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Evolving T cell responses in murine schistosomiasis. Th2 cells mediate secondary granulomatous hypersensitivity and are regulated by CD8+ T cells in vivo.

The dynamics of T cell maturation and regulation were examined during the granulomatous response to Schistosoma mansoni eggs under conditions of primary (PRIM), secondary vigorous (VIG), and secondary immunomodulated (MOD) immunity. The patterns of VIG and MOD GR (GR) formation were established in naive CBA mice by transfer of lymphoid cells from S. mansoni-infected donors at the VIG and MOD stages of infection. Sequential production of IFN, IL-2, and IL-4 was assessed at the GR and in draining lymph nodes (LN) to determine the participation of Th1 (IFN-producing) and Th2 (IL-4/IL-5-producing) cells. The PRIM GR produced IFN in the growth phase (2-16 days) and IL-4 was detected only after lesions were established (16-24 days). The PRIM LN showed coincident production of IFN, IL-2, and IL-4 on day 4 followed by mainly IL-4 and IL-2 production on day 8, consistent with Th2 differentiation via a Th0 precursor. The VIG GR produced high levels of IL-4 in the growth phase (4-8 days) although IFN remained at modest levels. The VIG LN showed increased cytokine levels consistent with an anamnestic response and again the pattern suggested Th2 differentiation from Th0 cells. The MOD mice had abrogated GR IL-4 levels and arrested Th2 differentiation in LN. In vitro mix studies indicated that the impaired cytokine production was not due to direct suppression. The role of Ts cells was next explored by T cell subset depletion. Pan-T cell depletion of VIG cells profoundly abrogated IL-4 production although CD8+ cell depletion augmented GR area by 70% as well as local and regional IL-4 production by 100 to 150%. Similarly, CD8+ cell depletion of MOD cells augmented GR size and IL-4 production but the response was less than corresponding VIG mice, suggesting that Th activity was reduced in MOD mice. Transfer studies indicated that CD8+ cells inhibited Th2 maturation in LN. Thus, the schistosome egg GR demonstrated a Th1-like pattern in the PRIM response followed by a Th2 pattern in the VIG stage and abrogated Th2 activity in the MOD stage. Finally, the phenomenon of "spontaneous modulation" likely represents the cumulative action of CD8+ cells which steadily erode the Th population.

Animals↗

Th2-cell-mediated chemokine synthesis is involved in allergic airway inflammation in mice.

Eosinophilic inflammation in the bronchial mucosa has been recognized as a prominent pathological feature of bronchial asthma. Th2 cells have been implicated in the local infiltration and activation of eosinophils. The migration of eosinophils as well as Th2 cells is controlled by chemokines, suggesting a crucial role of chemokines in the pathogenesis of bronchial asthma. To elucidate the mechanism by which Th2 cells induce eosinophilic inflammation, a Th2-cell-dependent murine model of asthma was employed in this study. Along with the infiltration of eosinophils and antigen-specific Th2 cells, CC chemokine receptor-3-active eotaxin, monocyte chemoattractant protein (MCP)-3 and RANTES, as well as CC chemokine receptor-3-inactive MCP-1 were produced in the lungs of Th2-cell-transferred mice after antigen provocation in vivo. On the other hand, differentiated antigen-specific Th2 cells produced MCP-3 and RANTES but not eotaxin or MCP-1 upon stimulation in vitro. Chemokines synthesized by Th2 cells and other cell types are involved in the development of eosinophilic inflammation in bronchial asthma.

Animals↗

Dihydropyridine receptors are selective markers of Th2 cells and can be targeted to prevent Th2-dependent immunopathological disorders.

Th1 cells that produce IFN-gamma are essential in the elimination of intracellular pathogens, and Th2 cells that synthetize IL-4 control the eradication of helminths. However, highly polarized Th1 or Th2 responses may be harmful and even lethal. Thus, the development of strategies to selectively down-modulate Th1 or Th2 responses is of therapeutic importance. Herein, we demonstrate that dihydropyridine receptors (DHPR) are expressed on Th2 and not on Th1 murine cells. By using selective agonists and antagonists of DHPR, we show that DHPR are involved in TCR-dependent calcium response in Th2 cells as well as in IL-4, IL-5, and IL-10 synthesis. Nicardipine, an inhibitor of DHPR, is beneficial in experimental models of Th2-dependent pathologies in rats. It strongly inhibits the Th2-mediated autoimmune glomerulonephritis induced by injecting Brown Norway (BN) rats with heavy metals. This drug also prevents the chronic graft vs host reaction induced by injecting CD4(+) T cells from BN rats into (LEW x BN)F(1) hybrids. By contrast, treatment with nicardipine has no effect on the Th1-dependent experimental autoimmune encephalomyelitis triggered in LEW rats immunized with myelin. These data indicate that 1) DHPR are a selective marker of Th2 cells, 2) these calcium channels contribute to calcium signaling in Th2 cells, and 3) blockers of these channels are beneficial in the treatment of Th2-mediated pathologies.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗

Islet-specific Th1, but not Th2, cells secrete multiple chemokines and promote rapid induction of autoimmune diabetes.

Migration of CD4 cells into the pancreas represents a hallmark event in the development of insulin-dependent diabetes mellitus. Th1, but not Th2, cells are associated with pathogenesis leading to destruction of islet beta-cells and disease onset. Lymphocyte extravasation from blood into tissue is regulated by multiple adhesion receptor/counter-receptor pairs and chemokines. To identify events that regulate entry of CD4 cells into the pancreas, we transferred Th1 or Th2 cells induced in vitro from islet-specific TCR transgenic CD4 cells into immunodeficient (NOD.scid) recipients. Although both subsets infiltrated the pancreas and elicited multiple adhesion receptors (peripheral lymph node addressin, mucosal addressin cell adhesion molecule-1, LFA-1, ICAM-1, and VCAM-1) on vascular endothelium, entry/accumulation of Th1 cells was more rapid than that of Th2 cells, and only Th1 cells induced diabetes. In vitro, Th1 cells were also distinguished from Th2 cells by the capacity to synthesize several chemokines that included lymphotactin, monocyte chemoattractant protein-1 (MCP-1), and macrophage inflammatory protein-1alpha, whereas both subsets produced macrophage inflammatory protein-1beta. Some of these chemokines as well as RANTES, MCP-3, MCP-5, and cytokine-response gene-2 (CRG-2)/IFN-inducible protein-10 (IP-10) were associated with Th1, but not Th2, pancreatic infiltrates. The data demonstrate polarization of chemokine expression by Th1 vs Th2 cells, which, within the microenvironment of the pancreas, accounts for distinctive inflammatory infiltrates that determine whether insulin-producing beta-cells are protected or destroyed.

Animals↗

Microglia are more efficient than astrocytes in antigen processing and in Th1 but not Th2 cell activation.

Microglia and astrocytes, two glial cell populations of the central nervous system, present Ag and stimulate T cell proliferation, but it is unclear whether they preferentially activate Th1 or Th2 responses. We have investigated the efficiency of microglia and astrocytes in the presentation of OVA peptide 323-339 or native OVA to Th1 and Th2 cell lines from DO11.10 TCR transgenic mice. Upon stimulation with IFN-gamma, microglia express MHC class II molecules, CD40, and ICAM-1 and efficiently present OVA 323-339, leading to T cell proliferation and production of IL-2 and IFN-gamma by Th1 and of IL-4 by Th2 cells. IFN-gamma-treated astrocytes, which express MHC class II and ICAM-1, present OVA 323-339 less efficiently to Th1 cells but are as efficient as microglia in inducing IL-4 secretion by Th2 cells. However, astrocytes are much less potent than microglia in presenting naturally processed OVA peptide to either T cell subset, indicating inefficient Ag processing. The capacity of astrocytes and microglia to stimulate Th1 and Th2 cells depends on their MHC class II expression and does not involve ICAM-1, B7-1, or B7-2 molecules. However, CD40-CD40L interactions contribute to Th1 activation by microglia. These data suggest that microglia may play a role in the activation of Th1 and Th2 cells, whereas astrocytes would restimulate mainly Th2 responses in the presence of appropriate peptides. This differential capacity of brain APC to restimulate Th1 and Th2 responses may contribute to the reactivation and regulation of local inflammatory processes during infectious and autoimmune diseases.

Animals↗

Determination of intracellular cytokines produced by Th1 and Th2 cells using flow cytometry in patients with brucellosis.

The aim of the study was to evaluate intracellular interferon-gamma (IFN-gamma), and interleukin-4 (IL-4) levels in pre- and post-treatment periods of brucellosis patients and to determine the relationship between these parameters and patients' clinical findings. Twenty-five patients diagnosed as brucellosis and 11 aged-matched healthy volunteers were included in the study. CD3+CD4+ T lymphocytes levels were significantly lower in patients with brucellosis as compared to the control group. CD3+CD8+ T lymphocytes and CD3+IFN-gamma+ levels were increased in brucellosis patients compared with the control group. CD4+IFN-gamma+ and CD4+IL-4+ levels were no different between patients and healthy individuals. CD3+IL-4+ levels decreased in patients compared with healthy controls. Pre-treatment CD3+IFN-gamma+ levels dramatically increased in patients responsive to management compared with the unresponsive ones. In responsive cases, CD3+IFN-gamma+ levels decreased statistically after the treatment while in unresponsive cases no meaningful change was observed with respect to treatment. Adding IFN-gamma to the treatment for improving the depleted levels of IFN-gamma can be beneficial in patients with brucellosis who shows a tendency to chronicity or patients who do not respond to the treatment.

Adolescent↗

Sustained T-bet expression confers polarized human TH2 cells with TH1-like cytokine production and migratory capacities.

BACKGROUND: The transcription factor T-bet mediates IFN-gamma production by T(H)1 cells and suppresses T(H)2 cytokine production when ectopically expressed in polarized murine T(H)2 cells. Thus T-bet-mediated inhibition of T(H)2 cytokine production might be beneficial for the treatment of allergic diseases like asthma or atopic dermatitis. OBJECTIVE: We sought to investigate the effects of ectopic T-bet expression in highly polarized human T(H)2 cells obtained from skin biopsy specimens of patients with atopic dermatitis. METHODS: The cytokine production of T(H)2 cells retrovirally transfected with a vector expressing human T-bet was determined by means of intracellular FACS staining and ELISA. The effects of T-bet transfection were analyzed at the mRNA level by means of real-time PCR and DNA microarrays and confirmed by using functional chemokine response assays. RESULTS: Transfection of T-bet into T(H)2 cells induced high levels of IFN-gamma and suppressed IL-5, but IL-2 and IL-4 production remained unchanged. T-bet transfection also induced IL-12Rbeta2 and CXCR3 expression on human T(H)2 cells, whereas the IL-18 receptor was only induced as a consequence of T-bet-mediated increased responsiveness to IL-12. Furthermore, sustained T-bet expression in human T(H)2 cells induced IL-2 production and decreased the secretion of IL-4. In addition, the chemokine receptor repertoire of these cells was changed toward a T(H)1-like profile. CONCLUSION: The combined switch in cytokine pattern and migratory potential of highly polarized human T(H)2 cells mediated by T-bet might provide an additional advantage for the treatment of allergic diseases.

Cell Movement↗

Diesel exhaust exposure favors TH2 cell recruitment in nonatopic subjects by differentially regulating chemokine production.

BACKGROUND: The prevalence of allergic diseases has increased in the last 20 years, and a number of studies have shown that diesel exhaust particle-associated polyaromatic hydrocarbons can exacerbate the allergic reaction. Much less is known about their potential capacity to generate a T(H)2-type allergic reaction in nonatopic subjects. OBJECTIVE: The aim of this study was to test the hypothesis that diesel exhaust exposure might favor, in nonatopic donors, T(H)2-type cell recruitment, either through increased production of T(H)2-attracting chemokines or decreased production of T(H)1-attracting chemokines. METHODS: PBMCs from nonatopic donors were incubated with diesel exhaust particle-polyaromatic hydrocarbons, and the supernatants were evaluated for the presence of pro-T(H)1 chemokines (IFN-gamma-induced protein 10 and monokine Induced by IFN-gamma) and pro-T(H)2 chemokines (macrophage-derived chemokine, I-309, and pulmonary and activation-regulated chemokine) by means of ELISA. The functional effect was evaluated by using chemotaxis assays with polarized T(H)1 and T(H)2 cells. RESULTS: Diesel exhaust exposure of PBMCs from nonatopic donors induced a late increase after 48 hours in pulmonary and activation-regulated chemokine mediated by IL-13 and a decrease in IFN-gamma-induced protein 10 levels selectively at both the protein and mRNA levels. The functional effect of these chemokine variations resulted in an enhanced chemotaxis of T(H)2, but not T(H)1, cells. CONCLUSION: These findings show that diesel exhaust exposure might be involved in the genesis of allergic diseases by differentially regulating chemokines favoring the recruitment of T(H)2 cells in nonatopic subjects. CLINICAL IMPLICATIONS: Environmental factors, especially air pollution, might favor the genesis of allergic diseases.

Adult↗

Hyperresponsive TH2 cells with enhanced nuclear factor-kappa B activation induce atopic dermatitis-like skin lesions in Nishiki-nezumi Cinnamon/Nagoya mice.

BACKGROUND: Nishiki-nezumi Cinnamon/Nagoya (NC/Nga) mice raised in nonair-controlled conventional circumstances spontaneously develop atopic dermatitis-like skin lesions; however, the underlying mechanisms remain unclear. OBJECTIVE: We wanted to identify the critical intracellular signaling molecules in T cells that induce atopic dermatitis-like skin legions in NC/Nga mice. METHODS: We examined the levels of signal transduction and cytokine production in T cells, particularly those in atopic dermatitis-like lesions induced by the topical injection of mite antigens in NC/Nga mice under specific pathogen-free conditions. RESULTS: In NC/Nga mice maintained under specific pathogen-free conditions, the capability of T(H)1/T(H)2 and T cytotoxic 1/T cytotoxic 2 (Tc1/Tc2) cell differentiation increased significantly. T-cell antigen receptor-mediated activation of the extracellular signal-regulated kinase/mitogen-activated protein kinase cascade and nuclear factor-kappaB (NF-kappaB) signaling were enhanced in NC/Nga T cells. The expression of T(H)2 cytokines (IL-4, IL-13, and IL-5) and that of GATA-binding protein 3 (GATA3), avian musculoaponeurotic fibrosarcoma (c-Maf), NF-kappaB, and activator protein 1 (AP1) selectively increased in draining lymph node T cells of NC/Nga mice. Moreover, the cell transfer of inhibitory NF-kappaB mutant-infected T(H)2 cells reduced ear thickness in the mite antigen-induced skin lesion of NC/Nga mice. CONCLUSION: Hyperresponsive T(H)2 cells with an enhanced activity of NF-kappaB and AP1 play a crucial role in the pathogenesis of atopic dermatitis-like skin lesions in NC/Nga mice. CLINICAL IMPLICATIONS: These results indicate potential therapeutic usefulness of developing selective inhibitors for NF-kappaB in the treatment of human atopic dermatitis.

Animals↗

Th1 and Th2 cells.

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Animals↗