Trichinella spiralis muscle larvae release extracellular vesicles with immunomodulatory properties

Trichinella spiralis Larval Extract as a Biological Anti-Tumor Therapy in a Murine Model of Ehrlich Solid Carcinoma

Trichinella spiralis (T. spiralis) is an immunomodulating parasite that can adversely affect tumor growth and extend host lifespan. The aim of this study was to elucidate the mechanisms by which T. spiralis larval antigens achieve this effect using Ehrlich solid carcinoma (ESC) murine model. Assessment was done by histopathological and immunohistochemical analysis of caspase-3, TNF-α, Ki-67 and CD31. Additionally, Bcl2 and Bcl2-associated protein X (Bax) relative gene expression was assessed by molecular analysis for studying the effect of T. spiralis crude larval extract (CLE) antigen on tumor necrosis, apoptosis, cell proliferation and angiogenesis. We found that both T. spiralis infection and CLE caused a decrease in the areas of necrosis in ESC. Moreover, they led to increased apoptosis through activation of caspase-3, up-regulation of pro-apoptotic gene, Bax and down-regulation of anti-apoptotic gene, Bcl2. Also, T. spiralis infection and CLE diminished ESC proliferation, as evidenced by decreasing Ki-67. T. spiralis infection and CLE were able to suppress the development of ESC by inhibiting tumor proliferation, inducing apoptosis and decreasing tumor necrosis, with subsequent decrease in tumor metastasis. T. spiralis CLE antigen may be considered as a promising complementary immunotherapeutic agent in the treatment of cancer.

Trichinella spiralis dipeptidyl peptidase 1 suppressed macrophage cytotoxicity by promoting M2 polarization via the STAT6/PPARγ pathway

Trichinella spiralis dipeptidyl peptidase 1 (TsDPP1), or cysteine cathepsin C, is a secretory protein that is highly expressed during the infective larvae and adult worm stages in the intestines. The aim of this study was to investigate the mechanism by which recombinant TsDPP1 (rTsDPP1) activates macrophages M2 polarization and decreases macrophage cytotoxicity to kill newborn larvae via ADCC. RAW264.7 macrophages and murine peritoneal macrophages were used in this study. The results of the immunofluorescence test (IFT) and confocal microscopy showed that rTsDPP1 specifically bound to macrophages, and the binding site was localized on the cell membrane. rTsDPP1 activated macrophage M2 polarization, as demonstrated by high expression levels of Arg1 (M2 marker) and M2-related genes (IL-10, TGF-β, CD206 and Arg1) and high numbers of CD206+ macrophages. Furthermore, the expression levels of p-STAT6, STAT6 and PPARγ were obviously increased in rTsDPP1-treated macrophages, which were evidently abrogated by using a STAT6 inhibitor (AS1517499) and PPARγ antagonist (GW9662). The results indicated that rTsDPP1 promoted macrophage M2 polarization through the STAT6/PPARγ pathway. Griess reaction results revealed that rTsDPP1 suppressed LPS-induced NO production in macrophages. qPCR and flow cytometry results showed that rTsDPP1 downregulated the expression of FcγR I (CD64) in macrophages. The ability of ADCC to kill newborn larvae was significantly decreased in rTsDPP1-treated macrophages, but AS1517499 and GW9662 restored its killing capacity. Our results demonstrated that rTsDPP1 induced macrophage M2 polarization, upregulated the expression of anti-inflammatory cytokines, and inhibited macrophage-mediated ADCC via activation of the STAT6/PPARγ pathway, which is beneficial to the parasitism and immune evasion of this nematode.

Immunomodulatory in vitro effects of Trichinella cystatin-like protein on mouse splenocytes

Trichinella parasites have developed specific mechanisms allowing successful completion of their life cycle. These mechanisms are in a great part involved in immunomodulation and studying them may provide a valuable insight into the functioning of the immune system. Trichinella products may be also used as potential therapeutic agents to treat immune diseases. This study investigates the immunomodulatory potential of recombinant multi cystatin-like protein (CLP) derived from T. britovi to determine whether CLP has anti-inflammatory properties in vitro. CLP is a highly antigenic glycoprotein present in Trichinella excetory-secretory (ES) products. AlphaFold structure prediction confirms that it consists of three type-two cystatin-like domains. Mouse splenocytes were stimulated in vitro with lipopolysaccharide (LPS) and co-stimulated with recombinant CLP. The culture supernatants were collected and tested for secreted cytokine levels using ELISA. CLP was found to reduce LPS-induced secretion of inflammatory cytokines TNFα and IL-6. On the contrary, in some experimental groups, co-stimulation with CLP resulted in increased secretion of the regulatory cytokine IL-10. The obtained results indicate that CLP has anti-inflammatory properties and future research on its function is advisable, specifically in the context of the therapy of inflammatory disorders.

Extracellular vesicles secreted by Brugia malayi microfilariae modulate the melanization pathway in the mosquito host

Vector-borne, filarial nematode diseases cause significant disease burdens in humans and domestic animals worldwide. Although there is strong direct evidence of parasite-driven immunomodulation of mammalian host responses, there is less evidence of parasite immunomodulation of the vector host. We have previously reported that all life stages of Brugia malayi, a filarial nematode and causative agent of Lymphatic filariasis, secrete extracellular vesicles (EVs). Here we investigate the immunomodulatory effects of microfilariae-derived EVs on the vector host Aedes aegypti. RNA-seq analysis of an Ae. aegypti cell line treated with B. malayi microfilariae EVs showed differential expression of both mRNAs and miRNAs. AAEL002590, an Ae. aegypti gene encoding a serine protease, was shown to be downregulated when cells were treated with biologically relevant EV concentrations in vitro. Injection of adult female mosquitoes with biologically relevant concentrations of EVs validated these results in vivo, recapitulating the downregulation of AAEL002590 transcript. This gene was predicted to be involved in the mosquito phenoloxidase (PO) cascade leading to the canonical melanization response and correspondingly, both suppression of this gene using RNAi and parasite EV treatment reduced PO activity in vivo. Our data indicate that parasite-derived EVs interfere with critical immune responses in the vector host, including melanization.

Extracellular vesicles derived from Trichinella Spiralis larvae promote the polarization of macrophages to M2b type and inhibit the activation of fibroblasts

Trichinella spiralis (T. spiralis) is a globally distributed food-borne parasite that can coexist with the host for a long time after infection. Trichinella-derived secretions can regulate the immune response and fibroblasts of the host, but the specific mechanisms involved are still unclear. The purpose of this study was to investigate the role of T. spiralis larvae-derived extracellular vesicles (EVs) and their key miRNAs in the process of T. spiralis–host interaction. In this study, we found that the EVs of T. spiralis larvae, as well as miR-1-3p and let-7-5p, expressed in T. spiralis larvae-derived EVs, can promote the polarization of bone marrow macrophages to M2b type while inhibiting the activation of fibroblasts. These findings will contribute to further understanding of the molecular mechanisms underlying T. spiralis–host interactions.

Secreted filarial nematode galectins modulate host immune cells

Lymphatic filariasis (LF) is a mosquito-borne disease caused by filarial nematodes including Brugia malayi. Over 860 million people worldwide are infected or at risk of infection in 72 endemic countries. The absence of a protective vaccine means that current control strategies rely on mass drug administration programs that utilize inadequate drugs that cannot effectively kill adult parasites, thus established infections are incurable. Progress to address deficiencies in the approach to LF control is hindered by a poor mechanistic understanding of host-parasite interactions, including mechanisms of host immunomodulation by the parasite, a critical adaptation for establishing and maintaining infections. The canonical type 2 host response to helminth infection characterized by anti-inflammatory and regulatory immune phenotypes is modified by filarial nematodes during chronic LF. Current efforts at identifying parasite-derived factors driving this modification focus on parasite excretory-secretory products (ESP), including extracellular vesicles (EVs). We have previously profiled the cargo of B. malayi EVs and identified B. malayi galectin-1 and galectin-2 as among the most abundant EV proteins. In this study we further investigated the function of these proteins. Sequence analysis of the parasite galectins revealed highest homology to mammalian galectin-9 and functional characterization identified similar substrate affinities consistent with this designation. Immunological assays showed that Bma-LEC-2 is a bioactive protein that can polarize macrophages to an alternatively activated phenotype and selectively induce apoptosis in Th1 cells. Our data shows that an abundantly secreted parasite galectin is immunomodulatory and induces phenotypes consistent with the modified type 2 response characteristic of chronic LF infection.

Trichinella-induced immunomodulation: Another tale of helminth success

Trichinella spiralis is a unique parasite in that both the adults and larvae survive in two different intracellular niches in the same host. The immune response, albeit intense, is highly modulated to ensure the survival of both the host and the parasite. It is skewed to T helper 2 and regulatory arms. Diverse cells from both the innate and adaptive compartments of immunity, including dendritic cells, T regulatory cells, and alternatively activated macrophages are thought to mediate such immunomodulation. The parasite has also an outstanding ability to evade the immune system by several elaborate processes. The molecules derived from the parasites including Trichinella, particularly the components of the excretory-secretory products, are being continually identified and explored for the potential of ameliorating the immunopathology in animal models of diverse inflammatory and autoimmune human diseases. Herein we discuss the various aspects of Trichinella-induced immunomodulation with a special reference to the practical implications of the immune system manipulation in alleviating or possibly curing human diseases.

Peptide of Trichinella spiralis Infective Larval Extract That Harnesses Growth of Human Hepatoma Cells

Trichinella spiralis, a tissue-dwelling helminth, causes human trichinellosis through ingestion of undercooked meat containing the parasite’s infective larvae. However, benefits from T. spiralis infection have been documented: reduction of allergic diseases, inhibition of collagen-induced arthritis, delay of type 1 diabetes progression, and suppression of cancer cell proliferation. Since conventional cancer treatments have limited and unreliable efficacies with adverse side effects, novel adjunctive therapeutic agents and strategies are needed to enhance the overall treatment outcomes. This study aimed to validate the antitumor activity of T. spiralis infective larval extract (LE) and extricate the parasite-derived antitumor peptide. Extracts of T. spiralis infective larvae harvested from striated muscles of infected mice were prepared and tested for antitumor activity against three types of carcinoma cells: hepatocellular carcinoma HepG2, ovarian cancer SK-OV-3, and lung adenocarcinoma A549. The results showed that LE exerted the greatest antitumor effect on HepG2 cells. Proteomic analysis of the LE revealed 270 proteins. They were classified as cellular components, proteins involved in metabolic processes, and proteins with diverse biological functions. STRING analysis showed that most LE proteins were interconnected and played pivotal roles in various metabolic processes. In silico analysis of anticancer peptides identified three candidates. Antitumor peptide 2 matched the hypothetical protein T01_4238 of T. spiralis and showed a dose-dependent anti-HepG2 effect, not by causing apoptosis or necrosis but by inducing ROS accumulation, leading to inhibition of cell proliferation. The data indicate the potential application of LE-derived antitumor peptide as a complementary agent for human hepatoma treatment.

Liquid Biopsy for Promising Non-invasive Diagnostic Biomarkers in Parasitic Infections

BACKGROUND

Liquid biopsy refers to the sampling and molecular analysis of body fluids such as blood, saliva, and urine in contrast to conventional tissue biopsies. Liquid biopsy approach can offer powerful non-invasive biomarkers (circulating markers) for diagnosis and monitoring treatment response of a variety of diseases, including parasitic infections.

METHODS

In this review, we concentrate on cell-free DNA (cfDNA), microRNA (miRNA), and exosomes in the published literature.

RESULTS

Considering the high prevalence and severity of parasitic infections worldwide, circulating biomarkers can provide a new insight into the diagnosis and prognosis of parasites in the near future. Moreover, identifying and characterizing parasite- or host-derived circulating markers are important for a better understanding of the pathogenesis of parasite infection and host-parasite relationship at the molecular level. Profiling of biomarkers for parasitic diseases is a promising potential field, though further studies and optimization strategies are required, both in vitro and in vivo.

CONCLUSION

In this review, we discuss three approaches in the liquid biopsy including circulating cfDNA, miRNAs, and exosomes for diagnosis and evaluation of parasites and summarize circulating biomarkers in non-invasive samples during parasitic infections.

Helminth extracellular vesicles: Interactions with the host immune system

As long-lived parasites, helminths depend upon immunomodulation of their hosts for survival. The release of excretory-secretory (ES) products, including proteins, lipids and RNAs is how successful host manipulation is achieved. It has recently been discovered that the ES products of helminths contain extracellular vesicles (EVs), with every species investigated found to secrete these lipid-bound structures. EVs are perfect for packaging and delivering immune modulators to target cell types. This review outlines the research carried out on helminth EVs and their constituents thus far, as well as their interaction with components of the mammalian immune system. We discuss how targeting EVs will aid treatment of helminth infection and consider how EVs and their immunomodulatory cargo could be used as therapeutics as we progress through this exciting era.

Harnessing immunomodulatory mechanisms of Trichinella spiralis to design novel nanomedical approaches for restoring self-tolerance in autoimmunity

The rapid increase in the prevalence of autoimmune diseases in recent decades, especially in developed countries, coincided with improved living conditions and healthcare. Part of this increase could be ascribed to the lack of exposure to infectious agents like helminths that co-evolved with us and display potent immune regulatory actions. In this review we discussed many investigations, including our own, showing that Trichinella spiralis via its excretory-secretory products attenuate Th1/Th17 immunopathological response in autoimmunity and potentiate the protective Th2 and or regulatory T cell response, acting as an effective induction of tolerogenic dendritic cells (DCs), and probably mimicking the autoantigen in some diseases. A recent discovery of T. spiralis extracellular vesicles (TsEVs) suggested that inducing a complex regulation of the immune response requires simultaneous delivery of different signals in nano-sized packages. Indeed, different artificial nanomedical approaches discussed here suggested that co-delivery of multiple signals via nanoparticles is the most promising strategy for the treatment of autoimmune diseases. Although a long way is ahead of us before we could completely replicate natural nano-delivery systems which are both safe and potent in restoring self-tolerance, a clear path is being opened from a careful examination of parasite-host interactions.

Overview of the interaction of helminth extracellular vesicles with the host and their potential functions and biological applications

Helminth Extracellular Vesicles (EVs) have emerged as important mediators in host-parasite communications, participating in the parasite survival and its pathogenic effects. In the last decade, a growing amount of information reporting the isolation and characterization of EVs from different helminth species has appeared, but unfortunately, few reports have focused on functional studies of helminth EVs in different cell lines, organoids or animal models. We here review these in vitro and in vivo studies, which clearly demonstrate that helminths secrete EVs, which affect their environment. Helminth EVs are actively internalized by different cell lines, modulating cellular functions important for host-parasite communication. We discuss how these lines of investigation should provide potential new biomarkers of infection, and since helminth EVs can modulate the host immune response, we also discuss how they can provide a new landscape for the development of new vaccine tools against helminthiases as well as immunotherapy.

Mining Helminths for Novel Therapeutics

Helminths are an emerging source of therapeutics for dysregulated inflammatory diseases. Excretory/secretory (ES) molecules, released during infection, are responsible for many of these immunomodulatory effects and are likely to have evolved as a means for parasite survival in the host. While the mechanisms of action of these molecules have not been fully defined, evidence demonstrates that they target various pathways in the immune response, ranging from initiation to effector cell modulation. These molecules are applied in controlling specific effector mechanisms of type 1 and type 2 immune responses. Recently, studies have further focused on their therapeutic potential in specific disease models. Here we review recent findings on ES molecule modulation of immune functions, specifically highlighting their clinical implications for future use in inflammatory disease therapeutics.

Therapeutic Efficacy of Excretory-Secretory Products of Trichinella spiralis Adult Worms on Sepsis-Induced Acute Lung Injury in a Mouse Model

Acute lung injury (ALI) is a common complication of systemic inflammation or sepsis with high morbidity and mortality. Although many studies have confirmed that helminth-derived proteins had strong immunomodulatory functions and could be used to treat inflammatory diseases, there is no report on the therapeutic effect of excretory-secretory products of Trichinella spiralis adult worms (Ts-AES) on sepsis-induced ALI. In this study, the therapeutic efficacy of Ts-AES on sepsis-induced ALI and the underlying immunological mechanism and the signaling pathway were investigated. The results indicated that after being treated with Ts-AES, the survival rate of mice with CLP-induced sepsis was significantly increased to 50% for 72 hours after CLP surgery compared to PBS control group with all mice died. The sepsis-induced ALI was largely mitigated characterized by reduced inflammation cell infiltration and pathological changes in lung tissue, with decreased lung injury scores and lung wet/dry weight ratio. The therapeutic efficacy of Ts-AES is associated with stimulated Tregs response with increased regulatory cytokines IL-10 and TGF-β and downregulated pro-inflammatory cytokines (TNF-α, IL-6, IL-1β). The expression of HMGB1, TLR2 and MyD88 in lung tissue was inhibited after treatment of Ts-AES. Our results demonstrated that Ts-AES play an important role in immunomodulation and confer a therapeutic effect on sepsis-induced ALI through inhibiting pro-inflammatory cytokines. The activation of Tregs and increased level of regulatory cytokines IL-10 and TGF-β are possibly involved in the immunomodulatory functions of Ts-AES through HMGB1/TLR2/MyD88 signal pathway. The findings suggest Ts-AES is a potential therapeutic agent for prevention and treatment of sepsis-induced ALI and other inflammatory diseases.

Extracellular vesicles derived from Trichinella spiralis prevent colitis by inhibiting M1 macrophage polarization

Extracellular vesicles (EVs) are membranous containers released by cells that are powerful agents of intercellular communication. EVs have been described for various parasites and are associated with tissue inflammation. Several studies have demonstrated that parasite EVs can have either pro- or anti-inflammatory impacts, depending on the type of parasite. To evaluate the immunomodulatory properties of EVs produced by Trichinella spiralis (T. spiralis), we established a mouse model with dextran sulphate sodium (DSS)-induced colitis. The muscle larvae of T. spiralis were cultured in vitro and the released EVs were isolated by ultracentrifugation. T. spiralis EVs (Ts-EVs) were characterized according to morphology, size and constituent surface proteins (CD63, Enolase and Hsp70). Mice were treated with water containing 3% DSS after last intraperitoneal injection of Ts-EVs. Disease activity index (DAI), macroscopic and histopathological scores of Ts-EVs group was lower than DSS group. And Ts-EVs prevented the increase in the expression of TNF-α, IFN-γ, IL-17A and IL-1β observed in the colon of DSS-treated mice. In contrast, upregulation of IL-4, IL-10, TGF-β and IL-13 expression was detected in Ts-EVs+DSS group. In addition, Ts-EVs increased the infiltration of alternatively activated (M2) macrophages into the colon. The expression of CD206 (M2 marker) in the mesenteric lymph nodes (MLN) of mice with colitis increased in Ts-EVs+DSS group. Furthermore, Ts-EVs interfered with both the NF-κB and MAPK signalling pathways. Taken together, our findings demonstrate that Ts-EVs can affect the development of inflammation in DSS-induced colitis by inhibiting M1 macrophage polarization, due to their immunomodulatory ability.

Trichinella spiralis: inflammation modulator

The hygiene hypothesis posits that the decreased incidence of parasitic infection in developed countries may underlie an increased prevalence of allergic and autoimmune diseases in these countries. As unique inflammation modulator of intracellular parasitism, Trichinella spiralis, or its excretory-secretory (ES) product, shows improved responses to allergies, autoimmune diseases, inflammatory bowel disease, type 1 diabetes, rheumatic arthritis and autoimmune encephalomyelitis by exerting immunomodulatory effects on both innate and adaptive immune cells in animal models. Research has shown that T. spiralis differs from other helminths in manipulation of the host immune response not only by well-known characteristics of its life cycle, but also by its inflammation modulation pathway. How the parasite achieves inflammation modulation has not been fully elucidated yet. This review will generalize the mechanism and focuses on ES immunomodulatory molecules of T. spiralis that may be important for developing new therapeutics for inflammatory disorders.

Extracellular vesicles: new targets for vaccines against helminth parasites

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Current vaccine candidates against helminth infection have shown limited success.

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Helminths release extracellular vesicles (EVs) which act on host cells and are a rich source of antigens for new vaccines.

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The biogenesis, release and immunomodulatory functions of helminth EVs are reviewed.

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Utilisation of EVs in vaccine generation are discussed, including potential antigens and routes of delivery.

The hunt for effective vaccines against the major helminth diseases of humans has yet to bear fruit despite much effort over several decades. No individual parasite antigen has proved to elicit full protective immunity, suggesting that combinatorial strategies may be required. Recently it has been discovered that extracellular vesicles released by parasitic helminths contain multiple potential immune modulators, which could together be targeted by a future vaccine. Increasing knowledge of helminth extracellular vesicle components, both enclosed by and exposed on the membrane, will open up a new field of targets for an effective vaccine. This review discusses the interactions between helminth extracellular vesicles and the immune system discovered thus far, and the advantages of targeting these lipid-bound packages with a vaccine. In addition, we also comment upon specific antigens that may be the best targets for an anti-helminth vaccine. In the future, extensive knowledge of the parasites' full arsenal in controlling their host may finally provide us with the ideal target for a fully effective vaccine.

The protein and microRNA cargo of extracellular vesicles from parasitic helminths - current status and research priorities

Helminth parasites have a remarkable ability to persist within their mammalian hosts, which is largely due to their secretion of molecules with immunomodulatory properties. Although the soluble components of helminth secretions have been extensively studied, the discovery that helminths release extracellular vesicles (EVs) has added further complexity to the host-parasite interaction. Whilst several studies have begun to characterise the molecules carried by helminth EVs, work aimed at investigating their biological functions has been hindered by a lack of helminth-specific EV markers. To begin to address this, we summarised helminth EV literature to date. With a focus on the protein and microRNA (miRNA) cargo, we aimed to detect similarities and differences across those major groups of helminths for which data are available; namely nematodes, trematodes and cestodes. Pfam analysis revealed that although there is no universal EV marker for all helminth species, the EF-hand protein family was present in all EV datasets from cestodes and trematodes, and could serve as a platyhelminth EV biomarker. In contrast, M13 metallopeptidases and actin may have potential as markers for nematode EVs. As with proteins, many miRNA families appeared to be species-, stage-, or dataset-specific. Two miRNA families were common to nematode EVs (mir-10 and let-7); the miRNA cargo of EVs secreted by clade I species appeared somewhat different from species from other clades. Five miRNA families (mir-71, mir-10, mir-190, let-7 and mir-2) were shared by all trematode species examined. Our analysis has identified novel markers that may be used in studies aimed at characterising helminth EVs and interrogating their function at the host-parasite interface. In addition, we discuss the heterogeneity of methods used for helminth EV isolation and emphasise the need for a standardised approach in reporting on helminth EV data.

Extracellular Vesicles Derived From Trichinella spiralis Muscle Larvae Ameliorate TNBS-Induced Colitis in Mice

Helminths are masters at modulating the host immune response through a wide variety of versatile mechanisms. These complex strategies facilitate parasite survival in the host and can also be exploited to prevent chronic immune disorders by minimizing excessive inflammation. Extracellular vesicles (EVs) are small membrane-bound structures secreted by helminths which mediate immune evasion during parasite infection. The goal of this study was to investigate the immunoregulatory properties of Trichinella spiralis EVs (Ts-EVs) in a murine model of colitis. We found that Ts-EVs significantly ameliorated 2,4,6-trinitrobenzene sulfonic acid (TNBS)-induced colitis in mice. Ts-EVs alleviated intestinal epithelium barrier damage, markedly reduced pro-inflammatory cytokine secretion and neutrophil infiltration, and upregulated immunoregulatory cytokine expression in colon tissue. Ts-EVs also modulated the adaptive immune response by influencing T-cell composition. The numbers of Th1 and Th17 cells in MLNs, as well as the expression levels of Th1/Th17-associated cytokines and transcription factors in colon were reduced. In contrast, Th2 and Treg cells were increased after Ts-EVs treatment. Furthermore, sequencing of EV-derived microRNAs (miRNAs) indicated that an array of miRNAs was involved in the regulation of the host immune response, including inflammation. These findings expand our knowledge of host-parasite interactions, and may help design novel and effective strategies to prevent parasite infections or to treat inflammatory diseases like IBD. Further studies are needed to identify the specific cargo molecules carried by Ts-EVs and to clarify their roles during T. spiralis infection.

Diversity of extracellular vesicles from different developmental stages of Fasciola hepatica

The secretion of extracellular vesicles (EVs) in Fasciola hepatica adult worms was described by our group in 2012. Since then, EVs have been found in other helminths, thus providing a new paradigm for the complete understanding of host-parasite communication. However, information was lacking regarding the possible existence and role of EVs from other developmental stages of the parasite. In this study, we confirm the secretion of EVs by F. hepatica eggs and juvenile forms. EVs were isolated by size exclusion chromatography and characterised by nanoparticle tracking analysis and electron microscopy. We observed a large diversity in the morphologies of these EVs, suggesting specific functions for different subpopulations, as has been proposed in other model systems. The identification of these populations of morphologically diverse EVs will facilitate future studies aimed at biochemically characterising the different classes of these vesicles as a first step in deciphering their role in host-parasite communication.

Preliminary Trichinella spiralis Infection Ameliorates Subsequent RSV Infection-Induced Inflammatory Response

Respiratory syncytial virus (RSV) infection affects the lives of neonates throughout the globe, causing a high rate of mortality upon hospital admission. Yet, therapeutic options to deal with this pulmonary pathogen are currently limited. Helminth therapy has been well received for its immunomodulatory role in hosts, which are crucial for mitigating a multitude of diseases. Therefore, in this study, we used the helminth Trichinella spiralis and assessed its capabilities for modulating RSV infection as well as the inflammatory response induced by it in mice. Our results revealed that RSV-specific antibody responses were enhanced by pre-existing T. spiralis infection, which also limited pulmonary viral replication. Diminished lung inflammation, indicated by reduced pro-inflammatory cytokines and inflammatory cell influx was confirmed, as well as through histopathological assessment. We observed that inflammation-associated nuclear factor kappa-light-chain enhancement of activated B cells (NF-κB) and its phosphorylated forms were down-regulated, whereas antioxidant-associated nuclear factor erythroid 2-related factor 2 (Nrf2) protein expression was upregulated in mice co-infected with T. spiralis and RSV. Upregulated Nrf2 expression contributed to increased antioxidant enzyme expression, particularly NQO1 which relieved the host of oxidative stress-induced pulmonary inflammation caused by RSV infection. These findings indicate that T. spiralis can mitigate RSV-induced inflammation by upregulating the expression of antioxidant enzymes.