Effect of Lonomia obliqua Venom on Human Neutrophils.

The significant incidence of deforestation in South America culminates in the contact of humans with typical forests species. Among these species, one may highlight Lonomia obliqua caterpillar, which, when touched by humans, can poison them through their bristles. Therefore, better acknowledging the mechanisms involved in envenomation caused by Lonomia obliqua caterpillar bristle extract (LOCBE) may contribute to further treatments. Recently, we demonstrated that LOCBE induces a pro-inflammatory profile in endothelial cells; thus, we decided to investigate the effects of LOCBE on human polymorphonuclear neutrophils (PMN), which are the first leukocytes that migrate to the inflammatory focus. Our results showed that treatment with LOCBE induced PMN chemotaxis together with alterations in actin cytoskeleton and focal adhesion kinase (FAK) activation, favoring migration. Concurrently, LOCBE induced PMN adhesion to matrix proteins, such as collagen IV, fibronectin, and fibrinogen. Moreover, we observed that LOCBE attenuated PMN apoptosis and increased reactive oxygen species (ROS) production together with nuclear factor kB (NF-κB) activation-a redox-sensitive transcription factor-as well as interleukin (IL)-1ß and IL-8 release. We call attention to the ROS-dependent effect of LOCBE on increased cell migration once an antioxidant treatment reverted it. In summary, we report that LOCBE activates PMN, inducing pro-inflammatory responses modulated by ROS.

Chia oil induces browning of white adipose tissue in high-fat diet-induced obese mice.

Previous research suggests that omega-3 fatty acids from animal origin may promote the browning of subcutaneous white adipose tissue. We evaluated if supplementation with a plant oil (chia, Salvia hispanica L.) rich in alpha-linolenic fatty acid (C18:3; ω-3) would promote browning and improve glucose metabolism in animals subjected to an obesogenic diet. Swiss male mice (n = 28) were divided into 4 groups: C: control diet; H: high-fat diet; HC: animals in the H group supplemented with chia oil after reaching obesity; HCW: animals fed since weaning on a high-fat diet supplemented with chia oil. Glucose tolerance, inflammatory markers, and expression of genes and proteins involved in the browning process were examined. When supplemented since weaning, chia oil improved glucose metabolism and promoted the browning process and a healthier phenotype. Results of this study suggested that chia oil has potential to protect against the development of obesity-related diseases.

Effects of Lonomia obliqua Venom on Vascular Smooth Muscle Cells: Contribution of NADPH Oxidase-Derived Reactive Oxygen Species.

Envenomation caused by human contact with the caterpillar Lonomia is characterized by deleterious effects on coagulation and patency of blood vessels. The cellular effects induced by Lonomia obliqua venom highlights its capacity to activate endothelial cells, leading to a proinflammatory phenotype. Having more knowledge about the mechanisms involved in envenomation may contribute to better treatment. We aimed to evaluate the effects of Lonomia obliqua caterpillar bristle extract (LOCBE) on vascular smooth muscle cells (VSMC). We observed that LOCBE induced VSMC migration, which was preceded by alterations in actin cytoskeleton dynamics and Focal Adhesion Kinase activation. LOCBE also induced Extracellular Signal-Regulated Kinase (ERK) phosphorylation in VSMC, and the inhibition of this pathway impaired cell proliferation. Stimulation of VSMC with LOCBE triggered reactive oxygen species (ROS) production through the activation of NADPH oxidase. The rapid increase in these ROS further induced mitochondrial ROS production, however only NADPH oxidase-derived ROS were involved in ERK activation in VSMC. We that demonstrated the chemotactic and proliferative effects of LOCBE on VSMC were dependent on ROS production, mainly through NADPH oxidase. Together, the data show that Lonomia obliqua venom can interact with and activate VSMC. These effects rely on ROS production, suggesting new potential targets for treatment against vascular damage during envenomation.

Obesity promotes alterations in iron recycling.

Hepcidin is a key hormone that induces the degradation of ferroportin (FPN), a protein that exports iron from reticuloendothelial macrophages and enterocytes. The aim of the present study was to experimentally evaluate if the obesity induced by a high-fat diet (HFD) modifies the expression of FPN in macrophages and enterocytes, thus altering the iron bioavailability. In order to directly examine changes associated with iron metabolism in vivo, C57BL/6J mice were fed either a control or a HFD. Serum leptin levels were evaluated. The hepcidin, divalent metal transporter-1 (DMT1), FPN and ferritin genes were analyzed by real-time polymerase chain reaction. The amount of iron present in both the liver and spleen was determined by flame atomic absorption spectrometry. Ferroportin localization within reticuloendothelial macrophages was observed by immunofluorescence microscopy. Obese animals were found to exhibit increased hepcidin gene expression, while iron accumulated in the spleen and liver. They also exhibited changes in the sublocation of splenic cellular FPN and a reduction in the FPN expression in the liver and the spleen, while no changes were observed in enterocytes. Possible explanations for the increased hepcidin expression observed in HFD animals may include: increased leptin levels, the liver iron accumulation or endoplasmic reticulum (ER) stress. Together, the results indicated that obesity promotes changes in iron bioavailability, since it altered the iron recycling function.

A pro-inflammatory profile of endothelial cell in Lonomia obliqua envenomation.

Lonomia obliqua envenomation is characterized by intense local inflammatory reaction, which, dependent on the severity of the case, is followed by severe clinical manifestations related to hemorrhagic disorders that can lead to fatal outcome. These effects were imputed to several toxins present in L. obliqua venom, which are responsible for procoagulant, anticoagulant as well as antithrombotic activities, being also able to interfere with vascular cells functions. In this work, the intravital microscopy analysis show that after administration of low doses of L. obliqua venom (1-3 µg/ml) on hamster cheek pouch, there was no alterations neither on arterioles or venules caliber nor in the vascular permeability up to 30 min. However, after 10 min in contact with venom occurred a clear activation in the vascular bed, characterized by an increase in leukocyte rolling and adhesion on endothelium of hamster cheek pouch venules. A confocal analysis of vascular beds, confirmed these results showing an increase in endothelial E-selectin and VCAM-1 expression. The effects of L. obliqua venom on human endothelial cell (EC) in vitro were also investigated. The treatment of EC with venom (1-3 µg/ml) did not affect cell viability. However, at concentrations as low as 3 µg/ml of L. obliqua venom modifies actin cytoskeleton dynamics, and increases focal adhesion contacts, inducing stress fiber formation, focal adhesion kinase (FAK) phosphorylation and its subsequent association to actin. These effects are followed by the activation of NF-κB pathway, a critical signaling in several events associated to vascular inflammation. Accordingly, L. obliqua venom leads to a significant increase in COX-2, NOS-2, HO-1, MMP-2 and MMP-9 expression. Taken together the data show that, even at low concentrations, L. obliqua venom can activate endothelial cells, which assume a pro-inflammatory profile, contributing for local effects and probably also for systemic disturbances due to its ability to modulate the properties of the vascular system.

Aspirin-triggered lipoxin A4 blocks reactive oxygen species generation in endothelial cells: a novel antioxidative mechanism.

Lipoxins and their aspirin-triggered carbon-15 epimers have emerged as mediators of key events in endogenous anti-inflammation and resolution. However, the implication of these novel lipid mediators on cardiovascular diseases such as hypertension, atherosclerosis, and heart failure has not been investigated. One of the major features shared by these pathological conditions is the increased production of reactive oxygen species (ROS) generated by vascular NAD(P)H oxidase activation. In this study, we have examined whether an aspirin-triggered lipoxin A (4) analog (ATL-1) modulates ROS generation in endothelial cells (EC). Pre-treatment of EC with ATL-1 (1 - 100 nM) completely blocked ROS production triggered by different agents, as assessed by dihydrorhodamine 123 and hydroethidine. Furthermore, ATL-1 inhibited the phosphorylation and translocation of the cytosplamic NAD(P)H oxidase subunit p47 (phox) to the cell membrane as well as NAD(P)H oxidase activity. Western blot and immunofluorescence microscopy analyses showed that ATL-1 (100 nM) impaired the redox-sensitive activation of the transcriptional factor NF- kappaB, a critical step in several events associated to vascular pathologies. These results demonstrate that ATL-1 suppresses NAD(P)H oxidase-mediated ROS generation in EC, strongly indicating that lipoxins may play a protective role against the development and progression of cardiovascular diseases.