TLR2 and MyD88 are implicated in functional response of macrophages to a phospholipase A2 isolated from snake venom

LEIGUEZ, ELBIO; GIANNOTTI, K. C.; MOREIRA, V.; MATSUBARA, M. H.; GUTIERREZ, J. M.; LOMONTE, B.; RODRIGUEZ JUAN PABLO; BALSINDE, JESÚS; TEIXEIRA, C.

Natal, Rio Grande do Norte

Conferencia; 11th World congress of inflammation and XXXVIII Congress of the Brazilian Society of Immunology; 2014

The snake venom MT-III is a group IIA secretory phospholipase A2 (sPLA2) enzyme with functional and structural similarities with mammalian pro-inflammatory sPLA2s of the same group. Previously, we demonstrated that MT-III directly activates the innate inflammatory response of macrophages, including release of inflammatory mediators and lipid droplets (LDs) formation. However, the mechanisms coordinating these processes remain unclear. In the present study, by using TLR2-/- or MyD88-/- or C57BL/6 (WT) male mice, we report that TLR2 and MyD88 signaling have a critical role in MT-III- induced inflammatory response in macrophages. MT-III caused a marked release of PGE2, PGD2, PGJ2, IL-1β and IL-10 and increased the number of LDs in WT macrophages. In MT-III-stimulated TLR2-/- macrophages, formation of LDs and release of eicosanoids and cytokines were abrogated. In MyD88-/- macrophages, MT-III-induced release of PGE2, IL1β and IL-10 was abrogated, but release of PGD2 and PGJ2 was maintained. In addition, COX-2 protein expression seen in MT-III- stimulated WT macrophages was abolished in both TLR2-/- and MyD88-/- cells, while PLIN2 expression was abolished only in MyD88-/- cells. We further demonstrated a reduction of saturated, monounsaturated and polyunsaturated fatty acids and a release of the TLR2 agonists palmitic and oleic acid from MT-III-stimulated WT macrophages compared with WT control cells, thus suggesting these fatty acids as major messengers for MT-III-induced engagement of TLR2/MyD88 signaling. Collectively, our findings identify for the first time a TLR2 and MyD88- dependent mechanism that underlies group IIA sPLA2-induced innate response in macrophages.