Angiostrongylus cantonensis Galectin-1 interacts with Annexin A2 to impair the viability of macrophages via activating JNK pathway

Abstract

Background: Angiostrongylus cantonensis can cause severe symptoms of central nervous system infections. In the host, this parasite localizes in the blood and cerebrospinal fluid, and its secreted components can impact immune responses. Our previous study demonstrated that immune responses were inhibited in A. cantonensis-infected mice immunized with Ac-Galectin-1 (AcGal-1). However, the mechanisms by which AcGal-1 regulates the immune responses remain unclear. Macrophages are innate immune cells that rapidly respond to infection. The direct impact of AcGal-1 on macrophages may affect the immune responses.Methods: AcGal-1 protein was purified by nickel ion affinity chromatography. The effect of AcGal-1 on the apoptosis of macrophages was detected using CCK-8 assay, flow cytometry and western blot. Macrophage membrane proteins bound to AcGal-1 were obtained using the His-tag-based pull-down assay and identified via mass spectrometry. Co-localization of AcGal-1 and the macrophage membrane protein Annexin A2 was observed by immunofluorescence microscopy, and their interaction was validated by co-immunoprecipitation experiments. SiRNA-mediated knockdown of Annexin A2 was used to determine if AcGal-1-induced macrophage apoptosis required interaction with Annexin A2. The phosphorylation level of apoptotic signal pathway protein was detected by phospho-antibody microarray and western blot. Results:Our study showed that AcGal-1 caused apoptosis of the macrophages. AcGal-1 increased the expression of apoptosis proteins caspase-3, caspase-9, Bax, but reduced the expression of anti-apoptosis protein Bcl-2. AcGal-1 interacted with the membrane protein Annexin A2, and knockdown of Annexin A2 expression increased Bcl-2 but decreased Bax levels in AcGal-1-treated cells. Moreover, AcGal-1 increased JNK phosphorylation and the inhibition of JNK phosphorylation in AcGal-1-treated cells decreased the expression of caspase-3, -9, Bax and almost restored Bcl-2 to the level observed in control cells. Conclusions:AcGal-1 can induce the apoptosis of macrophages by binding to Annexin A2 and activating JNK downstream the apoptotic signaling pathway.

The interaction of host and nematode galectins influences the outcome of gastrointestinal nematode infections

“…In mice, vaccination against Angiostrongylus cantonensis galectin inhibits the immune response to subsequent infection with A. cantonensis (Yan et al ., 2018). Angiostrongylus cantonensis gal-1 causes apoptosis of macrophages by binding to Annexin A2 and activating the apoptotic signalling pathway (Shi et al ., 2020).…”

“…In mice, vaccination against Angiostrongylus cantonensis galectin inhibits the immune response to subsequent infection with A. cantonensis (Yan et al, 2018). Angiostrongylus cantonensis gal-1 causes apoptosis of macrophages by binding to Annexin A2 and activating the apoptotic signalling pathway (Shi et al, 2020). The changes in mucus following infection are at least partly host-mediated and widely assumed to benefit the host (Knight et al, 2011;Hasnain et al, 2017).…”

Upregulated galectin-1 in Angiostrongylus cantonensis L5 reduces body fat and increases oxidative stress tolerance

“…Galectins are secreted by cells via an unconventional mechanism [ 21 , 22 ] and function in various biological phenomena, such as development, immunity and tumorigenesis via recognition of cell surface or extracellular glycoconjugates [ 22 ]. Parasite galectins have a sequence and structure similar to those of mammalian homologs and are presumed to participate in host-parasite interactions [ 23 , 24 ]. Our previous studies showed that upregulated Acan -Gal-1 in A. cantonensis L5 induced the apoptosis of macrophages by binding to Annexin A2 and activating the JNK apoptotic signaling pathway [ 24 ].…”

Up-Regulated Galectin-1 in Angiostrongylus Cantonensis L5 Reduces Body Fat and Increases Oxidative Stress Tolerance

“…Galetins are secreted by cells via an unconventional mechanism [21,22], and function in various biological phenomena, such as development, immunity and tumourigenesis via recognition of cell surface or extracellular glycoconjugates [22]. Parasite Galetins have a sequence and structure similar to those of mammalian homologs and are presumed to participate in host-parasite interactions [23,24].Our previous studies showed that up-regulated Acan-Gal-1 in A. cantonensis L5 induced the apoptosis of macrophages by binding to Annexin A2 and activating the JNK apoptotic signaling pathway [24]. However, galectins are also found intracellularly, and are involved in RNA splicing, cell growth, apoptosis and other functions [25,26].…”

“…As LEC-1 is mainly localized in the cuticle and pharynx of C. elegans [32], it is thought to have some functions as a component of the durable outer barrier via recognizing and cross-linking glycoconjugates by its two CRDs with different sugar-binding properties, and play a defensive role against damage due to oxidative stress in C. elegans [33]. Therefore, Acan-Gal-1, up-regulated in A. cantonensis L5, may have function of resisting immune attacks in human by not only inducing the apoptosis of its host's macrophages extracellularly [24], but also increasing oxidative stress tolerance of the worm itself intracellularly.…”