Effects of oral steroids on blood CXCR3+ and CCR4+ T cells in patients with bronchial asthma

Differential expression of chemokine receptors on monocytes in TB and HIV

In the present study, we defined multiple chemokine receptors expressed by classical, intermediate and non-classical monocyte subsets in TB, HIV and TB/HIV co-infection and associate it with the perturbation of monocyte subsets due to the diseases. Peripheral blood mononuclear cells from TB+ (n = 34), HIV+ (n = 35), TB + HIV+ (n = 12), as well as TB-HIV- healthy controls (n = 39), were tested for monocyte phenotyping by flow cytometry. Frequencies of intermediate and non-classical monocytes were significantly higher in TB and/or HIV disease relative to healthy controls. CCR2 and CX3CR1 were significantly higher on monocytes in TB disease, whereas CCR4 and CCR5 were present at higher levels in HIV disease. TB/HIV co-infected patients exhibited CCR2, CCR5 and CX3CR1 levels intermediate to TB and HIV subjects, while CCR4 was at a higher level than HIV. Despite the increase in the expression of chemokine receptors due to disease conditions, chemokine receptors maintained their original expression pattern on monocyte subsets. Our data provided new insight into the disease-specific but not monocyte subsets-specific modulation of chemokine receptors in TB and HIV.

Chronic Allergen Challenge Induces Corticosteroid Insensitivity With Persistent Airway Remodeling and Type 2 Inflammation

Type 2-high severe asthma is described as a distinct endotype with Th2 inflammation, high eosinophil lung infiltration, impaired lung function, and reduced corticosteroid sensitivity. While the inflammatory milieu is similar to mild asthma, patients with type 2-high severe asthma likely have underlying mechanisms that sustain asthma pathophysiology despite corticosteroid treatments. Acute and chronic allergen models induce robust type 2 inflammatory responses, however differences in corticosteroid sensitivity remains poorly understood. In the present study, we sensitized and challenged mice with ovalbumin (OVA; acute model) or mixed allergens (MA; chronic model). Corticosteroid sensitivity was assessed by administering vehicle, 1, or 3 mg/kg fluticasone propionate (FP) and examining key asthmatic features such as airway inflammation, remodeling, hyperresponsiveness, and antioxidant capacity. Both acute and chronic allergen exposure exhibited enhanced AHR, immune cell infiltration, airway inflammation, and remodeling, but corticosteroids were unable to fully alleviate inflammation, AHR, and airway smooth muscle mass in MA-challenged mice. While there were no differences in antioxidant capacity, persistent IL-4+ Th2 cell population suggests the MA model induces type 2 inflammation that is insensitive to corticosteroids. Our data indicate that chronic allergen exposure is associated with more persistent type 2 immune responses and corticosteroid insensitivity. Understanding differences between acute and chronic allergen models could unlock underlying mechanisms related to type 2-high severe asthma.

The effects of oral corticosteroids on lung function, type-2 biomarkers and patient-reported outcomes in stable asthma: A systematic review and meta-analysis

BACKGROUND

Several studies have investigated the physiological effect of OCS in stable asthma, however these have included heterogeneous populations and outcomes. This paper is the first to combine their results.

METHODS

We searched Medline, Embase and Web of Science databases for studies reporting the impact of OCS on FEV₁, FVC, blood eosinophils, fractional exhaled nitric oxide (FeNO), Asthma Control Questionnaire (ACQ) score or Asthma Quality Of Life Questionnaire (AQLQ) score in stable asthma. We extracted data on the correlates of OCS response.

RESULTS

61 studies, comprising 1608 patients, were included. FEV₁ was improved by 9% (95% CI: 7, 11). There were stronger increases in FEV₁ among those with a mean baseline FEV₁<60% predicted (19%, 95% CI: 13, 24). Despite these improvements, substantial residual impairment remained after treatment. Blood eosinophils were reduced by 76% (95% CI: 63, 88) with larger decreases in studies of corticosteroid-naïve patients (93%, 95% CI: 73,100). Sputum eosinophils were reduced by 89% (95% CI: 79, 98) while FeNO was decreased by 35% (95% CI: 28, 41). ACQ scores were reduced by 20% (95% CI: 11, 29). Patients with higher baseline lung function impairment, sputum eosinophils, blood eosinophils and FeNO had improved OCS response.

INTERPRETATION

OCS consistently improves lung function, reduces markers of type-2 inflammation, and alleviates asthma symptoms. However, substantial residual impairment remained following treatment and mean improvements were below the minimally important clinically difference. Patients with increased markers of type-2 inflammation are more responsive to treatment, suggesting these should be used to better target OCS use.

Effects of anti-allergic drugs on T cell-mediated nasal hyperresponsiveness in a murine model of allergic rhinitis

BACKGROUND

We have recently demonstrated that T cell-mediated nasal hyperresponsiveness (NHR) is a representative pathophysiological feature of allergic rhinitis (AR). Although several anti-allergic drugs are used for the treatment of AR, the efficacy of these drugs on T cell-mediated NHR have not been elucidated. In these studies we investigated the effects of dexamethasone (Dex), montelukast (Mk), and chlorpheniramine (Chl) on NHR in antigen-immunized and antigen-specific Th2 cell-transferred mice.

METHODS

OVA-immunized BALB/c mice were treated with Dex, Mk, or Chl and challenged intranasally with OVA. We then assessed NHR, the number of inflammatory cells in the nasal lavage fluid (NALF), mRNA expression of Th2 cytokines in the nasal tissue, the population of CD3⁺CD4⁺ cells in the nasal lymphoid tissue (NALT), and antigen-specific serum IgE and IgG levels. Antigen-induced NHR and changes in antigen-specific T cells in the NALT were investigated in OVA-specific Th2 cell-transferred mice.

RESULTS

Dex significantly suppressed antigen-induced NHR, inflammatory cell infiltration, and IL-4, IL-5, IL-6, and IL-13 expression in immunized mice. Chl was completely ineffective, and only IL-13 expression was suppressed by Mk. None of these drugs affected IgE and IgG production. Antigen-induced NHR and the increase in antigen-specific T cells in the NALT of Th2 cell-transferred mice were inhibited by Dex, but not by Mk or Chl.

CONCLUSIONS

Steroids are effective for the reduction of NHR in AR by suppressing the accumulation of inflammatory cells, especially antigen-specific T cells.

Clinical implications of CD4+ T cell subsets in adult atopic asthma patients

Background

T cells play a central role in chronic inflammation in asthma. However, the roles of individual subsets of T cells in the pathology of asthma in patients remain to be better understood.

Methods

We investigated the potential signatures of T cell subset phenotypes in asthma using fresh whole blood from adult atopic asthma patients (n = 43) and non-asthmatic control subjects (n = 22). We further assessed their potential clinical implications by correlating asthma severity.

Results

We report four major features of CD4⁺ T cells in the blood of atopic asthma patients. First, patients had a profound increase of CCR7⁺ memory CD4⁺ T cells, but not CCR7⁻ memory CD4⁺ T cells. Second, an increase in CCR4⁺ CD4⁺ T cells in patients was mainly attributed to the increase of CCR7⁺ memory CD4⁺ T cells. Accordingly, the frequency of CCR4⁺CCR7⁺ memory CD4⁺ T cells correlated with asthma severity. Current common asthma therapeutics (including corticosteroids) were not able to affect the frequency of CCR4⁺CCR7⁺ memory CD4⁺ T cell subsets. Third, patients had an increase of Tregs, as assessed by measuring CD25, Foxp3, IL-10 and CTLA-4 expression. However, asthma severity was inversely correlated only with the frequency of CTLA-4⁺ CD4⁺ T cells. Lastly, patients and control subjects have similar frequencies of CD4⁺ T cells that express CCR5, CCR6, CXCR3, CXCR5, CD11a, or α4 integrin. However, the frequency of α4⁺ CD4⁺ T cells in patients correlated with asthma severity.

Conclusions

CCR4⁺CCR7⁺ memory, but not CCR4⁺CCR7⁻ memory, α4⁺, and CTLA4⁺ CD4⁺ T cells in patients show significant clinical implications in atopic asthma. Current common therapeutics cannot alter the frequency of such CD4⁺ T cell subsets in adult atopic asthma patients.

Electronic supplementary material

The online version of this article (10.1186/s13223-018-0231-3) contains supplementary material, which is available to authorized users.

Chemokine receptors expression on CD3+ blood cells in bronchial asthma

PURPOSE

Chemokines and their receptors participate in pathomechanism of bronchial asthma. The aim of the study was to analyze the pattern of chemokine receptor expression on T cells in severe asthmatics and to compare to mild-to-moderate patients and controls.

MATERIAL/METHODS

Flow cytometric analysis of CXCR1, CXCR2, CXCR3, CCR3, CCR4, CCR5, CCR7, CCR8 expression on CD3(+)CD8(-) and CD3(+)CD8(+) cells was performed in patients with different severity of chronic asthma and in controls.

RESULTS

Percentages of CD3(+)CD8(+) cells expressing CXCR1 were significantly lower in severe asthmatic than in mild-to-moderate asthmatics and in controls. Percentages of CD3(+)CD8(+) cells expressing CCR7 were significantly lower in the severe asthma group than in control group. Percentages of CD3(+)CD8(-) cells expressing CXCR1, CXCR2 and CCR8 were significantly lower in the severe asthma group than in mild-to-moderate asthmatics and in controls. The number of cells CD3(+)CD8(-) and CD3(+)CD8(+) expressing of CXCR1 was significantly lower in the group of patients using more than 800μg of budesonide daily than in the group of patients using less than 400μg of budesonide. Percentages of CD3(+)CD8(-) cells expressing CXCR3, CCR4 and CCR5 were visibly higher (not significantly) in chronic mild-to-moderate asthma than in healthy controls and severe asthmatics.

CONCLUSIONS

These results may indicate impairment of some chemokine expression on T cells in severe asthma patients. Moreover participation of both chemokine receptors related to Th1 and Th2 responses in mild-to-moderate asthma and attenuation of these responses in severe asthma has been suggested.

Abnormal chemokine receptor profile on circulating T lymphocytes from nonallergic asthma patients

BACKGROUND

T lymphocytes are involved in the pathogenesis of nonallergic asthma. The objective of this study was to characterize the subset distribution and pattern of chemokine receptor expression in circulating T lymphocyte subsets from nonallergic asthma patients.

METHODS

Forty stable nonallergic asthma patients and 16 sex- and age-matched healthy donors were studied. Twelve patients did not receive inhaled steroids (untreated patients), 16 received 50-500 μg b.i.d. of inhaled fluticasone propionate (FP) (standard-dose patients), and 12 received over 500 μg b.i.d. of inhaled FP (high-dose patients) for at least 12 months prior to the beginning of this study and were clinically well controlled. Flow cytometry was performed using a panel of monoclonal antibodies (4 colors).

RESULTS

Nonallergic asthma patients treated with high doses of inhaled FP showed a significant reduction in the percentages of CD3+ T lymphocytes compared to healthy controls. Untreated patients showed a significant increase in CCR6 expression in CD8+CD25+ and CD8+CD25+bright T cells compared to healthy controls. The results were similar for CXCR3 and CCR5 expression. In patients treated with standard doses of FP, CCR5 expression was significantly increased in CD3+ T lymphocytes relative to healthy controls.

CONCLUSIONS

The different groups of clinically stable nonallergic asthmatic patients showed distinct patterns of alterations in subset distribution as well as CCR6, CXCR3, and CCR5 expression on circulating T lymphocytes. .

Expression of CXCR3 and its ligands CXCL9, -10 and -11 in paediatric opsoclonus-myoclonus syndrome

Opsoclonus-myoclonus syndrome (OMS) is a neuroinflammatory disorder associated with remote cancer. To understand more clearly the role of inflammatory mediators, the concentration of CXCR3 ligands CXCL10, CXCL9 and CXCL11 was measured in 245 children with OMS and 81 paediatric controls using enzyme-linked immunosorbent assay (ELISA), and CXCR3 expression on CD4(+) T cells was measured by flow cytometry. Mean cerebrospinal fluid (CSF) CXCL10 was 2·7-fold higher in untreated OMS than controls. Intrathecal production was demonstrated by significantly different CXCL10 CSF : serum ratios. The dichotomized 'high' CSF CXCL10 group had higher CSF leucocyte count (P = 0·0007) and B cell activating factor (BAFF) and CXCL13 concentrations (P < 0·0001). CSF CXCL10 did not correlate with clinical severity or relapse using grouped data, although it did in some patients. Among seven types of immunotherapy, including rituximab or chemotherapy, only adrenocorticotrophic hormone (ACTH) monotherapy showed reduced CSF CXCL10, but prospective longitudinal studies of ACTH combination therapies indicated no reduction in CXCL10 despite clinical improvement (P < 0·0001). CXCL10 concentrations were 11-fold higher in CSF and twofold higher in serum by multiplexed fluorescent bead-based immunoassay than enzyme-linked immunosorbent assay, but the two correlated (r = 0·7 and 0·83). In serum, no group differences for CXCL9 or CXCL11 were found. CXCR3 expression on CD4(+) T cells was fivefold higher in those from CSF than blood, but was not increased in OMS or altered by conventional immunotherapy. These data suggest alternative roles for CXCL10 in OMS. Over-expression of CXCL10 was not reduced by clinical immunotherapies as a whole, indicating the need for better therapeutic approaches.

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.

Attenuation of antigen-induced airway hyperresponsiveness and inflammation in CXCR3 knockout mice

Background

CD8+ T cells participate in airway hyperresponsiveness (AHR) and allergic pulmonary inflammation that are characteristics of asthma. CXCL10 by binding to CXCR3 expressed preferentially on activated CD8+ T cells, attracts T cells homing to the lung. We studied the contribution and limitation of CXCR3 to AHR and airway inflammation induced by ovalbumin (OVA) using CXCR3 knockout (KO) mice.

Methods

Mice were sensitized and challenged with OVA. Lung histopathological changes, AHR, cellular composition and levels of inflammatory mediators in bronchoalveolar lavage (BAL) fluid, and lungs at mRNA and protein levels, were compared between CXCR3 KO mice and wild type (WT) mice.

Results

Compared with the WT controls, CXCR3 KO mice showed less OVA-induced infiltration of inflammatory cells around airways and vessels, and less mucus production. CXCR3 KO mice failed to develop significant AHR. They also demonstrated significantly fewer CD8+ T and CD4+ T cells in BAL fluid, lower levels of TNFα and IL-4 in lung tissue measured by real-time RT-PCR and in BAL fluid by ELISA, with significant elevation of IFNγ mRNA and protein expression levels.

Conclusions

We conclude that CXCR3 is crucial for AHR and airway inflammation by promoting recruitment of more CD8+ T cells, as well as CD4+ T cells, and initiating release of proinflammatory mediators following OVA sensitization and challenge. CXCR3 may represent a novel therapeutic target for asthma.

Changes in helper lymphocyte chemokine receptor expression and elevation of IP-10 during acute respiratory syncytial virus infection in infants

It is known that lymphopenia caused by apoptosis may occur during severe respiratory syncytial virus (RSV) infection. However, further evidence about how T-cell subsets may be affected in infants during severe RSV bronchiolitis is needed to understand the mechanisms through which immunological memory may be altered. There is increasingly convincing evidence that RSV may be associated with the development of atopy and asthma. Surrogates of Th1, Th2 and regulatory T-lymphocyte populations were measured in blood from children with acute RSV bronchiolitis and in convalescence using the cell surface receptors CXCR3, CCR4 and CD25, respectively. Samples were also obtained from healthy age-matched controls. Plasma levels of the chemokines interferon-γ inducible protein-10 (IP-10) and thymus and activation-regulated chemokine (TARC), which are known ligands for CXCR3 and CCR4, were also measured. Free plasma DNA was measured using quantitative PCR. CXCR3-positive cells were significantly decreased during acute infection (p = 0.013), while CCR4 and CD25 T-cell populations were unchanged. Plasma levels of IP-10 were markedly elevated in acute infection (p = 0.001). Convalescent samples were not significantly different to control samples for lymphocyte phenotypes or plasma chemokines. Elevated free plasma DNA was detected during acute infection compared with convalescence and controls. A profound reduction in the Th1, but not Th2, and CD25-positive lymphocyte populations associated with exaggerated IP-10 production occurs in severe RSV bronchiolitis. Free DNA is detectable in plasma. This may allow significant alterations in the generation of T-cell memory.

Chemokine receptor 4 plays a key role in T cell recruitment into the airways of asthmatic patients

T lymphocytes of the Th2 type are central orchestrators of airway inflammation in asthma. The mechanisms that regulate their accumulation in the asthmatic airways remains poorly understood. We tested the hypothesis that CCR4, preferentially expressed on T lymphocytes of the Th2 type, plays a critical role in this process. We enumerated by flow cytometry the CCR4-expressing T cells from blood, induced sputum, and biopsy samples of patients with asthma and control subjects. We showed a positive correlation between the numbers of peripheral blood CCR4+ T cells and asthma severity, provided evidence of preferential accumulation of CCR4+ T cells in asthmatic airways, and demonstrated that CCR4+ but not CCR4- cells from patients with asthma produce Th2 cytokines. Explanted airway mucosal biopsy specimens, acquired by bronchoscopy from subjects with asthma, were challenged with allergen and the explant supernatants assayed for T cell chemotactic activity. Allergen-induced ex vivo production of the CCR4 ligand, CCL17 was raised in explants from patients with asthma when compared with healthy controls. Using chemotaxis assays, we showed that the T cell chemotactic activity generated by bronchial explants can be blocked with a selective CCR4 antagonist or by depleting CCR4+ cells from responder cells. These results provide evidence that CCR4 might play a role in allergen-driven Th2 cell accumulation in asthmatic airways. Targeting this chemokine receptor in patients with asthma might reduce Th2 cell-driven airway inflammation; therefore, CCR4 antagonists could be an effective new therapy for asthma. This study also provides wider proof of concept for using tissue explants to study immunomodulatory drugs for asthma.

Increased granulocyte-colony stimulating factor (G-CSF) and granulocyte-macrophage colony stimulating factor (GM-CSF) levels in BAL fluid from patients with sulfur mustard gas-induced pulmonary fibrosis

The objective of this article was to show the role of cytokines in the pathogenesis of pulmonary fibrosis due to sulfur mustard gas inhalation. Eighteen veterans with mustard gas-induced pulmonary fibrosis and 18 normal patients were used as controls. Bronchoalveolar larvage (BAL) and analyses of BAL fluids for cellular and cytokine levels were performed. There was a significant difference in granulocyte colony stimulating factor (G-CSF) level in the BAL fluid of patients and the controls (p < 0.0001). Granulocyte-macrophage colony stimulating pulmonary fibrosis (GM-CSF) BAL levels were significantly increased in patients with pulmonary fibrosis (PF) in comparison with controls (p < 0.0001). Patients with PF have highly significant increases in IL-8 level compared to controls (87.94 +/- 59.63 vs. 8.66 +/- 6.97 g/mL(1); p < 0.0001) as well. IL-8 and G-CSF levels in BAL fluid correlate only with the percentage and the absolute number of neutrophils of the BAL fluid in patients with PF (p = 0.02/p = 0.01; p = 0.01/p = 0.01; respectively). A significant correlation was found between GM-CSF BAL fluid level and the percentage and the absolute number of the BAL fluid eosinophils (p = 0.04 and p = 0.03). Neutrophils alveolitis, the presence of eosinophils, and higher concentrations of interleukin-8, G-CSF, and GM-CSF in BAL fluid are associated with the development of fibrosis in sulfur mustard victims.

Asthma severity is associated with an increase in both blood CXCR3+ and CCR4+ T cells

OBJECTIVES

A predominance of type 2 helper T cells (Th2) in the bronchoalveolar space and peripheral blood is a well-accepted feature of bronchial asthma. However, the relationship between peripheral blood Th2 cells and asthma severity has not been thoroughly investigated.

METHODS

As Th1 cells predominantly express the chemokine receptor CXCR3 and Th2 cells express CCR4, we assessed the distribution of peripheral blood CXCR3+ and CCR4+ lymphocytes using flow cytometry in 186 patients with asthma and 75 normal subjects.

RESULTS

The proportion of CXCR3+/CD45RO+ cells in CD4+ T cells increased as the severity of asthma increased. The percentage of CCR4+/CD45RO+ cells in CD4+ T cells were elevated in mild to severe asthma patients compared with controls. However, there was no significant difference in CCR4+/CD45RO+ cells between the mild to severe asthma patients. There was no relationship between the patient's age and the numbers of CXCR3+ or CCR4+ T cells. The percentage of CCR4+ cells in CD45RO+/CD4+ T cells correlated with the levels of total serum IgE (r = 0.630, P < 0.0001).

CONCLUSIONS

The proportion of CCR4+ cells in blood memory helper T cells may be increased in patients with asthma and is associated with the level of serum IgE, but severity of asthma is also associated with the increase of blood CXCR3+ cells in memory helper T cells.

Role of the chemokine receptors CXCR3 and CCR4 in human pulmonary fibrosis

RATIONALE

The chemokine receptors CXCR3 and CCR4 have recently been described as playing a pivotal role in the mouse model of bleomycin-induced fibrosis.

OBJECTIVES

To evaluate the role of these receptors in human idiopathic pulmonary fibrosis (IPF).

METHODS

We studied 57 patients: 18 with IPF, 17 with non-IPF (nIPF), 12 with sarcoidosis, and 10 healthy control subjects.

MEASUREMENTS

We evaluated the expression of CXCR3 and CCR4 in blood and bronchoalveolar lavage (BAL) T lymphocytes by flow cytometry and the chemokine CXCL10, CXCL11 and CCL17 BAL concentration by singular immunoassay.

MAIN RESULTS

Patients with IPF had a significantly lower CXCR3 and a higher CCR4 expression on BAL CD4 T cells compared with the other groups. Among patients with IPF, those treated with corticosteroids exhibited higher CXCR3 and lower CCR4 expression compared with untreated patients. CXCR3 expression correlated with BAL lymphocytes and CCR4 with BAL neutrophils and eosinophils. CXCL10 levels correlated with the expression of CXCR3 on BAL CD4 cells. CXCL11 was undetectable in almost all patients, whereas CCL17 was primarily detectable in patients with IPF. The percentage of BAL CCR4CD4 cells negatively correlated with DL(CO). The changes in the total lung capacity, VC, and of the alveolar-arterial PO2 gradient in patients with IPF and those with nIPF 6 to 12 mo after the first evaluation were associated with CD4CXCR3 percentage on BAL cells.

CONCLUSIONS

We found an imbalance in CXCR3/CCR4 expression on BAL CD4 lymphocytes and reduced CXCL10 BAL levels in patients with IPF, suggesting a pivotal role of these molecules in IPF.

Effects of corticosteroid on the expression of thymus and activation-regulated chemokine in a murine model of allergic asthma

BACKGROUND

Thymus and activation-regulated chemokine (TARC; CCL17) is a lymphocyte-directed CC chemokine that specifically attracts T-helper (Th) 2 cells positive for the CC chemokine receptor 4 (CCR4(+)). Corticosteroids reduce airway inflammation, as reflected by reduced numbers of eosinophils and T cells and reduced expression of cytokines. We investigated TARC production and the inhibitory effects of corticosteroids on TARC expression in a murine model of allergic asthma.

METHODS

BALB/c mice were sensitized by intraperitoneal injection of ovalbumin (OVA) with alum. Once daily for 1 week, mice received injections of dexamethasone or 0.2 ml saline (control), then 1 h later inhaled aerosolized 1% OVA for 30 min. Mice were killed 24 h after OVA challenge for bronchoalveolar lavage and lung tissue examination.

RESULTS

TARC was expressed mainly in the bronchial epithelial cells. Dexamethasone attenuated OVA-induced airway eosinophilia, lymphocyte infiltration, and airway hyperresponsiveness. Dexamethasone also decreased TARC production in the bronchoalveolar lavage fluid and decreased expression of TARC mRNA and TARC protein in lung tissue.

CONCLUSIONS

The corticosteroid dexamethasone inhibits TARC production in a murine model of allergic asthma in vivo. The beneficial effect of corticosteroids in bronchial asthma is due in part to their direct inhibitory effects on TARC production.

Role of CCR4 ligands, CCL17 and CCL22, during Schistosoma mansoni egg-induced pulmonary granuloma formation in mice

Controversy persists pertaining to the role of CCR4 ligands, namely CCL17 (or thymus and activation regulated chemokine; TARC) and CCL22 (or macrophage-derived chemokine; MDC), in Th2-type cytokine-dominated responses in the lung. Accordingly, the present study addressed the relative role of each of these CC chemokines during an evolving pulmonary granulomatous response elicited by the intrapulmonary embolization of live Schistosoma mansoni eggs into S. mansoni-sensitized mice. CCL22 protein expression peaked at day 4, but CCL17 levels were not increased significantly at any time after egg challenge. CCR4 transcript and protein expression were highest at day 8 after egg embolization and CCR4 protein was prominently expressed in macrophages surrounding S. mansoni eggs. Systemic immunoneutralization of CCL22 from the time of egg injection into S. mansoni-sensitized mice for 8 days significantly decreased CCR4 protein expression, the eosinophil content, the overall size of the egg granuloma, and its hydroxyproline content. Whole lung levels of interferon-gamma were also significantly increased at day 8 in anti-CCL22-treated mice. The systemic immunoneutralization of CCL17 had a lesser effect on all of the granuloma parameters listed above, but this antibody treatment significantly decreased granuloma hydroxyproline content to a greater extent than the anti-CCL22 antibody treatment. In addition, the immunoneutralization of CCL17 significantly increased whole lung levels of interleukin (IL)-4, IL-5, IL-13, transforming growth factor-beta, IL-12, and tumor necrosis factor-alpha at day 8 after egg infusion. Thus, these studies demonstrate a major role for CCL22 and a lesser role for CCL17 during an evolving S. mansoni egg granuloma in the lung.

Prostaglandin D2 reinforces Th2 type inflammatory responses of airways to low-dose antigen through bronchial expression of macrophage-derived chemokine

PGD2, a lipid mediator released from mast cells, is known to participate in allergic reactions. However, the mechanism by which PGD2 contributes to such reactions remains unclear. We established a novel experimental model of asthma that permitted direct assessment of the role of PGD2 in airway inflammation. Antigen-sensitized mice were exposed to aerosolized prostaglandin D2 (PGD2) 1 d before challenge with low-dose aerosolized antigen. Not only the numbers of eosinophils, lymphocytes, and macrophages but also the levels of IL-4 and IL-5 in bronchoalveolar lavage fluid were higher in PGD2-pretreated mice than in control mice. The expression of macrophage-derived chemokine (MDC), a chemoattractant for Th2 cells, was greater in PGD2-pretreated mice than in control. Injection of anti-MDC antibody into PGD2-pretreated mice markedly inhibited inflammatory cell infiltration as well as Th2 cyto-kine production after antigen challenge. These results indicate that PGD2 accelerates Th2 type inflammation by induction of MDC. Our results suggest that this mechanism may play a key role in the development of human asthma and that MDC might be a target molecule for therapeutic intervention.

CCR4 is an up-regulated chemokine receptor of peripheral blood memory CD4+ T cells in Crohn's disease

Several chemokine receptors are expressed selectively on the surface of T cells depending on their polarization. The aim of this study was to characterize chemokine receptor expression in peripheral blood memory T cells in Crohn's disease (CD) and ulcerative colitis (UC), and to correlate the expression with disease activity. Peripheral blood mononuclear cells (PBMCs) were obtained from 24 patients with CD, 30 patients with UC, 24 normal controls and 10 disease controls. PBMCs were stained by anti-CCR3, CCR4, CCR5, CXCR3, CD4, CD8, CD45RO and beta 7 integrin, and the expression of the chemokine receptors were determined by flow cytometry. CCR4 expression on memory T cells was significantly lower in UC than in CD or normal controls, and that of memory CD4+ T and beta 7(high) memory CD4+ T cells was significantly higher in CD than in UC or normal controls. CCR4 expression on memory CD4+ T cells exhibited significant positive correlation with disease activity in CD, and this decreased significantly after treatment. Such a decrease was not found in the disease controls. CCR5 and CXCR3 expression on memory CD8+ T cells was significantly lower in CD than in normal controls. CXCR3 expression on beta 7(high) memory CD4+ T and CXCR3 expression on memory CD8+ T cells were lower in UC than in normal controls. These findings suggest that in peripheral blood memory T cells, chemokine receptor expression is different between CD and UC. Enhancement of CCR4 and suppression of CCR5 and CXCR3 seem to be the characteristic chemokine receptor profile in peripheral blood memory T cells of CD.

A potential role for CXCR3 chemokines in the response to ocular HSV infection

Corneal infection with herpes simplex virus (HSV) leads to the recruitment of immune cells to the eye itself, the trigeminal ganglion and the brainstem. In addition, some resident cells in these target tissues are infected by HSV, activated during the inflammatory response or both. Chemokine signaling is an important component of the regulatory circuit governing the host immune response to virus infection. This review discusses chemokine responses in relation to HSV infection of the cornea emphasizing the role of CXCR3 chemokine signaling by the IFN-gamma inducible ligands MIG, IP10 and I-TAC and includes discussion of their potential role in immunopathology in the nervous system.

New asthma targets: recent clinical and preclinical advances

Current asthma therapy is directed at the relief of chronic inflammation or improving lung function through bronchodilation. These approaches treat the overt symptoms of asthma but do not approach underlying causes of the disease. Such therapies have limited efficacy and for a number of patients the disease remains poorly controlled. The short-term future of asthma therapy will probably focus on the treatment of multiple symptoms to provide improved lung function. Long-term approaches to asthma will have to focus on modulation of the mechanisms that are the underlying causes of the various asthmatic pathophysiologies. These targets include a number of TH2-type T-cell-generated cytokines and chemokines, G-protein-coupled receptors, TH2-related transcription factors, neurotrophins and adhesion molecules. Additional new targets and understanding of asthma may also arise from genetic analysis.