CD8(+) T cells regulate immune responses in a murine model of allergen-induced sensitization and airway inflammation

The role of CD8(+) T cells in the development of allergic airway disease is controversial. On the one hand, CD8(+) T cells are known to inhibit the development of airway hyperreactivity (AHR) in murine models of asthma. In humans, IL-10-producing CD8(+) T cells were shown to act as regulatory cells, inhibiting both proliferation and cytokine secretion of T cells. On the other hand, CD8(+) T cells can promote IL-5-mediated eosinophilic airway inflammation and the development of AHR in animal models. To examine this, we investigated the role of CD8(+) T cells during the induction of allergen-induced AHR and demonstrated a protective effect of CD8(+) T cells. Depletion of CD8(+) T cells prior to the immunization led to increased Th2 responses and increased allergic airway disease. However, after development of AHR, CD8(+) T cells that infiltrated the lungs secreted high levels of IL-4, IL-5 and IL-10, but little IFN-gamma, whereas CD8(+) T cells in the peribronchial lymph nodes or spleen produced high levels of IFN-gamma, but little or no Th2 cytokines. These data demonstrate protective effects of CD8(+)T cells against the induction of immune responses and show a functional diversity of CD8(+) T cells in different compartments of sensitized mice.     

Absence of significant Th2 response in diabetes-prone non-obese diabetic (NOD) mice.

Accumulating evidence suggests that Th1 T cells play a pivotal role in the development of autoimmune diabetes. Conversely, promoting a Th2 response inhibits disease progression. However, it has not been determined whether Th2 cells are regulatory T cells that fail at the time of diabetes development in naive non-diabetic NOD mice. Therefore, in order to evaluate cytokine secretion by spleen and islet infiltrating T cells in NOD mice at different stages of the autoimmune process, we developed an ELISPOT assay that detects IL-2, IL-4, and interferon-gamma (IFN-gamma) secretion in vitro at the single-cell level. We showed that, whatever the age considered, IFN-gamma is predominantly secreted, and that no IL-4-secreting cells are detected in the islets of male and female NOD mice. Spleen cells from 8-week-old female NOD mice, which include regulatory suppressor T cells, do not secrete IL-4, either upon presentation of islet cell antigens in vitro, or after transfer in vivo, but do secrete IFN-gamma. IFN-gamma secretion by T cells from diabetic mice results from CD4 but not CD8 T cells in transfer experiments into NOD/severe combined immunodeficient (SCID) recipients. These results suggest that (i) detection of regulatory CD4 T cells in NOD mice is not paralleled by a Th2 response; (ii) beta cell destruction does not depend on a switch from a Th2 to a Th1-type response; and (iii) CD8 T cells do not participate in induction of diabetes by secreting IFN-gamma.     

The IL-1 receptor 1 is critical for Th2 cell type airway immune responses in a mild but not in a more severe asthma model

IL-1 alpha and IL-1 beta are potent pro-inflammatory cytokines that regulate many physiological systems by binding and signaling to the same receptor termed IL-1 receptor type 1 (IL-1R1). We have investigated the role of IL-1 for pulmonary immune responses in models of allergic asthma using IL-1R1-deficient (IL-1R1(-/-)) mice. In a model of mild asthma, based on repeated sensitization of mice with low doses of ovalbumin in the absence of any adjuvant and multiple intranasal challenges, the pulmonary eosinophilic inflammation and goblet cell hyperplasia were strongly reduced in IL-1R1(-/-) as compared to control BALB/c mice. Moreover, priming of CD4(+) T cells in bronchial lymph nodes and their recruitment to the lung was affected in IL-1R1(-/-) mice associated with impaired antibody responses including IgG, IgE, and IgA. In contrast, sensitization of mice in the presence of alum adjuvant, a more severe asthma model, rendered the IL-1 pathway dispensable for the development of pulmonary allergic Th2 responses, as eosinophilic inflammation, antibody responses, and CD4(+) T cell priming in lymph nodes were comparable between IL-1R1(-/-) and wild-type mice. These results suggest a critical role of IL-1/IL-1R1 for development of allergic Th2 responses, but its requirement can be overcome by using alum as adjuvant for sensitization.     

Synthetic glycolipid OCH prevents insulitis and diabetes in NOD mice

Non-obese diabetic (NOD) mice develop diabetes mediated by pathogenic T-helper type 1 (Th1) cells. V alpha 14 Natural killer (NKT) cells are a unique lymphocyte subtype implicated in the regulation of autoimmunity and a good source of protective Th2 cytokines. We recently developed a Th2-skewing NKT cell ligand, OCH. OCH, a sphingosine truncated derivative of alpha-galactosylceramide (alpha-GC), stimulates NKT cells to selectively produce Th2 cytokines. Here we show that OCH prevented the development of diabetes and insulitis in NOD mice. The suppression of insulitis by OCH was more profound compared to alpha-GC. Infiltration of T cells, B cells and macrophages into islets is inhibited in OCH-treated NOD mice. OCH-mediated suppression of diabetes is associated with Th2 bias of anti-islet antigen response and increased IL-10 producing cells among islet-infiltrating leukocytes. Considering the non-polymorphic and well conserved features of the CD1d molecule in mice and humans, these findings not only support the proposed role of NKT cells in the regulation of self-tolerance but also highlight the potential use of OCH for therapeutic intervention in type I diabetes.     

Cytometric and functional analyses of NK and NKT cell deficiencies in NOD mice.

Defects in NK and NKT cell activities have been implicated in the etiology of type 1 (autoimmune) diabetes in NOD mice on the basis of experiments performed using surrogate phenotypes for the identification of these lymphocyte subsets. Here, we have generated a congenic line of NOD mice (NOD.b-Nkrp1(b)) which express the allelic NK1.1 marker, enabling the direct study of NK and NKT cells in NOD mice. Major deficiencies in both populations were identified when NOD.b-Nkrp1(b) mice were compared with C57BL/6 and BALB.B6-Cmv1(r) mice by flow cytometry. The decrease in numbers of peripheral NK cells was associated with an increase in their numbers in the bone marrow, suggesting that a defect in NK cell export may be involved. In contrast, the most severe deficiency of NKT cells found was in the thymus, indicating that defects in thymic production were probably responsible. The deficiencies in NK cell activity in NOD mice could only partly be accounted for by the reduced numbers of NK cells, and fewer NKT cells from NOD mice produced IL-4 following stimulation, suggesting that NK and NKT cells from NOD mice shared functional deficiencies in addition to their numerical deficiencies. Despite the relative lack of IL-4 production by NOD NKT cells, adoptive transfer of alpha beta TCR(+)NK1.1(+) syngeneic NKT cells into 3-week-old NOD recipients successfully prevented the onset of spontaneous diabetes. As both NK and NKT cells play roles in regulating immune responses, we postulate that the synergistic defects reported here contribute to the susceptibility of NOD mice to autoimmune disease.     

Reovirus type-2 infection in newborn DBA/1J mice reduces the development of late allergic asthma

The aim of the present study was to determine whether or not the development of a helper T (Th) 1 response induced by Reovirus type-2 (Reo-2) infection would protect against the development of Th2-mediated late allergic asthma. This hypothesis was examined by infecting one day old neonatal DB A/1J mice with Reo-2 in an ovalbumin (OVA)-induced late asthma model. Compared with the controls (either infected or uninfected mice with or without OVA sensitization and/or OVA challenge), Reo-2 infection lessened the magnitude of the subsequent allergic Th2-mediated late asthma. In infected mice with allergic late asthma, there was decreased infiltration of interleukin (IL)-4(+), IL-5(+), IL-13(+) and very late antigen (VLA)-4(+) lymphocytes, and eotaxin-2(+) and VLA-4(+) eosinophils, in both bronchial and bronchiolar lesions. Also the expression of vascular cell adhesion molecule (VCAM)-1 and eotaxin-2 on vascular endothelial cells was reduced. Moreover, the systemic production of IL-4, IL-5, tumour necrosis factor-α and OVA-specific IgE was reduced, whereas systemic IFN-γ production was increased. In addition, there was no increase in IFN-α production. Thus the present study suggests that systemic Reo-2 infection at birth may reduce the development of subsequent late allergic asthma by the induction of a Th1 response. Therefore the potential suppressive mechanism(s) that might be induced by Reo-2 infection in newborn mice and their effects on the development of late allergic asthma are discussed.     

Critical role for OX40 ligand in the development of pathogenic Th2 cells in a murine model of asthma

Bronchial asthma is characterized by massive infiltration of eosinophils and airway hyperreactivity (AHR), which are caused by overproduction of Th2 cytokines (IL-4, IL-5, and IL-13) by allergen-specific T cells. We recently demonstrated a critical contribution of OX40 ligand (OX40L) to the development of Th2-mediated experimental leishmaniasis. In this study, we have examined the role of OX40L in the development of Th2-mediated pulmonary inflammation by utilizing OX40L-deficient mice and a neutralizing anti-OX40L mAb in a murine model of asthma. Sensitization and airway challenge with ovalbumin in wild-type BALB/c mice induced a typical allergic asthma characterized by AHR, accumulation of eosinophils, increased mucus production, and high levels of Th2 cytokines in the lung.All these asthmatic responses were not induced in OX40L-deficient BALB/c mice. Administration of neutralizing anti-OX40L mAb in wild-type BALB/c mice during the sensitization period also abolished the induction of asthmatic responses. In contrast, administration of anti-OX40L mAb during the challenge period did not inhibit the asthmatic responses. These results indicate a critical role for OX40L in the induction phase, which leads to the development of pathogenic Th2 cells, but not in the effector phase, which includes migration and activation of pathogenic Th2 cells in the lung.     

The natural killer T cell ligand alpha-galactosylceramide prevents or promotes pristane-induced lupus in mice

Systemic lupus erythematosus is a systemic autoimmune disease characterized by inflammation in organs such as kidneys and presence of autoantibodies against nuclear antigens. We have previously shown that CD1d deficiency in BALB/c mice exacerbates lupus nephritis and autoantibody production induced by the hydrocarbon oil pristane. Here, we have tested the impact of activating CD1d-restricted natural killer T (NKT) cells on pristane-induced lupus-like autoimmunity in BALB/c and SJL mice. Repeated in vivo treatment of pristane-injected BALB/c mice with the NKT cell ligand alpha-galactosylceramide (alpha-GalCer) prior to the onset of florid disease suppressed proteinuria, in a manner that was dependent on CD1d and IL-4 expression. In sharp contrast, however, similar treatment of pristane-injected SJL mice with alpha-GalCer resulted in increased proteinuria. Consistent with these dichotomous effects of NKT cell activation on the development of lupus-like autoimmunity, NKT cells in BALB/c and SJL/J mice exhibited a mixed Th1/Th2 and a Th1-biased cytokine production profile, respectively. These findings demonstrate that NKT cell activation with alpha-GalCer suppresses or promotes pristane-induced lupus-like autoimmunity in mice, in a strain-dependent manner.     

Invariant NKT cells regulate experimental autoimmune uveitis through inhibition of Th17 differentiation

Although NKT cells have been implicated in diverse immunomodulatory responses, the effector mechanisms underlying the NKT cell-mediated regulation of pathogenic T helper cells are not well understood. Here, we show that invariant NKT cells inhibited the differentiation of CD4(+) T cells into Th17 cells both in vitro and in vivo. The number of IL-17-producing CD4(+) T cells was reduced following co-culture with purified NK1.1(+) TCR(+) cells from WT, but not from CD1d(-/-) or Jα18(-/-) , mice. Co-cultured NKT cells from either cytokine-deficient (IL-4(-/-) , IL-10(-/-) , or IFN-γ(-/-) ) or WT mice efficiently inhibited Th17 differentiation. The contact-dependent mechanisms of NKT cell-mediated regulation of Th17 differentiation were confirmed using transwell co-culture experiments. On the contrary, the suppression of Th1 differentiation was dependent on IL-4 derived from the NKT cells. The in vivo regulatory capacity of NKT cells on Th17 cells was confirmed using an experimental autoimmune uveitis model induced with human IRBP(1-20) (IRBP, interphotoreceptor retinoid-binding protein) peptide. NKT cell-deficient mice (CD1d(-/-) or Jα18(-/-) ) demonstrated an increased disease severity, which was reversed by the transfer of WT or cytokine-deficient (IL-4(-/-) , IL-10(-/-) , or IFN-γ(-/-) ) NKT cells. Our results indicate that invariant NKT cells inhibited autoimmune uveitis predominantly through the cytokine-independent inhibition of Th17 differentiation.     

NOD/SCID小鼠胎盘细胞内细胞因子表达及其与妊娠转归的关系

目的：研究Th1和Th2型细胞因子在胎盘淋巴细胞内的表达状况及其与NOD/SCID孕鼠妊娠转归的关系。 方法： 比较BALB/c和NOD/SCID小鼠孕13.5 d胚胎吸收率(RR), 采用4色流式细胞术检测胎盘淋巴细胞内Th1型(TNF-α和IL-2)和Th2型(IL-10)细胞因子表达率。 结果： 虽然NOD/SCID小鼠存在多重免疫缺陷，但BALB/c和NOD/SCID小鼠孕13.5 d RR无显著差异；NOD/SCID×NOD/SCID母-胎界面CD8+IL-10+/CD8+细胞百分率显著高于BALB/c×BALB/c妊娠模型(P<0.01), 而CD4和CD8阳性细胞内TNF-α和IL-2表达水平均无显著差异。 结论： 母-胎界面CD8+IL-10+/CD8+细胞百分率自发性升高可能与NOD/SCID小鼠基本正常的生育力有关。     

IFN-γ induced by IL-12 administration prevents diabetes by inhibiting pathogenic IL-17 production in NOD mice

Interleukin 12 (IL-12) is a pivotal Th1-associated cytokine and a potent immunoregulatory molecule. However, the role of IL-12 in inducing immune tolerance that prevents insulitis and inhibits type 1 diabetes (T1D) remains unknown. The aim of this study was to investigate whether intermittent administration of IL-12 could prevent the development of T1D in nonobese diabetic (NOD) mice. We examined whether IL-12 treatment prevented diabetes by injecting different doses of IL-12 into NOD mice and compared the incidence of diabetes and insulitis in NOD mice with the incidence in control mice. Furthermore, we investigated the potential mechanisms of IL-12-mediated prevention of diabetes and insulitis. The expression of pro-inflammatory and immunoregulatory cytokines was measured before and following therapeutic administration of IL-12 in NOD mice. Our data demonstrated that both the absolute number and the function of DCs were impaired in NOD mice and that the levels of the Th17-associated pro-inflammatory cytokines, IL-1β, IL-6 and IL-23, were elevated in NOD mice compared with age-matched BALB/c and C57BL/6 mice. However, treatment of NOD mice with IL-12 suppressed insulitis and increased the number of healthy islets, and the levels of IL-17, IL-1β, IL-6 and IL-23 were significantly decreased. Moreover, IL-12 treatment of NOD mice induced the secretion of IFN-γ, a potent inhibitor of Th17 cells. These data indicated that intermittent administration of IL-12 prevented diabetes by inducing IFN-γ, suppressing the pathogenic IL-17-producing cells and reducing the expression of Th17-associated pro-inflammatory cytokines. Our results suggest a promising strategy for the treatment of human T1D and other Th17 cell-mediated autoimmune diseases.     

Influence of respiratory syncytial virus infection on cytokine and inflammatory responses in allergic mice

BACKGROUND: Th2 lymphocyte responses are associated with inflammation and disease during allergic responses. Exposure to particular environmental factors during the expression of allergy could result in more pronounced Th2-like immune responses and more severe disease. One factor might be a respiratory virus infection. OBJECTIVE: The aim of our study was to investigate the influence of respiratory syncytial virus (RSV) infection on the expression of ovalbumin (OVA)-induced allergy in BALB/c mice. METHODS: We determined OVA-specific IgE in serum, cytokine profiles and histopathological lesions in lungs of OVA-allergic mice after RSV infection. RESULTS: OVA sensitization and challenge induced OVA-specific IgE in serum, Th2 cytokine mRNA expression, and mononuclear and eosinophilic inflammation in the lungs. RSV inoculation during the challenge period enhanced OVA-induced IL-4 and IL-5 mRNA expression in lung tissue. RSV further enhanced the OVA-induced hypertrophy of mucous cells and eosinophilic infiltration in lung tissue. Surprisingly, RSV infection decreased Th2 cytokine secretion and eosinophilic influx in bronchoalveolar lavage of OVA-allergic mice. Because inactivated RSV did not influence these responses, replication of RSV appeared essential for the modification of OVA-induced Th2 cytokine expression. RSV did not change OVA-specific IgE levels in serum. Furthermore, the RSV-induced IL-12 mRNA expression in lung tissue of OVA-allergic mice was diminished, but IFN-gamma mRNA expression was not affected. CONCLUSION: RSV infection enhanced particular OVA-induced Th2 cytokine mRNA responses and pulmonary lesions in allergic mice and thus aggravated allergic respiratory disease.     

Effects of allergic airway disease on mouse adenovirus type 1 respiratory infection

Virus infection may contribute to asthma pathogenesis. In turn, a Th2-polarized pulmonary environment may increase host susceptibility to infection. We used a cockroach antigen (CRA) model of allergic airway disease to test the hypothesis that Th2 cytokine overproduction increases susceptibility to mouse adenovirus type 1 (MAV-1). CRA sensitization led to upregulated lung expression of IL-4 and IL-13, lung cellular inflammation, and exaggerated airway mucus production. Following intranasal MAV-1 infection, lung cellular inflammation was more pronounced in CRA-sensitized mice than in unsensitized mice at 7 days post-infection but not at a later time point. CRA sensitization did not significantly suppress lung IFN-γ expression, and lung IFN-γ expression was upregulated in both CRA-sensitized mice and unsensitized mice over the course of MAV-1 infection. Despite CRA-induced differences in pulmonary inflammation, MAV-1 viral loads in lung and spleen and MAV-1 gene expression in the lung did not differ between CRA-sensitized and unsensitized mice. Our data therefore suggest that MAV-1 pathogenesis is not affected directly or indirectly by the Th2 polarization associated with allergic airway disease.     

Mechanisms of Mycobacterium avium-induced resistance against insulin-dependent diabetes mellitus (IDDM) in non-obese diabetic (NOD) mice: role of Fas and Th1 cells

NOD mice spontaneously develop autoimmune diabetes. One of the manipulations that prevent diabetes in NOD mice is infection with mycobacteria or immunization of mice with mycobacteria-containing adjuvant. Infection of NOD mice with Mycobacterium avium, done before the mice show overt diabetes, results in permanent protection of the animals from diabetes and this protective effect is associated with increased numbers of CD4⁺ T cells and B220⁺ B cells. Here, we investigate whether the M. avium-induced protection of NOD mice from diabetes was associated with changes in the expression of Fas (CD95) and FasL by immune cells, as well as alterations in cytotoxic activity, interferon-gamma (IFN-γ) and IL-4 production and activation of T cells of infected animals. Our data indicate that protection of NOD mice from diabetes is a Th1-type response that is mediated by up-regulation of the Fas–FasL pathway and involves an increase in the cytotoxicity of T cells. These changes are consistent with induction by the infection of regulatory T cells with the ability of triggering deletion or anergy of peripheral self-reactive lymphocytes that cause the autoimmune disease of NOD mice.     

Induction of active tolerance and involvement of CD1d-restricted natural killer T cells in anti-CD3 F(ab')2 treatment-reversed new-onset diabetes in nonobese diabetic mice

The application of anti-CD3 F(ab')(2) monoclonal antibodies has recently been expanded to treat established autoimmune diseases, including type 1 diabetes. However, the mechanism underlying their effect remains largely unclear. We report that short-phase administration of anti-CD3 F(ab')(2) antibodies efficiently allowed 80% of new-onset, nonobese diabetic (NOD) mice to significantly regain both normoglycemia and pancreatic beta cell-specific autoantigen (ie, glutamic acid decarboxylase and insulin) tolerance, with both effects lasting more than 40 weeks. The responsible mechanism appears to involve the induction and maintenance of a population of immunoregulatory CD1d-restricted natural killer T (NKT) cells, which were marked by an enhanced Th2 response and secretion of elevated levels of interleukin-10. In vivo neutralization of interleukin-4 and/or interleukin-10 bioactivity abrogated this anti-CD3-mediated effect. Importantly, when the cotransfer of NKT cells from the livers of anti-CD3-treated mice and splenocytes from untreated, acutely diabetic NOD mice was performed in NOD-severe combined immunodeficient mice, the NKT cells were sufficient to either delay or prevent the onset of diabetes compared with controls where only splenocytes were introduced. These data suggest that CD1d-restricted NKT cells may play a critical role in anti-CD3 antibody-induced diabetes remission and the restoration of immune tolerance.     

Limited effect of CpG ODN in preventing type 1 diabetes in NOD mice

Type 1 diabetes is considered as Th1 cell mediated autoimmune disease and the suppression of Th1 cells or the activation of Th2 cells has been regarded as a plausible immunologic intervention for the prevention of type 1 diabetogenesis in a rodent model. CpG ODN is an immunostimulatory sequence primarily present in bacterial DNA, viral DNA and BCG. CpG ODN is conventionally classified as a Th1 cell activator, which has been clinically applied to cancer, allergy and infectious disease. Recently, there was a promising report of that CpG ODN administration suppressed the development of type 1 diabetes in NOD mice by inducing Th2 cell mediated cytokine. However, the antidiabetogenic effect of CpG ODN on NOD mice is controversial. Thus, two studies were serially undertaken with various kinds of CpG motif to find a more optimal sequence and administration method. In the first study, CpG ODN was vaccinated four times and pancreatic inflammation and the quantity of serum insulin subsequently evaluated. In the second study, the amounts of IFN gamma and IL-4 in sera were measured as representative cytokines of Th1 and Th2 cells, respectively. As a result, vaccination or continuous injection of CpG ODN failed to show a preventive effect on type 1 diabetogenesis in NOD mice. Structural differences of CpG ODN also had no affect on the result. CpG ODN also consistently showed affect on the pancreatic pathology. The productions of IFN gamma and IL-4 were detected only in the K and D type CpG ODN administration groups. Comparison of the two cytokines leads to the conclusion that CpG ODN generated a Th1-weighted response in both study groups. It was assumed that CpG ODN failed to produce Th2-weighted cytokine milieu, which can overcome the genetically determined phenotype of NOD mice. Given these results, it was concluded that the immunotherapeutic application of CpG ODN on Type 1 diabetes had clear limitations.     

Pulmonary innate lymphoid cells are major producers of IL-5 and IL-13 in murine models of allergic asthma

Allergic asthma is characterized by chronic airway inflammation and hyperreactivity and is thought to be mediated by an adaptive T helper-2 (Th2) cell-type immune response. Here, we demonstrate that type 2 pulmonary innate lymphoid cells (ILC2s) significantly contribute to production of the key cytokines IL-5 and IL-13 in experimental asthma. In naive mice, lineage-marker negative ILC2s expressing IL-7Rα, CD25, Sca-1, and T1/ST2(IL-33R) were present in lungs and mediastinal lymph nodes (MedLNs), but not in broncho-alveolar lavage (BAL) fluid. Upon intranasal administration of IL-25 or IL-33, an asthma phenotype was induced, whereby ILC2s accumulated in lungs, MedLNs, and BAL fluid. After IL-25 and IL-33 administration, ILC2s constituted ～50 and ～80% of IL-5(+) /IL-13(+) cells in lung and BAL, respectively. Also in house dust mite-induced or ovalbumin-induced allergic asthma, the ILC2 population in lung and BAL fluid increased significantly in size and ILC2s were a major source of IL-5 or IL-13. Particularly in OVA-induced asthma, the contribution of ILC2s to the total population of intracellular IL-5(+) and IL-13(+) cells in the lung was in the same range as found for Th2 cells. We conclude that both ILC2s and Th2 cells produce large amounts of IL-5 and IL-13 that contribute to allergic airway inflammation.     

Bone marrow-derived mesenchymal stromal cells inhibit Th2-mediated allergic airways inflammation in mice

Bone marrow-derived mesenchymal stromal cells (BMSCs) mitigate inflammation in mouse models of acute lung injury. However, specific mechanisms of BMSC actions on CD4 T lymphocyte-mediated inflammation in vivo remain poorly understood. Limited data suggests promotion of Th2 phenotype in models of Th1-mediated diseases. However, whether this might alleviate or worsen Th2-mediated diseases such as allergic asthma is unknown. To ascertain the effects of systemic administration of BMSCs in a mouse model of Th2-mediated allergic airways inflammation, ovalbumin (OVA)-induced allergic airways inflammation was induced in wild-type C57BL/6 and BALB/c mice as well as in interferon-γ (IFNγ) receptor null mice. Effects of systemic administration during antigen sensitization of either syngeneic or allogeneic BMSC on airways hyperreactivity, lung inflammation, antigen-specific CD4 T lymphocytes, and serum immunoglobulins were assessed. Both syngeneic and allogeneic BMSCs inhibited airways hyperreactivity and lung inflammation through a mechanism partly dependent on IFNγ. However, contrary to existing data, BMSCs did not affect antigen-specific CD4 T lymphocyte proliferation but rather promoted Th1 phenotype in vivo as assessed by both OVA-specific CD4 T lymphocyte cytokine production and OVA-specific circulating immunoglobulins. BMSCs treated to prevent release of soluble mediators and a control cell population of primary dermal skin fibroblasts only partly mimicked the BMSC effects and in some cases worsened inflammation. In conclusion, BMSCs inhibit Th2-mediated allergic airways inflammation by influencing antigen-specific CD4 T lymphocyte differentiation. Promotion of a Th1 phenotype in antigen-specific CD4 T lymphocytes by BMSCs is sufficient to inhibit Th2-mediated allergic airways inflammation through an IFNγ-dependent process.     

Airway cytokine responses to acute and repeated stress in a murine model of allergic asthma

Although stress is known to exacerbate asthma, the underlying mechanisms are unclear. Using a murine model of allergic asthma, Th1 (interleukin [IL]-2 and gamma-interferon [IFN-γ]) and Th2 (IL-4 and IL-5) airway cytokine responses and Th1:Th2 cytokine ratios to acute and repeated stress were examined in bronchoalveolar lavage fluid (BALF). Asthmatic mice showed significantly higher IL-4 level and Th2 predominance, compared with healthy mice. To acute stress, asthmatic mice significantly increased IL-4 but decreased IFN-γ levels favoring Th2 predominance, whereas healthy mice significantly decreased IL-4 level favoring Th1 predominance in BALF. To repeated stress, asthmatic mice significantly decreased IFN-γ, IL-4 and IL-5 levels overall favoring Th1 predominance, whereas healthy mice basically maintained the same response profile shown to acute stress. These findings suggest that a significant shift toward Th2 predominance in asthmatic mice under acute stress may be a mechanism underlying exacerbation of asthma.     

Receptor Interacting Protein 2 (RIP2) Is Dispensable for OVA-Induced Airway Inflammation in Mice

Purpose

Asthma is a pulmonary chronic inflammatory disease characterized by airway obstruction and hyperresponsiveness. Pattern recognition receptors are known to play a key role in the development of allergic diseases as well as host defenses against microbial infection. Receptor interacting protein 2 (RIP2), a serine/threonine kinase, is an adaptor molecule of NOD1 and NOD2, and genetic variation in this receptor is known to be associated with the severity of allergic asthma in children. In this study, we examined the role of RIP2 in the development of allergic airway inflammation in a mouse model.

Methods

Airway inflammation was induced in mice through intranasal administration of ovalbumin (OVA) after 2 intraperitoneal immunizations with OVA. Lung inflammation and mucus hypersecretion were examined histologically and total cell infiltration in bronchoalveolar (BAL) fluids was determined. Levels of the Th2-related cytokines, IL-5 and IL-13, in lung extracts were measured by ELISA. Serum antigen-specific IgE and IgG1 levels were also assessed.

Results

OVA-induced lung inflammation and mucus hypersecretion were not different between WT and RIP2-deficient mice. The IL-5 and IL-13 levels in the bronchoalveolar (BAL) fluids were also not impaired in RIP2-deficient mice compared to WT mice. Moreover, RIP2 deficiency did not affect serum OVA-specific IgG1 and IgE levels.

Conclusions

Our results suggest that RIP2 is not associated with the development of allergic airway inflammation.