Expression of the Th1 chemokine IFN-gamma-inducible protein 10 in the airway alters mucosal allergic sensitization in mice

A novel herbal composition containing extracts of Boswellia serrata gum resin and Aegle marmelos fruit alleviates symptoms of asthma in a placebo controlled double-blind clinical study

LI13109F is a novel herbal composition containing the extracts of Boswellia serrata gum resin and Aegle marmelos fruit. This composition dampens leukotriene dependent inflammatory reactions via inhibiting 5-lipoxygenase pathway. In a Sephadex LH-20 induced airway inflammation model of Sprague Dawley rats, LI13109F significantly reduced infiltrated granulocyte population in the bronco-alveolar lavage fluid and normalized Th1/Th2 cytokine balance. Further, a 56-day placebo-controlled and randomized double blind study (Clinical Trial Registration No. CTRI/2016/10/007393) on subjects with mild to moderate asthma has evaluated the clinical efficacy of LI13109F. The study subjects received either 200 mg/day of LI13109F (n = 18) or a similar dosage of placebo (n = 18). At the end of the trial period, LI13109F conferred significant improvements in the clinical parameters; the emotional function (p = .0305) and asthma symptoms scores (p = .0002) were improved even at 14 days, compared with the placebo. Further, 56 days supplementation of LI13109F resulted in significant increase in serum IFN-γ (p = .0014) and reduction in IL-4 (p = .0497), compared with placebo. LI13109F supplementation did not yield any serious adverse events or any abnormal observations in routine laboratory examinations during the study. Together, these observations suggest that LI13109F (AlvioLife®) is tolerable and an effective intervention for management of mild to moderate asthma such as airway inflammation.

Selected CC and CXC chemokines in children with atopic asthma

INTRODUCTION

There are only limited data on CC and CXC chemokines regulation in children with asthma.

AIM

We compared the serum profile of selected CC and CXC chemokines in patients with atopic asthma and healthy children.

MATERIAL AND METHODS

Serum concentration of CC chemokines RANTES, MCP-1, and CXC chemokines IP-10, MIG, IL-8, RANTES was measured using cytometric bead array in 44 children with atopic asthma and 17 healthy subjects.

RESULTS

The concentration of RANTES was significantly higher and the MIG level was lower in all children with asthma as compared to their control counterparts. We observed increased RANTES and decreased MIG levels also in patients with stable asthma when compared with children in the control group. The IP-10 concentration was similar between the whole asthma group and healthy controls, while significantly increased levels of this chemokine in acute asthma have been observed when compared to stable asthma. For MCP-1 and IL-8, the serum concentration was similar in all compared groups. The MIG concentration correlated positively with IP-10, IL-8, and CRP levels and negatively with the eosinophil count. A negative correlation between the IP-10 and eosinophil count and a negative correlation between FEV1 and IP-10 were found.

CONCLUSIONS

An increased serum RANTES level in children with asthma may result in enhancement of Th2 lymphocyte recruitment into the airway. A decreased expression of Th1 chemokine MIG in children with stable asthma may contribute to a diminished antagonizing effect on Th2 cytokine production and hence intensify Th2 predominance. An increased IP-10 level in children during an asthma attack suggest that this chemokine is a serological marker of disease exacerbation.

Chemokine-based immunotherapy: delivery systems and combination therapies

A major role of chemokines is to mediate leukocyte migration through interaction with G-protein-coupled receptors. Various delivery systems have been developed to utilize the chemokine properties for combating disease. Viral and mutant viral vectors expressing chemokines, genetically modified dendritic cells with chemokine or chemokine receptors, engineered chemokine-expressing tumor cells and pDNA encoding chemokines are among these methods. Another approach for inducing a targeted immune response is fusion of a targeting antibody or antibody fragment to a chemokine. In addition, chemokines induce more effective antitumor immunity when used as adjuvants. In this regard, chemokines are codelivered along with antigens or fused as a targeting unit with antigenic moieties. In this review, several chemokines with their role in inducing immune response against different diseases are discussed, with a major emphasis on cancer.

Experimental advances in understanding allergic airway inflammation

Asthma is largely an inflammatory disease, with the development of T cell mediated inflammation in the lung following exposure to allergen or other precipitating factors. Currently, the major therapies for this disease are directed either at relief of bronchoconstriction (ie beta-agonists) or are non-specific immunomodulators (ie, corticosteroids). While much attention has been paid to factors that regulate the initiation of an inflammatory response, chronic inflammation may also be due to defects in regulatory mechanisms that limit or terminate immune responses. In this review, we explore the elements controlling both the recruitment of T cells to the lung and their function. Possibilities for future therapeutic intervention are highlighted.

CXCL10 reduces melanoma proliferation and invasiveness in vitro and in vivo

BACKGROUND

Melanoma is often infiltrated by inflammatory and immune cells that might either maintain chronic inflammation, therefore promoting tumour growth, or mount an antitumour response to control tumour outcome. In this setting, Th1-oriented lymphocyte infiltration is associated with a better outcome in melanoma. Although the interferon-induced protein CXCL10 is expressed by Th1 immune cells, its receptor was also shown to be involved in melanoma progression and metastasis.

OBJECTIVES

To investigate the CXCL10-mediated antitumoral response in vivo, and its clinical relevance. Methods  C57BL/6 mice bearing B16F1 melanoma were treated intraperitoneally with an adenovirus vector expressing CXCL10. In addition, peripheral blood mononuclear cells (PBMC) from 20 patients, 10 with melanoma in remission and 10 with melanoma in progression, were assessed for their cytokine/chemokine content using a 30-plex assay, and for their ability to modulate melanoma invasion in vitro in Transwell(®) (Sigma-Aldrich) chambers coated with Matrigel(®) (BD Biosciences).

RESULTS

Treatment with CXCL10 reduced melanoma tumour growth in C57BL/6 mice compared with controls in vivo, and reduced melanoma invasion in vitro. Screening for expression of 30 cytokine/chemokine proteins showed that only CXCL10 was significantly increased in patients in remission compared with patients in progression. PBMC only from patients in remission significantly reduced melanoma cell invasiveness in an ex vivo Transwell(®) assay. Accordingly, this inhibitory effect was also observed with PBMC culture media from patients with melanoma in remission.

CONCLUSIONS

The quantitative increase in CXCL10 production, together with its ability to limit melanoma progression, shows the potential benefit of this chemokine to control melanoma progression or metastasis.

Current understanding of Pneumocystis immunology

Pneumocystis jirovecii is the opportunistic fungal organism that causes Pneumocystis pneumonia (PCP) in humans. Similar to other opportunistic pathogens, Pneumocystis causes disease in individuals who are immunocompromised, particularly those infected with HIV. PCP remains the most common opportunistic infection in patients with AIDS. Incidence has decreased greatly with the advent of HAART. However, an increase in the non-HIV immunocompromised population, noncompliance with current treatments, emergence of drug-resistant strains and rise in HIV(+) cases in developing countries makes Pneumocystis a pathogen of continued interest and a public health threat. A great deal of research interest has addressed therapeutic interventions to boost waning immunity in the host to prevent or treat PCP. This article focuses on research conducted during the previous 5 years regarding the host immune response to Pneumocystis, including innate, cell-mediated and humoral immunity, and associated immunotherapies tested against PCP.

Chronic inflammation and asthma

Allergic asthma is a complex and chronic inflammatory disorder which is associated with airway hyper-responsiveness and tissue remodelling of the airway structure. Although originally thought to be a Th2-driven inflammatory response to inhaled innocuous allergen, the immune response in asthma is now considered highly heterogeneous. There are now various in vivo systems which have been designed to examine the pathways leading to the development of this chronic immune response and reflect, in part this heterogeneity. Furthermore, the emergence of endogenous immunoregulatory pathways and active pro-resolving mediators hold great potential for future therapeutic intervention. In this review, the key cellular and molecular mediators relating to chronic allergic airway disease are discussed, as well as emerging players in the regulation of chronic allergic inflammation.

Protective immunity to Mycobacterium tuberculosis infection by chemokine and cytokine conditioned CFP-10 differentiated dendritic cells

Background

Dendritic cells (DCs) play major roles in mediating immune responses to mycobacteria. A crucial aspect of this is the priming of T cells via chemokines and cytokines. In this study we investigated the roles of chemokines RANTES and IP-10 in regulating protective responses from Mycobacterium tuberculosis (M. tb) 10 kDa Culture Filtrate Protein-10 (CFP-10) differentiated DCs (CFP10-DCs).

Methods and Findings

Infection of CFP10-DCs with mycobacteria down-modulated RANTES and IP-10 levels. Pathway specific microarray analyses showed that in addition to RANTES and IP-10, mycobacteria infected CFP10-DCs showed reduced expression of many Th1 promoting chemokines and chemokine receptors. Importantly, T cells co-cultured with RANTES and IP-10 conditioned CFP10-DCs mediated killing of mycobacteria from infected macrophages. Similarly, T cells recruited by RANTES and IP-10 conditioned CFP10-DCs mediated significant killing of mycobacteria from infected macrophages. IFN-gamma treatment of CFP10-DCs restored RANTES and IP-10 levels and T cells activated by these DCs mediated significant killing of virulent M. tb inside macrophages. Adoptive transfer of either RANTES and IP-10 or IL-12 and IFN-gamma conditioned CFP10-DCs cleared an established M. tb infection in mice. The extent of clearance was similar to that obtained with drug treatment.

Conclusions

These results indicate that chemokine and cytokine secretion by DCs differentiated by M. tb antigens such as CFP-10 play major roles in regulating protective immune responses at sites of infection.

Generation of Th1 and Th2 chemokines by human eosinophils: evidence for a critical role of TNF-alpha

Emerging evidence suggests a role for eosinophils in immune regulation of T cells. Thus, we sought to determine whether human eosinophils may exert their effect via differential generation of Th1 and Th2 chemokines depending on cytokines in their microenvironment and, if so, to establish the conditions under which these chemokines are produced. Eosinophils cultured with TNF-alpha plus IL-4 had increased mRNA expression and protein secretion of the Th2-type chemokines, CCL17 (thymus and activation-regulated chemokine) and CCL22 (macrophage-derived chemokine). Conversely, the Th1-type chemokines, CXCL9 (monokine induced by IFN-gamma) and CXCL10 (IFN-gamma-inducible protein-10), were expressed after stimulation with TNF-alpha plus IFN-gamma. Addition of TNF-alpha appeared to be essential for IFN-gamma-induced release of Th1-type chemokines and significantly enhanced IL-4-induced Th2-type chemokines. Inhibition of NF-kappaB completely blocked the production of both Th1 and Th2 chemokines. Activation of NF-kappaB, STAT6, and STAT1 was induced in eosinophils by TNF-alpha, IL-4, and IFN-gamma, respectively. However, there was no evidence for enhancement of these signaling events when eosinophils were stimulated with the combination of TNF-alpha plus IL-4 or TNF-alpha plus IFN-gamma. Thus, independently activated signaling cascades appear to lead to activation of NF-kappaB, STAT1, and STAT6, which may then cooperate at the promoter level to increase gene transcription. Our data demonstrate that TNF-alpha is a vital component for eosinophil chemokine generation and that, depending on the cytokines present in their microenvironment, eosinophils can promote either a Th2 or a Th1 immune response, supporting an immunoregulatory role for eosinophils.

T-cell activation in occupational asthma and rhinitis

BACKGROUND

Allergic asthma and rhinitis are described as associated with a Th2 activation. However, recent works indicate that a Th1 activation can also be associated with these diseases, concomitantly to a defect in regulatory T (Treg) cell activation. Occupational asthma (OA) and occupational rhinitis (OR) are peculiar cases of these diseases in which the T-cell activation profile is largely unknown.

OBJECTIVE

To characterize T-cell activation induced after a specific inhalation test (SIT) in OA and OR.

MATERIAL AND METHODS

A total of 21 subjects with OA, 10 subjects with OR, 10 exposed nonallergic (ENA) subjects, and 14 healthy volunteers were included. The SIT with the incriminated substance was performed in patients and ENA subjects. Blood and induced sputum were obtained before and after SIT. T cells were analysed for CD69, CD25, IL-13, and IFN-gamma expression by flow cytometry. IL-4 and IFN-gamma were assayed by enzyme-linked immunosorbent assay (ELISA) in cell culture supernatants. Treg cells were identified as CD4(+)CD25(+high)CD45RO(+)CD69(-) T cells in peripheral blood.

RESULTS

Baseline IFN-gamma production was decreased in OA and OR compared with controls. The SIT induced an increase in both Th1 and Th2 cells in blood and sputum from OA. In this group, the proportion of peripheral Treg cells decreased after SIT. Similar results were found in the CD8(+) population. ELISA assays were concordant with flow cytometry. In OR, an attenuated activation profile was found, with an increase in the proportion of IL-13-producing T cells after SIT. By contrast, in ENA subjects, SIT induced Th2 activation, with an increase in Treg cells and a decrease in Th1 cells.

CONCLUSIONS

Our results demonstrate a gradient of T-cell activation from a tolerating profile in ENA subjects to an inflammatory profile in OA, with an intermediate stage in OR.

CXCR3 and IFN protein-10 in Pneumocystis pneumonia

We have previously shown that Tc1 CD8(+) T cells have in vitro and in vivo effector activity against Pneumocystis (PC) infection in mice. Because these cells have preferential expression of CXCR3, we investigated whether CXCR3 was required for host defense activity against PC. Mice deficient in CXCR3 but CD4(+) T cell intact, showed an initial delay but were able to clear the infectious challenge, indicating that CXCR3 signaling is not essential for clearance of PC. CD4-depleted mice had lower levels of monokine induced by IFN-gamma, IFN protein-10 (IP-10), and IFN-inducible T cell alpha-chemoattractant at day 7 of infection and are permissive to PC infection. Overexpression of IP-10 in the lungs by adenoviral gene transfer did not accelerate clearance of infection in control mice but accelerated clearance by day 28 in mice depleted of CD4(+) T cells. This effect was associated with increased recruitment of CD8(+) T to the lungs with higher CXCR3(+) expression levels and enhanced IFN-gamma secretion upon in vitro activation compared with control mice. These results indicate that the CXCR3 chemokines are part of the host defense response to PC, and that IP-10 can direct Tc1 CD8(+) T cell recruitment to the lungs and contribute to host defense against PC even in the absence of CD4(+) T cells.

Interferon-inducible protein 10, but not monokine induced by gamma interferon, promotes protective type 1 immunity in murine Klebsiella pneumoniae pneumonia

CXC chemokines that lack the ELR motif, including interferon-inducible protein 10 [IP-10 (CXCL10)] and monokine induced by gamma interferon (IFN-gamma) [MIG (CXCL9)], have been shown to mediate the generation of type 1 immune responses. In this study, we found that intrapulmonary administration of the gram-negative bacterium Klebsiella pneumoniae resulted in the local and systemic expression of IP-10, followed sequentially by MIG expression. MIG mRNA expression in the lungs of Klebsiella-infected mice required the endogenous production of IFN-gamma, whereas IP-10 was expressed in both an IFN-gamma-dependent and an IFN-gamma-independent fashion. Antibody-mediated neutralization of IP-10 resulted in reduced bacterial clearance and decreased survival, whereas bacterial clearance was unaltered in mice treated with anti-MIG antibody. Impaired bacterial clearance in anti-IP-10 antibody-treated mice was associated with significant reductions in the number and/or activational status of NK and NK-T cells, CD4+ T cells, and gammadelta T cells, as well as a reduction in the expression of IFN-gamma. Conversely, the transient transgenic expression of murine IP-10 using adenovirus-mediated gene transfer resulted in improved bacterial clearance when IP-10 adenovirus was given concomitant with intrapulmonary bacterial challenge. These results indicate that IP-10 is an important component of innate immunity against extracellular bacterial pathogens of the lung and may represent a candidate molecule for immunotherapy in the setting of severe respiratory tract infection.

Role of IFN-gamma in regulating T2 immunity and the development of alternatively activated macrophages during allergic bronchopulmonary mycosis

Pulmonary Cryptococcus neoformans infection of C57BL/6 mice is an established model of a chronic pulmonary fungal infection accompanied by an "allergic" response (T2) to the infection, i.e., a model of an allergic bronchopulmonary mycosis. Our objective was to determine whether IFN-gamma plays a role in regulating the pulmonary T2 immune response in C. neoformans-infected C57BL/6 mice. Long-term pulmonary fungistasis was lost in IFN-gamma knockout (KO) mice, resulting in an increased pulmonary burden of fungi at wk 3. IFN-gamma was required for the early influx of leukocytes into the lungs but was not required later in the infection. By wk 3, eosinophil and macrophage numbers were elevated in the absence of IFN-gamma. The inducible NO synthase to arginase ratio was lower in the lungs of IFN-gamma KO mice and the macrophages had increased numbers of intracellular cryptococci and YM1 crystals, indicative of alternatively activated macrophages in these mice. There was evidence of pulmonary fibrosis in both wild-type and IFN-gamma KO mice by 5 wk postinfection. IFN-gamma production was not required for the development of T2 cytokine (IL-4, IL-5, IL-13) producing cells in the lungs and lung-associated lymph nodes or induction of an IgE response. At a number of time points, T2 cytokine production was enhanced in IFN-gamma KO mice. Thus, in the absence of IFN-gamma, C57BL/6 mice develop an augmented allergic response to C. neoformans, including enhanced generation of alternatively activated macrophages, which is accompanied by a switch from a chronic to a progressive pulmonary cryptococcal infection.

IP-10 mediates selective mononuclear cell accumulation and activation in response to intrapulmonary transgenic expression and during adenovirus-induced pulmonary inflammation

CXC chemokines that lack the glutamine-leucine-arginine (ELR) motif, including interferon (IFN)-inducible protein 10 (IP-10 or CXCL10), have been shown to mediate the generation of type 1 immune responses. In this study, we found that the intrapulmonary transient transgenic expression of murine IP-10 in mice using adenoviral gene transfer resulted in the early accumulation of neutrophils, natural killer (NK) cells, and NK T cells within the lung, followed by the delayed accumulation of CD4+ T cells. Adenovirus-mediated transgenic expression of IP-10 also resulted in selective activation of mononuclear cells, including gamma(delta)-T cells and NK cells, as manifest by CD69 expression or induction of cell-associated IFN-gamma. Importantly, the intratracheal (i.t.) administration of a control human type 5 adenovirus also caused significant accumulation of NK, NK T, and CD4+ T cells, which was maximal at 7 days post vector administration and was associated with the induction of IP-10. Neutralization of endogenous IP-10 in animals receiving control adenovirus resulted in decreases in the numbers of NK, CD4+, and CD8+ T cells. These results indicate that IP-10 can direct the accumulation and activation of neutrophils and selected mononuclear cells to the lung and that adenovirus-induced IP-10 contributes to lung inflammatory cell recruitment/activation observed in response to adenoviral vectors used for gene therapy.

Efficacy of macrophage-activating lipopeptide-2 combined with interferon-gamma in a murine asthma model

RATIONALE

The incidence and prevalence of allergic asthma, caused by Th2-mediated inflammation in response to environmental antigens, is increasing. Epidemiologic data suggest that a lack of Th1-inducing factors may play a pivotal role in the development of this disease. We have previously shown that dendritic cells treated with macrophage-activating lipopeptide-2 (MALP-2) combined with IFN-gamma modulate the Th2 response toward Th1 in an in vitro allergy model.

OBJECTIVE

To test in vivo efficacy of this regime, the effects of the substances were evaluated in a mouse model of allergic airway inflammation.

METHODS

Female Balb/c mice were sensitized to ovalbumin, whereas control animals were sham-sensitized with adjuvant only. After 4 weeks, MALP-2 and IFN-gamma or NaCl, respectively, were intratracheally instillated. After inhalational ovalbumin challenge, airway hyperreactivity (AHR) to inhaled methacholine was measured by head-out body plethysmography. The animals were subsequently killed to sample bronchoalveolar lavage fluid and lungs.

RESULTS

Sensitized NaCl-treated mice developed marked AHR compared with sham-sensitized animals. This coincided with eosinophilia as well as the amplification of eotaxin and the Th2 cytokines interleukin (IL)-5 and IL-13 in the bronchoalveolar lavage fluid. Treatment of sensitized mice with MALP-2 and IFN-gamma significantly reduced AHR compared with the sensitized, NaCl-treated positive control. Eosinophilia as well as Th2 cytokines were reduced to the levels of unsensitized animals. In contrast, IL-12p70 and neutrophils were markedly increased by treatment with both substances.

CONCLUSION

These data demonstrate the in vivo efficacy of MALP-2 and IFN-gamma to reduce allergic inflammation and AHR in allergic asthma.

The lung cytokine microenvironment influences molecular events in the lymph nodes during Th1 and Th2 respiratory mucosal sensitization to antigen in vivo

Originally defined by their patterns of cytokine production, Th1 and Th2 cells have been described more recently to express other genes differentially as well, at least in vitro. In this study we compared the expression of Th1- and Th2-associated genes directly during in vivo sensitization to ovalbumin (OVA) in Th1- and Th2-polarized models of airways inflammation. Th1-polarized airway inflammation was achieved by the intranasal instillation of adenoviral vectors (Ad) encoding granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin (IL)-12, followed by daily aerosolizations of OVA; instillation of Ad/GM-CSF alone with OVA aerosolization led to Th2-polarized responses. Lymph nodes were obtained at various time-points, RNA extracted, and analysed by real-time quantitative polymerase chain reaction (PCR). Consistent with reports from in vitro and human studies, mice undergoing Th1-polarized inflammation showed preferential expression of the transcription factor t-bet, the chemokines IFN-gamma inducible protein (IP)-10 and macrophage inflammatory protein 1 alpha (MIP-1-alpha), and the chemokine receptor CCR5. In contrast, the transcription factor GATA-3, the chemokines I-309 and thymus and activation regulated chemokine (TARC), and the chemokine receptors CCR3 and CCR4 were preferentially expressed in the Th2 model. Importantly, we also show that Ad/transgene expression remains compartmentalized to the lung after intranasal instillation. Flow cytometric analysis of lung myeloid dendritic cells indicated that B7.1 was expressed more strongly in the Th1 model than in the Th2 model. These studies provide a direct comparison of gene expression in in vivo Th1- and Th2-polarized models, and demonstrate that molecular events in the lymph nodes can be altered fundamentally by cytokine expression at distant mucosal sites.

Regulation of cockroach antigen-induced allergic airway hyperreactivity by the CXCR3 ligand CXCL9

Allergic airway disease is characterized by a robust lymphocytic infiltrate, elaboration of Th2-type inflammatory mediators, pulmonary eosinophil accumulation, and airway hyperreactivity. The CXCR3 ligands, CXCL9 (monokine induced by IFN-gamma) and CXCL10 (IFN-inducible protein, 10 kDa), are IFN-gamma-inducible, Th1-type chemokines. As CXCL10 has been previously shown to participate in the modulation of allergic inflammation, we were interested in investigating the possible role that CXCL9 may play in this inflammatory response. Expression of CXCL9 was primarily identified in airway epithelial cells by immunohistochemical staining. Airway neutralization of CXCL9 at the time of allergen challenge significantly increased airway hyperreactivity, airway eosinophil accumulation, and IL-4 levels in the bronchoalveolar lavage while significantly decreasing airway levels of IL-12. In contrast, introduction of exogenous CXCL9 into the airway at the time of allergen challenge dramatically reduced airway hyper-reactivity and eosinophil accumulation. Moreover, pulmonary levels of IL-4 were significantly reduced, whereas levels of IL-12 were significantly increased, with exogenous CXCL9 treatment. In lymphocytes restimulated with CXCL9 and allergen in vitro, CXCL9 down-regulated IL-4 expression and up-regulated IFN-gamma expression, suggesting that CXCL9 is able to direct activated lymphocytes toward a Th1-type phenotype. Additionally, CXCL9 was shown to inhibit CC chemokine ligand 11-induced eosinophil chemotaxis in in vitro assays. Taken together, our results demonstrate that the CXCR3 ligand CXCL9 is involved in regulation of the allergic response in the lung by regulation of lymphocyte activation and eosinophil recruitment.

Early delayed-type hypersensitivity eosinophil infiltrates depend on T helper 2 cytokines and interferon-gamma via CXCR3 chemokines

We investigated the role of T helper (Th)1- and Th2-type cytokines in delayed-type hypersensitivity to soluble protein antigens elicited early postimmunization. Mice were sensitized by intradermal injection without adjuvants, or subcutaneously with complete Freund's adjuvant, and subsequently ear challenged intradermally. As soon as day 3, antigen-specific eosinophil-rich responses were elicited in wild-type mice, but not in T-cell receptor-alpha-/- mice without adjuvant. Draining lymph node T cells stimulated with antigen secreted interleukin (IL)-4, IL-5 and interferon-gamma (IFN-gamma). IFN-gamma-dependent specific immunoglobulin G (IgG)2a and IL-4-dependent IgG1 were also generated. Delayed-type hypersensitivity ear swelling and local eosinophil recruitment were decreased in IL-5-/-, IL-4-/- and signal transducer and activator of transcription-6 (STAT-6)-/- mice, and with anti-IL-4 treatment of wild-type mice, suggesting Th2 mechanisms. Interestingly, responses were also decreased in IFN-gamma-/- mice, and IFN-gamma protein and the IFN-gamma-inducible CXC chemokine, IP-10, were present in 24-hr ear tissue extracts, suggesting Th1 effects. Finally, ear swelling, total histology and eosinophils were decreased in mice deficient in CXCR3, the chemokine receptor for IP-10. These results suggest that both a Th2-like (IL-5, IL-4 and STAT-6) and a Th1-like (IFN-gamma, IP-10, CXCR3) pathway contribute to eosinophil recruitment in early delayed-type hypersensitivity.

Negative regulation of eosinophil recruitment to the lung by the chemokine monokine induced by IFN-gamma (Mig, CXCL9)

Experimental analysis of allergic airway inflammation (AAI) in animals and humans is associated with coordinate gene induction. Using DNA microarray analysis, we have identified a large panel of AAI signature genes. Unexpectedly, the allergen-challenged lung (a T helper 2 microenvironment) was found to be associated with the expression of T helper 1-associated CXCR3 ligands, monokine induced by IFN-gamma (Mig), and IFN-gamma-inducible protein of 10 kDa (IP-10). Here we report that Mig functions as a negative regulator of murine eosinophils. Whereas Mig was not able to induce chemotaxis of eosinophils, pretreatment with Mig induced a dose-dependent inhibition of chemoattractant-induced eosinophil transmigration in vitro. Moreover, i.v. administration of low doses of Mig ( approximately 10-30 microg/kg) induced strong and specific dose-dependent inhibition of chemokine-, IL-13-, and allergen-induced eosinophil recruitment and, conversely, neutralization of Mig before allergen challenge increased airway eosinophilia. Importantly, Mig also inhibited a CCR3-mediated functional response in eosinophils. These results indicate that the ultimate distribution and function of inflammatory cells within the allergic lung is dictated by a balance between positively and negatively regulatory chemokines. The identification of a naturally occurring eosinophil inhibitory chemokine pathway in vivo provides a strategic basis for future therapeutic consideration.

Allergic humans are hyporesponsive to a CXCR3 ligand-mediated Th1 immunity-promoting loop

CXCR3 binding chemokine CXCL10 (IP-10) markedly enhances antigen-specific Th1 recall responses in healthy humans, suggesting a role for this pathway in maintenance of clinical tolerance to environmental allergens as well as a potential therapeutic role for CXCR3 ligands in re-balancing the Th2-dominated responses that underlie generation and maintenance of allergic disorders. Here, we investigated the capacity of CXCR3 ligands to modulate allergen-driven IFNgamma production by healthy and allergic individuals characterized by Th1 and Th2 immunity-dominated allergen specific responses, respectively. Exogenous CXCR3 ligands up-regulated antigen-dependent IFNgamma production from healthy individuals' peripheral blood mononuclear cells up to 120-fold, a response neutralized by anti-CXCR3 treatment and not emulated by CCR5 ligands. In contrast, allergic individuals were strikingly hypo-responsive to CXCR3 ligands (P=0.0004). Chemokine-enhanced IFNgamma production correlated with T cell CXCR3 expression (r=0.736, P=0.0001) in vivo and was independent of Th2 cytokine levels. These findings demonstrate that CXCR3-ligation preferentially augments ongoing Th1 over Th2 responses and suggest that reduced capacity of allergic individuals to respond to CXCR3 ligands promotes the maintenance of human allergic disorders.

Early high expression of IP-10 in F344 rats resistant to Sendai virus-induced airway injury

Weanling F344 and BN rats differ markedly in their susceptibility to Sendai virus-induced airway injury. Early gene expression that controls their differences in susceptibility remains poorly understood. In this study we combined suppressive subtractive hybridization and cDNA library array hybridization to identify genes differentially expressed in virus-susceptible BN and virus-resistant F344 rats during the first 3 days after inoculation. Differential expression of selected clones was further verified by quantitative RT-PCR. Seven virus-induced gene segments were identified. Of them, interferon-gamma-inducible protein 10 (IP-10), Mx1, and guanylate-binding protein-2 mRNA abundance in infected F344 rats was 201.5, 188.2, and 281.7% higher, respectively, than that of infected BN rats at 2 days after inoculation. In situ hybridization indicated that virus-induced IP-10 was expressed mainly in airway epithelial cells of F344 rats. Sendai virus infection can directly induce IP-10 expression in rat tracheal epithelial cells in vitro. IP-10 early high expression might contribute to the resistance to virus-induced airway disease in F344 rats by promoting Th1 responses and increasing antiviral activity.

The B7 family member B7-H3 preferentially down-regulates T helper type 1-mediated immune responses

We investigated the in vivo function of the B7 family member B7-H3 (also known as B7RP-2) by gene targeting. B7-H3 inhibited T cell proliferation mediated by antibody to T cell receptor or allogeneic antigen-presenting cells. B7-H3-deficient mice developed more severe airway inflammation than did wild-type mice in conditions in which T helper cells differentiated toward type 1 (T(H)1) rather than type 2 (T(H)2). B7-H3 expression was consistently enhanced by interferon-gamma but suppressed by interleukin 4 in dendritic cells. B7-H3-deficient mice developed experimental autoimmune encephalomyelitis several days earlier than their wild-type littermates, and accumulated higher concentrations of autoantibodies to DNA. Thus, B7-H3 is a negative regulator that preferentially affects T(H)1 responses.

Differential role of IFN-gamma-inducible protein 10 kDa in a cockroach antigen-induced model of allergic airway hyperreactivity: systemic versus local effects

The ability of IFN-gamma to antagonize established Th2 type allergic responses is well documented. To investigate the role of IFN-gamma-inducible protein 10 kDa (IP10) in the allergic response, we chose to investigate the effect of IP10 neutralization on an established Th2 response. Systemic neutralization of IP10 at the time of allergen challenge increased airway hyperreactivity as well as airway eosinophil accumulation. Interestingly, IFN-gamma levels were markedly reduced in both the lung and peripheral lymph node following IP10 neutralization. Furthermore, the number of CXCR3(+)CD4(+) T cells was decreased in the peripheral lymph node following neutralization of IP10. Introduction of exogenous IP10 into the airway at the time of allergen challenge also dramatically increased eosinophil accumulation in the airway. Protein levels of IL-4, IL-5, and IL-13 were significantly increased in the lung following exogenous airway administration of IP10 with allergen. Interestingly, airway hyperreactivity was significantly decreased at early time points following concurrent IP10 and allergen challenge but rebounded at 24 and 48 h post allergen challenge. Although IP10 may initially be acting locally to dampen the allergic response, its ability to recruit eosinophils may ultimately supersede any immunomodulatory effect it may have in an established allergic response. These results suggest that while systemic levels of IP10 are beneficial in controlling the allergic response, possibly by regulating cellular trafficking in the lymph node, local administration of exogenous IP10 into an established allergic response may be detrimental.

Increased IFN-gamma protein in bronchoalveolar lavage fluid of anti-IP-10 antibody-treated F344 rats following Sendai viral infection

A previous study showed that virus-resistant F344 rats had higher levels of interferon-gamma (IFN-gamma)-inducible protein 10 (IP-10) than did virus-susceptible BN rats early after Sendai viral infection. The initial goal of this study was to determine if an early high expression of IP-10 in F344 rats contributes to their resistance to virus-induced airway injury. Infected F344 rats were treated with anti-IP-10 rabbit serum or normal rabbit serum. Results indicated that blocking of IP-10 protein did not significantly change the resistance of F344 rats. However, we observed that neutralization of IP-10 increased IFN-gamma protein in bronchoalveolar lavage (BAL) fluid of F344 rats 7 days after inoculation compared with rats that received normal rabbit serum. The pulmonary IFN-gamma mRNA abundance remained comparable. This effect was not caused by fluctuation of the viral titer in the lung. This interesting phenomenon suggests that expression of IFN-gamma protein can be modulated by treatment with anti-IP-10 antibody at the posttranscriptional or translational level in this model.

Treatment of established asthma in a murine model using CpG oligodeoxynucleotides

Allergen immunotherapy is an effective but underutilized treatment for atopic asthma. We have previously demonstrated that CpG oligodeoxynucleotides (CpG ODN) can prevent the development of a murine model of asthma. In the current study, we evaluated the role of CpG ODN in the treatment of established eosinophilic airway inflammation and bronchial hyperreactivity in a murine model of asthma. In this model, mice with established ovalbumin (OVA)-induced airway disease were given a course of immunotherapy (using low doses of OVA) in the presence or absence of CpG ODN. All mice then were rechallenged with experimental allergen. Untreated mice developed marked airway eosinophilia and bronchial hyperresponsiveness, which were significantly reduced by treatment with OVA and CpG. CpG ODN leads to induction of antigen-induced Th1 cytokine responses; successful therapy was associated with induction of the chemokines interferon-gamma-inducible protein-10 and RANTES and suppression of eotaxin. Unlike previous studies, these data demonstrate that the combination of CpG ODN and allergen can effectively reverse established atopic eosinophilic airway disease, at least partially through redirecting a Th2 to a Th1 response.

Role of cytokines and chemokines in bronchial hyperresponsiveness and airway inflammation

Over the last decade there has been an intense interest in the potential role of cytokines and chemokines as important mediators in various atopic diseases, including asthma and the mechanisms by which these mediators regulate airway inflammation and bronchial hyperresponsiveness. This research effort has recently culminated in the publication of clinical studies that have assessed the role of interleukin (IL)-4 [Borish et al., Am J Respir Crit Care Med 160, 1816-1823 (1999)], IL-5 [Leckie et al., Lancet 356, 2144-2148 (2000)], and IL-12 [Bryan et al., Lancet 356, 2149-2153 (2000)] in allergic asthma, and the results have been disappointing. This is not surprising given the pleiotropic role cytokines play in the allergic response confirmed by numerous animal studies providing evidence of functional redundancy. The alternative view is that our current concepts in asthma pathogenesis need significant revision. This review will summarise the evidence for the role of cytokines and chemokines in various aspects of asthma pathophysiology; namely, bronchial hyperresponsiveness, eosinophil recruitment to the airways, mucus secretion, and airway remodelling.

IFN-gamma-inducible protein 10 (CXCL10) contributes to airway hyperreactivity and airway inflammation in a mouse model of asthma

Allergic asthma is an inflammatory disease of the airways characterized by eosinophilic inflammation and airway hyper-reactivity. Cytokines and chemokines specific for Th2-type inflammation predominate in asthma and in animal models of this disease. The role of Th1-type inflammatory mediators in asthma remains controversial. IFN-gamma-inducible protein 10 (IP-10; CXCL10) is an IFN-gamma-inducible chemokine that preferentially attracts activated Th1 lymphocytes. IP-10 is up-regulated in the airways of asthmatics, but its function in asthma is unclear. To investigate the role of IP-10 in allergic airway disease, we examined the expression of IP-10 in a murine model of asthma and the effects of overexpression and deletion of IP-10 in this model using IP-10-transgenic and IP-10-deficient mice. Our experiments demonstrate that IP-10 is up-regulated in the lung after allergen challenge. Mice that overexpress IP-10 in the lung exhibited significantly increased airway hyperreactivity, eosinophilia, IL-4 levels, and CD8(+) lymphocyte recruitment compared with wild-type controls. In addition, there was an increase in the percentage of IL-4-secreting T lymphocytes in the lungs of IP-10-transgenic mice. In contrast, mice deficient in IP-10 demonstrated the opposite results compared with wild-type controls, with a significant reduction in these measures of Th2-type allergic airway inflammation. Our results demonstrate that IP-10, a Th1-type chemokine, is up-regulated in allergic pulmonary inflammation and that this contributes to the airway hyperreactivity and Th2-type inflammation seen in this model of asthma.

CXCR2 is necessary for the development and persistence of chronic fungal asthma in mice

The role of CXCR during allergic airway and asthmatic diseases is yet to be fully characterized. Therefore, the present study addressed the role of CXCR2 during Aspergillus fumigatus-induced asthma. Mice deficient in CXCR2 (CXCR2-/-) and wild-type counterparts (CXCR2+/+) were sensitized to A. fumigatus Ags and challenged with A. fumigatus conidia, and the resulting allergic airway disease was monitored for up to 37 days. At days 3 and 7 after conidia, CXCR2-/- mice exhibited significantly greater methacholine-induced airway hyperreactivity than did CXCR2+/+ mice. In contrast, CXCR2-deficient mice exhibited significantly less airway hyperresponsiveness than the wild-type control groups at days 14 and 37 after conidia. At all times after conidia, whole lung levels of IL-4, IL-5, and eotaxin/CC chemokine ligand 11 were significantly lower in CXCR2-/- mice than in the wild-type controls. Eosinophil and T cell, but not neutrophil, recruitment into the airways of A. fumigatus-sensitized CXCR2-/- mice was significantly impaired compared with wild-type controls at all times after the conidia challenge. Whole lung levels of IFN-gamma, inflammatory protein-10/CXC ligand (CXCL) 10, and monokine induced by IFN-gamma (MIG)/CXCL9 were significantly increased in CXCR2-/- mice compared with CXCR2+/+ mice at various times after conidia. Interestingly, at day 3 after conidia, neutrophil recruitment and airway hyperresponsiveness in CXCR2-/- mice was mediated by inflammatory protein-10/CXCL10 and, to a lesser degree, MIG/CXCL9. Taken together, these data suggest that CXCR2 contributes to the persistence of asthmatic disease due to A. fumigatus.