Tomáš Macháček

Models of maternal immune activation (MIA) often lead to parvalbumin-positive (PV+) interneuron deficits and behavioral alterations resembling autism or schizophrenia. We aimed to characterize the effects of MIA in PV-Cre Long-Evans rats. Pregnant dams received 8 lipopolysaccharide injections (1 mg/kg), on alternating days, starting with gestational day 7. The offspring behavior was tested from postnatal day 5 to adulthood, with tasks assessing motor development, anxiety, exploration, social behavior and sensorimotor gating. Morphological changes in the brain, density of PV+ interneurons and perineuronal nets in the prefrontal cortex, as well as the quantity of PV protein were measured at selected timepoints. We found that MIA in PV-Cre Long-Evans rats failed to elicit the expected schizophrenia- or autism-like deficits. Decrease in PV protein in the prefrontal cortex was present without corresponding decrement of PV+ interneurons, with a paradoxical increase in perineuronal net counts. PV-Cre Long-Evans rat line reacts to the MIA protocol very differently than Wistar rats in previously published studies and is suboptimal for studies of schizophrenia- or autism-like behavioral deficits. Genetic background seems to be an important factor for the outcome in MIA rodent models.

Introduction: Schistosoma mansoni eggs are the central drivers of schistosomiasis pathology and transmission, yet the proteins they release within host tissues remain poorly defined due to limitations of conventional in vitro approaches. Here, we provide the first in situ characterization of egg-derived proteins present in host tissues. Methods: Using laser microdissection, we selectively isolated periovular granuloma microenvironments from the livers and small intestines of infected mice during the acute and chronic phases of infection, followed by high-resolution mass spectrometry. Results: Across all samples, we identified a conserved core set of 149 parasite proteins, representing a true in vivo egg excretory/secretory repertoire. Egg-associated protein profiles varied markedly by organ and infection phase. In the liver, acute infection was characterized by a richer and more abundant repertoire of immunomodulators (including omega-1 and IPSE), proteases, protease inhibitors, antioxidant proteins, and micro-exon gene and venom allergen-like proteins, whereas chronic liver granulomas showed a reduced and altered profile. In contrast, intestinal granulomas exhibited fewer qualitative changes between phases and a more uniform protein composition over time, despite an overall decline in protein detectability. These patterns likely reflect fundamental differences in egg fate and tissue context, as hepatic eggs remain permanently trapped whereas intestinal eggs transit out of the host. Conclusion: This study provides the first in situ snapshot of schistosome egg-derived proteins within host tissues, revises assumptions about intestinal granuloma chronicity, and defines core and context-dependent egg proteins that are likely to shape granuloma biology, host modulation, and parasite transmission.

Background: The larvae of Mesocestoides corti have been previously shown to abrogate the growth and metastasis of the highly aggressive B16F10 melanoma in mice. In order to investigate the potential ways in which this effect is mediated, we present, to the best of our knowledge, the most comprehensive analyses of M. corti larval molecular data so far, while listing and exploring various potentially immunomodulatory molecules found therein. We show expression and protein abundance in larvae under in vivo and in vitro conditions. A promising ortholog, M. corti Kunitz-type chymotrypsin-specific inhibitor 1 (McKI-C1) of a known cancer-suppressive Kunitz protein from Echinococcus granulosus is also tested, both in vitro and in vivo. Methods: In order to explore the potential effector mechanisms and molecules behind its cancer-suppressive capabilities, we analyzed the M. corti larval transcriptome in the C57BL/6J and ICR mouse strains, as well as in vitro. The proteomic profiles of whole homogenate and excretory-secretory products of tetrathyridia were analyzed by nano-shotgun liquid chromatography with tandem mass spectrometry and thoroughly annotated. A Kunitz protein candidate (McKI-C1) was recombinantly expressed in Escherichia coli , biochemically characterized, and functionally tested for its anti-cancer effect with mouse melanoma B16F10 cells and mouse ovarian carcinoma ID8 cells. Results: We present, to the best of our knowledge, the most extensive list of experimentally verified M. corti protein products. Many proteins potentially responsible for this tapeworm’s immune-related cancer-suppressive abilities and immunomodulation were found within its proteome and transcriptome. These include numerous members of the superfamily of cysteine-rich secretory proteins, such as glioma pathogenesis-related-like proteins, and Kunitz-domain proteins. Functional tests of recombinant McKI-C1 performed both in vitro and in vivo did not confirm its expected tumor-suppressing properties. Therefore, the exact effectors of this tapeworm’s likely immune-mediated anti-tumor capabilities need to be examined in further studies. Conclusions: The transcriptomic and proteomic analysis of M. corti larvae carried out in the present study produced an extensive list of promising immunomodulatory or cancer-suppressive molecules. While the molecule chosen for analysis in the present study, McKI-C1, did not show any effect in vitro or in vivo, the immunomodulatory or cancer-suppressive potential of the other experimentally verified molecules remains of interest.

Background: Cercarial dermatitis (CD), or swimmer’s itch, is a water-borne allergic skin reaction caused by the penetration of the larval stages of bird schistosomes (cercariae) into the skin. Members of the genus Trichobilharzia are the primary causative agents of CD worldwide. Due to the increasing number of cases, CD is regarded as a (re)emerging disease. Outbreaks in recreational waters can significantly impact public health and local economies. Environmental monitoring of Trichobilharzia is crucial for outbreak prediction and public health management. However, conventional methods, such as cercarial shedding and snail dissections, are labour-intensive and lack sensitivity. To overcome these limitations, we present a molecular toolkit that combines loop-mediated isothermal amplification (LAMP), quantitative polymerase chain reaction (qPCR), and multiplex PCR for rapid, sensitive, and accurate detection and identification of Trichobilharzia spp. from various biological samples. Methods: Tricho-LAMP and Tricho-qPCR were designed and optimised for Trichobilharzia DNA detection. A multiplex PCR assay was also developed and optimised to identify the three main species causing CD in Europe (Trichobilharzia franki, T. szidati, and T. regenti). Results: Tricho-LAMP specifically detected T. regenti and T. franki at 10⁻³ ng, and T. szidati at 10⁻² ng per reaction with genomic DNA. Using gBlocks synthetic DNA, Tricho-LAMP achieved 100% amplification at 10,000 copies and 85% amplification at 1000 copies, with decreasing success at lower concentrations. Tricho-qPCR showed the highest sensitivity, detecting all species down to 10⁻⁴ ng per reaction and showing a limit of detection at 10 copies of synthetic DNA in the reaction. Multiplex PCR allowed reliable species differentiation via gel electrophoresis of the PCR products, but the assay had the lowest sensitivity. Conclusions: We provide a molecular toolkit consisting of LAMP, qPCR, and multiplex PCR. By exhibiting high sensitivity, Tricho-LAMP and Tricho-qPCR assays are potentially suitable for environmental DNA (eDNA)-based environmental monitoring of bird schistosomes, by both researchers and public health authorities. Multiplex PCR can be used for species determination without the need for further sequencing. Graphical

The potential link between the infections and the development of Alzheimer’s disease (AD) has led to speculations about the role of various pathogens in triggering amyloid-β (Aβ) overproduction, possibly leading to AD onset. The globally distributed dog roundworm Toxocara canis was suggested to be a suitable candidate due to neurotropism of the larvae and infection chronicity. This study investigated whether chronic T. canis infection induces AD-like pathology in mice and whether Aβ is toxic to T. canis. BALB/c and APP/PS1 transgenic mice, which overproduce Aβ, were infected with T. canis L3 larvae and monitored for larval burden, Aβ accumulation, and behavioral changes. In vitro tests of recombinant Aβ toxicity against the larvae were also performed. Despite the presence of T. canis larvae in the central nervous system 8 and 16 weeks post-infection, no significant increase in Aβ concentration or AD-related behavioral alterations were observed. Aβ was detected on the surface and within the intestines of T. canis larvae, but in vitro exposure to recombinant Aβ did not affect larval viability or morphology. Our findings suggest that T. canis infection does not trigger AD-like pathology in mice, and Aβ does not act as an antiparasitic agent. This challenges the emerging hypothesis that chronic neurotoxocarosis infections may contribute to AD development.

Skin uses interdependent cellular networks for barrier integrity and host immunity, but most underlying mechanisms remain obscure. Herein, we demonstrate that the human parasitic helminth Schistosoma mansoni inhibited pruritus evoked by itch-sensing afferents bearing the Mas-related G-protein-coupled receptor A3 (MrgprA3) in mice. MrgprA3 neurons controlled interleukin (IL)-17⁺ γδ T cell expansion, epidermal hyperplasia and host resistance against S. mansoni through shaping cytokine expression in cutaneous antigen-presenting cells. MrgprA3 neuron activation downregulated IL-33 but induced IL-1β and tumor necrosis factor in macrophages and type 2 conventional dendritic cells partially through the neuropeptide calcitonin gene-related peptide. Macrophages exposed to MrgprA3-derived secretions or bearing cell-intrinsic IL-33 deletion showed increased chromatin accessibility at multiple inflammatory cytokine loci, promoting IL-17/IL-23-dependent changes to the epidermis and anti-helminth resistance. This study reveals a previously unrecognized intercellular communication mechanism wherein itch-inducing MrgprA3 neurons initiate host immunity against skin-invasive parasites by directing cytokine expression patterns in myeloid antigen-presenting cell subsets.

The eggs of the blood fluke Schistosoma mansoni are the main cause of the clinical manifestations of chronic schistosomiasis. After laying, the egg “winners” attach to the endothelium of the mesenteric vein and, after a period of development, induce the growth of a small granuloma, which facilitates their passage to the intestinal lumen. Egg “losers” carried by the bloodstream to non-specific tissues also undergo full development and induce large granuloma formation, but their life ends there. Although these trapped eggs represent a dead end in the parasite life cycle, the vast majority of studies attempting to describe the biology of the S. mansoni eggs have studied these liver-trapped “losers” instead of migrating intestinal “winners”. This raises the fundamental question of how these eggs differ. With robust comparative transcriptomic analysis performed on S. mansoni eggs isolated 7 weeks post infection, we show that gene expression is critically dependent on tissue localization, both in the early and late stages of development. While mitochondrial genes and venom allergen-like proteins are significantly upregulated in mature intestinal eggs, well-described egg immunomodulators IPSE/alpha-1 and omega-1, together with micro-exon genes, are predominantly expressed in liver eggs. In addition, several proteases and protease inhibitors previously implicated in egg-host interactions display clear tissue-specific gene expression patterns. These major differences in gene expression could be then reflected in the observed different ability of liver and intestinal soluble egg antigens to elicit host immune responses and in the shorter viability of miracidia hatched from liver eggs. Our comparative analysis provides a new perspective on the biology of parasite’s eggs in the context of their development and tissue localization. These findings could contribute to a broader and more accurate understanding of parasite eggs interactions with the host, which have historically been often restricted to liver eggs and sometimes inaccurately generalized.