Th1 and Th2 cytokines regulate proteoglycan-specific autoantibody isotypes and arthritis

BALB/c mice immunized with human cartilage proteoglycan (PG) develop arthritis accompanied by the production of autoantibodies to mouse cartilage PG. To determine whether the autoantibody isotype contributes to the onset and severity of arthritis, PG-specific serum IgG1 (Th2, IL-4-cytokine-supporting) and IgG2a (Th1, IFN-gamma-controlling) concentrations were monitored during immunization with PG in IL-4-deficient and IFN-gamma-deficient mice. Paradoxically, despite elevated IFN-gamma, the PG-specific IgG1 isotype was significantly higher than the PG-specific IgG2a response, and the PG-specific IgG1 isotype was independent of IL-4. In contrast, the serum concentration of PG-specific IgG2a isotype was six times higher in IL-4-deficient mice than in wild-type controls. Moreover, the high concentration of PG-specific IgG2a isotype in IL-4-deficient mice corresponded to an increased severity of arthritis. The concentration of PG-specific IgG2a isotype was lower in IFN-gamma-deficient mice than in wild-type mice, and the incidence and severity of arthritis also were significantly lower. Concentrations of PG-specific IgG2a isotype autoantibody correlated with the onset and severity of arthritis, suggesting a pathological role of this isotype, probably locally in the joint.     

Th1 and Th2 cytokines regulate proteoglycan-specific autoantibody isotypes and arthritis

BALB/c mice immunized with human cartilage proteoglycan (PG) develop arthritis accompanied by the production of autoantibodies to mouse cartilage PG. To determine whether the autoantibody isotype contributes to the onset and severity of arthritis, PG-specific serum IgG1 (Th2, IL-4-cytokine-supporting) and IgG2a (Th1, IFN-γ-controlling) concentrations were monitored during immunization with PG in IL-4-deficient and IFN-γ-deficient mice. Paradoxically, despite elevated IFN-γ, the PG-specific IgG1 isotype was significantly higher than the PG-specific IgG2a response, and the PG-specific IgG1 isotype was independent of IL-4. In contrast, the serum concentration of PG-specific IgG2a isotype was six times higher in IL-4-deficient mice than in wild-type controls. Moreover, the high concentration of PG-specific IgG2a isotype in IL-4-deficient mice corresponded to an increased severity of arthritis. The concentration of PG-specific IgG2a isotype was lower in IFN-γ-deficient mice than in wild-type mice, and the incidence and severity of arthritis also were significantly lower. Concentrations of PG-specific IgG2a isotype autoantibody correlated with the onset and severity of arthritis, suggesting a pathological role of this isotype, probably locally in the joint.     

Temporal expression patterns of distinct cytokines and M1/M2 macrophage polarization regulate rheumatoid arthritis progression

Molecular Biology Reports - Rheumatoid arthritis (RA) is an autoimmune disease characterized by chronic inflammation of synovial joints and often associated with chronic pain. Chronic joint...     

Hexosamines regulate sensitivity of glucose-stimulated insulin secretion in beta-cells

Hexosamines serve a nutrient-sensing function through enzymatic O-glycosylation of proteins. We previously characterized transgenic (Tg) mice with overexpression of the rate-limiting enzyme in hexosamine production, glutamine:fructose-6-phosphate amidotransferase, in beta-cells. Animals were hyperinsulinemic, resulting in peripheral insulin resistance. Glucose tolerance deteriorated with age, and males developed diabetes. We therefore examined islet function in these mice by perifusion in vitro. Young (2-mo-old) Tg animals had enhanced sensitivity to glucose of insulin secretion. Insulin secretion was maximal at 20 mM and half maximal at 9.9 +/- 0.5 mM glucose in Tg islets compared with maximal at 30 mM and half maximal at 13.5 +/- 0.7 mM glucose in wild type (WT; P < 0.005). Young Tg animals secreted more insulin in response to 20 mM glucose (Tg, 1,254 +/- 311; WT, 425 +/- 231 pg x islet(-1) x 35 min(-1); P < 0.01). Islets from older (8-mo-old) Tg mice became desensitized to glucose, with half-maximal secretion at 16.1 +/- 0.8 mM glucose, compared with 11.8 +/- 0.7 mM in WT (P < 0.05). Older Tg mice secreted less insulin in response to 20 mM glucose (Tg, 2,256 +/- 342; WT, 3,493 +/- 367 pg x islet(-1) x 35 min(-1); P < 0.05). Secretion in response to carbachol was similar in WT and Tg at both ages. Glucose oxidation was blunted in older Tg islets. At 5 mM glucose, islet CO2 production was comparable between Tg and WT. However, WT mice increased islet CO2 production 2.7 +/- 0.4-fold in 20 mM glucose, compared with only 1.4 +/- 0.1-fold in Tg (P < 0.02). Results demonstrate that hexosamines are involved in nutrient sensing for insulin secretion, acting at least in part by modulating glucose oxidation pathways. Prolonged excess hexosamine flux results in glucose desensitization and mimics glucose toxicity.     

Germinal centers regulate human Th2 development

In the present study we demonstrate that all CD4(+) T cells in human tonsil expressing the Th2-selective receptor chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2) also 1) express high levels of CXCR5, and 2) display a transitional CD45RA/RO phenotype and consistently do not produce significant amounts of cytokines when immediately analyzed ex vivo. Hence, they represent precursors of Th2 effector cells, a conclusion confirmed by their robust production of IL-4, IL-5, and IL-13, but not IFN-gamma, after in vitro activation. CD4(+) T cells, which express only intermediate levels of CXCR5, instead develop into IFN-gamma-producing cells under identical culture conditions, thus establishing a correlation between relative levels of CXCR5 expression and the acquired cytokine profile. Because CXCR5 is critically involved in follicular localization, the results suggest that these CRTH2(+) Th2 cells preferentially develop their cytokine-producing phenotype within germinal centers (GCs), whereas extrafollicular differentiation instead promotes Th1 development. In support for this proposal, we show that T cells with an intermediate expression of CXCR5 can be forced to also produce IL-4 and IL-13 if cultured with allogenic GC B cells. Finally, we demonstrate that the previously described CD57(+) GC T cells also express high levels of CXCR5 but instead of comprising a Th2 precursor, they represent anergized T cells. Taken together, these data suggest that GCs and B cells regulate CD4(+) T cell differentiation in a finely tuned fashion, either by promoting differentiation of Th2 cells, which apparently leave the lymphoid tissue before evolving a cytokine-producing phenotype, or by furnishing T cell unresponsiveness.     

Th2 cytokines in susceptibility to tuberculosis

We need to understand what is different about susceptibility to tuberculosis (TB) in developing countries where most TB occurs, and where the current vaccine, Bacillus Calmette et Guérin (BCG) usually fails to protect. The presence of a background mixed IFN-gamma and Th2 response to mycobacterial antigens before infection with M. tuberculosis (Mtb), and the development of a large IL-4 response during progressive TB, are characteristics of individuals in the locations where BCG fails, which are also seen in animal models in the same countries. Recent data suggest that the background Th1 component in developing countries protects from low dose challenge with Mtb in mouse and man, but that following high dose challenge the pre-existing IL-4 component increases and blocks immunity unless the individual's immune system releases IL-4delta2, an antagonist of IL-4, which is raised in the blood of donors with stable latent TB. We outline how IL-4 (and IL-13) can undermine Th1-mediated immunity and drive inappropriate alternative activation of macrophages. The mechanisms of the effects of IL-4 include impaired antimicrobial activity due to reduced TNF-alpha-mediated apoptosis of infected cells, reduced activity of iNOS, increased availability of iron to intracellular Mtb, and increased proliferation of antigen-specific FOXP-3+ regulatory T cells. IL-4 also increases the toxicity of TNF-alpha and drives pulmonary fibrosis, thus enhancing immunopathology. The conclusion is that a vaccine that will work in developing countries might need to do more than enhance the existing Th1 response. In these environments it might be more important to block the Th2 component.     

Regulation of insulin sensitivity by adipose tissue-derived hormones and inflammatory cytokines

PURPOSE OF REVIEW: The aim of this review is to assess the role of adipose tissue-derived hormones and inflammatory cytokines in the pathogenesis of obesity-linked type II diabetes, with a special focus on articles published between December 2002 and December 2003. RECENT FINDINGS: Insulin resistance is widely recognized as a fundamental defect seen in obesity and type II diabetes. Although the molecular mechanisms triggering the development of insulin resistance remain elusive, recent studies have suggested that adipose tissue and adipose tissue-derived hormones and inflammatory cytokines play essential roles in the overall insulin sensitivity in vivo. Dysfunctions of adipose tissue can lead to systemic insulin resistance. SUMMARY: Understanding the regulation of the metabolic and secretory functions of adipose tissue, as well as its subsequent impact on overall insulin sensitivity, is becoming increasingly important given the therapeutic potential of targeting the root causes of insulin resistance in the treatment of type 2 diabetes and its associated complications, such as cardiovascular and cerebrovascular diseases.     

Alternative M2 activation of Kupffer cells by PPARdelta ameliorates obesity-induced insulin resistance

Macrophage infiltration and activation in metabolic tissues underlie obesity-induced insulin resistance and type 2 diabetes. While inflammatory activation of resident hepatic macrophages potentiates insulin resistance, the functions of alternatively activated Kupffer cells in metabolic disease remain unknown. Here we show that in response to the Th2 cytokine interleukin-4 (IL-4), peroxisome proliferator-activated receptor delta (PPARdelta) directs expression of the alternative phenotype in Kupffer cells and adipose tissue macrophages of lean mice. However, adoptive transfer of PPARdelta(-/-) (Ppard(-/-)) bone marrow into wild-type mice diminishes alternative activation of hepatic macrophages, causing hepatic dysfunction and systemic insulin resistance. Suppression of hepatic oxidative metabolism is recapitulated by treatment of primary hepatocytes with conditioned medium from PPARdelta(-/-) macrophages, indicating direct involvement of Kupffer cells in liver lipid metabolism. Taken together, these data suggest an unexpected beneficial role for alternatively activated Kupffer cells in metabolic syndrome and type 2 diabetes.     

Cysteinyl leukotrienes regulate Th2 cell-dependent pulmonary inflammation

The Th2 cell-dependent inflammatory response is a central component of asthma, and the ways in which it is regulated is a critical question. The cysteinyl leukotrienes (cys-LTs) are 5-lipoxygenase pathway products implicated in asthma, in particular, by their function as smooth muscle constrictors of airways and microvasculature. To elucidate additional roles for cys-LTs in the pathobiology of pulmonary inflammation, we used an OVA sensitization and challenge protocol with mice lacking leukotriene C(4) synthase (LTC(4)S), the terminal enzyme for cys-LT generation. Ag-induced pulmonary inflammation, characterized by eosinophil infiltration, goblet cell hyperplasia with mucus hypersecretion, and accumulation and activation of intraepithelial mast cells was markedly reduced in LTC(4)S(null) mice. Furthermore, Ag-specific IgE and IgG1 in serum, Th2 cell cytokine mRNA expression in the lung, and airway hyperresponsiveness to methacholine were significantly reduced in LTC(4)S(null) mice compared with wild-type controls. Finally, the number of parabronchial lymph node cells from sensitized LTC(4)S(null) mice and their capacity to generate Th2 cell cytokines ex vivo after restimulation with Ag were also significantly reduced. In contrast, delayed-type cutaneous hypersensitivity, a prototypic Th1 cell-dependent response, was intact in LTC(4)S(null) mice. These findings provide direct evidence of a role for cys-LTs in regulating the initiation and/or amplification of Th2 cell-dependent pulmonary inflammation.     

MTHFD2 reprograms macrophage polarization by inhibiting PTEN

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Novel interactions of a microbial superantigen with TLR2 and TLR4 differentially regulate IL-17 and Th17-associated cytokines

Mycoplasma arthritidis, an inflammatory murine pathogen, secretes a potent superantigen, Mycoplasma arthritidis mitogen (MAM) that contributes to toxic shock, arthritis and skin necrosis. Previously we showed that MAM induced type 2 T-cell cytokines in mice that express functional TLR2 and TLR4, but type 1 cytokines in mice that lack TLR4 function. We show here that IL-17, pSTAT3 and retinoid-related orphan nuclear receptorγt are rapidly expressed in wild-type C3H/HeSnJ (TLR2+/4+) mice but are significantly delayed in mutant C3H/HeJ (TLR2+/4-) mice. This marked kinetic difference was associated with a high level of IL-6 in TLR2+/4+ mice versus high levels of IL-1β and TNFα in TLR2+/4- mice. Also antibodies to IL-6 and IL-23, suppressed IL-17 responses to MAM in TLR2+/4+ mice whereas anti-IL-1β, but not anti-TNFα, enhanced IL-17 in TLR2+/4- mice. Antibody blocking of TLR4 in TLR2+/4+ mice decreased IL-17 and IL-6 but not IL-23. In addition both IL-17 and IL-6 but not IL-23 were elevated in TLR2 KO mice versus wild-type TLR2+/4+ mice given MAM. We conclude that the MAM interaction with TLR2 versus TLR4 leads to distinct cytokine pathways mediated primarily by IL-1β or IL-6/IL-17 signalling respectively. Our findings suggest that the differential interaction of MAM with different TLRs might play an important role in disease outcomes by M. arthritidis.     

The role of Th1/Th2 polarization in mucosal immunity

Mucosal immunity relies on the delicate balance between antigen responsiveness and tolerance. The polarization of T helper cells plays a key role in maintaining or disrupting this equilibrium.     

Th2型细胞因子在支气管哮喘发作过程中的表达

支气管哮喘是由多种细胞特别是肥大细胞、嗜酸性粒细胞和T淋巴细胞参与的慢性气道炎症。对支气管哮喘发病机制的认识近年有重大改变 ,Th2型细胞的作用被认为是支气管哮喘发作过程的中心 ,综述了由Th2型细胞产生的细胞因子在支气管哮喘发病过程中的作用及意义。     

Age-related differentiations of Th1/Th2 cytokines in newborn infants

OBJECTIVE: To evaluate age-related differentiation of immune response in newborns by measuring serum concentrations of interleukin-2 (IL-2), interleukin-4 (IL-4) and interferon-gamma (IFN-gamma) during the perinatal period. SUBJECTS AND METHODS: Fifty-seven healthy term neonates, their mothers and 25 healthy adults (controls) age-matched to the mothers were included in the study. Cytokine concentrations were measured in the umbilical cord (UC), and in first-day (1N) and fifth-day (5N) neonatal samples, compared with those in maternal serum (MS) and control serum samples. RESULTS: Serum IL-2 concentrations in the UC were markedly elevated compared with those in MS and controls (p < 0.0001), decreasing significantly thereafter up to 5N (p < 0.001). IL-4 serum concentrations did not differ significantly between the UC, 1N and 5N samples; they were, however, markedly elevated compared with those in MS (p < 0.001, p < 0.0007 and p < 0.0001, respectively) and controls (p < 0.05, p < 0.01 and p < 0.006, respectively). IFN-gamma serum concentrations were significantly lower in the UC compared with those in controls (p < 0.04), increasing significantly up to 5N (p < 0.03). Both IFN-gamma/IL-2 and IFN-gamma/IL-4 ratios increased significantly in 5N, compared with those in the UC (p < 0.001 and p < 0.03). CONCLUSION: Our findings indicate a differential cytokine balance at birth with enhanced expression of IL-2 and IL-4 against IFN-gamma. However, a regularization of immune response seems to proceed quickly during the early neonatal life.     

微卡对支气管哮喘Th1/Th2类细胞因子失衡的调节作用

目的 探讨微卡对哮喘ThⅠ/Th2类细胞因子失衡的调节作用.方法 选取确诊的轻中度哮喘40例,所有患者深部肌肉注射微卡22.5μg,每2周1次,共8周,并在治疗前、治疗后1月、2月分别抽取静脉血3 ml检测IFN-γ和IL-4水平（ELISA法）.结果 微卡治疗后1月即可纠正失衡的IFN-γ/IL-4,其中以治疗后2月作用较明显,且未见明显的药物不良反应.结论 微卡通过调节失衡的Th1/Th2平衡而达到抗气道炎症作用,可作为哮喘的防治药物.     

CD2 facilitates differentiation of CD4 Th cells without affecting Th1/Th2 polarization.

The role of CD2 in murine CD4 helper T cell differentiation and polarization was examined using TCR-Cyt-5CC7-I transgenic recombination activating gene-2-/- H-2(a) mice on CD2+/+ or CD2-/- backgrounds. In the absence of CD2, thymic development was abnormal as judged by reduction in the steady state number of total, double-positive, and CD4 single-positive (SP) thymocytes, as well as a defect in their restorative dynamics after peptide-induced negative selection in vivo. In addition, in CD2-/- animals, lymph node CD4 SP T cells manifest a 10- to 100-fold attenuated activation response to cytochrome c (CytC) agonist peptides as judged by induction of CD25 and CD69 cell surface expression or [(3)H]TdR incorporation; differences in the magnitude of responsiveness and requisite molar peptide concentrations were even greater for altered peptide ligands. Although the presence or absence of CD2 did not impact the final Th1 or Th2 polarization outcome, CD2 expression reduced the CytC peptide concentration threshold necessary to facilitate both Th1 and Th2 differentiation. In vivo administration of CytC peptide to CD2-/- animals yielded an impaired CD4 SP T cell effector/memory phenotype compared with similarly treated CD2+/+ mice. Analysis of TCR-Cyt-5CC7-I human CD2 double-transgenic mice similarly failed to reveal a preferential Th1 vs Th2 polarization. Collectively, these results indicate that CD2 is important for the efficient development of CD4 SP thymocytes and TCR-dependent activation of mature CD4 lymph node T cells, but does not direct a particular helper T cell subset polarity.     

Th1 cytokines regulate adenosine receptors and their downstream signaling elements in human microvascular endothelial cells

We and others have shown that adenosine, acting at its receptors, is a potent modulator of inflammation and angiogenesis. To better understand the regulation of adenosine receptors during these processes we studied the effects of IL-1, TNF-alpha, and IFN-gamma on expression and function of adenosine receptors and select members of their coupling G proteins in human dermal microvascular endothelial cells (HMVEC). HMVEC expressed message and protein for A(2A) and A(2B), but not A(1) or A(3) receptors. IL-1 and TNF-alpha treatment increased message and protein expression of A(2A) and A(2B) receptor. IFN-gamma treatment also increased the expression of A(2B) receptors, but decreased expression of A(2A) receptors. Resting HMVEC and IFN-gamma-treated cells showed minimal cAMP response to the selective A(2A) receptor agonist 2-[2-(4-chlorophenyl)ethoxy]adenosine (MRE0094). In contrast, MRE0094 stimulated a dose-dependent increase in cAMP levels in TNF-alpha-treated cells that was almost completely blocked by the A(2A) receptor antagonist ZM-241385 (4-[2-[7-amino-2-(2-furyl)[1,2,4]triazolo-[2,3-a][1,3,5]triazin-5-ylamino]ethyl]phenol). The nonselective adenosine receptor agonist 5'-(N-ethylcarboxamido)adenosine increased cAMP levels in both TNF-alpha- and IFN-gamma-treated cells, but not control cells, and its effect was only partially reversed by ZM-241385 in TNF-alpha-treated cells and not affected in IFN-gamma-treated cells. HMVEC expressed a higher level of G protein beta1 isoform than beta4 isoform. Although none of the cytokines tested affected G(beta1) expression, both IL-1 and TNF-alpha significantly up-regulated G(beta4) expression. These findings indicate that inflammatory cytokines modulate adenosine receptor expression and function on HMVECs and suggest that the interaction between proinflammatory cytokines and adenosine receptors may affect therapeutic responses to anti-inflammatory drugs that act via adenosine-dependent mechanisms.