Regulation of cellular and humoral immune responses to collagen type I or collagen type II.

We have investigated the characteristics of antigen-specific reductions in murine immune responses to rat collagen type I (R-CI), chick collagen type II (C-CII) or bovine collagen type II (B-CII). Intravenous pretreatment with the appropriate soluble collagen or collagen-coupled spleen cells led to the development of antigen-specific reduced immune responses, the former treatment being more effective than the latter. In the case of CII, pretreatment with R-CI or non-related antigens was ineffective. However, pretreatment with denatured bovine-CII, native bovine-CII or chick-CII led to immune hyporesponsiveness for either the homologous or heterologous CII molecule. A delayed development of the diminished immune responses was observed for the cell-mediated immune response (CMI), as measured by in vivo delayed-type hypersensitivity (DTH), in that no reduction was evident at Day 7 but a significantly decreased response was observed at Day 14. Collagen-specific IgG and IgM antibody responses were consistently reduced by the pretreatment and remained reduced during the study period. The antigen-specific hyporesponsive state was not sensitive to cyclophosphamide treatment and was not transferable with hyporesponsive spleen cells. Additionally, we have induced unresponsiveness to CII by treating mice with an antibody directed to T helper cells (GK1.5). This treatment led to profound reductions in CII CMI responses as well as CII antibody levels. However, this unresponsive state is not permanent and not transferable with spleen cells from treated mice. These two types of procedures, soluble B-CII i.v. or GK1.5 treatment, not only resulted in CII hyporesponsive states, but also produced delayed onset and decreased incidence of arthritis in the appropriate strains.     

Viruses and the type I interferon antiviral system: induction and evasion

The type I interferon (IFN) system responds to viral infection and induces an "antiviral state" in cells, providing an important first line of defense against virus infection. Interaction of type I IFNs (IFN alpha and IFN beta) with their receptor induces hundreds of cellular genes. Of the proteins induced by IFN, the antiviral function of only a few is known, and their mechanisms of action are only partly understood. Additionally, although viral-encoded mechanisms that counteract specific components of the type I IFN response have been known for some time, it has recently become clear that many (if not most) viruses encode some form of IFN-antagonist. Understanding the interplay between viral-encoded IFN antagonists and the interferon response will be essential if the therapeutic potential of IFNs is to be fully exploited.     

Induction and evasion of type I interferon responses by influenza viruses

Influenza A and B viruses are a major cause of respiratory disease in humans. In addition, influenza A viruses continuously re-emerge from animal reservoirs into humans causing human pandemics every 10-50 years of unpredictable severity. Among the first lines of defense against influenza virus infection, the type I interferon (IFN) response plays a major role. In the last 10 years, there have been major advances in understanding how cells recognize being infected by influenza viruses, leading to secretion of type I IFN, and on the effector mechanisms by how IFN exerts its antiviral activity. In addition, we also now know that influenza virus uses multiple mechanisms to attenuate the type I IFN response, allowing for successful infection of their hosts. This review highlights some of these findings and illustrates future research avenues that might lead to new vaccines and antivirals based on the further understanding of the mechanisms of induction and evasion of type I IFN responses by influenza viruses.     

Immunosuppressive effects of lymphocyte (type II) and leucocyte (type I) interferon on primary antibody responses in vivo and in vitro.

We have tested the hypothesis that type II interferon (IF), released by immune lymphocytes after in vivo stimulation with tuberculin, has immunosuppressive effects. Mycobacterium bovis (BCG) infected mice injected with tuberculin showed a very intense suppression of antibody response to sheep erythrocytes. Sera containing lymphocyte IF strongly inhibited primary immune responses to sheep erythrocytes in cultures. Addition of macrophages could not counteract the in vitro immunosuppressive effects of lymphocyte IF, suggesting that the main effect is exerted directly on lymphocytes. Sendai virus-induced leucocyte (type I) IF was also shown to have suppressive effects in vivo and in vitro. However, lymphocyte IF was shown to be much more immunosuppressive than a preparation of type I interferon with equivalent antiviral potency. Thus type II IF, as a product of activated lymphocytes, may have a major immunoregulatory role.     

Leveraging the antiviral type I interferon system as a first line of defense against SARS-CoV-2 pathogenicity

1. Download : Download high-res image (200KB)
2. Download : Download full-size image

     

Modulation of immune responses in newborn and adult mice by interferon.

Interferon was found to have both suppressive and enhancing effects on the antibody response in newborn and adult mice. Evidence was obtained that these effects are primarily evoked during the initial steps controlling cell proliferation. Stimulation of thymus and spleen cells with a T-cell mitogen was enhanced by low doses and suppressed by high doses of interferon. Treatment of parental spleen cells with interferon before injecting them into immunized F1 hybrid mice resulted in an enhanced allogeneic effect. These results are compatible with the hypothesis that interferon affects T cells and has an immunoregulatory role, either by inhibiting the action of suppressor cells or by promoting immunological maturation.     

Mechanism of interferon action. Expression of reovirus S3 gene in transfected COS cells and subsequent inhibition at the level of protein synthesis by type I but not by type II interferon

The effect of interferon on the expression of the reovirus serotype 1 Lang strain S3 gene was examined in simian COS cells transfected with the expression vector pSVS3 containing the S3 gene under the control of the SV40 late promoter. When COS cells were treated with type I interferon-alpha 24 hr after transfection, the synthesis of the reovirus S3-encoded sigma NS polypeptide was inhibited about 10-fold as compared to that in untreated control cells. By contrast, under the same conditions, neither the plasmid DNA copy number nor the S3 gene mRNA levels were significantly affected by interferon treatment. Type II interferon-gamma, unlike the type I interferons-alpha, did not affect the rate of synthesis of polypeptide sigma NS in pSVS3-transfected cells.     

MxA-independent inhibition of Hantaan virus replication induced by type I and type II interferon in vitro

Interferons (IFN) induce an antiviral state against Hantaan virus (HTNV) but the mechanisms responsible for inhibition are unclear. The IFN-inducible MxA is discussed to be important for control of infections with hantaviruses. To characterize the role of endogenous MxA, the inhibition of HTNV induced by type I and type II IFNs was compared in Vero and A549 cells. IFNalpha and IFNgamma reduced production of infectious virions, viral RNA, and nucleocapsid protein with the same efficiency, although expression of MxA protein was detectable only in IFNalpha-treated A549 cells. Furthermore, knock down of MxA expression did not impair IFNalpha-induced inhibition. Thus, inhibition of HTNV induced by type I and type II IFNs did not dependent on expression of endogenous MxA. Taken together, these data suggest that MxA endogenously expressed in response to type I or type II IFNs does not play a pivotal role for the antiviral state against HTNV and that there is more than one mechanism by which cellular defences block hantavirus replication.     

Critical role of the endogenous interferon ligand–receptors in type I and type II interferons response

Separate ligand–receptor paradigms are commonly used for each type of interferon (IFN). However, accumulating evidence suggests that type I and type II IFNs may not be restricted to independent pathways. Using different cell types deficient in IFNAR1, IFNAR2, IFNGR1, IFNGR2 and IFN‐γ, we evaluated the contribution of each element of the IFN system to the activity of type I and type II IFNs. We show that deficiency in IFNAR1 or IFNAR2 is associated with impairment of type II IFN activity. This impairment, presumably resulting from the disruption of the ligand–receptor complex, is obtained in all cell types tested. However, deficiency of IFNGR1, IFNGR2 or IFN‐γ was associated with an impairment of type I IFN activity in spleen cells only, correlating with the constitutive expression of type II IFN (IFN‐γ) observed on those cells. Therefore, in vitro the constitutive expression of both the receptors and the ligands of type I or type II IFN is critical for the enhancement of the IFN activity. Any IFN deficiency can totally or partially impair IFN activity, suggesting the importance of type I and type II IFN interactions. Taken together, our results suggest that type I and type II IFNs may regulate biological activities through distinct as well as common IFN receptor complexes.     

Plasmacytoid dendritic cells act as the most competent cell type in linking antiviral innate and adaptive immune responses

Appropriate in vivo control of plasmacytoid dendritic cell （pDC） recruitment and activation is a fundamental requirement for defense against viral infection. During this process, a pivotal event that influences the outcome of viral infection is the production of high levels of type I interferon by pDCs. In particular, recent research findings showed that pDCs not only shape the nature of innate resistance, but are also responsible for the successful transition from innate to adaptive immunity for viral resistance. In addition, pDCs can differentiate into antigen presenting cells that may regulate tolerance to a given pathogen. Importantly, in a series of recent clinical studies, pDCs appeared to be defective in number and function in conditions of chronic viral diseases such as infected with HIV-1, HBV or HCV. pDC-associated clinical antiviral therapy is also emerging. This review describes research findings exatnining the functional and antiviral properties of in vivo pDC plasticity. Cellular ＆ Molecular Immunology. 2005;2（6）：411- 417.     

Impaired immune responses in streptozotocin-induced type I diabetes in mice. Involvement of high glucose

Diabetes is widely believed to predispose to serious infections. However, the mechanisms linking diabetes and immunosuppression are not well defined. One potential mediator of the altered defence mechanisms is hyperglycaemia. It has been identified as the main factor contributing to the development of diseases associated with diabetes mellitus. In this study we analyse the immune response in diabetes and the direct effect of hyperglycaemia on T and B lymphocyte reactivity. Diabetes induced an early decrease in IgG levels in the secondary response. However, both primary responses against a T-cell-dependent or independent antigen were affected after 6 months of diabetes induction. T- and B- cell proliferation was only decreased at this time. To gain insight into the potential mechanisms involved, we evaluated the influence of hyperglycaemia over the immune response. Pre-incubation of lymph node and spleen cells in a high glucose (HG) containing medium led to a significant time- and dose-dependent decrease in T- and B-cell proliferation. This effect was associated with the presence of HG-derived supernatants. Still viable cells after HG exposition were able to improve their proliferative response when cultured with the mitogen in a fresh standard medium. HG diminished cell viability, increased apoptosis and induced oxidative stress in lymphocytes. These results indicate that HG concentrations can directly affect lymphoid cell growth. An increase in oxidative stress would be implicated in this deleterious effect. The possibility that prolonged exposure to pathologically HG concentrations would result in the immunosuppressive state observed in diabetes is also discussed.     

Characterization of type I interferon responses in dengue and severe dengue in children in Paraguay

BackgroundInfection with dengue virus (DENV) produces a wide spectrum of clinical illness ranging from asymptomatic infection to mild febrile illness, and to severe forms of the disease. Type I interferons (IFNs) represent an initial and essential host defense response against viruses. DENV has been reported to trigger a robust type I IFN response; however, IFN-α/β profile in the progression of disease is not well characterized.Objectives and study designIn this context, we conducted a retrospective study assessing the circulating serum levels of type I IFNs and related cytokines at different phases of illness in children during the 2011 outbreak of DENV in Paraguay. Demographic, clinical, laboratory and virological data were analyzed.ResultsDuring defervescence, significantly higher levels of IFN-β, IL-6 and MIP-1β, were detected in severe vs. non-severe dengue patients. Additionally, a significant positive correlation between INF-α and viremia was detected in children with severe dengue. A significant positive correlation was also observed between IFN-β serum levels and hematocrit during the febrile phase, whereas IFN-α levels negatively correlated with white blood cells during defervescence in severe dengue patients. Furthermore, previous serologic status of patients to DENV did not influence type I IFN production.ConclusionsThe distinct type I IFN profile in children with dengue and severe dengue, as well as its association with viral load, cytokine production and laboratory manifestations indicate differences in innate and adaptive immune responses that should be investigated further in order to unveil the association of immunological and physiological pathways that underlie in DENV infection.     

Daily intake of heat-killed Lactobacillus plantarum L-137 enhances type I interferon production in healthy humans and pigs

We have previously reported that oral administration of heat-killed Lactobacillus plantarum L-137 (HK L-137) stimulates innate immunity for production of type I interferon (IFN) which subsequently augments host defense against influenza A virus infection in mice. We here examined the effect of HK L-137 intake on type I IFN in humans. Sixteen subjects were randomly assigned to receive a tablet containing 10?mg of HK L-137 or a matching tablet for 8 weeks and the serum levels of type I IFN were examined before and after the first or second dose of the trivalent inactivated influenza vaccine. There were no differences in the seroresponse rate, the seroprotection rate and the geometric mean Ab titers after either the first or second dose of vaccine between the HK L-137 group and the control group. On the other hand, the levels of IFN-β were significantly higher in the HK L-137 group than in the control group before vaccination although the vaccination conferred little additional induction of IFN-β. We further examined IFN-β gene expression in the whole blood cells of pigs fed on a diet containing HK L-137 and found that the IFN-β mRNA levels were significantly higher in the HK L-137 group than in the control group. The finding that daily intake of HK L-137 enhances type I IFN production and host defense against influenza A virus infection in mice may be applied to at least two additional species.     

In vitro production and cellular origin of murine type II interferon.

Antigen-specific type II interferon was produced in vitro by harvesting supernatants of spleen cell cultures from Swiss-Webster mice sensitized with Mycobacterium bovis strain BCG and challenged with old tuberculin. Treatment of C3H mouse spleen cell cultures with appropriate anti-Ia, anti-IgG, anti-Thy-1 or anti-Ly-2,3 sera resulted in a significant decrease in production of type II interferon. Removal of nylon wool adherent cells or cells with histamine receptors by column chromatography similarly caused reduced production of type II interferon. Recombination of spleen cell cultures treated with anti-Ia and anti-Thy-1 sera or of cells treated with anti-IgG and anti-Thy-1 resulted in restored production of type II interferon. Interferon production was also restored by combination of cells passed through histamine columns with anti-Ia treated cells, or those passed through nylon wool columns with anti-Thy-1 treated cells. Anti-Ly-1 serum treatment had no effect on interferon production. Removal of plastic-adherent cells or cells that had phagocytosed carbonyl iron also decreased interferon production, suggesting that macrophages were also involved in type II interferon production. Recombination of non-adherent spleen cells with anti-Ia and anti-Thy-1 sera treated spleen cells, however, did not restore interferon production, suggesting that other cells in addition to macrophages are depleted by the adherence procedure. These findings indicate that type II interferon is produced by suppressor or cytotoxic (Ly-2,3+) T lymphocytes in co-operation with one or two additional cell types: (i) B lymphocytes, and (ii) macrophages.     

Trial of sulfonylurea in combination with insulin in the therapy of diabetes type I and II

Summary Recently in vitro evidence has been presented that sulfonylurea derivatives exert their chronic extrapancreatic effect by increasing the number of cellular insulin receptors. To ascertain if this receptor effect holds in vivo, we performed a randomized double-blind study on 21 type I (0.3 ng/ml residual C-peptide secretory capacity after glucose/glibenclamide stimulation), and on 19 insulin treated type II (2.0 ng/ml C-peptide) diabetics. The patients received for six weeks 10 mg/d of glibenclamide in addition to insulin. Insulin binding was initially lower in type II (4.7±0.75% per 10⁷ monocytes and 6.39±1.08% per 4.5×10⁹ erythrocytes) than in type I diabetic patients (5.1±0.48% and 7.95±0.88% respectively) and in 12 normal subjects (5.25±0.48 and 8.1±0.94% respectively). Glibenclamide normalized the number of monocyte receptors (from 4.14 to 5.49×10⁴ sites/cell) in type II patients, but was without effect in type I diabetics. Blood glucose was significantly reduced (240 to 182 mg/dl;p=0.02) in the type II group with a concomitant decrease in glycosylated hemoglobin from 12.4 to 10.5% (p=0.01). Most of the effect occured during the first week of treatment. Glibenclamide was the more effective the worse the initial metabolic state (r=–0.93;p=0.001). Erythrocyte insulin receptors decreased markedly in both groups, perhaps due to a sulfonyl urea-induced change in erythrocyte plasma survival time. It is concluded that sulfonylurea treatment is a valuable adjunct in reducing the insulin resistance in insulin treated type II diabetics. The effect depends on the availability of endogenous insulin, thus exhibiting only partly extrapancreatic character. The receptor effect in the type II patients may be secondary to the metabolic improvement.Supported by the Deutsche Forschungsgemeinschaft (DFG Bi 236/3-2)     

Revision of the functional analysis and structural features of immortalized dendritic cell lines derived from mice lacking both type I and type II interferon receptors.

Cell lines with dendritic morphology were obtained from several organs of mice lacking both type I and II interferon receptors after a retroviral immortalization procedure. Their surface antigen phenotype was analyzed by flow cytometry with monoclonal antibodies and their functional capabilities to induce antigen dependent specific immune response was also determined. Two representative cell lines called AG101 (skin-derived) and AG116 (brain-derived) were cloned and analyzed in more detail. Cytometric analysis showed that they constitutively expressed the cell surface markers CD45, CD1 1b, MHC class II, F4/80, N418, B7-2 and ICAM1. Despite both cell lines expressing Thy-1 only, the AG116 show CD4 but both were negative for CD8 and B220. The functional analysis showed that the cell lines were capable and very efficient at actively taking up, processing and presenting soluble antigens like Ovalbumin (OVA). The processed protein was presented by both cell lines to the OVA-peptide-specific T cell hybridoma BO97.105, which responded specifically with the production of IL-2. In addition AG101 and AG116 cells were able to induce in naive allogeneic T cells, a mixed lymphocyte reaction, determined by T cell proliferation and T cell dependent L-2 production. Moreover, the capability to prime naive syngeneic T cells was also demonstrated by loading AG101 and AG116 cells with soluble antigens, then co-culturing with naive T cells which yielded both T cell proliferation and IL-2 production. The cell lines priming capability was shown to be quite similar, as freshly isolated and cultured cutaneous dendritic cells from 129Sv/Lv mice (wtDCs) to prime naive T cells. In addition to a basal production of IL-6, the cell lines were found to increase their synthesis of IL-6 and IL-12 p40 after interaction with T cells in a similar way as mature wtDCs. Also it was determined that DC cell lines devoid of functional IFN system allow the replication of infectious agents like BDV and even are able to induce in vivo a specific humoral response against proteins of the BDV. Therefore, the cell lines AG101 and AG116 show structural and functional features of DCs. They are able to take up, process and present antigens as well as prime naive T cell in a similar manner as nontransformed DC. Therefore, these cell lines will be useful for studying the interactions between DC and the effectors cells of the immune response at the clonal level and in the absence of functional interferon receptors.