Wnt5a Signaling Promotes Host Defense againstLeishmania donovaniInfection

Abstract

Leishmania donovani infects macrophages, disrupting immune homeostasis. The underlying mechanism that sustains infection remains unresolved. In view of the potential of Wnt5a signaling to support immune homeostasis, we evaluated the interrelationship of Wnt5a signaling and Leishmania donovani infection. Upon infecting macrophages separately with antimony drug–sensitive and –resistant L. donovani, we noted disruption in the steady-state level of Wnt5a. Moreover, inhibition of Wnt5a signaling by small interfering RNA transfection in vitro or by use of inhibitor of Wnt production in vivo led to an increase in cellular parasite load. In contrast, treatment of macrophages with recombinant Wnt5a caused a decrease in the load of antimony-sensitive and -resistant parasites, thus confirming that Wnt5a signaling antagonizes L. donovani infection. Using inhibitors of the Wnt5a signaling intermediates Rac1 and Rho kinase, we demonstrated that Wnt5a-mediated inhibition of parasite infection in macrophages is Rac1/Rho dependent. Furthermore, phalloidin staining and reactive oxygen species estimation of Wnt5a-treated macrophages suggested that a Wnt5a-Rac/Rho–mediated decrease in parasite load is associated with an increase in F- actin assembly and NADPH oxidase activity. Moreover, live microscopy of L. donovani–infected macrophages treated with Wnt5a demonstrated increased endosomal/lysosomal fusions with parasite-containing vacuoles (parasitophorous vacuoles [PV]). An increase in PV–endosomal/lysosomal fusion accompanied by augmented PV degradation in Wnt5a-treated macrophages was also apparent from transmission electron microscopy of infected cells. Our results suggest that, although L. donovani evades host immune response, at least in part through inhibition of Wnt5a signaling, revamping Wnt5a signaling can inhibit L. donovani infection, irrespective of drug sensitivity or resistance.

Wnt5A Signaling AntagonizesLeishmania donovaniInfection

“…The decrease in the parasite load was seen to be dose and time dependent. Interestingly, a decrease in parasite load was also seen when Wnt5A was exogenously added to infected macrophages, suggesting that there may be a therapeutic role of Wnt5A signaling during L. donovani infection [42]. Depletion of Wnt5A signaling through application of IWP-2 or transfection with Frizzled5 (putative receptor to Wnt5A) siRNA resulted in enhancement of infection by L. donovani, corroborating the importance of Wnt5A signaling in limiting L. donovani infection.…”

“…It is now known that Wnt5A signaling plays an important role in stimulating microbial phagocytosis and sustenance of immune homeostasis through alteration in actin assembly and maintenance of an appropriate cytokine milieu [40][41][42][43]. The role of WNT5A signaling in stimulating microbial phagocytosis has been shown to be dependent on Rac GTPase and Rho GTPase activity in macrophages [41].…”

“…Alteration of cytoskeletal dynamics by Wnt5A signaling therein may be correlated with better assembly of NADPH oxidase subunits on phagosomal membranes and efficient production of microbicidal ROS [45,46]. The increase in phagocytic activity and microbial killing by Wnt5A signaling may also be dependent upon the change in lipid raft organization of the macrophages in association with actin assembly [41][42][43]. Suppression of Wnt5A production by IWP2 (Inhibitor of Wnt production-2) accordingly abrogates both phagocytic activity and microbial killing in macrophages [40,41,47].…”

“…using live cell dyes [42]. Electron microscopic (EM) images showed Wnt5A induced increased membranous vesicle fusions with PV in the infected cells.…”

Wnt5a is involved in LOX‐1 and TLR4 induced host inflammatory response in peri‐implantitis

“…In contrast to the anti‐inflammatory functions of the canonical Wnt signaling pathway, the non‐canonical pathway regulates pro‐inflammatory responses . The wingless‐type MMTV integration site family member 5A (Wnt5a) is the activating ligand of the non‐canonical Wnt signaling pathway and contributes to the inflammatory response to pathogens . Previous studies showed that Wnt5a binds to the secreted frizzled‐related protein 5 to reduce inflammatory cytokine production via the JNK pathway .…”