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- Anania, Jessica, et al.
(author)
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IgG Suppresses Antibody Responses to Sheep Red Blood Cells in Double Knock-Out Mice Lacking Complement Factor C3 and Activating Fc gamma-Receptors
- 2020
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In: Frontiers in Immunology. - : FRONTIERS MEDIA SA. - 1664-3224. ; 11
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Journal article (peer-reviewed)abstract
- Antigen-specific IgG antibodies, passively administered together with erythrocytes, prevent antibody responses against the erythrocytes. The mechanism behind the suppressive ability of IgG has been the subject of intensive studies, yet there is no consensus as to how it works. An important question is whether the Fc-region of IgG is required. Several laboratories have shown that IgG suppresses equally well in wildtype mice and mice lacking the inhibitory Fc gamma IIB, activating Fc gamma Rs (Fc gamma RI, III, and IV), or complement factor C3. These observations consistently suggest that IgG-mediated suppression does not rely on Fc-mediated antibody functions. However, it was recently shown that anti-KEL sera failed to suppress antibody responses to KEL-expressing transgenic mouse erythrocytes in double knock-out mice lacking both activating Fc gamma Rs and C3. Yet, in the same study, antibody-mediated suppression worked well in each single knock-out strain. This unexpected observation suggested Fc-dependence of IgG-mediated suppression and prompted us to investigate the issue in the classical experimental model using sheep red blood cells (SRBC) as antigen. SRBC alone or IgG anti-SRBC together with SRBC was administered to wildtype and double knock-out mice lacking C3 and activating Fc gamma Rs. IgG efficiently suppressed the IgM and IgG anti-SRBC responses in both mouse strains, thus supporting previous observations that suppression in this model is Fc-independent.
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- Axberg Pålsson, Sandra, et al.
(author)
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Single-Stranded Oligonucleotide-Mediated Inhibition of Respiratory Syncytial Virus Infection
- 2020
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In: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 11
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Journal article (peer-reviewed)abstract
- Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory tract infections in young children. Currently, there is no RSV vaccine or universally accessible antiviral treatment available. Addressing the urgent need for new antiviral agents, we have investigated the capacity of a non-coding single-stranded oligonucleotide (ssON) to inhibit RSV infection. By utilizing a GFP-expressing RSV, we demonstrate that the ssON significantly reduced the proportion of RSV infected A549 cells (lung epithelial cells). Furthermore, we show that ssON's antiviral activity was length dependent and that both RNA and DNA of this class of oligonucleotides have antiviral activity. We reveal that ssON inhibited RSV infection by competing with the virus for binding to the cellular receptor nucleolin in vitro. Additionally, using a recombinant RSV that expresses luciferase we show that ssON effectively blocked RSV infection in mice. Treatment with ssON in vivo resulted in the upregulation of RSV-induced interferon stimulated genes (ISGs) such as Stat1, Stat2, Cxcl10, and Ccl2. This study highlights the possibility of using oligonucleotides as therapeutic agents against RSV infection. We demonstrate that the mechanism of action of ssON is the inhibition of viral entry in vitro, likely through the binding of the receptor, nucleolin and that ssON treatment against RSV infection in vivo additionally results in the upregulation of ISGs.
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- Baruah, Kartik
(author)
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Structure-Functional Activity Relationship of beta-Glucans From the Perspective of Immunomodulation: A Mini-Review
- 2020
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In: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 11
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Research review (peer-reviewed)abstract
- beta-Glucans are a heterogeneous group of glucose polymers with a common structure comprising a main chain of beta-(1,3) and/or beta-(1,4)-glucopyranosyl units, along with side chains with various branches and lengths. beta-Glucans initiate immune responses via immune cells, which become activated by the binding of the polymer to specific receptors. However, beta-glucans from different sources also differ in their structure, conformation, physical properties, binding affinity to receptors, and thus biological functions. The mechanisms behind this are not fully understood. This mini-review provides a comprehensive and up-to-date commentary on the relationship between beta-glucans' structure and function in relation to their use for immunomodulation.
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- Binder, Christian, et al.
(author)
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CD2 Immunobiology
- 2020
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In: Frontiers in Immunology. - : Frontiers Media SA. - 1664-3224. ; 11
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Research review (peer-reviewed)abstract
- The glycoprotein CD2 is a costimulatory receptor expressed mainly on T and NK cells that binds to LFA3, a cell surface protein expressed on e.g., antigen-presenting cells. CD2 has an important role in the formation and organization of the immunological synapse that is formed between T cells and antigen-presenting cells upon cell-cell conjugation and associated intracellular signaling. CD2 expression is upregulated on memory T cells as well as activated T cells and plays an important role in activation of memory T cells despite the coexistence of several other costimulatory pathways. Anti-CD2 monoclonal antibodies have been shown to induce immune modulatory effectsin vitroand clinical studies have proven the safety and efficacy of CD2-targeting biologics. Investigators have highlighted that the lack of attention to the CD2/LFA3 costimulatory pathway is amissed opportunity. Overall, CD2 is an attractive target for monoclonal antibodies intended for treatment of pathologies characterized by undesired T cell activation and offers an avenue to more selectively target memory T cells while favoring immune regulation.
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