Modulation of ROS production in human leukocytes by ganglioside micelles

Recent studies have reported that exogenous gangliosides, the sialic acid-containing glycosphingolipids, are able to modulate many cellular functions. We examined the effect of micelles of mono- and trisialoganglioside GM1 and GT1b on the production of reactive oxygen species by stimulated human polymorphonuclear neutrophils using different spectroscopic methods. The results indicated that exogenous gangliosides did not influence extracellular superoxide anion (O2.-) generation by polymorphonuclear neutrophils activated by receptor-dependent formyl-methionyl-leucyl-phenylalanine. However, when neutrophils were stimulated by receptor-bypassing phorbol 12-myristate 13-acetate (PMA), gangliosides above their critical micellar concentrations prolonged the lag time preceding the production in a concentration-dependent way, without affecting total extracellular O2.- generation detected by superoxide dismutase-inhibitable cytochrome c reduction. The effect of ganglioside GT1b (100 µM) on the increase in lag time was shown to be significant by means of both superoxide dismutase-inhibitable cytochrome c reduction assay and electron paramagnetic resonance spectroscopy (P < 0.0001 and P < 0.005, respectively). The observed phenomena can be attributed to the ability of ganglioside micelles attached to the cell surface to slow down PMA uptake, thus increasing the diffusion barrier and consequently delaying membrane events responsible for PMA-stimulated O2.- production.

Protein kinase A mediates microglial activation induced by plasminogen and gangliosides

In the injured brain, microglia is known to be activated and produce proinflammatory mediators such as interleukin-1beta (IL-1beta), tumor necrosis factor-alpha (TNF-alpha) and inducible nitric oxide synthase (iNOS). We investigated the role of protein kinase A (PKA) in microglial activation by both plasminogen and gangliosides in rat primary microglia and in the BV2 immortalized murine microglial cell line. Both plasminogen and gangliosides induced IL-1beta, TNF-alpha and iNOS mRNA expression, and that this expression was inhibited by the addition of the PKA inhibitors, KT5720 and H89. Both plasminogen and gangliosides activated PKA and increased the DNA binding activity of the cAMP response element- binding protein (CREB). Furthermore, KT5720 and H89 reduced the DNA binding activities of CREB and NF-kappaB in plasminogen-treated cells. These results suggest that PKA plays an important role in plasminogen and gangliosides- induced microglial activation.

Effects of ganglioside on paclitaxel (Taxol) induced neuropathy in rats.

The effects of ganglioside on paclitaxel induced neuropathy were studied in 15 female Wistar rats. The animals were equally divided into 3 groups based on the type of administrated drug. The first (C-group) received an intraperitoneal weekly injection of 1 ml of NSS for five weeks. The second (P-group) received 9 mg/kg of a paclitaxel intraperitoneal weekly injection for five weeks. The third (PG-group) received both ganglioside and paclitaxel. Sensory evaluation and electrophysiologic studies of the tail nerve were performed before the administration of the first dose and at the end of the experiment. Morphological evaluation of the sciatic nerve was also studied. The results revealed the mean reaction time of the tail flick test, latency, amplitude and nerve conduction velocity of the P-group in the first and seventh week were of significant difference. However, there was no significant difference detected in those of the C-group and the PG-group. There was significant difference in all parameters between the PG and P-groups but not between the PG and C-groups. Cross sections of the sciatic nerve in the P-group showed mild endoneurium edema and some degenerated axons. Small myelinated nerve fibers in the PG-group were prominent. The results of this study indicated that ganglioside treatment could produce some beneficial effects in an animal model of paclitaxel induced neuropathy.

Efecto de gangliosidos in vitro sobre linfocitos de pacientes chagasicos estimulados con mitogenos o con antigenos de corazón o cerebro / Gangliosides in vitro effects on lymphocytes from patients with chronic Chagas disease stimulated with mitogens or heart or brain antigens

Se estudió in vitro el efecto de gangliósidos sobre las respuestas de linfocitos de pacientes chagásicos estimulados con mitógenos o con antígenos de corazón y cerebro. La razón para efectuar este estudio fueron las evidencias que indican un rol de los linfocitos T en la producción de daños de la cardiopatía chagásica, y datos que indican que los gangliósidos pueden tener actividad sobre esas células. Además, en trabajos previos, hallamos que los linfocitos de chagásicos responden con transformación blástica (TB). Material y Métodos: se efectuaron cultivos de leucocitos de 14 pacientes chagásicos. A los cuales se adicionaron gangliósidos y en esas condiciones, se estimularon con mitógenos, o bien con antígenos de corazón humano o cerebro murino, respectivamente. Resultados: se observó inhibición parcial de la transformación blástica Inducida por mitógenos, y también hubo Inhibición parcial de la TB inducible por los antígenos de corazón o de cerebro en los linfocitos de chagásicos, siendo significativas las diferencias con respecto a los controles (p< 0.001). Conclusiones: se considera de Interés ese efecto inhibidor de gangliósidos sobre las actividades de los linfocitos de chagásicos estudiadas en estos experimentos, por ser directamente vinculables a factores de patogenia chagásica, que podrían ser Inmunomodulados.

In human Chagas'disease previous work has shown the occurrence of a T-lymphocyte CD4-positive population (a high producer of PAS-positive glycoproteins) with evidence suggesting a role in the formation of damages to the myocardium and neural structures in chagasic heart disease (ChHD). Other workers have taken such facts into consideration and have employed gangliosides (biological substances with neurotrophic and immunomodulatory properties) in chagasics with chronic cardiomyopathy and disautonomic signs, obtaining an Improvement in functional signs and a decrease in the number of PAS+ lymphocytes. In the present work we have studied the effect of mixed gangliosides (Cronassial on cell cultures of total leukocytes, or on mononuclear cells prepared through Ficoll-Hypaque. Blood was obtained from 14 patients with ChHD. Experiments were undertaken to assess the effect of policlonal mitogens Phytohaemagglutinin (Phy) and Concanavalin A (Con A) on blastic transformation, estimated by cell size and cytologic study. In addition, the production of PAS+ substances by the lymphocytes and blast were assessed. Gangliosides were added at final concentrations of 100 mg/ml or 200 mg/ ml. Cell viability was assessed by means of the Trypan blue test. With respect to blastic transformation, results showed a significant decrease in the cultures that received gangliosides 24 hours before mltogen administration, as compared with controls (p<0.001) (both for Phy and Con A). On the other hand, the production of lymphocytic PAS+ substances decreased in the cultures of chagasics in which gangliosides were added. Some of these results confirmed previous findings on the matter. The facts suggest that gangliosides can modulate some lymphocytic activities in chagasics.

Inhibition of mouse and rat lymphoproliferation by gangliosides

Our previous study have demonstrated that Glycosphingolipids (GSLs) have an immunosuppressive effect on murine lymphoproliferation and IL-2 production. In the present study we examined the effect of a pool of Gangliosides (Gang) on spleen lymphocyte proliferation from either isogeneic strains of Wistar rats or BALB/c mice. Two hundred-fifty grams adult female isogeneic Wistar rats and 8-week-old BALB/c mice were used. The animals were sacrificed and the spleen harvested aseptically for cellular assays. Spleen cells suspensions were obtained by homogenization in RPMI 1640 with a loose tissue grinder. After washing, the cells were suspended in RPMI 1640 supplemented. Cell viability was measured by Trypan blue exclusion. Cells were cultured in triplicate using increasing concentrations of Gang (1; 2; 5; 10; 15; 20 mg/well) and in the presence of Concanavalin A. The cells were incubated for 48 hours and were pulsed with [3H] thymidine 18 hours prior to harvesting on glass fiber paper for counting in a beta-counter. Data were presented as rate of inhibition, as previously described. At concentrations 1 and 2 mug/well, Gang stimulated lymphoproliferation (30 percent and 50 percent, rats and mice respectively), while at concentration from 5 to 20 mg/well an increasing inhibition was observed for spleen cells from both mouse and rat (from 40 percent up to 80 percent). In preliminary studies we observed inhibition of mixed lymphocyte reaction on spleen cells from rats treated with Gang for 10 days (data not shown). Our data suggest that Gang may be investigated as a immunosuppressive drug in organ transplantation.

Efeito imunossupressor dos gangliosídeos: estudo in vivo / Immunosupressive effect of gangliosides: in vivo study

Imunomodulação mais específica e eficaz é uma meta importante a ser atingida na área de órgão. Neste sentido, foi estudado previamente o papel imunomodulador dos gangliosídeos "in vitro". No presente trabalho objetivou-se avaliar este efeito agora "in vivo", mimetizando a situação do transplante alogênico. Foram utilizados 26 ratos Wistar 1 EPM, machos, com 3 meses de idade, pesando cerca de 250g, procedentes do Centro de Desenvolvimento de Pesquisa Experimental em Medicina e Biologia. Os animais fora mantidos por 5 dias, para adaptação, no biotério setorial da Disciplina de Técnica Operatória e Cirurgia Experimental da UNIFESP-EPM, recebendo água e ração própria para a espécie. Os animais foram distribuídos em grupos conforme segue: grupos experimento (que receberam 1, 3 e 6 mg/kg/dia de gangliosídeos) e um grupo controle que recebeu veículo, todos por via intramuscular durante 7 dias consecutivos. No 8º dia, com os animais anestesiados com éter etílico foi feita a remoção cirúrgica do baço de todos os animais, os quais foram sacrificados por exsanguinação, ainda sob efeito anestésico. Os baços removidos foram processados para a obtenção de linfócitos os quais foram cultivados em placa de cultura com 96 poços, distribuídos da seguinte forma: 1,5x10(5) linfócitos viáveis de cada animal dos grupos experimento e controle foram cultivados com 1,5x10(5) linfócitos viáveis de um rato não tratado, sendo assim realizada a reação mista de linfócitos. Os linfócitos provenientes dos animais dos grupos controle e 1 mg apresentaram aumento da proliferação sem nenhuma alteração. Por outro lado, foi observada uma taxa de inibição ao redor de 70 por cento sobre a proliferação linfocitária dos animais dos grupos 3 e 6 mg comparados aos animais dos grupos controle e 1 mg. O resultado desta investigação estimula a utilização dos gangliosídeos no tratamento da rejeição alogênica.

Gangliosideos: estudo do colágeno e da resposta inflamatória no processo cicatricial / Gangliosides: study of colagem and the inflamatory response in cicatricial process

Objetivo: Investigar o efeito dos gangliosídeos sobre a infiltração seqüencial de leucócitos e fibroblastos durante o processo de cicatrização usando um modelo de cicatrização da pele em ratos. Método: Foram utilizados 12 ratas EPM - 1 Wistar, com peso médio de 200 gramas e 4 meses de idade. Os animais procederam do Centro de Desenvolvimento de Pesquisa Experimental em Medicina e Biologia e foram mantidos por 5 dias para adaptação no biotério setorial da disciplina de Técnica Operatória e Cirurgia Experimental da UNIFESP-EPM, recebendo água e ração própria para a espécie. O protocolo anestésico utilizado foi uma associação de Cetamina (60mg.kg-1) e Xilazina (10mg.kg-1), por via intramuscular. Em seguida, realizava-se uma incisão longitudinal com 7 cm de extensão, na região dorsal paravertebral, interessando pele e tela subcutânea que foi fechada com pontos separados, com fio de prolene 7-0 e agulha triangular. As ratas foram distribuídas em dois grupos a saber: grupo experimento, que recebeu 3mg.kg-1.dia-1 de gangliosídeos, e um grupo controle, que recebeu veículo, ambos por via intramuscular durante 14 dias consecutivos. No 7º e 14º dias de pós-operatório foram ressecados fragmentos da pele e tela subcutânea para análise histológica, com a coloração de Tricrômio de Masson e Hematoxilina - Eosina. Resultados: As amostras apresentaram a mesma quantidade de colágeno em ambos os grupos mostrando que não houve inibição dos fibroblastos. Entretanto, a infiltração leucocitária foi retardada no grupo experimento quando comparado ao grupo controle. Conclusão: A alteração encontrada no processo cicatricial foi devida a um retardo na resposta inflamatória e não a uma inibição fibroblastos.

Neutralization of the effect of Crotalus durissus terrificus venom by gangliosides

We determined the ability of a mixture of gangliosides (16 percent) GDlb, 19 percent GT1b, 21 percent GM1, 40 percent GD1a) to neutralize the effect of Crotalus durissus terrificus (Cdt) venom in vitro and in vivo. Protection was indicated by the absence of muscular contractions, hind limb paralysis or death of BLB/c mice (16-18g) after receiving Cdt venom (1µgCdt venom containing 0.6 µg protein) at the doses indicated. A dose of Cdt venom above 0.9µg (ip) or 1 µg (im) induced muscular contraction and above 1.2 µg (ip) or 5.5 µg (im) the venom induced muscular contraction and hind limb paralysis. Cdt venom BOVE 2.5 µG (IP) OR 9 µg (im) induced all these symptoms and 95 to 100 percent death in experimental animals. The lethal dose 50 percent of the Cdt venom used was 8µ (im) and 1.5 µg (ip). In vitro studies, 4 mg gangliosides neutralized the effect of up to 1.5 µg Cdt venom. Quantities as low as 0.2 mg gangliosides were capable neutralizing 0.9 µg of Cdt venom in vitro. Intramuscular treatment with 1 mg gangliosides performed 60 min after the intramuscular injection of 5 µg Cdt venom protected 100 percent of the animals. In contrast, no protection was achieved with intraperitoneal treatment with gangliosides. The data show that gangliosides were effective in neutralizing the toxic effect induced by Crotalus durissus terrificus venom both in vitro and in vivo and that post-exposure intramuscular treatment with gangliosides could protect animals experimentally inoculated with the venom

Células ciliadas isoladas em cultura: um novo modelo para estudo da ototoxicidade / Ciliated cells isolated in culture: a new model for the study of otoxicity

A otoxicidade da Amicacina e a proteçäo por gangliosídeos das células ciliadas externas (CCE) cocleares de cobaias foram estudadas com 3 grupos de 8 animais. O grupo I, controle, o grupo II recebeu Amicacina e o grupo III Amicacina e gangliosídeo. utilizando-se o método de isolamento mecânico das CCE em cultura, 179 +-33 células em cada cobaia normal foram encontradas conservando suas características vitais até 2 horas e meia. O padräo de degeneraçäo vital foi observado e descrito. As lesöes provocadas pela Amicacina foram intensas. A análise estatística foi significativa na comparaçäo entre o grupo I e os grupos II e III, mas o resultado entre os grupos II e III näo demonstraram efeitos significativos na proteçäo das células pelos gangliosídeos contra os efeitos da Amicacina. Concluiu-se que esta técnica utilizada pela primeira vez para estudo da otoxicidade, constitui um modelo válido importante, simples e rápido, que permite estudo minucioso das lesöes em células isoladas "in vitro" provocadas por drogas ototóxicas

Exogenous ganglioside stimulation of axonal regeneration after new transection and entubulation repair

Adult male mice received sciatic nerve transection at the midthigh level and both nerve stumps were sutured into a polythylene tube (PT) to bridge a nerve gap of 4 mm. The tubes were implanted either empty, or filled with collagen alone or in combination with gangliosides (GM1, GD1a, GD1b, anhd GT1b). Following a survival time of 6 weeks, the PT with the regenerating nerve cables were processed for plastic embedding, and morphometric measurements were made on myelinated and unmyelinated axons. The data suggest that local application of exogenous gangliosides causes a stimulation of axonal sprouting in vivo with no effefct on the rate of axonal maturation