IL-2 suppression of IL-12p70 by a recombinant HSV-1 expressing IL-2 induces T-cell auto-reactivity and CNS demyelination.
ABSTRACT: To evaluate the role of cellular infiltrates in CNS demyelination in immunocompetent mice, we have used a model of multiple sclerosis (MS) in which different strains of mice are infected with a recombinant HSV-1 expressing IL-2. Histologic examination of the mice infected with HSV-IL-2 demonstrates that natural killer cells, dendritic cells, B cells, and CD25 (IL-2r?) do not play any role in the HSV-IL-2-induced demyelination. T cell depletion, T cell knockout and T cell adoptive transfer experiments suggest that both CD8(+) and CD4(+) T cells contribute to HSV-IL-2-induced CNS demyelination with CD8(+) T cells being the primary inducers. In the adoptive transfer studies, all of the transferred T cells irrespective of their CD25 status at the time of transfer were positive for expression of FoxP3 and depletion of FoxP3 blocked CNS demyelination by HSV-IL-2. The expression levels of IL-12p35 relative to IL-12p40 differed in BM-derived macrophages infected with HSV-IL-2 from those infected with wild-type HSV-1. HSV-IL-2-induced demyelination was blocked by injecting HSV-IL-2-infected mice with IL-12p70 DNA. This study demonstrates that suppression of the IL-12p70 function of macrophages by IL-2 causes T cells to become auto-aggressive. Interruption of this immunoregulatory axis results in demyelination of the optic nerve, the spinal cord and the brain by autoreactive T cells in the HSV-IL-2 mouse model of MS.
Project description:Summary We previously reported that infection of different mouse strains with a recombinant HSV-1 expressing IL-2 (HSV-IL-2) caused CNS demyelination. Histologic examination of infected IL-2r??/?, IL-2r??/?, and IL-2r??/? mice showed demyelination in the CNS of IL-2r??/? and IL-2r??/? mice but not in the CNS of IL-2r??/?-infected mice. No demyelination was detected in mice infected with control virus. IL-2r??/? mice that lack type 2 innate lymphoid cells (ILC2s) and ILCs, play important roles in host defense and inflammation. We next infected ILC1?/?, ILC2?/?, and ILC3?/? mice with HSV-IL-2 or wild-type (WT) HSV-1. In contrast to ILC1?/? and ILC3?/? mice, no demyelination was detected in the CNS of ILC2?/?-sinfected mice. However, transfer of ILC2s from WT mice to ILC2?/? mice restored demyelination in infected recipient mice. CNS demyelination correlated with downregulation of CCL5 and CXCL10. This study demonstrates that ILC2s contribute to HSV-IL-2-induced CNS demyelination in a mouse model of multiple sclerosis. Graphical Abstract Highlights • IL-2r??/?, but not IL-2r??/? or IL-2r??/?, mice are protected from CNS demyelination• Mice lacking ILC2s, but not ILC1s or ILC3s, are protected from CNS demyelination• Transfer of ILC2s from WT to ILC2?/? mice restore CNS demyelination to infected mice• Suppression of CCL5 and CXCL10 correlated with CNS demyelination Immunology; Neuroscience
Project description:The interleukin (IL)-12p40 family of cytokines plays a critical role in the development of experimental autoimmune encephalomyelitis (EAE). However, the relative contributions of IL-12 and IL-23 to the pathogenic process remain to be elucidated. Here, we show that activation of uncommitted myelin-reactive T cells in the presence of either IL-12p70 or IL-23 confers encephalogenicity. Adoptive transfer of either IL-12p70- or IL-23-polarized T cells into naive syngeneic hosts resulted in an ascending paralysis that was clinically indistinguishable between the two groups. However, histological and reverse transcription-polymerase chain reaction analysis of central nervous system (CNS) tissues revealed distinct histopathological features and immune profiles. IL-12p70-driven disease was characterized by macrophage-rich infiltrates and prominent NOS2 up-regulation, whereas neutrophils and granulocyte-colony-stimulating factor (CSF) were prominent in IL-23-driven lesions. The monocyte-attracting chemokines CXCL9, 10, and 11 were preferentially expressed in the CNS of mice injected with IL-12p70-modulated T cells, whereas the neutrophil-attracting chemokines CXCL1 and CXCL2 were up-regulated in the CNS of mice given IL-23-modulated T cells. Treatment with anti-IL-17 or anti-granulocyte/macrophage-CSF inhibited EAE induced by transfer of IL-23-polarized, but not IL-12p70-polarized, cells. These findings indicate that autoimmunity can be mediated by distinct effector populations that use disparate immunological pathways to achieve a similar clinical outcome.
Project description:Immune-mediated diseases of the CNS, such as multiple sclerosis and its animal model, experimental autoimmune encephalitis (EAE), are characterized by the activation of antigen-presenting cells and the infiltration of autoreactive lymphocytes within the CNS, leading to demyelination, axonal damage, and neurological deficits. Hepatocyte growth factor (HGF) is a pleiotropic factor known for both neuronal and oligodendrocytic protective properties. Here, we assess the effect of a selective overexpression of HGF by neurons in the CNS of C57BL/6 mice carrying an HGF transgene (HGF-Tg mice). EAE induced either by immunization with myelin oligodendrocyte glycoprotein peptide or by adoptive transfer of T cells was inhibited in HGF-Tg mice. Notably, the level of inflammatory cells infiltrating the CNS decreased, except for CD25(+)Foxp3(+) regulatory T (T(reg)) cells, which increased. A strong T-helper cell type 2 cytokine bias was observed: IFN-gamma and IL-12p70 decreased in the spinal cord of HGF-Tg mice, whereas IL-4 and IL-10 increased. Antigen-specific response assays showed that HGF is a potent immunomodulatory factor that inhibits dendritic cell (DC) function along with differentiation of IL-10-producing T(reg) cells, a decrease in IL-17-producing T cells, and down-regulation of surface markers of T-cell activation. These effects were reversed fully when DC were pretreated with anti-cMet (HGF receptor) antibodies. Our results suggest that, by combining both potentially neuroprotective and immunomodulatory effects, HGF is a promising candidate for the development of new treatments for immune-mediated demyelinating diseases associated with neurodegeneration such as multiple sclerosis.
Project description:Several mouse models of multiple sclerosis (MS) are now available. We have established a mouse model, in which ocular infection with a recombinant HSV-1 that expresses murine interleukin (IL)-2 constitutively (HSV-IL-2) causes central nervous system demyelination in different strains of mice. This model differs from most other models, in which it represents a mixture of viral and immune triggers. In the present study, we directly compared MOG35-55, MBP35-47 and PLP190-209 models of experimental autoimmune encephalitis with our HSV-IL-2-induced MS model. Mice with HSV-IL-2- and myelin oligodendrocyte glycoprotein (MOG)-induced demyelinating diseases demonstrated a similar pattern and distribution of demyelination in their brain, spinal cord (SC) and optic nerves (ONs). In contrast, no demyelination was detected in the ONs of myelin basic protein (MBP)- and proteolipid protein (PLP)-injected mice. Interferon-? (IFN-?) injections significantly reduced demyelination in brains of all groups, in the SCs of the MOG and MBP groups, and completely blocked it in the SCs of the PLP and HSV-IL-2 groups as well as in ONs of MOG and HSV-IL-2 groups. In contrast to IFN-? treatment, IL-12p70 protected the HSV-IL-2 group from demyelination, whereas IL-4 was not effective at all in preventing demyelination. MOG-injected mice showed clinical signs of paralysis and disease-related mortality, whereas mice in the other treatment groups did not. Collectively, the results indicate that the HSV-IL-2 model and the MOG model complement each other and, together, provide unique insights into the heterogeneity of human MS.
Project description:Natural killer (NK) cells are effector lymphocytes that are under clinical investigation for the adoptive immunotherapy of hematologic malignancies, especially acute myeloid leukemia. Recent work in mice has identified innate memory-like properties of NK cells. Human NK cells also exhibit memory-like properties, and cytokine-induced memory-like (CIML) NK cells are generated via brief preactivation with IL-12, IL-15, and IL-18, which later exhibit enhanced functionality upon restimulation. However, the optimal cytokine receptors and signals for maintenance of enhanced function and homeostasis after preactivation remain unclear. Here, we show that IL-12, IL-15, and IL-18 preactivation induces a rapid and prolonged expression of CD25, resulting in a functional high-affinity IL-2 receptor (IL-2R???) that confers responsiveness to picomolar concentrations of IL-2. The expression of CD25 correlated with STAT5 phosphorylation in response to picomolar concentrations of IL-2, indicating the presence of a signal-competent IL-2R???. Furthermore, picomolar concentrations of IL-2 acted synergistically with IL-12 to costimulate IFN-? production by preactivated NK cells, an effect that was CD25 dependent. Picomolar concentrations of IL-2 also enhanced NK cell proliferation and cytotoxicity via the IL-2R???. Further, after adoptive transfer into immunodeficient NOD-SCID-?c(-/-) mice, human cytokine-preactivated NK cells expand preferentially in response to exogenous IL-2. Collectively, these data demonstrate that human CIML NK cells respond to IL-2 via IL-2R??? with enhanced survival and functionality, and they provide additional rationale for immunotherapeutic strategies that include brief cytokine preactivation before adoptive NK cell transfer, followed by low-dose IL-2 therapy.
Project description:HSV-1 is the leading cause of sporadic encephalitis in humans. HSV infection of susceptible 129S6 mice results in fatal encephalitis (HSE) caused by massive inflammatory brainstem lesions comprising monocytes and neutrophils. During infection with pathogenic microorganisms or autoimmune disease, IgGs induce proinflammatory responses and recruit innate effector cells. In contrast, high dose intravenous immunoglobulins (IVIG) are an effective treatment for various autoimmune and inflammatory diseases because of potent anti-inflammatory effects stemming in part from sialylated IgGs (sIgG) present at 1-3% in IVIG. We investigated the ability of IVIG to prevent fatal HSE when given 24 h post infection. We discovered a novel anti-inflammatory pathway mediated by low-dose IVIG that protected 129S6 mice from fatal HSE by modulating CNS inflammation independently of HSV specific antibodies or sIgG. IVIG suppressed CNS infiltration by pathogenic CD11b(+) Ly6C(high) monocytes and inhibited their spontaneous degranulation in vitro. Fc?RIIb expression was required for IVIG mediated suppression of CNS infiltration by CD45(+) Ly6C(low) monocytes but not for inhibiting development of Ly6C(high) monocytes. IVIG increased accumulation of T cells in the CNS, and the non-sIgG fraction induced a dramatic expansion of FoxP3(+) CD4(+) T regulatory cells (Tregs) and FoxP3(-) ICOS(+) CD4(+) T cells in peripheral lymphoid organs. Tregs purified from HSV infected IVIG treated, but not control, mice protected adoptively transferred mice from fatal HSE. IL-10, produced by the ICOS(+) CD4(+) T cells that accumulated in the CNS of IVIG treated, but not control mice, was essential for induction of protective anti-inflammatory responses. Our results significantly enhance understanding of IVIG's anti-inflammatory and immunomodulatory capabilities by revealing a novel sIgG independent anti-inflammatory pathway responsible for induction of regulatory T cells that secrete the immunosuppressive cytokine IL-10 and further reveal the therapeutic potential of IVIG for treating viral induced inflammatory diseases.
Project description:IL-27 counters the effect of TGF-beta+IL-6 on naive CD4(+) T cells, resulting in near complete inhibition of de novo Th17 development. In contrast, little is known about the effect of IL-27 on already differentiated Th17 cells. A better understanding of how IL-27 regulates these cells is needed to evaluate the therapeutic potential of IL-27 in Th17 cells-associated diseases. In this study, we show that IL-27 had surprisingly little effect on committed Th17 cells, despite its expression of a functional IL-27R. Contrary to de novo differentiation of Th17 cells, IL-27 did not suppress expression of retinoid-related orphan receptor (ROR)gammat or RORalpha in committed Th17 cells. Consistent with this finding, the frequency of committed Th17 cells and their cytokine secretion remained unaffected by IL-27. Both memory Th17 cells (CD4(+)CD25(-)CD62L(low)) that developed in vivo and encephalitogenic Th17 cells infiltrating the CNS of mice developing experimental autoimmune encephalomyelitis produced similar amounts of IL-17A when reactivated with IL-23 in the absence and presence of exogenous IL-27. Finally, IL-27 failed to suppress encephalitogenicity of Th17 cells in an adoptive transfer of experimental autoimmune encephalomyelitis. Analysis ex vivo of transferred Th17 cells in the spleen and CNS of recipient mice showed that cells retained similar phenotype irrespective of whether cells were treated or not with IL-27. Our data demonstrate that in contrast to inhibition of de novo differentiation of Th17 cells, IL-27 has little or no effect on committed Th17 cells. These findings indicate that therapeutic applications of IL-27 might have a limited efficacy in inflammatory conditions where aggressive Th17 responses have already developed.
Project description:Bacterial vectors have been proposed as novel vaccine strategies to induce strong cellular immunity. Attenuated strains of Brucella abortus comprise promising vector candidates since they have the potential to induce strong CD4(+) and CD8(+) T-cell mediated immune responses in the absence of excessive inflammation as observed with other Gram-negative bacteria. However, some Brucella strains interfere with the maturation of dendritic cells (DCs), which is essential for antigen-specific T-cell priming. In the present study, we investigated the interaction of human monocyte-derived DCs with the smooth attenuated B. abortus strain (S) 19, which has previously been employed successfully to vaccinate cattle.We first looked into the potential of S19 to hamper the cytokine-induced maturation of DCs; however, infected cells expressed CD25, CD40, CD80, and CD86 to a comparable extent as uninfected, cytokine-matured DCs. Furthermore, S19 activated DCs in the absence of exogeneous stimuli, enhanced the expression of HLA-ABC and HLA-DR, and was able to persist intracellularly without causing cytotoxicity. Thus, DCs provide a cellular niche for persisting brucellae in vivo as a permanent source of antigen. S19-infected DCs produced IL-12/23p40, IL-12p70, and IL-10, but not IL-23. While heat-killed bacteria also activated DCs, soluble mediators were not involved in S19-induced activation of human DCs. HEK 293 transfectants revealed cellular activation by S19 primarily through engagement of Toll-like receptor (TLR)2.Thus, as an immunological prerequisite for vaccine efficacy, B. abortus S19 potently infects and potently activates (most likely via TLR2) human DCs to produce Th1-promoting cytokines.
Project description:Early production of pro-inflammatory cytokines, including IFN-?, is essential for control of blood-stage malaria infections. We have shown that IFN-? production can be induced among human natural killer (NK) cells by coculture with Plasmodium falciparum infected erythrocytes, but the importance of this response is unclear. To further explore the role of NK cells during malaria infection, we have characterized the NK-cell response of C57BL/6 mice during lethal (PyYM) or nonlethal (Py17XNL) P. yoelii infection. Ex vivo flow cytometry revealed that NK cells are activated within 24 h of Py17XNL blood-stage infection, expressing CD25 and producing IFN-?; this response was blunted and delayed during PyYM infection. CD25 expression and IFN-? production were highly correlated, suggesting a causal relationship between the two responses. Subsequent in vitro experiments revealed that IL-18 signaling is essential for induction of CD25 and synergizes with IL-12 to enhance CD25 expression on splenic NK cells. In accordance with this, Py17XNL-infected erythrocytes induced NK-cell CD25 expression and IFN-? production in a manner that is completely IL-18- and partially IL-12-dependent, and IFN-? production is enhanced by IL-2. These data suggest that IL-2 signaling via CD25 amplifies IL-18- and IL-12-mediated NK-cell activation during malaria infection.
Project description:Conventional methods to induce tolerance in humans have met with limited success. Hence, efforts to redirect tolerogen uptake using reovirus adhesin, protein sigma 1 (psigma1), may circumvent these shortcomings based upon the recent finding that when reovirus psigma1 is engineered to deliver chicken ovalbumin (OVA) mucosally, tolerance is obtained, even with a single dose. To test whether single-dose tolerance can be induced to treat EAE, proteolipid protein (PLP(130-151)) was genetically fused to OVA to psigma1 (PLP:OVA-psigma1) and shown to significantly ameliorate EAE, suppressing proinflammatory cytokines by IL-10(+) forkhead box P3 (FoxP3)(+) CD25(+)CD4(+) T(reg) and IL-4(+)CD25(-)CD4(+) Th2 cells. IL-10R or IL-4 neutralization reversed protection to EAE conferred by PLP:OVA-psigma1, and adoptive transfer of Ag-specific T(reg) or Th2 cells restored protection against EAE in recipients. Upon assessment of each relative participant, functional inactivation of CD25 impaired PLP:OVA-psigma1's protective capacity, triggering TGF-beta-mediated inflammation; however, concomitant inactivation of TGF-beta and CD25 reestablished PLP:OVA-psigma1-mediated protection by IL-28-producing FoxP3(+)CD25(-)CD4(+) T cells. Thus, psigma1-based therapy can resolve EAE independently of or dependently upon CD25 and assigns IL-28 as an alternative therapy for autoimmunity.