Bianca Zychar - Academia.edu (original) (raw)

Papers by Bianca Zychar

Frontiers in Pharmacology

Introduction: Alzheimer’s disease (AD) is the main type of dementia, caused by the accumulation o... more Introduction: Alzheimer’s disease (AD) is the main type of dementia, caused by the accumulation of amyloid plaques, formed by amyloid peptides after being processed from amyloid precursor protein (APP) by γ- and ß-secretases (BACE-1). Although amyloid peptides have been well established for AD, they have been found in other neurodegenerative diseases, such as Parkinson’s disease, Lewy body dementia, and amyotrophic lateral sclerosis. Inhibitors of BACE-1 have been searched and developed, but clinical trials failed due to lack of efficacy or toxicity. Nevertheless, it is still considered a good therapeutic target, as it was proven to remove amyloid peptides and improve memory.Methods: In this work, we designed a peptide based on a sequence obtained from the marine fish Merluccius productus and evaluated it by molecular docking to verify its binding to BACE-1, which was tested experimentally by enzymatic kinetics and cell culture assays. The peptide was injected in healthy mice to stu...

Small RNAs (sRNA) and microRNAs (miRNAs) are small endogenous noncoding single-stranded RNAs that... more Small RNAs (sRNA) and microRNAs (miRNAs) are small endogenous noncoding single-stranded RNAs that regulate gene expression in eukaryotes. Experiments in mice and humans have revealed that a typical small RNA can affect the expression of a wide range of genes, implying that small RNAs function as global regulators. Here, we used small RNA deep sequencing to investigate at how jararhagin, a metalloproteinase toxin produced from the venom of Bothrops jararaca, affected mmu-miRs expression in mice 2 h and 24 h after injection. The findings revealed that seven mmu-miRs were substantially differentially expressed (p-value (p (Corr) cut-off 0.05, FC 2) at 2h after jararhagin exposure, and that the majority of them were upregulated when compared to PBS. In contrast to these findings, a comparison of Jar 24h vs PBS 24hrs demonstrated that the majority of identified mmu-miRs were downregulated. Furthermore, the studies demonstrated that mmu-miR can target the expression of several genes invol...

Toxins, 2021

Snake venom metalloproteinases (SVMP) are involved in local inflammatory reactions observed after... more Snake venom metalloproteinases (SVMP) are involved in local inflammatory reactions observed after snakebites. Based on domain composition, they are classified as PI (pro-domain + proteolytic domain), PII (PI + disintegrin-like domains), or PIII (PII + cysteine-rich domains). Here, we studied the role of different SVMPs domains in inducing the expression of adhesion molecules at the microcirculation of the cremaster muscle of mice. We used Jararhagin (Jar)—a PIII SVMP with intense hemorrhagic activity, and Jar-C—a Jar devoid of the catalytic domain, with no hemorrhagic activity, both isolated from B. jararaca venom and BnP-1—a weakly hemorrhagic P1 SVMP from B. neuwiedi venom. Toxins (0.5 µg) or PBS (100 µL) were injected into the scrotum of mice, and 2, 4, or 24 h later, the protein and gene expression of CD54 and CD31 in the endothelium, and integrins (CD11a and CD11b), expressed in leukocytes were evaluated. Toxins induced significant increases in CD54, CD11a, and CD11b at the ini...

Biochemical and Biophysical Research Communications, 2019

Snake venom metalloproteinases (SVMPs) are key toxins involved in local inflammatory reactions af... more Snake venom metalloproteinases (SVMPs) are key toxins involved in local inflammatory reactions after snakebites. This study aimed to investigate the effect of SVMP domains on the alterations in leukocyteendothelium interactions in the microcirculation of mouse cremaster muscle. We studied three toxins: BnP1, a PI-toxin isolated from Bothrops neuwiedi venom, which only bears a catalytic domain; Jararhagin (Jar), a PIII-toxin isolated from Bothrops jararaca venom with a catalytic domain, as well as ECDdisintegrin and cysteine-rich domains; and Jar-C, which is produced from the autolysis of Jar and devoid of a catalytic domain. All these toxins induced an increase in the adhesion and migration of leukocytes. By inhibiting the catalytic activity of Jar and BnP1 with 1.10-phenanthroline (oPhe), leukocytes were no longer recruited. Circular dichroism analysis showed structural changes in oPhe-treated Jar, but these changes were not enough to prevent the binding of Jar to collagen, which occurred through the ECD-disintegrin domain. The results showed that the catalytic domain of SVMPs is the principal domain responsible for the induction of leukocyte recruitment and suggest that the other domains could also present inflammatory potential only when devoid of the catalytic domain, as with Jar-C.

The journal of venomous animals and toxins including tropical diseases, 2017

Sea urchins are animals commonly found on the Brazilian shoreline, being Echinometra lucunter the... more Sea urchins are animals commonly found on the Brazilian shoreline, being Echinometra lucunter the most abundant species. Accidents caused by E. lucunter have been reported as one of the most frequent in Brazil, and are characterized by intense pain and inflammation, consequence of spine puncture in the skin. In order to characterize such toxic effects, we isolated one molecule that caused inflammatory and nociceptive effects. E. lucunter specimens were collected without gender distinction. Spines were removed and molecules were extracted, fractionated by RP-HPLC and assayed for inflammatory and nociceptive activity, in a biological-driven fractionation way, until the obtainment of one active molecule and its subsequent analysis by mass spectrometry (MS and MS/MS). For inflammation, intravital microscopy was performed on the mouse cremaster muscle, in order to evaluate rolled, adherent and migrating leukocytes. Paw edema was also evaluated. For the nociceptive activity, the paw press...

Toxicon : official journal of the International Society on Toxinology, 2010

In the present study, it was investigated which components are responsible for the anti-inflammat... more In the present study, it was investigated which components are responsible for the anti-inflammatory properties of Crotalus durissus terrificus venom (CdtV). The effect of crotoxin, as well as of other CdtV components was evaluated on edema, cell migration and alterations in leukocyte-endothelium interactions induced by carrageenan. Crotoxin (40 microg kg(-1)) was injected at different time periods before or after the injection of carrageenan (15 mg kg(-1)) into the mouse hind paw, peritoneum or scrotum. Results showed that crotoxin, but not other CdtV components, significantly inhibited inflammatory edema and cell migration when administered before or after carrageenan injection in mice. This toxin also prevented the occurrence of alterations in leukocyte-endothelium interactions induced by carrageenan injection, such as the increase in adhered cells. In animals pretreated with Boc2 (a selective antagonist of formyl peptide receptors), crotoxin showed neither inhibitory effects on ...

Toxicon, 2010

Various toxins isolated from Bothrops snake venoms induce inflammatory reactions and have been cl... more Various toxins isolated from Bothrops snake venoms induce inflammatory reactions and have been claimed to contribute to the severity of local symptoms present in this envenomation. Notwithstanding, the relative participation of serine proteases, metalloproteases and phospholipases A 2 in the inflammatory reaction produced by crude Bothrops venoms is poorly understood. Herein, crude Bothrops jararaca venom was treated with phenylmethanesulfonyl fluoride (PMSF), 1,10-phenanthroline (oPhe), or p-bromophenacyl-bromide (p-BPB) to inhibit those classes of enzymes, respectively, and inflammatory parameters were evaluated and compared to those induced by the control crude venom. The intensity of edema and hyperalgesia/allodynia was remarkably reduced in animals administered with oPhe-treated venom. Leukocyte-endothelium interactions (LEI), such as adhesion and migration of leukocytes, were also modified at 2 h and 24 h. Edema and LEI parameters induced by p-BPB-treated venom were similar to those observed with the control venom, but hyperalgesia/allodynia was significantly lower. Inflammatory parameters induced by PMSF-treated venom were similar to those induced by the crude venom, except for a mild reduction in edema intensity. Our results indicate that metalloproteases have a pivotal role in the inflammatory reactions induced by B. jararaca venom, and phospholipases A 2 and serine proteases have a minor role.

Toxicon, 2008

Crotoxin is the main neurotoxic component of Crotalus durissus terrificus snake venom and modulat... more Crotoxin is the main neurotoxic component of Crotalus durissus terrificus snake venom and modulates immune and inflammatory responses, interfering with the activity of leukocytes. In the present work, the effects of crotoxin on the number of blood and lymphatic leukocytes and on lymph nodes and spleen lymphocytes population were investigated. The toxin s.c. administered to male Wistar rats, decreases the number of lymphocytes in blood and lymph circulation and increases the content of B and Tlymphocytes in lymph nodes. These effects were detected 1-2 h after treatment. The crotoxin molecule is composed of two subunits, an acidic non-toxic polypeptide, named crotapotin and a toxic basic phospholipase A 2 (PLA 2). PLA 2 , but not crotapotin, decreased the number of circulating blood and lymph lymphocytes. Crotoxin promotes leukocyte adherence to endothelial cells of blood microcirculation and to lymph node high endothelial venules, which might contribute to the drop in the number of circulating lymphocytes. Crotoxin increases expression of the adhesion molecule LFA-1 in lymphocytes. The changes in the expression of the adhesion molecule might contribute, at least in part, for the increased leukocyte adhesion to endothelium. Zileuton, a 5lipoxygenase inhibitor, blocked the decrease in the number of circulating leukocytes induced by crotoxin and also abolished the changes observed in leukocyte-endothelial interactions, suggesting the involvement of lipoxygenase-derived mediators in the effects of the toxin.

Toxicon, 2008

The effect of Bothrops antivenom on blocking the disturbances induced by Bothrops jararaca venom ... more The effect of Bothrops antivenom on blocking the disturbances induced by Bothrops jararaca venom in leukocyte-endothelial interactions (LEI) at the microcirculation of the cremaster muscle in mice was evaluated using intravital microscopy. Our findings showed that an i.v. injection of Bothrops antivenom, per se, induced changes in LEI, similar to those induced by an s.c. injection of B. jararaca venom, and that Bothrops antivenom can also induce ephemeral symptoms, such as tremor and dyspnea in mice. These effects were mostly due to phenol used in Bothrops antivenom as a preservative, since animals injected i.v. with a phenol solution, but not with phenol-free Bothrops antivenom, presented those effects on LEI, and also tremor and dyspnea. In addition, phenol-free antivenom abrogated venom-induced changes in LEI parameters. The present data demonstrate that Bothrops antivenom contains antibodies that neutralize toxins of B. jararaca venom that impair LEI, and suggest that the phenol used as a preservative in it can originate some undesired effects.

Experimental Biology and Medicine, 2011

Patagonfibrase is a P-III class metalloproteinase isolated from the venom of Philodryas patagonie... more Patagonfibrase is a P-III class metalloproteinase isolated from the venom of Philodryas patagoniensis, a South-American, rear-fanged ‘colubrid’ snake responsible for accidents with clinical significance. Since local inflammatory reactions are conspicuous signs of snakebites inflicted by this species and taking into consideration that most snake venom metalloproteinases exhibit inflammatory activity, this study deals with the proinflammatory effects evoked by patagonfibrase. Herein, we demonstrate that patagonfibrase causes a time- and dose-dependent hemorrhagic edema when injected into mouse hind paws. The peak of edema occurred at 30 min after injection, and the minimum edematogenic dose was 0.021 μg. By histological analysis, the presence of moderate to marked edema and hemorrhage, and a mild inflammatory infiltrate was observed. When injected subcutaneously into the scrotal bag of mice, patagonfibrase induced cell recruitment with a significant alteration in physiological paramet...

Experimental Biology and Medicine, 2011

The sea urchin, Echinometra lucunter, can be found along the Western Central Atlantic shores. In ... more The sea urchin, Echinometra lucunter, can be found along the Western Central Atlantic shores. In Brazil, it is responsible by circa 50% of the accidents caused by marine animals. The symptoms usually surpass trauma and may be pathologically varied and last differently, ranging from spontaneous healing in a few days, to painful consequences lasting for weeks. In this work, we have mimicked the sea urchin accident by administering an aqueous extract of the spine into mice and rats and evaluated the pathophysiological developments. Our data clearly indicate that the sea urchin accident is indeed a pro-inflammatory event, triggered by toxins present in the spine that can cause edema and alteration in the leukocyte–endothelial interaction. Moreover, the spine extract was shown to exhibit a hyperalgesic effect. The extract is rich in proteins, as observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, but also contains other molecules that can be analyzed by reversed phase ...

Peptides, 2014

Echinometra lucunter is an abundant sea urchin found in Brazilian waters. Accidents caused by thi... more Echinometra lucunter is an abundant sea urchin found in Brazilian waters. Accidents caused by this animal are common and are characterized by the penetration of the spines in the skin, which raises an inflammatory reaction through mechanical trauma as well as by the presumable action of toxins. Additionally, there have been reports of inflammatory reaction after the consumption of raw sea urchin eggs. In this work, we have isolated a peptide from E. lucunter coelomic fluid that could elicit inflammatory reactions, such as paw edema, leukocyte recruitment and diminishment of the pain threshold. This peptide was termed Echinometrin. Moreover, the peptide administration was able to produce in vivo degranulation of mouse mast cells, in a dose-response manner. The peptide was 'de novo' sequenced by mass spectrometry and its synthetic analog could reproduce all the observed effects. Sequence alignment indicates that this peptide is comprised in vitellogenin, an abundant nutrient protein present in the gametogenic cells of sea urchins, making it possible that echinometrin would be a cryptide with pro-inflammatory effects.

Frontiers in Pharmacology

Introduction: Alzheimer’s disease (AD) is the main type of dementia, caused by the accumulation o... more Introduction: Alzheimer’s disease (AD) is the main type of dementia, caused by the accumulation of amyloid plaques, formed by amyloid peptides after being processed from amyloid precursor protein (APP) by γ- and ß-secretases (BACE-1). Although amyloid peptides have been well established for AD, they have been found in other neurodegenerative diseases, such as Parkinson’s disease, Lewy body dementia, and amyotrophic lateral sclerosis. Inhibitors of BACE-1 have been searched and developed, but clinical trials failed due to lack of efficacy or toxicity. Nevertheless, it is still considered a good therapeutic target, as it was proven to remove amyloid peptides and improve memory.Methods: In this work, we designed a peptide based on a sequence obtained from the marine fish Merluccius productus and evaluated it by molecular docking to verify its binding to BACE-1, which was tested experimentally by enzymatic kinetics and cell culture assays. The peptide was injected in healthy mice to stu...

Biochemical and Biophysical Research Communications

Snake venom metalloproteinases (SVMPs) are key toxins involved in local inflammatory reactions af... more Snake venom metalloproteinases (SVMPs) are key toxins involved in local inflammatory reactions after snakebites. This study aimed to investigate the effect of SVMP domains on the alterations in leukocyte-endothelium interactions in the microcirculation of mouse cremaster muscle. We studied three toxins: BnP1, a PI-toxin isolated from Bothrops neuwiedi venom, which only bears a catalytic domain; Jararhagin (Jar), a PIII-toxin isolated from Bothrops jararaca venom with a catalytic domain, as well as ECD-disintegrin and cysteine-rich domains; and Jar-C, which is produced from the autolysis of Jar and devoid of a catalytic domain. All these toxins induced an increase in the adhesion and migration of leukocytes. By inhibiting the catalytic activity of Jar and BnP1 with 1.10-phenanthroline (oPhe), leukocytes were no longer recruited. Circular dichroism analysis showed structural changes in oPhe-treated Jar, but these changes were not enough to prevent the binding of Jar to collagen, which occurred through the ECD-disintegrin domain. The results showed that the catalytic domain of SVMPs is the principal domain responsible for the induction of leukocyte recruitment and suggest that the other domains could also present inflammatory potential only when devoid of the catalytic domain, as with Jar-C.

Toxicon : official journal of the International Society on Toxinology, 2010

In the present study, it was investigated which components are responsible for the anti-inflammat... more In the present study, it was investigated which components are responsible for the anti-inflammatory properties of Crotalus durissus terrificus venom (CdtV). The effect of crotoxin, as well as of other CdtV components was evaluated on edema, cell migration and alterations in leukocyte-endothelium interactions induced by carrageenan. Crotoxin (40 microg kg(-1)) was injected at different time periods before or after the injection of carrageenan (15 mg kg(-1)) into the mouse hind paw, peritoneum or scrotum. Results showed that crotoxin, but not other CdtV components, significantly inhibited inflammatory edema and cell migration when administered before or after carrageenan injection in mice. This toxin also prevented the occurrence of alterations in leukocyte-endothelium interactions induced by carrageenan injection, such as the increase in adhered cells. In animals pretreated with Boc2 (a selective antagonist of formyl peptide receptors), crotoxin showed neither inhibitory effects on ...

Experimental Biology and Medicine, 2011

The sea urchin, Echinometra lucunter, can be found along the Western Central Atlantic shores. In ... more The sea urchin, Echinometra lucunter, can be found along the Western Central Atlantic shores. In Brazil, it is responsible by circa 50% of the accidents caused by marine animals. The symptoms usually surpass trauma and may be pathologically varied and last differently, ranging from spontaneous healing in a few days, to painful consequences lasting for weeks. In this work, we have mimicked the sea urchin accident by administering an aqueous extract of the spine into mice and rats and evaluated the pathophysiological developments. Our data clearly indicate that the sea urchin accident is indeed a pro-inflammatory event, triggered by toxins present in the spine that can cause edema and alteration in the leukocyte–endothelial interaction. Moreover, the spine extract was shown to exhibit a hyperalgesic effect. The extract is rich in proteins, as observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, but also contains other molecules that can be analyzed by reversed phase ...

Toxicon, 2008

The effect of Bothrops antivenom on blocking the disturbances induced by Bothrops jararaca venom ... more The effect of Bothrops antivenom on blocking the disturbances induced by Bothrops jararaca venom in leukocyte-endothelial interactions (LEI) at the microcirculation of the cremaster muscle in mice was evaluated using intravital microscopy. Our findings showed that an i.v. injection of Bothrops antivenom, per se, induced changes in LEI, similar to those induced by an s.c. injection of B. jararaca venom, and that Bothrops antivenom can also induce ephemeral symptoms, such as tremor and dyspnea in mice. These effects were mostly due to phenol used in Bothrops antivenom as a preservative, since animals injected i.v. with a phenol solution, but not with phenol-free Bothrops antivenom, presented those effects on LEI, and also tremor and dyspnea. In addition, phenol-free antivenom abrogated venom-induced changes in LEI parameters. The present data demonstrate that Bothrops antivenom contains antibodies that neutralize toxins of B. jararaca venom that impair LEI, and suggest that the phenol used as a preservative in it can originate some undesired effects.

Frontiers in Pharmacology

Introduction: Alzheimer’s disease (AD) is the main type of dementia, caused by the accumulation o... more Introduction: Alzheimer’s disease (AD) is the main type of dementia, caused by the accumulation of amyloid plaques, formed by amyloid peptides after being processed from amyloid precursor protein (APP) by γ- and ß-secretases (BACE-1). Although amyloid peptides have been well established for AD, they have been found in other neurodegenerative diseases, such as Parkinson’s disease, Lewy body dementia, and amyotrophic lateral sclerosis. Inhibitors of BACE-1 have been searched and developed, but clinical trials failed due to lack of efficacy or toxicity. Nevertheless, it is still considered a good therapeutic target, as it was proven to remove amyloid peptides and improve memory.Methods: In this work, we designed a peptide based on a sequence obtained from the marine fish Merluccius productus and evaluated it by molecular docking to verify its binding to BACE-1, which was tested experimentally by enzymatic kinetics and cell culture assays. The peptide was injected in healthy mice to stu...

Small RNAs (sRNA) and microRNAs (miRNAs) are small endogenous noncoding single-stranded RNAs that... more Small RNAs (sRNA) and microRNAs (miRNAs) are small endogenous noncoding single-stranded RNAs that regulate gene expression in eukaryotes. Experiments in mice and humans have revealed that a typical small RNA can affect the expression of a wide range of genes, implying that small RNAs function as global regulators. Here, we used small RNA deep sequencing to investigate at how jararhagin, a metalloproteinase toxin produced from the venom of Bothrops jararaca, affected mmu-miRs expression in mice 2 h and 24 h after injection. The findings revealed that seven mmu-miRs were substantially differentially expressed (p-value (p (Corr) cut-off 0.05, FC 2) at 2h after jararhagin exposure, and that the majority of them were upregulated when compared to PBS. In contrast to these findings, a comparison of Jar 24h vs PBS 24hrs demonstrated that the majority of identified mmu-miRs were downregulated. Furthermore, the studies demonstrated that mmu-miR can target the expression of several genes invol...

Toxins, 2021

Snake venom metalloproteinases (SVMP) are involved in local inflammatory reactions observed after... more Snake venom metalloproteinases (SVMP) are involved in local inflammatory reactions observed after snakebites. Based on domain composition, they are classified as PI (pro-domain + proteolytic domain), PII (PI + disintegrin-like domains), or PIII (PII + cysteine-rich domains). Here, we studied the role of different SVMPs domains in inducing the expression of adhesion molecules at the microcirculation of the cremaster muscle of mice. We used Jararhagin (Jar)—a PIII SVMP with intense hemorrhagic activity, and Jar-C—a Jar devoid of the catalytic domain, with no hemorrhagic activity, both isolated from B. jararaca venom and BnP-1—a weakly hemorrhagic P1 SVMP from B. neuwiedi venom. Toxins (0.5 µg) or PBS (100 µL) were injected into the scrotum of mice, and 2, 4, or 24 h later, the protein and gene expression of CD54 and CD31 in the endothelium, and integrins (CD11a and CD11b), expressed in leukocytes were evaluated. Toxins induced significant increases in CD54, CD11a, and CD11b at the ini...

Biochemical and Biophysical Research Communications, 2019

Snake venom metalloproteinases (SVMPs) are key toxins involved in local inflammatory reactions af... more Snake venom metalloproteinases (SVMPs) are key toxins involved in local inflammatory reactions after snakebites. This study aimed to investigate the effect of SVMP domains on the alterations in leukocyteendothelium interactions in the microcirculation of mouse cremaster muscle. We studied three toxins: BnP1, a PI-toxin isolated from Bothrops neuwiedi venom, which only bears a catalytic domain; Jararhagin (Jar), a PIII-toxin isolated from Bothrops jararaca venom with a catalytic domain, as well as ECDdisintegrin and cysteine-rich domains; and Jar-C, which is produced from the autolysis of Jar and devoid of a catalytic domain. All these toxins induced an increase in the adhesion and migration of leukocytes. By inhibiting the catalytic activity of Jar and BnP1 with 1.10-phenanthroline (oPhe), leukocytes were no longer recruited. Circular dichroism analysis showed structural changes in oPhe-treated Jar, but these changes were not enough to prevent the binding of Jar to collagen, which occurred through the ECD-disintegrin domain. The results showed that the catalytic domain of SVMPs is the principal domain responsible for the induction of leukocyte recruitment and suggest that the other domains could also present inflammatory potential only when devoid of the catalytic domain, as with Jar-C.

The journal of venomous animals and toxins including tropical diseases, 2017

Sea urchins are animals commonly found on the Brazilian shoreline, being Echinometra lucunter the... more Sea urchins are animals commonly found on the Brazilian shoreline, being Echinometra lucunter the most abundant species. Accidents caused by E. lucunter have been reported as one of the most frequent in Brazil, and are characterized by intense pain and inflammation, consequence of spine puncture in the skin. In order to characterize such toxic effects, we isolated one molecule that caused inflammatory and nociceptive effects. E. lucunter specimens were collected without gender distinction. Spines were removed and molecules were extracted, fractionated by RP-HPLC and assayed for inflammatory and nociceptive activity, in a biological-driven fractionation way, until the obtainment of one active molecule and its subsequent analysis by mass spectrometry (MS and MS/MS). For inflammation, intravital microscopy was performed on the mouse cremaster muscle, in order to evaluate rolled, adherent and migrating leukocytes. Paw edema was also evaluated. For the nociceptive activity, the paw press...

Toxicon : official journal of the International Society on Toxinology, 2010

In the present study, it was investigated which components are responsible for the anti-inflammat... more In the present study, it was investigated which components are responsible for the anti-inflammatory properties of Crotalus durissus terrificus venom (CdtV). The effect of crotoxin, as well as of other CdtV components was evaluated on edema, cell migration and alterations in leukocyte-endothelium interactions induced by carrageenan. Crotoxin (40 microg kg(-1)) was injected at different time periods before or after the injection of carrageenan (15 mg kg(-1)) into the mouse hind paw, peritoneum or scrotum. Results showed that crotoxin, but not other CdtV components, significantly inhibited inflammatory edema and cell migration when administered before or after carrageenan injection in mice. This toxin also prevented the occurrence of alterations in leukocyte-endothelium interactions induced by carrageenan injection, such as the increase in adhered cells. In animals pretreated with Boc2 (a selective antagonist of formyl peptide receptors), crotoxin showed neither inhibitory effects on ...

Toxicon, 2010

Various toxins isolated from Bothrops snake venoms induce inflammatory reactions and have been cl... more Various toxins isolated from Bothrops snake venoms induce inflammatory reactions and have been claimed to contribute to the severity of local symptoms present in this envenomation. Notwithstanding, the relative participation of serine proteases, metalloproteases and phospholipases A 2 in the inflammatory reaction produced by crude Bothrops venoms is poorly understood. Herein, crude Bothrops jararaca venom was treated with phenylmethanesulfonyl fluoride (PMSF), 1,10-phenanthroline (oPhe), or p-bromophenacyl-bromide (p-BPB) to inhibit those classes of enzymes, respectively, and inflammatory parameters were evaluated and compared to those induced by the control crude venom. The intensity of edema and hyperalgesia/allodynia was remarkably reduced in animals administered with oPhe-treated venom. Leukocyte-endothelium interactions (LEI), such as adhesion and migration of leukocytes, were also modified at 2 h and 24 h. Edema and LEI parameters induced by p-BPB-treated venom were similar to those observed with the control venom, but hyperalgesia/allodynia was significantly lower. Inflammatory parameters induced by PMSF-treated venom were similar to those induced by the crude venom, except for a mild reduction in edema intensity. Our results indicate that metalloproteases have a pivotal role in the inflammatory reactions induced by B. jararaca venom, and phospholipases A 2 and serine proteases have a minor role.

Toxicon, 2008

Crotoxin is the main neurotoxic component of Crotalus durissus terrificus snake venom and modulat... more Crotoxin is the main neurotoxic component of Crotalus durissus terrificus snake venom and modulates immune and inflammatory responses, interfering with the activity of leukocytes. In the present work, the effects of crotoxin on the number of blood and lymphatic leukocytes and on lymph nodes and spleen lymphocytes population were investigated. The toxin s.c. administered to male Wistar rats, decreases the number of lymphocytes in blood and lymph circulation and increases the content of B and Tlymphocytes in lymph nodes. These effects were detected 1-2 h after treatment. The crotoxin molecule is composed of two subunits, an acidic non-toxic polypeptide, named crotapotin and a toxic basic phospholipase A 2 (PLA 2). PLA 2 , but not crotapotin, decreased the number of circulating blood and lymph lymphocytes. Crotoxin promotes leukocyte adherence to endothelial cells of blood microcirculation and to lymph node high endothelial venules, which might contribute to the drop in the number of circulating lymphocytes. Crotoxin increases expression of the adhesion molecule LFA-1 in lymphocytes. The changes in the expression of the adhesion molecule might contribute, at least in part, for the increased leukocyte adhesion to endothelium. Zileuton, a 5lipoxygenase inhibitor, blocked the decrease in the number of circulating leukocytes induced by crotoxin and also abolished the changes observed in leukocyte-endothelial interactions, suggesting the involvement of lipoxygenase-derived mediators in the effects of the toxin.

Toxicon, 2008

The effect of Bothrops antivenom on blocking the disturbances induced by Bothrops jararaca venom ... more The effect of Bothrops antivenom on blocking the disturbances induced by Bothrops jararaca venom in leukocyte-endothelial interactions (LEI) at the microcirculation of the cremaster muscle in mice was evaluated using intravital microscopy. Our findings showed that an i.v. injection of Bothrops antivenom, per se, induced changes in LEI, similar to those induced by an s.c. injection of B. jararaca venom, and that Bothrops antivenom can also induce ephemeral symptoms, such as tremor and dyspnea in mice. These effects were mostly due to phenol used in Bothrops antivenom as a preservative, since animals injected i.v. with a phenol solution, but not with phenol-free Bothrops antivenom, presented those effects on LEI, and also tremor and dyspnea. In addition, phenol-free antivenom abrogated venom-induced changes in LEI parameters. The present data demonstrate that Bothrops antivenom contains antibodies that neutralize toxins of B. jararaca venom that impair LEI, and suggest that the phenol used as a preservative in it can originate some undesired effects.

Experimental Biology and Medicine, 2011

Patagonfibrase is a P-III class metalloproteinase isolated from the venom of Philodryas patagonie... more Patagonfibrase is a P-III class metalloproteinase isolated from the venom of Philodryas patagoniensis, a South-American, rear-fanged ‘colubrid’ snake responsible for accidents with clinical significance. Since local inflammatory reactions are conspicuous signs of snakebites inflicted by this species and taking into consideration that most snake venom metalloproteinases exhibit inflammatory activity, this study deals with the proinflammatory effects evoked by patagonfibrase. Herein, we demonstrate that patagonfibrase causes a time- and dose-dependent hemorrhagic edema when injected into mouse hind paws. The peak of edema occurred at 30 min after injection, and the minimum edematogenic dose was 0.021 μg. By histological analysis, the presence of moderate to marked edema and hemorrhage, and a mild inflammatory infiltrate was observed. When injected subcutaneously into the scrotal bag of mice, patagonfibrase induced cell recruitment with a significant alteration in physiological paramet...

Experimental Biology and Medicine, 2011

The sea urchin, Echinometra lucunter, can be found along the Western Central Atlantic shores. In ... more The sea urchin, Echinometra lucunter, can be found along the Western Central Atlantic shores. In Brazil, it is responsible by circa 50% of the accidents caused by marine animals. The symptoms usually surpass trauma and may be pathologically varied and last differently, ranging from spontaneous healing in a few days, to painful consequences lasting for weeks. In this work, we have mimicked the sea urchin accident by administering an aqueous extract of the spine into mice and rats and evaluated the pathophysiological developments. Our data clearly indicate that the sea urchin accident is indeed a pro-inflammatory event, triggered by toxins present in the spine that can cause edema and alteration in the leukocyte–endothelial interaction. Moreover, the spine extract was shown to exhibit a hyperalgesic effect. The extract is rich in proteins, as observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, but also contains other molecules that can be analyzed by reversed phase ...

Peptides, 2014

Echinometra lucunter is an abundant sea urchin found in Brazilian waters. Accidents caused by thi... more Echinometra lucunter is an abundant sea urchin found in Brazilian waters. Accidents caused by this animal are common and are characterized by the penetration of the spines in the skin, which raises an inflammatory reaction through mechanical trauma as well as by the presumable action of toxins. Additionally, there have been reports of inflammatory reaction after the consumption of raw sea urchin eggs. In this work, we have isolated a peptide from E. lucunter coelomic fluid that could elicit inflammatory reactions, such as paw edema, leukocyte recruitment and diminishment of the pain threshold. This peptide was termed Echinometrin. Moreover, the peptide administration was able to produce in vivo degranulation of mouse mast cells, in a dose-response manner. The peptide was 'de novo' sequenced by mass spectrometry and its synthetic analog could reproduce all the observed effects. Sequence alignment indicates that this peptide is comprised in vitellogenin, an abundant nutrient protein present in the gametogenic cells of sea urchins, making it possible that echinometrin would be a cryptide with pro-inflammatory effects.

Frontiers in Pharmacology

Introduction: Alzheimer’s disease (AD) is the main type of dementia, caused by the accumulation o... more Introduction: Alzheimer’s disease (AD) is the main type of dementia, caused by the accumulation of amyloid plaques, formed by amyloid peptides after being processed from amyloid precursor protein (APP) by γ- and ß-secretases (BACE-1). Although amyloid peptides have been well established for AD, they have been found in other neurodegenerative diseases, such as Parkinson’s disease, Lewy body dementia, and amyotrophic lateral sclerosis. Inhibitors of BACE-1 have been searched and developed, but clinical trials failed due to lack of efficacy or toxicity. Nevertheless, it is still considered a good therapeutic target, as it was proven to remove amyloid peptides and improve memory.Methods: In this work, we designed a peptide based on a sequence obtained from the marine fish Merluccius productus and evaluated it by molecular docking to verify its binding to BACE-1, which was tested experimentally by enzymatic kinetics and cell culture assays. The peptide was injected in healthy mice to stu...

Biochemical and Biophysical Research Communications

Snake venom metalloproteinases (SVMPs) are key toxins involved in local inflammatory reactions af... more Snake venom metalloproteinases (SVMPs) are key toxins involved in local inflammatory reactions after snakebites. This study aimed to investigate the effect of SVMP domains on the alterations in leukocyte-endothelium interactions in the microcirculation of mouse cremaster muscle. We studied three toxins: BnP1, a PI-toxin isolated from Bothrops neuwiedi venom, which only bears a catalytic domain; Jararhagin (Jar), a PIII-toxin isolated from Bothrops jararaca venom with a catalytic domain, as well as ECD-disintegrin and cysteine-rich domains; and Jar-C, which is produced from the autolysis of Jar and devoid of a catalytic domain. All these toxins induced an increase in the adhesion and migration of leukocytes. By inhibiting the catalytic activity of Jar and BnP1 with 1.10-phenanthroline (oPhe), leukocytes were no longer recruited. Circular dichroism analysis showed structural changes in oPhe-treated Jar, but these changes were not enough to prevent the binding of Jar to collagen, which occurred through the ECD-disintegrin domain. The results showed that the catalytic domain of SVMPs is the principal domain responsible for the induction of leukocyte recruitment and suggest that the other domains could also present inflammatory potential only when devoid of the catalytic domain, as with Jar-C.

Toxicon : official journal of the International Society on Toxinology, 2010

In the present study, it was investigated which components are responsible for the anti-inflammat... more In the present study, it was investigated which components are responsible for the anti-inflammatory properties of Crotalus durissus terrificus venom (CdtV). The effect of crotoxin, as well as of other CdtV components was evaluated on edema, cell migration and alterations in leukocyte-endothelium interactions induced by carrageenan. Crotoxin (40 microg kg(-1)) was injected at different time periods before or after the injection of carrageenan (15 mg kg(-1)) into the mouse hind paw, peritoneum or scrotum. Results showed that crotoxin, but not other CdtV components, significantly inhibited inflammatory edema and cell migration when administered before or after carrageenan injection in mice. This toxin also prevented the occurrence of alterations in leukocyte-endothelium interactions induced by carrageenan injection, such as the increase in adhered cells. In animals pretreated with Boc2 (a selective antagonist of formyl peptide receptors), crotoxin showed neither inhibitory effects on ...

Experimental Biology and Medicine, 2011

The sea urchin, Echinometra lucunter, can be found along the Western Central Atlantic shores. In ... more The sea urchin, Echinometra lucunter, can be found along the Western Central Atlantic shores. In Brazil, it is responsible by circa 50% of the accidents caused by marine animals. The symptoms usually surpass trauma and may be pathologically varied and last differently, ranging from spontaneous healing in a few days, to painful consequences lasting for weeks. In this work, we have mimicked the sea urchin accident by administering an aqueous extract of the spine into mice and rats and evaluated the pathophysiological developments. Our data clearly indicate that the sea urchin accident is indeed a pro-inflammatory event, triggered by toxins present in the spine that can cause edema and alteration in the leukocyte–endothelial interaction. Moreover, the spine extract was shown to exhibit a hyperalgesic effect. The extract is rich in proteins, as observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, but also contains other molecules that can be analyzed by reversed phase ...

Toxicon, 2008

The effect of Bothrops antivenom on blocking the disturbances induced by Bothrops jararaca venom ... more The effect of Bothrops antivenom on blocking the disturbances induced by Bothrops jararaca venom in leukocyte-endothelial interactions (LEI) at the microcirculation of the cremaster muscle in mice was evaluated using intravital microscopy. Our findings showed that an i.v. injection of Bothrops antivenom, per se, induced changes in LEI, similar to those induced by an s.c. injection of B. jararaca venom, and that Bothrops antivenom can also induce ephemeral symptoms, such as tremor and dyspnea in mice. These effects were mostly due to phenol used in Bothrops antivenom as a preservative, since animals injected i.v. with a phenol solution, but not with phenol-free Bothrops antivenom, presented those effects on LEI, and also tremor and dyspnea. In addition, phenol-free antivenom abrogated venom-induced changes in LEI parameters. The present data demonstrate that Bothrops antivenom contains antibodies that neutralize toxins of B. jararaca venom that impair LEI, and suggest that the phenol used as a preservative in it can originate some undesired effects.