Venom characterization of the Amazonian scorpion Tityus metuendus

The complex repertoire of Tityus spp. venoms: Advances on their composition and pharmacological potential of their toxins

Animal venoms are a rich and complex source of components, including peptides (such as neurotoxins, anionic peptides and hypotensins), lipids, proteins (such as proteases, hyaluronidases and phospholipases) and inorganic compounds, which affect all biological systems of the envenoming victim. Their action may result in a wide range of clinical manifestations, including tachy/bradycardia, hyper/hypotension, disorders in blood coagulation, pain, edema, inflammation, fever, muscle paralysis, coma and even death. Scorpions are one of the most studied venomous animals in the world and interesting bioactive molecules have been isolated and identified from their venoms over the years. Tityus spp. are among the scorpions with high number of accidents reported in the Americas, especially in Brazil. Their venoms have demonstrated interesting results in the search for novel agents with antimicrobial, anti-viral, anti-parasitic, hypotensive, immunomodulation, anti-insect, antitumor and/or antinociceptive activities. Furthermore, other recent activities still under investigation include drug delivery action, design of anti-epileptic drugs, investigation of sodium channel function, treatment of erectile disfunction and priapism, improvement of scorpion antivenom and chelating molecules activity. In this scenario, this paper focuses on reviewing advances on Tityus venom components mainly through the modern omics technologies as well as addressing potential therapeutic agents from their venoms and highlighting this abundant source of pharmacologically active molecules with biotechnological application.

Exploring the potential of Brazilian Amazonian scorpion venoms: A comprehensive review of research from 2001 to 2021

The Amazon biome is home to many scorpion species, with around two hundred identified in the region. Of these, forty-eight species have been reported in Brazil so far and six of them are of medical importance: Tityus apiacas, T. metuendus, T. obscurus, T. raquelae, T. silvestris, and T. strandi. Three non-medically important species have also been studied: Opisthanthuscayaporum, Brotheas amazonicus and Rhopalurus laticauda. The venom of the scorpion T. obscurus is the most studied, followed by O. cayaporum. We aim to update the study of these Amazonian scorpion species. We will explore the harmful and beneficial properties of scorpion venom toxins and how they could be applied in drug development. This systematic review will focus on collecting and analyzing venoms from scorpions in Brazil. Only papers on Amazonian scorpion venom studies published between 2001 and 2021 (scientific articles, theses, and dissertations) were selected, based on the lists of scorpions available in the literature. Species found in the Amazon but not confirmed to be Brazilian were omitted from the review. Theses and dissertations were chosen over their derived articles. We found 42 eligible studies (13 theses, 27 articles and 2 patents) out of 17,950 studies and a basic statistical analysis was performed. The literature showed that T. obscurus was the most studied venom with 28 publications, followed by O. cayaporum with seven articles, B. amazonicus with four articles, T. metuendus with two article and R. laticauda with one article. No publication on the characterization of T. silvestris and T. apiacas venoms were found during the reviewed period, only the clinical aspects were covered. There is still much to be explored despite the increasing number of studies conducted in recent years. Amazonian scorpions have promising potential for pharmaceutical and clinical applications.

Leishmanicidal activity of the venoms of the Scorpions Brotheas amazonicus and Tityus metuendus

Leishmaniasis is a vector-transmitted zoonosis caused by different species of the genus Leishmania, with a wide clinical spectrum. It is a public health problem aggravated by a series of limitations regarding treatment. In the search for new therapeutic alternatives, scorpion venoms are a source of multifunctional molecules that act against the natural resistance of pathogens. This work evaluated the antileishmanial potential of Brotheas amazonicus and Tityus metuendus venoms against the promastigote forms of Leishmania amazonensis e Leishmania guyanensis. The venoms of B. amazonicus and T. metuendus were evaluated for their constituents using Fourier Transform Infrared (FTIR). Growth inhibition and death of promastigotes were evaluated in the presence of diferente crude venom concentrations (100 µg/mL, 50 µg/mL, 10 µg/mL, 1 µg/mL) after one hour of incubation at 25 °C. The FTIR spectra of both venoms exhibited bands in approximate regions, revealing that both exhibit similar functional groups. Crude venom from both scorpion species showed similar or superior leishmanicidal effects to the standart drug N-methylglucamine antimoniate. At the highest concentration of 100 µg/mL, cultures of L. guyanensis treated with the venom of B. amazonicus showed the highest mortality percentages, above 28%, while T. metuendus venom showed the highest activity against L. amazonensis, with mortality above 7%. This preliminar study demonstrates that B. amazonicus and T. metuendus venoms can be important tools in the search for new drugs Against leishmaniasis. Next step involves evaluating the activity against the amastigote forms and purifying the venom proteins in order to identify the best anti-leishmania candidates.

Pioneering in vitro characterization of macrophage response induced by scorpion venoms from the Brazilian Amazon

There are several scorpion species of medical relevance around the world. Some of them are well characterized by their toxins and clinical outcomes. Brazilian Amazon has a great amount of these arthropods that have an impact in the scorpionism events specifically in this region of Brazil. Recently, several studies pointed out the immune system activation during scorpion envenouming as an important facet of scorpionism, inducing a sepsis-like state that culminates in clinical severity and death. In this work, we characterized the macrophage response of three species of clinical relevance in Brazilian Amazon: Tityus silvestris, T. metuendus and T. obscurus and one specie with no toxic effects to humans, Brotheas amazonicus. All the four species analyzed were able to induce pro- and anti-inflammatory cytokine production in a J774.1 murine macrophage model. This activation was dependent on TLR2/TLR4/MyD88 activation and abolished by TLRs antagonists. These results suggest that the venoms of the four species analyzed were able to induce macrophage response in agreement to the well-established immune activation by T. serrulatus venom. Our findings provide new insights into the clinical repercussions of scorpionism of uncharacterized species and point to new biotechnological applications of these venoms and possible supportive therapies in scorpionism.

Comparative Proteomic Analysis of the Venoms from the Most Dangerous Scorpions in Morocco: Androctonus mauritanicus and Buthus occitanus

Morocco is known to harbor two of the world's most dangerous scorpion species: the black Androctonus mauritanicus (Am) and the yellow Buthus occitanus (Bo), responsible for 83% and 14% of severe envenomation cases, respectively. Scorpion venom is a mixture of biological molecules of variable structures and activities, most of which are proteins of low molecular weights referred to as toxins. In addition to toxins, scorpion venoms also contain biogenic amines, polyamines, and enzymes. With the aim of investigating the composition of the Am and Bo venoms, we conducted an analysis of the venoms by mass spectrometry (ESI-MS) after separation by reversed-phase HPLC chromatography. Results from a total of 19 fractions obtained for the Am venom versus 22 fractions for the Bo venom allowed the identification of approximately 410 and 252 molecular masses, respectively. In both venoms, the most abundant toxins were found to range between 2-5 kDa and 6-8 kDa. This proteomic analysis not only allowed the drawing of an extensive mass fingerprint of the Androctonus mauritanicus and Buthus occitanus venoms but also provided a better insight into the nature of their toxins.

On the noxious black Amazonian scorpion, Tityus obscurus (Scorpiones, Buthidae): Taxonomic notes, biology, medical importance and envenoming treatment

Tityus obscurus has caused mild, moderate and severe accidents of medical relevance in the eastern Brazilian Amazon and French Guiana. Tityus obscurus has sexual dimorphism although males and females have uniform black coloration. In the Amazon, one of the habitats of this scorpion is seasonally flooded forests (igapós and várzeas). However, most stings occur in terra firme forest areas (non-flooded region), where most rural communities are located. Adults and children stung by T. obscurus may experience an "electric shock" sensation for more than 30 h after the sting. Our data shows that people inhabiting remote forest areas, including rubber tappers, fishermen and indigenous people, with no access to anti-scorpion serum, use parts of native plants, such as seeds and leaves, against pain and vomiting caused by scorpion stings. Although there is a technical effort to produce and distribute antivenoms in the Amazon, many cases of scorpion stings are geographically unpredictable in this region, due to the lack of detailed knowledge of the natural distribution of these animals. In this manuscript, we compile information on the natural history of T. obscurus and the impact of its envenoming on human health. We identify the natural sites that host this scorpion in the Amazon, in order to warn about the risk of human envenoming. The use of specific antivenom serum is the recommended treatment for accidents involving venomous animals. However, atypical symptoms not neutralized by the available commercial antivenom are reported in the Amazon region. Facing this scenario, we present some challenges to the study of venomous animals in the Amazon rainforest and possible experimental bottlenecks and perspectives for establishing a method aimed at producing an efficient antivenom.

The remarkably enzyme-rich venom of the Big Bend Scorpion (Diplocentrus whitei)

Scorpion venoms have long been studied for their peptide discovery potential, with modern high-throughput venom-characterization techniques paving the way for the discovery of thousands of novel putative toxins. Research into these toxins has provided insight into the pathology and treatment of human diseases, even resulting in the development of one compound with Food and Drug Administration (FDA) approval. Although most of this research has focused on the toxins of scorpion species considered medically significant to humans, the venom of harmless scorpion species possess toxins that are homologous to those from medically significant species, indicating that harmless scorpion venoms may also serve as valuable sources of novel peptide variants. Furthermore, as harmless scorpions represent a vast majority of scorpion species diversity, and therefore venom toxin diversity, venoms from these species likely contain entirely new toxin classes. We sequenced the venom-gland transcriptome and venom proteome of two male Big Bend scorpions (Diplocentrus whitei), providing the first high-throughput venom characterization for a member of this genus. We identified a total of 82 toxins in the venom of D. whitei, 25 of which were identified in both the transcriptome and proteome, and 57 of which were only identified in the transcriptome. Furthermore, we identified a unique, enzyme-rich venom dominated by serine proteases and the first arylsulfatase B toxins identified in scorpions.

An overview of Tityus cisandinus scorpion venom: Transcriptome and mass fingerprinting reveal conserved toxin homologs across the Amazon region and novel lipolytic components

Tityus cisandinus, a neglected medically important scorpion in Ecuadorian and Peruvian Amazonia, belongs to a complex of species related to the eastern Amazon endemic Tityus obscurus, spanning a distribution of ca. 4000 km. Despite high morbidity and mortality rates, no effective scorpion antivenom is currently available in the Amazon region. Knowledge of the structural/functional relationships between T. cisandinus venom components and those from related Amazonian species is crucial for designing region-specific therapeutic antivenoms. In this work, we carried out the first venom gland transcriptomic study of an Amazonian scorpion outside Brazil, T. cisandinus. We also fingerprinted its total venom through MALDI-TOF MS, which supported our transcriptomic findings. We identified and calculated the expression level of 94 components: 60 toxins, 25 metalloproteases, five disulfide isomerases, three amidating enzymes, one hyaluronidase, and also uncovered transcripts encoding novel lipolytic beta subunits produced by New World buthid scorpions. This study demonstrates the high similarity between T. cisandinus and T. obscurus venoms, reinforcing the existence of a neglected complex of genetically and toxinologically related Amazonian scorpions of medical importance. Finally, we demonstrated the low recognition of currently available therapeutic sera against T. cisandinus and T. obscurus venoms, and concluded that these should be improved to protect against envenomation by Amazonian Tityus spp.

French Scorpionism (Mainland and Oversea Territories): Narrative Review of Scorpion Species, Scorpion Venom, and Envenoming Management

Sixty-seven scorpion species have been described in France and its territories, where they have been found to be heterogeneously distributed. Indeed, only one species can be found on Réunion Island, while 38 species exist in French Guiana. The number of stings is also heterogenous, with up to 90 stings per 100,000 inhabitants occurring annually. Scorpion species can frequently be determined through simple visual factors, including species of medical importance (i.e., Buthus, Centruroides and Tityus). Scorpion venom is composed of local enzymes and peptides with a cysteine-stabilized α/β motif (NaTxs, Ktxs, Calcines), which allow for venom diffusion and the prey's incapacitation, respectively. Harmful scorpion species are limited to Centruroides pococki in the French West Indies, which can induce severe envenoming, and the Tityus obscurus and Tityus silvestris in French Guiana, which can cause fatalities in children and can induce severe envenoming, respectively. Envenomation by one of these scorpions requires hospital monitoring as long as systemic symptoms persist. Typical management includes the use of a lidocaine patch, pain killers, and local antiseptic. In the case of heart failure, the use of dobutamine can improve survival, and pregnant women must consult an obstetrician because of the elevated risk of preterm birth or stillbirth. France does not have scorpion antivenom, as scorpion stings are generally not fatal.

Amazonian scorpions and scorpionism: integrating toxinological, clinical, and phylogenetic data to combat a human health crisis in the world's most diverse rainfores

Venom from Amazonian scorpions of the genus Tityus contains components capable of eliciting a distinct clinical, mostly neurological, syndrome. This contrasts with the mainly autonomic manifestations produced after envenomation by congeneric southern and northern South American species. Herein, we summarize Pan-Amazonian scorpionism by synthesizing available toxinological, clinical, and molecular data gathered from all affected areas in Amazonia, including Brazil, Ecuador, Colombia, Peru, Venezuela, and French Guiana. We searched multiple databases, as well as our own records, for reports of scorpion envenomations in Amazonia by confirmed Tityus spp., and compared the clinical manifestations. To help uncover clinical and venom relationships among problematic species, we explored phylogenetic relationships with a rate-calibrated analysis of mitochondrial COI data from available species. The possible existence of diversity gradients for venom toxic and immunogenic components despite the predicted strong phylogenetic association among species is underscored by discussed clinical and toxinological findings. A multicentric effort, involving all nations affected by this neglected disease, is urgently needed to offer alternatives for treating and understanding this pathology, including the preparation of neutralizing antibodies with a broad range of efficacy.

Scorpion species of medical importance in the Brazilian Amazon: a review to identify knowledge gaps

Scorpionism is a relevant medical condition in Brazil. It is responsible for most accidents involving venomous animals in the country, which leads to severe symptoms that can evolve to death. In recent years, an increase of almost 50% in the incidence of scorpionism has been observed in the Northern Region, where the highest severity of envenoming has been notified since the beginning of the 21st century. This review aims to provide an in-depth assessment of public data and reports on symptoms and epidemiology of envenoming, ecological aspects of scorpions, and characterization of venoms and toxins to access the gaps that need to be filled in the knowledge of the scorpion species of medical importance from the Brazilian Amazon. A systematic search using the string words "Amazon" and "scorpion" was performed on 11 databases. No restriction on date, language or status of the publication was applied. Reports not related to the Brazilian Amazon were excluded. Therefore, 88 studies remained. It is shown that populations of scorpions of medical importance, even of the same species, may present significant toxic variations peculiar to some regions in the Brazilian Amazon, and commercial scorpion antivenoms were not able to shorten the intensity and duration of neurological manifestations in patients stung by T. silvestris, T. apiacas or T. obscurus. It is also highlighted that the toxins responsible for triggering these alterations have not been elucidated yet and this is a fruitful field for the development of more efficient antivenoms. Furthermore, the geographic distribution of scorpions of the genus Tityus in the Brazilian Amazon was revised and updated. The cumulative and detailed information provided in this review may help physicians and scientists interested in scorpionism in the Brazilian Amazon.

Exploring the biological activities and proteome of Brazilian scorpion Rhopalurus agamemnon venom

Scorpion venoms are formed by toxins harmful to various organisms, including humans. Several techniques have been developed to understand the role of proteins in animal venoms, including proteomics approach. Rhopalurus agamemnon (Koch, 1839) is the largest scorpion in the Buthidae family in the Brazilian Cerrado, measuring up to 110 mm in total length. The accident with R. agamemnon is painful and causes some systemic reactions, but the specie's venom remains uninvestigated. We explore the venom protein composition using a proteomic and a biological-directed approach identifying 230 protein compounds including enzymes like Hyaluronidase, metalloproteinase, L-amino acid oxidase and amylase, the last two are first reported for scorpion venoms. Some of those new reports are important to demonstrate how distant we are from a total comprehension of the diversity about venoms in general, due to their diversity in composition and function. BIOLOGICAL SIGNIFICANCE: In this study, we explored the composition of venom proteins from the scorpion Rhopalurus agamemnon. We identified 230 proteins from the venom including new enzyme reports. These data highlight the unique diversity of the venom proteins from the scorpion R. agamemnon, provide insights into new mechanisms of envenomation and enlarge the protein database of scorpion venoms. The discovery of new proteins provides a new scenario for the development of new drugs and suggests molecular targets to venom components.

Clinical profile of confirmed scorpion stings in a referral center in Manaus, Western Brazilian Amazon

Scorpion envenomations are a major public health problem in Brazil, and most medically important cases are attributable to the Tityus genus. The objective of this study is to describe the clinical and epidemiological aspects of a series of 151 cases of confirmed scorpion stings, which were treated at the hospitals of two cities in the Western Brazilian Amazon, between June 2014 and December 2019. This study shows that the genus Tityus was the most prevalent. Tityus (Atreus) metuendus (Pocock, 1897) was responsible for the greatest number of cases (68.2%), followed by Tityus (Archaeotityus) silvestris (Pocock, 1897) (14.6%). Most of the envenomations involved males (53.6%), and analysis showed a slight predominance in the group from 40 to 49 years (22.5%). The most affected body regions were feet (49.0%) and hands (31.8%). The time elapsed between the accident and medical care was ≤6 h in 92.1% of cases. Regarding clinical severity, classes I (80.8%) and II (15.9%) predominated. However, there were five (3.3%) class III cases; four for T. metuendus and one for T. silvestris. The most frequent local and systemic manifestations were, respectively, pain (84.1%), paresthesia (34.4%) and mild edema (25.8%), and nausea (9.3%) and myoclonia (8.6%). The clinical manifestations were similar among the patients stung by the different species of scorpions. There were no differences between the manifestations of envenomation caused by T. metuendus, T. silvestris and T. raquelae. For victims of T. apiacas, a higher frequency of piloerection and myoclonia was observed, and was described by the affected patients as a 'sensation of receiving an electric shock' throughout the body. No deaths were registered. The species of greatest epidemiological importance in Manaus is T. metuendus, a species that leads to clinical pictures that do not differ substantially from those observed in other Brazilian regions. T. apiacas causes neurological manifestations that differed from other Tityus species. Our findings suggest that the available antivenoms have little effectiveness when used in the treatment of envenomations by some Amazonian scorpions.

Venom diversity in the Neotropical scorpion genus Tityus: Implications for antivenom design emerging from molecular and immunochemical analyses across endemic areas of scorpionism

Scorpions of the Neotropical genus Tityus are responsible for most severe envenomations in the Caribbean, South America, and Lower Central America (LCA). Although Tityus is taxonomically complex, contains high toxin polymorphism, and produces variable clinical manifestations, treatment is limited to antivenoms produced against species with restricted distributions. In this study, we explored the compositional and antigenic diversity of Tityus venoms to provide improved guidelines for the use of available antivenoms at a broader geographic scale. We used immunoblotting, competitive ELISA, and in vivo studies to compare reactivity against commercial antivenoms from Brazil, Venezuela, and Mexico, as well as MALDI-TOF mass spectrometry, cDNA sequencing, and phylogenetic analyses to assess venom sodium channel-active toxin (NaTx) content from medically important Tityus populations inhabiting Brazil, Colombia, Costa Rica, Ecuador, Panama, Trinidad and Tobago, and Venezuela. Additionally, we raised rabbit antibodies against Tityus venoms from LCA to test for cross-reactivity with congeneric species. The results suggest that Tityus spp. possess high venom antigenic diversity, underlying the existence of four toxinological regions in Tropical America, based on venom composition and immunochemical criteria: LCA/Colombia/Amazonia (Region I), Venezuela (Region II), southeast South America (Region III), and a fourth region encompassing species related to toxinologically divergent Tityus cerroazul. Importantly, our molecular and cross-reactivity results highlight the need for new antivenoms against species inhabiting Region I, where scorpions may produce venoms that are not significantly reactive against available antivenoms.

Transcriptomic and proteomic analyses of the venom and venom glands of Centruroides hirsutipalpus, a dangerous scorpion from Mexico

Centruroides hirsutipalpus (Scorpiones: Buthidae) is related to the "striped scorpion" group inhabiting the western Pacific region of Mexico. Human accidents caused by this species are medically important due to the great number of people stung and the severity of the resulting intoxication. This communication reports an extensive venom characterization using high-throughput proteomic and Illumina transcriptomic sequencing performed with RNA purified from its venom glands. 2,553,529 reads were assembled into 44,579 transcripts. From these transcripts, 23,880 were successfully annoted using Trinotate. Using specialized databases and by performing bioinformatic searches, it was possible to identify 147 putative venom protein transcripts. These include α- and β-type sodium channel toxins (NaScTx), potassium channel toxins (KScTx) (α-, β-, δ-, γ- and λ-types), enzymes (metalloproteases, hyaluronidases, phospholipases, serine proteases, and monooxygenases), protease inhibitors, host defense peptides (HDPs) such as defensins, non-disulfide bridge peptides (NDBPs), anionic peptides, superfamily CAP proteins, insulin growth factor-binding proteins (IGFBPs), orphan peptides, and other venom components (La1 peptides). De novo tandem mass spectrometric sequencing of digested venom identificatied 50 peptides. The venom of C. hirsutipalpus contains the highest reported number (77) of transcripts encoding NaScTxs, which are the components responsible for human fatalities.

Structural and functional characterization of toxic peptides purified from the venom of the Colombian scorpion Tityus macrochirus

The soluble venom of the scorpion Tityus macrochirus was separated by chromatographic procedures and three homogeneous peptides were obtained and their primary structures were determined. They were called: Tma1-Tma3, from the abbreviated name of the scorpion. Tma1 is a peptide containing 65 amino acids with four disulfide linkages and a molecular weight of 7386.2 Da. It is a mammalian toxin, shown to affect human sodium-channels sub-types hNav1.6 and hNav1.4. Tma2 and Tma3 are peptides containing 69 amino acids linked by four disulfide bonds, molecular weights 7819.7 and 7830.0 Da, respectively. They do not affect human sodium-channels but are lethal to insects (crickets). A phylogenic analysis of the three peptides and those of other toxic peptides isolated from the genus Tityus and Centruroides were grouped together and analyzed, permitting to obtain a topology with two main clades, one includes most sodium-channel anti-insect scorpion toxins and others includes mostly sodium-channel scorpion toxins anti-mammalian. Tma1 segregates among a group of well-studied β-class toxins of other Tityus species such as T. discrepans, T. obscurus and T. pachyurus. Tma2 and Tma3 are associated with anti-insect toxins, particularly with one of T. obscurus. This phylogenetic analysis confirms and enforces our experimental results obtained with these three new sodium-channel scorpion toxins.