tumor necrosis factor alpha (TNF-alpha) were detected in the B cell culture supernatants from HIV-infected patients with hypergammaglobulinemia (IL-6: mean = 536 pg/ml; TNF-alpha: mean = 493 pg/ml), as compared with normal uninfected controls (IL-6: mean = 18 pg/ml; TNF-alpha: mean = 23 pg/ml). Antibodies against these cytokines abolished the HIV-inductive capacity of B cells. We conclude that in vivo activated B cells in HIV-infected individuals can upregulate the expression of virus in infected cells by secreting cytokines such as TNF-alpha and IL-6, and, therefore, may play a role in the progression of HIV infection.

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