Echinococcus multilocularis infection induces UBE2N suppression via exosomal emu-miR-4989

Extracellular vesicles secreted by Echinococcus multilocularis: important players in angiogenesis promotion

The involvement of Echinococcus multilocularis, and other parasitic helminths, in regulating host physiology is well recognized, but molecular mechanisms remain unclear. Extracellular vesicles (EVs) released by helminths play important roles in regulating parasite-host interactions by transferring materials to the host. Analysis of protein cargo of EVs from E. multilocularis protoscoleces in the present study revealed a unique composition exclusively associated with vesicle biogenesis. Common proteins in various Echinococcus species were identified, including the classical EVs markers tetraspanins, TSG101 and Alix. Further, unique tegumental antigens were identified which could be exploited as Echinococcus EV markers. Parasite- and host-derived proteins within these EVs are predicted to support important roles in parasite-parasite and parasite-host communication. In addition, the enriched host-derived protein payloads identified in parasite EVs in the present study suggested that they can be involved in focal adhesion and potentially promote angiogenesis. Further, increased angiogenesis was observed in livers of mice infected with E. multilocularis and the expression of several angiogenesis-regulated molecules, including VEGF, MMP9, MCP-1, SDF-1 and serpin E1 were increased. Significantly, EVs released by the E. multilocularis protoscolex promoted proliferation and tube formation by human umbilical vein endothelial cells (HUVECs) in vitro. Taken together, we present the first evidence that tapeworm-secreted EVs may promote angiogenesis in Echinococcus-infections, identifying central mechanisms of Echinococcus-host interactions.

Cysticercus pisiformis-derived novel-miR1 targets TLR2 to inhibit the immune response in rabbits

Cysticercosis pisiformis, a highly prevalent parasitic disease worldwide, causes significant economic losses in the rabbit breeding industry. Previous investigations have identified a novel microRNA, designated as novel-miR1, within the serum of rabbit infected with Cysticercus pisiformis. In the present study, we found that C. pisiformis-derived novel-miR1 was released into the rabbit serum via exosomes. Through computational analysis using TargetScan, miRanda, and PITA, a total of 634 target genes of novel-miR1 were predicted. To elucidate the functional role of novel-miR1, a dual-luciferase reporter assay was utilized and demonstrated that novel-miR1 targets rabbit Toll-like receptor 2 (TLR2). Rabbit peripheral blood lymphocytes (PBLCs) were transfected with novel-miR1 mimic and mimic NC, and the in vitro experiments confirmed that novel-miR1 suppressed the expression of pro-inflammatory cytokines such as TNF-α, IL-1β, and IL-6 through the nuclear factor kappa B (NF-κB) pathway. In vivo experiments demonstrated that novel-miR1 was significantly upregulated during the 1-3 months following infection with C. pisiformis in rabbits. Notably, this upregulation coincided with a downregulation of TLR2, P65, pP65, TNF-α, IL-1β, and IL-6 in PBLCs. Collectively, these results indicate that the novel-miR1 derived from C. pisiformis inhibited the rabbits' immune response by suppressing the NF-κB-mediated immune response. This immune modulation facilitates parasite invasion, survival, and establishment of a persistent infection.

Efficient delivery of Echinococcus multilocularis miRNAs using chitosan nanoparticles

Alveolar echinococcosis caused by Echinococcus multilocularis is an important zoonotic disease, a great threat to human health due to limited interventions. microRNAs are a type of small non-coding RNA that plays a key role in many diseases and is considered as a potential therapeutic target for control of parasitic diseases. However, naked miRNAs are difficult to enter into cells and are easily degraded in both external and internal environments. Chitosan (CS) has recently been used as a promising vehicle for delivery of nucleic acids. Therefore, we prepared miRNA-bearing CS nanoparticles and investigated the physicochemical properties as well as the delivery efficiency. We found that CS nanoparticles was relatively stable, offered miRNA strong protection from degradation and had low cytotoxicity with no significant effects on cell proliferation and apoptosis. CS nanoparticles were shown to be easily absorbed by cells and have remarkable liver tropism. Furthermore, CS nanoparticles were used to efficiently deliver E. multilocularis miR-4989 in vitro and in vivo and caused a significant reduction in the expression of UBE2N in the liver, a potential target of emu-miR-4989, at both mRNA and protein levels. Our data demonstrate that CS nanoparticles can act as a vehicle for efficient liver-targeted delivery of miRNAs and for development of miRNA-based therapeutics against E. multilocularis infection.