| 1. |
- Curbo, Sophie, et al.
(författare)
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Regulation of interleukin-4 signaling by extracellular reduction of intramolecular disulfides
- 2009
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Ingår i: Biochemical and Biophysical Research Communications - BBRC. - : Elsevier BV. - 0006-291X .- 1090-2104. ; 390:4, s. 1272-1277
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Tidskriftsartikel (refereegranskat)abstract
- Interleukin-4 (IL-4) contains three structurally important intramolecular disulfides that are required for the bioactivity of the cytokine. We show that the cell surface of HeLa cells and endotoxin-activated monocytes can reduce IL-4 intramolecular disulfides in the extracellular space and inhibit binding of IL-4 to the IL-4R alpha receptor. IL-4 disulfides were in vitro reduced by thioredoxin 1 (Trx1) and protein disulfide isomerase (PDI). Reduction of IL-4 disulfides by the cell surface of HeLa cells was inhibited by auranofin, an inhibitor of thioredoxin reductase that is an electron donor to both Trx1 and PDI. Both Trx1 and PDI have been shown to be located at the cell surface and our data suggests that these enzymes are involved in catalyzing reduction of IL-4 disulfides. The pro-drug N-acetylcysteine (NAC) that promotes T-helper type 1 responses was also shown to mediate the reduction of IL-4 disulfides. Our data provides evidence for a novel redox dependent pathway for regulation of cytokine activity by extracellular reduction of intramolecular disulfides at the cell surface by members of the thioredoxin enzyme family.
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| 2. |
- Masjedi, Khosro, 1969-
(författare)
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In vitro analyses of immune responses to metal and organic haptens in humans with contact allergy
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Contact allergy is one of the most common skin diseases with great social and economical impact. The origin and nature of contact allergens (haptens) capable of inducing T-cell mediated allergic reactions are diverse, ranging from organic molecules to metal ions. Most of the current knowledge on T-cell responses to haptens in humans with contact allergy have been established by studies on the metal ion nickel (Ni), the most common cause of contact allergy, whereas reactivity to the large group of organic haptens has been less studied.Haptens are not immunogenic by themselves but must bind carrier molecules prior to their presentation on MHC class I or II molecules and subsequent recognition by T cells. Due to differences in their chemical nature, haptens interact with host molecules by different mechanisms and differences in their solubility can influence their access to different antigen-presenting pathways.The aim of the present study was to define immune responses elicited by haptens of different chemical nature including Ni (hydrophilic metal ion), methylisothiazolinones (hydrophilic organic molecule) and parthenolide (lipophilic organic molecule). The immune response displayed by subjects with allergy to these substances, and non-allergic control subjects, was assessed by measuring hapten-induced cytokine production in peripheral blood mononuclear cells (PBMC) with a focus on ELISpot analysis of T-cell type 1 (e.g. IFN-g and IL-2) and type 2 (e.g. IL-4, IL-5 and IL-13) cytokines. For Ni and parthenolide, the phenotype of the hapten-reactive T cells was determined. The allergic status of subjects was defined by clinical history and patch testing. The latter is the established diagnostic method for contact allergy, based on applying various haptens to the subjects’ back and grading the skin reaction after 2-3 days.All three haptens elicited a concomitant T-cell type 1 and 2 response in subjects with contact allergy to the corresponding hapten, suggesting the induction of a functionally related cytokine profile, irrespective of the chemical character of the hapten. The cytokine response was related to the degree of the subjects’ patch test reactivity; PBMC from a vast majority of subjects with strong and moderate patch test reactivity displayed detectable cytokine responses to the corresponding haptens, whereas subjects with weak or no (controls) patch test reactivity did not. Despite the similar cytokine profile induced, the phenotype of the reactive T cells was found to differ between haptens with Ni eliciting CD4+ T cells and parthenolide eliciting CD8+ T cells. This difference may be explained by a better ability of a lipophilic hapten to gain access to the MHC class I-restricted antigen-presentation pathway. Moreover, the data suggest that analysis of cytokine responses to haptens may facilitate future development of in vitro-based diagnostics assay for contact allergy.Finally, the relationship between the variation over time in patch test reactivity and systemic reactivity to Ni, in terms of cytokine responses to Ni in vitro, was investigated. The degree of patch test reactivity is known to vary over time, in particular in subjects with weak reactivity. Ni-allergic subjects were patch tested three times with three month intervals and PBMC obtained at the same time points were assessed for in vitro reactivity to Ni. The overall reactivity in the patch test and the in vitro test was well correlated confirming that both methods provide a good and comparable estimate of the systemic reactivity to Ni. However, fluctuations in the patch test reactivity over time were not well correlated with variations in the cytokine response elicited in vitro suggesting that other parameters besides changes in the systemic reactivity could significantly contribute to the variation in patch test reaction over time.
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| 3. |
- Minang, Jacob, 1975-
(författare)
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Cytokine responses in metal-induced allergic contact dermatitis : Relationship to in vivo responses and implication for in vitro diagnosis
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Transition metals such as nickel (Ni), cobalt (Co), palladium (Pd), chromium (Cr) and gold (Au) are widely used as alloys in jewelry and biomaterials such as orthodontic and orthopaedic appliances. These metals also cause cell-mediated allergic contact dermatitis (ACD) reactions in a significant proportion of the population upon prolonged direct exposure. The immune mechanisms underlying the response to these metals are not yet well defined. In the studies described in this thesis we therefore investigated the profile of cytokine responses to various metal ions in vitro and the relationship with the ACD reaction in vivo. In the first study, we investigated the relationship between the profile and magnitude of Ni2+-induced cytokine responses in vitro and the degree of in vivo reactivity to Ni2+. PBMC from Ni2+-reactive (ACD) and non-reactive control subjects were cultured with or without NiCl2. The numbers of IL-4-, IL-5- and IL-13-producing cells and the concentrations of IFN-γ, IL-10 and IL-13 produced were analysed by ELISpot and ELISA respectively. Ni2+ elicited a mixed Th1- and Th2-type cytokine profile in PBMC from ACD subjects with a positive correlation observed between the levels of the elicited cytokines and the degree of patch test reactivity. Hence, suggesting an involvement of both Th1- and Th2-type cytokines in ACD to Ni2+ and a direct association between the magnitude of the Ni2+-induced cytokine response overall and the in vivo reactivity to Ni2+. The impact of the regulatory cytokine IL-10 on Ni2+-induced Th1- and Th2-type cytokine responses in human PBMC was investigated in the next study. PBMC from blood donors with a history of Ni2+ reactivity and non-reactive control donors were stimulated with Ni2+ ex vivo with or without addition of human recombinant IL-10 (rIL-10) or neutralising mAb to IL-10. Depletion/enrichment experiments were performed to phenotype the Ni2+-specific cytokine producing cells. Exogenous rIL-10 significantly down-regulated the production of all cytokines but with a more pronounced effect on IFN-γ. IL-10 neutralisation, on the other hand, enhanced the levels of Ni2+-induced IFN-γ only. Ni2+-specific cytokine-producing cells in PBMC were found to be predominantly CD4+ T cells. Thus, IL-10 may play a regulatory role in vivo by counteracting the ACD reactions mediated by CD4+ T cells producing Th1-type cytokines. In the third study, we investigated the relationship between in vivo patch test reactivity to a number of metals (Ni, Co, Pd, Cr and Au) included in the standard and/or dental patch test series and in vitro responses to the metals in question. PBMC from metal patch test positive and negative control subjects were stimulated with a panel of eight metal salts and cytokine responses analysed by ELISpot and/or ELISA. A mixed Th1- (IL-2 and/or IFN-γ) and Th2-type (IL-4 and/or IL-13) cytokine profile was observed in PBMC from most metal allergic subjects upon in vitro stimulation with the metal(s) to which the subject was patch test positive. Our data suggest that other metals included in the standard and dental patch test series, just like Ni2+, induce a mixed Th1- and Th2-type cytokine profile in PBMC from ACD subjects in vitro. We further developed a simplified ELISpot protocol utilising plates precoated with capture monoclonal antibodies (mAb) and subsequent detection in one step using enzyme-labelled mAb, for enumerating the frequency of allergen (Ni2+)-specific cytokine producing cells. This was compared with a regular ELISpot protocol, with an overnight incubation for capture mAb adsorbtion and detection with biotinylated mAb followed by enzyme-labelled streptavidin. PBMC from Ni2+-reactive and non-reactive subjects were incubated with or without NiCl2 and the enumeration of cells producing IFN-γ, IL-4 or IL-13 by the two protocols were compared. PBMC from Ni2+-reactive subjects showed significantly higher Ni2+-induced IL-4 and IL-13 responses and the number of antigen-specific cytokine-producing cells determined by the two ELISpot protocols correlated well. In a nutshell, our data point to the potential use of in vitro cytokine assays as diagnostic tools in distinguishing ACD subjects sensitised to different metals and non-sensitised subjects.
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