Made available in DSpace on 2014-12-17T14:03:25Z (GMT). No. of bitstreams: 1 AdrianaSB.pdf: 1664966 bytes, checksum: 33b28b577c6c69f20823f4e4a84e7540 (MD5) Previous issue date: 2008-06-13 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The occurrence of bioactive compounds in marine organisms comes awaking the interest of the pharmaceutical industry. Heparin, a sulfated polysaccharide which presence was already identified in several marine invertebrates, is very attractive due its remarkable functional versatility. Besides to intervene in blood coagulation, this molecule has a great anti-inflammatory potential. However, its strong anticoagulant activity difficult the clinical exploitation of its anti-inflammatory properties. Thus, the aims of this work were to evaluate the effect of a heparin-like compound (heparinoid), isolated from the cephalotorax of the Litopenaeus vannamei shrimp, on the inflammatory response, hemostasia and synthesis of antithrombotic heparan sulfate by endothelial cells, besides studying some aspects concerning its structure. The purified heparinoid was structurally characterized following an analytical boarding, involving electrophoresis and chromatography. The structural analysis have shown that this compound possess a high content of glucuronic acid residues and disulfated disaccharide units. In contrast to mammalian heparin, the heparinoid was incapable to stimulate the synthesis of heparan sulfate by endothelial cells in the tested concentrations, beyond to show reduced anticoagulant activity and hemorrhagic effect. In a model of acute inflammation, the compound isolated from the shrimp reduced more than 50% of the cellular infiltration. Besides reduce the activity of MMP-9 and proMMP-2 of the peritoneal lavage of inflamed animals, the heparinoid also reduced the activity of MMP-9 secreted by activated human leukocytes. These results demonstrate the potential of heparinoid from L. vannamei to intervene in the inflammatory response. For possessing reduced anticoagulant activity and hemorrhagic effect, this compound can serve as a structural model to direct the development of more specific therapeutical agents to the treatment of inflammatory diseases / A ocorr?ncia de compostos bioativos em representantes da biodiversidade marinha vem despertando o interesse da ind?stria farmac?utica. Heparina, um polissacar?deo sulfatado cuja presen?a j? foi identificada em v?rios invertebrados marinhos, destaca-se por sua extraordin?ria versatilidade funcional. Al?m de interferir na coagula??o sangu?nea, essa mol?cula possui grande potencial antiinflamat?rio. No entanto, sua forte atividade anticoagulante dificulta o aproveitamento cl?nico de sua propriedade antiinflamat?ria, o que estimula a pesquisa por an?logos de heparina com efeitos colaterais reduzidos. Diante disso, este trabalho teve por objetivos avaliar o efeito de um composto semelhante ? heparina (heparin?ide), isolado do cefalot?rax do camar?o Litopenaeus vannamei, sobre a resposta inflamat?ria, hemostasia e s?ntese de heparam sulfato antitromb?tico pelas c?lulas endoteliais, al?m de estudar alguns aspectos relevantes a cerca de sua estrutura. O heparin?ide purificado foi estruturalmente caracterizado seguindo uma abordagem anal?tica, envolvendo eletroforeses e cromatografias. As an?lises estruturais mostraram que esse composto possui um elevado conte?do de res?duos de ?cido glucur?nico e de dissacar?deos dissulfatados. Ao contr?rio da heparina de mam?feros, o heparin?ide foi incapaz de estimular a s?ntese de heparam sulfato pelas c?lulas endoteliais nas concentra??es testadas, al?m de apresentar atividade anticoagulante in vitro e efeito hemorr?gico reduzidos. Em um modelo de inflama??o aguda, o composto isolado do camar?o reduziu mais de 50% da infiltra??o celular. Al?m de reduzir a atividade de MMP-9 e proMMP-2 no lavado peritoneal dos animais submetidos ao modelo de inflama??o, o heparin?ide tamb?m reduziu a atividade de MMP-9 secretada por leuc?citos humanos ativados. Esses resultados demonstram o potencial do heparin?ide de L. vannamei em interferir em v?rios eventos da resposta inflamat?ria. Por possuir atividade anticoagulante e efeito hemorr?gico reduzidos, esse composto pode servir como um modelo estrutural para direcionar o desenvolvimento de agentes terap?uticos mais espec?ficos para o tratamento de doen?as inflamat?rias

Immune heparin-induced thrombocytopenia (HIT) is a potentially serious complication of heparin therapy and is associated with antibodies directed against a complex of platelet factor 4 (PF4) and heparin. Early diagnosis of HIT is important to reduce morbidity and mortality. I developed an enzyme immunoassay that detects the binding of HIT IgG to PF4-heparin in the fluid phase. This required techniques to purify and biotinylate PF4. The fluid phase assay produces consistently low background and can detect low levels of anti-PF4-heparin. It is suited to testing alternative anticoagulants because, unlike in an ELISA, a clearly defined amount of antigen is available for antibody binding. I was able to detect anti-PF4-heparin IgG in 93% of HIT patients. I also investigated cross-reactivity of anti-PF4-heparin antibodies with PF4 complexed to alternative heparin-like anticoagulants. Low molecular weight heparins cross-reacted with 88% of the sera from HIT patients while half of the HIT sera weakly cross-reacted with PF4-danaparoid (Orgaran). The thrombocytopenia and thrombosis of most of these patients resolved during danaparoid therapy, indicating that detection of low affinity antibodies to PF4-danaparoid by immunoassay may not be an absolute contraindication for danaparoid administration. While HIT patients possess antibodies to PF4-heparin, I observed that HIT antibodies will also bind to PF4 alone adsorbed on polystyrene ELISA wells but not to soluble PF4 in the absence of heparin. Having developed a technique to affinity-purify anti-PF4-heparin HIT IgG, I provide the first estimates of the avidity of HIT IgG. HIT IgG displayed relatively high functional affinity for both PF4-heparin (Kd=7-30nM) and polystyrene adsorbed PF4 alone (Kd=20-70nM). Furthermore, agarose beads coated with PF4 alone were almost as effective as beads coated with PF4 plus heparin in depleting HIT plasmas of anti-PF4-heparin antibodies. I conclude that the HIT antibodies which bind to polystyrene adsorbed PF4 without heparin are largely the same IgG molecules that bind PF4-heparin and thus most HIT antibodies bind epitope(s) on PF4 and not epitope(s) formed by part of a PF4 molecule and part of a heparin molecule. Binding of PF4 to heparin (optimal) or polystyrene/agarose (sub-optimal) promotes recognition of this epitope. Under conditions that are more physiological and sensitive than previous studies, I observed that affinity-purified HIT IgG will cause platelet aggregation upon the addition of heparin. Platelets activated with HIT IgG increased their release and surface expression of PF4. I quantitated the binding of affinity-purified HIT 125I-IgG to platelets as they activate in a plasma milieu. Binding of the HIT IgG was dependent upon heparin and some degree of platelet activation. Blocking the platelet Fc??? receptor-II with the monoclonal antibody IV.3 did not prevent HIT IgG binding to activated platelets. I conclude that anti-PF4-heparin IgG is the only component specific to HIT plasma that is required to induce platelet aggregation. The Fab region of HIT IgG binds to PF4-heparin that is on the surface of activated platelets. I propose that only then does the Fc portion of the bound IgG activate other platelets via the Fc receptor. My data support a dynamic model of platelet activation where released PF4 enhances further antibody binding and more release.

Immune heparin-induced thrombocytopenia (HIT) is a potentially serious complication of heparin therapy and is associated with antibodies directed against a complex of platelet factor 4 (PF4) and heparin. Early diagnosis of HIT is important to reduce morbidity and mortality. I developed an enzyme immunoassay that detects the binding of HIT IgG to PF4-heparin in the fluid phase. This required techniques to purify and biotinylate PF4. The fluid phase assay produces consistently low background and can detect low levels of anti-PF4-heparin. It is suited to testing alternative anticoagulants because, unlike in an ELISA, a clearly defined amount of antigen is available for antibody binding. I was able to detect anti-PF4-heparin IgG in 93% of HIT patients. I also investigated cross-reactivity of anti-PF4-heparin antibodies with PF4 complexed to alternative heparin-like anticoagulants. Low molecular weight heparins cross-reacted with 88% of the sera from HIT patients while half of the HIT sera weakly cross-reacted with PF4-danaparoid (Orgaran). The thrombocytopenia and thrombosis of most of these patients resolved during danaparoid therapy, indicating that detection of low affinity antibodies to PF4-danaparoid by immunoassay may not be an absolute contraindication for danaparoid administration. While HIT patients possess antibodies to PF4-heparin, I observed that HIT antibodies will also bind to PF4 alone adsorbed on polystyrene ELISA wells but not to soluble PF4 in the absence of heparin. Having developed a technique to affinity-purify anti-PF4-heparin HIT IgG, I provide the first estimates of the avidity of HIT IgG. HIT IgG displayed relatively high functional affinity for both PF4-heparin (Kd=7-30nM) and polystyrene adsorbed PF4 alone (Kd=20-70nM). Furthermore, agarose beads coated with PF4 alone were almost as effective as beads coated with PF4 plus heparin in depleting HIT plasmas of anti-PF4-heparin antibodies. I conclude that the HIT antibodies which bind to polystyrene adsorbed PF4 without heparin are largely the same IgG molecules that bind PF4-heparin and thus most HIT antibodies bind epitope(s) on PF4 and not epitope(s) formed by part of a PF4 molecule and part of a heparin molecule. Binding of PF4 to heparin (optimal) or polystyrene/agarose (sub-optimal) promotes recognition of this epitope. Under conditions that are more physiological and sensitive than previous studies, I observed that affinity-purified HIT IgG will cause platelet aggregation upon the addition of heparin. Platelets activated with HIT IgG increased their release and surface expression of PF4. I quantitated the binding of affinity-purified HIT 125I-IgG to platelets as they activate in a plasma milieu. Binding of the HIT IgG was dependent upon heparin and some degree of platelet activation. Blocking the platelet Fc??? receptor-II with the monoclonal antibody IV.3 did not prevent HIT IgG binding to activated platelets. I conclude that anti-PF4-heparin IgG is the only component specific to HIT plasma that is required to induce platelet aggregation. The Fab region of HIT IgG binds to PF4-heparin that is on the surface of activated platelets. I propose that only then does the Fc portion of the bound IgG activate other platelets via the Fc receptor. My data support a dynamic model of platelet activation where released PF4 enhances further antibody binding and more release.

Made available in DSpace on 2014-12-17T14:03:42Z (GMT). No. of bitstreams: 1 LucianaFC_DISSERT.pdf: 1219461 bytes, checksum: 86df41deecc523bb278b7a9bc3b86ec9 (MD5) Previous issue date: 2013-03-04 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / In recent years the heparin has been the subject of several studies that aim to expand its use as a therapeutic agent, due to its ability to modulate the activity of various proteins that play important roles in the regulation of pathophysiological processes. In several experiments and preclinical trials, heparin has demonstrated an anti-inflammatory role. However, its clinical use is limited, due to its strong anticoagulant activity and hemorrhagic complications. For this reason, considerable efforts have been employed in discovery of heparin analogous (heparinoid) with reduced side effects, that retain the anti-inflammatory properties of heparin. In this context, a heparinoid obtained from the head of Litopenaeus vannamei shrimp, which presents a structural similarity to heparin, showed, in previous studies, anti-inflammatory activity in a model of acute peritonitis with reduced anticoagulant effect in vitro and low hemorrhagic activity. Thus, the present work had as objective to evaluate the effect the heparinoid of the cephalothorax of gray shrimp on the acute inflammatory response in different times (3 or 6 hours after the induction of inflammatory stimulus), using the model of acute peritonitis induced in mice. It was also analyzed the HL effect over the activity of elastase, an enzyme involved in leukocyte recruitment. Furthermore to check if the different doses of heparin and heparinoid change the hemostatic balance in vivo, was assessed the effect of these compounds on the plasma clotting time in animals submitted to inflammation. The results show that in 3 hours, all doses of heparinoid were able to prevent efficiently in the acute inflammatory process without any anticoagulant effects, unlike the extrapolation dose of heparin, which has induced a large hemorrhage due its high anticoagulant activity. However, 6 hours after induction of inflammation, only the dosages of 0.1 and 1.0 μg/Kg of heparin and 1.0 μg/Kg of heparinoid kept anti-migratory effect, without changing of the hemostatic balance. These results indicate that the anti-migratory effect of theses compounds depends on the dosage and time of inflammatory stimulus. The HL and heparin were also able to inhibit the activity of the enzyme elastase. The discovery of this bioactive compound in the cephalothorax of shrimps can arouse great interest in biotechnology, since this compound could be useful as a structural model interesting for the development of new therapeutic agents for peritonitis / Nos ?ltimos anos a heparina tem sido alvo de diversos estudos que visam ampliar seu uso como agente terap?utico, devido ? sua habilidade de modular a atividade de v?rias prote?nas que desempenham pap?is importantes na regula??o de processos fisiopatol?gicos. Em diversos experimentos e ensaios pr?-cl?nicos, a heparina tem demonstrado papel anti-inflamat?rio. Entretanto, seu uso cl?nico ? limitado, devido ? sua forte atividade anticoagulante e complica??es hemorr?gicas. Por essa raz?o, consider?vel esfor?o tem sido empregado na descoberta de an?logos da heparina (heparin?ide) com reduzidos efeitos colaterais, que retenham as propriedades anti-inflamat?rias da heparina. Nesse contexto, um heparin?ide (HL) obtido da cabe?a do camar?o Litopenaeus vannamei, de semelhan?a estrutural ? heparina, apresentou em estudos pr?vios atividade anti-inflamat?ria em modelo de peritonite aguda, com reduzido efeito anticoagulante in vitro e baixa atividade hemorr?gica. Assim, o presente trabalho teve como objetivo avaliar o efeito deste heparin?ide sobre a resposta inflamat?ria aguda em diferentes tempos (3 ou 6 horas ap?s a indu??o do est?mulo inflamat?rio), utilizando o modelo de peritonite aguda induzida em camundongos. Foi analisado tamb?m o efeito do HL sobre a atividade da elastase, uma enzima envolvida no recrutamento de leuc?citos. Al?m disso, para verificar se as diferentes doses do heparin?ide e da heparina alteram o equil?brio hemost?tico in vivo, foi avaliado o efeito desses compostos sobre o tempo de coagula??o do plasma nos animais submetidos ? inflama??o. Os resultados revelam que em 3 horas, todas as doses do heparin?ide foram capazes de interferir de forma eficiente no processo inflamat?rio agudo sem apresentar efeito anticoagulante e interfer?ncia no equil?brio hemost?tico, ao contr?rio da dose de extrapola??o da heparina que induziu forte hemorragia, al?m de apresentar alta atividade anticoagulante. Entretanto, no tempo de 6 horas ap?s a indu??o da inflama??o, apenas as doses de 0,1 e 1,0 μg/Kg da heparina e 1,0 μg/Kg do heparin?ide mantiveram o efeito antimigrat?rio, sem alterar o equil?brio hemost?tico. Esses resultados indicam que o efeito antimigrat?rio depende do tempo e da dose administrada. O HL e a heparina tamb?m foram capazes de inibir a atividade da enzima elastase. A descoberta desse composto bioativo no cefalot?rax do camar?o poder? despertar grande interesse biotecnol?gico, pois este composto poderia servir como um modelo estrutural interessante para o desenvolvimento de novos agentes terap?uticos espec?ficos para a peritonite