Wothan Tavares-de-Lima

Role of sex hormones in allergic inflammation in mice

Background A number of clinical studies have documented both a pro‐ and anti‐inflammatory role for sex hormones in the context of lung inflammation and worsening of asthma.

Formaldehyde induces lung inflammation by an oxidant and antioxidant enzymes mediated mechanism in the lung tissue

Formaldehyde (FA) is an indoor and outdoor pollutant widely used by many industries, and its exposure is associated with inflammation and oxidative stress in the airways. Our previous studies have demonstrated the role of reactive oxygen species (ROS) in lung inflammation induced by FA inhalation but did not identify source of the ROS. In the present study, we investigate the effects of FA on the activities and gene expression of glutathione peroxidase (GPX), glutathione reductase (GR), glutathione S-transferase (GST), superoxide dismutase (SOD) 1 and 2, catalase (CAT), nitric oxide synthase (iNOS and cNOS) and cyclooxygenase (COX) 1 and 2. The hypothesized link between NADPH-oxidase, nitric oxide synthase and cyclooxygenase, the lung inflammation after FA inhalation was also investigated. For experiments, male Wistar rats were submitted to FA inhalation (1%, 90 min daily) for 3 consecutive days. The treatments with apocynin and indomethacin before the FA exposure reduced the number of neutrophils recruited into the lung. Moreover, the treatments with apocynin and indomethacin blunted the effect of FA on the generation of IL-1β, while the treatments with L-NAME and apocynin reduced the generation of IL-6 by lung explants when compared to the untreated group. FA inhalation increased the levels of NO and hydrogen peroxide by BAL cells cultured and the treatments with apocynin and l-NAME reduced these generations. FA inhalation did not modify the activities of GPX, GR, GST and CAT but reduced the activity of SOD when compared to the naïve group. Significant increases in SOD-1 and -2, CAT, iNOS, cNOS and COX-1 expression were observed in the FA group compared to the naïve group. The treatments with apocynin, indomethacin and L-NAME reduced the gene expression of antioxidant and oxidant enzymes. In conclusion, our results indicate that FA causes a disruption of the physiological balance between oxidant and antioxidant enzymes in lung tissue, most likely favoring the oxidant pathways and thus positively modulating lung inflammation.

Reduced allergic lung inflammation in rats following formaldehyde exposure: Long-term effects on multiple effector systems

Clinical and experimental evidences show that formaldehyde (FA) exposure has an irritant effect on the upper airways. As being an indoor and outdoor pollutant, FA is known to be a causal factor of occupational asthma. This study aimed to investigate the repercussion of FA exposure on the course of a lung allergic process triggered by an antigen unrelated to FA. For this purpose, male Wistar rats were subjected to FA inhalation for 3 consecutive days (1%, 90-min daily), subsequently sensitized with ovalbumin (OVA)-alum via the intraperitoneal route, and 2 weeks later challenged with aerosolized OVA. The OVA challenge in rats after FA inhalation (FA/OVA group) evoked a low-intensity lung inflammation as indicated by the reduced enumerated number of inflammatory cells in bronchoalveolar lavage as compared to FA-untreated allergic rats (OVA/OVA group). Treatment with FA also reduced the number of bone marrow cells and blood leukocytes in sensitized animals challenged with OVA, which suggests that the effects of FA had not been only localized to the airways. As indicated by passive cutaneous anaphylactic reaction, FA treatment did not impair the anti-OVA IgE synthesis, but reduced the magnitude of OVA challenge-induced mast cell degranulation. Moreover, FA treatment was associated to a diminished lung expression of PECAM-1 (platelet-endothelial cell adhesion molecule 1) in lung endothelial cells after OVA challenge and an exacerbated release of nitrites by BAL-cultured cells. Keeping in mind that rats subjected solely to either FA or OVA challenge were able to significantly increase the cell influx into lung, our study shows that FA inhalation triggers long-lasting effects that affect multiple mediator systems associated to OVA-induced allergic lung such as the reduction of mast cells activation, PECAM-1 expression and exacerbation of NO generation, thereby contributing to the decrease of cell recruitment after the OVA challenge. In conclusion, repeated expositions to air-borne FA may impair the lung cell recruitment after an allergic stimulus, thereby leading to a non-responsive condition against inflammatory stimuli likely those where mast cells are involved.

Protective effect of estradiol on acute lung inflammation induced by an intestinal ischemic insult is dependent on nitric oxide.

ABSTRACT Introduction: It has been shown that the innate immune system mediates acute lung inflammation triggered by intestinal trauma. Sexual dimorphism modulates the profile of TH1 and TH2 lymphocytes, and accordingly sex hormones may modulate acute lung inflammation by intestinal ischemia/reperfusion (I/R). Studies indicate that female rats are relatively resistant to organ injury caused by hemorrhagic shock and that the gut of female is more resistant than that of the male to deleterious effects of ischemic injury. At the present study, we investigated the effect of estradiol (E2) on the lung inflammation after intestinal I/R and its interaction with the nitric oxide (NO) pathway. Methods: Anesthetized female rats submitted or not to 7 days ovariectomy (OVx) were subjected to occlusion of the superior mesenteric artery during 45 min, followed by 2 h of reperfusion. Groups of rats were treated with E2 (17&bgr;-estradiol, 280 &mgr;g/kg, s.c.) 24 h before ischemia and/or with the nonselective NO synthase inhibitor L-NAME (N&ohgr;-nitro-L-arginine methyl ester hydrochloride) (5 mg/kg, i.v.). In a parallel set of experiments, the selective NO synthase inhibitor, aminoguanidine (50 mg/kg i.v.), was given 1 h before ischemia. In all groups, lung vascular permeability (LVP) was assessed using the Evans blue dye extravasation method, neutrophil recruitment to the tissues by the standard myeloperoxidase (MPO) method, and endothelial NO synthase (eNOS) protein expression by Western blot. Results: In OVx rats, LVP and MPO were increased after intestinal I/R as compared with intact controls. Estradiol reverted the LVP, but not MPO. Aminoguanidine reduced LVP in OVx rats. The E2 protective effect on LVP was abolished by L-NAME; moreover, an increase in LVP even when compared with OVx rats treated only with L-NAME was observed. In addition, lung eNOS protein expression was reduced in OVx-I/R rats in comparison to intact controls and the E2 inhibited this effect. Conclusions: Estradiol treatment is able to reduce lung inflammation due to intestinal I/R, but with the concomitant blockade of NOS activity, this effect is abolished. Nitric oxide probably reduces the vascular deleterious effects of intestinal I/R, and E2 pretreatment reduces lung inflammation after intestinal I/R and exerts these effects by modulating eNOS protein expression in the lungs.

Interference of methysergide, a specific 5‐hydroxytryptamine receptor antagonist, with airway chronic allergic inflammation and remodelling in a murine model of asthma

Background Airway remodelling encompasses the structural changes observed in asthmatic airways. Mast cells, through the release of histamine and 5‐hydroxytryptamine (serotonin), are implicated in early asthmatic reactions, bronchoconstriction and mucosal oedema, and in the development of bronchial hyperresponsiveness. However, the association between serotonin and remodelling processes in murine model of airways inflammation remains to be elucidated.

Modulation of the Induction of Lung and Airway Allergy in the Offspring of IFN-γ-Treated Mother Mice

Recent studies have highlighted the influence of fetal/maternal interactions on the development of asthma. Because IFN-γ reduces Th2-mediated allergic responses, we assessed its capacity to modulate asthma in the offspring when injected into mothers during pregnancy. IFN-γ was injected in CD1 female mice on day 6.5 of gestation. Immediately after birth, male newborns were housed in cages with interchanged mothers: the offspring from IFN-γ-treated mothers were breastfed by normal mothers (IFN/nor), and those from normal mothers were breastfed by IFN-γ-treated (Nor/IFN) or normal mothers (Nor/nor). Immediately after weaning, the spleen cells from IFN/nor and Nor/IFN mice produced less IL-4 and more IFN-γ than Nor/nor mice when stimulated with Con A. At the age of 6–7 wk, mice were immunized with OVA on days 0 and 7. From day 14 to 16, they were exposed to aerosolized OVA. The bronchoalveolar lavage fluid from Nor/nor mice showed eosinophilia, a large number of these cells being present in perivascular and peribronchial regions of lung tissues. IFN/nor or Nor/IFN mice showed greatly reduced eosinophil numbers in bronchoalveolar lavage fluid. In addition, lung sections from IFN/nor, but not Nor/IFN mice showed almost normal histology. In OVA-sensitized IFN/nor and Nor/IFN mice, the production of IFN-γ, IL-4, and IL-5 by spleen cells was significantly reduced as compared with cells from the OVA-sensitized Nor/nor group. IgE and anaphylactic IgG1 were also reduced in plasma of IFN/nor mice. In conclusion, the presence of IFN-γ during pregnancy confers to the fetus a protection against allergenic provocations in the adult life.

Exposure to low doses of formaldehyde during pregnancy suppresses the development of allergic lung inflammation in offspring.

Formaldehyde (FA) is an environmental and occupational pollutant, and its toxic effects on the immune system have been shown. Nevertheless, no data are available regarding the programming mechanisms after FA exposure and its repercussions for the immune systems of offspring. In this study, our objective was to investigate the effects of low-dose exposure of FA on pregnant rats and its repercussion for the development of allergic lung inflammation in offspring. Pregnant Wistar rats were assigned in 3 groups: P (rats exposed to FA (0.75 ppm, 1 h/day, 5 days/week, for 21 days)), C (rats exposed to vehicle of FA (distillated water)) and B (rats non-manipulated). After 30 days of age, the offspring was sensitised with ovalbumin (OVA)-alum and challenged with aerosolized OVA (1%, 15 min, 3 days). After 24 h the OVA challenge the parameters were evaluated. Our data showed that low-dose exposure to FA during pregnancy induced low birth weight and suppressed the development of allergic lung inflammation and tracheal hyperresponsiveness in offspring by mechanisms mediated by reduced anaphylactic antibodies synthesis, IL-6 and TNF-alpha secretion. Elevated levels of IL-10 were found. Any systemic alteration was detected in the exposed pregnant rats, although oxidative stress in the uterine environment was evident at the moment of the delivery based on elevated COX-1 expression and reduced cNOS and SOD-2 in the uterus. Therefore, we show the putative programming mechanisms induced by FA on the immune system for the first time and the mechanisms involved may be related to oxidative stress in the foetal microenvironment.

Tumor necrosis factor is not associated with intestinal ischemia/reperfusion-induced lung inflammation.

Intestinal ischemia-reperfusion (I/R) injury may cause acute systemic and lung inflammation. Here, we revisited the role of TNF-&agr; in an intestinal I/R model in mice, showing that this cytokine is not required for the local and remote inflammatory response upon intestinal I/R injury using neutralizing TNF-&agr; antibodies and TNF ligand-deficient mice. We demonstrate increased neutrophil recruitment in the lung as assessed by myeloperoxidase activity and augmented IL-6, granulocyte colony-stimulating factor, and KC levels, whereas TNF-&agr; levels in serum were not increased and only minimally elevated in intestine and lung upon intestinal I/R injury. Importantly, TNF-&agr; antibody neutralization neither diminished neutrophil recruitment nor any of the cytokines and chemokines evaluated. In addition, the inflammatory response was not abrogated in TNF and TNF receptors 1 and 2-deficient mice. However, in view of the damage on the intestinal barrier upon intestinal I/R with systemic bacterial translocation, we asked whether Toll-like receptor (TLR) activation is driving the inflammatory response. In fact, the inflammatory lung response is dramatically reduced in TLR2/4-deficient mice, confirming an important role of TLR receptor signaling causing the inflammatory lung response. In conclusion, endogenous TNF-&agr; is not or minimally elevated and plays no role as a mediator for the inflammatory response upon ischemic tissue injury. By contrast, TLR2/4 signaling induces an orchestrated cytokine/chemokine response leading to local and remote pulmonary inflammation, and therefore disruption of TLR signaling may represent an alternative therapeutic target.

Amphetamine modulates cellular recruitment and airway reactivity in a rat model of allergic lung inflammation.

Asthma is characterized by pulmonary cellular infiltration, vascular exudation and airway hyperresponsiveness. Several drugs that modify central nervous system (CNS) activity can modulate the course of asthma. Amphetamine (AMPH) is a highly abused drug that presents potent stimulating effects on the CNS and has been shown to induce behavioral, biochemical and immunological effects. The purpose of this study was to investigate the effects of AMPH on pulmonary cellular influx, vascular permeability and airway reactivity. AMPH effects on adhesion molecule expression, IL-10 and IL-4 release and mast cell degranulation were also studied. Male Wistar rats were sensitized with ovalbumin (OVA) plus alum via subcutaneous injection. One week later, the rats received another injection of OVA-alum (booster). Two weeks after this booster, the rats were subjected to AMPH treatment 12 h prior to the OVA airway challenge. In rats treated with AMPH, the OVA challenge reduced cell recruitment into the lung, the vascular permeability and the cellular expression of ICAM-1 and Mac-1. Additionally, elevated levels of IL-10 and IL-4 were found in samples of lung explants from allergic rats. AMPH treatment, in comparison, increased IL-10 levels but reduced those of IL-4 in the lung explants. Moreover, the tracheal responsiveness to methacholine (MCh), as well as to an in vitro OVA challenge, was reduced by AMPH treatment, and levels of PCA titers were not modified by the drug. Our findings suggest that single AMPH treatment down-regulates several parameters of lung inflammation, such as cellular migration, vascular permeability and tracheal responsiveness. These results also indicate that AMPH actions on allergic lung inflammation include endothelium-leukocyte interaction mechanisms, cytokine release and mast cell degranulation.

Female sex hormones mediate the allergic lung reaction by regulating the release of inflammatory mediators and the expression of lung E-selectin in rats

BackgroundFluctuations of estradiol and progesterone levels caused by the menstrual cycle worsen asthma symptoms. Conflicting data are reported in literature regarding pro and anti-inflammatory properties of estradiol and progesterone.MethodsFemale Wistar rats were ovalbumin (OVA) sensitized 1 day after resection of the ovaries (OVx). Control group consisted of sensitized-rats with intact ovaries (Sham-OVx). Allergic challenge was performed by aerosol (OVA 1%, 15 min) two weeks later. Twenty four hours after challenge, BAL, bone marrow and total blood cells were counted. Lung tissues were used as explants, for expontaneous cytokine secretion in vitro or for immunostaining of E-selectin.ResultsWe observed an exacerbated cell recruitment into the lungs of OVx rats, reduced blood leukocytes counting and increased the number of bone marrow cells. Estradiol-treated OVx allergic rats reduced, and those treated with progesterone increased, respectively, the number of cells in the BAL and bone marrow. Lungs of OVx allergic rats significantly increased the E-selectin expression, an effect prevented by estradiol but not by progesterone treatment. Systemically, estradiol treatment increased the number of peripheral blood leukocytes in OVx allergic rats when compared to non treated-OVx allergic rats. Cultured-BAL cells of OVx allergic rats released elevated amounts of LTB4 and nitrites while bone marrow cells increased the release of TNF-α and nitrites. Estradiol treatment of OVx allergic rats was associated with a decreased release of TNF-α, IL-10, LTB4 and nitrites by bone marrow cells incubates. In contrast, estradiol caused an increase in IL-10 and NO release by cultured-BAL cells. Progesterone significantly increased TNF- α by cultured BAL cells and bone marrow cells.ConclusionsData presented here suggest that upon hormonal oscillations the immune sensitization might trigger an allergic lung inflammation whose phenotype is under control of estradiol. Our data could contribute to the understanding of the protective role of estradiol in some cases of asthma symptoms in fertile ans post-menopausal women clinically observed.