Biology subjects

Rohr, C. M.

Publications and source records attributed to Rohr, C. M..

6 recordsLinked to original sources

bioRxiv2026

Expression of TRPMPZQ in excitable cells and sensory structures throughout the Schistosoma mansoni lifecycle

Praziquantel (PZQ) is an essential medicine used to treat schistosomiasis and other infectious diseases caused by parasitic flatworms. The parasite target of PZQ is a transient receptor potential ion channel of the melastatin subfamily, TRPMPZQ. As little is currently known about the native role of TRPMPZQ in schistosomes, we developed and validated TRPMPZQ specific antibodies to immunolocalize TRPMPZQ across various S. mansoni life cycle stages (adult worms, juvenile worms, miracidia and cercariae). TRPMPZQ was expressed in muscle, nervous tissues, as well as various sensory structures on the surface of the parasite across all these life cycle stages. In adult male worms, TRPMPZQ positive neurons innervated the oral and ventral suckers as well as sensory papillae covering the head of the worm. TRPMPZQ was also present in papillae throughout the body, and within tubercles. In a S. mansoni strain selected in the laboratory for resistance to PZQ, reduced expression and immunostaining of TRPMPZQ was apparent. In immature worms, which can recover from PZQ exposure, TRPMPZQ expression was predominantly found within the musculature compared with the neuronal localization evident in adult worms. A developmental transition of TRPMPZQ from muscle to nervous tissues during schistosome maturation was also supported from single cell RNAseq data. Because muscle buffers Ca2+ transients more effectively than neurons, the transition of TRPMPZQ away from muscle during schistosome maturation may increase the sensitivity of adult male worms to PZQ.

microbiology↗

bioRxiv2025

TRPtracker: a community database for monitoring praziquantel sensitivity at TRPMPZQ variants

The anthelmintic praziquantel (PZQ) has been used for decades as the clinical therapy for schistosomiasis, and remains the only available drug. As a cheap and effective drug therapy for all human disease-causing Schistosoma species, usage of PZQ underpins mass drug administration strategies aimed at eliminating schistosomiasis as a public health problem by 2030. Concern over the potential emergence of resistance to PZQ is therefore warranted, as it would constitute a major threat to this approach. In terms of molecular adaptations conferring PZQ resistance, variation in the sequence and/or expression of the drug target is an obvious mechanism and should be a priority for surveillance efforts. The target of PZQ is a transient receptor potential ion channel, TRPMPZQ, which is established as a locus that regulates schistosome sensitivity to PZQ. Here, we describe the establishment of a community resource, TRPtracker, which coalesces data on TRPMPZQ natural variants together with measurements of individual variant sensitivity to PZQ. A compendium of laboratory-generated mutants in TRPMPZQ is also compiled in TRPtracker to map regions within TRPMPZQ critical for PZQ sensitivity. Aggregation of data from multiple research groups into TRPtracker permits rapid community-wide exchange of data, cataloguing which TRPMPZQ variants have been functionally profiled, where geographically these variants have been found, their frequency within populations and their potential impact on PZQ sensitivity.

microbiology↗

bioRxiv2023

Target-based discovery of a broad spectrum flukicide

Diseases caused by parasitic flatworms impart a considerable healthcare burden worldwide. Many of these diseases - for example, the parasitic blood fluke infection, schistosomiasis - are treated with the drug praziquantel (PZQ). However, PZQ is ineffective against disease caused by liver flukes from the genus Fasciola. This is due to a single amino acid change within the target of PZQ, a transient receptor potential ion channel (TRPMPZQ), in Fasciola species. Here we identify benzamidoquinazolinone analogs that are active against Fasciola TRPMPZQ. Structure-activity studies define an optimized ligand (BZQ) that caused protracted paralysis and damage to the protective tegument of these liver flukes. BZQ also retained activity against Schistosoma mansoni comparable to PZQ and was active against TRPMPZQ orthologs in all profiled species of parasitic fluke. This broad spectrum activity was manifest as BZQ adopts a pose within the binding pocket of TRPMPZQ dependent on a ubiquitously conserved residue. BZQ therefore acts as a universal activator of trematode TRPMPZQ and a first-in-class, broad spectrum flukicide.

microbiology↗

bioRxiv2023

Praziquantel activates a native cation current in Schistosoma mansoni

Praziquantel (PZQ), an anthelmintic drug discovered in the 1970s, is still used to treat schistosomiasis and various other infections caused by parasitic flatworms. PZQ causes a triad of phenotypic effects on schistosome worms - rapid depolarization, muscle contraction, and damage throughout the worm tegument. The molecular target mediating these effects has been intimated as a Ca2+-permeable ion channel, but native currents evoked by PZQ have not been reported in any schistosome cell type. The properties of the endogenous PZQ activated conductance therefore remain unknown. Here, invasive electrophysiology was used to probe for responses to PZQ from different locales in a living schistosome worm. No direct response was seen in tegument-derived vesicles, or from the sub-tegumental muscle layer despite the presence of voltage-operated currents. However, PZQ rapidly triggered a sustained, non-selective cation current in recordings from neuronal tissue, targeting both the anterior ganglion and the main longitudinal nerve cord. The biophysical signature of this PZQ-evoked current resolved at single channel resolution matched that of a transient receptor potential ion channel named TRPMPZQ, recently proposed as the molecular target of PZQ. The endogenous PZQ-evoked current was also inhibited by a validated TRPMPZQ antagonist. PZQ therefore is a neuroactive anthelmintic, effecting a robust, depolarization through ion channels with the characteristics of TRPMPZQ. Key Findings / Scope StatementO_LIResponses to the anthelmintic drug, praziquantel (PZQ), were examined using invasive electrophysiology in a living schistosome worm. C_LIO_LIPZQ evoked a cation current in recordings from neuronal tissue C_LIO_LIThe biophysical and pharmacological characteristics of the native PZQ current matched the properties of TRPMPZQ. C_LI

pharmacology and toxicology↗

bioRxiv2021

Genetic analysis of praziquantel resistance in schistosome parasites implicates a Transient Receptor Potential channel

Mass treatment with praziquantel (PZQ) monotherapy is the mainstay for schistosomiasis treatment. This drug shows imperfect cure rates in the field and parasites showing reduced PZQ response can be selected in the laboratory, but the extent of resistance in Schistosoma mansoni populations is unknown. We examined the genetic basis of variation in PZQ response in a S. mansoni population (SmLE-PZQ-R) selected with PZQ in the laboratory: 35% of these worms survive high dose (73 {micro}g/mL) PZQ treatment. We used genome wide association to map loci underlying PZQ response. The major chr. 3 peak contains a transient receptor potential (Sm.TRPMPZQ) channel (Smp_246790), activated by nanomolar concentrations of PZQ. PZQ response shows recessive inheritance and marker-assisted selection of parasites at a single Sm.TRPMPZQ SNP enriched populations of PZQ-resistant (PZQ-ER) and sensitive (PZQ-ES) parasites showing >377 fold difference in PZQ response. The PZQ-ER parasites survived treatment in rodents better than PZQ-ES. Resistant parasites show 2.25-fold lower expression of Sm.TRPMPZQ than sensitive parasites. Specific chemical blockers of Sm.TRPMPZQ enhanced PZQ resistance, while Sm.TRPMPZQ activators increased sensitivity. A single SNP in Sm.TRPMPZQ differentiated PZQ-ER and PZQ-ES lines, but mutagenesis showed this was not involved in PZQ-response, suggesting linked regulatory changes. We surveyed Sm.TRPMPZQ sequence variation in 259 parasites from the New and Old World revealing one nonsense mutation that results in a truncated protein with no PZQ-binding site. Our results demonstrate that Sm.TRPMPZQ underlies variation in PZQ response in S. mansoni and provides an approach for monitoring emerging PZQ-resistance alleles in schistosome elimination programs. One Sentence SummaryA transient receptor potential channel determines variation in praziquantel-response in Schistosoma mansoni.

genetics↗

bioRxiv2020

Schistosomes alter expression of immunomodulatory gene products following in vivo praziquantel exposure

Control of the neglected tropical disease schistosomiasis relies almost entirely on praziquantel (PZQ) monotherapy. How PZQ clears parasite infections remains poorly understood. Many studies have examined the effects of PZQ on worms cultured in vitro, observing outcomes such as muscle contraction. However, conditions worms are exposed to in vivo may vary considerably from in vitro experiments given the short half-life of PZQ and the importance of host immune system engagement for drug efficacy in animal models. Here, we investigated the effects of in vivo PZQ exposure on Schistosoma mansoni. Measurement of pro-apoptotic caspase activation revealed that worm death occurs only after parasites shift from the mesenteric vasculature to the liver, peaking 24 hours after drug treatment. This indicates that PZQ is not directly schistocidal, since the drugs half-life is [~]2 hours, and focuses attention on parasite interactions with the host immune system following the shift of worms to the liver. RNA-Seq of worms harvested from mouse livers following sub-lethal PZQ treatment revealed drug-evoked changes in the expression of putative immunomodulatory and anticoagulant gene products. Several of these gene products localized to the schistosome esophagus and may be secreted into the host circulation. These include several Kunitz-type protease inhibitors, which are also found in the secretomes of other blood feeding animals. These transcriptional changes may reflect mechanisms of parasite immune-evasion in response to chemotherapy, given the role of complement-mediated attack and the host innate / humoral immune response in parasite elimination. One of these isoforms, SmKI-1, has been shown to exhibit immunomodulatory and anti-coagulant properties. These data provide insight into the effect of in vivo PZQ exposure on S. mansoni, and the transcriptional response of parasites to the stress of chemotherapy. Author SummaryThe disease schistosomiasis is caused by parasitic worms that live within the circulatory system. While this disease infects over 200 million people worldwide, treatment relies almost entirely on one drug, praziquantel, whose mechanism is poorly understood. In this study, we analyzed the effects of praziquantel treatment on the gene expression of parasites harvested from mice treated with praziquantel chemotherapy. Despite the rapid action of the drug on worms in vitro, we found that key outcomes in vivo (measurement of cell death and changes in gene expression) occurred relatively late (12+ hours after drug administration). We found that worms increased the expression of immunomodulatory gene products in response to praziquantel, including a Kunitz-type protease inhibitor that localized to the worm esophagus and may be secreted to the external host environment. These are an intriguing class of proteins, because they display anti-coagulant and immunomodulatory properties. Up-regulation of these gene products may reflect a parasite mechanism of immune-evasion in response to chemotherapy. This research provides insight into the mechanism of praziquantel by observing the effect of this drug on worms within the context of the host immune system.

pharmacology and toxicology↗