scholarly journals Amplification of Snake Venom Toxicity by Endogenous Signaling Pathways

Toxins ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 68 ◽  
Author(s):  
Philip E. Bickler
Keyword(s):  
Arachidonic Acid ◽  
Snake Venom ◽  
Cell Injury ◽  
Tissue Injury ◽  
Organ Injury ◽  
Active Components ◽  
Venom Protein ◽  
Signaling Systems ◽  
Prey Protein ◽  
Venom Dose

The active components of snake venoms encompass a complex and variable mixture of proteins that produce a diverse, but largely stereotypical, range of pharmacologic effects and toxicities. Venom protein diversity and host susceptibilities determine the relative contributions of five main pathologies: neuromuscular dysfunction, inflammation, coagulopathy, cell/organ injury, and disruption of homeostatic mechanisms of normal physiology. In this review, we describe how snakebite is not only a condition mediated directly by venom, but by the amplification of signals dysregulating inflammation, coagulation, neurotransmission, and cell survival. Although venom proteins are diverse, the majority of important pathologic events following envenoming follow from a small group of enzyme-like activities and the actions of small toxic peptides. This review focuses on two of the most important enzymatic activities: snake venom phospholipases (svPLA2) and snake venom metalloproteases (svMP). These two enzyme classes are adept at enabling venom to recruit homologous endogenous signaling systems with sufficient magnitude and duration to produce and amplify cell injury beyond what would be expected from the direct impact of a whole venom dose. This magnification produces many of the most acutely important consequences of envenoming as well as chronic sequelae. Snake venom PLA2s and MPs enzymes recruit prey analogs of similar activity. The transduction mechanisms that recruit endogenous responses include arachidonic acid, intracellular calcium, cytokines, bioactive peptides, and possibly dimerization of venom and prey protein homologs. Despite years of investigation, the precise mechanism of svPLA2-induced neuromuscular paralysis remains incomplete. Based on recent studies, paralysis results from a self-amplifying cycle of endogenous PLA2 activation, arachidonic acid, increases in intracellular Ca2+ and nicotinic receptor deactivation. When prolonged, synaptic suppression supports the degeneration of the synapse. Interaction between endothelium-damaging MPs, sPLA2s and hyaluronidases enhance venom spread, accentuating venom-induced neurotoxicity, inflammation, coagulopathy and tissue injury. Improving snakebite treatment requires new tools to understand direct and indirect effects of envenoming. Homologous PLA2 and MP activities in both venoms and prey/snakebite victim provide molecular targets for non-antibody, small molecule agents for dissecting mechanisms of venom toxicity. Importantly, these tools enable the separation of venom-specific and prey-specific pathological responses to venom.

scholarly journals Diagnostic Significance of Serum Galectin-3 in Hospitalized Patients with COVID-19—A Preliminary Study

Biomolecules ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1136
Author(s):  
Beata Kuśnierz-Cabala ◽  
Barbara Maziarz ◽  
Paulina Dumnicka ◽  
Marcin Dembiński ◽  
Maria Kapusta ◽  
...  
Keyword(s):  
Diagnostic Accuracy ◽  
Hospital Stay ◽  
Tissue Injury ◽  
Immunological Response ◽  
Organ Injury ◽  
Quantitative Detection ◽  
Serum Samples ◽  
Diagnostic Significance ◽  
Galectin 3 ◽  
Preliminary Study

Severe coronavirus disease 2019 (COVID-19) is associated with hyperinflammation leading to organ injury, including respiratory failure. Galectin-3 was implicated in innate immunological response to infections and in chronic fibrosis. The aim of our preliminary study was the assessment of the diagnostic utility of serum galectin-3 in patients with COVID-19. The prospective observational study included adult patients admitted with active COVID-19 and treated in tertiary hospital between June and July 2020. The diagnosis was confirmed by the quantitative detection of nucleic acid of severe acute respiratory syndrome coronavirus 2 in nasopharyngeal swabs. Galectin-3 was measured by enzyme immunoassay in serum samples obtained during the first five days of hospital stay. We included 70 patients aged 25 to 73 years; 90% had at least one comorbidity. During the hospital stay, 32.9% were diagnosed with COVID-19 pneumonia and 12.9% required treatment in the intensive care unit (ICU). Serum galectin-3 was significantly increased in patients who developed pneumonia, particularly those who required ICU admission. Positive correlations were found between galectin-3 and inflammatory markers (interleukin-6, C-reactive protein, ferritin, pentraxin-3), a marker of endothelial injury (soluble fms-like tyrosine kinase-1), and a range of tissue injury markers. Serum galectin-3 enabled the diagnosis of pneumonia with moderate diagnostic accuracy and the need for ICU treatment with high diagnostic accuracy. Our findings strengthen the hypothesis that galectin-3 may be involved in severe COVID-19. Further studies are planned to confirm the preliminary results and to verify possible associations of galectin-3 with long-term consequences of COVID-19, including pulmonary fibrosis.

Trans-dentinal Stimulation of Tertiary Dentinogenesis

2001 ◽  
Vol 15 (1) ◽  
pp. 51-54 ◽  
Author(s):  
A.J. Smith ◽  
P.E. Murray ◽  
A.J. Sloan ◽  
J.B. Matthews ◽  
S. Zhao
Keyword(s):  
Growth Factors ◽  
Tissue Injury ◽  
Careful Consideration ◽  
Active Components ◽  
Restorative Treatment ◽  
Cellular Events ◽  
Dentin Matrix ◽  
Dentin Thickness ◽  
Tertiary Dentinogenesis ◽  
Stimulation Of

Trans-dentinal stimulation of tertiary dentinogenesis has long been recognized, and has traditionally been ascribed to diffusion of irritant substances arising during injury and restorative treatment. Identification of bio-active components, especially growth factors including TGF-βs, sequestered within dentin matrix provides a new explanation for cellular signaling during tertiary dentinogenesis. Both isolated dentin matrix components and pure growth factors (TGF-βs) have been shown to signal cellular events leading to reactionary and reparative tertiary dentinogenesis. Release of these bio-active components from dentin matrix may arise during carious attack and other injury to the tissue, and also during subsequent surgical intervention and restoration of the tooth. Both cavity-conditioning agents and leaching from restorative materials may contribute to release of these components. Distance of diffusion, as determined by cavity residual dentin thickness, and other restorative parameters may influence the signaling process after release of these components. Careful consideration of the interplay between tissue injury and surgical and restorative material factors is required for optimum exploitation of the exquisite regenerative capacity of dentin-pulp for more biological approaches to clinical treatment of dental disease.

Neutrophil-induced liver cell injury in endotoxin shock is a CD11b/CD18-dependent mechanism

1991 ◽  
Vol 261 (6) ◽  
pp. G1051-G1056 ◽  
Author(s):  
H. Jaeschke ◽  
A. Farhood ◽  
C. W. Smith
Keyword(s):  
Liver Injury ◽  
Cell Injury ◽  
Tissue Injury ◽  
Oxidant Stress ◽  
Parenchymal Cell ◽  
Endotoxin Shock ◽  
Liver Cell Injury ◽  
Integrin Family ◽  
Dependent Mechanism

To investigate the role of neutrophils (PMNs) and PMN-dependent adhesion molecules in the pathogenesis of liver injury in a model of endotoxin shock, male ICR mice received a dose of 700 mg/kg galactosamine and 100 micrograms/kg Salmonella abortus equi endotoxin. PMNs accumulated continuously in the liver, reaching values of 446 +/- 71 PMNs/50 high-power fields at 9 h (basal value 18 +/- 7). Plasma alanine aminotransferase activities as index of parenchymal cell injury did not change up to 5 h posttreatment (basal value 35 +/- 5 U/l) but increased to 1,950 +/- 460 U/l at 9 h. The formation of glutathione disulfide (GSSG) in plasma as an index of an extracellular oxidant stress also increased only at 9 h. Pretreatment of animals with monoclonal antibodies against the CD11b and CD18 subunits of the CD11/CD18 integrin family on the surface of the PMN reduced the number of PMNs in the liver by 50% and significantly attenuated liver injury and GSSG formation. An anti-CD11a and a nonbinding control antibody were ineffective. It is concluded that PMNs are actively involved in the pathogenesis of galactosamine and endotoxin shock and that at least in part the accumulation of PMNs, the subsequent oxidant stress, and the tissue injury in this model of experimental hepatitis are CD11b/CD18 (Mac-1) dependent.

scholarly journals MiR-144-3p Aggravated Cartilage Injury in Rheumatoid Arthritis by Regulating BMP2/PI3K/Akt Axis

2021 ◽  
Author(s):  
Mei-Li Mo ◽  
Jin-Mei Jiang ◽  
Xiao-Ping Long ◽  
Li-Hu Xie
Keyword(s):  
Extracellular Matrix ◽  
Cell Viability ◽  
Cell Injury ◽  
Tissue Injury ◽  
Cartilage Injury ◽  
Luciferase Assay ◽  
Tunel Staining ◽  
Western Blots

Abstract Objectives Present study aimed to illustrate the role of miR-144-3p in RA. Methods N1511 chondrocytes were stimulated by IL-1β to mimic RA injury model in vitro. Rats were subjected to injection of type II collagen to establish an in vivo RA model and the arthritis index score was calculated. Cell viability was determined by CCK-8. The expression of cartilage extracellular matrix proteins (Collagen II and Aggrecan) and matrix metalloproteinases protein (MMP-13) were determined by qRT-PCR and western blots. Cell apoptosis was measured by Flow cytometry. ELISA was applied to test the secretion of pro-inflammatory cytokines (IL-1β and TNF-α). Tissue injury and apoptosis were detected by HE staining and TUNEL staining. Interaction of miR-144-3p and BMP2 was verified by dual luciferase assay. Results MiR-144-3p was dramatically increased in IL-1β induced N1511 cells. MiR-144-3p depletion elevated cell viability, suppressed apoptosis, pro-inflammatory cytokine releasing, and extracellular matrix loss in IL-1β induced N1511 cells. Moreover, miR-144-3p targeted BMP2 to modulate its expression negatively. Activation of PI3K/Akt signaling compromised inhibition of BMP2 induced aggravated N1511 cell injury with IL-1β stimulation. Inhibition of miR-144-3p alleviated cartilage injury and inflammatory in RA rats. Conclusion Collectively, miR-144-3p could aggravate chondrocytes injury inflammatory response in RA via BMP2/PI3K/Akt axis.

Reduced arachidonate metabolism in ATP-depleted myocardial cells occurs early in cell injury

1990 ◽  
Vol 259 (2) ◽  
pp. H582-H591 ◽  
Author(s):  
G. E. Revtyak ◽  
L. M. Buja ◽  
K. R. Chien ◽  
W. B. Campbell
Keyword(s):  
Arachidonic Acid ◽  
Acid Metabolism ◽  
Cell Injury ◽  
Arachidonic Acid Metabolism ◽  
Atp Depletion ◽  
Neonatal Rat ◽  
Eicosatetraenoic Acid ◽  
Metabolic Inhibitors ◽  
Early Event ◽  
Myocardial Cells

Exposure of cultured neonatal rat myocardial cells to metabolic inhibitors results in cellular ATP depletion. If prolonged, arachidonic acid is released from membrane phospholipid and irreversible cell injury may ensue. The present study was undertaken to identify the major products of arachidonic acid formed when myocardial cells are depleted of ATP by the metabolic inhibitors 2-deoxy-D-glucose (2-DG) and oligomycin (OG). Under basal conditions, myocardial cells metabolize [3H]arachidonic acid to 6-keto-[3H]prostaglandin (PG)F1 alpha, [3H]PGE2, [3H]PGF2 alpha, 12-[3H]hydroxy-6,8,11,14-eicosatetraenoic acid (12-[3H]HETE) and 11-[3H]HETE, indicating that these cells contain both cyclooxygenase and lipoxygenase pathways. After exposure of myocardial cells to 10 mM 2-DG and 0.1 micrograms/ml OG for 4 h, the basal release of 6-keto-PGF1 alpha and PGE2 is reduced by 3.4-fold and 2-fold, respectively. Supernatants obtained from cells prelabeled with [3H]arachidonic acid and treated with 2-DG and OG for 4 or 12 h did not contain detectable [3H]prostaglandins or [3H]HETEs, but only [3H]arachidonic acid when compared with untreated cells. After 4 and 12 h of treatment with 2-DG and OG, there was a 3.4- and 4.4-fold net release of endogenous arachidonic acid from treated compared with untreated cells. When stimulated with bradykinin, melittin (a phospholipase activator), or arachidonic acid, the synthesis of 6-keto-PGF1 alpha increased to a similar extent in both 2-DG- and OG-treated and -untreated cells. Hence, ATP-depleted myocardial cells do not convert arachidonic acid to oxygenated metabolites under basal conditions. The reduced arachidonic acid metabolism during ATP depletion is not due to direct inactivation of cyclooxygenase or membrane phospholipase. This impairment in arachidonic acid metabolism may represent an early event in myocardial cell injury.

Selective turnover of sarcolemmal phospholipids with lethal cardiac myocyte injury

1990 ◽  
Vol 259 (2) ◽  
pp. C325-C331 ◽  
Author(s):  
Y. Miyazaki ◽  
R. W. Gross ◽  
B. E. Sobel ◽  
J. E. Saffitz
Keyword(s):  
Arachidonic Acid ◽  
Cardiac Myocytes ◽  
Cardiac Myocyte ◽  
Cell Injury ◽  
Specific Radioactivity ◽  
Ischemic Injury ◽  
Phospholipid Metabolism ◽  
Neonatal Rat ◽  
Electron Microscopic ◽  
Electron Microscopic Autoradiography

To delineate the biochemical mechanisms responsible for the transition from reversible to irreversible ischemic injury, we used quantitative electron microscopic autoradiography. Specific alterations of phospholipid catabolism in individual subcellular organelles of cardiac myocytes associated with simulated ischemic injury were identified. Neonatal rat cardiac myocytes were incubated with 5 nM [3H]arachidonic acid to label loci of phospholipid turnover and were exposed to 30 microM iodoacetate to produce reversible and irreversible injury. Although only minute amounts of arachidonic acid were incorporated into sarcolemmal phospholipids under control conditions, 20- and 96-fold increases were observed under conditions leading to reversible and irreversible cell injury, respectively. Increases of 5- and 28-fold in the specific radioactivity of sarcolemmal phospholipids in reversibly and irreversibly injured cells occurred in the absence of significant alterations in the specific radioactivity of other subcellular compartments, demonstrating that accelerated phospholipid catabolism was confined essentially to the sarcolemma. Selective catabolism of sarcolemmal phospholipids, known to be highly enriched in arachidonic acid, is likely to augment local accumulation of arachidonic acid, identified recently as a second messenger regulating myocardial K+ channels. Because the biochemical integrity of the sarcolemma is critical to both electrophysiological function and viability of myocytes, the observed selective alterations of sarcolemmal phospholipid metabolism appear to be pivotal determinants of lethal myocardial injury.

scholarly journals Mechanisms of cell injury in rat mesentery and cremaster muscle

1998 ◽  
Vol 274 (3) ◽  
pp. H1009-H1015 ◽  
Author(s):  
A. G. Harris ◽  
J. J. Costa ◽  
F. A. Delano ◽  
B. W. Zweifach ◽  
G. W. Schmid-Schönbein
Keyword(s):  
Mast Cell ◽  
Cell Injury ◽  
Tissue Injury ◽  
Platelet Activating Factor ◽  
Random Order ◽  
Mast Cell Degranulation ◽  
Cremaster Muscle ◽  
Time Points ◽  
Rat Mesentery ◽  
Dichlorofluorescin Diacetate

The events responsible for cell injury after a tissue stimulation are only incompletely understood. The purpose of this study was to examine mechanisms of cell injury in two tissues, rat mesentery and cremaster muscle, after tissue stimulation with N-formylmethionyl-leucyl-phenylalanine (FMLP) and platelet-activating factor (PAF). The response was studied in the same animal in random order using normal and leukopenic rats. The tissues were exteriorized after pentobarbital anesthesia. Five to six vascularized areas were chosen in each tissue, and cell injury and hydroperoxide production were assessed visually by continuous superfusion with 1 μM propidium iodide and 5 μM dichlorofluorescin diacetate (DCFH), respectively. FMLP (1 × 10−8M) and then PAF (1 × 10−8M) were added to the superfusate, and measurements were made at several time points. The second tissue was then examined using the same protocol. In the cremaster, there was little hydroperoxide production, and the tissue injury was eliminated after leukopenia. Leukopenia had no effect on tissue injury in the mesentery. Although hydroperoxide production was observed, there was no correlation between it and the tissue injury. The level of preactivation showed no correlation with either tissue injury or hydroperoxide production. In light of these results, mast cell degranulation may be an important mechanism of tissue injury in the mesentery.

scholarly journals Purification of a 100 kDa phospholipase A2 from spleen, lung and kidney: antiserum raised to pig spleen phospholipase A2 recognizes a similar form in bovine lung, kidney and platelets, and immunoprecipitates phospholipase A2 activity

1993 ◽  
Vol 294 (1) ◽  
pp. 261-270 ◽  
Author(s):  
D K Kim ◽  
J V Bonventre
Keyword(s):  
Arachidonic Acid ◽  
Phospholipase A2 ◽  
Large Scale ◽  
Biochemical Characterization ◽  
Tissue Injury ◽  
Rat Kidney ◽  
Deae Cellulose ◽  
Pla2 Activity ◽  
Purification Scheme ◽  
Pla2 Enzyme

Phospholipase A2 (PLA2) plays a key role in the production of intracellular and extracellular chemical mediators such as arachidonic acid, eicosanoids and platelet-activating factor, which modulate membrane channel activity, signal transduction, are vasoactive and chemotactic, and are implicated in many pathophysiological mechanisms of inflammation and tissue injury. We previously identified, purified and characterized an arachidonic acid-selective cytosolic 100-110 kDa PLA2 from bovine platelets and rat kidney that is activated during cell stimulation. The purification schemes previously published resulted in low yields of enzyme, insufficient for extensive biochemical characterization. We report the purification of a large-molecular-mass (100 kDa) PLA2 from pig spleen, bovine kidney and bovine lung, using a novel large-scale purification scheme. The enzyme was purified to near homogeneity from an acidified extract obtained from 4.8 kg of pig spleen by sequential use of DEAE-cellulose anionic exchange, Butyl-Toyopearl hydrophobic chromatography and DEAE-5PW h.p.l.c., and further purified by non-denaturing PAGE. This purification scheme will permit the preparation of quantities of purified native enzyme sufficient to study its properties and regulation. To generate antiserum against the PLA2 enzyme, the 100 kDa protein was excised and electroeluted from SDS/PAGE gels of the active fractions after DEAE-5PW h.p.l.c., and this was used as antigen. This polyclonal antibody against pig spleen 100 kDa PLA2 protein reacted with 100 kDa bands in preparations partially purified from bovine platelets, kidney and lung as well as pig spleen, and immunoprecipitated PLA2 activity from these sources. The antibody also immunoprecipitated a 100 kDa protein from cytosolic fractions of cultured renal mesangial cells, human erythroleukaemia cells and human monocytic U937 cells. Considerable PLA2 activity was present in the immunoprecipitates. To our knowledge this antibody is unique in its ability to permit measurement of PLA2 activity in the immunoprecipitate itself, and will be a useful tool for the study of the regulation and the activation mechanisms of the native PLA2 enzyme.

scholarly journals Academic-industry partnerships in addressing nutrition – [Infection-immunity-inflammation] interactions

2007 ◽  
Vol 98 (S1) ◽  
pp. S17-S23 ◽  
Author(s):  
Ricardo Uauy
Keyword(s):  
Cell Injury ◽  
Tissue Injury ◽  
Infectious Agent ◽  
Nutritional Supplement ◽  
Novel Foods ◽  
Protein Energy ◽  
Toxic Damage ◽  
Inflammatory Processes ◽  
The Impact

The interaction between nutrition and infection is a key determinant of human health. Traditionally the interaction has centered on the role of nutrients in defining host defenses and the impact of infection in defining nutritional needs and status. Over the past decades the interaction has expanded its scope to encompass the role of specific nutrients in defining acquired immune function, in the modulation of inflammatory processes and on the virulence of the infectious agent itself. More recently the role of micronutrients and fatty acids on the response of cells and tissues to hypoxic and toxic damage has been recognized suggesting a fourth dimension to the interaction. The list of nutrients affecting infection, immunity, inflammation and cell injury has expanded from traditional protein-energy supply to several vitamins, multiple minerals and more recently specific lipid components of the diet. The promise of nutrition in the defense against infection, inflammation and tissue injury has spawned a thriving pharma-nutritional supplement industry and the development of novel foods that require appropriate evaluation of efficacy, safety and effectiveness relative to costs. Academics need to aware of the ethics and the pitfalls in the interaction with industry; conversely industry has to define its role in the process of bringing new knowledge to useful products. The process needs to be interactive, transparent and clearly place public interest above all other considerations.

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