Schistosoma japonicum extracellular vesicle miRNA cargo regulates host macrophage functions facilitating parasitism

Among-population proteomic differences in Schistocephalus solidus based on excretory/secretory and total body protein predictions

BACKGROUND

Parasites secrete and excrete a variety of molecules that evolved to help establish and sustain infections within hosts. Parasite adaptation to their host may lead to between-population divergence in these excretory and secretory products (ESPs), but few studies have tested for intraspecific variation in helminth proteomes.

METHODS

Schistocephalus solidus is a cestode that parasitizes the threespine stickleback, Gasterosteus aculeatus. We used an ultra-performance liquid chromatography-mass spectrometry protocol to characterize the ESPs and whole-body proteome of S. solidus. Specifically, we characterized the proteome of S. solidus at the plerocercoid stage from wild-caught stickleback from three lakes on Vancouver Island (British Columbia, Canada) and one lake in Alaska (USA). We tested for differences in proteome composition among the four populations and specifically between ESPs and body tissue.

RESULTS

Overall, we identified 1362 proteins in the total proteome of S. solidus, with 542 of the 1362 proteins detected exclusively in the ESPs. Of the ESP proteins, we found signaling peptides and transmembrane proteins that had not been previously detected or characterized in S. solidus. We also found that protein spectrum counts varied greatly among all lake populations.

CONCLUSIONS

These population-level differences were observed in both ESP and whole-body tissue types. Our study suggests that S. solidus can excrete and secrete a wide range of proteins which are distinct among populations. These differences might reflect plastic responses to host genotype differences, or evolved adaptations by Schistocephalus to different local host populations.

Comparative microRNAs profile of Schistosoma japonicum male worms derived from single-sex and bisexual infections: Implications of the multifunctional role of microRNA

Schistosoma japonicum is a dioecious parasite that requires constant pairing between male and female worms for female maturation and egg production. MicroRNAs (miRNAs) play crucial roles in regulating various biological processes, including parasite development and host-pathogen interactions, but their functions in schistosomes remain largely unexplored. This study aimed to investigate the differentially expressed miRNAs (DEMs) between mated male (MM) and single-sex male (SM) worms to gain insights into their regulatory roles in schistosome reproduction. Total RNA was extracted from 28-day-old MM and SM worms, followed by small RNA sequencing to identify DEMs. Bioinformatics analyses were used to predict the biological functions of DEM target genes. Comparative analysis with previously published miRNA datasets helped identify potentially significant miRNAs. Quantitative PCR (qPCR) validated the expression of selected miRNAs and mRNA levels of some target genes. A total of 20 DEMs were identified, with 9 upregulated in MM worms and 11 in SM worms. These DEMs may regulate processes such as intracellular transport, RNA processing, and cellular homeostasis. The study provides novel insights into the biological differences between SM and MM worms, suggesting that these miRNAs could be key regulators of parasite development and host adaptation, with potential diagnostic and therapeutic applications in schistosomiasis.

A non-vesicular Argonaute protein is transmitted from nematode to mouse and is important for parasite survival

Argonautes are ancient proteins with well-characterised functions in cell-autonomous gene regulation and genome defense but less clear roles in non-cell-autonomous processes. Extracellular Argonautes have been reported across plants, animals and protozoa yet their biochemical and functional properties remain elusive. Here we demonstrate that an extracellular Argonaute (exWAGO) released by the rodent-infective parasitic nematode Heligmosomoides bakeri is detectable inside mouse cells during the natural infection. We further show that exWAGO is released from H.bakeri in both vesicular and non-vesicular forms that have different resistances to proteolysis, different accessibilities to antibodies and associate with different subsets of secondary siRNAs. Using recombinant exWAGO protein we demonstrate that non-vesicular exWAGO is directly internalised by mouse cells in vitro and that immunisation of mice with exWAGO confers partial protection against subsequent H. bakeri infection and generates antibodies that block exWAGO uptake into cells. Finally, we show that properties of exWAGO are conserved across Clade V nematodes that infect humans and livestock. Together this work expands the context in which Argonautes function and illuminates an RNA-binding protein as a vaccine target for parasitic nematodes.

Schistosoma heamatobium tetraspanins TSP-2 and TSP-6 induce Dendritic Cells maturation, cytokine production and T helper cells differentiation in vitro

Urogenital schistosomiasis caused by Schistosoma haematobium is a major cause of disability in endemic areas. Despite its socio-economic burden, no vaccine exists and the parasite's immunobiology remains underexplored. Genome annotation has revealed over 40 different genes encoding tetraspanins, transmembrane proteins with known immunomodulatory properties in other plathelminthes. This study investigated the role of Sh-TSP-2, Sh-TSP-6 and Sh-TSP-23, which are expressed in the parasite's tegument and extracellular vesicles (EVs). Immature dendritic cells (DCs) from unexposed healthy donors were stimulated with these proteins to evaluate maturation maker expression and cytokine production. Also, pre-activated T CD4+ cells were stimulated with the DCs supernatant to assess cytokine gene expression. Sh-TSP-2 and Sh-TSP-6 induced maturation markers and cytokine production in DCs: Sh-TSP-2 increased CD80 and CD83 levels and the concentration of both pro-inflammatory (IL-6, TNF) and regulatory (IL-10) cytokines, while Sh-TSP-6 increased the production of IL-6. Moreover, supernatants from Sh-TSP-2 stimulated DCs induced the expression of Th1 (IFNɣ) and regulatory (IL-10) cytokines in CD4+ T cells, while Sh-TSP-6 induced Th2 (IL-4, IL-13) cytokine expression. These results provide evidence that S. haematobium tetraspanins modulate the response of human DCs and CD4+ T cells in vitro, and support Sh-TSP-2 as a promising vaccine candidate.

The association between Clonorchis sinensis seropositivity and hepatocellular carcinoma in an endemic area: a study in Guangxi, China

BACKGROUND

Chronic infection with Clonorchis sinensis (C.sinensis) has been associated swith the development of intrahepatic cholangiocarcinoma (ICC); however, the relationship between C.sinensis and hepatocellular carcinoma (HCC) remains uncertain.

METHODS

This study examined 120 patients with liver cancer in the clonorchiasis endemic area of Hengzhou, Guangxi, China. The type of cancer, the differentiation grade according to Edmondson Steiner's classification, and the pathological characteristics of HCC were determined through postoperative tissue biopsy. C.sinensis infection was detected by measuring serum specific IgG antibody, and hepatitis B virus (HBV) infection was determined by detecting serum HBsAg and HBV DNA in HCC tissues. The C.sinensis infection rates in control groups were drawn from the local general population based on previous surveys. The association between C.sinensis infection and HCC was analyzed by comparing the differences in C.sinensis infection rates between the two groups.

RESULTS

Of the patients evaluated, 98 (81.7%) had HCC, 21 (17.5%) had ICC, and 1 (0.8%) had comorbidity of HCC/ICC. Among the HCC patients, 24 (24.5%) were solely infected with HBV, 71 (72.4%) were C. sinensis seropositive, and 3 (3.1%) showed no evidence of infection. C. sinensis seropositive rates in HCC patients are much higher than in general outpatient and non-liver cancer inpatients (χ2 = 141.92, p < 0.001), as well as in the local residents (χ2 = 82.61/21.38, p < 0.001). There were no significant differences in the pathological type, differentiation grade, and lesion composition between the tumor associated with C.sinensis/HBV mono- and co-infection (p > 0.05). Among the patients with C.sinensis-related HCC, 8 (8.2%) were solely C.sinensis seropositive, while 63 (64.3%) were co-infected with HBV. Infection with C. sinensis and HBV has a significant impact on the pathological types of liver cancer (χ2 = 22.86, p < 0.001).

CONCLUSIONS

These findings indicate that HCC still accounts for the majority of liver cancer in this region. In addition to being most commonly related with HBV infection, HCC may also be related to C. sinensis infection. Co-infection of C. sinensis and HBV may enhance the development of HCC in this area.

CLINICAL TRIAL

Not applicable.

Profiling host- and parasite-derived miRNAs associated with Strongylus vulgaris infection in horses

The equine bloodworm, Strongylus vulgaris, is a common and highly pathogenic parasite in horses due to its migratory life cycle involving the intestinal arteries. Current diagnostic techniques cannot detect the prepatent migrating stages of S. vulgaris, highlighting the need for new biomarkers. Parasites release microRNAs (miRNAs) into their environment, which could potentially be detectable in host blood samples. Additionally, host miRNA expression patterns may change in response to infection. This study aimed to identify miRNAs associated with S. vulgaris infection by profiling the horse's miRNA response in the larval predilection site, the Cranial Mesenteric Artery (CMA) and examining the circulating parasite and horse-derived miRNAs in plasma of S. vulgaris-infected horses. Plasma samples were collected from 27 horses naturally infected with S. vulgaris and 28 uninfected horses. Arterial tissue samples from the CMA and Aorta were collected from a subset (n = 12) of the infected horses. Small RNA sequencing (small RNAseq) of a subset of the plasma samples (n = 12) identified miRNAs of interest, followed by quantitative real-time PCR (qPCR) evaluation of selected miRNAs in plasma from a larger cohort of horses. Small RNAseq detected 138 parasite-derived and 533 horse-derived miRNAs in the plasma samples. No difference in parasite-derived miRNA abundance was found between the infected and uninfected horses, but 140 horse-derived miRNAs were significantly differentially abundant between the two groups. When evaluated by qPCR, none of the selected parasite-derived miRNAs were detectable in plasma, but seven horse-derived miRNAs were confirmed differentially abundant in plasma between the two groups. Seven horse-derived miRNAs were differentially expressed in CMA tissue affected by migrating S. vulgaris compared with unaffected aortic tissue, with Eca-Mir-223-3p (Log2FC: 4.74) and Eca-Mir-140-3p (Log2FC: -3.64) being most differentially expressed. A receiver operating characteristic curve analysis suggested that Eca-Mir-486-5p and Eca-Mir-140-3p had the best diagnostic performance for distinguishing between infected and uninfected horses, with areas under the curve (AUC) of 0.78 and 0.77, respectively. Notably, Eca-Mir-140-3p was associated with age, and correcting for interaction with age increased the AUC to 0.96. In conclusion, several horse-derived miRNAs were associated with S. vulgaris infection and could differentiate between infected and uninfected horses based on their plasma abundance. However, the levels of these miRNAs were influenced by other factors (i.e age, breed), complicating their use as biomarkers. Parasite-derived miRNA abundance did not differ between S. vulgaris infected horses and those infected with other parasites using small RNAseq and were below detection limits of qPCR.

Helminth extracellular vesicles co-opt host monocytes to drive T cell anergy

Parasitic helminths secrete extracellular vesicles (EVs) into their host tissues to modulate immune responses, but the underlying mechanisms are poorly understood. We demonstrate that Ascaris EVs are efficiently internalised by monocytes in human peripheral blood mononuclear cells and increase the percentage of classical monocytes. Furthermore, EV treatment of monocytes induced a novel anti-inflammatory phenotype characterised by CD14+, CD16-, CC chemokine receptor 2 (CCR2-) and programmed death-ligand 1 (PD-L1)+ cells. In addition, Ascaris EVs induced T cell anergy in a monocyte-dependent mechanism. Targeting professional phagocytes to induce both direct and indirect pathways of immune modulation presents a highly novel and efficient mechanism of EV-mediated host-parasite communication. Intra-peritoneal administration of EVs induced protection against gut inflammation in the dextran sodium sulphate model of colitis in mice. Ascaris EVs were shown to affect circulating immune cells and protect against gut inflammation; this highlights their potential as a subject for further investigation in inflammatory conditions driven by dysregulated immune responses. However, their clinical translation would require further studies and careful consideration of ethical implications.

Exploring microRNA-Mediated Immune Responses to Soil-Transmitted Helminth and Herpes Simplex Virus Type 2 Co-Infections

Over the last two decades, the field of microRNA (miRNA) research has grown significantly. MiRNAs are a class of short, single-stranded, non-coding RNAs that regulate gene expression post-transcriptionally. Thereby, miRNAs regulate various essential biological processes including immunity. Dysregulated miRNAs are associated with various infectious and non-infectious diseases. Recently co-infection with soil-transmitted helminths (STHs) and herpes simplex virus type 2 (HSV-2) has become a focus of study. Both pathogens can profoundly influence host immunity, particularly in under-resourced and co-endemic regions. It is well known that STHs induce immunomodulatory responses that have bystander effects on unrelated conditions. Typically, STHs induce T-helper 2 (Th2) and immunomodulatory responses, which may dampen the proinflammatory T-helper 1 (Th1) immune responses triggered by HSV-2. However, the extent to which STH co-infection influences the host immune response to HSV-2 is not well understood. Moreover, little is known about how miRNAs shape the immune response to STH/HSV-2 co-infection. In this article, we explore the potential influence that STH co-infection may have on host immunity to HSV-2. Because STH and HSV-2 infections are widespread and disproportionately affect vulnerable and impoverished countries, it is important to consider how STHs may impact HSV-2 immunity. Specifically, we explore how miRNAs contribute to both helminth and HSV-2 infections and discuss how miRNAs may mediate STH/HSV-2 co-infections. Insight into miRNA-mediated immune responses may further improve our understanding of the potential impact of STH/HSV-2 co-infections.

Infection by the Lungworm Rhabdias pseudosphaerocephala Affects the Expression of Immune-Related microRNAs by Its Co-Evolved Host, the Cane Toad Rhinella marina

Parasites may suppress the immune function of infected hosts using microRNAs (miRNAs) to prevent protein production. Nonetheless, little is known about the diversity of miRNAs and their mode(s) of action. In this study, we investigated the effects of infection by a parasitic lungworm (Rhabdias pseudosphaerocephala) on miRNA and mRNA expression of its host, the invasive cane toad (Rhinella marina). To investigate the cane toad's innate and adaptive immune response to this parasite, we compared miRNA and mRNA expression in naïve toads that had never been infected by lungworms to toads that were infected with lungworms for the first time in their lives, and toads that were infected the second time in their lives (i.e., had two consecutive infections). In total, we identified 101 known miRNAs and 86 potential novel miRNAs. Compared to uninfected and single-infection toads, multiple-infection animals drastically downregulated three miRNAs. These miRNAs were associated with gene pathways related to the immune response, potentially reflecting the immunosuppression of cane toads by their parasites. Infected hosts did not respond with substantially differential mRNA transcription; only one gene was differentially expressed between control and single-infection hosts. Our study suggests that miRNA may play an important role in mediating host-parasite interactions in a system in which an ongoing range expansion by the host has generated substantial divergence in host-parasite interactions.

Unraveling the microRNAs Involved in Fasciolosis: Master Regulators of the Host-Parasite Crosstalk

Fasciolosis is a neglected tropical disease caused by helminth parasites of the genus Fasciola spp., including Fasciola hepatica (F. hepatica) and Fasciola gigantica (F. gigantica), being a major zoonotic problem of human and animal health. Its control with antihelminthics is becoming ineffective due to the increase in parasite resistance. Developing new therapeutic protocols is crucial to a deeper knowledge of the molecular bases in the host-parasite interactions. The high-throughput omics technologies have dramatically provided unprecedented insights into the complexity of the molecular host-parasite crosstalk. MicroRNAs (miRNAs) are key players as critical regulators in numerous biological processes, modifying the gene expression of cells by degradation of messenger RNA (mRNA), regulating transcription and translation functions, protein positioning, cell cycle integrity, differentiation and apoptosis. The large-scale exploration of miRNAs, including the miRNome, has offered great scientific knowledge of steps in fasciolosis, further scrutinizing the pathogenesis, the growth and development of their strains and their interaction with the host for the survival of the different parasite stages. This review compiles the updated knowledge related to miRNAs involved in fasciolosis and the generated miRNome, highlighting the importance of these key molecules in the host-parasite interactions and the pathogenesis of Fasciola spp. directing towards the development of new biotherapeutic protocols for the control of fasciolosis.

The Nature and Nurture of Extracellular Vesicle-Mediated Signaling

In the last decade, it has become clear that extracellular vesicles (EVs) are a ubiquitous component of living systems. These small membrane-enclosed particles can confer diverse functions to the cells that release, capture, or coexist with them in an environment. We use examples across living systems to produce a conceptual framework that classifies three modes by which EVs exert functions: (a) EV release that serves a function for producing cells, (b) EV modification of the extracellular environment, and (c) EV interactions with, and alteration of, receiving cells. We provide an overview of the inherent properties of EVs (i.e., their nature) as well as factors in the environment and receiving cell (i.e., nurture) that determine whether transmission of EV cargo leads to functional cellular responses. This review broadens the context for ruminating on EV functions and highlights the emergent properties of EVs that define their role in biology and will shape their applications in medicine.

Extracellular vesicles biogenesis and uptake concepts: A comprehensive guide to studying host-pathogen communication

The study of host-pathogen interactions has increased considerably in recent decades. This intercellular communication has been mediated by extracellular vesicles (EVs) that play an important role during the interaction. EVs are particles of lipid bilayer and described in different types of cells, eukaryotic or prokaryotic. Depending on their biogenesis they are described as exosomes (derived from multivesicular bodies) and microvesicles (derived from the plasma membrane). The EVs carry biomolecules, including nucleic acids, lipids, and proteins that can be released or internalized by other cells in different pathways (endocytosis, macropinocytosis, phagocytosis, or membrane fusion) in the process described as uptake. The balance between biogenesis and uptake of EVs could modify physiological and pathophysiological processes of the cell. This review is focusing on the dynamic roles of release and capture of EVs during host-pathogen interaction. We also do a critical analysis of methodologies for obtaining and analyzing EVs. Finally, we draw attention to critical points to be considered in EV biogenesis and uptake studies.

Among-Population Differentiation in the Tapeworm Proteome through Prediction of Excretory/Secretory and Transmembrane Proteins in Schistocephalus solidus

Background

Parasites secrete and excrete a variety of molecules evolve to help establish and sustain infections within hosts. Parasite adaptation to their host may lead to between-population divergence in these excretory and secretory products (ESPs), but few studies have tested for intraspecific variation in helminth proteomes.

Methods

Schistocephalus solidus is a cestode that parasitizes three spined stickleback, Gasterosteus aculeatus . We used an ultra-performance liquid chromatography-mass spectrometry protocol to characterize the ESP and whole-body proteome of S. solidus. Specifically, we characterized the proteome of S. solidus at the plerocercoid stage from wild caught stickleback from three lakes on Vancouver Island (British Columbia, Canada) and one lake in Alaska (United States). We tested for differences in proteome composition among the four populations and specifically between ESPs and body tissue.

Results

Overall, we identified 1362 proteins in the total proteome of S. solidus, with 542 of the 1362 proteins detected exclusively in the ESPs. Of the ESP proteins, we found signaling peptides and transmembrane proteins that were previously not detected or characterized in S. solidus. We also found protein spectrum counts greatly varied between all lake populations.

Conclusions

These population-level differences were observed in both ESP and tissue types. Our study suggests that S. solidus can excrete and secrete a wide range of proteins which are distinct among populations. These differences might reflect plastic responses to host genotype differences, or evolved adaptations by Schistocephalus to different local host populations.

Roles of helminth extracellular vesicle-derived let-7 in host-parasite crosstalk

Helminth infections are a major public health problem as they can cause long-term chronic infections in their hosts for which there is no effective vaccine. During the long-term interaction between helminths and their hosts, helminth-derived extracellular vesicles (EVs) can participate in host immunomodulatory processes by secreting bioactive molecules (BMAs). Growing data suggests that microRNAs (miRNAs) in helminth EVs have a significant impact on the host's immune system. The let-7 family is highly conserved among helminth EVs and highly homologous in the host, and its function in host-parasite crosstalk may reflect active selection for compatibility with the host miRNA machinery. In-depth studies targeting this aspect may better elucidate the mechanism of parasite-host interactions. Hence, this review summarizes the current studies on the cross-species involvement of helminth EV-derived let-7 in host immune regulation and discusses the barriers to related research and potential applications of helminth EVs.

Novel insights into the role of immunomodulatory extracellular vesicles in the pathogenesis of liver fibrosis

Liver fibrosis, a chronic and long-term disease, can develop into hepatocellular carcinoma (HCC) and ultimately lead to liver failure. Early diagnosis and effective treatment still face significant challenges. Liver inflammation leads to liver fibrosis through continuous activation of hepatic stellate cells (HSCs) and the accumulation of immune cells. Intracellular communication among various immune cells is important for mediating the inflammatory response during fibrogenesis. Extracellular vesicles (EVs), which are lipid bilayer membrane-enclosed particles naturally secreted by cells, make great contributions to cell-cell communication and the transport of bioactive molecules. Nearly all the cells that participate in liver fibrosis release EVs loaded with lipids, proteins, and nucleic acids. EVs from hepatocytes, immune cells and stem cells are involved in mediating the inflammatory microenvironment of liver fibrosis. Recently, an increasing number of extracellular vesicle-based clinical applications have emerged, providing promising cell-free diagnostic and therapeutic tools for liver fibrosis because of their crucial role in immunomodulation during pathogenesis. The advantages of extracellular vesicle-based therapies include stability, biocompatibility, low cytotoxicity, and minimal immunogenicity, which highlight their great potential for drug delivery and specific treatments for liver fibrosis. In this review, we summarize the complex biological functions of EVs in the inflammatory response in the pathogenesis of liver fibrosis and evaluate the potential of EVs in the diagnosis and treatment of liver fibrosis.

Immunization with the glutathione S-transferase Sj26GST with Chi-CpG NP against Schistosoma japonicum in mice

Schistosomiasis caused by Schistosoma japonicum (S. japonicum) is a major public health problem in the Philippines, China and Indonesia. In this study, the immunopotentiator CpG-ODN was encapsulated within chitosan nanoparticles (Chi NPs) to create a combination adjuvant (Chi-CpG NP). This approach was employed to enhance the immunogenicity of 26 kDa glutathione S-transferase (Sj26GST) from S. japonicum through intranasal immunization. The results demonstrated higher levels of specific anti-Sj26GST antibodies and Sj26GST-specific splenocyte proliferation compared to mice that were immunized with Sj26GST + Chi-CpG NP. Cytokine analysis of splenocytes revealed that the Sj26GST + Chi-CpG NP induced a slight Th1-biased immune response, with increased production of IFN-γ by CD4+ T-cells in the spleen. Subsequently, mice were intradermally inoculated with 1 × 107 organisms in the Coeliac cavity. The bacterial organ burden detected in the liver of immunized mice suggested that Sj26GST + Chi-CpG NP enhances protective immunity to inhibit S. japonicum colonization. Therefore, Sj26GST + Chi-CpG NP vaccination enhances Sj26GST-specific immunogenicity and provides protection against S. japonicum.

Helminth-derived molecules: pathogenic and pharmacopeial roles

Parasitic helminths, taxonomically comprising trematodes, cestodes, and nematodes, are multicellular invertebrates widely disseminated in nature and have afflicted people continuously for a long time. Helminths play potent roles in the host through generating a variety of novel molecules, including some excretory/secretory products and others that are involved in intracellular material exchange and information transfer as well as the initiation or stimulation of immune and metabolic activation. The helminth-derived molecules have developed powerful and diverse immunosuppressive effects to achieve immune evasion for parasite survival and establish chronic infections. However, they also improve autoimmune and allergic inflammatory responses and promote metabolic homeostasis by promoting metabolic reprogramming of various immune functions, and then inducing alternatively activated macrophages, T helper 2 cells, and regulatory T cells-mediated immune responses. Therefore, a deeper exploration of the immunopathogenic mechanism and immune regulatory mechanisms of helminth-derived molecules exerted in the host is crucial for understanding host-helminth interactions as well as the development of therapeutic drugs for infectious or non-infectious diseases. In this review, we focus on the properties of helminth-derived molecules to give an overview of the most recent scientific knowledge about their pathogenic and pharmacopeial roles in immune-metabolic homeostasis.

Exploring extracellular vesicles in zoonotic helminth biology: implications for diagnosis, therapeutic and delivery

Extracellular vesicles (EVs) have emerged as key intercellular communication and pathogenesis mediators. Parasitic organisms' helminths, cause widespread infections with significant health impacts worldwide. Recent research has shed light on the role of EVs in the lifecycle, immune evasion, and disease progression of these parasitic organisms. These tiny membrane-bound organelles including microvesicles and exosomes, facilitate the transfer of proteins, lipids, mRNAs, and microRNAs between cells. EVs have been isolated from various bodily fluids, offering a potential diagnostic and therapeutic avenue for combating infectious agents. According to recent research, EVs from helminths hold great promise in the diagnosis of parasitic infections due to their specificity, early detection capabilities, accessibility, and the potential for staging and monitoring infections, promote intercellular communication, and are a viable therapeutic tool for the treatment of infectious agents. Exploring host-parasite interactions has identified promising new targets for diagnostic, therapy, and vaccine development against helminths. This literature review delves into EVS's origin, nature, biogenesis, and composition in these parasitic organisms. It also highlights the proteins and miRNAs involved in EV release, providing a comprehensive summary of the latest findings on the significance of EVs in the biology of helminths, promising targets for therapeutic and diagnostic biomarkers.

Identification and functional analysis of mitogenic miRNA of the carcinogenic liver fluke Opisthorchis viverrini

Opisthorchis viverrini is a pathogenic liver fluke that is known to cause cholangiocarcinoma in chronic infections. The underlying mechanism for this carcinogenesis is believed to be multifactorial, with parasite-derived excretory-secretory (ES) products potentially playing major roles. A recent study on these ES products has identified microRNAs (miRNA) that originate from O. viverrini but their influence on carcinogenesis remains understudied. Hence, we aimed to investigate the role of these miRNAs in the carcinogenesis of O. viverrini-associated cholangiocarcinoma. The mature miRNA sequences were retrieved from published data. Bioinformatics analysis was employed to identify miRNA targets and to identify potentially mitogenic miRNAs. An in vitro study was conducted to test the effects of miRNA on the bile duct epithelial cell lines. The miRNA target prediction analysis revealed that Ov_miRNA_EV_36/ovi-miR-3479a targets cancer-associated pathways. Hence, it was selected and used to assess its effect on the cell proliferation rate of H69 and MMNK-1 cholangiocyte cell lines. The results showed that Ov_miRNA_EV_36/ovi-miR-3479a induced significant cell proliferation in both cell lines when compared to negative controls. These results indicate that Ov_miRNA_EV_36/ovi-miR-3479a may play an essential role in the carcinogenesis of O. viverrini and therefore warrant further investigations.

Induction of hepatic fibrosis in mice with schistosomiasis by extracellular microRNA-30 derived from Schistosoma japonicum eggs

Background

Schistosomiasis is a zoonotic parasitic disorder induced by the infestation of schistosomes, a genus of trematodes. MicroRNAs (miRNAs) in egg-derived exosomes are crucial for modulating the host's immune responses and orchestrating the pathophysiological mechanisms. Although the exosomes secreted by S. japonicum contain abundant miRNAs, the specific roles of these miRNAs in the pathogenesis of schistosomiasis-induced hepatic fibrosis are yet to be comprehensively elucidated. The egg exosomes of S. japonicum secrete miRNA-30, a novel miRNA.

Methods

In vitro, the effect of miRNA-30 was evaluated by transfecting HSCs with miRNA mimics. The target gene biosignature for miRNA-30 was predicted using the miRDB software. The effect of miRNA-30 in hepatic fibrosis was evaluated by either elevating its expression in healthy mice or by inhibiting its activity in infected mice by administration of recombinant adeno-associated virus serotype eight vectors expressing miRNA-30 or miRNA sponges.

Results

This novel miRNA can activate hepatic stellate cells (HSCs), the prinary effector cells of hepatic fibrosis, in vitro, i.e., it significantly increases the fibrogenic factors Col1(α1), Col3(α1), and α-SMA at both mRNA and protein levels. In addition, miRNA-30 may activate HSCs by targeting the host RORA gene. In addition, in vivo experiments were conducted by administering a recombinant adeno-associated viral vector to modulate the expression levels of miRNA-30. The overexpression of miRNA-30 in healthy mice significantly elevated the expression of Col1(α1), Col3(α1), and α-SMA at both the transcriptomic and proteomic scales. This overexpression was coupled with a pronounced augmentation in the hepatic hydroxyproline content. Conversely, the in vivo silencing of miRNA-30 in infected mice induced a considerable reduction in the size of hepatic granulomas and areas of collagen deposition. Hence, in vivo, modulation of miRNA-30 expression may play a pivotal role in ameliorating the severity of hepatic fibrosis in mice afflicted with S. japonica.

Conclusions

The study results suggest that miRNA-30 may augment schistosomiasis-induced hepatic fibrosis through a probable interaction with the host RORA. Our study may improve the current theoretical framework regarding cross-species regulation by miRNAs of hepatic fibrosis in schistosomiasis.

Giardia intestinalis extracellular vesicles induce changes in gene expression in human intestinal epithelial cells in vitro

Giardiasis is a common waterborne zoonotic disease caused by Giardia intestinalis. Upon infection, Giardia releases excretory and secretory products (ESPs) including secreted proteins (SPs) and extracellular vesicles (EVs). Although the interplay between ESPs and intestinal epithelial cells (IECs) has been previously described, the functions of EVs in these interactions and their differences from those of SPs require further exploration. In the present study, EVs and EV-depleted SPs were isolated from Giardia ESPs. Proteomic analyses of isolated SPs and EVs showed 146 and 91 proteins, respectively. Certain unique and enriched proteins have been identified in SPs and EVs. Transcriptome analysis of Caco-2 cells exposed to EVs showed 96 differentially expressed genes (DEGs), with 56 upregulated and 40 downregulated genes. Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and Gene Set Enrichment Analysis (GSEA) indicated that Caco-2 genes related to metabolic processes, the HIF-1 signaling pathway, and the cAMP signaling pathway were affected. This study provides new insights into host-parasite interactions, highlighting the potential significance of EVs on IECs during infections.

Trichomonas vaginalis extracellular vesicles up-regulate and directly transfer adherence factors promoting host cell colonization

Trichomonas vaginalis, a common sexually transmitted parasite that colonizes the human urogenital tract, secretes extracellular vesicles (TvEVs) that are taken up by human cells and are speculated to be taken up by parasites as well. While the crosstalk between TvEVs and human cells has led to insight into host:parasite interactions, roles for TvEVs in infection have largely been one-sided, with little known about the effect of TvEV uptake by T. vaginalis. Approximately 11% of infections are found to be coinfections of multiple T. vaginalis strains. Clinical isolates often differ in their adherence to and cytolysis of host cells, underscoring the importance of understanding the effects of TvEV uptake within the parasite population. To address this question, our lab tested the ability of a less adherent strain of T. vaginalis, G3, to take up fluorescently labeled TvEVs derived from both itself (G3-EVs) and TvEVs from a more adherent strain of the parasite (B7RC2-EVs). Here, we showed that TvEVs generated from the more adherent strain are internalized more efficiently compared to the less adherent strain. Additionally, preincubation of G3 parasites with B7RC2-EVs increases parasite aggregation and adherence to host cells. Transcriptomics revealed that TvEVs up-regulate expression of predicted parasite membrane proteins and identified an adherence factor, heteropolysaccharide binding protein (HPB2). Finally, using comparative proteomics and superresolution microscopy, we demonstrated direct transfer of an adherence factor, cadherin-like protein, from TvEVs to the recipient parasite's surface. This work identifies TvEVs as a mediator of parasite:parasite communication that may impact pathogenesis during mixed infections.

Schistosoma japonicum extracellular vesicle proteins serve as effective biomarkers for diagnosing parasite infection

Schistosoma species are the causative agent of schistosomiasis and shows worldwide distribution. There is a great need to develop a sensitive diagnostic approach for controlling the disease. Previously, we identified large numbers of Extracellular Vesicle (EV) proteins from Schistosoma japonicum (S. japonicum), but rarely these proteins have been evaluated for their diagnostic potential. In the present study, we performed bioinformatic analyses of S. japonicum identified EV-associated proteins from the previous study and then identified Schistosoma-specific proteins with potentially secreted capability. Among them, we selected SJCHGC02838 protein, SJCHGC05593 protein, SJCHGC05668 protein and a hypothetical protein (SJHYP) to evaluate their diagnostic potential for detecting S. japonicum infection. First, we determined the expression of these four proteins at the transcript levels using qRT-PCR and revealed that all these genes showed higher expression in adult stage. Then, we cloned the full-length cDNA for each protein into a prokaryotic expression vector and successfully generated the recombinant proteins. Upon the purification of recombinant proteins, we developed an indirect ELISA method to evaluate the diagnostic potential of these purified recombinant proteins. The results showed high sensitivity for detecting Schistosoma infection. Additionally, these proteins also displayed a good potential for detecting Schistosoma infection, especially SJCHGC05668 protein at an early stage. The diagnostic potentials of these recombinant proteins were further evaluated by Western blot and comparatively analyzed by our previously developed cfDNA methods.

Long Non-Coding RNA Levels Are Modulated in Schistosoma mansoni following In Vivo Praziquantel Exposure

Schistosomiasis is a disease caused by trematodes of the genus Schistosoma that affects over 200 million people worldwide. For decades, praziquantel (PZQ) has been the only available drug to treat the disease. Despite recent discoveries that identified a transient receptor ion channel as the target of PZQ, schistosome response to this drug remains incompletely understood, since effectiveness relies on other factors that may trigger a complex regulation of parasite gene expression. Long non-coding RNAs (lncRNAs) are transcripts longer than 200 nucleotides with low or no protein-coding potential that play important roles in S. mansoni homeostasis, reproduction, and fertility. Here, we show that in vivo PZQ treatment modulates lncRNA levels in S. mansoni. We re-analyzed public RNA-Seq data from mature and immature S. mansoni worms treated in vivo with PZQ and detected hundreds of lncRNAs differentially expressed following drug exposure, many of which are shared among mature and immature worms. Through RT-qPCR, seven out of ten selected lncRNAs were validated as differentially expressed; interestingly, we show that these lncRNAs are not adult worm stage-specific and are co-expressed with PZQ-modulated protein-coding genes. By demonstrating that parasite lncRNA expression levels alter in response to PZQ, this study unravels an important step toward elucidating the complex mechanisms of S. mansoni response to PZQ.

An inside out journey: biogenesis, ultrastructure and proteomic characterisation of the ectoparasitic flatworm Sparicotyle chrysophrii extracellular vesicles

BACKGROUND

Helminth extracellular vesicles (EVs) are known to have a three-way communication function among parasitic helminths, their host and the host-associated microbiota. They are considered biological containers that may carry virulence factors, being therefore appealing as therapeutic and prophylactic target candidates. This study aims to describe and characterise EVs secreted by Sparicotyle chrysophrii (Polyopisthocotyla: Microcotylidae), a blood-feeding gill parasite of gilthead seabream (Sparus aurata), causing significant economic losses in Mediterranean aquaculture.

METHODS

To identify proteins involved in extracellular vesicle biogenesis, genomic datasets from S. chrysophrii were mined in silico using known protein sequences from Clonorchis spp., Echinococcus spp., Fasciola spp., Fasciolopsis spp., Opisthorchis spp., Paragonimus spp. and Schistosoma spp. The location and ultrastructure of EVs were visualised by transmission electron microscopy after fixing adult S. chrysophrii specimens by high-pressure freezing and freeze substitution. EVs were isolated and purified from adult S. chrysophrii (n = 200) using a newly developed ultracentrifugation-size-exclusion chromatography protocol for Polyopisthocotyla, and EVs were characterised via nanoparticle tracking analysis and tandem mass spectrometry.

RESULTS

Fifty-nine proteins involved in EV biogenesis were identified in S. chrysophrii, and EVs compatible with ectosomes were observed in the syncytial layer of the haptoral region lining the clamps. The isolated and purified nanoparticles had a mean size of 251.8 nm and yielded 1.71 × 108 particles · mL-1. The protein composition analysis identified proteins related to peptide hydrolases, GTPases, EF-hand domain proteins, aerobic energy metabolism, anticoagulant/lipid-binding, haem detoxification, iron transport, EV biogenesis-related, vesicle-trafficking and other cytoskeletal-related proteins. Several identified proteins, such as leucyl and alanyl aminopeptidases, calpain, ferritin, dynein light chain, 14-3-3, heat shock protein 70, annexin, tubulin, glutathione S-transferase, superoxide dismutase, enolase and fructose-bisphosphate aldolase, have already been proposed as target candidates for therapeutic or prophylactic purposes.

CONCLUSIONS

We have unambiguously demonstrated for the first time to our knowledge the secretion of EVs by an ectoparasitic flatworm, inferring their biogenesis machinery at a genomic and transcriptomic level, and by identifying their location and protein composition. The identification of multiple therapeutic targets among EVs' protein repertoire provides opportunities for target-based drug discovery and vaccine development for the first time in Polyopisthocotyla (sensu Monogenea), and in a fish-ectoparasite model.

Sja-let-7 suppresses the development of liver fibrosis via Schistosoma japonicum extracellular vesicles

Schistosomiasis is a fatal zoonotic parasitic disease that also threatens human health. The main pathological features of schistosomiasis are granulomatous inflammation and subsequent liver fibrosis, which is a complex, chronic, and progressive disease. Extracellular vesicles (EVs) derived from schistosome eggs are broadly involved in host-parasite communication and act as important contributors to schistosome-induced liver fibrosis. However, it remains unclear whether substances secreted by the EVs of Schistosoma japonicum, a long-term parasitic "partner" in the hepatic portal vein of the host, also participate in liver fibrosis. Here, we report that EVs derived from S. japonicum worms attenuated liver fibrosis by delivering sja-let-7 into hepatic stellate cells (HSCs). Mechanistically, activation of HSCs was reduced by targeting collagen type I alpha 2 chain (Col1α2) and downregulation of the TGF-β/Smad signaling pathway both in vivo and in vitro. Overall, these results contribute to further understanding of the molecular mechanisms underlying host-parasite interactions and identified the sja-let-7/Col1α2/TGF-β/Smad axis as a potential target for treatment of schistosomiasis-related liver fibrosis.

The knowns and unknowns of helminth-host miRNA cross-kingdom communication

MicroRNAs (miRNAs) are small noncoding RNAs that oversee gene modulation. They are integral to cellular functions and can migrate between species, leading to cross-kingdom gene suppression. Recent breakthroughs in helminth genome studies have sparked curiosity about helminth RNA regulators and their ability to regulate genes across species. Growing data indicate that helminth miRNAs have a significant impact on the host's immune system. Specific miRNAs from helminth parasites can merge with the host's miRNA system, implying that parasites could exploit their host's regulatory machinery and function. This review highlights the role of cross-kingdom helminth-derived miRNAs in the interplay between host and parasite, exploring potential routes for their uptake, processing, and consequences in host interaction.

Non-coding RNA in the gut of the blood-feeding parasitic worm, Haemonchus contortus

The intestine of Haemonchus contortus is an essential tissue that has been indicated to be a major target for the prevention of haemonchosis caused by this parasitic nematode of small ruminants. Biological peculiarities of the intestine warrant in-depth exploitation, which can be leveraged for future disease control efforts. Here, we determined the intestinal ncRNA (lncRNA, circRNA and miRNA) atlas using whole-transcriptome sequencing and bioinformatics approaches. In total, 4846 novel lncRNA, 982 circRNA, 96 miRNA (65 known and 31 novel) and 8821 mRNA were identified from the H. contortus intestine. The features of lncRNA, circRNA and miRNA were fully characterized. Comparison of miRNA from the intestines and extracellular vesicles supported the speculation that the miRNA from the latter were of intestinal origin in H. contortus. Further function analysis suggests that the cis-lncRNA targeted genes were involved in protein binding, intracellular anatomical structure, organelle and cellular process, whereas the circRNA parental genes were mainly enriched in molecular function categories, such as ribonucleotide binding, nucleotide binding, ATP binding and carbohydrate derivative binding. The miRNA target genes were related to the cellular process, cellular response to stimulus, cellular protein modification process and signal transduction. Moreover, competing endogenous RNA network analysis revealed that the majority of lncRNA, circRNA and mRNA only have one or two binding sites with specific miRNA. Lastly, randomly selected circRNA, lncRNA and miRNA were verified successfully using RT-PCR. Collectively, these data provide the most comprehensive compilation of intestinal transcripts and their functions, and it will be helpful to decipher the biological and molecular complexity of the intestine and lay the foundation for further functional research.

Both host and parasite non-coding RNAs co-ordinate the regulation of macrophage gene expression to reduce pro-inflammatory immune responses and promote tissue repair pathways during infection with fasciola hepatica

Parasitic worms (helminths) establish chronic infection within mammalian hosts by strategically regulating their host's immune responses. Deciphering the mechanisms by which host non-coding RNAs (ncRNA) co-ordinate the activation and regulation of immune cells is essential to understanding host immunity and immune-related pathology. It is also important to comprehend how pathogens secrete specific ncRNAs to manipulate gene expression of host immune cells and influence their response to infection. To investigate the contribution of both host and helminth derived ncRNAs to the activation and/or regulation of innate immune responses during a parasite infection, we examined ncRNA expression in the peritoneal macrophages from mice infected with Fasciola hepatica. We discovered the presence of several parasitic-derived miRNAs within host macrophages at 6 hrs and 18 hrs post infection. Target prediction analysis showed that these Fasciola miRNAs regulate host genes associated with the activation of host pro-inflammatory macrophages. Concomitantly, there was a distinct shift in host ncRNA expression, which was significant at 5 days post-infection. Prediction analysis suggested that these host ncRNAs target a different cohort of host genes compared to the parasite miRNAs, although the functional outcome was predicted to be similar i.e. reduced pro-inflammatory response and the promotion of a reparative/tolerant phenotype. Taken together, these observations uncover the interplay between host and parasitic ncRNAs and reveal a complementary regulation of the immune response that allows the parasite to evade immune detection and promote tissue repair for the host. These findings will provide a new understanding of the molecular interaction between parasites and host.

RNA-containing extracellular vesicles in infection

Extracellular vesicles (EVs) are membrane-bound particles released by cells that play vital roles in intercellular communication by transporting diverse biologically active molecules, including RNA molecules, including mRNA, miRNA, lncRNA, and other regulatory RNAs. These RNA types are protected within the lipid bilayer of EVs, ensuring their stability and enabling long-distance cellular interactions. Notably, EVs play roles in infection, where pathogens and host cells use EV-mediated RNA transfer to influence immune responses and disease outcomes. For example, bacterial EVs play a crucial role in infection by modulating host immune responses and facilitating pathogen invasion. This review explores the complex interactions between EV-associated RNA and host-pathogen dynamics in bacteria, parasites, and fungi, aiming to uncover molecular mechanisms in infectious diseases and potential therapeutic targets.

MicroRNAs in infectious diseases: potential diagnostic biomarkers and therapeutic targets

MicroRNAs (miRNAs) are conserved, short, non-coding RNAs that play a crucial role in the post-transcriptional regulation of gene expression. They have been implicated in the pathogenesis of cancer and neurological, cardiovascular, and autoimmune diseases. Several recent studies have suggested that miRNAs are key players in regulating the differentiation, maturation, and activation of immune cells, thereby influencing the host immune response to infection. The resultant upregulation or downregulation of miRNAs from infection influences the protein expression of genes responsible for the immune response and can determine the risk of disease progression. Recently, miRNAs have been explored as diagnostic biomarkers and therapeutic targets in various infectious diseases. This review summarizes our current understanding of the role of miRNAs during viral, fungal, bacterial, and parasitic infections from a clinical perspective, including critical functional mechanisms and implications for their potential use as biomarkers and therapeutic targets.

csi-miR-96-5p delivered by Clonorchis sinensis extracellular vesicles promotes intrahepatic cholangiocarcinoma proliferation and migration via the ferroptosis-related PTEN/SLC7A11/GPX4 axis

BACKGROUND

Clonorchis sinensis (CS) is classified as a group 1 carcinogen and can cause intrahepatic cholangiocarcinoma (ICC). CS extracellular vesicles (CsEVs) play important roles in mediating communication between parasitic helminths and humans. Ferroptosis is a novel cell death mechanism that is mainly induced by lipid peroxidation and iron overload. However, the role of CsEVs in the regulation of ferroptosis in ICC remains unclear. This study aimed to explore the role of CS-secreted miR-96-5p (csi-miR-96-5p) delivered by CsEVs in ICC progression and ferroptosis.

METHODS

Tissue samples were collected from ICC patients with CS infection (CS-ICC) or without CS infection (NC-ICC). The levels of csi-miR-96-5p and PTEN gene were determined by quantitative polymerase chain reaction (qPCR) and western blotting, and survival analysis was performed. CsEVs were isolated and identified by ultracentrifugation and transmission electron microscopy. Lentiviruses were used to establish stable cell lines with csi-miR-96-5p mimic expression, PTEN overexpression (PTEN-EXO) and PTEN CRISPR/Cas9-based knockout (PTEN-KO) and their respective negative controls. Cell proliferation was assessed by performing Cell Counting Kit-8 assays in vitro and in a tumor xenograft model in vivo, and cell migration was assessed by performing Transwell assays. Erastin is used to induce ferroptosis. Ferroptosis levels were evaluated using biomarkers.

RESULTS

High csi-miR-96-5p and low PTEN expression was observed in CS-ICC tissues and was associated with poor overall survival. csi-miR-96-5p was highly enriched in CsEVs and was taken up by ICC cells. csi-miR-96-5p mimics or PTEN-KO significantly promoted the growth and migration of ICC cells in vitro and in vivo, whereas PTEN-EXO exerted the opposite effect. Mechanistically, csi-miR-96-5p mimics or PTEN-KO inhibited erastin-induced ferroptosis, including reducing the accumulation of Fe2+, lipid reactive oxygen species, and malondialdehyde, increasing the GSH/GSSG ratio and levels of SLC7A11 and GPX4, whereas PTEN-EXOs exerted the opposite effect.

CONCLUSIONS

csi-miR-96-5p delivered by CsEVs reduced ferroptosis by regulating the expression of the PTEN/SLC7A11/GPX4 axis, thereby promoting ICC proliferation and migration. For the first time to our knowledge, we found that CS miRNAs could promote tumor development through ferroptosis.

Molecular and functional characterization of Schistosoma japonicum annexin A13

Schistosomiasis is a neglected tropical disease that affects humans and animals in tropical and subtropical regions worldwide. Schistosome eggs are responsible for the pathogenesis and transmission of schistosomiasis, thus reducing egg production is vital for prevention and control of schistosomiasis. However, the mechanisms underlying schistosome reproduction remain unclear. Annexin proteins (ANXs) are involved in the physiological and pathological functions of schistosomes, but the specific regulatory mechanisms and roles of ANX A13 in the development of Schistosoma japonicum and host-parasite interactions remain poorly understood. Therefore, in this study, the expression profiles of SjANX A13 at different life cycle stages of S. japonicum were assessed using quantitative PCR. In addition, the expression profiles of the homolog in S. mansoni were analyzed in reference to public datasets. The results of RNA interference showed that knockdown of SjANX A13 significantly affected the development and egg production of female worms in vivo. The results of an immune protection assay showed that recombinant SjANX A13 increased production of immunoglobulin G-specific antibodies. Finally, co-culture of S. japonicum exosomes with LX-2 cells using a transwell system demonstrated that SjANX A13 is involved in host-parasite interactions via exosomes. Collectively, these results will help to clarify the roles of SjANX A13 in the development of S. japonicum and host-parasite interactions as a potential vaccine candidate.

Sja-Let-7 Attenuates Carbon Tetrachloride-Induced Liver Fibrosis in a Mouse Model via Col1α2

Liver fibrosis (LF) is a chronic progressive disease with no definitive treatment. The aim of this study was to assess helminth-derived molecules as potential therapeutic targets to prevent or reverse LF. A mouse model of carbon tetrachloride (CCL4)-induced LF was established and sja-let-7 was overexpressed by treatment with a miRNA agomir once per week. After four weeks, serum biochemistry, hepatic hydroxyproline content measurements, liver histology, mRNA expression profiling of fibrotic markers, the dual-luciferase reporter assay, and fluorescence in situ hybridization (FISH) were performed. Administration of the sja-let-7 agomir markedly ameliorated hepatosplenomegaly and reduced the liver hydroxyproline content. Liver histological analysis showed significant reductions in collagen deposition in the sja-let-7 agomir-treated mice. Additionally, the mRNA levels of both pro-fibrotic markers and pro-inflammatory cytokines were diminished after treatment. Furthermore, the dual-luciferase reporter assay and FISH identified the α2 chain of collagen type 1 (Col1α2) as the direct target of sja-let-7. Accordingly, the progression of LF was attenuated by targeting Col1α2 and the TGF-β/Smad signaling pathway.

Teleost innate immunity, an intricate game between immune cells and parasites of fish organs: who wins, who loses

Fish, comprising over 27,000 species, represent the oldest vertebrate group and possess both innate and adaptive immune systems. The susceptibility of most wild fish to parasitic infections and related diseases is well-established. Among all vertebrates, the digestive tract creates a remarkably favorable and nutrient-rich environment, which, in turn, renders it susceptible to microparasites and macroparasites. Consequently, metazoan parasites emerge as important disease agents, impacting both wild and farmed fish and resulting in substantial economic losses. Given their status as pathogenic organisms, these parasites warrant considerable attention. Helminths, a general term encompassing worms, constitute one of the most important groups of metazoan parasites in fish. This group includes various species of platyhelminthes (digeneans, cestodes), nematodes, and acanthocephalans. In addition, myxozoans, microscopic metazoan endoparasites, are found in water-dwelling invertebrates and vertebrate hosts. It is worth noting that several innate immune cells within the fish alimentary canal and certain visceral organs (e.g., liver, spleen, and gonads) play active roles in the immune response against parasites. These immune cells include macrophages, neutrophils, rodlet cells, and mast cells also known as eosinophilic granular cells. At the site of intestinal infection, helminths often impact mucous cells number and alter mucus composition. This paper presents an overview of the state of the art on the occurrence and characteristics of innate immune cells in the digestive tract and other visceral organs in different fish-parasite systems. The data, coming especially from studies employed immunohistochemical, histopathological, and ultrastructural analyses, provide evidence supporting the involvement of teleost innate immune cells in modulating inflammatory responses to metazoan and protozoan parasitic infections.

Characterisation of extracellular vesicles isolated from hydatid cyst fluid and evaluation of immunomodulatory effects on human monocytes

Hydatidosis is a disease caused by the larval stage of Echinococcus granulosus, which involves several organs of intermediate hosts. Evidence suggests a communication between hydatid cyst (HC) and hosts via extracellular vesicles. However, a little is known about the communication between EVs derived from HC fluid (HCF) and host cells. In the current study, EVs were isolated using differential centrifugation from sheep HCF and characterized by western blot, electron microscope and size distribution analysis. The uptake of EVs by human monocyte cell line (THP-1) was evaluated. The effects of EVs on the expression levels of pro- and anti-inflammatory cytokines were investigated using quantitative real-time PCR (RT-PCR), 3 and 24 h after incubation. Moreover, the cytokine level of IL-10 was evaluated in supernatant of THP-1 cell line at 3 and 24 h. EVs were successfully isolated and showed spherical shape with size distribution at 130.6 nm. After 3 h, the expression levels of pro-inflammatory cytokine genes (IL1Β, IL15 and IL8) were upregulated, while after 24 h, the expression levels of pro-inflammatory cytokines were decreased and IL13 gene expression showed upregulation. A statistically significant increase was seen in the levels of IL-10 after 24 h. The main mechanism of the communication between EVs derived from HCF and their host remains unclear; however, time-dependent anti-inflammatory effects in our study suggest that HC may modulate the immune responses via EVs.

New strategies of neurodegenerative disease treatment with extracellular vesicles (EVs) derived from mesenchymal stem cells (MSCs)

Neurodegenerative diseases are characterized by the progressive loss of neurons and intricate interactions between different cell types within the affected regions. Reliable biomarkers that can accurately reflect disease activity, diagnose, and monitor the progression of neurodegenerative diseases are crucial for the development of effective therapies. However, identifying suitable biomarkers has been challenging due to the heterogeneous nature of these diseases, affecting specific subsets of neurons in different brain regions. One promising approach for promoting brain regeneration and recovery involves the transplantation of mesenchymal stem cells (MSCs). MSCs have demonstrated the ability to modulate the immune system, promote neurite outgrowth, stimulate angiogenesis, and repair damaged tissues, partially through the release of their extracellular vesicles (EVs). MSC-derived EVs retain some of the therapeutic characteristics of their parent MSCs, including their ability to regulate neurite outgrowth, promote angiogenesis, and facilitate tissue repair. This review aims to explore the potential of MSC-derived EVs as an emerging therapeutic strategy for neurodegenerative diseases, highlighting their role in modulating disease progression and promoting neuronal recovery. By elucidating the mechanisms by which MSC-derived EVs exert their therapeutic effects, we can advance our understanding and leverage their potential for the development of novel treatment approaches in the field of neurodegenerative diseases.

How to train your myeloid cells: a way forward for helminth vaccines?

Soil-transmitted helminths affect approximately 1.5 billion people worldwide. However, as no vaccine is currently available for humans, the current strategy for elimination as a public health problem relies on preventive chemotherapy. Despite more than 20 years of intense research effort, the development of human helminth vaccines (HHVs) has not yet come to fruition. Current vaccine development focuses on peptide antigens that trigger strong humoral immunity, with the goal of generating neutralizing antibodies against key parasite molecules. Notably, this approach aims to reduce the pathology of infection, not worm burden, with only partial protection observed in laboratory models. In addition to the typical translational hurdles that vaccines struggle to overcome, HHVs face several challenges (1): helminth infections have been associated with poor vaccine responses in endemic countries, probably due to the strong immunomodulation caused by these parasites, and (2) the target population displays pre-existing type 2 immune responses to helminth products, increasing the likelihood of adverse events such as allergy or anaphylaxis. We argue that such traditional vaccines are unlikely to be successful on their own and that, based on laboratory models, mucosal and cellular-based vaccines could be a way to move forward in the fight against helminth infection. Here, we review the evidence for the role of innate immune cells, specifically the myeloid compartment, in controlling helminth infections. We explore how the parasite may reprogram myeloid cells to avoid killing, notably using excretory/secretory (ES) proteins and extracellular vesicles (EVs). Finally, learning from the field of tuberculosis, we will discuss how anti-helminth innate memory could be harnessed in a mucosal-trained immunity-based vaccine.

Small extracellular vesicles but not microvesicles from Opisthorchis viverrini promote cell proliferation in human cholangiocytes

Chronic infection with O. viverrini has been linked to the development of cholangiocarcinoma (CCA), which is a major public health burden in the Lower Mekong River Basin countries, including Thailand, Lao PDR, Vietnam and Cambodia. Despite its importance, the exact mechanisms by which O. viverrini promotes CCA are largely unknown. In this study, we characterized different extracellular vesicle populations released by O. viverrini (OvEVs) using proteomic and transcriptomic analyses and investigated their potential role in host-parasite interactions. While 120k OvEVs promoted cell proliferation in H69 cells at different concentrations, 15k OvEVs did not produce any effect compared to controls. The proteomic analysis of both populations showed differences in their composition that could contribute to this differential effect. Furthermore, the miRNAs present in 120k EVs were analysed and their potential interactions with human host genes was explored by computational target prediction. Different pathways involved in inflammation, immune response and apoptosis were identified as potentially targeted by the miRNAs present in this population of EVs. This is the first study showing specific roles for different EV populations in the pathogenesis of a parasitic helminth, and more importantly, an important advance towards deciphering the mechanisms used in establishment of opisthorchiasis and liver fluke infection-associated malignancy.

Immunological mechanisms involved in macrophage activation and polarization in schistosomiasis

Human schistosomiasis is caused by helminths of the genus Schistosoma. Macrophages play a crucial role in the immune regulation of this disease. These cells acquire different phenotypes depending on the type of stimulus they receive. M1 macrophages can be ‘classically activated’ and can display a proinflammatory phenotype. M2 or ‘alternatively activated’ macrophages are considered anti-inflammatory cells. Despite the relevance of macrophages in controlling infections, the role of the functional types of these cells in schistosomiasis is unclear. This review highlights different molecules and/or macrophage activation and polarization pathways during Schistosoma mansoni and Schistosoma japonicum infection. This review is based on original and review articles obtained through searches in major databases, including Scopus, Google Scholar, ACS, PubMed, Wiley, Scielo, Web of Science, LILACS and ScienceDirect. Our findings emphasize the importance of S. mansoni and S. japonicum antigens in macrophage polarization, as they exert immunomodulatory effects in different stages of the disease and are therefore important as therapeutic targets for schistosomiasis and in vaccine development. A combination of different antigens can provide greater protection, as it possibly stimulates an adequate immune response for an M1 or M2 profile and leads to host resistance; however, this warrants in vitro and in vivo studies.

Can Echinococcus granulosus-Derived MicroRNAs be Biomarkers for Diagnosis and Follow-up of Cystic Echinococcosis Patients?

INTRODUCTION

Cystic echinococcosis (CE) is a neglected tropical disease caused by the larval stages of Echinococcus granulosus (E. granulosus). MicroRNAs (miRNAs) are small noncoding RNAs acting as mediators in host-parasite interaction. Recently, numerous studies have been conducted on miRNAs in infectious diseases; however, little data are available about the role of miRNAs in pathogenesis and early diagnosis of CE.

METHODS

The current study evaluated the expression of four E. granulosus-derived miRNAs, including egr-miR-125,5p, egr-let-7,5p, egr-miR-2, and egr-miR-71 in fibrotic and healthy liver tissues of 31 CE patients with active and inactive hydatid cysts by qRT-PCR.

RESULTS

Of the 31 patients, 48.4% had active cysts (CE1 and CE2), while the remainder had transitional (16.1%) and inactive (35.5%) CE types cysts. The qRT-PCR analysis revealed a significant increase of 11.2, 9.91, 6.2, and 13.1-fold in the fibrotic tissue group for egr-miR-125,5p, egr-let-7,5p, egr-miR-2, and egr-miR-71, respectively. Among these miRNAs, egr-miR-125-5p exhibited the highest area under the curve (AUC) value of 0.8050 for predicting liver fibrosis.

CONCLUSIONS

Our findings provide new data about the role of E. granulosus-derived miRNAs in pathogenesis of CE. The high AUC of egr-miR125,5p reflecting the possibility of using egr-miR125,5p as biomarker in CE diagnosis. Further studies on serum of CE patients are needed to confirm the potential role of circulating egr-miR-2a-3p and egr-miR-125-5p in the early diagnosis of CE.

Proteomic analysis of exosome-like vesicles from Fasciola gigantica adult worm provides support for new vaccine targets against fascioliasis

BACKGROUND

Extracellular vesicles (EVs) released by helminths play an important role in parasite-host communication. However, little is known about the characteristics and contents of the EVs of Fasciola gigantica, a parasitic flatworm that causes tropical fascioliasis. A better understanding of EVs released by F. gigantica will help elucidate the mechanism of F. gigantica-host interaction and facilitate the search for new vaccine candidates for the control and treatment of fascioliasis.

METHODS

Two different populations of EVs (15k EVs and 100k EVs) were purified from adult F. gigantica culture media by ultracentrifugation. The morphology and size of the purified EVs were determined by transmission electron microscopy (TEM) and by the Zetasizer Nano ZSP high performance particle characterization system. With the aim of identifying diagnostic markers or potential vaccine candidates, proteins within the isolated 100k EVs were analyzed using mass spectrometry-based proteomics (LC-MS/MS). Mice were then vaccinated with excretory/secretory products (ESPs; depleted of EVs), 15k EVs, 100k EVs and recombinant F. gigantica heat shock protein 70 (rFg-HSP70) combined with alum adjuvant followed by challenge infection with F. gigantica metacercariae. Fluke recovery and antibody levels were used as measures of vaccine protection.

RESULTS

TEM analysis and nanoparticle tracking analysis indicated the successful isolation of two subpopulations of EVs (15k EVs and 100k EVs) from adult F. gigantica culture supernatants using differential centrifugation. A total of 755 proteins were identified in the 100k EVs. Exosome biogenesis or vesicle trafficking proteins, ESCRT (endosomal sorting complex required for transport) pathway proteins and exosome markers, heat shock proteins and 14-3-3 proteins were identified in the 100k EVs. These results indicate that the isolated 100k EVs were exosome-like vesicles. The functions of the identified proteins may be associated with immune regulation, immune evasion and virulence. Mice immunized with F. gigantica ESPs, 15k EVs, 100k EVs and rFg-HSP70 exhibited a reduction in fluke burden of 67.90%, 60.38%, 37.73% and 56.6%, respectively, compared with the adjuvant control group. The vaccination of mice with F. gigantica 100k EVs, 15k EVs, ESP and rFg-HSP70 induced significant production of specific immunoglobulins in sera, namely IgG, IgG1 and IgG2a.

CONCLUSION

The results of this study suggest that proteins within the exosome-like vesicles of F. gigantica have immunomodulatory, immune evasion and virulence functions. This knowledge may lead to new strategies for immunotherapy, vaccination and the diagnosis of fascioliasis.

Single-sex schistosomiasis: a mini review

Schistosomiasis is a neglected tropical disease caused by dioecious blood flukes of the genus Schistosoma and second to malaria as a parasitic disease with significant socio-economic impacts. Mating is essential for maturation of male and female schistosomes and for females to lay of eggs, which are responsible for the pathogenesis and propagation of the life cycle beyond the mammalian host. Single-sex schistosomes, which do not produce viable eggs without mating, have been overlooked given the symptomatic paucity of the single-sex schistosomiasis and limited diagnostic toolkit. Besides, single-sex schistosomes are less sensitive to praziquantel. Therefore, these issues should be considered to achieve the elimination of this infection disease. The aim of this review is to summarize current progress in research of single-sex schistosomes and host-parasite interactions.

microRNAs: Critical Players during Helminth Infections

microRNAs (miRNAs) are a group of small non-coding RNAs that regulate gene expression post-transcriptionally through their interaction with the 3' untranslated regions (3' UTR) of target mRNAs, affecting their stability and/or translation. Therefore, miRNAs regulate biological processes such as signal transduction, cell death, autophagy, metabolism, development, cellular proliferation, and differentiation. Dysregulated expression of microRNAs is associated with infectious diseases, where miRNAs modulate important aspects of the parasite-host interaction. Helminths are parasitic worms that cause various neglected tropical diseases affecting millions worldwide. These parasites have sophisticated mechanisms that give them a surprising immunomodulatory capacity favoring parasite persistence and establishment of infection. In this review, we analyze miRNAs in infections caused by helminths, emphasizing their role in immune regulation and its implication in diagnosis, prognosis, and the development of therapeutic strategies.

Circulatory microRNAs in helminthiases: Potent as diagnostics biomarker, its potential role and limitations

Infections caused by helminths are responsible for severe public health problems and economic burden on continental scale. Well-timed and precise diagnosis of helminth infections is critical for taking by appropriate approaches for pathogen control. Circulating miRNAs are stable diagnostic tool for different diseases found in a variety of body fluid. As diagnostic biomarkers in infectious diseases, miRNAs detection in body fluids of helminth infected hosts is growing promptly. Uncovering miRNAs is a relatively new tool, used for early-stage detection of helminth infection from experimental or non-invasive clinical samples. miRNAs can be detected in body fluids such as serum, saliva, urine, and tissues of helminth infected host, mainly blood offering important benefits for diagnosis accurately. In this review, we discuss different characteristics of helminth parasite-derived circulating and EV miRNAs, supporting its potential uses in for helminth diagnosis and treatment efficiency.

Pattern recognition receptor signaling and innate immune responses to schistosome infection

Schistosomiasis remains to be a significant public health problem in tropical and subtropical regions. Despite remarkable progress that has been made in the control of the disease over the past decades, its elimination remains a daunting challenge in many countries. This disease is an inflammatory response-driven, and the positive outcome after infection depends on the regulation of immune responses that efficiently clear worms and allow protective immunity to develop. The innate immune responses play a critical role in host defense against schistosome infection and pathogenesis. Initial pro-inflammatory responses are essential for clearing invading parasites by promoting appropriate cell-mediated and humoral immunity. However, elevated and prolonged inflammatory responses against the eggs trapped in the host tissues contribute to disease progression. A better understanding of the molecular mechanisms of innate immune responses is important for developing effective therapies and vaccines. Here, we update the recent advances in the definitive host innate immune response to schistosome infection, especially highlighting the critical roles of pattern recognition receptors and cytokines. The considerations for further research are also provided.

Modulation of Host-Parasite Interactions with Small Molecules Targeting Schistosoma mansoni microRNAs

Parasites use different strategies of communication with their hosts. One communication channel that has been studied in recent years is the use of vesicle microRNAs to influence the host immune system by trematodes. sma-microRNA-10, secreted from Schistosoma mansoni, has been shown to influence the fate of host T-cells through manipulation of the NF-κB pathway. We have identified low molecular weight tool compounds that can interfere with this microRNA-mediated manipulation of the host immune system. We used a fragment-based screening approach by means of nuclear magnetic resonance (NMR) to identify binders to the precursor of the parasite sma-microRNA-10 present in their extracellular vesicles. The small fragments identified were used to select larger molecules. These molecules were shown to counteract the inhibition of NF-κB activity by sma-microRNA-10 in cell-based assays.

Whipworm secretions and their roles in host-parasite interactions

Whipworm (Trichuris) is a genus of roundworms that causes gastrointestinal infections in humans and animals. Of particular interest are T. trichiura, the causative agent of human trichuriasis, a neglected tropical disease that affects 477 million people worldwide, and T. suis, the pig whipworm species, responsible for growth stunting and economic losses within the agricultural industry. The naturally occurring mouse whipworm, T. muris, has been used for decades as a model for trichuriasis, yielding knowledge on the biology of these parasites and the host response to infection. Ex vivo culture of T. muris (and to some extent, T. suis) has provided insight into the composition of the excretory/secretory (E/S) products released by worms, which include a myriad of proteins, RNAs, lipids, glycans, metabolites and extracellular vesicles. T. muris E/S has formed the basis of the search for whipworm vaccine candidates, while the immunomodulatory potential of T. suis and T. muris secretions has been investigated with the aim of improving our understanding of how these parasites modulate host immunity, as well as identifying immunomodulatory candidates with therapeutic potential in the context of inflammatory diseases. This article will review the various components found within Trichuris E/S, their potential as vaccine candidates and their immunomodulatory properties.

Emerging roles for extracellular vesicles in Schistosoma infection

The co-evolution of Schistosoma and its host necessitates the use of extracellular vesicles (EVs) generated by different lifecycle stages to manipulate the host immune system to achieve a delicate balance between the survival of the parasite and the limited pathology of the host. EVs are phospholipid bilayer membrane-enclosed vesicles capable of transferring a complex mixture of proteins, lipids, and genetic materials to the host. They are nano-scale-sized vesicles involved in cellular communication. In this review, the author summarized the proteins involved in the biogenesis of schistosome-derived EVs and their cargo load. miRNAs are one cargo molecule that can underpin EVs functions and significantly affect parasite/host interactions and immune modulation. They skew macrophage polarization towards the M1 phenotype and downregulate Th2 immunity. Schistosoma can evade the host immune system's harmful effects by utilizing this strategy. In order to compromise the protective effect of Th2, EVs upregulate T regulatory cells and activate eosinophils, which contribute to granuloma formation. Schistosomal EVs also affect fibrosis by acting on non-immune cells such as hepatic stellate cells. These vesicles drew attention to translational applications in diagnosis, immunotherapy, and potential vaccines. A deep understanding of the interaction of schistosome-derived EVs with host cells will significantly increase our knowledge about the dynamics between the host and the worm that may aid in controlling this debilitating disease.

Roles of microRNAs and Long Non-Coding RNAs Encoded by Parasitic Helminths in Human Carcinogenesis

Infectious agents such as viruses, bacteria, and parasites can lead to cancer development. Infection with the helminthic parasite Schistosoma haematobium can cause cancer of the urinary bladder in humans, and infection with the parasites Clonorchis sinensis and Opisthorchis viverrini can promote cholangiocarcinoma. These three pathogens have been categorized as “group 1: carcinogenic to humans” by the International Agency for Research on Cancer (IARC). Additionally, the parasite Schistosoma japonicum has been associated with liver and colorectal cancer and classified as “group 2B: possibly carcinogenic to humans”. These parasites express regulatory non-coding RNAs as microRNAs (miRNAs) and long non-coding RNAs (lncRNAs), which modulate genic expression in different biological processes. In this review, we discuss the potential roles of miRNAS and lncRNAs encoded by helminthic parasites that are classified by the IARC as carcinogenic and possibly carcinogenic to humans. The miRNAs of these parasites may be involved in carcinogenesis by modulating the biological functions of the pathogen and the host and by altering microenvironments prone to tumor growth. miRNAs were identified in different host fluids. Additionally, some miRNAs showed direct antitumoral effects. Together, these miRNAs show potential for use in future therapeutic and diagnostic applications. LncRNAs have been less studied in these parasites, and their biological effects in the parasite–host interaction are largely unknown.