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Moreira V, Leiguez E, Janovits PM, Maia-Marques R, Fernandes CM, Teixeira C. Inflammatory Effects of Bothrops Phospholipases A 2: Mechanisms Involved in Biosynthesis of Lipid Mediators and Lipid Accumulation. Toxins (Basel) 2021; 13:toxins13120868. [PMID: 34941706 PMCID: PMC8709003 DOI: 10.3390/toxins13120868] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Revised: 11/19/2021] [Accepted: 11/30/2021] [Indexed: 02/07/2023] Open
Abstract
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.
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Affiliation(s)
- Vanessa Moreira
- Departamento de Farmacologia, Escola Paulista de Medicina, Universidade Federal de Sao Paulo, Sao Paulo 04044-020, Brazil;
| | - Elbio Leiguez
- Laboratório de Farmacologia, Instituto Butantan, Sao Paulo 05503-900, Brazil; (E.L.); (P.M.J.); (R.M.-M.); (C.M.F.)
| | - Priscila Motta Janovits
- Laboratório de Farmacologia, Instituto Butantan, Sao Paulo 05503-900, Brazil; (E.L.); (P.M.J.); (R.M.-M.); (C.M.F.)
| | - Rodrigo Maia-Marques
- Laboratório de Farmacologia, Instituto Butantan, Sao Paulo 05503-900, Brazil; (E.L.); (P.M.J.); (R.M.-M.); (C.M.F.)
| | - Cristina Maria Fernandes
- Laboratório de Farmacologia, Instituto Butantan, Sao Paulo 05503-900, Brazil; (E.L.); (P.M.J.); (R.M.-M.); (C.M.F.)
| | - Catarina Teixeira
- Laboratório de Farmacologia, Instituto Butantan, Sao Paulo 05503-900, Brazil; (E.L.); (P.M.J.); (R.M.-M.); (C.M.F.)
- Correspondence:
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Cytosolic phospholipase A 2-α participates in lipid body formation and PGE 2 release in human neutrophils stimulated with an L-amino acid oxidase from Calloselasma rhodostoma venom. Sci Rep 2020; 10:10976. [PMID: 32620771 PMCID: PMC7334223 DOI: 10.1038/s41598-020-67345-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 06/05/2020] [Indexed: 12/02/2022] Open
Abstract
Cr-LAAO, an l-amino acid oxidase isolated from Calloselasma rhodosthoma snake venom, has been demonstrated as a potent stimulus for neutrophil activation and inflammatory mediator production. However, the mechanisms involved in Cr-LAAO induced neutrophil activation has not been well characterized. Here we investigated the mechanisms involved in Cr-LAAO-induced lipid body (also known as lipid droplet) biogenesis and eicosanoid formation in human neutrophils. Using microarray analysis, we show for the first time that Cr-LAAO plays a role in the up-regulation of the expression of genes involved in lipid signalling and metabolism. Those include different members of phospholipase A2, mostly cytosolic phospholipase A2-α (cPLA2-α); and enzymes involved in prostaglandin synthesis including cyclooxygenases 2 (COX-2), and prostaglandin E synthase (PTGES). In addition, genes involved in lipid droplet formation, including perilipin 2 and 3 (PLIN 2 and 3) and diacylglycerol acyltransferase 1 (DGAT1), were also upregulated. Furthermore, increased phosphorylation of cPLA2-α, lipid droplet biogenesis and PGE2 synthesis were observed in human neutrophils stimulated with Cr-LAAO. Treatment with cPLA2-α inhibitor (CAY10650) or DGAT-1 inhibitor (A922500) suppressed lipid droplets formation and PGE2 secretion. In conclusion, we demonstrate for the first time the effects of Cr-LAAO to regulate neutrophil lipid metabolism and signalling.
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Crotalus durissus ruruima Snake Venom and a Phospholipase A 2 Isolated from This Venom Elicit Macrophages to Form Lipid Droplets and Synthesize Inflammatory Lipid Mediators. J Immunol Res 2019; 2019:2745286. [PMID: 31781674 PMCID: PMC6875421 DOI: 10.1155/2019/2745286] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 05/13/2019] [Accepted: 09/03/2019] [Indexed: 12/15/2022] Open
Abstract
Viper snake Crotalus durissus ruruima (Cdr) is a subspecies found in northern area of Brazil. Among the snakes of Crotalus genus subspecies, the venom of Cdr presents highest level of crotoxin, which is the major component of Crotalus snake venoms, formed by two subunits (crotapotin and a phospholipase A2 named CBr) and presents potent neurotoxic activity. Curiously, the venom of C. d. ruruima (CdrV) is better neutralized by antibothropic than by anticrotalic serum, strongly suggesting that this venom has similarities with venom of Bothrops genus snakes with regard to the ability to induce inflammation. Macrophages are cells with a central role in inflammatory and immunological responses. Upon inflammatory stimuli, these cells exhibit increased numbers of lipid droplets, which are key organelles in the synthesis and release of inflammatory mediators. However, the effects of CdrV and CBr in macrophage functions are unknown. We herein investigated the ability of CdrV and CBr to activate macrophages with focus on the formation of lipid droplets (LDs), synthesis of lipid mediators, and mechanisms involved in these effects. The involvement of LDs in PGE2 biosynthesis was also assessed. Stimulation of murine macrophages with CdrV and CBr induced an increased number of LDs and release of prostanoids (PGE2, PGD2, and TXB2). Neither CdrV nor CBr induced the expression of COX-1 and COX-2 by macrophages. LDs induced by both CdrV and CBr are associated to PLIN2 recruitment and expression and were shown to be dependent on COX-1, but not COX-2 activity. Moreover, PGE2 colocalized to CdrV- and CBr-induced LDs, revealing the role of these organelles as sites for the synthesis of prostanoids. These results evidence, for the first time, the ability of a whole snake venom to induce formation of LDs and the potential role of these organelles for the production of inflammatory mediators during envenomation by Crotalus snakes.
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Ferraz CR, Arrahman A, Xie C, Casewell NR, Lewis RJ, Kool J, Cardoso FC. Multifunctional Toxins in Snake Venoms and Therapeutic Implications: From Pain to Hemorrhage and Necrosis. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00218] [Citation(s) in RCA: 80] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
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A snake venom group IIA PLA 2 with immunomodulatory activity induces formation of lipid droplets containing 15-d-PGJ 2 in macrophages. Sci Rep 2017. [PMID: 28642580 PMCID: PMC5481388 DOI: 10.1038/s41598-017-04498-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Crotoxin B (CB) is a catalytically active group IIA sPLA2 from Crotalus durissus terrificus snake venom. In contrast to most GIIA sPLA2s, CB exhibits anti-inflammatory effects, including the ability to inhibit leukocyte functions. Lipid droplets (LDs) are lipid-rich organelles associated with inflammation and recognized as a site for the synthesis of inflammatory lipid mediators. Here, the ability of CB to induce formation of LDs and the mechanisms involved in this effect were investigated in isolated macrophages. The profile of CB-induced 15-d-PGJ2 (15-Deoxy-Delta-12,14-prostaglandin J2) production and involvement of LDs in 15-d-PGJ2 biosynthesis were also investigated. Stimulation of murine macrophages with CB induced increased number of LDs and release of 15-d-PGJ2. LDs induced by CB were associated to PLIN2 recruitment and expression and required activation of PKC, PI3K, MEK1/2, JNK, iPLA2 and PLD. Both 15-d-PGJ2 and COX-1 were found in CB-induced LDs indicating that LDs contribute to the inhibitory effects of CB by acting as platform for synthesis of 15-d-PGJ2, a pro-resolving lipid mediator. Together, our data indicate that an immunomodulatory GIIA sPLA2 can directly induce LD formation and production of a pro-resolving mediator in an inflammatory cell and afford new insights into the roles of LDs in resolution of inflammatory processes.
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Dias RG, Sampaio SC, Sant'Anna MB, Cunha FQ, Gutiérrez JM, Lomonte B, Cury Y, Picolo G. Articular inflammation induced by an enzymatically-inactive Lys49 phospholipase A 2: activation of endogenous phospholipases contributes to the pronociceptive effect. J Venom Anim Toxins Incl Trop Dis 2017; 23:18. [PMID: 28344594 PMCID: PMC5364601 DOI: 10.1186/s40409-017-0104-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Accepted: 02/24/2017] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND Arthritis is a set of inflammatory conditions that induce aching, stiffness, swelling, pain and may cause functional disability with severe consequences to the patient's lives. These are multi-mediated pathologies that cannot be effectively protected and/or treated. Therefore, the aim of this study was to establish a new model of acute arthritis, using a Lys49-PLA2 (Bothrops asper myotoxin II; MT-II) to induce articular inflammation. METHODS The articular inflammation was induced by MT-II (10 μg/joint) injection into the left tibio-tarsal or femoral-tibial-patellar joints. Cellular influx was evaluated counting total and differential cells that migrated to the joint. The plasma extravasation was determined using Evans blue dye. The edematogenic response was evaluated measuring the joint thickness using a caliper. The articular hypernociception was determined by a dorsal flexion of the tibio-tarsal joint using an electronic pressure-meter test. The mediators involved in the articular hypernociception were evaluated using receptor antagonists and enzymatic inhibitors. RESULTS Plasma extravasation in the knee joints was observed 5 and 15 min after MT-II (10 μg/joint) injection. MT-II also induced a polymorphonuclear cell influx into the femoral-tibial-patellar joints observed 8 h after its injection, a period that coincided with the peak of the hyperalgesic effect. Hyperalgesia was inhibited by the pretreatment of the animals with cyclooxygenase inhibitor indomethacin, with type-2 cyclooxygenase inhibitor celecoxib, with AACOCF3 and PACOCF3, inhibitors of cytosolic and Ca2+-independent PLA2s, respectively, with bradykinin B2 receptor antagonist HOE 140, with antibodies against TNFα, IL-1β, IL-6 and CINC-1 and with selective ET-A (BQ-123) and ET-B (BQ-788) endothelin receptors antagonists. The MT-II-induced hyperalgesia was not altered by the lipoxygenase inhibitor zileuton, by the bradykinin B1 receptor antagonist Lys-(Des-Arg9,Leu8)-bradykinin, by the histamine and serotonin antagonists promethazine and methysergide, respectively, by the nitric oxide inhibitor LNMMA and by the inhibitor of matrix 1-, 2-, 3-, 8- and 9- metalloproteinases GM6001 (Ilomastat). CONCLUSION These results demonstrated the multi-mediated characteristic of the articular inflammation induced by MT-II, which demonstrates its relevance as a model for arthritis mechanisms and treatment evaluation.
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Affiliation(s)
- Renata Gonçalves Dias
- Special Laboratory of Pain and Signaling, Butantan Institute, Av. Vital Brazil, 1500, São Paulo, SP CEP 05503-900 Brazil.,Healthy Sciences Institute, Paulista University (UNIP), São Paulo, SP Brazil
| | - Sandra Coccuzzo Sampaio
- Laboratory of Pathophysiology, Butantan Institute, São Paulo, SP Brazil.,Department of Pharmacology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, SP Brazil
| | - Morena Brazil Sant'Anna
- Special Laboratory of Pain and Signaling, Butantan Institute, Av. Vital Brazil, 1500, São Paulo, SP CEP 05503-900 Brazil
| | - Fernando Queiroz Cunha
- Department of Pharmacology, Faculty of Medicine of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP Brazil
| | - José María Gutiérrez
- Clodomiro Picado Institute, Faculty of Microbiology, University of Costa Rica, San José, Costa Rica
| | - Bruno Lomonte
- Clodomiro Picado Institute, Faculty of Microbiology, University of Costa Rica, San José, Costa Rica
| | - Yara Cury
- Special Laboratory of Pain and Signaling, Butantan Institute, Av. Vital Brazil, 1500, São Paulo, SP CEP 05503-900 Brazil
| | - Gisele Picolo
- Special Laboratory of Pain and Signaling, Butantan Institute, Av. Vital Brazil, 1500, São Paulo, SP CEP 05503-900 Brazil
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Rucavado A, Nicolau CA, Escalante T, Kim J, Herrera C, Gutiérrez JM, Fox JW. Viperid Envenomation Wound Exudate Contributes to Increased Vascular Permeability via a DAMPs/TLR-4 Mediated Pathway. Toxins (Basel) 2016; 8:toxins8120349. [PMID: 27886127 PMCID: PMC5198544 DOI: 10.3390/toxins8120349] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 11/15/2016] [Accepted: 11/17/2016] [Indexed: 01/21/2023] Open
Abstract
Viperid snakebite envenomation is characterized by inflammatory events including increase in vascular permeability. A copious exudate is generated in tissue injected with venom, whose proteomics analysis has provided insights into the mechanisms of venom-induced tissue damage. Hereby it is reported that wound exudate itself has the ability to induce increase in vascular permeability in the skin of mice. Proteomics analysis of exudate revealed the presence of cytokines and chemokines, together with abundant damage associated molecular pattern molecules (DAMPs) resulting from both proteolysis of extracellular matrix and cellular lysis. Moreover, significant differences in the amounts of cytokines/chemokines and DAMPs were detected between exudates collected 1 h and 24 h after envenomation, thus highlighting a complex temporal dynamic in the composition of exudate. Pretreatment of mice with Eritoran, an antagonist of Toll-like receptor 4 (TLR4), significantly reduced the exudate-induced increase in vascular permeability, thus suggesting that DAMPs might be acting through this receptor. It is hypothesized that an "Envenomation-induced DAMPs cycle of tissue damage" may be operating in viperid snakebite envenomation through which venom-induced tissue damage generates a variety of DAMPs which may further expand tissue alterations.
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Affiliation(s)
- Alexandra Rucavado
- Instituto Clodomiro Picado, Facultad de Microbiología Universidad de Costa Rica, San José 11501-2060, Costa Rica.
| | - Carolina A Nicolau
- Laboratório de Toxinologia, Instituto Oswaldo Cruz, Rio de Janeiro CEP 21040-360, Brazil.
| | - Teresa Escalante
- Instituto Clodomiro Picado, Facultad de Microbiología Universidad de Costa Rica, San José 11501-2060, Costa Rica.
| | - Junho Kim
- Department of Fine Chemistry & New Materials, Sangji University, Wonju-si, Kangwon-do 220-702, Korea.
| | - Cristina Herrera
- Instituto Clodomiro Picado, Facultad de Microbiología Universidad de Costa Rica, San José 11501-2060, Costa Rica.
- Facultad de Farmacia, Universidad de Costa Rica, San José 11501-2060, Costa Rica.
| | - José María Gutiérrez
- Instituto Clodomiro Picado, Facultad de Microbiología Universidad de Costa Rica, San José 11501-2060, Costa Rica.
| | - Jay W Fox
- Department of Microbiology, Immunology and Cancer Biology, University of Virginia School of Medicine, P.O. Box 800734, Charlottesville, VA 22908, USA.
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de Menezes RRPPB, Mello CP, Lima DB, Tessarolo LD, Sampaio TL, Paes LCF, Alves NTQ, Assis Junior EM, Lima Junior RCP, Toyama MH, Martins AMC. Involvement of Nitric Oxide on Bothropoides insularis Venom Biological Effects on Murine Macrophages In Vitro. PLoS One 2016; 11:e0151029. [PMID: 26974665 PMCID: PMC4790960 DOI: 10.1371/journal.pone.0151029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2015] [Accepted: 02/23/2016] [Indexed: 11/30/2022] Open
Abstract
Viperidae venom has several local and systemic effects, such as pain, edema, inflammation, kidney failure and coagulopathy. Additionally, bothropic venom and its isolated components directly interfere on cellular metabolism, causing alterations such as cell death and proliferation. Inflammatory cells are particularly involved in pathological envenomation mechanisms due to their capacity of releasing many mediators, such as nitric oxide (NO). NO has many effects on cell viability and it is associated to the development of inflammation and tissue damage caused by Bothrops and Bothropoides venom. Bothropoides insularis is a snake found only in Queimada Grande Island, which has markedly toxic venom. Thus, the aim of this work was to evaluate the biological effects of Bothropoides insularis venom (BiV) on RAW 264.7 cells and assess NO involvement. The venom was submitted to colorimetric assays to identify the presence of some enzymatic components. We observed that BiV induced H2O2 production and showed proteolytic and phospholipasic activities. RAW 264.7 murine macrophages were incubated with different concentrations of BiV and then cell viability was assessed by MTT reduction assay after 2, 6, 12 and 24 hours of incubation. A time- and concentration-dependent effect was observed, with a tendency to cell proliferation at lower BiV concentrations and cell death at higher concentrations. The cytotoxic effect was confirmed after lactate dehydrogenase (LDH) measurement in the supernatant from the experimental groups. Flow cytometry analyses revealed that necrosis is the main cell death pathway caused by BiV. Also, BiV induced NO release. The inhibition of both proliferative and cytotoxic effects with L-NAME were demonstrated, indicating that NO is important for these effects. Finally, BiV induced an increase in iNOS expression. Altogether, these results demonstrate that B. insularis venom have proliferative and cytotoxic effects on macrophages, with necrosis participation. We also suggest that BiV acts by inducing iNOS expression and causing NO release.
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Affiliation(s)
- Ramon R. P. P. B. de Menezes
- Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, Ceará, Brazil
| | - Clarissa P. Mello
- Department of Clinical and Toxicological Analysis, Federal University of Ceará, Fortaleza, Ceará, Brazil
| | - Dânya B. Lima
- Department of Clinical and Toxicological Analysis, Federal University of Ceará, Fortaleza, Ceará, Brazil
| | - Louise D. Tessarolo
- Department of Clinical and Toxicological Analysis, Federal University of Ceará, Fortaleza, Ceará, Brazil
| | - Tiago Lima Sampaio
- Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, Ceará, Brazil
| | - Lívia C. F. Paes
- Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, Ceará, Brazil
| | - Natacha T. Q. Alves
- Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, Ceará, Brazil
| | | | - Roberto C. P. Lima Junior
- Department of Physiology and Pharmacology, School of Medicine, Federal University of Ceará, Fortaleza, Ceará, Brazil
| | - Marcos H. Toyama
- São Vicente Unit, Paulista Coastal Campus, São Paulo State University (UNESP), São Paulo, Brazil
| | - Alice M. C. Martins
- Department of Clinical and Toxicological Analysis, Federal University of Ceará, Fortaleza, Ceará, Brazil
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Activation of J77A.1 macrophages by three phospholipases A2 isolated from Bothrops atrox snake venom. BIOMED RESEARCH INTERNATIONAL 2014; 2014:683123. [PMID: 24592395 PMCID: PMC3921937 DOI: 10.1155/2014/683123] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/04/2013] [Revised: 11/18/2013] [Accepted: 11/18/2013] [Indexed: 12/22/2022]
Abstract
In the present study, we investigated the in vitro effects of two basic myotoxic phospholipases A2 (PLA2), BaTX-I, a catalytically inactive Lys-49 variant, and BaTX-II, a catalytically active Asp-49, and of one acidic myotoxic PLA2, BaPLA2, a catalytically active Asp-49, isolated from Bothrops atrox snake venom, on the activation of J774A.1 macrophages. At noncytotoxic concentrations, the toxins did not affect the adhesion of the macrophages, nor their ability to detach. The data obtained showed that only BaTX-I stimulated complement receptor-mediated phagocytosis. However, BaTX-I, BaTX-II, and BaPLA2 induced the release of the superoxide anion by J774A.1 macrophages. Additionally, only BaTX-I raised the lysosomal volume of macrophages after 15 min of incubation. After 30 min, all the phospholipases increased this parameter, which was not observed within 60 min. Moreover, BaTX-I, BaTX-II, and BaPLA2 increased the number of lipid bodies on macrophages submitted to phagocytosis and not submitted to phagocytosis. However, BaTX-II and BaPLA2 induced the release of TNF-α by J774A.1 macrophages. Taken together, the data show that, despite differences in enzymatic activity, the three toxins induced inflammatory events and whether the enzyme is acidic or basic does not seem to contribute to these effects.
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McCurdy CE, Klemm DJ. Adipose tissue insulin sensitivity and macrophage recruitment: Does PI3K pick the pathway? Adipocyte 2013; 2:135-42. [PMID: 23991359 PMCID: PMC3756101 DOI: 10.4161/adip.24645] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2012] [Revised: 04/09/2013] [Accepted: 04/10/2013] [Indexed: 02/06/2023] Open
Abstract
In the United States, obesity is a burgeoning health crisis, with over 30% of adults and nearly 20% of children classified as obese. Insulin resistance, a common metabolic complication associated with obesity, significantly increases the risk of developing metabolic diseases such as hypertension, coronary heart disease, stroke, type 2 diabetes, and certain cancers. With the seminal finding that obese adipose tissue harbors cytokine secreting immune cells, obesity-related research over the past decade has focused on understanding adipocyte–macrophage crosstalk and its impact on systemic insulin sensitivity. Indeed, adipose tissue has emerged as a central mediator of obesity- and diet-induced insulin resistance. In this mini-review, we focus on a potential role of adipose tissue phosphoinositide 3-kinase (PI3K) as a point of convergence of cellular signaling pathways that integrates nutrient sensing and inflammatory signaling to regulate tissue insulin sensitivity.
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