Trematodes of the order Diplostomida are well known as serious pathogens of man, and both farm and wild animals; members of the genus Schistosoma (Schistosomatidae) are responsible for human schistosomosis (schistosomiasis) affecting more than 200 million people in tropical and subtropical countries, and infections of mammals and birds by animal schistosomes are of great veterinary importance. The order Diplostomida is also rich in species parasitizing other major taxa of vertebrates. The "Aporocotylidae" sensu lato are pathogenic in fish, "Spirorchiidae" sensu lato in reptiles. All these flukes have two-host life cycles, with asexually reproducing larvae usually in mollusks and occasionally in annelids, and adults usually live in the blood vessels of their vertebrate hosts. Pathology is frequently associated with inflammatory reactions to eggs trapped in various tissues/organs. On the other hand, the representatives of Diplostomidae and Strigeidae have three- or four-host life cycles in which vertebrates often serve not only as definitive but also as intermediate or paratenic hosts. Pathology is usually associated with migration of metacercariae and mesocercariae within the host tissues. The impact of these trematode infections on both farm and wild animals may be significant.

• Klíčová slova
• Aporocotylidae, Blood flukes, Diplostomidae, Sanguinicolidae, Schistosoma, Schistosomatidae, Skin penetration, Spirorchiidae, Strigeidae, Trematodes,
• MeSH
• infekce červy třídy Trematoda * parazitologie   veterinární   MeSH
• interakce hostitele a parazita MeSH
• lidé MeSH
• Schistosomatidae genetika   MeSH
• stadia vývoje MeSH
• Trematoda fyziologie   patogenita   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Helminth neuroinfections represent serious medical conditions, but the diversity of the host-parasite interplay within the nervous tissue often remains poorly understood, partially due to the lack of laboratory models. Here, we investigated the neuroinvasion of the mouse spinal cord by Trichobilharzia regenti (Schistosomatidae). Active migration of T. regenti schistosomula through the mouse spinal cord induced motor deficits in hindlimbs but did not affect the general locomotion or working memory. Histological examination of the infected spinal cord revealed eosinophilic meningomyelitis with eosinophil-rich infiltrates entrapping the schistosomula. Flow cytometry and transcriptomic analysis of the spinal cord confirmed massive activation of the host immune response. Of note, we recorded striking upregulation of the major histocompatibility complex II pathway and M2-associated markers, such as arginase or chitinase-like 3. Arginase also dominated the proteins found in the microdissected tissue from the close vicinity of the migrating schistosomula, which unselectively fed on the host nervous tissue. Next, we evaluated the pathological sequelae of T. regenti neuroinvasion. While no demyelination or blood-brain barrier alterations were noticed, our transcriptomic data revealed a remarkable disruption of neurophysiological functions not yet recorded in helminth neuroinfections. We also detected DNA fragmentation at the host-schistosomulum interface, but schistosomula antigens did not affect the viability of neurons and glial cells in vitro. Collectively, altered locomotion, significant disruption of neurophysiological functions, and strong M2 polarization were the most prominent features of T. regenti neuroinvasion, making it a promising candidate for further neuroinfection research. Indeed, understanding the diversity of pathogen-related neuroinflammatory processes is a prerequisite for developing better protective measures, treatment strategies, and diagnostic tools.

• MeSH
• arginasa metabolismus   MeSH
• biologické markery metabolismus   MeSH
• chemokiny metabolismus   MeSH
• eozinofily metabolismus   MeSH
• hlavní histokompatibilní komplex MeSH
• imunita MeSH
• infekce červy třídy Trematoda imunologie   metabolismus   patologie   MeSH
• interakce hostitele a parazita MeSH
• mícha parazitologie   MeSH
• modely nemocí na zvířatech MeSH
• myši inbrední C57BL MeSH
• myši MeSH
• neuroglie parazitologie   MeSH
• neurony parazitologie   MeSH
• Schistosomatidae imunologie   MeSH
• stanovení celkové genové exprese MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• arginasa MeSH
• biologické markery MeSH
• chemokiny MeSH

BACKGROUND: Avian schistosomes, the causative agents of human cercarial dermatitis (or swimmer's itch), die in mammals but the mechanisms responsible for parasite elimination are unknown. Here we examined the role of reactive nitrogen species, nitric oxide (NO) and peroxynitrite, in the immune response of mice experimentally infected with Trichobilharzia regenti, a model species of avian schistosomes remarkable for its neuropathogenicity. METHODS: Inducible NO synthase (iNOS) was localized by immunohistochemistry in the skin and the spinal cord of mice infected by T. regenti. The impact of iNOS inhibition by aminoguanidine on parasite burden and growth was then evaluated in vivo. The vulnerability of T. regenti schistosomula to NO and peroxynitrite was assessed in vitro by viability assays and electron microscopy. Additionally, the effect of NO on the activity of T. regenti peptidases was tested using a fluorogenic substrate. RESULTS: iNOS was detected around the parasites in the epidermis 8 h post-infection and also in the spinal cord 3 days post-infection (dpi). Inhibition of iNOS resulted in slower parasite growth 3 dpi, but the opposite effect was observed 7 dpi. At the latter time point, moderately increased parasite burden was also noticed in the spinal cord. In vitro, NO did not impair the parasites, but inhibited the activity of T. regenti cathepsins B1.1 and B2, the peptidases essential for parasite migration and digestion. Peroxynitrite severely damaged the surface tegument of the parasites and decreased their viability in vitro, but rather did not participate in parasite clearance in vivo. CONCLUSIONS: Reactive nitrogen species, specifically NO, do not directly kill T. regenti in mice. NO promotes the parasite growth soon after penetration (3 dpi), but prevents it later (7 dpi) when also suspends the parasite migration in the CNS. NO-related disruption of the parasite proteolytic machinery is partly responsible for this effect.

• Klíčová slova
• 3-Nitrotyrosine, Cathepsin B, Nitric oxide, Nitric oxide synthase, Peroxynitrite, Schistosomatidae, Trichobilharzia,
• MeSH
• centrální nervový systém parazitologie   MeSH
• guanidiny farmakologie   MeSH
• infekce červy třídy Trematoda farmakoterapie   MeSH
• kůže parazitologie   MeSH
• kyselina peroxydusitá farmakologie   MeSH
• lidé MeSH
• mícha parazitologie   MeSH
• myši MeSH
• oxid dusnatý farmakologie   MeSH
• proteasy účinky léků   metabolismus   MeSH
• proteiny červů účinky léků   metabolismus   MeSH
• ptáci parazitologie   MeSH
• Schistosoma účinky léků   růst a vývoj   patogenita   MeSH
• Schistosomatidae účinky léků   růst a vývoj   patogenita   MeSH
• schistosomóza farmakoterapie   MeSH
• synthasa oxidu dusnatého účinky léků   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• guanidiny MeSH
• kyselina peroxydusitá MeSH
• oxid dusnatý MeSH
• pimagedine MeSH Prohlížeč
• proteasy MeSH
• proteiny červů MeSH
• synthasa oxidu dusnatého MeSH

Schistosomula (the post-infective stages) of the neurotropic schistosome Trichobilharzia regenti possess multiple isoforms of cathepsin B1 peptidase (TrCB1.1-TrCB1.6) with involvement in nutrient digestion. The comparison of substrate preferences of TrCB1.1 and TrCB1.4 showed that TrCB1.4 had a very narrow substrate specificity and after processing it was less effective toward protein substrates when compared to TrCB1.1. Self-processing of both isoforms could be facilitated by sulfated polysaccharides due to a specific binding motif in the pro-sequence. Trans-activation by heterologous enzymes was also successfully employed. Expression profiling revealed a high level of transcription of genes encoding the enzymatically inactive paralogs TrCB1.5 and TrCB1.6. The transcription level of TrCB1.6 was comparable with that of TrCB1.1 and TrCB1.2, the most abundant active isoforms. Recombinant TrCB1.6wt, a wild type paralog with a Cys29-to-Gly substitution in the active site that renders the enzyme inactive, was processed by the active TrCB1 forms and by an asparaginyl endopeptidase. Although TrCB1.6wt lacked hydrolytic activity, endopeptidase, but not dipeptidase, activity could be restored by mutating Gly29 to Cys29. The lack of exopeptidase activity may be due to other mutations, such as His110-to-Asn in the occluding loop and Asp224-to-Gly in the main body of the mature TrCB1.6, which do not occur in the active isoforms TrCB1.1 and TrCB1.4 with exopeptidase activity. The catalytically active enzymes and the inactive TrCB1.6 paralog formed complexes with chicken cystatin, thus supporting experimentally the hypothesis that inactive paralogs could potentially regulate the activity of the active forms or protect them from being inhibited by host inhibitors. The effect on cell viability and nitric oxide production by selected immune cells observed for TrCB1.1 was not confirmed for TrCB1.6. We show here that the active isoforms of TrCB1 have different affinities for peptide substrates thereby facilitating diversity in protein-derived nutrition for the parasite. The inactive paralogs are unexpectedly highly expressed and one of them retains the ability to bind cystatins, likely due to specific mutations in the occluding loop and the enzyme body. This suggests a role in sequestration of inhibitors and protection of active cysteine peptidases.

• Klíčová slova
• cathepsin B, cystatin, helminth, occluding loop, peptidase, processing, schistosome, substrate specificity,
• MeSH
• astrocyty metabolismus   MeSH
• cystatiny metabolismus   MeSH
• hydrolýza MeSH
• izoenzymy metabolismus   MeSH
• kathepsin B chemie   genetika   metabolismus   MeSH
• makrofágy metabolismus   MeSH
• myši MeSH
• oxid dusnatý metabolismus   MeSH
• prekurzory enzymů metabolismus   MeSH
• proteolýza MeSH
• RAW 264.7 buňky MeSH
• rekombinantní proteiny metabolismus   MeSH
• Schistosomatidae enzymologie   patogenita   MeSH
• substituce aminokyselin MeSH
• substrátová specifita MeSH
• vazba proteinů MeSH
• viabilita buněk MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• cystatin, egg-white MeSH Prohlížeč
• cystatiny MeSH
• izoenzymy MeSH
• kathepsin B MeSH
• oxid dusnatý MeSH
• prekurzory enzymů MeSH
• rekombinantní proteiny MeSH