Recognition of a novel naturally processed, A2 restricted, HCV-NS4 epitope triggers IFN-gamma release in absence of detectable cytopathicity

Using short term CTL lines derived from HLA A2/K^b transgenic mice and IFN-gamma release assays we demonstrate that the NS4.1769 epitope, is generated from natural processing of the NS4 antigen, and presented in the context of the A2/K^b molecules. Interestingly, T cell recognition of the naturally processed form of the NS4.1769 epitope was associated with significant IFN-gamma release, but no direct cytolytic activity. Epitopes of this phenotype might be of interest, in terms of therapy of chronic HCV infection by associating the benefit of localized lymphokine release with low or absent direct cytopathicity.     

Regulatory effects of antihistamines on the responses to staphylococcal enterotoxin B of human monocyte-derived dendritic cells and CD4+ T cells

BACKGROUND: Antihistamines are widely used for the treatment of allergic diseases, such as urticaria and allergic rhinitis. They are also effective for the treatment of diseases in which T cells are mainly involved in the pathogenesis, such as atopic dermatitis (AD) and contact dermatitis. Dendritic cells (DCs) drive polarization of naive T cells into Th1 or Th2 subsets, and are also likely to be involved in AD pathogenesis. OBJECTIVES: The aim of this study was to determine the effects of antihistamines on DCs and CD4(+) T cells. METHODS: Human monocyte-derived DCs (MoDCs) and autologous CD4(+) T cells were obtained from healthy subjects, and cultured together or independently in the presence of antihistamines. As a stimulant, we used staphylococcal enterotoxin B or the combination of anti-CD3 monoclonal antibody (mAb) and anti-CD28 mAb. The concentrations of cytokines and chemokines in culture supernatants were measured by ELISA. The expression of surface molecules on MoDCs was measured by flow cytometry. Cell proliferation in the cocultures of MoDCs and CD4(+) T cells (DC-T cocultures) was measured by a [(3)H] thymidine incorporation assay. RESULTS: Antihistamines inhibited the production of IFN-gamma, and enhanced the production of IL-4 in DC-T cocultures. Antihistamines inhibited the production of TNF-alpha, TARC, MDC, IP-10, and Mig from MoDCs. Epinastine, one of antihistamines, suppressed the expression of ICAM-1 (CD54) on MoDCs. Epinastine also inhibited the proliferation of CD4(+) T cells cocultured with MoDCs. CONCLUSIONS: Our findings show that antihistamines regulate immune responses by affecting the interaction between DCs and CD4(+) T cells, and further DCs and CD4(+) T cells independently, which may partially contribute to the control of allergic diseases such as AD and contact dermatitis.     

Evaluation of IFN-γ secretion after stimulation with C. neoformans and C. gattii antigens in individuals with frequent exposure to the fungus

In this study we produced antigenic extracts from prototypical strains of C. neoformans (VNI-VNIV) and C. gattii (VGI-VGIV) and tested IFN-γ secretion by Elispot. Antigens from the eight Cryptococcus molecular types (VNI –VNIV and VGI - VGIV) were obtained after capsule reduction. IFN-γ secretion by Elispot method were stimulated with C. neoformans and C. gattii antigens. Peripheral blood mononuclear cells of fourteen healthy control subjects, being: five ecotourists, two mycologists, three poultry keepers, and four individuals without reports of exposure to the fungus. We observed a significant increase in IFN-γ secretion in the group of ecotourists, mycologists and bird keepers in relation to the group of individuals without reports of occupational exposures to these agents. Our results suggest the significant increase in IFN-γ secretion may be related to the continuous exposure of these groups of individuals to the fungus, as well as to the specific antigen memory immune response developed during exposure to Cryptococcus.     

The effect of IκK-16 on lipopolysaccharide-induced impaired monocytes

This study focuses on impaired monocyte function, which occurs in some patients after trauma, major elective surgery, or sepsis. This monocyte impairment increases the risk of secondary infection and death. We aimed to determine the influence IκK-16 had on monocytes using an ex-vivo model of human monocyte impairment. We included the effects of the well-studied comparators interferon-gamma (IFN-γ) and granulocyte-macrophage colony-stimulating factor (GM-CSF) on impaired monocytes. Primary human monocytes were stimulated with 10 ng/mL of lipopolysaccharide (LPS) for 16 h and then challenged with 100 ng/mL LPS to assess the monocyte inflammatory response. Treatment regimens, consisting of either IκK-16, IFN-γ, or GM-CSF, were administered to impaired monocytes near the time of initial LPS stimulation. Stimulation with 10 ng/mL LPS initially promoted a pro-inflammatory response but subsequently impaired production of both tumor necrosis factor-α (TNF-α) and interleukin-10 (IL-10) and decreased HLA-DR expression. IκK-16 treatment attenuated TNF-α production and programmed death-ligand 1 (PD-L1) expression and increased IL-10 and CD14 expression. IFN-γ treatment increased TNF-α production as well as PD-L1 and HLA-DR expression. In conclusion, limiting early inflammation with IκK-16 suppresses TNF-α production and PD-L1 expression but enhances IL-10 production and preserves CD14 expression for potential future exposure to infective stimuli.     

Interferon-gamma inhibits intestinal restitution by preventing gap junction communication between enterocytes

BACKGROUND & AIMS: Necrotizing enterocolitis (NEC) is characterized by interferon-gamma (IFN-gamma) release and inadequate intestinal restitution. Because enterocytes migrate together, mucosal healing may require interenterocyte communication via connexin 43-mediated gap junctions. We hypothesize that enterocyte migration requires interenterocyte communication, that IFN impairs migration by impairing connexin 43, and that impaired healing during NEC is associated with reduced gap junctions. METHODS: NEC was induced in Swiss-Webster or IFN(-/-) mice, and restitution was determined in the presence of the gap junction inhibitor oleamide, or via time-lapse microscopy of IEC-6 cells. Connexin 43 expression, trafficking, and localization were detected in cultured or primary enterocytes or mouse or human intestine by confocal microscopy and (35)S-labeling, and gap junction communication was assessed using live microscopy with oleamide or connexin 43 siRNA. RESULTS: Enterocytes expressed connexin 43 in vitro and in vivo, and exchanged fluorescent dye via gap junctions. Gap junction inhibition significantly reduced enterocyte migration in vitro and in vivo. NEC was associated with IFN release and loss of enterocyte connexin 43 expression. IFN inhibited enterocyte migration by reducing gap junction communication through the dephosphorylation and internalization of connexin 43. Gap junction inhibition significantly increased NEC severity, whereas reversal of the inhibitory effects of IFN on gap junction communication restored enterocyte migration after IFN exposure. Strikingly, IFN(-/-) mice were protected from the development of NEC, and showed restored connexin 43 expression and intestinal restitution. CONCLUSIONS: IFN inhibits enterocyte migration by preventing interenterocyte gap junction communication. Connexin 43 loss may provide insights into the development of NEC, in which restitution is impaired.     

牙周基础治疗对口腔扁平苔藓伴慢性牙周炎患者外周血MMP-3及IFN-γ水平的影响

目的:观察牙周基础治疗前后口腔扁平苔藓伴慢性牙周炎患者血清中基质金属蛋白酶-3(MMP-3)和干扰素-γ(IFN-γ)浓度的变化.方法:选取60例诊断为伴有牙周炎的糜烂型口腔扁平苔藓患者,随机分为2组,其中实验组30例进行牙周基础治疗联合药物治疗,治疗前后,检测牙周指数PD、AL、BI和PLI.对照组30例采取药物治疗.用ELLSA检测治疗前后2组患者血清中MMP-3及IFN-γ的表达水平,分析各组细胞因子浓度的差异.结果:治疗后实验组牙周指数明显下降(P＜0.05);2组患者血清中的MMP-3及IFN-γ表达水平与治疗前相比下降(P＜0.05);经过治疗后,实验组MMP-3及IFN-γ表达水平下降趋势较对照组明显(P＜0.05).结论:牙周基础治疗在口腔扁平苔藓治疗中起到了积极作用,可有效降低炎症水平.     

Lactobacillus rhamnosus GG prevents epithelial barrier dysfunction induced by interferon-gamma and fecal supernatants from irritable bowel syndrome patients in human intestinal enteroids and colonoids

Disruption of intestinal barrier homeostasis is an important pathogenic factor in conditions such as irritable bowel syndrome (IBS). Lactobacillus rhamnosus GG (LGG) improves IBS symptoms through unclear mechanisms. Previous studies utilizing colorectal adenocarcinoma cell lines showed that LGG metabolites prevented interferon gamma (IFN-gamma) induced barrier damage but the model employed limited these findings. We aimed to interrogate the protective effects of LGG on epithelial barrier function using human intestinal epithelial cultures (enteroids and colonoids) as a more physiologic model. To investigate how LGG affects epithelial barrier function, we measured FITC-Dextran (FD4) flux across the epithelium as well as tight junction zonula occludens 1 (ZO-1) and occludin (OCLN) expression. Colonoids were incubated with fecal supernatants from IBS patients (IBS-FSN) and healthy controls in the presence or absence of LGG to examine changes in gut permeability. Enteroids incubated with IFN-gamma demonstrated a downregulation of OCLN and ZO-1 expression by 67% and 50%, respectively (p<0.05). This was accompanied by increased paracellular permeability as shown by leakage of FD4. Pretreatment of enteroids with LGG prevented these changes and normalized OCLN and ZO-1 to control levels. These actions were independent of its action against apoptosis. However, these protective effects were not seen with LGG cell wall extracts, LGG DNA, or denatured (boiled) LGG. Intriguingly, IBS-FSN injected into colonoids increased paracellular permeability, which was prevented by LGG. LGG, likely due to secreted proteins, protects against epithelial barrier dysfunction. Bacterial-derived factors to modulate gut barrier function may be a treatment option in disorders such as IBS.     

Interferons induce an antiviral state in human pancreatic islet cells

Enterovirus infections, in particular those with Coxsackieviruses, have been linked to the development of type 1 diabetes (T1D). Although animal models have demonstrated that interferons (IFNs) regulate virus-induced T1D by acting directly on the beta cell, little is known on the human pancreatic islet response to IFNs. Here we show that human islet cells respond to IFNs by expressing signature genes of antiviral defense. We also demonstrate that they express three intracellular sensors for viral RNA, the toll like receptor 3 (TLR3) gene, the retinoic acid-inducible gene I (RIG-I) and the melanoma differentiation-associated gene-5 (MDA-5), which induce type I IFN production in infected cells. Finally, we show for the first time that the IFN-induced antiviral state provides human islets with a powerful protection from the replication of Coxsackievirus. This may be critical for beta cell survival and protection from virus-induced T1D in humans.