The cytosolic hyperoxidation-sensitive and -robust Leishmania peroxiredoxins cPRX1 and cPRX2 are both dispensable for parasite infectivity.

Typical two-cysteine peroxiredoxins (2-Cys-PRXs) are H2O2-metabolizing enzymes whose activity relies on two cysteine residues. Protists of the family Trypanosomatidae invariably express one cytosolic 2-Cys-PRX (cPRX1). However, the Leishmaniinae sub-family features an additional isoform (cPRX2), almost identical to cPRX1, except for the lack of an elongated C-terminus with a Tyr-Phe (YF) motif. Previously, cytosolic PRXs were considered vital components of the trypanosomatid antioxidant machinery. Here, we shed new light on the properties, functions and relevance of cPRXs from the human pathogen Leishmania infantum. We show first that LicPRX1 is sensitive to inactivation by hyperoxidation, mirroring other YF-containing PRXs participating in redox signaling. Using genetic fusion constructs with roGFP2, we establish that LicPRX1 and LicPRX2 can act as sensors for H2O2 and oxidize protein thiols with implications for signal transduction. Third, we show that while disrupting the LicPRX-encoding genes increases susceptibility of L. infantum promastigotes to external H2O2in vitro, both enzymes are dispensable for the parasites to endure the macrophage respiratory burst, differentiate into amastigotes and initiate in vivo infections. This study introduces a novel perspective on the functions of trypanosomatid cPRXs, exposing their dual roles as both peroxidases and redox sensors. Furthermore, the discovery that Leishmania can adapt to the absence of both enzymes has significant implications for our understanding of Leishmania infections and their treatment. Importantly, it questions the conventional notion that the oxidative response of macrophages during phagocytosis is a major barrier to infection and the suitability of cPRXs as drug targets for leishmaniasis.

Structural, functional and behavioral impact of allergic rhinitis on olfactory pathway and prefrontal cortex.

BACKGROUND: Allergic rhinitis (AR) has been identified as a cause of olfactory dysfunction. Beyond the classic symptoms, AR has been associated with altered sleep patterns, a decline in cognitive performance and higher likelihood of depression and anxiety. The olfactory pathway has been postulated to be a possible link between nasal inflammation and central nervous system (CNS) modifications. Thus, we aimed to investigate the structural, functional and behavioral changes in the olfactory pathway and related areas in an animal model of AR. METHODS: AR was induced in adult Wistar rats by ovalbumin sensitization and challenge. Following olfactory and behavioral tests we investigated the synaptic structure of the olfactory bulb (OB), anterior olfactory nuclei (AON), piriform cortex and prefrontal cortex (PFC), by immunofluorescence detection of synaptophysin (Syn) and glutamatergic, GABAergic and dopaminergic neuronal markers. RESULTS: We detected a significant decrease in Syn in the glomerular layer (GL) of OB and in the PFC of the AR group. Additionally, the optical density of GAD67 and VGLUT2 was reduced in the OB, AON and PFC, compared to controls. The behavioral tests demonstrated olfactory dysfunction and reduced male aggressiveness in AR rats, but we did not find any difference in the cognition and anxiety-like behavior. CONCLUSIONS: We confirmed olfactory dysfunction in a rat model of AR and we identified modifications in synaptic activity by reduction of Syn optical density in the GL of the OB and in the PFC. This was accompanied by structural changes in glutamatergic and GABAergic activity in essential components of the olfactory pathway and PFC.

Chemical characterization and bioactive potential of Artemisia campestris L. subsp. maritima (DC) Arcang. essential oil and hydrodistillation residual water.

ETHNOPHARMACOLOGICAL RELEVANCE: Artemisia campestris L. is widely used in traditional medicine for their anti-inflammatory, antirheumatic, antimicrobial and antioxidant properties. A. campestris subsp. maritima Arcang., a halophyte plant ("madorneira" or "erva-lombrigueira" in Portugal), is traditionally used for gastric disorders, rheumatism and hypertension. AIM OF THE STUDY: The present study aims to characterize the essential oil (EO) and the hydrodistillation residual water (HRW), a by-product of the EO production, of Artemisia campestris subsp. maritima from Portugal and evaluate the antioxidant, antifungal, anti-inflammatory and wound healing activities of both extracts at concentrations without toxicity. MATERIALS AND METHODS: The phenolic profile of HRW was determined by HPLC-PDA-ESI/MSn and the EO was analyzed by gas chromatography (GC-FID and GC-MS). The antioxidant activity of both extracts were determined by several assays (ABTS, NO FRAP, ß-carotene and DPPH). The antifungal activity (MIC and MLC) was evaluated against yeasts, dermatophytes and Aspergillus strains using broth macrodilution methods. The anti-inflammatory potential was determined measuring the nitric oxide (NO) production by stimulated mouse leukemic macrophages (RAW 264.7). Cell viability was evaluated for RAW 264.7 and mouse fibroblasts (NIH/3T3). The wound healing activity was evaluated in mouse fibroblasts (NIH/3T3) by the scratch assay. RESULTS: The HRW is mainly characterized by hydroxycinnamic acids and the essential oil is characterized by high amounts of ß-pinene (54.5%), cadin-4-en-7-ol (9.5%), Z-ß-ocimene (6.0%) and Ƴ-terpinene (4.6%). Both extracts showed high antioxidant potential in different assays. Additionally, only the hydrodistillation residual water showed anti-inflammatory activity (IC50 of 330 µg/mL). On the other hand, only the EO showed antifungal activity, particularly against Epidermophyton floccosum (MIC and MLC values of 0.16 µL/mL), and wound healing activity. Bothe extracts were not cytotoxic to macrophages CONCLUSIONS: The by-product HRW contains safe bioactive compounds with antioxidant and anti-inflammatory effect and the EO shows antioxidant properties, antifungal activity against dermatophytes and wound healing effect in skin cells. Overall, our results support the interest and economic value of two extracts obtained from a Portuguese native species and provide scientific validation to some of its traditional uses.

Leishmania infantum Enhances Migration of Macrophages via a Phosphoinositide 3-Kinase γ-Dependent Pathway.

Leishmania infantum (L. infantum) and Leishmania major (L. major) are phylogenetically related protozoan parasites that cause different pathologies in humans (visceral and cutaneous infections, respectively). Here, we report on how these obligatory intracellular pathogens differentially affect the migration of macrophages. Resorting to gap closure assays of infected murine bone marrow derived macrophages, we observed that L. infantum enhances the mobility of these cells. This is not the case of L. major, whose impact on macrophage migration is null. Resorting to kinase inhibition assays, we witnessed that chemical inhibition of phosphoinositide 3-kinase-γ (PI3Kγ) critically impairs cell mobility in all experimental conditions. Importantly, the blockade of tyrosine kinases with dasatinib also slows down naïve and L. major-parasitized cells but not macrophages exposed to L. infantum. The dasatinib-resistant phenotype of L. infantum-infected macrophages aligns with the hypothesis that this parasite invokes a tyrosine kinase-independent pathway to increase the PI3Kγ activity of macrophages and enhance migration.

Functional insight into the glycosomal peroxiredoxin of Leishmania.

Glycosomes of trypanosomatids are peroxisome-like organelles comprising unique metabolic features, among which the lack of the hallmark peroxisomal enzyme catalase. The absence of this highly efficient peroxidase from glycosomes is presumably compensated by other antioxidants, peroxidases of the peroxiredoxin (PRX) family being the most promising candidates for this function. Here, we follow on this premise and investigate the product of a Leishmania infantum gene coding for a putative glycosomal PRX (LigPRX). First, we demonstrate that LigPRX localizes to glycosomes, resorting to indirect immunofluorescence analysis. Second, we prove that purified recombinant LigPRX is an active peroxidase in vitro. Third, we generate viable LigPRX-depleted L. infantum promastigotes by classical homologous recombination. Surprisingly, phenotypic analysis of these knockout parasites revealed that promastigote survival, replication, and protection from oxidative and nitrosative insults can proceed normally in the absence of LigPRX. Noticeably, we also witness that LigPRX-depleted parasites can infect and thrive in mice to the same extent as wild type parasites. Overall, by disclosing the dispensable character of the glycosomal peroxiredoxin in L. infantum, this work excludes this enzyme from being a key component of the glycosomal hydroperoxide metabolism and contemplates alternative players for this function.