Dynamic relationship among extracellular matrix and body wall cells in Hirudo verbana morphogenesis

A great bulk of recent experimental evidence suggests the key role of the complex crosstalk between the extracellular matrix (ECM) and the cellular component of tissues during morphogenesis and embryogenesis. In particular, remodeling of the ECM and of its physical interactions pattern with surrounding cells represent two crucial processes that might be involved in muscle development. However, little information is available on this topic, especially on invertebrate species. To obtain new insights on how tuning the ECM microenvironment might drive cellular fate during embryonic development, we used the invertebrate medicinal leech Hirudo verbana as a valuable experimental model, due to its simple anatomy and the recapitulation of many aspects of the basic biological processes of vertebrates. Our previous studies on leech post-embryonic development have already shown the pivotal role of ECM changes during the growth of the body wall and the role of Yes-associated protein 1 (YAP1) in mechanotransduction. Here, we suggest that the interactions between stromal cell telocytes and ECM might be crucial in driving the organization of muscle layers during embryogenesis. Furthermore, we propose a possible role of the pleiotropic enzyme HvRNASET2 as a possible modulator of collagen deposition and ECM remodeling not only during regenerative processes (as previously demonstrated) but also in embryogenesis.

Leech extract alleviates idiopathic pulmonary fibrosis by TGF-β1/Smad3 signaling pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Leech, as a traditional Chinese medicine for the treatment of blood circulation and blood stasis, was also widely used to cure pulmonary fibrosis in China. In clinical practice, some traditional Chinese medicine preparation such as Shui Zhi Xuan Bi Hua Xian Tang and Shui Zhi Tong Luo Capsule composed of leech, could improve the clinical symptoms and pulmonary function in patients with idiopathic pulmonary fibrosis (IPF). However, the material basis of the leech in the treatment of IPF were not yet clear.

AIM OF THE STUDY

Screen out the components of leech that have the anti-pulmonary fibrosis effects, and further explore the therapeutic mechanism of the active components.

MATERIALS AND METHODS

In this study, the different molecular weight components of leech extract samples were prepared using the semi-permeable membranes with different pore sizes. The therapeutic effects of the leech extract groups with molecular weight greater than 10 KDa (>10 KDa group), between 3 KDa and 10 KDa (3-10 KDa group), and less than 3 KDa (<3 KDa group) on pulmonary fibrosis were firstly investigated by cell proliferation and cytotoxicity assay (MTT), cell wound healing assay, immunofluorescence staining (IF) and Western blot (WB) assay through the TGF-β1-induced fibroblast cell model. Then bleomycin-induced pulmonary fibrosis (BML-induced PF) mouse model was constructed to investigate the pharmacological activities of the active component group of leech extract in vivo. Pathological changes of the mouse lung were observed by hematoxylin-eosin staining (H&E) and Masson's trichrome staining (Masson). The hydroxyproline (HYP) content of lung tissues was quantified by HYP detection kit. The levels of extracellular matrix-related fibronectin (FN) and collagen type Ⅰ (Collagen Ⅰ), pyruvate kinase M2 (PKM2) monomer and Smad7 protein were determined via WB method. PKM2 and Smad7 protein were further characterized by IF assays.

RESULTS

Using TGF-β1-induced HFL1 cell line as a PF cell model, the in vitro results demonstrated that the >10 KDa group could significantly inhibited the cell proliferation and migration, downregulated the expression level of cytoskeletal protein vimentin and α-smooth muscle actin (α-SMA), and reduced the deposition of FN and Collagen Ⅰ. In the BML-induced PF mouse model, the >10 KDa group significantly reduced the content of HYP, downregulated the expression levels of FN and Collagen Ⅰ in lung tissues, and delayed the pathological changes of lung tissue structure. The results of WB and IF assays further indicated that the >10 KDa group could up-regulate the expression level of PKM2 monomer and Smad7 protein in the cellular level, thereby delaying the progression of pulmonary fibrosis.

CONCLUSIONS

Our study revealed that the >10 KDa group was the main material basis of the leech extract that inhibited pulmonary fibrosis through TGF-β1/Smad3 signaling pathway.

Biomechanics of transduction by mechanosensory cilia for prey detection in aquatic organisms

Surface-feeding aquatic animals navigate towards the source of water disturbances and must differentiate prey from other environmental stimuli. Medicinal leeches locate prey, in part, using a distribution of mechanosensory hairs along their body that deflect under fluid flow. Leech's behavioral responses to surface wave temporal frequency are well documented. However, a surface wave's temporal frequency depends on many underlying environmental and fluid properties that vary substantially in natural habitats (e.g., water depth, temperature). The impact of these variables on neural response and behavior is unknown. Here, we developed a physics-based leech mechanosensor model to examine the impact of environmental and fluid properties on neural response. Our model used the physical properties of a leech cilium and was verified against existing behavioral and electrophysiological data. The model's peak response occurred with waves where the effects of gravity and surface tension were nearly equal (i.e., the phase velocity minimum). This suggests that preferred stimuli are related to the interaction between fundamental properties of the surrounding medium and the mechanical properties of the sensor. This interaction likely tunes the sensor to detect the nondispersive components of the signal, filtering out irrelevant ambient stimuli, and may be a general property of cilia across the animal kingdom.

Antithrombotic pharmacodynamics and metabolomics study in raw and processed products of Whitmania pigra Whitman

Objective

As a traditional Chinese medicine, leech has obvious pharmacological activities in anticoagulantion and antithrombosis. Whitmania pigra Whitman (WP) is the most commonly used leech in the Chinese market. It is often used in clinical applications after high-temperature processing by talcum powder to remove the fishy taste and facilitate crushing. The anticoagulant and thrombolytic active ingredients are protein and polypeptide, which may denaturate and lose activity after high-temperature processing. The rationality of its processing has been questioned in recent years. This study aims to investigate the effect of talcum powder scalding on the antithrombotic activity of WP in vivo and to discuss its pharmacodynamic mechanism in vivo.

Methods

Raw and talcum-powdered processed WP were administered intragastrically for 14 days, and carrageenan was injected intraperitoneally to prepare a mouse model of tail vein thrombosis. The incidence rate of tail vein thrombosis and the thrombus area under pathological tissue sections were calculated to evaluate the antithrombotic effect between raw and processed WP. Non-targeted metabolomics was conducted using UPLC-Q-TOF/MS technology to analyze the changes of small molecule metabolites in the body after administration of WP.

Results

After intragastric administration, both the raw product and the processed product of WP could inhibit the thrombosis induced by carrageenan, and the processed product had a more apparent antithrombotic effect than the raw product. The administration of WP could regulate the changes of some small molecular metabolites, such as amino acids, lipids, and steroids, in Sphingolipid metabolism and Glycerophospholipid metabolism.

Conclusions

Based on the results of pharmacodynamics and metabolomics, processed WP will not reduce the antithrombotic activity of WP. This study provided a scientific basis for the rational use of leeches.

Efficacy and potential mechanism of atherosclerosis prevention by the active components of leech based on network pharmacology combined with animal experiments

Introduction

Leeches are flesh-eating and bloodsucking parasitic worms. They are being used as a traditional Chinese medicine for centuries in activating blood and dissolving statis, dreging the meridims and tick. Hirudin, an active peptide product present in leech, has blood anticoagulant property and can assist in the treatment of thrombosis and diseases related to blood circulation. The efficacy and potential mechanism of action of leeches in such diseases should be further explored.

Materials and methods

First, network pharmacology was used to screen the predicted potential targets of the active constituents of leech and AS. The common targets of the active constituents of leech and AS were obtained using Venn diagram. Further, the drug-active-constituent-target network diagram, protein-protein interaction, and GO and KEGG pathway enrichment analyses were used to construct the active-constituent-AS target-pathway network diagram. Subsequently, the protein-drug molecule docking model was drawn. Finally, the results of network pharmacology were validated using a mouse model of AS.

Results

In total, 34 active constituents of leech and 1172 AS-related gene targets were selected, took the drug action targets and potential disease targets to get the common targets, and took the top 10 of degree value as the main active constituents for the treatment of atherosclerosis. There were 89 common targets and 12 core targets. The main targets included MAPK, EGFR, PIK3CB, etc. Potential regulatory pathways included cancer pathways, EGFR tyrosine kinase inhibitor resistance, Rap1 signaling pathway, PPAR signaling pathway, PI3K-Akt signaling pathway, C-type lectin receptor signaling pathway, and AGE-RAGE signaling pathway in diabetic complications. Animal experiments using mouse model of AS confirmed that AS plaques were smaller after treatment with leeches. SRC level was measured using western blotting. Expression of SRC in myocardial tissue was remarkably lower in the mice treated with leech than in the mice from model group fed on high-fat chow.

Conclusions

To the best of our knowledge, this is the first study to explore the mechanism of action of the active components of leech in AS prevention. The active components of leeches play a coordinated role in preventing AS through multicomponent, multitarget, and multichannel mechanism of action related to inflammatory response, oxidative stress, and lipid metabolism. This study provided a reference for subsequent cellular and animal experiments.

First description study on molecular characterization of Hemiclepsis khankiana (Hirudinea: Glossiphoniidae) in China

BACKGROUND

Leeches are an integral component of aquatic biocenosis and can be found in a wide range of ecosystems such as freshwater, saltwater, flowing, and still-water ecosystems. It especially plays an important role in the freshwater benthic community and is an important part of the food web. In this study, a leech species was found in the mantle cavity of wild freshwater mussels in Zigong City, Sichuan Province, China, and its identity was determined through morphological analysis and molecular biological analysis.

RESULTS

The leech is Hemiclepsis khankiana, a new species of Hemiclepsis that has been discovered in Russia in recent years. Through morphological analysis, the current survey observed that the morphological characteristics of Hemiclepsis khankiana eyespots were significantly different from the first reported description. The first pair of eyespots on the leech were separated and clear, while it had been reduced to unclear shadows in the previous report. The phylogenetic tree based on the COI gene showed that the COI gene sequence obtained in this study was in the same evolutionary branch as Hemiclepsis khankiana (MN295420, MN295421). Genetically, it was most closely related to Hemiclepsis kasmiana (mean COI p-distance = 3.98%).

CONCLUSIONS

The current study reported on the new distribution range of Hemiclepsis khankiana, which was initially discovered in China. This study indicates that the distribution range of the leech species has expanded, laying a foundation for further studies in China.

Chromosome-level Dinobdella ferox genome provided a molecular model for its specific parasitism

BACKGROUND

Dinobdella ferox is the most frequently reported leech species parasitizing the mammalian nasal cavity. However, the molecular mechanism of this special parasitic behavior has remained largely unknown.

METHODS

PacBio long-read sequencing, next-generation sequencing (NGS), and Hi-C sequencing were employed in this study to generate a novel genome of D. ferox, which was annotated with strong certainty using bioinformatics methods. The phylogenetic and genomic alterations of D. ferox were then studied extensively alongside the genomes of other closely related species. The obligatory parasitism mechanism of D. ferox was investigated using RNA-seq and proteomics data.

RESULTS

PacBio long-read sequencing and NGS yielded an assembly of 228 Mb and contig N50 of 2.16 Mb. Along Hi-C sequencing, 96% of the sequences were anchored to nine linkage groups and a high-quality chromosome-level genome was generated. The completed genome included 19,242 protein-coding genes. For elucidating the molecular mechanism of nasal parasitism, transcriptome data were acquired from the digestive tract and front/rear ends of D. ferox. Examining secretory proteins in D. ferox saliva helped to identify intimate connections between these proteins and membrane proteins in nasal epithelial cells. These interacting proteins played important roles in extracellular matrix (ECM)-receptor interaction, tight junction, focal adhesion, and adherens junction. The interaction between D. ferox and mammalian nasal epithelial cells included three major steps of pattern recognition, mucin connection and breakdown, and repair of ECM. The remodeling of ECM between epithelial cells of the nasal mucosa and epithelial cells of D. ferox may produce a stable adhesion environment for parasitism.

CONCLUSIONS

Our study represents the first-ever attempt to propose a molecular model for specific parasitism. This molecular model may serve as a practical reference for parasitism models of other species and a theoretical foundation for a molecular process of parasitism.

The pattern of stability of African swine fever virus in leeches

African swine fever virus (ASFV) can accumulate and survive in leeches for a long time. The reasons for the survival of ASFV in leeches are not entirely clear. Here, we elucidate the virus survival pathway in infected leeches. One of the questions reported previously is addressed in this article. How the virus concentration in the body of the leech is equal to or higher than in the water infected with ASFV? Examination of blood swallowed by leeches reveals that the blood cells retain their morphological characteristics for several weeks. It can explain the long-term persistence of the high levels of ASFV in the leeches that ingested ASFV-infected pig blood. qRT-PCR assay showed the transcription of ASFV genes in infected leeches. However, the infectious particles of the virus measured by HADU haven't increased. Quantitative studies of the ASFV revealed a high content of both viral genes and infectious particles in the skin of leeches compared with other body parts. Electron microscopy analysis revealed the ability of the ASFV to effectively bind to the skin surface of the leeches, which explained the high concentrations of ASFV in the leeches' skin. A significant difference in the transcriptional activity between early and late viral genes indicates that the virus entered the initial stage of replication, but for some reason failed to complete it, which is typical of abortive infections.

Repetitive nociceptive stimulation elicits complex behavioral changes in Hirudo: evidence of arousal and motivational adaptations

Appropriate responses to real or potential damaging stimuli to the body (nociception) are critical to an animal's short- and long-term survival. The initial goal of this study was to examine habituation of withdrawal reflexes (whole-body and local shortening) to repeated mechanical nociceptive stimuli (needle pokes) in the medicinal leech, Hirudo verbana, and assess whether injury altered habituation to these nociceptive stimuli. While repeated needle pokes did reduce shortening in H. verbana, a second set of behavior changes was observed. Specifically, animals began to evade subsequent stimuli by either hiding their posterior sucker underneath adjacent body segments or engaging in locomotion (crawling). Animals differed in terms of how quickly they adopted evasion behaviors during repeated stimulation, exhibiting a multi-modal distribution for early, intermediate and late evaders. Prior injury had a profound effect on this transition, decreasing the time frame in which animals began to carry out evasion and increasing the magnitude of these evasion behaviors (more locomotory evasion). The data indicate the presence in Hirudo of a complex and adaptive defensive arousal process to avoid noxious stimuli that is influenced by differences in internal states, prior experience with injury of the stimulated areas, and possibly learning-based processes.

Characterization of the natural peptidome of four leeches by integrated proteogenomics and pseudotargeted peptidomics

Animal-derived drugs are an indispensable part of folk medicine worldwide. However, their chemical constituents are poorly approached, which leads to the low level of the quality standard system of animal-derived drugs and further causes a chaotic market. Natural peptides are ubiquitous throughout the organism, especially in animal-derived drugs. Thus, in this study, we used multi-source leeches, including Hirudo nipponica (HN), Whitmania pigra (WP), Whitmania acranulata (WA), and Poecilobdella manillensis (PM), as a model. A strategy integrating proteogenomics and novel pseudotargeted peptidomics was developed to characterize the natural peptide phenotype and screen for signature peptides of four leech species. First, natural peptides were sequenced against an in-house annotated protein database of closely related species constructed from RNA-seq data from the Sequence Read Archive (SRA) website, which is an open-sourced public archive resource. Second, a novel pseudotargeted peptidomics integrating peptide ion pair extraction and retention time transfer was established to achieve high coverage and quantitative accuracy of the natural peptides and to screen for signature peptides for species authentication. In all, 2323 natural peptides were identified from four leech species whose databases were poorly annotated. The strategy was shown to significantly improve peptide identification. In addition, 36 of 167 differential peptides screened by pseudotargeted proteomics were identified, and about one-third of them came from the leucine-rich repeat domain (LRR) proteins, which are widely distributed in organisms. Furthermore, six signature peptides were screened with good specificity and stability, and four of them were validated by synthetic standards. Finally, a dynamic multiple reaction monitoring (dMRM) method based on these signature peptides was established and revealed that one-half of the commercial samples and all of the Tongxinluo capsules were derived from WP. All in all, the strategy developed in this study was effective for natural peptide characterization and signature peptide screening, which could also be applied to other animal-derived drugs, especially for modelless species that are less studied in protein database annotation.

A Rare Cause of Epistaxis: Nasopharyngeal Leech Infestation

Leeches are rare cause of foreign body in airways. A 23-year-old male, experiencing epistaxis and difficulty in swallowing is presented. During nasopharyngoscopy, a moving leech was observed on the nasopharynx posterior wall in midline location, and removal of the leech was decided under general anaesthesia. The flexible nasopharyngoscopy was inserted, but removal was unsuccessful due to the leech's movements. Leeches are blood-sucking parasites, so neuromuscular blocking agent was given to prevent the movement. After administration, motion of the leech was lost and easily removed undamaged. In patients presenting with unexplained epistaxis, hemoptysis, dyspnea, and foreign body sensation in the airway, leech infestation should be included as the differential diagnosis and history of contact with stream water should be questioned. We concluded that use of low dose neuromuscular blocking agents facilitates the gentle removal, and could be necessary for successful management of removal of leech under general anaesthesia.

Approaches to studying injury-induced sensitization and the potential role of an endocannabinoid transmitter

Endocannabinoids are traditionally thought to have an analgesic effect. However, it has been shown that while endocannabinoids can depress nociceptive signaling, they can also enhance non-nociceptive signaling. Therefore, endocannabinoids have the potential to contribute to non-nociceptive sensitization after an injury. Using Hirudo verbana (the medicinal leech), a model of injury-induced sensitization was developed in which a reproducible piercing injury was delivered to the posterior sucker of Hirudo. Injury-induced changes in the non-nociceptive threshold of Hirudo were determined through testing with Von Frey filaments and changes in the response to nociceptive stimuli were tested by measuring the latency to withdraw to a nociceptive thermal stimulus (Hargreaves apparatus). To test the potential role of endocannabinoids in mediating injury-induced sensitization, animals were injected with tetrahydrolipstatin (THL), which inhibits synthesis of the endocannabinoid transmitter 2-arachidonoylglycerol (2-AG). Following injury, a significant decrease in the non-nociceptive response threshold (consistent with non-nociceptive sensitization) and a significant decrease in the response latency to nociceptive stimulation (consistent with nociceptive sensitization) were observed. In animals injected with THL, a decrease in non-nociceptive sensitization in injured animals was observed, but no effect on nociceptive sensitization was observed.

Ocular infestation by a juvenile leech, Myxobdella sinanensis in Japan

Purpose

The case of ocular infestation by a leech is rare. We reported that Myxobdella sinanensis infests conjunctiva.

Observations

A 5-year-old girl presented with blood clots in the inner corner of the left eye, and a history bloody eye discharge and bloody tears for 5 days. She was prescribed 0.5% levofloxacin ophthalmic drops for conjunctival damage. However, her parent watched a worm moving in her conjunctiva while taking a bath. She presented again the same day, and a worm was found in the left eye of the lower conjunctival fornix and was adsorbed to the inner corner. We removed a worm under eye drop anesthesia, the next day the patient had no symptoms. We captured the worm, and it was identified morphologically and genetically as Myxobdella sinanensis. This was the first case reported of Myxobdella sinanensis be infestation in a human.

Conclusions and Importance

The ecological trait of Myxobdella sinanensis still did not remain clear, so this case report was helpful to find out a life cycle of Myxobdella sinanensis. As the outdoor population continues to increase, the cases of human parasites such as leech are expected to increase. When a patient with bloody eye discharge and bloody tears presents, we should carefully examine the conjunctiva and ocular surfaces, and interview recent history of exposure to stream water.

Structure and cleavage pattern of a hyaluronate 3-glycanohydrolase in the glycoside hydrolase 79 family

Hyaluronidases have attracted a great deal of interest in the field of medicine due to their fundamental roles in the breakdown of hyaluronan. However, little is known about the catalytic mechanism of the hyaluronate 3-glycanohydrolases. Here, we report the crystal structure and cleavage pattern of a leech hyaluronidase (LHyal), which hydrolyzes the β-1,3-glycosidic bonds of hyaluronan. LHyal exhibits the typical structural features of glycoside hydrolase 79 family but contains a variable 'exo-pocket' loop where basic residues R102 and K103 are the structural determinants of hyaluronan binding. Through analysis of the hydrolysis of even- and odd-numbered hyaluronan oligosaccharides, we demonstrate that hexasaccharide is the shortest natural substrate, which can be cleaved from both the reducing and non-reducing ends to release disaccharides, and pentasaccharides are the smallest fragments for recognition and hydrolysis. These observations provide new insights into the degradation of hyaluronan and the evolutionary relationships of the GH79 family enzymes.

nov., found in the freshwater leech Hirudinaria manillensis

Leeches have long been considered potential vectors for the aquatic lineage of trypanosomes, while bloodsucking insects are generally considered as the vectors for the terrestrial lineage of trypanosomes. The freshwater leech, Hirudinaria manillensis, is a widely distributed species in southern China and could potentially act as the vector for trypanosomes. Prior to this study, no trypanosomes had been reported from this leech. However, in this study, leeches were collected from three different places in Guangdong province, China, and a large number of flagellates were isolated and successfully cultured in vitro. Based on morphology, these flagellates looked like a typical trypanosome species. Analysis was carried out on the molecular sequences of the 18S rRNA gene and the glycosomal glyceraldehyde-3-phosphate dehydrogenase (gGAPDH) gene. To our surprise, these flagellates were identified as likely to be a mammalian trypanosome belonging to the clade containing Trypanosoma (Megatrypanum) theileri but they are significantly different from the typical TthI and TthII stocks. Analyses of blood composition indicated that the source of the blood meal in these leeches was from the water buffalo (Bubalus bubalis). To further test if this flagellate from the freshwater leech was indeed a mammalian trypanosome, we transferred the trypanosomes cultured at 27-37 °C and they were able to successfully adapt to this mammalian body temperature, providing further supporting evidence. Due to the significant genetic differences from other related trypanosomes in the subgenus Megatrypanum, we propose that this flagellate, isolated from H. manillensis, is a new species and have named it Trypanosoma bubalisi. Our results indicate that freshwater leeches may be a potential vector of this new mammalian trypanosome.

Comparison of body wall histologic structure of two medicinal leeches Hirudo sulukii and Hirudo verbana (Hirudinida: Hirudinidae)

In this study, it was aimed to determine secretory cell types using histochemical properties of secretory cells and epidermis histology in the body wall of two medicinal leech species, Hirudo verbana and Hirudo sulukii. In addition, areas of epidermis epithelial cells, secretory cell types, and secretion areas of secretory cells stained with histochemical stains were statistically compared in both species. Epidermis is composed of single layer of cylindrical epithelium and secretory cells. The cuticle layer covers the epithelial layer. Some Type 1 cells within and close to the epidermis were determined as pear-shaped secretory cells. Type 2a and Type 2b secretory cells were found in large groups in the inner parts of the body wall, especially around muscles. While Type 1 cells were stained weakly with PAS and AB, Type 2b cells were stained darker than Type 2a cells. Statistical calculations showed that areas of epithelial and secretory cells were generally larger in H. sulukii than in H. verbana. Therefore, H. sulukii was thought to be a more resistant species compared to H. verbana. As secretion areas of secretory cells reacting with PAS and AB stains were generally larger in H. sulukii, it was concluded that mucus composition between the two species has different concentration.

Spectral responses across a dorsal-ventral array of dermal sensilla in the medicinal leech

How do animals use visual systems to extract specific features of a visual scene and respond appropriately? The medicinal leech, Hirudo verbana, is a predatory, quasi-amphibious annelid with a rich sensorium that is an excellent system in which to study how sensory cues are encoded, and how key features of visual images are mapped into the CNS. The leech visual system is broadly distributed over its entire body, consisting of five pairs of cephalic eyecups and seven segmentally iterated pairs of dermal sensilla in each mid-body segment. Leeches have been shown to respond behaviorally to both green and near ultraviolet light (UV, 365–375 nm). Here, we used electrophysiological techniques to show that spectral responses by dermal sensilla are mapped across the dorsal–ventral axis, such that the ventral sensilla respond strongly to UV light, while dorsal sensilla respond strongly to visible light, broadly tuned around green. These results establish how key features of visual information are initially encoded by spatial mapping of photo-response profiles of primary photoreceptors and provide insight into how these streams of information are presented to the CNS to inform behavioral responses.

The electrophysiological effects of cadmium on Retzius nerve cells of the leech Haemopis sanguisuga

Cadmium is considered one of the most toxic heavy metals which can cause cytotoxicity in multiple organs including the brain. Despite many studies over the past decades, the cellular and molecular mechanisms underlying its neurotoxicity remain unclear. The present study was designed to examine the acute effects of cadmium chloride (CdCl₂) on the electrical activity of the Retzius nerve cells of leech Haemopis sanguisuga using electrophysiological techniques. CdCl₂, in concentrations of 10-100 μM, produced a dose- and time-dependent depolarization of Retzius neurons, paralleled by an increase in firing frequency and action potential duration. To examine potential mechanisms, we studied the effects of cadmium on the outward potassium current upon depolarization using a point microelectrode voltage-clamp technique. Reduction of the fast, and partial inhibition of the slow outward current were observed after adding 50 and 100 μM CdCl₂ in the external fluid. The present results support the view that the effect of cadmium on the outward potassium channel may be a potential contributing mechanism for cadmium-induced neurotoxic damage. The proposed mechanism of cadmium action on the electrical properties of leech Retzius neurons might have broader significance concerning not only the leeches but vertebrate brains as well.

Leech in the Rectum Causing Lower GI Bleeding in a Four Years Old Child: A Case Report

Background

Leeches belong to a group of annelids of the class Hirudinea which are blood feeding ecto-parasites of humans, wild animals and domesticated animals. A leech can suck out as much blood as ten times its own weight. Leech can occur at different sites in humans commonly in the eyes, nasopharynx, larynx, urethra, and vagina and rarely in the rectum.

Case Details

This is a four years old male child who presented with painless, bright red rectal bleeding for two weeks. Heamatocrit was 9.2%. Leech was removed from the rectum by letting the child sit on a bucket of water. The patient was transfused, followed for 24 hours and discharged with iron sulphate syrup.

Conclusion

Leech infestation should be considered in the differential diagnosis of a child presenting with hematochezia.

Gene expression changes with tumor disease and leech parasitism in the juvenile green sea turtle skin transcriptome

Emerging infectious diseases are a major threat to biodiversity in the 21st century. Fibropapillomatosis (FP) is an epithelial tumor disease that affects immature and adult marine turtles worldwide, particularly green turtles (Chelonia mydas). We know little about the host factors contributing to FP susceptibility, in part because transcriptomic studies that compare transcript expression in turtles with and without FP are lacking. Here, we performed RNA-Seq on healthy skin tissue from immature C. mydas in the Indian River Lagoon, Florida, USA, comparing turtles (1) with and without FP and (2) with and without leech parasites, a putative vector of FP. We assembled a de novo C. mydas skin transcriptome to identify transcripts with significant differential expression (DE) across FP and leech categories. Significant DE transcripts were found across FP and leech comparisons, including 10 of the same transcripts with DE across both comparisons. Leech-positive individuals significantly upregulated different immune and viral interaction transcripts than did leech-negative individuals, including viral interaction transcripts associated with herpesvirus interactions. This finding strengthens the role of marine leeches as mechanical vectors of Chelonid herpesvirus 5 (ChHV5) which has been implicated as a causative agent of FP. FP-positive turtles upregulated several tumor progression and suppression transcripts relative to FP-negative turtles, which had no significant DE tumor progression transcripts. FP-positive turtles also upregulated significantly more protein interaction transcripts than FP-negative turtles. DE transcripts across leech comparisons showed no functional enrichment, whereas DE transcripts across FP comparisons showed some GO terms were enriched in FP-positive and FP negative turtles. Notably, only FP-negative turtles were enriched for GO terms involved in acquired and inflammatory immune gene regulation. Overall, our DE transcripts included several candidate genes that may play important roles in C. mydas resistance to or recovery from FP, highlighting that transcriptomics provides a promising venue to understand this impactful disease. Continued investigation of C. mydas responses to FP and leech affliction is imperative for species persistence and the conservation of marine ecosystems worldwide due to the essential role of sea turtles in ecosystem function and stability.

Affinity ultrafiltration and UPLC-HR-Orbitrap-MS based screening of thrombin-targeted small molecules with anticoagulation activity from Poecilobdella manillensis

This study aims to screen potential anticoagulant components from leeches, a representative animal-sourced traditional Chinese medicine using thrombin (THR)-targeted ultrafiltration combined with ultrahigh performance liquid chromatography and high-resolution Orbitrap mass spectrometry (UPLC-HR-Orbitrap-MS). As a result, five small molecules in leech extract were discovered to interact with THR for the first time. Among them, two new compounds were isolated and their structures were identified by IR, HR-MS and NMR data. Furthermore, their THR inhibitory activity was confirmed with IC₅₀ values of 4.74 and 8.31 μM, respectively. In addition, molecular docking analysis showed that the active (catalytic) site of THR might be the possible binding site of the two hits. Finally, reverse screening analysis indicated that LTA4-H, ACE and ALOX5AP were potential anticoagulant targets of the two new compounds. This study will broaden our understanding of the medicinal substance basis in leeches and further contribute to the discovery and development of clinical anticoagulant drugs from leeches.

Transcriptional profiling of identified neurons in leech

Background

While leeches in the genus Hirudo have long been models for neurobiology, the molecular underpinnings of nervous system structure and function in this group remain largely unknown. To begin to bridge this gap, we performed RNASeq on pools of identified neurons of the central nervous system (CNS): sensory T (touch), P (pressure) and N (nociception) neurons; neurosecretory Retzius cells; and ganglia from which these four cell types had been removed.

Results

Bioinformatic analyses identified 3565 putative genes whose expression differed significantly among the samples. These genes clustered into 9 groups which could be associated with one or more of the identified cell types. We verified predicted expression patterns through in situ hybridization on whole CNS ganglia, and found that orthologous genes were for the most part similarly expressed in a divergent leech genus, suggesting evolutionarily conserved roles for these genes. Transcriptional profiling allowed us to identify candidate phenotype-defining genes from expanded gene families. Thus, we identified one of eight hyperpolarization-activated cyclic-nucleotide gated (HCN) channels as a candidate for mediating the prominent sag current in P neurons, and found that one of five inositol triphosphate receptors (IP3Rs), representing a sub-family of IP3Rs absent from vertebrate genomes, is expressed with high specificity in T cells. We also identified one of two piezo genes, two of ~ 65 deg/enac genes, and one of at least 16 transient receptor potential (trp) genes as prime candidates for involvement in sensory transduction in the three distinct classes of leech mechanosensory neurons.

Conclusions

Our study defines distinct transcriptional profiles for four different neuronal types within the leech CNS, in addition to providing a second ganglionic transcriptome for the species. From these data we identified five gene families that may facilitate the sensory capabilities of these neurons, thus laying the basis for future work leveraging the strengths of the leech system to investigate the molecular processes underlying and linking mechanosensation, cell type specification, and behavior.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-021-07526-0.

Uncovering the mechanisms of leech and centipede granules in the treatment of diabetes mellitus-induced erectile dysfunction utilising network pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Diabetes mellitus-induced erectile dysfunction (DMED) is one of the most common complications of diabetes mellitus. Leech and centipede granules (LCG) have traditionally been used as blood-activating agents in various ethnomedicinal systems of East Asia, especially in China. It is often used to regulate bodily functions and considered as adjuvant therapy for promoting blood circulation, alleviating blood coagulation, activating meridians, and relieving stasis.

AIM OF THE STUDY

This study aimed to identify potential genes and mechanisms of LCG on DMED from the network pharmacological perspective.

MATERIALS AND METHODS

The active components of LCG were identified by UHPLC-Q-TOF-MS, TCMID, and the BATMAN-TCM databases, and the disease targets of DMED were obtained from the DisGeNET, CooLGeN, GeneCards databases. After identifying DMED targets of LCG, a protein-protein interaction (PPI) network was constructed. Hub genes and significant modules were identified via the MCODE plug-in of Cytoscape software. Then, significant signaling pathways of the modules were identified using the Metascape database. The probable interaction mode of compounds-hub genes is examined using Molecular Operating Environment (MOE) docking software. Besides, we investigated the effects and mechanisms of LCG on improving erectile function in the streptozotocin (STZ)-induced diabetic rats model.

RESULTS

Combined UHPLC-Q-TOF-MS analysis with network pharmacology study, 18 active compounds were selected for target prediction. There are 97 common target genes between LCG and DMED. Enrichment of the KEGG pathway mainly involves in the calcium signaling pathway, NF-kappa B signaling pathway, cGMP-PKG signaling pathway, HIF-1 signaling pathway, PI3K-Akt signaling pathway, and mTOR signaling pathway. Nine hub genes were regulated by LCG in DMED, including CXCL8, NOS3, CRH, TH, BDNF, DRD4, ACE, CNR1, and HTR1A. The results of molecular docking analysis showed that the tyrosin, ursolic acid, and L-Histidine has a relatively stable interaction with corresponding hub genes via generating hydrogen bonds, H-π, and π-π interactions. Significantly, the results in docking predicted a higher affinity of vardenafil to the hub genes compared to the tyrosin, ursolic acid, and L-Histidine. Furthermore, LCG increased the testosterone, erection frequency, the ratio of ICP and MAP, SOD, cGMP, cAMP as well as decreased the MDA, and AGEs expression levels. And, LCG ameliorated the histological change of penile tissues in DMED rats. Hence, LCG attenuates oxidative stress, increases NO production; For the mechanism exploration, LCG could significantly upregulate the mRNA and protein expression of CNR1, NOS3, CRH, TH, BDNF, and DRD4, whereas CXCL8, ACE, and HTR1A levels were significantly higher than those in the DMED group. Moreover, LCG activates the NO/cGMP/PKG pathway, PI3K/Akt/nNOS pathway, cAMP/PKA pathway, and inhibits the HIF-1α/mTOR pathway to improve erectile function.

CONCLUSIONS

Our results suggest that LCG maybe offer a new therapeutic basis for the treatment of DMED via altering the gene expression of involved metabolic pathways.

Effects of calcium-activated potassium channel modulators on afterhyperpolarizing potentials in identified motor and mechanosensory neurons of the medicinal leech

Calcium-activated potassium (K_Ca) channels contribute to multiple neuronal properties including spike frequency and afterhyperpolarizing potentials (AHPs). K_Ca channels are classified as K_Ca1.1, K_Ca2, or K_Ca3.1 based on single-channel conductance and pharmacology. Ca²⁺-dependent AHPs in vertebrates are categorized as fast, medium, or slow. Fast and medium AHPs are generated by K_Ca1.1 and K_Ca2 channels, respectively. The K_Ca subtype responsible for slow AHPs is unclear. Prolonged, Ca²⁺-dependent AHPs have been described in several leech neurons. Unfortunately, apamin and other K_Ca blockers often prove ineffective in the leech. An alternative approach is to utilize K_Ca modulators, which alter channel sensitivity to Ca²⁺. Vertebrate K_Ca2 channels are targeted selectively by the positive modulator CyPPA and the negative modulator NS8593. Here we show that AHPs in identified motor and mechanosensory leech neurons are enhanced by CyPPA and suppressed by NS8593. Our results indicate that K_Ca2 channels underlie prolonged AHPs in these neurons and suggest that K_Ca2 modulators may serve as effective tools to explore the role of K_Ca channels in leech physiology.

Mucosal hirudiniasis presenting as palatal mass: A case report and review of the literature

This paper presents the case of a 5-year-old child who presented with an 15-day history of a swelling over the palatal region and blood stained saliva. Intraoral examination showed dark red circular mass rising from the hard palate. Diagnosis of mucosal hirudiniasis have been made. The parasite has been extracted under local anesthesia using a blunt forceps, it has been identified as an adult Limnatis nilotica. Leech endoparasitism must be suspected in case of bleed from throat, dysphagia or any other related symptom, especially in pediatric patients who have been exposed to freshwater. Prevention remains the best medicine.

•

This paper presents the case of a 5-year-old child who presented with an 15-day history of a swelling over the palatal region and blood stained saliva.

•

Intraoral examination showed dark red circular mass rising from the hard palate. Diagnosis of mucosal hirudiniasis have been made.

•

Leech endoparasitism must be suspected in case of bleed from throat, dysphagia or any other related symptom, especially in pediatric patients who have been exposed to freshwater

Autophagy and its role in regeneration and remodeling within invertebrate

Background

Acting as a cellular cleaner by packaging and transporting defective proteins and organelles to lysosomes for breakdown, autophagic process is involved in the regulation of cell remodeling after cell damage or cell death in both vertebrate and invertebrate. In human, limitations on the regenerative capacity of specific tissues and organs make it difficult to recover from diseases. Comprehensive understanding on its mechanism within invertebrate have strong potential provide helpful information for challenging these diseases.

Method

In this study, recent findings on the autophagy function in three invertebrates including planarian, hydra and leech with remarkable regenerative ability were summarized. Furthermore, molecular phylogenetic analyses of DjATGs and HvATGs were performed on these three invertebrates compared to that of Saccharomyces cerevisiae, Caenorhabditis elegans, Drosophila melanogaster, Mus musculus and Homo sapiens.

Results

In comparison with Scerevisiae, C elegans, D melanogaster, M musculus and human, our analysis exhibits the following characteristics of autophagy and its function in regeneration within invertebrate. Phylogenetical analysis of ATGs revealed that most autophagy-related genes (ATGs) were highly similar to their homologs in other species, which indicates that autophagy is a highly conservative biological function in both vertebrate and invertebrate. Structurally, almost all the core amino acids necessary for the function of ATG8 in mammal were observed in invertebrate HvATG8s and DjATG8s. For instance, ubiquitin-like domain as a signature structure in each ATG8, was observed in all ATG8s in three invertebrates. Basically, autophagy plays a key role in the regulation of regeneration in planarian. DjATG8-2 and DjATG8-3 associated with mTOR signaling pathway are sophisticated in the invertebrate tissue/organ regeneration. Furthermore, autophagy is involved in the pathway of neutralization of toxic molecules input from blood digestion in the leech.

Conclusions

The recent investigations on autophagy in invertebrate including planarian, hydra and leech suggest that autophagy is evolutionally conserved from yeast to mammals. The fundamental role of its biological function in the invertebrate contributing to the regeneration and maintenance of cellular homeostasis in these three organisms could make tremendous information to confront life threatening diseases in human including cancers and cardiac disorders.

Adult ocular leech infestation

Ocular trauma accounts for a significant proportion of cases in any emergency eye outpatient department. There are very few cases reporting ocular injuries after leech exposure. Leeches are annelids belonging to the subclass Hirudinea; they dwell in fresh water and the sea and can be terrestrial. An oral sucker present anteriorly helps to attach to the host by releasing an anesthetic that prevents its recognition as a foreign body. Although many methods of leech removal have been proposed, its removal with forceps after instillation of local anesthetic remains a safe and effective method.

Pharmacological activity and NMR solution structure of the leech peptide HSTX-I

The role of voltage-gated sodium (Na_V) channels in pain perception is indisputable. Of particular interest as targets for the development of pain therapeutics are the tetrodotoxin-resistant isoforms Na_V1.8 and Na_V1.9, based on animal as well as human genetic studies linking these ion channel subtypes to the pathogenesis of pain. However, only a limited number of inhibitors selectively targeting these channels have been reported. HSTX-I is a peptide toxin identified from saliva of the leech Haemadipsa sylvestris. The native 23-residue peptide, stabilised by two disulfide bonds, has been reported to inhibit rat Na_V1.8 and mouse Na_V1.9 with low micromolar activity, and may therefore represent a scaffold for development of novel modulators with activity at human tetrodotoxin-resistant Na_V isoforms. We synthetically produced this hydrophobic peptide in high yield using a one-pot oxidation and single step purification and determined the three-dimensional solution structure of HSTX-I using NMR solution spectroscopy. However, in our hands, the synthetic HSTX-I displayed only very modest activity at human Na_V1.8 and Na_V1.9, and lacked analgesic efficacy in a murine model of inflammatory pain.

A novel thrombin inhibitory peptide discovered from leech using affinity chromatography combined with ultra-high performance liquid chromatography-high resolution mass spectroscopy

Thrombin (THR) inhibitors play an important role in the treatment of thrombotic diseases. This study established a THR-based bio-specific extraction coupled with affinity chromatography and ultra-high performance liquid chromatography-high resolution mass spectroscopy (UPLC-HR-MS) analysis method to screen and identify THR ligands in Leech. After evaluating the reliability of the screening method using positive control drug (hirudin), it was successfully used to screen the potential active constituents in leech. And a comprehensive analysis of the peptides in leech elution was performed by UPLC-HR-MS, a total of 34 peptides were identified. At the same time, anti-THR activity was explored and inferred by searching databases and published literature. As a result, six peptides were discovered to be potential active compounds in leech. Further, the six peptides were synthesized and in vitro enzymatic activity assay was performed. Finally, SYELPDGQVITIGNER was screened as an anti-THR peptide with an IC50 value of 255.75 µM and it was discovered for the first time from Whitmania pigra Whitman and Hirudo nipponica Whitman. The molecular docking study showed that THR inhibitory activity of the polypeptide was mainly attributed to the hydrogen bond interactions, van der Waals forces and electrostatic interactions interaction between polypeptide and THR. These results suggest that the polypeptide is a potential natural THR inhibitor that can be used as anticoagulant.

Netrin expressed by the ventral ectoderm lineage guides mesoderm migration in epibolic gastrulation of the leech

Netrin is a remarkably conserved midline landmark, serving as a chemotactic factor that organizes the bilateral neural architecture in the post-gastrula bilaterian embryos. Netrin signal also guides cell migration in many other neural and non-neural organogenesis events in later developmental stages but has never been found to participate in gastrulation - the earliest cell migration in metazoan embryogenesis. Here, we found that the netrin signaling molecules and their receptors are expressed during gastrulation of the leech Helobdella. Intriguingly, Hau-netrin-1 was expressed in the N lineage, which gives rise in part to the ventral midline of ectoderm, at the onset of gastrulation. We demonstrated that the N lineage is required for the entrance of mesoderm into the germinal band and that misexpression of Hau-netrin-1 in early gastrulation prevented mesoderm from entering the germinal band. Together, these results suggested that Hau-netrin-1 secreted by the N lineage guides mesoderm migration during germinal band assembly. Furthermore, ectopic expression of Hau-netrin-1 after the completion of germinal band assembly disrupted the epibolic migration of the germinal bands in a later stage of gastrulation. Thus, Hau-netrin-1 is likely involved in two distinct events in sequential stages of leech gastrulation: the assembly of germinal bands in early gastrulation and their epibolic migration in mid-gastrulation. Given that the leech netrin is expressed in the precursor cells of the ventral midline during gastrulation, we propose that a heterochronic change from the midline netrin expression had taken place in the evolution of a novel mode of gastrulation in the directly developing leech embryos.

A Rare Cause of Hemoptysis: Oropharyngeal Leech

We report the case of a 33-year-old patient who presented with dyspnea and hemoptysis due to an oropharyngeal leech infestation. The patient was a shepherd and his detailed history revealed that he had been drinking water from natural springs. In the examination, a vivid dark green colored foreign body moving towards the nasopharynx and hypopharynx was detected in the oropharynx. The leech was removed under local anesthesia by gently grasping with the help of a long clamp. It should be noted that leeches are common in rural water sources and they can cause severe morbidity and even mortalities due to serious complications such as severe anemia and airway obstructions. A thorough oral and oropharyngeal examination will be sufficient to identify such cases, indicating the importance of physical examination in patients that present with otherwise unexplained airway obstruction and hemoptysis.

Characterization of a monoacylglycerol lipase in the medicinal leech, Hirudo verbana

Endocannabinoids are a class of lipid neuromodulators found throughout the animal kingdom. Among the endocannabinoids, 2-arachydonoyl glycerol (2-AG) is the most prevalent endocannabinoid and monoacylglycerol lipase (MAGL) is a serine hydrolase primarily responsible for metabolizing 2-AG in mammals. In the medicinal leech, Hirudo verbana, 2-AG has been found to be an important and multi-functional modulator of synaptic transmission and behavior. However, very little is known about the molecular components of its synthesis and degradation. In this study we have identified cDNA in Hirudo that encodes a putative MAGL (HirMAGL). The encoded protein exhibits considerable sequence and structural conservation with mammalian forms of MAGL, especially in the catalytic triad that mediates 2-AG metabolism. Additionally, HirMAGL transcripts are detected in the Hirudo central nervous system. When expressed in HEK 293 cells HirMAGL segregates to the plasma membrane as expected. It also exhibits serine hydrolase activity that is blocked when a critical active site residue is mutated. HirMAGL also demonstrates the capacity to metabolize 2-AG and this capacity is also prevented when the active site is mutated. Finally, HirMAGL activity is inhibited by JZL184 and MJN110, specific inhibitors of mammalian MAGL. To our knowledge these findings represent the first characterization of an invertebrate form of MAGL and show that HirMAGL exhibits many of the same properties as mammalian MAGL's that are responsible for 2-AG metabolism.

Complications of leech therapy

OBJECTIVE

The principle of the use of leeches is associated with traditional medicine of many countries and its application has different philosophies for use in different areas of the body. Leeches, with all the benefits, can have dangers.

MATERIALS AND METHODS

A review of complications of leech therapy was done based on English articles indexed in the databases up to July 1, 2018. A strategic search has done independently by members of the research team and then all of the articles were +categorized by subject.

RESULTS

Related articles were mostly case-reports. Complications were divided into five categories including infection, allergy, prolonged bleeding, migration, and others. Infection is the most-reported complication related to leech therapy and Aeromonas spp. has the most participation in infections.

CONCLUSION

Leech therapy can be a therapeutic complementary method if the possible complications are managed properly.

Identification and characterization of hirudin-HN, a new thrombin inhibitor, from the salivary glands of Hirudo nipponia

Transcriptome sequencing data (6.5 Gb) of the salivary glands of the haematophagous leech Hirudo nipponia was obtained by using the BGIseq-500 platform. After identification and analysis, one transcript (Unigene5370) was annotated to hirudin HV3 from Hirudo medicinalis with an e-value of 1e-29 and was named hirudin-HN. This transcript was a new thrombin inhibitor gene belonging to the proteinase inhibitor I14 (hirudin) family. Hirudin-HN, with a 270-bp cDNA, encodes an 89-aa protein containing a 20-aa signal peptide. The mature hirudin-HN protein contains the typical structural characteristics of hirudin, e.g., three conserved disulfide bonds and the PKP and DFxxIP motifs. Proteins (Hir and M-Hir) were obtained via prokaryotic expression, and the mature hirudin-HN protein was shown to have anticoagulant activity and thrombin affinity by using the chromogenic substrate S2238 and surface plasmon resonance (SPR) interaction analysis, respectively. The N-terminal structure of the mature hirudin-HN protein was shown to be important for anticoagulant activity by comparing the activity and thrombin affinity of Hir and M-Hir. The abundances of Hirudin-HN mRNA and protein were higher in the salivary glands of starving animals than in those of feeding or fed leeches. These results provided a foundation for further study on the structure-function relationship of hirudin-HN with thrombin.

Pediatric Vaginal Leech Infestation with Severe Bleeding: A Case Report and Review Article

BACKGROUND

Vaginal leech infestation is a rare event with vaginal bleeding being its prominent sign. Few cases have been reported in young children.

CASE

In this article, we present a case of vaginal leech infestation in a 2-year-old girl who presented with significant vaginal bleeding that caused severe acute anemia, prompting transfusion. On examination, she appeared anemic, but healthy, without any signs of pubertal development. The leech was seen during examination with the patient under anesthesia and was removed. With removal of the leech, bleeding decreased significantly and stopped completely after 2 hours. She was discharged the next day in good condition.

SUMMARY AND CONCLUSION

The important concern in vaginal leech infestation is early diagnosis to prevent severe acute anemia and shock.

Leeches attenuate blood hyperviscosity and related metabolic disorders in rats differently than aspirin

ETHNOPHARMACOLOGICAL RELEVANCE

Whitmania pigra Whitman (Whitmania pigra, WP), firstly recorded in the Shennong's Herbal Classic and officially listed in the Chinese Pharmacopoeia, is a well-used cardiovascular protective traditional Chinese medicine derived from leeches. Traditional Chinese physicians prefer to prescribe the dried whole body of leech processed under high temperatures. It has been reported that dried WP remains clinically effective. However, the therapeutic mechanism has yet not be clearly elucidated.

AIM OF THE STUDY

This study was designed to investigate the protective activity of the extract of WP in a high-molecular-weight dextran-induced blood hyperviscosity rat model, and to explore the role of WP in improving blood hyperviscosity related metabolic disorders and to clarify the possible mechanism of metabolic regulation.

MATERIALS AND METHODS

The hemorheological parameters were measured with an automated blood rheology analyzer. Hematoxylin-eosin staining was used to observe the pathological changes in aortic tissues samples. Further, a liquid chromatography-mass-spectrometry (LC-MS)-based untargeted metabolomics approach was applied to characterize the metabolic alterations.

RESULTS

WP has evident attenuating effects on blood hyperviscosity and related metabolic disorders, and the influences are distinct from those of aspirin. The results showed that WP had good effects in reducing blood viscosity and ameliorating histopathological changes in the thoracic aorta in a high molecular weight dextran-induced blood hyperviscosity rat model. The middle dose (2.5 g raw material/kg body weight) of WP exhibited effects equivalent to aspirin (100 mg/kg) on hemorheological and histopathological parameters (P > 0.05). However, when using metabolomics profiling, we found that WP could significantly improve blood hyperviscosity-related metabolic disorders and restore metabolites to normal levels; while aspirin showed little effect. With principal component analysis and orthogonal partial least-squares discriminant analysis, WP regulated many more endogenous metabolites than aspirin. With pathway enrichment analysis, the differential endogenous metabolites were involved in cysteine and methionine metabolism, TCA cycle, arachidonic acid metabolism, etc., highlighting the metabolic reprogramming potential of WP against blood hyperviscosity-induced metabolic disorders.

CONCLUSIONS

The study suggest that WP has a more potent effect, but a different mechanism, than aspirin in improving either blood hyperviscosity or related metabolic disorders associated with cardio- and cerebrovascular diseases.

Behavioral analysis of substrate texture preference in a leech, Helobdella austinensis

Leeches in the wild are often found on smooth surfaces, such as vegetation, smooth rocks or human artifacts such as bottles and cans, thus exhibiting what appears to be a "substrate texture preference". Here, we have reproduced this behavior under controlled circumstances, by allowing leeches to step about freely on a range of silicon carbide substrates (sandpaper). To begin to understand the neural mechanisms underlying this texture preference behavior, we have determined relevant parameters of leech behavior both on uniform substrates of varying textures, and in a behavior choice paradigm in which the leech is confronted with a choice between rougher and smoother substrate textures at each step. We tested two non-exclusive mechanisms which could produce substrate texture preference: (1) a Differential Diffusion mechanism, in which a leech is more likely to stop moving on a smooth surface than on a rough one, and (2) a Smoothness Selection mechanism, in which a leech is more likely to attach its front sucker (prerequisite for taking a step) to a smooth surface than to a rough one. We propose that both mechanisms contribute to the texture preference exhibited by leeches.

Evaluating the ontogenetic external morphology of an ectoparasitic Torix tukubana (Hirudinida: Glossiphoniidae), with records of its new host amphibian species

Torix is a leech genus containing freshwater proboscidate species, and several members of this taxon are ectoparasites specific to amphibians. Torix tukubana inhabits mountain streams in Japan, and only two frog species are known to be hosts. We collected this leech from two other amphibians, Onychodactylus japonicus (Japanese clawed salamander) and Rana ornativentris (montane brown frog), for the first time. This finding suggests that the host specificity of T. tukubana is low. The immature individuals of T. tukubana were also collected and identified based on DNA data. This is the first juvenile record of this species confirmed by its DNA barcode sequences. Several morphological characters known from large individuals and used as diagnostic characteristics in taxonomic keys were not observed in the juveniles, suggesting that these are ontogenetic traits.

Are the persistent effects of "gate control" stimulation on nociception a form of generalization of habituation that is endocannabinoid-dependent?

Repetitive activation of non-nociceptive afferents is known to attenuate nociceptive signaling. However, the functional details of how this modulatory process operates are not understood and this has been a barrier in using such stimuli to effectively treat chronic pain. The present study tests the hypothesis that the ability of repeated non-nociceptive stimuli to reduce nociception is a form of generalized habituation from the non-nociceptive stimulus-response pathway to the nociceptive pathway. Habituation training, using non-nociceptive mechanosensory stimuli, did reduce responses to nociceptive thermal stimulation. This generalization of habituation to nociceptive stimuli required endocannabinoid-mediated neuromodulation, although disrupting of endocannabinoid signaling did not affect "direct" habituation of to the non-nociceptive stimulus. Surprisingly, the reduced response to nociceptive stimuli following habituation training was very long-lasting (3-8 days). This long-term habituation required endocannabinoid signaling during the training/acquisition phase, but endocannabinoids were not required for post-training retention phase. The implications of these results are that applying principles of habituation learning could potentially improve anti-nociceptive therapies utilizing repeated non-nociceptive stimulation such as transcutaneous nerve stimulation (TENS), spinal cord stimulation (SCS), or electro-acupuncture.

Circuit architecture for somatotopic action selection in invertebrates

Invertebrate species have significantly contributed to neuroscience owing to the accessibility they provide to cellular- and molecular-level understanding of brain functions. Somatotopic action selection is one of the key features of animal behavior, and studying this process in invertebrates is potentially a sweet spot in understanding the general relationship between neuronal morphology, circuit structure, and animal behavior. In this review, we introduce circuit architectures that realize somatotopic action selection, from simple reflexes to patterned motor outputs, in different invertebrate species. We then discuss future directions towards understanding the general principles underlying the development and evolution of the circuit architecture that enables sensorimotor transformation and action selection in the animal kingdom.

Analysis of codon usage patterns in Hirudinaria manillensis reveals a preference for GC-ending codons caused by dominant selection constraints

Background

Hirudinaria manillensis is an ephemeral, blood-sucking ectoparasite, possessing anticoagulant capacities with potential medical applications. Analysis of codon usage patterns would contribute to our understanding of the evolutionary mechanisms and genetic architecture of H. manillensis, which in turn would provide insight into the characteristics of other leeches. We analysed codon usage and related indices using 18,000 coding sequences (CDSs) retrieved from H. manillensis RNA-Seq data.

Results

We identified four highly preferred codons in H. manillensis that have G/C-endings. Points generated in an effective number of codons (ENC) plot distributed below the standard curve and the slope of a neutrality plot was less than 1. Highly expressed CDSs had lower ENC content and higher GC content than weakly expressed CDSs. Principal component analysis conducted on relative synonymous codon usage (RSCU) values divided CDSs according to GC content and divided codons according to ending bases. Moreover, by determining codon usage, we found that the majority of blood-diet related genes have undergone less adaptive evolution in H. manillensis, except for those with homologous sequences in the host species.

Conclusions

Codon usage in H. manillensis had an overall preference toward C-endings and indicated that codon usage patterns are mediated by differential expression, GC content, and biological function. Although mutation pressure effects were also notable, the majority of genetic evolution in H. manillensis was driven by natural selection.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4937-x) contains supplementary material, which is available to authorized users.

Extensive depolarization and lack of recovery of leech Retzius neurons caused by 2,4 diaminobutyric acid

In this paper we present, for the first time, a detailed account of electrophysiological effects of 2,4-diaminobutyric acid (2,4-DABA). 2,4-DABA is a neurotoxic non-protein amino acid produced by Cyanobacteria with a possible link to neurodegenerative disorders in animals and humans. Intracellular recordings were performed on Retzius nerve cells of the leech Haemopis sanguisuga using glass microelectrodes filled with 3 mol/L KCl. Our results show that 2,4-DABA is an excitatory amino acid, causing membrane depolarization in a concentration-dependent manner. The most prominent depolarizations of 39.63±2.22 mV and 47.05±4.33 mV, induced by 5×10^-3 and 10^-2 mol/L 2,4-DABA respectively, are several times larger than maximal depolarizations induced by either Glutamate, Aspartate, β-N-methylamino-alanine (BMAA) or β-N-oxalylamino-alanine (BOAA) on our model. These 2,4-DABA induced depolarizations evolve through two distinct stages, which is a novel phenomenon in electrical cell activity upon application of an excitatory amino acid, at least on our model. Involvement of two separate mechanisms, suggested by the two stage phenomenon, is discussed in the paper. We also provide evidence that 2,4-DABA induces irreversible functional disturbances in neurons in a concentration-dependent manner, since only half of the cells recovered normal electrical activity after application of 5×10^-3 mol/L 2,4-DABA, and none recovered after application of 10^-2 mol/L 2,4-DABA. Effects of both L-2,4-DABA and DL-2,4-DABA were tested and are not significantly different.

Batracobdella leeches, environmental features and Hydromantes salamanders

Leeches can parasitize many vertebrate taxa. In amphibians, leech parasitism often has potential detrimental effects including population decline. Most of studies on the host-parasite interactions involving leeches and amphibians focus on freshwater environments, while they are very scarce for terrestrial amphibians. In this work, we studied the relationship between the leech Batracobdella algira and the European terrestrial salamanders of the genus Hydromantes, identifying environmental features related to the presence of the leeches and their possible effects on the hosts. We performed observation throughout Sardinia (Italy), covering the distribution area of all Hydromantes species endemic to this island. From September 2015 to May 2017, we conducted >150 surveys in 26 underground environments, collecting data on 2629 salamanders and 131 leeches. Water hardness was the only environmental feature correlated with the presence of B. algira, linking this leech to active karstic systems. Leeches were more frequently parasitizing salamanders with large body size. Body Condition Index was not significantly different between parasitized and non-parasitized salamanders. Our study shows the importance of abiotic environmental features for host-parasite interactions, and poses new questions on complex interspecific interactions between this ectoparasite and amphibians.

•

Sardinian Hydromantes salamanders are often parasitized by Batracobdella algira.

•

Underground presence of B. algira is strongly associated to active karstic systems.

•

Leeches often parasitize large-sized salamanders.

•

Parasitism of B. algira does not affect Body Condition Index of salamanders.

Pediatric Vulvar Bleeding due to Leech Infestation: A Case Report

Leech infestation most frequently occurs in upper body cavities of children including pharynx, nose and esophagus and, more rarely, the vagina and vulva. Here we describe a 6-yr-old girl with vulvar bleeding caused by leech infestation that referred to the Emergency unit of the Booali Sina Hospital in Sari, Iran in Sep 2015. She had a history of swimming in a pond prior to the occurrence. The leech infestation particularly vulvar involvement among young girls is extremely rare and yet neglected event in the world.

Developmental biology and potential use of Alboglossiphonia lata (Annelida: Hirudinea) as an "Evo-Devo" model organism

BACKGROUND

The need for the adaptation of species of annelids as "Evo-Devo" model organisms of the superphylum Lophotrochozoa to refine the understanding of the phylogenetic relationships between bilaterian organisms, has promoted an increase in the studies dealing with embryonic development among related species such as leeches from the Glossiphoniidae family. The present study aims to describe the embryogenesis of Alboglossiphonia lata (Oka, 1910), a freshwater glossiphoniid leech, chiefly distributed in East Asia, and validate standard molecular biology techniques to support the use of this species as an additional model for "Evo-Devo" studies.

RESULTS

A. lata undergoes direct development, and follows the highly conserved clitellate annelid mode of spiral cleavage development; the duration from the egg laying to the juvenile stage is ~7.5 days, and it is iteroparous, indicating that it feeds and deposits eggs again after the first round of brooding, as described in several other glossiphoniid leech species studied to date. The embryos hatch only after complete organ development and proboscis retraction, which has not yet been observed in other glossiphoniid genera. The phylogenetic position of A. lata within the Glossiphoniidae family has been confirmed using cytochrome c oxidase subunit 1 (CO1) sequencing. Lineage tracer injections confirmed the fates of the presumptive meso- and ectodermal precursors, and immunostaining showed the formation of the ventral nerve system during later stages of development. Further, the spatiotemporal expression of an EF-hand calcium-binding protein Calsensin ortholog was characterized, which showed a specific pattern in both the ventral and peripheral nervous systems during the later stages.

CONCLUSIONS

Our description of the embryonic development of A. lata under laboratory conditions provides new data for further comparative studies with other leech and lophotrochozoa model organisms. Moreover, it offers a basis for the establishment of this species as a model for future "Evo-Devo" studies.

Severe anemia due to pharyngeal leech infestation; a case report from Ethiopia

Background

Leeches are rare blood-sucking endoparasites. Swimming in streams and ponds as well as drinking contaminated water are the major ways to acquire leeches.

Case presentation

A 6 year old boy who came with a history of hematemesis, frequent spitting of blood stained saliva, fatigue and anorexia to a rural hospital in Ethiopia. This was a rare case of severe anemia caused by a single leech infestation of laryngopharynx that required blood transfusion.

Conclusion

Leech infestation should be considered as a source of unexplained hematemesis, spitting of blood and severe anemia in rural areas.

Spatiotemporal expression of a twist homolog in the leech Helobdella austinensis

Genes of the twist family encode bHLH transcription factors known to be involved in the regulation and differentiation of early mesoderm. Here, we report our characterization of Hau-twist, a twist homolog from the leech Helobdella austinensis, a tractable lophotrochozoan representative. Hau-twist was expressed in segmental founder cells of the mesodermal lineage, in subsets of cells within the mesodermal lineage of the germinal plate, in circumferential muscle fibers of a provisional integument during segmentation and organogenesis stages and on the ventral side of the developing proboscis. Thus, consistent with other systems, our results suggest that twist gene of the leech Helobdella might function in mesoderm differentiation.

[A rare case report of laryngeal leech infestation in a 70-year-old man]

La dyspnée laryngée représente une urgence extrême en otorhinolaryngologies. Elle répond à des étiologies multiples et reste souvent graves. La dyspnée laryngée causée par une sangsue est exceptionnellement décrite dans la littérature surtout chez l’adulte. Nous rapportons une observation particulière d’infestation de l’arbre respiratoire par une sangsue ayant entraîné une dyspnée laryngée.

Helobdella blinni sp. n. (Hirudinida, Glossiphoniidae) a new species inhabiting Montezuma Well, Arizona, USA

A new leech species Helobdellablinnisp. n., is described from Montezuma Well, an isolated travertine spring mound located in central Arizona, USA. In its native habitat, Helobdellablinni had been previously identified as Helobdellastagnalis (Linnaeus, 1758), which was later reclassified to Helobdellamodesta (Verrill, 1872). Similar to the European Helobdellastagnalis and North American Helobdellamodesta, Helobdellablinni has six pairs of testisacs, five pairs of smooth crop caecae, one lobed pair of posteriorly-directed crop caecae, one pair of eyes, a nuchal scute, and diffuse salivary glands. However, the pigmentation of this new species ranges from light to dark brown, unlike Helobdellamodesta which tends to be light grey in color. Also, Helobdellamodesta produces a clutch of 12-–35 pink eggs, whereas Helobdellablinni produces smaller clutches of white eggs (7–14, 0.5 ± 0.15 mm, N = 7) and consequently broods fewer young (1–14, 7 ± 3.3 mm, N = 97). Helobdellablinni are also able to breed year-round due to the constant warm water conditions in Montezuma Well. Their breeding season is not restricted by seasonal temperatures. These species are morphologically similar, however, comparing the COI mtDNA sequences of Helobdellablinni with sequences from nearby populations of Helobdellamodesta and other Helobdella species from GenBank indicate that Helobdellablinni is genetically distinct from these other Helobdella populations.

Identification and characterization of a novel neuropeptide (neuropeptide Y-HS) from leech salivary gland of Haemadipsa sylvestris

The present study was designed to identify immunomodulatory components from the leech salivary gland of Haemadipsa sylvestris. The Sephadex G-50, Resource(TM) S column chromatography and reverse-phase high performance liquid chromatography (RP-HPLC) were used to isolate and purify the salivary gland extracts (SGE). Structural analysis of isolated compounds was based on Edman degradation and matrix assisted laser desorption ionization time-of-flight mass spectrometer (MALDI-TOF-MS). The cDNA encoding the precursor of the compound was cloned from the cDNA library of the salivary gland of H. sylvestris. The levels of inflammatory mediators, including tumor necrosis factor-α (TNF-α), interferon γ (IFN-γ), interleukin-6 (IL-6), and monocyte chemotactic protein-1 (MCP-1) were assayed using an enzyme-linked immunosorbent assay (ELISA). The effects on cell proliferation and cell viability were observed using MTT assay. A novel neuropeptide Y (Neuropeptide Y-HS) from the leech salivary gland of H. sylvestris was purified and characterized. It was composed of 36 amino acid residues and the amino acid sequence was determined to be FLEPPERPAVFTSVEQMKSYIKALNDYYLLLGRPRF-NH2, containing an amidated C-terminus. It showed significant inhibitory effects on the production of inflammatory cytokines including TNF-α, IFN-γ, IL-6, and MCP-1. Neuropeptide Y was identified from leeches for the first time. The presence of neuropeptide Y-HS in leech salivary gland may help get blood meal from hosts and inhibit inflammation.