VIP and conditioned media from trophoblast cells inhibit autophagic processes in neutrophils and promote their apoptosis through activation of cAMP-PKA pathway.

G. CALO, I. KEITELMAN, F. SABBIONE, D. VOTA, D. PAPARINI, R. RAMHORST, A. TREVANI AND C. PÉREZ LEIRÓS

Buenos Aires

Congreso; Reunión Conjunta de Sociedades Biomédicas; 2017

Reunión Conjunta de Sociedades Biomédicas

Trophoblast cells (Tb) interact with different maternal immune cell populations at early pregnancy promoting an anti-inflammatory and tolerogenic response. Neutrophils (neu) are short-lived cells and apoptosis is considered to be the major death mechanism. Autophagy and apoptosis cooperate to modulate neu survival. Failure to properly regulate neu abundance and turnover can contribute to human disease. In addition, efferocytosis of dying neu dampens proinflammatory cytokine production and reprograms macrophages to a pro-resolution phenotype. Vasoactive Intestinal Peptide (VIP) is a pleiotropic peptide with immunomodulatory effects through its action on VPAC1 and VPAC2 receptors, both coupled to the activation of adenylate cyclase and protein kinase A (PKA). We have already shown that VIP and conditioned media (CM) from human first trimester Tb (Swan-71 cell line) inhibit PMA-induced NET formation, promote neutrophil apoptosis and revert the anti-apoptotic effect of LPS. Our aim was to evaluate the effect of VIP and Tb derived factors on neu autophagy and the mechanisms involved in neu apoptosis and efferocytosis.Whole blood was obtained from healthy donors and neu purified on a Ficoll-Paque PLUS gradient and Dextran sedimentation. We found that CM and VIP inhibit PMA-induced autophagy, quantified by fluorescence intensity of LC3 puntae by confocal microscopy (p≤0.05). On the other hand, H89 a PKA inhibitor, blocks the pro-apoptotic effect of VIP on neu apoptosis (p≤0.05), determined by fluorescence microscopy with ethidium bromide and acridine orange. Moreover, the release of elastase, known to prevent efferocytosis, was reduced when neu were stimulated with PMA + VIP or CM, compared to PMA alone as evaluated by flow citometry. We conclude that VIP and Tb factors regulate autophagic and apoptotic processes in neu and suggests that they contribute to the maintenance of an anti-inflammatory microenvironment during early pregnancy