24 research outputs found
A snake venom secreted phospholipase A2 induces foam cell formation depending on the activation of factors involved in lipid homeostasis
MT-III, a snake venom GIIA sPLA2, which shares structural and functional features with mammalian GIIA sPLA2s, activates
macrophage defense functions including lipid droplet (LDs) formation, organelle involved in both lipid metabolism and
inflammatory processes. Macrophages (MΦs) loaded with LDs, termed foam cells, characterize early blood vessel fatty-streak
lesions during atherosclerosis. However, the factors involved in foam cell formation induced by a GIIA sPLA2 are still unknown.
Here, we investigated the participation of lipid homeostasis-related factors in LD formation induced by MT-III in macrophages.
We found that MT-III activated PPAR-γ and PPAR-β/δ and increased the protein levels of both transcription factors and CD36
in macrophages. Pharmacological interventions evidenced that PPAR-γ, PPAR-β/δ, and CD36 as well as the endoplasmic
reticulum enzymes ACAT and DGAT are essential for LD formation. Moreover, PPAR-β/δ, but not PPAR-γ, is involved in
MT-III-induced PLIN2 protein expression, and both PPAR-β/δ and PPAR-γ upregulated CD36 protein expression, which
contributes to MT-III-induced COX-2 expression. Furthermore, production of 15-d-PGJ2, an activator of PPARs, induced by
MT-III, was dependent on COX-1 being LDs an important platform for generation of this mediator.Fundación de Apoyo a la Investigación del Estado de São Paulo/[00 / 11624-5]/FAPESP/BrasilFundación de Apoyo a la Investigación del Estado de São Paulo/[2011 / 21341-5]/FAPESP/BrasilFundación de Apoyo a la Investigación del Estado de São Paulo/[2014 / 18549-1]/FAPESP/BrasilFundación de Apoyo a la Investigación del Estado de São Paulo/[2010 / 06345-1]/FAPESP/BrasilFundación de Apoyo a la Investigación del Estado de São Paulo/[2015 / 24701-3]/FAPESP/BrasilFundación de Apoyo a la Investigación del Estado de São Paulo/[2013 / 22610-5]/FAPESP/BrasilFundación de Apoyo a la Investigación del Estado de São Paulo/[2010 / 08506-2]/FAPESP/BrasilFundación de Apoyo a la Investigación del Estado de São Paulo/[307379 / 2016-7]/FAPESP/BrasilUCR::VicerrectorÃa de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto Clodomiro Picado (ICP
A secreted phospholipase A2 induces formation of smooth muscle foam cells which trans-differentiate to macrophage-like state
Vascular smooth muscle cells (VSMCs) loaded with lipid droplets (LDs) are markers of
atherosclerosis. In this disease, inflammatory Group IIA-secreted phospholipase A2s (GIIA sPLA2s)
are highly expressed in VSMCs, but their actions in these cells are unknown. Here, we investigated
the ability of myotoxin III (MT-III), an ophidian GIIA sPLA2 sharing structural and functional features
with mammalian GIIA sPLA2s, to induce LD formation and lipid metabolism factors involved in this
e ect. Modulation of VSMC phenotypes by this sPLA2 was also evaluated. Incubation of VSMCs
with MT-III significantly increased the number of LDs. MT-III upregulated scavenger receptor type
1 (SR-A1) and lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) protein expression
and enhanced acetylated-low density lipoprotein (acLDL) uptake by VSMCs, revealing the ability of
a GIIA PLA2 to modulate scavenger receptor activities. MT-III induced translocation and protein
expression of PPAR-
and - / . Inhibition of peroxisome proliferator-activated receptors (PPARs) and
diacylglycerol O-acyltransferase (DGAT) and acyl-CoA:cholesterolacyltransferase (ACAT) enzymes
abrogatedMT-III-induced LD formation. Moreover, in response toMT-III, VSMCs acquired phagocytic
activity and expressed macrophage markers CD68 and MAC-2. In conclusion, MT-III is able to
stimulate VSMCs and recruit factors involved in lipid uptake and metabolism, leading to the formation
of VSMC-derived foam cells with acquisition of macrophage-like markers and functions.Butantan Institute/[FAPESP 00/11624-5]//BrasilUCR::VicerrectorÃa de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto Clodomiro Picado (ICP
Critical role of TLR2 and MyD88 for functional response of macrophages to a group IIA-Secreted phospholipase A2 from snake venom
artÃculo (arbitrado) -- Universidad de Costa Rica, Instituto de Investigaciones Clodomiro Picado. 2014The snake venom MT-III is a group IIA secreted phospholipase A2 (sPLA2) enzyme with functional and structural similarities with mammalian pro-inflammatory sPLA2s of the same group. Previously, we demonstrated that MT-III directly activates the innate inflammatory response of macrophages, including release of inflammatory mediators and formation of lipid droplets (LDs). However, the mechanisms coordinating these processes remain unclear. In the present study, by using TLR22/2 or MyD882/2 or C57BL/6 (WT) male mice, we report that TLR2 and MyD88 signaling have a critical role in MT-III-induced inflammatory response in macrophages. MT-III caused a marked release of PGE2, PGD2, PGJ2, IL-1b and IL-10 and increased the number of LDs in WT macrophages. In MT-III-stimulated TLR22/2 macrophages, formation of LDs and release of eicosanoids and cytokines were abrogated. In MyD882/2 macrophages, MT-III-induced release of PGE2, IL-1b and IL-10 was abrogated, but release of PGD2 and PGJ2 was maintained. In addition, COX-2 protein expression seen in MT-III-stimulated WT macrophages was abolished in both TLR22/2 and MyD882/2 cells, while perilipin 2 expression was abolished only in MyD882/2 cells. We further demonstrated a reduction of saturated, monounsaturated and polyunsaturated fatty acids and a release of the TLR2 agonists palmitic and oleic acid from MT-III-stimulated WT macrophages compared with WT control cells, thus suggesting these fatty acids as major messengers for MT-III-induced engagement of TLR2/MyD88 signaling. Collectively, our findings identify for the first time a TLR2 and MyD88-dependent mechanism that underlies group IIA sPLA2- induced inflammatory response in macrophages.This investigation was supported by research grants from FAPESP, Sao Paulo, Brazil (www.fapesp.br), grants 11/21341-5 and 10/06345-1, INCTTOX, Sao Paulo, Brazil (www.incttox.com.br), grant 573790/2008-6, CNPq PQ, Brazil (www.cnpq.br), grant 306920/2011-5, Brazil, Spanish Ministery of Science and Innovation, Spain (http://web.micinn.es/), grant BFU2010-18826.UCR::VicerrectorÃa de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto Clodomiro Picado (ICP
Study of factors involved in lipid droplets formation induced by a phospholipase A2, isoleted from snake venom: synthesis and lipid metabolismo.
Os venenos de serpentes contêm concentrações elevadas de fosfolipases A2 secretadas (sFLA2), que apresentam homologia com as FLA2s de mamÃferos, cujos nÃveis estão aumentados em doenças inflamatórias. Neste estudo, investigou-se a ativação e a expressão de fatores envolvidos na formação de corpúsculos lipÃdicos (CLs) em células fagociticas e o papel desses fatores na resposta imune inata, induzida pela MT-III, uma sFLA2s de veneno. A MT-III induziu aumento dos nÃveis de triacilglicerol, colesterol e lisofosfolipideos e a ativação e expressão dos fatores PPAR-g, PPAR-d/b, SREBP2 e do CD36. Sob estimulo da MT-III, o receptor PPAR-b/d, as enzimas DGAT, ACAT e FAS foram relevantes para a formação de CLs e para a expressão da PLIN2. O CD36 participa da expressão da COX-2, sem modificar a liberação de PGE2. O TLR2 e a MyD88 foram essenciais para a formação de CLs e sÃntese da IL-1b e IL-10. Ainda, o TLR2 foi relevante para a liberação de PGE2, PGD2 e LTB4, enquanto MyD88 foi fundamental somente para a liberação de PGE2 e expressão da PLIN2, induzidas pela MT-III.Snake venoms contain high concentrations of secreted phospholipase A2 (sPLA2) with homology to mammalian PLA2s, whose levels are elevated in inflammatory diseases. In this study, we investigated activation and expression of factors involved in lipid droplets formation (LDs) and participation that factors in the innate immune response induced by MT-III, sPLA2s from snake venom, in phagocytic cells. MT-III induced increase of triacylglycerol, cholesterol and lysophospholipids levels and activation and expression of factors PPAR-g, PPAR-d/b, SREBP2 and CD36. PPAR-b/d receptor, DGAT, ACAT and FAS enzymes were relevant to LDs formation and critical to PLIN2 expression induced by MT-III. CD36 participates in COX-2 expression without modifying PGE2 release stimulated by MT-III. TLR2 and MyD88 were essential to LDs formation and IL-1b and IL-10 synthesis stimulated by MT-III. Moreover, TLR2 was relevant to PGE2, PGD2 and LTB4 biosynthesis, while MyD88 is essential only for PGE2 release and PLIN2 expression induced by MT-III
A Metalloproteinase Induces an Inflammatory Response in Preadipocytes with the Activation of COX Signalling Pathways and Participation of Endogenous Phospholipases A2
Matrix metalloproteinases (MMPs) are proteolytic enzymes that have been associated with the pathogenesis of inflammatory diseases and obesity. Adipose tissue in turn is an active endocrine organ capable of secreting a range of proinflammatory mediators with autocrine and paracrine properties, which contribute to the inflammation of adipose tissue and adjacent tissues. However, the potential inflammatory effects of MMPs in adipose tissue cells are still unknown. This study investigates the effects of BmooMPα-I, a single-domain snake venom metalloproteinase (SVMP), in activating an inflammatory response by 3T3-L1 preadipocytes in culture, focusing on prostaglandins (PGs), cytokines, and adipocytokines biosynthesis and mechanisms involved in prostaglandin E2 (PGE2) release. The results show that BmooMPα-I induced the release of PGE2, prostaglandin I2 (PGI2), monocyte chemoattractant protein-1 (MCP-1), and adiponectin by preadipocytes. BmooMPα-I-induced PGE2 biosynthesis was dependent on group-IIA-secreted phospholipase A2 (sPLA2-IIA), cytosolic phospholipase A2-α (cPLA2-α), and cyclooxygenase (COX)-1 and -2 pathways. Moreover, BmooMPα-I upregulated COX-2 protein expression but not microsomal prostaglandin E synthase-1 (mPGES-1) expression. In addition, we demonstrate that the enzymatic activity of BmooMPα-I is essential for the activation of prostanoid synthesis pathways in preadipocytes. These data highlight preadipocytes as important targets for metalloproteinases and provide new insights into the contribution of these enzymes to the inflammation of adipose tissue and tissues adjacent to it
Inflammatory Effects of Bothrops Phospholipases A2: Mechanisms Involved in Biosynthesis of Lipid Mediators and Lipid Accumulation
Phospholipases A2s (PLA2s) constitute one of the major protein groups present in the venoms of viperid and crotalid snakes. Snake venom PLA2s (svPLA2s) exhibit a remarkable functional diversity, as they have been described to induce a myriad of toxic effects. Local inflammation is an important characteristic of snakebite envenomation inflicted by viperid and crotalid species and diverse svPLA2s have been studied for their proinflammatory properties. Moreover, based on their molecular, structural, and functional properties, the viperid svPLA2s are classified into the group IIA secreted PLA2s, which encompasses mammalian inflammatory sPLA2s. Thus, research on svPLA2s has attained paramount importance for better understanding the role of this class of enzymes in snake envenomation and the participation of GIIA sPLA2s in pathophysiological conditions and for the development of new therapeutic agents. In this review, we highlight studies that have identified the inflammatory activities of svPLA2s, in particular, those from Bothrops genus snakes, which are major medically important snakes in Latin America, and we describe recent advances in our collective understanding of the mechanisms underlying their inflammatory effects. We also discuss studies that dissect the action of these venom enzymes in inflammatory cells focusing on molecular mechanisms and signaling pathways involved in the biosynthesis of lipid mediators and lipid accumulation in immunocompetent cells
Preadipocytes are target cells for the actions of a representative gIIA phospholipase A2 which triggers proinflammatory pathways related to obesity
Adipose tissue secretes proinflammatory mediators which promote systemic and adipose tissue inflammation seen in obesity. Group IIA (GIIA)-secreted phospholipase A2 (sPLA2) enzymes are found to be elevated in plasma and adipose tissue from obese patients and are active during inflammation, generating proinflammatory mediators, including prostaglandin E2 (PGE2). PGE2 exerts anti-lipolytic actions and increases triacylglycerol levels in adipose tissue. However, the inflammatory actions of GIIA sPLA2s in adipose tissue cells and mechanisms leading to increased PGE2 levels in these cells are unclear. This study investigates the ability of a representative GIIA sPLA2, MT-III, to activate proinflammatory responses in preadipocytes, focusing on the biosynthesis of prostaglandins, adipocytokines and mechanisms involved in these effects. Our results showed that MT-III induced biosynthesis of PGE2, PGI2, MCP-1, IL-6 and gene expression of leptin and adiponectin in preadipocytes. The MT-III-induced PGE2 biosynthesis was dependent on cytosolic PLA2 (cPLA2)-α, cyclooxygenases (COX)-1 and COX-2 pathways and regulated by a positive loop via the EP4 receptor. Moreover, MT-III upregulated COX-2 and microsomal prostaglandin synthase (mPGES)-1 protein expression. MCP-1 biosynthesis induced by MT-III was dependent on the EP4 receptor, while IL-6 biosynthesis was dependent on EP3 receptor engagement by PGE2. These data highlight preadipocytes as targets for GIIA sPLA2s and provide insight into the roles played by this group of sPLA2s in obesityUCR::VicerrectorÃa de Investigación::Unidades de Investigación::Ciencias de la Salud::Instituto Clodomiro Picado (ICP