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Trypanosoma rangeli: a new perspective for studying the modulation of immune reactions of Rhodnius prolixus.

Garcia ES, Castro DP, Figueiredo MB, Genta FA, Azambuja P - Parasit Vectors (2009)

Bottom Line: Insects are exposed to a wide range of microorganisms (bacteria, fungi, parasites and viruses) and have interconnected powerful immune reactions.Although insects lack an acquired immune system they have well-developed innate immune defences that allow a general and rapid response to infectious agents.Over the last few decades we have observed a dramatic increase in the knowledge of insect innate immunity, which relies on both humoral and cellular responses.However, innate reactions to natural insect pathogens and insect-transmitted pathogens, such as parasites, still remain poorly understood.In this review, we briefly introduce the general immune system of insects and highlight our current knowledge of these reactions focusing on the interactions of Trypanosoma rangeli with Rhodnius prolixus, an important model for innate immunity investigation.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratório de Bioquímica e Fisiologia de Insetos, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Avenida Brasil 4365, Rio de Janeiro, 21045-900, RJ, Brazil. egarcia@fiocruz.br.

ABSTRACT
Insects are exposed to a wide range of microorganisms (bacteria, fungi, parasites and viruses) and have interconnected powerful immune reactions. Although insects lack an acquired immune system they have well-developed innate immune defences that allow a general and rapid response to infectious agents.Over the last few decades we have observed a dramatic increase in the knowledge of insect innate immunity, which relies on both humoral and cellular responses. However, innate reactions to natural insect pathogens and insect-transmitted pathogens, such as parasites, still remain poorly understood.In this review, we briefly introduce the general immune system of insects and highlight our current knowledge of these reactions focusing on the interactions of Trypanosoma rangeli with Rhodnius prolixus, an important model for innate immunity investigation.

No MeSH data available.


Related in: MedlinePlus

Phospholipids are hydrolyzed by phospholipase A2 liberating arachidonic acid and Lyso-PAF, regulators of insect's immune system. Arachidonic acid is the substrate for eicosanoid production, prostaglandins via cyclooxygenase and leukotrienes via lipoxygenase. Lyso-PAF is acetylated by PAF-acetyl transferase releasing PAF that can be degraded by PAF-acetyl hydrolase that hydrolyses PAF regenerating Lyso-PAF. In the presence of dexamethasone the immune responses are inhibited due to the suppression of phospholipase A2 activity with lower production of eicosanoids and PAF. On the other hand when exogenous arachidonic acid is added there is enhancement of eicosanoid production and immune responses increase.
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Figure 3: Phospholipids are hydrolyzed by phospholipase A2 liberating arachidonic acid and Lyso-PAF, regulators of insect's immune system. Arachidonic acid is the substrate for eicosanoid production, prostaglandins via cyclooxygenase and leukotrienes via lipoxygenase. Lyso-PAF is acetylated by PAF-acetyl transferase releasing PAF that can be degraded by PAF-acetyl hydrolase that hydrolyses PAF regenerating Lyso-PAF. In the presence of dexamethasone the immune responses are inhibited due to the suppression of phospholipase A2 activity with lower production of eicosanoids and PAF. On the other hand when exogenous arachidonic acid is added there is enhancement of eicosanoid production and immune responses increase.

Mentions: Miller and Stanley [33] have shown that eicosanoid biosynthesis inhibitors have a direct effect on Manduca sexta hemocytes and Tunaz et al. [34] demonstrated that dexamethasone exerts its effect on insects by inhibiting PLA2. Investigations made by Mandato et al. [25] showed that eicosanoid biosynthesis inhibitors attenuated the PO activity in Galleria mellonella challenged with bacteria, and this inhibitory effect of dexamethasone was abolished by the addition of arachidonic acid (Figure 3). So, many models of insect species have been studied to expand and generalize the hypothesis that eicosanoids mediate the nodule formation in insect hemolymph during immune responses to bacterial, fungal, parasitoid and viral infections.


Trypanosoma rangeli: a new perspective for studying the modulation of immune reactions of Rhodnius prolixus.

Garcia ES, Castro DP, Figueiredo MB, Genta FA, Azambuja P - Parasit Vectors (2009)

Phospholipids are hydrolyzed by phospholipase A2 liberating arachidonic acid and Lyso-PAF, regulators of insect's immune system. Arachidonic acid is the substrate for eicosanoid production, prostaglandins via cyclooxygenase and leukotrienes via lipoxygenase. Lyso-PAF is acetylated by PAF-acetyl transferase releasing PAF that can be degraded by PAF-acetyl hydrolase that hydrolyses PAF regenerating Lyso-PAF. In the presence of dexamethasone the immune responses are inhibited due to the suppression of phospholipase A2 activity with lower production of eicosanoids and PAF. On the other hand when exogenous arachidonic acid is added there is enhancement of eicosanoid production and immune responses increase.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2719633&req=5

Figure 3: Phospholipids are hydrolyzed by phospholipase A2 liberating arachidonic acid and Lyso-PAF, regulators of insect's immune system. Arachidonic acid is the substrate for eicosanoid production, prostaglandins via cyclooxygenase and leukotrienes via lipoxygenase. Lyso-PAF is acetylated by PAF-acetyl transferase releasing PAF that can be degraded by PAF-acetyl hydrolase that hydrolyses PAF regenerating Lyso-PAF. In the presence of dexamethasone the immune responses are inhibited due to the suppression of phospholipase A2 activity with lower production of eicosanoids and PAF. On the other hand when exogenous arachidonic acid is added there is enhancement of eicosanoid production and immune responses increase.
Mentions: Miller and Stanley [33] have shown that eicosanoid biosynthesis inhibitors have a direct effect on Manduca sexta hemocytes and Tunaz et al. [34] demonstrated that dexamethasone exerts its effect on insects by inhibiting PLA2. Investigations made by Mandato et al. [25] showed that eicosanoid biosynthesis inhibitors attenuated the PO activity in Galleria mellonella challenged with bacteria, and this inhibitory effect of dexamethasone was abolished by the addition of arachidonic acid (Figure 3). So, many models of insect species have been studied to expand and generalize the hypothesis that eicosanoids mediate the nodule formation in insect hemolymph during immune responses to bacterial, fungal, parasitoid and viral infections.

Bottom Line: Insects are exposed to a wide range of microorganisms (bacteria, fungi, parasites and viruses) and have interconnected powerful immune reactions.Although insects lack an acquired immune system they have well-developed innate immune defences that allow a general and rapid response to infectious agents.Over the last few decades we have observed a dramatic increase in the knowledge of insect innate immunity, which relies on both humoral and cellular responses.However, innate reactions to natural insect pathogens and insect-transmitted pathogens, such as parasites, still remain poorly understood.In this review, we briefly introduce the general immune system of insects and highlight our current knowledge of these reactions focusing on the interactions of Trypanosoma rangeli with Rhodnius prolixus, an important model for innate immunity investigation.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratório de Bioquímica e Fisiologia de Insetos, Instituto Oswaldo Cruz, Fundação Oswaldo Cruz, Avenida Brasil 4365, Rio de Janeiro, 21045-900, RJ, Brazil. egarcia@fiocruz.br.

ABSTRACT
Insects are exposed to a wide range of microorganisms (bacteria, fungi, parasites and viruses) and have interconnected powerful immune reactions. Although insects lack an acquired immune system they have well-developed innate immune defences that allow a general and rapid response to infectious agents.Over the last few decades we have observed a dramatic increase in the knowledge of insect innate immunity, which relies on both humoral and cellular responses. However, innate reactions to natural insect pathogens and insect-transmitted pathogens, such as parasites, still remain poorly understood.In this review, we briefly introduce the general immune system of insects and highlight our current knowledge of these reactions focusing on the interactions of Trypanosoma rangeli with Rhodnius prolixus, an important model for innate immunity investigation.

No MeSH data available.


Related in: MedlinePlus