Role of IL-27-producing dendritic [corrected] cells in Th1-immunity polarization in Lewis rats

Lewis and Brown Norway rats are entirely different with respect to the polarization of their immune responses (Th1 and Th2, respectively). We found that naive Lewis rat splenocytes treated in vitro with heat-killed Mycobacterium tuberculosis (Mtb) upregulate the expression of both subunits of IL-27 (IL-27p28 and EBI3). Mtb treatment caused naive Lewis rat splenocytes to express 4.6-fold more IL-27p28 than Mtb-treated Brown Norway rat splenocytes 6h after the treatment. Although WSX-1, the IL-27 receptor, was not induced by Mtb treatment in splenocytes from either rat strain, Lewis rats expressed significantly higher levels of the IL-27 signal transducers T-bet and IL-12Rbeta2 than Brown Norway rats. Flow cytometric analysis of dendritic cells from bone marrow cells revealed Lewis rats had more IL-27p28-positive cells. Thus, early in the immune response, Lewis rats appear to produce higher levels of IL-27 than Brown Norway rats, resulting in polarization towards Th1-immunity.     

In vitro Th1 cytokine-independent Th2 suppressive effects of bifidobacteria

A comparison between 17 strains of lactic acid bacteria and 15 strains of bifidobacteria indicated that bifidobacteria induced significantly lower levels of interleukin-12 (IL-12) in murine splenic cells. The present study aims to evaluate the effect and mechanism of Bifidobacterium longum BB536, a probiotic strain, in suppressing antigen-induced Th2 immune response in vitro. BB536 suppressed immunoglobulin (Ig) E and IL-4 production by ovalbumin-sensitized splenic cells, but induction of Th1-inducing cytokine production, such as IL-12 and gamma interferon (IFN-gamma) tended to be lower compared with lactic acid bacteria. Neutralization with antibodies to IL-12, IFN-gamma, IL-10 and transforming growth factor beta indicated negative involvement of Th1-inducing cytokines and regulatory cytokines in the suppression of Th2 immune response by BB536, especially when treated at higher doses of BB536 (>10 microg cells/ml). Furthermore, BB536 induced the maturation of immature bone marrow-derived dendritic cells (BM-DCs), and suppressed antigen-induced IL-4 production mediated by BM-DCs. These results suggested that BB536 suppressed Th2 immune responses, partially independent of Th1-inducing cytokines and independent of regulatory cytokines, mediated by antigen-presenting cells such as dendritic cells.     

Analysis of IL-12 receptor beta 2 chain expression of circulating T lymphocytes in patients with atopic asthma

Th2 cell predominance relative to Th1 cells contributes to pathological immune responses in patients with atopic asthma. IL-12 is a key cytokine in the induction of Th1 cells, and downregulation of IL-12 production is reported in these patients. However, IL-12 receptor expression of their T lymphocytes has not been clarified. In this study, expression of IL-12 receptor beta 2 on T cells and secretion of cytokines which affect IL-12 receptor beta 2 expression by their PBMC were examined. We found that IL-12 receptor beta 2 expression of the T cells is reduced. This is partly due to the diminished production of IL-12 and enhanced secretion of IL-4 by their PBMC. IL-18 production is not significantly modulated in these patients. Furthermore, intrinsic defects of the CD4(+) T cells, which reduce their IL-12 receptor beta 2 expression in response to IL-12 and/or IL-18 stimulation, are evident and are importantly involved in the Th1/Th2 imbalance of patients with atopic asthma.     

The CD8 T cell compartment plays a dominant role in the deficiency of Brown-Norway rats to mount a proper type 1 immune response.

Differential cytokine production by T cells plays an important role in regulating the nature of an immune response. In the rat, Brown-Norway (BN) and Lewis (LEW) strains differ markedly in their susceptibility to develop either type 1 or type 2-mediated autoimmune manifestations. BN rats are susceptible to type 2-dependent systemic autoimmunity, while LEW rats are resistant. Conversely, type 1-mediated, organ-specific autoimmune disease can be easily induced in LEW, but not in BN, rats. The mechanisms involved in the differential development of type 1 and type 2 immune responses by these two strains are still unknown. In the present study we analyzed the contributions of APC, CD4 and CD8 T cells, and MHC molecules in the difference between LEW and BN rats to develop a type 1 immune response. First, we show that the defect of BN T cells to produce type 1 cytokines in vitro does not require the presence of APC and, by using an APC-independent stimulation assay, we have localized the defect within the T cell compartment. Both CD4 and CD8 T cells are involved in the defect of BN rats to develop a type 1 immune response with a major contribution of the CD8 T cell compartment. This defect is associated with an increase in the type 2 cytokine IL-4 in both BN T cell populations, but neutralization of this cytokine does not restore this defect. Finally, by using MHC congenic rats, we show that the MHC haplotype is not involved in the defect of BN T cells to mount a proper type 1 cytokine response.     

Functional and genetic analysis of two CD8 T cell subsets defined by the level of CD45RC expression in the rat

Differential cytokine production by T cells plays an important role in the outcome of the immune response. We show that the level of CD45RC expression differentiates rat CD8 T cells in two subpopulations, CD45RC(high) and CD45RC(low), that have different cytokine profiles and functions. Upon in vitro stimulation, in an Ag-presenting cell-independent system, CD45RC(high) CD8 T cells produce IL-2 and IFN-gamma while CD45RC(low) CD8 T cells produce IL-4, IL-10, and IL-13. In vitro, these subsets also exhibit different cytotoxic and suppressive functions. The CD45RC(high)/CD45RC(low) CD8 T cell ratio was determined in Lewis (LEW) and Brown-Norway (BN) rats. These two rat strains differ with respect to the Th1/Th2 polarization of their immune responses and to their susceptibility to develop distinct immune diseases. The CD45RC(high)/CD45RC(low) CD8 T cell ratio is higher in LEW than in BN rats, and this difference is dependent on hemopoietic cells. Linkage analysis in a F(2)(LEW x BN) intercross identified two quantitative trait loci on chromosomes 9 and 20 controlling the CD45RC(high)/CD45RC(low) CD8 T cell ratio. This genetic control was confirmed in congenic rats. The region on chromosome 9 was narrowed down to a 1.2-cM interval that was found to also control the IgE response in a model of Th2-mediated disorder. Identification of genes that control the CD45RC(high)/CD45RC(low) CD8 T cell subsets in these regions could be of great interest for the understanding of the pathophysiology of immune-mediated diseases.     

Accessory function of human mononuclear phagocytes for lymphocyte responses to the superantigen staphylococcal enterotoxin B.

The role of the cytokines IL-1 alpha, IL-1 beta, and IL-6 and the cell adhesion molecules ICAM-1, LFA-1 (alpha and beta), and Mac-1 as accessory molecules for stimulation of T cells by the superantigen staphylococcal enterotoxin B (SEB) was examined. Both blood monocytes and alveolar macrophages were used as accessory cells because these cells differ in patterns of cytokine expression and thus potentially in accessory cell function for superantigens. The blastogenic response of highly purified T cells to SEB was reconstituted with either monocytes or alveolar macrophages. IL-1 secretion was increased comparably in monocytes and alveolar macrophages by SEB, but IL-6 was not stimulated by SEB. IL-1 alpha plus IL-1 beta reconstituted the response of T cells to SEB but required the addition of accessory cells. The cell adhesion molecules ICAM-1 and LFA-1 but not Mac-1 also functioned as accessory molecules for SEB-induced cluster formation and lymphocyte blastogenesis. Thus, not only must this superantigen bind to Class II MHC on accessory cells as is well known, but also SEB requires at least certain cytokines (IL-1 alpha and IL-1 beta) produced by accessory cells and cell adhesion molecules (ICAM-1 and LFA-1) for activation of T lymphocytes.     

Zinc modulates mRNA levels of cytokines

Zinc plays an important role in cell-mediated immune function. Altered cellular immune response resulting from zinc deficiency leads to frequent microbial infections, thymic atrophy, decreased natural killer activity, decreased thymic hormone activity, and altered cytokine production. In this study, we examined the effect of zinc deficiency on IL-2 and IFN-gamma in HUT-78 (Th0) and D1.1 (Th1) cell lines and TNF-alpha, IL-1 beta, and IL-8 in the HL-60 (monocyte-macrophage) cell line. The results demonstrate that zinc deficiency decreased the levels of IL-2 and IFN-gamma cytokines and mRNAs in HUT-78 after 6 h of PMA/p-phytohemagglutinin (PHA) stimulation and in D1.1 cells after 6 h of PHA/ionomycin stimulation compared with the zinc-sufficient cells. However, zinc deficiency increased the levels of TNF-alpha, IL-1 beta, and IL-8 cytokines and mRNAs in HL-60 cells after 6 h of PMA stimulation compared with zinc-sufficient cells. Actinomycin D study suggests that the changes in the levels of these cytokine mRNAs were not the result of the stability affected by zinc but might be the result of altered expression of these cytokine genes. These data demonstrate that zinc mediates positively the gene expression of IL-2 and IFN-gamma in the Th1 cell line and negatively TNF-alpha, IL-1 beta, and IL-8 in the monocyte-macrophage cell line. Our study shows that the effect of zinc on gene expression and production of cytokines is cell lineage specific.     

Experimental autoimmune myasthenia gravis may occur in the context of a polarized Th1- or Th2-type immune response in rats.

Experimental autoimmune myasthenia gravis (EAMG) is a T cell-dependent, Ab-mediated autoimmune disease induced in rats by a single immunization with acetylcholine receptor (AChR). Although polarized Th1 responses have been shown to be crucial for the development of mouse EAMG, the role of Th cell subsets in rat EAMG is not well established. In the present work we show that while the incidence and severity of EAMG are similar in Lewis (LEW) and Brown-Norway (BN) rats, strong differences are revealed in the immune response generated. Ag-specific lymph node cells from LEW rats produced higher amounts of IL-2 and IFN-gamma than BN lymph node cells, but expressed less IL-4 mRNA. IgG1 and IgG2b anti-AChR isotype predominated in BN and LEW rats, respectively, confirming the dichotomy of the immune response observed between the two strains. Furthermore, although IL-12 administration or IFN-gamma neutralization strongly influenced the Th1/Th2 balance in BN rats, it did not affect the disease outcome. These data demonstrate that a Th1-dominated immune response is not necessarily associated with disease severity in EAMG, not only in rats with disparate MHC haplotype but also in the same rat strain, and suggest that in a situation where complement-fixing Ab can be generated as a consequence of either Th1- or Th2-mediated T cell help, deviation of the immune response will not be an adequate strategy to prevent this Ab-mediated autoimmune disease.     

Allergen rush immunotherapy increases interleukin (IL)-12 production and IL-12 receptor beta2 chain expression in patients with allergic asthma

Interleukin (IL)-12 production and IL-12 receptor (IL-12R) beta2 chain expression were investigated in patients with allergic asthma successfully treated with rush immunotherapy (RIT) and control patients with mild allergic asthma. Peripheral blood mononuclear cells (PBMCs) were stimulated with Dermatophagoides farinae (Der f), and production of cytokines was measured. Furthermore, the effects of cytokines on IL-12R beta2 chain expression on CD4(+) T cells were investigated. Production by PBMCs of IL-12 and IFN-gamma was significantly higher and production of IL-4 was significantly lower after stimulation with Der f allergen in RIT-treated patients than in control patients. Significant increases in the expression of IL-12R beta2 chain before and after stimulation of CD4(+) T cells with IL-12 or IFN-gamma were observed in RIT-treated patients compared with that in control patients. Allergen RIT increases IL-12 production and IL-12R beta2 chain expression and thus may convert cytokine production from Th2 to Th1 or Th0 type in allergic asthma.     

N-acetyl tryptophan glucopyranoside (NATG) as a countermeasure against gamma radiation-induced immunosuppression in murine macrophage J774A.1 cells

Radiation exposure to immune system induces imbalance in cytokines expression involved in Th1/Th2 homeostasis perturbations. In the present study, N-acetyl tryptophan glucoside (NATG), a bacterial secondary metabolite, was evaluated for its possible radioprotective potential to immune system using J774A.1 murine macrophages. In this study, expression of IFN-γ, TNF-α, IL-10, IL-2, IL-12, IL-13 and IL-17A cytokines was analyzed in irradiated and NATG pretreated cells using ELISA assay. Results of the study indicated that irradiated macrophages (NK-1R^+?cells) pretreated with NATG showed higher (p?相似文献   

CD28, Ox-40, LFA-1, and CD4 modulation of Th1/Th2 differentiation is directly dependent on the dose of antigen

The involvement of specific accessory/costimulatory molecules in differentiation to Th1 and Th2 phenotypes is controversial. Reports suggest that molecules such as CD4, CD28, and Ox-40 support Th2 differentiation and suppress Th1 differentiation, whereas others such as LFA-1 support Th1 responses and suppress Th2 responses. We have previously defined an in vitro model of differentiation that is absolutely dependent on the initial dose and affinity of peptide presented to a naive CD4 cell. The dose and affinity of Ag regulate autocrine production of IL-2, IL-4, and IFN-gamma, which in turn govern differentiation to Th1 and Th2 phenotypes. We have used this system to confirm that CD4, CD28, and Ox-40 interactions can promote, and LFA-1 interactions can suppress, differentiation of cells secreting the Th2 cytokines IL-5 and IL-13. However, for CD4 and LFA-1, this is only seen over a certain range of peptide doses. In addition, CD28 and Ox-40 interactions also promote Th1 differentiation. In general, agonist Abs to accessory molecules shifted the response curves for IFN-gamma, IL-5, and IL-13 to lower doses, whereas antagonist reagents resulted in similar curves shifted toward the higher doses. We conclude that ligation of cell surface accessory receptors enables low doses of Ag to promote responses normally induced only by higher doses. Individual receptors do not intrinsically regulate one cytokine phenotype or another, suggesting that differentiation is controlled by the level of expression of multiple accessory molecule pairs integrated with the number and affinity of peptide/MHC complexes.     

Proinflammatory and Th2-derived cytokines modulate CD40-mediated expression of inflammatory mediators in airway epithelia: implications for the role of epithelial CD40 in airway inflammation

Cytokines produced by activated macrophages and Th2 cells within the lung play a key role in asthma-associated airway inflammation. Additionally, recent studies suggest that the molecule CD40 modulates lung immune responses. Because airway epithelial cells can act as immune effector cells through the expression of inflammatory mediators, the epithelium is now considered important in the generation of asthma-associated inflammation. Therefore, the goal of the present study was to examine the effects of proinflammatory and Th2-derived cytokines on the function of CD40 in airway epithelia. The results show that airway epithelial cells express CD40 and that engagement of epithelial CD40 induces a significant increase in expression of the chemokines RANTES, monocyte chemoattractant protein (MCP-1), and IL-8 and the adhesion molecule ICAM-1. Cross-linking epithelial CD40 had no effect on expression of the adhesion molecule VCAM-1. The proinflammatory cytokines TNF-alpha and IL-1beta and the Th2-derived cytokines IL-4 and IL-13 modulated the positive effects of CD40 engagement on inflammatory mediator expression in airway epithelial cells. Importantly, CD40 ligation enhanced the sensitivity of airway epithelial cells to the effects of TNF-alpha and/or IL-1beta on expression of RANTES, MCP-1, IL-8, and VCAM-1. In contrast, neither IL-4 nor IL-13 modified the effects of CD40 engagement on the expression of RANTES, MCP-1, IL-8, or VCAM-1; however, both IL-4 and IL-13 attenuated the effects of CD40 cross-linking on ICAM-1 expression. Together, these findings suggest that interactions between CD40-responsive airway epithelial cells and CD40 ligand+ leukocytes, such as activated T cells, eosinophils, and mast cells, modulate asthma-associated airway inflammation.     

Proinflammatory cytokines in bovine colostrum potentiate the mitogenic response of peripheral blood mononuclear cells from newborn calves through IL-2 and CD25 expression

Abstract: Bovine colostrum contains high concentrations of cytokines, and colostral cytokines are considered to be an important factor in stimulation of maturation of the immune system in newborns. In this study, 5 proinflammatory cytokines (IL-1beta, IL-6, TNF-alpha, IFN-gamma and IL-1 receptor antagonist, IL-1ra) present in colostrum were tested for their potential to enhance mitogenic response and to elicit expression of IL-2 mRNA and CD25 in peripheral blood mononuclear cells (PBMC) from newborn calves before being fed colostrum. PBMC were pretreated with each recombinant bovine cytokine for 2 hr before stimulation with concanavalin A (ConA). Pretreatment of PBMC from newborn calves with IL-1beta, TNF-alpha or IFN-gamma significantly enhanced the ConA response, whereas IL-1ra inhibited the response. The degree of enhancement or inhibition of mitogenic response by these cytokines was more pronounced in PBMC from newborn calves than in those from adult cows. Although IL-2 mRNA expression in ConA-stimulated PBMC from newborn calves was weaker than that in those from adult cows of ConA-stimulated controls, the expression levels became comparable after pretreatment with IL-1beta, TNF-alpha or IFN-gamma. The CD25 expression in PBMC from newborn calves was also enhanced by pretreatment with IL-1beta, TNF-beta and IFN-gamma. These results suggest that pretreatment of neonatal PBMC with IL-1beta, TNF-alpha or IFN-gamma promotes mitogenic response to ConA through up-regulating the production of IL-2 and the expression of the mature IL-2 receptor.     

The balance between CD45RChigh and CD45RClow CD4 T cells in rats is intrinsic to bone marrow-derived cells and is genetically controlled

The level of CD45RC expression differentiates rat CD4 T cells in two subpopulations, CD45RC(high) and CD45RC(low), that have different cytokine profiles and functions. Interestingly, Lewis (LEW) and Brown Norway (BN) rats, two strains that differ in their ability to mount type 1 and type 2 immune responses and in their susceptibility to autoimmune diseases, exhibit distinct CD45RC(high)/CD45RC(low) CD4 T cell ratios. The CD45RC(high) subpopulation predominates in LEW rats, and the CD45RC(low) subpopulation in BN rats. In this study, we found that the antiinflammatory cytokines, IL-4, IL-10, and IL-13, are exclusively produced by the CD45RC(low) CD4 T cells. Using bone marrow chimeras, we showed that the difference in the CD45RC(high)/CD45RC(low) CD4 T cell ratio between naive LEW and BN rats is intrinsic to hemopoietic cells. Furthermore, a genome-wide search for loci controlling the balance between T cell subpopulations was conducted in a (LEW x BN) F(2) intercross. Genome scanning identified one quantitative trait locus on chromosome 9 (approximately 17 centiMorgan (cM); log of the odds ratio (LOD) score 3.9). In addition, two regions on chromosomes 10 (approximately 28 cM; LOD score 3.1) and 20 (approximately 40 cM; LOD ratio score 3) that contain, respectively, a cytokine gene cluster and the MHC region were suggestive for linkage. Interestingly, overlapping regions on these chromosomes have been implicated in the susceptibility to various immune-mediated disorders. The identification and functional characterization of genes in these regions controlling the CD45RC(high)/CD45RC(low) Th cell subpopulations may shed light on key regulatory mechanisms of pathogenic immune responses.     

Inhibition of myeloid dendritic cell accessory cell function and induction of T cell anergy by alcohol correlates with decreased IL-12 production

Alcohol consumption inhibits accessory cell function and Ag-specific T cell responses. Myeloid dendritic cells (DCs) coordinate innate immune responses and T cell activation. In this report, we found that in vivo moderate alcohol intake (0.8 g/kg of body weight) in normal volunteers inhibited DC allostimulatory capacity. Furthermore, in vitro alcohol treatment during DC differentiation significantly reduced allostimulatory activity in a MLR using naive CD4(+) T cells, and inhibited tetanus toxoid Ag presentation by DCs. Alcohol-treated DCs showed reduced IL-12, increased IL-10 production, and a decrease in expression of the costimulatory molecules CD80 and CD86. Addition of exogenous IL-12 and IL-2, but not neutralization of IL-10, during MLR ameliorated the reduced allostimulatory capacity of alcohol-treated DCs. Naive CD4(+) T cells primed with alcohol-treated DCs showed decreased IFN-gamma production that was restored by exogenous IL-12, indicating inhibition of Th1 responses. Furthermore, CD4(+) T cells primed with alcohol-treated DCs were hyporesponsive to subsequent stimulation with the same donor-derived normal DCs, suggesting the ability of alcohol-treated DCs to induce T cell anergy. LPS-induced maturation of alcohol-treated immature DCs partially restored the reduced allostimulatory activity, whereas alcohol given only during DC maturation failed to inhibit DC functions, suggesting that alcohol primarily impairs DC differentiation rather than maturation. NFkappaB activation, a marker of DC maturation was not affected by alcohol. Taken together, alcohol both in vitro and in vivo can impair generation of Th1 immune responses via inhibition of DC differentiation and accessory cell function through mechanisms that involve decreased IL-12 induction.     

Immunology of interactions between ticks and hosts

Abstract Infestation with ixodid tick stimulates the immune regulatory and effector pathways of the hosts involving antigen presenting cells, T-lymphocytes, B-lymphocytes, basophils, mast cells, eosinophils and a variety of bioactive molecules like cytokines, antibodies and complement. Tick-mediated immunosuppression has been investigated using cells derived from infested animals and by exposing cells from uninfested animals to tick salivary gland molecules. Tick-induced suppression of host immune defences is characterized by reduced ability of lymphocytes from infested animals to proliferate m vitro in the presence of concanavalin A (Con A), diminished primary antibody responses to T-cell dependent antigen, and decreased elaboration of macrophage (IL-1 and TNF-α) and Th 1 -lymphocyte cytokines (IFN-γ), whereas Th2 cytokines production (IL-4, IL-5 and IL-10) isenhanced. It is known that IL-10 inhibits Thl cell development and also reduces the in vitro T-lymphocyte proliferative response to Con A stimulation. Proteins which inhibited T-lymphocyte in vitro responsiveness to Con A were also isolated from tick salivary glands.     

T cell zones of lymphoid organs constitutively express Th1 cytokine mRNA: specific changes during the early phase of an immune response

The cytokine milieu of the T cell zones in lymphoid organs is involved in the activation of naive T cells. Quantitative data regarding the local expression of cytokines are lacking. Therefore, the expression of Th1 (IL-2, IL-12p40, IFN-gamma), Th2 (IL-4, IL-10), as well as TGFbeta1 and IL-15 mRNA was studied after laser microdissection in the steady state and during an immune response in rats. Our results show that Th1 cytokines are preferentially found in lymphoid tissues and in the T cell zones, whereas Th2 cytokines are expressed throughout the organs and especially in the B cell zones. After injection of sheep RBC, IL-2 and IFN-gamma mRNA are significantly increased in the T cell zone only, a change not seen by analyzing the whole spleen. Studying the spatial and temporal expression of genes will reveal new insights into the regulation of immune responses.     

Timing of IFN-beta exposure during human dendritic cell maturation and naive Th cell stimulation has contrasting effects on Th1 subset generation: a role for IFN-beta-mediated regulation of IL-12 family cytokines and IL-18 in naive Th cell differentiation

Type I IFNs, IFN-alpha and IFN-beta, are early effectors of innate immune responses against microbes that can also regulate subsequent adaptive immunity by promoting antimicrobial Th1-type responses. In contrast, the ability of IFN-beta to inhibit autoimmune Th1 responses is thought to account for some of the beneficial effects of IFN-beta therapy in the treatment of relapsing remitting multiple sclerosis. To understand the basis of the paradoxical effects of IFN-beta on the expression of Th1-type immune responses, we developed an in vitro model of monocyte-derived dendritic cell (DC)-dependent, human naive Th cell differentiation, in which one can observe both positive and negative effects of IFN-beta on the generation of Th1 cells. In this model we found that the timing of IFN-beta exposure determines whether IFN-beta will have a positive or a negative effect on naive Th cell differentiation into Th1 cells. Specifically, the presence of IFN-beta during TNF-alpha-induced DC maturation strongly augments the capacity of DC to promote the generation of IFN-gamma-secreting Th1 cells. In contrast, exposure to IFN-beta during mature DC-mediated primary stimulation of naive Th cells has the opposite effect, in that it inhibits Th1 cell polarization and promotes the generation of an IL-10-secreting T cell subset. Studies with blocking mAbs and recombinant cytokines indicate that the mechanism by which IFN-beta mediates these contrasting effects on Th1 cell generation is at least in part by differentially regulating DC expression of IL-12 family cytokines (IL-12 and/or IL-23, and IL-27) and IL-18.