The major protective immune response against viruses is the production of type I and III interferons (IFNs). IFNs induce the expression of hundreds of IFN-stimulated genes (ISGs) that block viral replication and further viral spread. In this report, we analyzed the expression of IFNs and some ISGs (MxA, PKR, OAS-1, IFIT-1, RIG-1, MDA5, SOCS-1) in alveolar epithelial cells (A549) in response to infection with influenza A viruses (A/California/07/09 (H1N1pdm); A/Texas/50/12 (H3N2)); influenza B virus (B/Phuket/3073/13); adenovirus type 5 and 6; or respiratory syncytial virus (strain A2). Influenza B virus had the ability to most rapidly induce IFNs and ISGs as well as to stimulate excessive IFN-α, IFN-β and IFN-λ secretion. It seems curious that IAV H1N1pdm did not induce IFN-λ secretion, but enhanced type I IFN and interleukin (IL)-6 production. We emphasized the importance of the negative regulation of virus-triggered signaling and cellular IFN response. We showed a decrease in IFNLR1 mRNA in the case of IBV infection. The attenuation of SOCS-1 expression in IAV H1N1pdm can be considered as the inability of the system to restore the immune status. Presumably, the lack of negative feedback loop regulation of proinflammatory immune response may be a factor contributing to the particular pathogenicity of several strains of influenza. Keywords: lambda interferons; MxA; influenza; respiratory syncytial virus; A549 cells.

The major protective immune response against viruses is production of type I and III interferons (IFNs). IFNs induce the expression of hundreds of IFN-stimulated genes (ISGs) that block viral replication and further viral spread. The ability of respiratory viruses to suppress induction of IFN-mediated antiviral defenses in infected epithelial cells may be a factor contributing to the particular pathogenicity of several strains. In this report, we analyzed expression of IFNs and some ISGs in an alveolar epithelial cell subtype (A549) in response to infection with: influenza A viruses (A/California/07/09pdm (H1N1), A/Texas/50/12 (H3N2)); influenza B virus (B/Phuket/3073/13); adenovirus type 5 and 6; or respiratory syncytial virus (strain A2). IFNL and ISGs expression significantly increased in response to infection with all RNA viruses 24 hpi. Nevertheless, only IBV led to early increase in IFNL and ISGs mRNA level. IBV and H1N1 infection led to elevated proinflammatory cytokine production. We speculate that augmented IFN-α, IFN-β, IL-6 levels negatively correlate to SOCS1 expression. Importantly, we showed a decrease in IFNLR1 mRNA in case of IBV infection that implies the existence of negative ISGs expression regulation at IFNλR level. It could be either a specific feature of IBV or a consequence of early IFNL expression.

One of the main functions of alpha-2-macroglobulin (A2M) in human blood serum is the binding of all classes of protease. It is known that trypsin, after such interaction, possesses modified proteolytic activity. Trypsin first hydrolyzes two bonds in A2M's 'bait region', and the peptide 705VGFYESDVMGR715 is released from A2M. In this work, specifics of the A2M-trypsin interaction were used to determine A2M concentration directly in human blood serum using MALDI mass-spectrometry. Following exogenous addition of trypsin to human blood serum in vitro, the concentration of the VGFYESDVMGR peptide was measured, using its isotopically-labeled analogue (18O), and A2M concentration was calculated. The optimized mass spectrometric approach was verified using a standard method for A2M concentration determination (ELISA) and the relevant statistical analysis methods. It was also shown that trypsin's modified proteolytic activity in the presence of serum A2M can be used to analyze other serum proteins, including potential biomarkers of pathological processes. Thus, this work describes a promising approach to serum biomarker analysis that can be technically extended in several useful directions.
Copyright © 2021 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.

The DRB1*15:01-DQB1*06:02 (DR1501-DQ6) haplotype is linked to dominant protection from type 1 diabetes, but the cellular mechanism for this association is unclear. To address this question, we identified multiple DR1501- and DQ6-restricted glutamate decarboxylase 65 (GAD65) and islet-specific glucose-6-phosphatase catalytic subunit-related protein (IGRP)-specific T cell epitopes. Three of the DR1501/DQ6-restricted epitopes identified were previously reported to be restricted by DRB1*04:01/DRB1*03:01/DQB1*03:02. We also used specific class II tetramer reagents to assess T cell frequencies. Our results indicated that GAD65- and IGRP-specific effector and CD25+CD127-FOXP3+ regulatory CD4+ T cells were present at higher frequencies in individuals with the protective haplotype than those with susceptible or neutral haplotypes. We further confirmed higher frequencies of islet antigen-specific effector and regulatory CD4+ T cells in DR1501-DQ6 individuals through a CD154/CD137 up-regulation assay. DR1501-restricted effector T cells were capable of producing interferon-γ (IFN-γ) and interleukin-4 (IL-4) but were more likely to produce IL-10 compared with effectors from individuals with susceptible haplotypes. To evaluate their capacity for antigen-specific regulatory activity, we cloned GAD65 and IGRP epitope-specific regulatory T cells. We showed that these regulatory T cells suppressed DR1501-restricted GAD65- and IGRP-specific effectors and DQB1*03:02-restricted GAD65-specific effectors in an antigen-specific fashion. In total, these results suggest that the protective DR1501-DQ6 haplotype confers protection through increased frequencies of islet-specific IL-10-producing T effectors and CD25+CD127-FOXP3+ regulatory T cells.
Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

IFN-γ-producing T helper 1 (Th1) cell responses mediate protection against infections but uncontrolled Th1 activity also contributes to a broad range of autoimmune diseases. Autocrine complement activation has recently emerged as key in the induction and contraction of human Th1 immunity: activation of the complement regulator CD46 and the C3aR expressed by CD4+ T cells via autocrine generated ligands C3b and C3a, respectively, are critical to IFN-γ production. Further, CD46-mediated signals also induce co-expression of immunosuppressive IL-10 in Th1 cells and transition into a (self)-regulating and contracting phase. In consequence, C3 or CD46-deficient patients suffer from recurrent infections while dysregulation of CD46 signaling contributes to Th1 hyperactivity in rheumatoid arthritis and multiple sclerosis. Here, we report a defect in CD46-regulated Th1 contraction in patients with systemic lupus erythematosus (SLE). We observed that MMP-9-mediated increased shedding of soluble CD46 by Th1 cells was associated with this defect and that inhibition of MMP-9 activity normalized release of soluble CD46 and restored Th1 contraction in patients' T cells. These data may deliver the first mechanistic explanation for the increased serum CD46 levels observed in SLE patients and indicate that targeting CD46-cleaving proteases could be a novel avenue to modulate Th1 responses.
© 2017 The Authors. European Journal of Immunology published by WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.