ABSTRACT: Exosomes secreted by a nematode parasite transfer small RNAs to mammalian cells and regulate genes of the innate immune system [Litomosoides sigmodontis]
Project description:The filarial nematodes Brugia malayi, Wuchereria bancrofti and Onchocerca volvulus cause elephantiasis, dermatitis and blindness, resulting in severe morbidity in developing countries. 1.3 billion people are at risk of infection. Targeting the essential Wolbachia endobacteria of filarial nematodes with doxycycline has proven to be an effective therapy, resulting in a block in embryogenesis and worm development, and macrofilaricidal effects. However, doxycycline is contraindicated for a large portion of the at-risk population. To identify new targets for anti-wolbachial therapy, understanding the molecular basis of the Wolbachia-filaria symbiosis is required. We performed cross-species hybridization by using the Brugia malayi microarray to identify differentially expressed genes in the rodent filaria Litomosoides sigmodontis after depletion of Wolbachia which therefore might have a role in symbiosis. Female adult Litomosoides sigmodontis from patent infections were treated with tetracycline to deplete endosymbiotic Wolbachia bacteria. RNA from tetracycline-treated Litomosoides sigmodontis was compared to untreated age-matched control worms. This experiment was performed for three different timepoints: day 6, 15 and 36 of tetracycline treatment. One biological replicate was performed each with two technical replicates (dye-flip replicates).
Project description:In mammalian systems, extracellular small RNAs can operate in a paracrine manner to communicate information between cells, relying on transport within vesicles. “Foreign” small RNAs derived from bacteria, plants and parasites have also been detected in mammalian body fluids, sparking interest in whether these could mediate inter-species communication. However, there is no mechanistic framework for RNA-mediated interspecies communication and the active movement of RNA via vesicles has not been shown outside of mammals. Here we demonstrate that specific microRNAs and Y RNAs are packaged into vesicles secreted by a gastrointestinal nematode, Heligmosomoides polygyrus, which naturally infects mice. Total RNA was extracted from the serum of mice infected with Litomosoides sigmodontis at 60 days post infection
Project description:The filarial nematodes Brugia malayi, Wuchereria bancrofti and Onchocerca volvulus cause elephantiasis, dermatitis and blindness, resulting in severe morbidity in developing countries. 1.3 billion people are at risk of infection. Targeting the essential Wolbachia endobacteria of filarial nematodes with doxycycline has proven to be an effective therapy, resulting in a block in embryogenesis and worm development, and macrofilaricidal effects. However, doxycycline is contraindicated for a large portion of the at-risk population. To identify new targets for anti-wolbachial therapy, understanding the molecular basis of the Wolbachia-filaria symbiosis is required. We performed cross-species hybridization by using the Brugia malayi microarray to identify differentially expressed genes in the rodent filaria Litomosoides sigmodontis after depletion of Wolbachia which therefore might have a role in symbiosis.
Project description:BACKGROUND: The release of small non-coding RNAs (sRNAs) has been reported in parasitic nematodes, trematodes and cestodes of medical and veterinary importance. However, little is known regarding the diversity and composition of sRNAs released by different lifecycle stages and the portion of sRNAs that persist in host tissues during filarial infection. This information is relevant to understanding potential roles of sRNAs in parasite-to-host communication, as well as to inform on the location within the host and time point at which they can be detected. METHODOLOGY & PRINCIPAL FINDINGS: We have used small RNA (sRNA) sequencing analysis to identify sRNAs in replicate samples of the excretory-secretory (ES) products of developmental stages of the filarial nematode Litomosoides sigmodontis in vitro and compare this to the parasite-derived sRNA detected in host tissues. We show that all L. sigmodontis developmental stages release RNAs in vitro, including ribosomal RNA fragments, 5’-derived tRNA fragments (5’-tRFs) and, to a lesser extent, microRNAs (miRNAs). The gravid adult females (gAF) produce the largest diversity and abundance of miRNAs in the ES compared to the adult males or microfilariae. Analysis of sRNAs detected in serum and macrophages from infected animals reveals that the class of parasite miRNAs are preferentially detected in vivo, compared to their low levels in the ES products, and identifies miR-92-3p and miR-71-5p as L. sigmodontis miRNAs that are stably detected in host cells in vivo. CONCLUSIONS: Our results suggest that gravid adult female worms secrete the largest diversity of extracellular sRNAs compared to adult males or microfilariae. We further show differences in the parasite sRNA biotype distribution detected in vitro versus in vivo. We identify macrophages as one reservoir for parasite sRNA during infection, and confirm the presence of parasite miRNAs and tRNAs in host serum during patent infection.
Project description:Litomosoides sigmodontis is parasitic filarial nematode that can infect mice, and is used as a murine model for human filariasis. Type 2 immune responses are protective, but infection is typically chronic due to a combination of immune suppression by the parasite and immune regulation by the host dampening protective Type 2 immunity. We have shown that the CD4+ Th2 cells develop an intrinsically hyporesponsive or dysfunctional phenotype between day 20 and 60 of infection, denoted by an impaired ability to proliferate and produce Th2 cytokines. The hyporesponsive phenotype is PD-1/PD-L2 dependent, and impairs parasite killing (van der Werf et al. 2013. PloS Path. e1003215). This study aimed to investigate the mRNA expression of the intrinsically-hyporesponsive Th2 cells to determine the mechanisms by which they become dysfunctional, and to test whether Th2 cell intrinsic hyporesponsiveness has similarities with other forms of T cell-intrinsic regulation such as exhaustion, tolerance or anergy.
Project description:Filarial nematodes (superfamily Filarioidea) are responsible for an annual global health burden of approximately 6.3 million disability-adjusted life-years, which represents the greatest single component of morbidity attributable to helminths affecting humans. No vaccine exists for the major filarial diseases, lymphatic filariasis and onchocerciasis; in part because research on protective immunity against filariae has been constrained because the human-parasitic species cannot complete their lifecycles in laboratory mice. However, the rodent filaria Litomosoides sigmodontis has become a popular experimental model, as BALB/c mice are fully permissive for its development and reproduction. Here, we provide a comprehensive analysis of excretory-secretory products from L. sigmodontis across five lifecycle stages. Applying intensity-based quantification, we determined the abundance of 302 unique excretory-secretory proteins, of which 64.6% were present in quantifiable amounts only from gravid adult female nematodes. This lifecycle stage, together with immature first-stage larvae (microfilariae), released four proteins that have not previously been evaluated as vaccine candidates: a predicted 28.5 kDa filaria-specific protein, a zonadhesin and SCO-spondin-like protein, a vitellogenin, and a protein containing six metridin-like ShK toxin domains. Female nematodes also released two proteins derived from the obligate Wolbachia symbiont. Notably, excretory-secretory products from all parasite stages contained several uncharacterised members of the transthyretin-like protein family. Furthermore, biotin labelling revealed that redox proteins and enzymes involved in purinergic signalling were enriched on the adult nematode cuticle. Comparison of the L. sigmodontis adult secretome with that of the human–infective filarial nematode Brugia malayi (reported previously in three independent published studies) identified differences that suggest a considerable underlying diversity of potential immunomodulators. The molecules identified in L. sigmodontis excretory-secretory products show promise not only for vaccination against filarial infections, but for the amelioration of allergy and autoimmune diseases.