Objective: One third of asthmatic women report a decreased expiratory peak flow during menses. Since asthma is characterized by lung inflammation and bronchopulmonary hyperresponsiveness, we investigated the role played by estradiol in allergic lung inflammation. Methods: Cell migration to the lungs of allergic female rats subjected to oophorectomy (OVx) was compared to that in their sham-operated (sham) control counterparts. Seven days after OVx or sham operation, the rats were sensitized intraperitoneally with ovalbumin (OA, 1 mg/kg) suspended in aluminum hydroxide (day 0). At day 7, a subcutaneous booster of OA was performed and an aerosolized OA challenge was carried out at day 14. One day later (day 15), the rats were killed and cell counts were performed in bronchoalveolar lavages (BAL), in peripheral blood and in bone marrow lavages. Results: After the antigen challenge, OVx rats showed a significant decrease in cell migration to the lung as compared to sham-operated rats. Differential analyses of BAL revealed a reduced number of eosinophils, mononuclear cells and neutrophils. In contrast, in bone marrow as well as in the peripheral blood the numbers of eosinophils, mononuclear cells and neutrophils were increased relative to sham controls. Mast cell numbers were similar in both groups. The estradiol receptor antagonist tamoxifen decreased the allergic lung inflammation in intact rats down to levels similar to those found in untreated OVx rats. In contrast, 17β-estradiol replacement in OVx rats reestablished the allergic lung inflammation, as observed by an elevated number of eosinophils, mononuclear cells and neutrophils recovered in BAL. Similarly, an elevated number of inflammatory cells were quantified in BAL from allergic OVx rats when corticosterone effects were blocked with metyrapone or RU-486. Conclusion: Our results suggest that estradiol has proinflammatory actions on the allergic lung response, and these actions seem to be mediated, at least in part, by endogenous glucocorticoids.

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We investigated in rats the influence of the lymphatic system and of tumor necrosis factor (TNF) on the lung inflammation resulting from intestinal ischemia/reperfusion (I/R) performed by 45-min occlusion of the superior mesenteric artery followed by 2 h of reperfusion. A group of rats had the thoracic lymph duct ligated before I/R. In lungs, intestinal I/R evoked a significant neutrophil recruitment, and enhanced microvascular permeability, in addition to generation of TNF in serum. In the gut, there was lowered lactate dehydrogenase (LDH) activity and increased microvascular permeability. Upon lymph duct ligation, I/R rats had a significant reduction of pulmonary neutrophil recruitment and plasma extravasation, in addition to high amounts of TNF in the lymph, contrasting with undetectable levels in the serum. In addition, LDH gut levels in these animals were close to basal values; there was also some (yet significant) reduction of microvascular permeability, suggesting that the ligation of the lymphatic duct exerted some degree of protection against the intestinal injury caused by I/R. In I/R rats, the treatment with pentoxifylline (PTX) reduced TNF in serum and blunted other lung alterations. The gut alterations caused by intestinal I/R were largely blocked by PTX. On the other hand, in I/R rats with lymph duct ligation, PTX exacerbated the reduction of pulmonary neutrophil recruitment, but did not affect pulmonary and intestinal microvascular permeabilities. Similarly, intestinal LDH activity and serum TNF levels were unaffected. Overall, our data show that the pulmonary and gut injuries induced by intestinal I/R are partially dependent on TNF, which is conceivably generated in the injured gut tissue due to intestinal I/R and carried by the lymphatic system. Thus, the mesenteric lymphatic drainage seems to play a role as a path modulator of the pulmonary and intestinal dysfunctions that follow a gut trauma.

We evaluated the role of estradiol and progesterone in allergic lung inflammation. Rats were ovariectomized (Ovx) and, 7 days later, were sensitized with ovalbumin (OA) and challenged after 2 wk with inhaled OA; experiments were performed 1 day thereafter. Ovx-allergic rats showed reduced cell recruitment into the bronchoalveolar lavage (BAL) fluid relative to sham-Ovx allergic rats, as was observed in intact allergic rats treated with ICI-182,780. Estradiol increased the number of cells in the BAL of Ovx-allergic rats, whereas progesterone induced an additional reduction. Cells of BAL and bone marrow (BM) of Ovx-allergic rats released elevated amounts of IL-10 and reduced IL-1beta and TNF-alpha. BM cells of Ovx-allergic rats released increased amounts of IL-10 and lower amounts of IL-4. Estradiol treatment of Ovx-allergic rats decreased the release of IL-10 but increased that of IL-4 by BM cells. Estradiol also caused an increased release of IL-1beta and TNF-alpha by BAL cells. Progesterone significantly increased the release of IL-10, IL-1beta, and TNF-alpha by BAL cells and augmented that of IL-4 by BM cells. Degranulation of bronchial mast cells from Ovx rats was reduced after in vitro challenge, an effect reverted by estradiol but not by progesterone. We suggest that the serum estradiol-to-progesterone ratio might drive cellular recruitment, modulating the pulmonary allergy and profile of release of anti-inflammatory or inflammatory cytokines. The existence of such dual hormonal effects suggests that the hormone therapy of asthmatic postmenopausal women and of those suffering of premenstrual asthma should take into account the possibility of worsening the pulmonary conditions.