Mechanisms of leukocyte NADPH oxidase regulation remain actively investigated. We showed previously that vascular and macrophage oxidase complexes are regulated by the associated redox chaperone PDI. Here, we investigated the occurrence and possible underlying mechanisms of PDI-mediated regulation of neutrophil NADPH oxidase. In a semirecombinant cell-free system, PDI inhibitors scrRNase (100 μg/mL) or bacitracin (1 mM) near totally suppressed superoxide generation. Exogenously incubated, oxidized PDI increased (by ∼40%), whereas PDIred diminished (by ∼60%) superoxide generation. No change occurred after incubation with PDI serine-mutated in all four redox cysteines. Moreover, a mimetic CxxC PDI inhibited superoxide production by ∼70%. Thus, oxidized PDI supports, whereas reduced PDI down-regulates, intrinsic membrane NADPH oxidase complex activity. In whole neutrophils, immunoprecipitation and colocalization experiments demonstrated PDI association with membrane complex subunits and prominent thiol-mediated interaction with p47phox in the cytosol fraction. Upon PMA stimulation, PDI was mobilized from azurophilic granules to cytosol but did not further accumulate in membranes, contrarily to p47phox. PDI-p47phox association in cytosol increased concomitantly to opposite redox switches of both proteins; there was marked reductive shift of cytosol PDI and maintainance of predominantly oxidized PDI in the membrane. Pulldown assays further indicated predominant association between PDIred and p47phox in cytosol. Incubation of purified PDI (>80% reduced) and p47phox in vitro promoted their arachidonate-dependent association. Such PDI behavior is consistent with a novel cytosolic regulatory loop for oxidase complex (re)cycling. Altogether, PDI seems to exhibit a supportive effect on NADPH oxidase activity by acting as a redox-dependent enzyme complex organizer.

Glycosphingolipids (GSLs) are ubiquitous membrane components and have key roles in biological systems, acting as second messengers or modulators of signal transduction by affecting several events, ranging from cell adhesion, cell growth, cell motility, regulation of apoptosis and cell cycle. Over the last 20 years our laboratory and other research groups determined the glycan and ceramide structures of more than 20 GSLs from several pathogenic/opportunistic fungi, using a combination of gas chromatography, mass spectrometry, nuclear magnetic resonance as well as other immunochemical and biochemical techniques. Fungal GSLs can be divided in two major classes: neutral GSLs, galactosyl- and glucosylceramide (GlcCer), and acidic GSLs, the glycosylinositol-phosphorylceramides (GIPCs). Glycosyl structures in fungal GIPCs exhibited significant structural diversity and distinct composition when compared to mammalian GSLs, e.g., the expression of inositol-mannose and inositol-glucosamine cores and the terminal residue of β-D-galactofuranose which are absent in mammalian cells. Studies performed by our group demonstrated that GIPC (Galfβ6[Manα3]Manα2InsPCer) elicited in patients with paracoccidioidomycosis an immune response with production of antibodies directed to the terminal residue of β-D-galactofuranose. Further studies also showed that inhibition of GlcCer biosynthetic pathways affects fungal colony formation, spore germination and hyphal growth, indicating that enzymes involved in GlcCer biosynthesis may represent promising targets for the therapy of fungal infections. Recently, it was shown that GlcCer and GIPCs are preferentially localized in membrane microdomains and monoclonal antibodies directed to these GSLs interfere in several fungal biological processes such as growth and morphological transition. This review focuses on glycan structures carried on sphingolipids of pathogenic/opportunistic fungi, and aspects of their biological significance are discussed.

Acidic glycosphingolipid components were extracted from the opportunistic mycopathogen Aspergillus fumigatus and identified as inositol phosphorylceramide and glycosylinositol phosphorylceramides (GIPCs). Using nuclear magnetic resonance sppectroscopy, mass spectrometry, and other techniques, the structures of six major components were elucidated as Ins-P-Cer (Af-0), Manp(α1→3)Manp(α1→2)Ins-P-Cer (Af-2), Manp(α1→2)Manp(α1→3)Manp(α1→2)Ins-P-Cer (Af-3a), Manp(α1→3)[Galf(β1→6)]Manp(α1→2)-Ins-P-Cer (Af-3b), Manp(α1→2)-Manp(α1→3)[Galf(β1→6)]Manp(α1→2)Ins-P-Cer (Af-4), and Manp(α1→3)Manp(α1→6)GlcpN(α1→2)Ins-P-Cer (Af-3c) (where Ins = myo-inositol and P = phosphodiester). A minor A. fumigatus GIPC was also identified as the N-acetylated version of Af-3c (Af-3c*), which suggests that formation of the GlcNα1→2Ins linkage may proceed by a two-step process, similar to the GlcNα1→6Ins linkage in glycosylphosphatidylinositol (GPI) anchors (transfer of GlcNAc, followed by enzymatic de-N-acetylation). The glycosylinositol of Af-3b, which bears a distinctive branching Galf(β1→6) residue, is identical to that of a GIPC isolated previously from the dimorphic mycopathogen Paracoccidioides brasiliensis (designated Pb-3), but components Af-3a and Af-4 have novel structures. Overlay immunostaining of A. fumigatus GIPCs separated on thin-layer chromatograms was used to assess their reactivity against sera from a patient with aspergillosis and against a murine monoclonal antibody (MEST-1) shown previously to react with the Galf(β1→6) residue in Pb-3. These results are discussed in relation to pathogenicity and potential approaches to the immunodiagnosis of A. fumigatus.

Gastric ulcers are a significant medical problem and the development of complications lead to significant mortality rates worldwide. In Brazil, Carthamus tinctorius L., Asteraceae, seeds essential oil, the safflower oil, is currently used as a thermogenic compound and as treatment for problems related to the cardiovascular system. In this study, by Raman spec- troscopy, it was shown that oleic and linoleic acids are the compounds present in higher concentrations in the safflower oil. We demonstrated that safflower oil (750 mg/kg, p.o.) de- crease the ulcerogenic lesions in mice after the administration of hydrochloric acid-ethanol. The gastric ulcers induced by non-steroidal anti-inflammatory drug (NSAID) in mice treated with cholinomimetics were treated with four different doses of safflower oil, of which, the dose of 187.5 mg/kg (p.o.) showed significant antiulcerogenic properties (**p < 0.01). More- over, the safflower oil at doses of 187.5 mg/kg (i.d.) increased the pH levels, gastric volume (**p < 0.01) and gastric mucus production (***p < 0.001), and decreased the total gastric acid secretion (***p < 0.001). The acute toxicity tests showed that safflower oil (5.000 mg/kg, p.o.) had no effect on mortality or any other physiological parameter. Ecotoxicological tests per- formed using Daphnia similis showed an EC50 at 223.17 mg/l, and therefore safflower oil can be considered “non-toxic” based on the directive 93/67/EEC on risk assessment for new noti-fied substances by European legislation. These results indicate that the antiulcer activity of Safflower oil may be due to cytoprotective effects, which serve as support for new scientific studies related to this pathology.

Antiretrovirals (ARVs) have been detected in aquatic ecosystems throughout the world; however, studies focused on assessing their ecotoxicological effects on marine aquatic organisms are still rare. In the present study, the predicted environmental concentration (PEC) of 13 ARVs was estimated for surface seawater from Santos Bay, Brazil, according to the European Medicines Agency (EMEA) guidelines. The results indicated that all ARVs need to be assessed for their ecological effects, considering that they all exceeded the EMEA guideline limits (PEC > 0.01 µg L⁻¹). In this sense, three ARVs (namely atazanavir, nevirapine and efavirenz) were selected for the acute and chronic tests with sea urchin (Echinometra lucunter). Furthermore, the Environmental Risk Assessment (ERA) for these three ARVs was also performed by calculating the risk quotient. The acute and chronic toxicity results showed inhibitory concentrations (IC) for the fertilization (IC₅₀; 1 h; range: 11.46–84.61 mg L⁻¹) and for the embryo–larval development (IC₅₀; 42 h; range: 0.52–0.97 mg L⁻¹) of the sea urchin, respectively. Moreover, the ERA showed that these three ARVs are potentially hazardous for aquatic life in Santos Bay, raising concerns about the continuous introduction of ARVs in aquatic ecosystems. The data presented may contribute to the provision of subsidies for the development of monitoring public policies that aim to reduce the introduction of ARVs into the aquatic environment.