Trypanosoma cruzi infection modulates secreted phospholipase A expression in the salivary glands of Rhodnius prolixus.

Phospholipases A (PLA) comprise a superfamily of enzymes that specifically catalyze hydrolysis of the ester bond at the sn-2 position of glycerophospholipids, generating lysophospholipids and fatty acids. In Rhodnius prolixus, one of the main vectors of the Chagas's disease etiologic agent Trypanosoma cruzi, it was previously shown that lysophosphatidylcholine, a bioactive lipid, found in the insect's saliva, contributes to the inhibition of platelet aggregation, and increases the production of nitric oxide, an important vasodilator. Due to its role in potentially generating LPC, here we studied the PLA present in the salivary glands of R. prolixus. PLA activity is approximately 100 times greater in the epithelium than in the contents of salivary glands. Our study reveals the role of the RpPLAXIIA gene in the insect feeding performance and in the fatty acids composition of phospholipids extracted from the salivary glands. Knockdown of RpPLAXIIA significantly altered the relative amounts of palmitic, palmitoleic, oleic and linoleic acids. A short-term decrease in the expression of RpPLAIII and RpPLAXIIA in the salivary glands of R. prolixus was evident on the third day after infection by T. cruzi. Taken together, our results contribute to the understanding of the role of PLA in the salivary glands of hematophagous insects and show that the parasite is capable of modulating even tissues that are not colonized by it.