Inhaled IL-5 increases concentrations of soluble intracellular adhesion molecule-1 in sputum from atopic asthmatic subjects

Anti-Interleukin-5 Monoclonal Antibodies

Descriptive studies have shown an association between eosinophils, interleukin (IL)-5 and pathophysiological processes in patients with atopic asthma. These observations have led to an interest in the eosinophil as the pathogenic cell responsible for many of the clinical features of asthma including symptoms of wheeze, shortness of breath and cough, along with the physiological events such as airway hyperresponsiveness (AHR) and changes in lung function. IL-5 is one of the key cytokines responsible for eosinopoiesis in the bone marrow, along with recruitment and survival of eosinophils in the tissues. In view of this, IL-5 has been an attractive target for the development of anti-IL-5 monoclonal antibodies, inhibiting its action. The results of preclinical studies are viewed as encouraging. Preclinical development involved studies in mice, guinea-pigs and cynomolgus monkeys, with conflicting results in terms of changes in blood and bronchoalveolar lavage eosinophils, AHR and pulmonary resistance. These may be attributed to interspecies differences and to the different models used. Monoclonal antibodies directed against IL-5 have been used in at least four studies involving patients with asthma. Those preliminary studies have shown clear reductions in both blood and sputum eosinophils but no significant changes in physiological parameters of AHR, the late asthmatic reaction or in lung function or symptoms. As in the animal studies, these results suggest a dissociation between eosinophils, AHR, lung function and symptoms of asthma, which may be explained by the multitude of cells involved in the pathogenesis of asthma.

Systemic and airway inflammation in sleep apnea and obesity: the role of ICAM-1 and IL-8

The recurrent hypoxic stress that characterizes obstructive sleep apnea (OSA) seems to play a role in the increased adherence of neutrophils to endothelial cells as well as in the resulting migration of the former to the inflamed area. Intercellular adhesion molecule 1 (ICAM-1) and interleukin (IL)-8 are markers widely used in OSA studies to investigate inflammation. The aim of this study was to measure ICAM-1 and IL-8 levels in the breath condensate and in the plasma and inflammatory cells in the induced sputum of 12 obese OSA (OO) patients, 10 nonobese OSA (NOO) patients, 10 obese non-OSA (ONO) subjects, and 8 healthy subjects (HS) using a specific enzyme immunoassay (EIA) kit. A significant increase in both plasma and exhaled IL-8 and ICAM concentrations and percentage neutrophils was observed in the induced sputum of obese OSA patients, non-obese OSA patients, and obese non-OSA subjects compared with healthy subjects. However, although these inflammatory markers were found to follow an upward trend in obese OSA patients no difference was observed in both either non-obese OSA patients and obese non-OSA subjects. Finally, a significant positive correlation was found to occur among IL-8, ICAM-1, and sputum neutrophils, as well as across the apnea-hypopnoea index (AHI), TST 90%, body mass index (BMI), and neck circumference. The data obtained confirm the occurrence of an ICAM- and IL-8-mediated neutrophilic airway inflammation in both OSA and obese patients. The degree of inflammation, which seems to worsen in cases of comorbidity (OSA and obesity), is likely to be responsible for the increased risk of developing cardiovascular events observed in these subjects, and therefore, it deserves to be elucidated even more.

Soluble intercellular adhesion molecule-1 and E-selectin in patients with asthma exacerbation

Soluble intercellular adhesion molecule-1 (sICAM-1) and soluble E-selectin (sE-selectin) are important factors in immunological processes of inflammatory cell buildup in target tissues. Studies have suggested that these molecules could be important markers of inflammatory diseases. This study was undertaken to assess the levels of sICAM-1 and sE-selectin during an acute attack of asthma in adults and children and to establish normal values (95th percentile) in healthy control subjects. We analyzed serum levels of ICAM-1 and E-selectin in 120 children and adults obtained during an acute attack of asthma: 40 with severe and 80 with moderately severe attack, and 50 healthy subjects as controls by ELISA (enzyme linked immunosorbent assay). sICAM-1 from patients with asthma was significantly higher than healthy controls (P < 0.001) but not for sE-selectin (P = 0.778). Significant differences were observed in moderately severe attack versus controls and severe attack of asthma for sICAM-1. With 95th percentile levels as cutoff for normal values (sICAM-1 = 585.08 ng/ml, sE-selectin = 160.87 ng/ml), it was observed that 88.3% of subjects (sICAM-1) and 98.5% of subjects (sE-selectin) with an acute attack of asthma had levels within the normal range. Although mean serum levels of sICAM-1 are higher in asthmatics than normal controls, it may be necessary to establish individual baseline values for serial estimation to evaluate their clinical relevance.

CD4CD25 regulatory T lymphocytes in allergy and asthma

Allergic asthma is characterized by airway hyper-responsiveness and chronic mucosal inflammation mediated by CD4(+) Th2 lymphocytes. Regulatory CD4(+)CD25(+) T cells are important components of the homeostasis of the immune system, as impaired CD4(+)CD25(+) T cell activity can cause autoimmune diseases and allergy. The mechanism of suppression by CD4(+)CD25(+) T cells remains controversial; different in vivo and in vitro studies raise possible roles for the immunosuppressive cytokines interleukin-10 and transforming growth factor-beta, forkhead transcription factor Foxp3, glucocorticoid-induced tumor necrosis factor receptor, cytotoxic lymphocyte associated antigen-4, 4-1BB costimulator receptor, a CD4-related molecule LAG-3, and neuropilin-1. Current data suggest that Th2 responses to allergens are normally suppressed by CD4(+)CD25(+) T cells. Suppression by CD4(+)CD25(+) T cells is decreased in allergic individuals. Furthermore, CD4(+)CD25(+) T cells play a key role in regulating airway eosinophilic inflammation. The immunomodulatory properties of CD4(+)CD25(+) T cells do extend to Th2 responses, most notably by limiting the development of a proinflammatory CD4(+) Th2 phenotype characterized by reduced cytokine production. An understanding of the roles of CD4(+)CD25(+) T cells in vivo could provide better insight into the design of novel approaches to modulate the chronic airway inflammatory reaction evident in bronchial asthma.

A single nasal allergen challenge increases induced sputum inflammatory markers in non-asthmatic subjects with seasonal allergic rhinitis: correlation with plasma interleukin-5

BACKGROUND

Seasonal allergic rhinitis (SAR) is a risk factor for asthma in affected individuals. Nasal allergic inflammation enhances bone-marrow eosinophil production, mainly via IL-5, and rhinitis patients have increased airway inflammation during the pollen season.

OBJECTIVE

To assess the impact of nasal allergy on sputum inflammatory markers.

METHODS

In an open-labelled, randomized, placebo-controlled cross-over study with 16 non-asthmatic SAR patients (median age 25 years, 56% males), the effect of a single nasal allergen challenge performed out of season on induced sputum inflammatory parameters was evaluated. SAR patients were identified by history, skin-prick test and specific IgE. All patients had normal lung function/bronchial hyper-responsiveness out of season and a negative asthma/wheezing history. Sputum cells and supernatant levels of ECP, sICAM, IL-5 and IL-10, and plasma levels of IL-5 and ECP, were measured before and 24 h after nasal allergen challenge. After a washout period of at least 4 weeks, the procedure was repeated with placebo challenge (diluent).

RESULTS

Nasal allergen challenge led to an increase in sputum ECP (pre = 60 +/- 12, post = 212 +/- 63 micro g/L, P = 0.02 vs. placebo), and sICAM (4.8 +/- 2.7 to 6.5 +/- 2.9 ng/mL, P = 0.02 vs. placebo), whereas IL-10 decreased after provocation (44 +/- 11 to 29 +/- 6 pg/mL, P = 0.06 vs. placebo). Sputum IL-5 was undetectable in all patients. The absolute number of blood and sputum eosinophils did not change significantly after allergen or placebo challenge (P > 0.07, both comparisons). Plasma levels of IL-5 increased after allergen challenge (8.7 +/- 2.9 to 14.5 +/- 3.9 pg/mL, P = 0.001), and the increase in plasma IL-5 was positively correlated with the rise in sputum ECP in a subgroup of 'responders' (n = 12, r = 0.71, P = 0.01).

CONCLUSIONS

A single nasal allergen challenge in SAR patients increased markers of allergic inflammation in the lower respiratory tract, possibly via pronounced activation of inflammatory cells through circulating immediate-type reaction cytokines like IL-5. These findings may provide additional explanatory data for the high susceptibility of SAR patients to incident asthma.

Long-term repeatability of induced sputum cells and inflammatory markers in stable, moderately severe COPD

STUDY OBJECTIVES

Neutrophilic inflammation is a major feature of COPD. Induced sputum is increasingly used to monitor inflammatory airway diseases. Although short-term repeatability of selected sputum markers has been extensively studied in several populations, data on the long-term repeatability of induced sputum markers in stable COPD are scant.

DESIGN

Sputum supernatant of 12 patients with stable COPD was analyzed on three separate occasions with 4-weekly intervals. Sputum cells and inflammatory markers interleukin (IL)-8 and soluble intercellular adhesion molecule (sICAM)-1 were measured in supernatant using enzyme-linked immunosorbent assay. Repeatability of sputum markers was expressed by intraclass correlation coefficients (Ri).

MEASUREMENTS AND RESULTS

Sputum induction was safe in all patients. None of the sputum parameters analyzed changed significantly throughout the study. The repeatability for cell differential counts in stable COPD was as follows: total cells, Ri = 0.07; neutrophils, Ri = 0.66; macrophages, Ri = 0.47; eosinophils, Ri = 0.49; and lymphocytes, Ri = 0.58. The repeatability of soluble markers was as follows: IL-8, Ri = 0.50; and sICAM, Ri = 0.58. Sputum neutrophils were negatively correlated with lung function on each separate occasion, whereas soluble markers were not correlated with sputum cells (p > 0.16, all correlations) or lung function (p > 0.24, all correlations).

CONCLUSIONS

Clinically stable, moderate COPD is associated with equally stable sputum inflammatory markers. Repeatability of induced-sputum markers of neutrophilic inflammation in stable COPD is satisfactory, even over extended periods of time. These data support the usefulness of serial monitoring of induced-sputum inflammatory markers in COPD.

Increases in collagen type I synthesis in asthma: the role of eosinophils and transforming growth factor-beta

BACKGROUND

Collagen type I is one of the major deposits in thickening of the reticular basement membrane of asthma.

OBJECTIVE AND METHODS

In this study, we assessed turnover of collagen type I in asthma by measuring procollagen type I C-terminal peptide (PICP) and collagen type I C-terminal telopeptide (ICTP) in induced sputum.

RESULTS

PICP but not ICTP was found to be significantly higher in asthma subjects than in normal volunteers (P < 0.05). In asthma, PICP was inversely correlated with %FEV(1.0) (r = -0.539), and its levels significantly increased upon exacerbation (P < 0.05), indicating that collagen synthesis increases during asthma exacerbation. Additionally, PICP was found to significantly correlate with eosinophil counts in sputum (r = 0.539), indicating that eosinophils stimulate collagen turnover. Because eosinophils can produce TGF-beta, a potent stimulator of collagen synthesis, we immunocytochemically examined TGF-beta-positive cells in sputum. TGF-beta-positive cells significantly correlated with eosinophil counts (r = 0.811) and PICP (r = 0.569), suggesting that TGF-beta released from eosinophils is involved in collagen synthesis.

CONCLUSIONS

The results of the present study suggest that collagen synthesis is stimulated in asthmatic airways by eosinophils through TGF-beta, while collagen degradation is not, and that PICP in sputum can act as a new marker for airway inflammation in asthma.

Preoperative steroid therapy inhibits cytokine production in the lung parenchyma in asthmatic patients

OBJECTIVES

During or after surgery, asthma attacks due to airway hyperresponsiveness (AHR) are likely to occur in patients with bronchial asthma. Preoperative administration of corticosteroid for prevention of perioperative asthma attacks is useful. We examined the mechanism of prevention of perioperative asthma attacks by the preoperative administration of corticosteroid in vitro.

DESIGN

Five patients with asthma were treated with 20 mg of prednisolone orally for 2 preoperative days and 80 mg of methylprednisolone IV immediately before and after surgery. In another five patients without asthma, no steroids were administered. A noncarcinomatous part of the resected tissue from each patient with lung cancer was passively sensitized with the serum of an atopic patient. In the patients without asthma, the tissue was treated with or without dexamethasone, and then mite antigen was added.

MEASUREMENTS

The culture supernatant and lung tissue were recovered, and the supernatant was assayed for histamine, leukotriene E(4) (LTE(4)), interleukin (IL)-5, and tumor necrosis factor (TNF)-alpha. Degranulation of mast cells was measured by tryptase staining of the lung tissue, and the expression of messenger RNA (mRNA) of IL-5 and TNF-alpha was determined by the reverse transcriptase-polymerase chain reaction method.

RESULTS

While preoperative administration of corticosteroid did not suppress the release of histamine and LTE(4) from the lungs of asthmatic patients, it completely suppressed IL-5 and TNF-alpha production at the mRNA level. The same results were obtained in lung tissues of nonasthmatic patients treated in vitro with dexamethasone.

CONCLUSIONS

Our results suggest that corticosteroid treatment reduces AHR and prevents perioperative attacks of asthma primarily by suppressing the production of inflammatory cytokines.

Intrinsic ICAM-1/LFA-1 activation mediates altered responsiveness of atopic asthmatic airway smooth muscle

Cell adhesion molecules (CAMs) have been importantly implicated in the pathobiology of the airway responses in allergic asthma, including inflammatory cell recruitment into the lungs and altered bronchial responsiveness. To elucidate the mechanism of CAM-related mediation of altered airway responsiveness in the atopic asthmatic state, the expressions and actions of intercellular adhesion molecule-1 (ICAM-1) and its counterreceptor ligand lymphocyte function-associated antigen-1 (LFA-1; i.e., CD11a/CD18) were examined in isolated rabbit airway smooth muscle (ASM) tissues and cultured human ASM cells passively sensitized with sera from atopic asthmatic patients or nonatopic nonasthmatic (control) subjects. Relative to control tissues, the atopic asthmatic sensitized ASM exhibited significantly enhanced maximal contractility to acetylcholine and attenuated relaxation responses to isoproterenol. These proasthmatic changes in agonist responsiveness were ablated by pretreating the atopic sensitized tissues with a monoclonal blocking antibody (MAb) to either ICAM-1 or CD11a, whereas a MAb directed against the related beta(2)-integrin Mac-1 had no effect. Moreover, relative to control tissues, atopic asthmatic sensitized ASM cells displayed an autologously upregulated mRNA and cell surface expression of ICAM-1, whereas constitutive expression of CD11a was unaltered. Extended studies further demonstrated that 1) the enhanced expression and release of soluble ICAM-1 by atopic sensitized ASM cells was prevented when cells were pretreated with an interleukin (IL)-5-receptor-alpha blocking antibody and 2) administration of exogenous IL-5 to naive (nonsensitized) ASM cells induced a pronounced soluble ICAM-1 release from the cells. Collectively, these observations provide new evidence demonstrating that activation of the CAM counterreceptor ligands ICAM-1 and LFA-1, both of which are endogenously expressed in ASM cells, elicits autologously upregulated IL-5 release and associated changes in ICAM-1 expression and agonist responsiveness in atopic asthmatic sensitized ASM.