Prostaglandin E (PGE) suppresses macrophage effector mechanisms; however, little is known about the function of PGD in infected alveolar macrophages (AMs). Using serum-opsonized (Ops-) in vitro, we demonstrated that AMs produced PGE and PGD in a time-dependent manner, with PGE levels exceeding those of PGD by 48 h postinfection. Comparison of the effects of both exogenous PGs on AMs revealed that PGD increased phagocytosis and killing through the chemoattractant receptor-homologous molecule expressed on Th2 lymphocytes receptor, whereas PGE had opposite effects, through E prostanoid (EP) receptor 2 (EP2)/EP4-dependent mechanisms. Moreover, PGD inhibited phospholipase C-γ (PLC-γ) phosphorylation, reduced IL-10 production, and increased leukotriene B4 receptor expression. In contrast, exogenous PGE treatment reduced PLC-γ phosphorylation, p38 and nuclear factor κB activation, TNF-α, HO, and leukotriene B, but increased IL-1β production. Using specific compounds to inhibit the synthesis of each PG in vitro and in vivo, we found that endogenous PGD contributed to fungicidal mechanisms and controlled inflammation, whereas endogenous PGE decreased phagocytosis and killing of the fungus and induced inflammation. These findings demonstrate that, although PGD acts as an immunostimulatory mediator to control infection, PGE has immunosuppressive effects, and the balance between these two PGs may limit collateral immune damage at the expense of microbial containment.

Infection with Schistosoma mansoni causes a chronic parasitic disease that progress to severe liver and gastrointestinal damage, and eventually death. During its development into mammalian hosts, immature schistosomula transit through the lung vasculature before they reach the liver to mature into adult worms. A low grade inflammatory reaction is induced during this process. However, molecules that are required for efficient leukocyte accumulation in the lungs of S. mansoni-infected subjects are unknown. In addition, specific leukocyte subsets that mediate pulmonary response during S. mansoni migration through the lung remain to be elucidated. β2 integrins are fundamental regulators of leukocyte trans-endothelial migration and function. Therefore, we investigated their role during experimental schistosomiasis. Mice that express low levels of CD18 (the common β2 integrin subunit) and wild type C57BL/6 mice were subcutaneously infected with S. mansoni cercariae. Cellular profiles of lungs and livers were evaluated in different time points after infection by flow cytometry. Low levels of CD18 affected the accumulation of patrolling Ly6Clow, intermediate Ly6Cinter monocytes, monocyte-derived macrophages and monocyte-derived dendritic cells in the lungs 7 days after infection. This correlated with increased TNF-α levels. Strikingly, low CD18 expression resulted in monocytopenia both in the peripheral blood and bone marrow during acute infection. After 48 days, S. mansoni worm burdens were higher in the hepatic portal system of CD18low mice, which also displayed reduced hepatic accumulation of patrolling Ly6Clow and intermediate Ly6Cinter, but not inflammatory Ly6Chigh monocytes. Higher parasite burden resulted in increased granulomatous lesions in the liver, increased egg deposition and enhanced mortality. Overall, our data point for a fundamental role of CD18 for monocyte hematopoiesis during infection, which promotes an efficient host response against experimental schistosomiasis.

Leukotriene B4 (LTB4) is essential for host immune defence. It increases neutrophil recruitment, phagocytosis and pathogen clearance, and decreases oedema and inflammasome activation. The host response and the role of LTB4 during Achromobacter xylosoxidans infection remain unexplored. Wild-type (129sv) and LTB4 deficient (Alox5 −/−) mice were intratracheally infected with A. xylosoxidans. Wild-type 129sv infected mice survived beyond the 8th day post-infection, exhibited increased levels of LTB4 in the lung on the 1st day, while levels of PGE2 increased on the 7th day post-infection. Infected Alox5 −/− mice showed impaired bacterial clearance, increased lung inflammation, and succumbed to the infection by the 7th day. We found that exogenous LTB4 does not affect the phagocytosis of A. xylosoxidans by alveolar macrophages in vitro. However, treatment of infected animals with LTB4 protected from mortality, by reducing the bacterial load and inflammation via BLT1 signalling, the high affinity receptor for LTB4. Of importance, we uncovered that LTB4 induces gene and protein expression of α-defensin-1 during the infection. This molecule is essential for bacterial clearance and exhibits potent antimicrobial activity by disrupting A. xylosoxidans cell wall. Taken together, our data demonstrate a major role for LTB4 on the control of A. xylosoxidans infection.

No abstract

Erythropoietin (EPO) is a key hormone involved in red blood cell formation, but its effects on nonerythroid cells, such as macrophages, have not been described. Macrophages are key cells in controlling histoplasmosis, a fungal infection caused by Histoplasma capsulatum (Hc). Considering that little is known about EPO's role during fungal infections and its capacity to activate macrophages, in this study we investigated the impact of EPO pretreatment on the alveolar immune response during Hc infection. The consequence of EPO pretreatment on fungal infection was determined by evaluating animal survival, fungal burden, activation of bronchoalveolar macrophages, inflammatory mediator release, and lung inflammation. Pretreatment with EPO diminished mononuclear cell numbers, increased the recruitment of F4/80+/CD80+ and F4/80+/CD86+ cells to the bronchoalveolar space, induced higher production of IFN-γ, IL-6, MIP-1α, MCP-1, and LTB4, reduced PGE2 concentration, and did not affect fungal burden. As a consequence, we observed an increase in lung inflammation with extensive tissue damage that might account for augmented mouse mortality after infection. Our results demonstrate for the first time that EPO treatment has a deleterious impact on lung immune responses during fungal infection.

Histoplasma capsulatum is a dimorphic fungus that develops a yeast-like morphology in host's tissue, responsible for the pulmonary disease histoplasmosis. The recent increase in the incidence of histoplasmosis in immunocompromised patients highlights the need of understanding immunological controls of fungal infections. Here, we describe our discovery of the role of endogenous galectin-1 (Gal-1) in the immune pathophysiology of experimental histoplasmosis. All infected wild-type (WT) mice survived while only 1/3 of Lgals1−/− mice genetically deficient in Gal-1 survived 30 days after infection. Although infected Lgals1−/− mice had increased proinflammatory cytokines, nitric oxide (NO), and elevations in neutrophil pulmonary infiltration, they presented higher fungal load in lungs and spleen. Infected lung and infected macrophages from Lgals1−/− mice exhibited elevated levels of prostaglandin E2 (PGE2, a prostanoid regulator of macrophage activation) and prostaglandin E synthase 2 (Ptgs2) mRNA. Gal-1 did not bind to cell surface of yeast phase of H. capsulatum, in vitro, suggesting that Gal-1 contributed to phagocytes response to infection rather than directly killing the yeast. The data provides the first demonstration of endogenous Gal-1 in the protective immune response against H. capsulatum associated with NO and PGE2 as an important lipid mediator in the pathogenesis of histoplasmosis.

Multiple reaction monitoring (MRM) is one of the most powerful modes of analysis in liquid chromatographic tandem mass spectrometry for quantification of low-concentration metabolites in biological samples. The advances in mass spectrometry enabled the development of high-resolution multiple reaction monitoring (MRM ) and became suitable for the more specific analysis of target analytes. This is important for lipidomic studies and contributes in the medical and pharmaceutical fields, primarily in investigating alterations in cells or fluids relevant to various diseases. Therefore, this work proposes the development of the MRM method for quantification of circulating steroids. We focused on the determination of corticosterone, 11-dehydrocorticosterone (11-DHC), cortisol, cortisone, aldosterone, and progesterone concentration in serum, by using 129sv male mice exposed to chronic unpredictable stress to validate the quantification. The method was conducted according to the ANVISA normative, adopting a coefficient of variation, as well as relative standard deviation and relative error lower than 15% in linearity, intraday and interday precision, and accuracy. For cortisol, corticosterone, and their inert metabolites (cortisone and 11-DHC), the lower limit of quantification was 3.9 ng· mL , while that for progesterone and aldosterone was 7.8 and 15.6 ng· mL , respectively. MRM analysis showed that animals submitted to stressors have 4.5 times more corticosterone in their serum than nonstressed mice. However, 11-DHC concentration does not vary significantly in response to stress for these animals. The results indicate that the method can be applied for quantification of steroids in several biological samples, such as human plasma.

Steroidal hormones profiles can be used to distinguish different biological conditions by the amount of entities present especially in the context of disease. Knowing the levels of such molecules can be crucial to determining a biological response and/or unveil important phenomena. The emergence of high‐resolution methods has amplified the potential of MS and it is currently possible to identify numerous steroid species. In addition, sensitive and very specific modes of acquisition, such as high‐resolution multiple reaction monitoring (MRM), have contributed to this end. In this perspective special feature article, Lúcia Helena Faccioli and colleagues propose a high‐resolution MRM method to quantify steroidal hormones and their metabolites. The results indicate that the method can be applied for quantification of steroids in several biological samples, such as human plasma. Dr. Faccioli is Professor of immunology in the Dept. of Clinical Analyses, Toxicology and Bromatology at the University of Sao Paulo (Brazil). Her main research interests are centered on the study of inflammatory response and role of lipid mediators in several disease including tuberculosis. She also investigates natural products with anti‐inflammatory properties.