Th2 Direction Research Articles

Impact of Adipose-Derived Mesenchymal Stem Cells (ASCs) of Rheumatic Disease Patients on T Helper Cell Differentiation.

Complex pathogenesis of systemic lupus erythematosus (SLE) and systemic sclerosis (SSc) is associated with an imbalance of various Th-cell subpopulations. Mesenchymal stem cells (MSCs) have the ability to restore this balance. However, bone marrow-derived MSCs of SLE and SSc patients exhibit many abnormalities, whereas the properties of adipose derived mesenchymal stem cells (ASCS) are much less known. Therefore, we examined the effect of ASCs obtained from SLE (SLE/ASCs) and SSc (SSc/ASCs) patients on Th subset differentiation, using cells from healthy donors (HD/ASCs) as controls. ASCs were co-cultured with activated CD4+ T cells or peripheral blood mononuclear cells. Expression of transcription factors defining Th1, Th2, Th17, and regulatory T cell (Tregs) subsets, i.e., T-bet, GATA3, RORc, and FoxP3, were analysed by quantitative RT-PCR, the concentrations of subset-specific cytokines were measured by ELISA, and Tregs formation by flow cytometry. Compared with HD/ASCs, SLE/ASCs and especially SSc/ASCs triggered Th differentiation which was disturbed at the transcription levels of genes encoding Th1- and Tregs-related transcription factors. However, we failed to find functional consequences of this abnormality, because all tested ASCs similarly switched differentiation from Th1 to Th2 direction with accompanying IFNγ/IL-4 ratio decrease, up-regulated Th17 formation and IL-17 secretion, and up-regulated classical Tregs generation.

CD4+CD25+ Tregs as dependent factor in the course of bleomycin-induced pulmonary fibrosis in mice

The immune system is felt to play an essential role in pulmonary fibrosis (PF). CD4+CD25+ regulatory T cells (Tregs) are crucial in maintaining immune tolerance and immune homeostasis, but their role in the pathogenesis of PF is controversial and still unclear. We here explored the relationship between peripheral blood CD4+CD25+ Tregs and the course of bleomycin-induced PF in mice. Mouse PF models were established by intratracheal instillation of bleomycin. Lung histology, hydroxyproline, Th1/Th2 balanc, CD4+CD25+ Tregse were analyzed at the 3rd，7th，14th，21st and 28th days after instillation. CD4+CD25+ Tregs were also transferred into mice with or without PF by tail vein injection. The trend of CD4+CD25+ Tregs changes was increased firstly, decreased, increased again from 7th to 28th days after bleomycin instillation, which had great relevance with alveolitis and fibrosis scores. There also were high Th1 polarization index from 3rd to 14th days and high Th2 polarization index at 21st and 28th days after bleomycin treatment. CD4+CD25+ Tregs could promote the secretion of Th2 cytokines and inhibit the secretion of Th1 cytokines, allow the Th1/Th2 balance to Th2 direction in PF. Moreover, preventive adoptive transfer of CD4+CD25+ Tregs may ameliorate the process of PF, while acute adoptive transfer of CD4+CD25+ Tregs may aggravate the process of PF. These findings suggested that the dynamic changes of CD4+CD25+ Tregs as dependent factor might designate a different course of PF induced by bleomycin in mice, and might be a selected drug use indicator for therapy of PF.

Endocrine Factors Determining Immune Polarization during Perinatal Transition.

In utero the skewness of the adaptive immune system towards Th2 ('antiinflammatory') direction and low of Th1/Th2 cell ratio defend the fetus against rejection by the maternal immune system. Th2 dominance at birth is also of importance as it prevents uncontrolled inflammatory processes during parturition. This condition should change rapidly after birth. In an extrauterine milieu that is inherent with exposure to microorganisms, Th1 ('proinflammatory') polarization (i. e. increased Th1 cytokine production along with high Th1/Th2 ratio) are required to maintain an efficient immune response. After birth, maternal hormone supplies including estrogen, progesterone, testosterone, and antiinflammatory prostaglandins cease abruptly. As these hormones have an immune modulatory action favoring Th2, and inhibiting Th1 polarization, their low level supports the strengthening of Th1-type immunity. During parturition a dramatic but transient increase of several hormones (oxytocin, thyorid hormones, and catecholamines) occurs. Again, the net effect of high hormone levels favors Th2 activation, followed by Th1 polarization when hormonal levels reach their postnatal levels. The perinatal change of these components results in the quick cessation of Th1 inhibition and supports the maturation of adaptive immunity to provide an effective response against extrauterine microorganisms.

Transcutaneous immunization in auricle skin induces antigen-specific mucosal and systemic immune responses in BALB/c mice

ObjectiveTranscutaneous immunization (TCI) is a novel route of vaccination through application of a topical vaccine antigen on skin. Phosphorylcholine (PC) is a structural component of a variety of pathogens, and anti-PC immune responses protect mice against invasive bacterial diseases. The purpose of the study was to examine the effect of TCI using PC in back skin or auricle skin in BALB/c mice. MethodsTCI was performed in BALB/c mice in back skin or auricle skin using PC-keyhole limpet hemocyanin (KLH) plus cholera toxin (CT). Inoculations were given once each week for six consecutive weeks. Immunogenicity was evaluated by measuring PC-specific IgG and specific IgG1, IgG2a, IgM, IgA, and secretory IgA antibodies by ELISA. IL-4, IL-5, IL-10, IL-12, IL-13 and IFN-γ levels were also measured by ELISA. ResultsSerum IgG after TCI in auricle skin was significantly higher than after TCI in back skin and in controls. Secretory IgA antibodies after TCI in auricle skin were also significantly higher than after TCI in back skin and in controls in nasal, BALF, vaginal and fecal samples. PC-specific IgG1 and IgG2a were significantly higher after TCI in auricle skin compared to controls and compared to TCI in back skin. IgG1 was significantly higher than IgG2a after TCI in auricle skin. Production of IFN-γ, IL-4 and IL-10 from CD4+ cells was significantly higher after TCI in auricle skin than after TCI in back skin and in controls, whereas IL-5, IL-12 and IL-13 were not detected in any mice. ConclusionThese results suggest that TCI in auricle skin using PC plus CT in BALB/c mice is a simple approach for induction of systemic and mucosal immune responses that are shifted in the Th2 direction.

Transcutaneous immunization with phosphorylcholine induces antigen-specific mucosal and systemic immune responses in BALB/c mice.

Transcutaneous immunization (TCI) is a novel route of vaccination through application of a topical vaccine antigen on the skin. Phosphorylcholine (PC) is a structural component of a variety of pathogens and anti-PC immune responses protect mice against invasive bacterial diseases. The purpose of the study was to examine the effect of TCI using PC in BALB/c mice. TCI was performed in BALB/c mice using PC-keyhole limpet hemocyanin (KLH) plus cholera toxin (CT). Immunogenicity was evaluated by measuring PC-specific IgG and specific IgG1, IgG2a, IgM, IgA, and secretory IgA antibodies by ELISA. The concentrations of IL-4, IL-5, IL-10, IL-12, IL-13 and IFN-γ were also measured using ELISA for mouse. Six months after immunization, IgG after TCI using PC plus CT was significantly higher than in controls, but this was not found for IgA. In saliva, secretory IgA antibodies decreased with a peak level at 2-3 months. IgG1 was significantly higher than IgG2 after TCI. Production of IL-4 from CD4(+) cells was significantly higher after TCI than in controls, whereas production of IFN-γ, IL-5, IL-12 and IL-13 was not detected in either group. These results suggest that TCI using PC plus CT with BALB/c mice is a simple approach for induction of systemic and mucosal immune responses that are shifted in the Th-2 direction.

Thymic stromal lymphopoietin downregulates filaggrin expression by signal transducer and activator of transcription 3 (STAT3) and extracellular signal-regulated kinase (ERK) phosphorylation in keratinocytes

Thymic stromal lymphopoietin downregulates filaggrin expression by signal transducer and activator of transcription 3 (STAT3) and extracellular signal-regulated kinase (ERK) phosphorylation in keratinocytes

Diverse T-cell responses characterize the different manifestations of cutaneous graft-versus-host disease

AbstractGraft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic stem cell transplantation (HCT) and can present in an acute (aGVHD), a chronic lichenoid (clGVHD), and a chronic sclerotic form (csGVHD). It is unclear whether similar or different pathomechanisms lead to these distinct clinical presentations. To address this issue, we collected lesional skin biopsies from aGVHD (n = 25), clGVHD (n = 17), and csGVHD (n = 7) patients as well as serial nonlesional biopsies from HCT recipients (prior to or post-HCT) (n = 14) and subjected them to phenotypic and functional analyses. Our results revealed striking differences between aGVHD and clGVHD. In aGVHD, we found a clear predominance of T helper (Th)2 cytokines/chemokines and, surprisingly, of interleukin (IL)-22 messenger RNA as well as an increase of IL-22–producing CD4+ T cells. Thymic stromal lymphopoietin, a cytokine skewing the immune response toward a Th2 direction, was elevated at day 20 to 30 post-HCT in the skin of patients who later developed aGVHD. In sharp contrast to aGVHD, the immune response occurring in clGVHD showed a mixed Th1/Th17 signature with upregulated Th1/Th17 cytokine/chemokine transcripts and elevated numbers of interferon-γ– and IL-17–producing CD8+ T cells. Our findings shed new light on the T-cell responses involved in the different manifestations of cutaneous GVHD and identify molecular signatures indicating the development of the disease.

Diverse T Cell Responses Lead To The Different Manifestations Of Cutaneous Graft-Versus-Host Disease

Graft-versus-host disease (GVHD) is a major complication of allogeneic hematopoietic stem cell transplantation (HCT). GVHD is classified into an acute (aGVHD) and a chronic form (cGVHD) based on NIH-defined, clinical criteria. In skin, aGVHD presents as a maculopapular rash, while cGVHD shows at the beginning the signs of lichenoid tissue inflammation (chronic inflammatory GVHD, ciGVHD) and, later, exhibits scleroderma-like features (chronic sclerotic GVHD, csGVHD). Mechanisms involved in the initiation and propagation of the different forms of GVHD are a main focus of HCT research, but remain controversially discussed. Acute GVHD has long been thought to mainly involve a type 1 T cell response, but more recent data have shown an involvement of Th2, Th17 and Treg cells. These T cell subsets, and particularly an altered regulatory T cell homeostasis, have also been reported to play a role in chronic GVHD, the pathogenesis of which is much less understood. Taken together, it is unclear which exact mechanisms are operative in the T cell immunopathogenesis of cutaneous GVHD. In this study, we searched for cellular and molecular patterns that would allow us to distinguish between the different forms of cutaneous GVHD and to draw conclusions about the pathomechanisms involved. To address this issue, we collected lesional skin biopsies from patients diagnosed with aGVHD (n=25), ciGVHD (n=17) and csGVHD (n=7). Clinical grading of acute and chronic GVHD was performed according to the modified Glucksberg criteria and the NIH consensus criteria, respectively. 14 HCT recipients underwent serial skin biopsies at different time points prior/after HCT (prior/after conditioning, day 20-30 post-HCT, day 100-120 post-HCT). Skin biopsies obtained were subjected to phenotypic and functional analyses. The cellular infiltrate was assessed by immunofluorescence stainings; interleukins and chemokines were measured by real-time RT-PCR. Cytokine secretion profiles of stimulated T cells from collagenase-digested GVHD skin biopsies were analyzed by intracellular flow cytometry. While CD4+ and CD8+ T cells dominated the inflammatory infiltrate in both acute and chronic GVHD skin lesions, the analysis of the quality of the T cell-mediated immune response revealed striking differences. In acute cutaneous GVHD, we found a “Th2 signature” as evidenced by highly increased transcripts of Th2 cytokines (IL-4, IL-5 and IL-13) and chemokines (CCL17, CCL20). Surprisingly, we also observed a strong up-regulation of IL-22, but not IL-17 mRNA, which was paralleled by an increase of IL-22-single-producing CD4+ T cells. IL-17/IL-22 double-positive T cells were almost absent. In sharp contrast to aGVHD, the immune response occurring in ciGVHD showed a mixed Th1/Th17 signature. This was evidenced by an up-regulation of Th1/Th17 cytokine (IFN-γ, IL-12/IL-23p40 and IL23p19) and chemokine transcripts (CCL5, CCR5, CXCL9, CXCL10). In accordance with this finding, increased numbers of IFN-ү- and IL-17-single-producing CD8+ T cells infiltrated ciGVHD skin lesions.Chronic sclerotic GVHD exhibited distinct features, including an abundance of mast cells and a down-regulation of T cell cytokines and chemokines relative to normal skin. In an attempt to identify a factor predicting the occurrence of acute cutaneous GVHD, we analyzed the cellular and molecular signatures in skin of HCT recipients before GVHD onset. In accordance with the finding of a Th2 response occurring in aGVHD, levels of TSLP, a keratinocyte-derived cytokine skewing the immune response towards a Th2 direction, were increased at day 20 after HCT in non-lesional skin of patients who would later develop aGVHD. In conclusion, the present study provides new insights into the diverse pathomechanisms operative in the acute and chronic form of cutaneous GVHD, respectively. Our findings allow to more accurately distinguish aGVHD from ciGVHD based on different cellular and molecular patterns. The analysis of TSLP expression in skin (before disease onset) could be helpful in identifying HCT recipients at risk for developing acute cutaneous GVHD. Disclosures: No relevant conflicts of interest to declare.

Effect of neonatal immunization with different dosage allergen on the immunity of mice when grown up

To study the effect of neonatal immunization with different dosage allergen on the immunity of mice when grown. Fifty neonatal BALB/c mice were divided into 4 groups randomly and subcutaneous injected with different dosage of ovalbumin (OVA) on day 1, 8 and 15 after born [NS group(10): injected with saline alone; NS + AL group (10): injected with saline and AL(OH)3; small dosage (SD) group (15): injected with 10 microg OVA and AL(OH)3; large dosage (LD) group (15): injected with 1000 microg OVA and AL(OH)3]. The mice were then challenged using caudal vein injection on 5 weeks old (NS group and NS + AL group were challenged with saline, SD group and LD group were challenged with 100 microg OVA). The blood was collected 1 week later to examine OVA specific IgE, IgG1 and IgG2a. Mononuclear cells were drawn from the spleen and cultured. Concentration of IL-4, IFN-r, IL-10 was examined in the cultural supernatant. Flow cytometry was used to test the expression of CD4+ IL-4+, CD4+ IFN-gamma+, CD4 IL-10 cells. It was found that concentration of OVA specific IgE (OVA-sIgE) in SD group (0.33 +/- 0.18) was significantly higher than that of NS (0.07 +/- 0.01) and NS + AL (0.09 +/- 0.04) group (t value was -3.46 and -3.21, all P < 0.01), and LD group (0.17 +/- 0.10) as well (t = 2.58, P < 0.05). The concentration of OVA-sIgE was higher in LD group than that of NS group (t = -2.53, P < 0.05), but similar with that of NS + AL group (t = -2.04, P > 0.05). Both the concentration of OVA-sIgG1 and sIgG2a was higher in SD and LD group than that of NS and NS + AL group (all P < 0.05). The concentration of IL-4, IFN-gamma and IL-10 in the cultural supernatant of spleen mononuclear was all higher in SD group than that of NS and NS + AL group (all P < 0.01). The ratio of IFN-gamma/IL-4 was significantly lower in SD group than that of NS and NS + AL group (t value was 2.14, 3.44, all P < 0.05), while the same ratio was higher in LD group than that of NS and NS + AL group (t value was -2.14, -1.61, all P < 0.05). Ratio of CD4+ IL-4+ cells was significant lower in LD group than that of SD group (P < 0.05), while it was not different with that of NS and NS + AL group (P > 0. 05). Neonatal immunization with low dosage OVA could generate a specific immunity with Th2 direction, while with large dosage OVA could generate a specific immunity with Th1 direction.

Effect of millimeter waves and cyclophosphamide on cytokine regulation

We have reported previously that millimeter waves (MMWs) protect T-cell functions from the toxic side effects of cyclophosphamide (CPA), an anticancer drug. Since the effect of MMWs has been reported to be mediated by endogenous opioids, the present study was undertaken to investigate the role of endogenous opioids in protection of T-cell functions by MMWs. The effect of MMWs (42.2 GHz, incident power density = 38 mW/cm2) was studied on CPA-induced suppression of cytokine release by T cells in the presence of selective opioid receptor antagonists (ORA). Production of cytokines was measured in CD4 T cells isolated from splenocytes. Treatment of mice with CPA suppressed the formation of Th1 cytokines (TNF-α, IFN-γ, and IL-2), shifting the overall balance toward Th2 (IL-4 and IL-5). MMW irradiation of CPA-treated groups up-regulated the production of Th1 cytokines suppressed by CPA. Treatment of the CPA+MMW group with selective kappa (κ) ORA further potentiated this effect of MMWs on Th1 cytokine production, whereas treatment with μ or δ ORA increased the imbalance of cytokine production in the Th2 direction. These results provide further evidence that endogenous opioids are involved in immunomodulation by MMWs.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

Regulatory T Cells and T Helper Subsets in Breast‐fed Infants With Hematochezia Caused by Allergic Colitis

The objective of our study was to investigate the prevalence of CD4 T lymphocyte subsets and their commitment to TH1 or TH2 direction in 10 infants with allergic colitis (AC) and 10 healthy controls. Infants with AC presented with a higher ratio of naïve to memory cells, lower prevalence of activated CD4CD25 cells and FoxP3 regulatory cells, and a shift to TH2 direction in balance compared with controls. These alterations are normalized upon cessation of AC symptoms on elemental L-amino acid formula. These findings suggest the importance of antigen exposure in AC in infancy.

Impaired T-Lymphocyte Subpopulations and Deranged Profile of Immunologic Activation in Patients with Gaucher Disease Type I

Patients with Gaucher disease exhibit substantial evidence of impairment of their immune system, namely, increased serum levels of proinflammatory cytokines and immunoglobulins, and increased incidence of B-cell malignancies, such as non-Hodgkin's lymphoma, MGUS and multiple myeloma. We investigated peripheral blood T-lymphocyte subpopulations with dual color flow cytometry, as well as the direction of T-lymphocyte activation, by using intracytoplasmic immunostaining for IL-2, IL-4, IL-10 and IFN-gamma, on resting CD4+ and CD8+ T-lymphocytes and following activation with PMA- 1 with the presence of Brefeldin-A. Evaluations were performed on 16 patients with type I Gaucher disease and on 17 healthy controls. Patients had significantly decreased absolute lymphocyte count (1621±684 vs 2148±566/mm3, p=0.013), CD3+ (1197±478 vs 1508±431/mm3, p=0.045) and CD4+ T-lymphocytes (658±245 vs 945±253/mm3, p=0.021), but not CD8+ T-lymphocytes (491±331 vs 486±189/mm3, p: n.s.), resulting in a significant reduction of the CD4/CD8 ratio (1.59±0.68 vs 2.16±0.83, p=0.041). The populations of naive CD4+CD45RA+ and of memory CD4+CD45RO+ T-lymphocytes were also significantly decreased (218±128 vs 432±179/mm3, p=0.0005 and 484±185 vs 631±231/mm3, p=0.056 respectively), however, CD8+CD45RA+ and CD8+CD45RO+ subpopulations did nor differ significantly, when compared to controls. CD3−CD56+, but not CD3+CD56+ lymphocytes were also decreased (131±82 vs 199±97/mm3, p=0.037). Patients had higher percentages of CD8+ (29.2±9.7 vs 23.5±6.8%, p=0.042), CD8+CD45RA+ (22.1±6.2 vs 18.3±5.0%, p=0.046) and CD8+CD45RO+ T-lymphocytes (13.2±6.2 vs 9.6±3.7%, p=0.027), as well as of activated CD8+HLA-DR+ (0.93±0.68 vs 0.48±0.21%, p=0.008) and CD4+HLA-DR+ T-lymphocytes (1.77±0.93 vs 1.09±0.48%, p=0.008). Moreover, although both, the absolute number and the percentage of CD20+ B-lymphocytes were similar, patients exhibited significantly increased absolute number and percentage of CD5+CD20+ B-lymphocytes (1.63±0.55 vs 0.64±0.37% p=0.00002 and 29±20 vs 13±8/mm3, p=0.011, respectively). Finally, patients with Gaucher disease had significantly increased resting TH2-polarized CD4+T-lymphocytes (CD4+IL-10+: 0.41±0.29 vs 0.24±0.11%, p=0.045) and TH1-polarized CD8+ T-lymphocytes (CD8+IFNγ+: 0.15±0.07 vs 0.08±0.04%, p=0.005, CD8+IL10+: 0.22±0.08 vs 0.32±0.014, p=0.052, and IFNγ+/IL4+ ratio among the CD8+ population 2.54±2.1 vs 1.08±0.91, p=0.018). Following mitogenic activation a very significant impairment of obtaining the TH1 phenotype was observed (CD4+IL2+ lymphocytes 33.7±17.1 vs 65.4±6.1%, p<0.00001). The above findings suggest that in patients with Gaucher disease there is a significant numerical impairment of T-helper lymphocytes and a shift towards TH-2 direction of lymphocyte activation. These findings may explain the rarity of autoimmune manifestations despite the chronic inflammatory reaction, as well as the increased incidence of lymphoid malignancies, which has been reported among patients suffering from this disease.

Atopic dermatitis: Therapeutic concepts evolving from new pathophysiologic insights

Recent insights into the relevance of the epidermal barrier function and its interaction with components of the innate and adaptive immune responses in patients with atopic dermatitis (AD) give rise to a number of novel potential treatment options. In particular, the identification of loss-of-function mutations in the barrier protein filaggrin and of a diminished expression of certain antimicrobial peptides in AD skin stimulates new concepts to think beyond the T(H)1/T(H)2 paradigm. This review will focus on these most recent discoveries and will discuss new and corresponding proof-of-concept trials in patients with AD. It will further speculate on novel ways to restore the homeostasis among the 3 major components in AD skin suspected to be clinically relevant.

Dendritic cell expression of the Notch ligand jagged2 is not essential for Th2 response induction in vivo

We have addressed the hypothesis that Notch ligands play a decisive role in determining the ability of antigen-presenting cells to influence T cell polarization. Dendritic cells displayed distinct expression profiles of Delta and Jagged ligands for Notch when exposed to biologically relevant pathogen preparations associated with Th1 or Th2 responses. Expression of delta4 was increased, and jagged2 decreased, after dendritic cell exposure to the Th1-promoting bacterium Propionibacterium acnes. In contrast, soluble egg antigen (SEA) from the parasitic helminth Schistosoma mansoni, a potent Th2 inducer, failed to significantly alter dendritic cell expression of any of the Notch ligands measured. Irrespective of this, jagged2-deficient dendritic cells were severely impaired in their ability to instruct Th2 polarization of naive T cells in vitro. However, the ability of SEA-pulsed jagged2-deficient dendritic cells to induce a Th2 response in vivo was unimpaired relative to jagged2-sufficient dendritic cells. Further, jagged2-deficient dendritic cells activated by P. acnes exhibited no evidence of enhanced (or impaired) Th1 induction in vivo. These data suggest that, although involved in Th2 direction in vitro, jagged2 is not fundamentally required for Th2 induction by SEA-activated dendritic cells in vivo.

Interleukin-4 Inhibits Caspase-3 by Regulating Several Proteins in the Fas Pathway during Initial Stages of Human T Helper 2 Cell Differentiation

Interleukin-4 (IL-4) is the main cytokine that polarizes activated naïve CD4+ T cells in the T helper 2 (Th2) direction. IL-4 also regulates the subsequent stages of Th2 cell-mediated diseases, such as allergies. We conducted a proteomics study to identify IL-4-induced differences during the initial stages of T helper cell differentiation. Primary CD4+ T lymphocytes were isolated from human cord blood, activated through CD3 and CD28, and cultured in the presence or absence of IL-4. Soluble proteins were separated by two-dimensional electrophoresis and visualized by staining with autoradiography, which indicated that at least 20 proteins might be regulated by IL-4. From this minimum of 20 stained proteins, altogether 35 proteins were identified using tandem mass spectrometry. Interestingly the fragmented form of GDP dissociation inhibitor expressed in lymphocytes/Rho GDP dissociation inhibitor 2 (Ly-GDI), a known target of Caspase-3, was observed to be down-regulated in IL-4-treated cells. It was shown in further studies that IL-4 decreases Caspase-3 activity and cell death in these cells. Neutralizing Fas-Fas ligand interaction led to decreased Caspase-3 activity and lowered Ly-GDI fragmentation. We further characterized the effects of IL-4 on the expression of main regulators in the Fas-mediated pathway. We demonstrated that IL-4 decreases expression of Fas receptor and increases expression of Bid, Bcl-2, and Bcl-xL. Importantly IL-4 significantly up-regulated the short form of c-FLIP, although the levels of c-FLIP long were unaltered after IL-4 induction. Taken together, our results indicate that IL-4 inhibits caspase activity during the initial stages of human Th2 cell differentiation by regulating expression of several key players in the Fas-induced pathway.

Predicting the course of asthma

Asthma is a complex genetic disease that is thought to result from a combination of genetic susceptibility and environmental exposures. Asthma most often develops within the first few years of life and identified risk factors include familial history of asthma, infantile atopic dermatitis, and skin test reactivity to a subgroup of allergens. It still is not clear whether the association with skin test reactivity reveals contributions to pathogenesis by enhanced tendency to produce IgE antibodies or enhanced tendency for T cells to polarize in a Th2 direction or whether these attributes simply act as markers of a condition the origins of which still have not been identified. Currently, severity and persistence have not been unequivocally linked to these (or other) factors. Although clinical remittance is common, recent studies suggest lung function deficits may persist in the absence of symptoms and contribute to risk for chronic obstructive pulmonary disease. Additional studies are needed to establish the mechanisms underlying the development of asthma so that preventive and cure modalities may be rationally developed.

The p38 mitogen‐activated protein kinase regulates effector functions of primary human CD4 T cells

The role of p38 mitogen-activated protein kinase in primary human T cells is incompletely understood. We analyzed in detail the role of p38 in the regulation of effector functions and differentiation of human CD4 T cells by using a p38-specific inhibitor and a dominant-negative mutant of p38. p38 was found to mediate expression of IL-10 and the Th2 cytokines IL-4, IL-5, and IL-13 in both, primary naive and memory T cells. In contrast, inhibition of p38 activity did not affect expression of the Th1 cytokines IFN-gamma and TNF induced by TCR-stimulation, but decreased IL-12-mediated IFN-gamma expression. Cytokine expression from established Th2 effector cells was also regulated by p38, however, the role of p38 was less pronounced compared to primary CD4 T cells. p38 MAPK regulated cytokine gene expression at both, the transcriptional level by activating gene transcription and the post-transcriptional level by stabilizing cytokine mRNA. As a result of the effect of p38 on IL-4 expression, p38 activity modulated differentiation of naive precursor T cells by inducing a shift of the Th1/Th2 balance toward the immuno-modulatory Th2 direction. Together, the data suggest that p38 plays a key role in human Th2 cell immune responses.

Efficient migration of dendritic cells toward lymph node chemokines and induction of TH1 responses require maturation stimulus and apoptotic cell interaction

AbstractDendritic cells (DCs) have the unique ability to initiate primary immune responses, and they can be conditioned for vaccinal purposes to present antigens after the engulfment of apoptotic cells. To recruit the rare antigen-specific naive T cells, DCs require a maturation step and subsequent transport toward lymph node (LN). To date, prostaglandin E2 (PGE2) is the best-characterized compound inducing this LN-directed migration in vitro, but PGE2 may skew the immune responses in a TH2 direction. We demonstrate here that on incubation with apoptotic tumor cells and tumor necrosis factor-α (TNF-α) or lipopolysaccharide (LPS), human monocyte-derived DCs become fully mature and acquire high migratory capacities toward LN-directing chemokines. The migration of TNF-α-treated DCs occurs only after cotreatment with apoptotic cells but not with necrotic cells. DC migration requires CD36 expression and incubation with apoptotic cells in the presence of heat-labile serum components. Moreover, on treatment with apoptotic cells and LPS, the migrating DCs are able to recruit naive T cells to generate TH1 immune responses. Our results show that the cotreatment of DCs with apoptotic tumor cells and inflammatory signals is promising for the design of an antitumoral DC-based vaccine. (Blood. 2005;106:1734-1741)

All- trans retinoic acid biases immune response induced by DNA vaccine in a Th2 direction

Vitamin A deficiency diminishes Th2-mediated Ab responses. Providing Vitamin A or its active metabolites reverses this defect. All- trans retinoic acid (ATRA), an acid derivation of Vitamin A, regulates the balance of immune response induced by TR421-hCGβ DNA vaccine. Compared to DNA vaccine alone or treatment with vehicle, significantly higher level of antibody against the protein encoded by DNA vaccine was observed in mice 6 weeks after the first immunization. The IgG2a/IgG1 ratio was lower in mice treated with ATRA. We also found that treatment with ATRA also diminishes specific cellular immune response induced by gene immunization by measuring the marker of cellular immune response. We conclude that ATRA biases the immune response to Th2 direction induced by DNA vaccine and acts as a candidate adjuvant and immunomodulatory molecule.