Magda F. Serra

Cyclooxygenase-2-Derived Prostaglandin E2 and Lipoxin A4 Accelerate Resolution of Allergic Edema in Angiostrongylus costaricensis-Infected Rats: Relationship with Concurrent Eosinophilia

In noninfected rats, challenge with allergen following local IgE sensitization induced a pleurisy marked by intense protein exudation that plateaued from 30 min to 4 h after challenge, reducing thereafter. Infection of rats with Angiostrongylus costaricensis induced a 5-fold increase in blood eosinophil numbers by 25 days postinfection, whereas the numbers of eosinophils in the pleural cavity ranged from normal to a weak increase. In infected rats, identically sensitized, challenge with Ag induced a much shorter duration of pleural edema with complete resolution by 4 h, but no change in the early edema response. In parallel, infection increased the number of eosinophils recovered from the pleural cavity at 4 h, but not at 30 min, following allergen challenge. Pretreatment with IL-5 (100 IU/kg, i.v.) also increased eosinophil numbers in blood and, after allergen challenge, shortened the duration of the pleural edema and increased pleural eosinophil numbers. There were increases in the levels of both PGE2 and lipoxin A4 (LXA4) in pleural exudate. Selective cyclooxygenase (COX)-2 inhibitors, NS-398, meloxicam, and SC-236, did not alter pleural eosinophilia, but reversed the curtailment of the edema in either infected or IL-5-pretreated rats. Pretreatment of noninfected animals with the PGE analogue, misoprostol, or two stable LXA4 analogues did not alter the magnitude of pleural exudation response, but clearly shortened its duration. These results indicate that the early resolution of allergic pleural edema observed during A. costaricensis infection coincided with a selective local eosinophilia and seemed to be mediated by COX-2-derived PGE2 and LXA4.

Alloxan Diabetes Reduces Pleural Mast Cell Numbers and the Subsequent Eosinophil Influx Induced by Allergen in Sensitized Rats

Alloxan damages insulin-producing cells and has been used as an inducer of experimental diabetes in several animal species. In this study, administration of alloxan (40 mg/kg, i.v.) to rats was followed by a selective and time-dependent reduction in the number of pleural mast cells (50 +/- 2.2%, p < 0.01; mean +/- SEM), while mononuclear cell and eosinophil counts were not altered. As compared to naive rats, the reduction in mast cell numbers was first noted 48 h following alloxan administration and remained unaltered for at least 60 days. It is noteworthy, that the depletion in the mast cell population was not accompanied by alterations in the total amount of histamine stored per cell. Sensitized rats turned diabetic by alloxan treatment performed 72 h before challenge showed a less pronounced antigen-induced mast cell degranulation compared to nondiabetic rats. Moreover, rats injected with alloxan 72 and 48 but not 24 h before challenge, reacted to allergenic challenge with 50% reduction in the number of eosinophils recruited to the pleural cavity within 24 h. We found that the less pronounced eosinophil accumulation did not relate to an intrinsic cell locomotor abnormality since eosinophils from diabetic rats presented similar chemotactic responses to LTB4 and PAF in vitro as compared to matching controls. Insulin (3 IU/rat) restored basal levels of mast cells and reversed the subsequent inhibition of allergen-induced pleural eosinophilia, suggesting a causative relationship between these phenomena. Treatment with insulin also significantly increased the number of mast cells in the pleural cavity of naive rats (from 637 +/- 57 to 978 +/- 79 x 10(3) cells/cavity, p < 0.001). Consistently, previous depletion of mast cells by means of local treatment with compound 48/80 significantly reduced the antigen-induced eosinophil recruitment in sensitized animals. We conclude that the reduction in the pleural mast cell population noted in alloxan-treated rats could be directly implicated in the diminished pleural eosinophil influx following allergen challenge. This hyporesponsiveness is independent of an intrinsic abnormality of cell chemotaxis, but can be imitated by local mast cell depletion.

Nebulized lidocaine prevents airway inflammation, peribronchial fibrosis, and mucus production in a murine model of asthma.

Background: Evidence suggests that nebulized lidocaine is beneficial in asthma therapy, but to what extent and the mechanisms underlying this effect remain poorly understood. The aim of this study was to assess the impact of lidocaine treatment using a murine model of allergic asthma characterized by expression of pivotal features of the disease: inflammation, mucus production, and lung remodeling. Methods: A/J mice sensitized with ovalbumin were treated with inhaled lidocaine or vehicle immediately after ovalbumin intranasal challenges. Lung function, total and differential leukocytes in bronchoalveolar lavage fluid, peribronchial eosinophil density, interleukin (IL)-4, IL-5 and eotaxin-1 levels, epithelial mucus, collagen, extracellular-matrix deposition, matrix metalloproteinase-9 activity, and GATA-3 expression were evaluated. Between five and eight animals per group were used. Results: Inhaled lidocaine inhibited ovalbumin-induced airway hyperreactivity to methacholine, and accumulation of lymphocytes, neutrophils, and eosinophils in bronchoalveolar lavage fluid 24 h after the last allergen provocation. Lidocaine administration also prevented other pathophysiological changes triggered by ovalbumin in lung tissue, including peribronchial eosinophil and neutrophil infiltration, subepithelial fibrosis, increased content of collagen and mucus, matrix metalloproteinase-9 activity, and increased levels of IL-4, IL-5, IL-13, and eotaxin-1. Furthermore, inhaled lidocaine inhibited lung tissue GATA-3 expression in ovalbumin-challenged mice. We also demonstrated that lidocaine inhibited the expression of GATA-3 in ovalbumin-stimulated T cells in vitro. Conclusions: Inhaled lidocaine prevents eosinophilic inflammation, overproduction of mucus, and peribronchial fibrosis in a murine model of asthma, and impaired airway hyperreactivity, possibly by inhibiting allergen-evoked GATA-3 expression and the subsequent up-regulation of proinflammatory cytokines and chemokines.

Modulation of eotaxin formation and eosinophil migration by selective inhibitors of phosphodiesterase type 4 isoenzyme.

This study was undertaken to investigate the possible contribution of the blockade of eotaxin generation to the anti‐eosinophilotactic effect of phosphodiesterase (PDE) type 4 inhibitors. In some experiments, the putative synergistic interaction between PDE type 4 inhibitors and the β2‐agonist salbutamol was also assessed. Sensitized guinea‐pigs aerosolized with antigen (5% ovalbumin, OVA) responded with a significant increase in eotaxin and eosinophil levels in the bronchoalveolar lavage fluid (BALF) at 6 h. Eosinophil recruitment was inhibited by both PDE type 4 inhibitors rolipram (5 mg kg−1, i.p.) and RP 73401 (5 mg kg−1, i.p.) treatments. In contrast, only rolipram inhibited eotaxin production. Sensitized rats intrapleurally challenged (i.pl.) with antigen (OVA, 12 μg cavity−1) showed a marked eosinophil infiltration at 24 h, preceded by eotaxin generation at 6 h. Intravenous administration of a rabbit anti‐mouse eotaxin antibody (0.5 mg kg−1) significantly reduced allergen‐evoked eosinophilia in this model. Local pretreatment with rolipram (40 μg cavity−1) or RP 73401 (40 μg cavity−1) 1 h before challenge reduced eosinophil accumulation evaluated in the rat pleural effluent, but only the former was active against eotaxin generation. The inhibitors of PDE type 3 (SK&F 94836) and type 5 (zaprinast) failed to alter allergen‐evoked eosinophil recruitment in rats. Local injection of β2‐agonist salbutamol (20 μg cavity−1) inhibited both eosinophil accumulation and eotaxin production following pleurisy. The former was better inhibited when salbutamol and rolipram were administered in combination. Treatment with rolipram and RP 73401 dose‐dependently inhibited eosinophil adhesion and migration in vitro. These effects were clearly potentiated by salbutamol at concentrations that had no effect alone. Our findings indicate that although rolipram and RP 73401 are equally effective in inhibiting allergen‐induced eosinophil infiltration only the former prevents eotaxin formation, indicating that PDE 4 inhibitors impair eosinophil accumulation by mechanisms independent of eotaxin production blockade.

Lidocaine-derivative JMF2-1 prevents ovalbumin-induced airway inflammation by regulating the function and survival of T cells

Cite this as: P. C. Olsen, T. P. T. Ferreira, M. F. Serra, F. A. Farias‐Filho, B. P. Fonseca, J. P. B. Viola, R. S. B. Cordeiro, P. M. R. Silva, J. C. S. Costa and M. A. Martins, Clinical & Experimental Allergy, 2011 (41) 250–259.

Histamine modulates mast cell degranulation through an indirect mechanism in a model IgE‐mediated reaction

Histamine is released in inflammatory reactions and exerts an immunoregulatory function on cells present in the microenvironment. In this study, we compared the effect of histamine on degranulation of mast cells derived from animals bearing a parasitic infection with those from uninfected animals. Peritoneal mast cells (PMC) were obtained 24 days after infection of Wistar rats with Toxocara canis. The degree of degranulation was assessed either morphologically or by measuring the release of β‐hexosaminidase and TNF‐α. Non‐purified PMC or mast cells immunomagnetically purified with mAb AA4 were used. An increase in degranulation of non‐purified mast cells from infected animals was observed after incubation with histamine in vitro or when histamine was injected into the peritoneal cavity. When a purified mast cell population was used, this effect was no longer observed. Supernatants from spleen cells stimulated with histamine induced degranulation of purified mast cells, and again, this was potentiated with PMC from infected animals. However, when supernatants from peritoneal macrophages similarly stimulated were used, a reduction in the degranulation of PMC from infected animals was observed. Our results suggest that histamine may act as a regulator of mast cell degranulation, thus modulating inflammatory responses due to infection with certain parasites.

Antigen-induced pleural eosinophilia is suppressed in diabetic rats: role of corticosteroid hormones

Previous studies have evidenced for the existence of interactive regulatory mechanisms between insulin and steroid hormones in different systems. In this study, we have investigated whether endogenous corticosteroids could be implicated in the hyporeactivity to antigen challenge observed in sensitized diabetic rats. Alloxinated rats showed a long-lasting increase in the blood glucose levels and a reduction in the number of pleural mast cells at 48 and 72 hr, but not at 24 hr after alloxan administration. In parallel, they also showed a significant elevation in the plasma levels of corticosterone together with an increase in the adrenal/body weight ratio. Antigen-evoked eosinophil accumulation appeared significantly reduced in rats pretreated with dexamethasone as well as in those rendered diabetic 72 hr after alloxan. In the same way, naive animals treated with dexamethasone also responded with a significant decrease in the number of pleural mast cells. Interestingly, when sensitized diabetic rats were pretreated with the steroid antagonist RU 38486 a reversion of the reduction in the allergen-induced eosinophil accumulation was noted. We conclude that the down-regulation of the allergic inflammatory response in diabetic rats is close-related to reduction in mast cell numbers and over expression of endogenous corticosteroids.

Systemic anaphylaxis is prevented in alloxan-diabetic rats by a mechanism dependent on glucocorticoids

This study was undertaken to examine whether glucocorticoids could be implicated in the hyporesponsiveness of diabetic rats to systemic anaphylaxis. Rats were actively sensitized with a mixture of Al(OH)(3) plus ovalbumin and challenged i.v. with ovalbumin 14 days later. Diabetes was induced by alloxan-injected i.v. either before or after sensitization. Elevation of total and specific serum immunoglobulin E (IgE) was abolished in rats turned diabetic and then sensitised, but not in those first sensitised and then turned diabetic. In both conditions, increased serum corticosterone levels occurred in parallel with protection of diabetic animals against fatal shock, intestinal haemorrhage and elevation in plasma histamine levels evoked by antigen challenge. The resistance of diabetic rats to fatal shock was no longer significantly different from that of non-diabetic rats following treatment with the glucocorticoid receptor antagonist RU 486 (mifepristone). These findings indicate that endogenous glucocorticoid plays a pivotal role in the phenomenon of hyporeactivity to systemic anaphylaxis in alloxan-diabetic rats.

JM25-1, a Lidocaine Analog Combining Airway Relaxant and Antiinflammatory Properties: Implications for New Bronchospasm Therapy.

Background:Inhaled lidocaine antagonized bronchospasm in animal models and patients, but adverse effects limited its efficacy. This study evaluated the antibronchospasm potential of the analog JM25-1, exploring in vitro mechanisms and translation to an animal model. Methods:The effectiveness of JM25-1 was assessed in GH3 cells, rat tracheal rings, mouse lymphocytes, and human eosinophil systems in vitro, assessing changes in Na+ current, contraction, proliferation, and survival, respectively. Lung function and inflammatory changes were studied in ovalbumin-sensitized mice. Results:The efficacy of JM25-1 was higher than lidocaine in inhibiting carbachol-induced and calcium-induced tracheal contractions (maximum effect inhibition at 1 mM [%]: 67 ± 10 [JM25-1] vs. 41 ± 11 [lidocaine] [P < 0.001] for carbachol; 100 ± 3 [JM25-1] vs. 36 ± 26 [lidocaine] [P < 0.001] for Ca2+; mean ± SD; n = 9 each) but lower in Na+ current (50% inhibitory concentration = 151.5, n = 8 vs. 0.2 mM; n = 5; P < 0.001). JM25-1 also inhibited eosinophil survival (dead cells [%]: 65 ± 6; n = 4; P < 0.001 at 1 mM) and lymphocyte proliferation (cells in phase S + G2 [%]: 94 ± 10; n = 6; P < 0.001) at 0.6 mM. Aerosolized JM25-1 (1%) decreased lung eosinophil numbers from 13.2 ± 2.4 to 1.7 ± 0.7 × 104/&mgr;m2 (n = 6; P < 0.001) and neutrophils from 1.9 ± 0.4 to 0.2 ± 0.1 × 104/&mgr;m2 (n = 7; P < 0.001). Other parameters, including airway hyperreactivity, cytokines, mucus, and extracellular matrix deposition, were also sensitive to aerosolized JM25-1. Conclusion:These findings highlight the potential of JM25-1, emphasizing its putative value in drug development for clinical conditions where there is bronchospasm.

Local anaesthetic medication for the treatment of asthma

It is presumed that drugs able to prevent bronchial spasm and/or inflammation may have therapeutic potential to control asthma symptoms. The local anaesthetic lidocaine has recently received increased attention as an alternative form of treatment for asthmatic patients. This paper reviews the major findings on the topic and summarizes the putative mechanisms underlying the airway effects of local anaesthetic agents. We think that lidocaine extends the spectrum of options in asthma therapy, probably by counteracting both spasmogenic and inflammatory stimuli in the bronchial airways. The possibility of development of new anti-asthma compounds based on the synthesis of lidocaine derivatives is also on the horizon.