Protective effects of batimastat against hemorrhagic injuries in delayed jellyfish envenomation syndrome models

Toxin metalloproteinases exert a dominant influence on pro-inflammatory response and anti-inflammatory regulation in jellyfish sting dermatitis

Toxin metalloproteinases are the primary components responsible for various toxicities in jellyfish venom, and there is still no effective specific therapy for jellyfish stings. The comprehension of the pathogenic mechanisms underlying toxin metalloproteinases necessitates further refinement. In this study, we conducted a differential analysis of a dermatitis mouse model induced by jellyfish Nemopilema nomurai venom (NnNV) samples with varying levels of metalloproteinase activity. Through skin tissue proteomics and serum metabolomics, the predominant influence of toxin metalloproteinase activity on inflammatory response was revealed, and the signal pathway involved in its regulation was identified. In skin tissues, many membrane proteins were significantly down-regulated, which might cause tissue damage. The expression of pro-inflammatory factors was mainly regulated by PI3K-Akt signaling pathway. In serum, many fatty acid metabolites were significantly down-regulated, which might be the anti-inflammation feedback regulated by NF-κB p65 signaling pathway. These results reveal the dermatitis mechanism of toxin metalloproteinases and provide new therapeutic targets for further studies. SIGNIFICANCE: Omics is an important method to analyze the pathological mechanism and discover the key markers, which can reveal the pathological characteristics of jellyfish stings. Our research first analyzed the impact of toxin metalloproteinases on jellyfish sting dermatitis by skin proteomics and serum metabolomics. The present results suggest that inhibition of toxin metalloproteinases may be an effective treatment strategy, and provide new references for further jellyfish sting studies.

Discovery of a novel jellyfish venom metalloproteinase inhibitor from secondary metabolites isolated from jellyfish-derived fungus Aspergillus versicolor SmT07

The major jellyfish stings that occur in China are caused by scyphozoan Nemopilema nomurai, whose venom exhibits significant metalloproteinase activity that contributes to the toxic effects of jellyfish envenomation. Researching effective inhibitors suppressing the metalloproteinase activity of jellyfish venom represents a new attempt to cure jellyfish envenomations. In the present study, secondary metabolites produced by the jellyfish-associated fungus Aspergillus versicolor SmT07 were isolated and evaluated for their anti-proteolytic activities. Two xanthones, sterigmatocystin (JC-01) and oxisterigmatocystin C (JC-06), and four alkaloids, cottoquinazoline A (JC-02), phenazine-1-carboxylic acid (JC-03), viridicatin (JC-04) and viridicatol (JC-05), were isolated and identified. Only phenazine-1-carboxylic acid (PCA) showed significant anti-proteolytic activity of jellyfish venom assayed on azocasein, and the IC₅₀ value was 2.16 mM. PCA also significantly inhibited fibrinogenolytic activity, protecting the Bβ chain of fibrinogen from degradation when preincubated with jellyfish venom at a ratio of >1:0.6 (PCA:venom, w/w). Molecular docking with several well-characterized snake venom metalloproteinases suggested the venom metalloproteinases inhibitory property of PCA by forming complex interactions with the active site via hydrogen bonds, π-π stacking and salt bridges, which was distinct from the binding mode of batimastat. The present study represents the first study identifying natural jellyfish venom metalloproteinase inhibitors from marine natural products, which may provide an alternative to develop therapeutic agents for treating jellyfish envenomations.

Jellyfish Nemopilema nomurai causes myotoxicity through the metalloprotease component of venom

Jellyfish envenomation is a common medical problem in many countries. However, the myotoxicity and effector molecules of scyphozoan venoms remain uninvestigated. Here, we present the myotoxicity of nematocyst venom from Nemopilema nomurai (NnNV), a giant venomous scyphozoan from China, for the first time, using in vivo models with inhibitors. NnNV was able to induce remarkable myotoxicity including significant muscle swelling, increasing the content of CK and LDH in serum, stimulating inflammation of muscle tissue, and destroying the structure of muscle tissue. In addition, the metalloproteinase inhibitors BMT and EDTA significantly reduced the myotoxicity induced by NnNV. Moreover, BMT and EDTA could decrease the inflammatory stimulation and necrosis of muscle tissue caused by the venom. These observations suggest that the metalloproteinase components of NnNV make a considerable contribution to myotoxicity. This study contributes to understanding the effector molecules of muscle injury caused by jellyfish stings and suggests a new idea for the treatment of scyphozoan envenomation.

Inhibitory Effect of Metalloproteinase Inhibitors on Skin Cell Inflammation Induced by Jellyfish Nemopilema nomurai Nematocyst Venom

Jellyfish envenomations result in extensive dermatological symptoms, clinically named as jellyfish dermatitis, which can seriously affect the daily activities and physical health of people. Inflammatory response accompanies the whole process of jellyfish dermatitis and the complexity of jellyfish venom components makes it difficult to treat jellyfish dermatitis symptoms effectively. Moreover, inhibiting inflammation is essential for the treatment of jellyfish stings and exploring the main components of jellyfish venom that cause inflammation is an urgent research area. In this study, the inhibitory effects of matrix metalloproteinase (MMP) inhibitors for venom-induced inflammation were explored at a cellular level. The expression of the three inflammatory factors, IL-6, TNF-α and MCP-1 in two skin cell lines, human keratinocyte cells (HaCaT) and human embryonic skin fibroblasts cells (CCC-ESF-1), at the cellular level, after treatment with the inhibitors of jellyfish Nemopilema nomurai (N. nomurai) nematocyst venom (NnNV-I), were determined. The results showed that inhibitors of MMP can significantly reduce the toxic effects of jellyfish Nemopilema nomurai nematocyst venom (NnNV) to skin cells. The expression levels of the three inflammatory factors IL-6, MCP-1, and TNF-α in the cells were also significantly decreased, indicating that MMPs in jellyfish venom are probably vital factors leading to jellyfish dermatitis. This study is beneficial in the prevention and treatment of jellyfish stings.

Insights into individual variations in nematocyst venoms from the giant jellyfish Nemopilema nomurai in the Yellow Sea

The giant jellyfish, Nemopilema nomurai, is widely distributed from the Eastern China Sea to the northern part of the Yellow Sea and has resulted in numerous hospitalizations in coastal areas of China, especially in Northern China. Our previous studies have revealed sting-related proteins in the venom of the jellyfish N. nomurai by using experimental and omics-based approaches; however, the variable symptoms of patients who have been stung by N. nomurai are not fully understood. This limited knowledge led to an examination of whether intraspecific variations occur in the venom of different N. nomurai. In the present study, 13 specimens of N. nomurai were collected from the Yellow Sea, and their venom was characterized by profiling differences in biochemical properties and biological activities. SDS-PAGE analysis presented recognizable differences in the number, intensity and presence of some protein bands. Moreover, enzymatic assays revealed considerable quantitative variations in metalloproteinase activity and PLA₂-like activity. In particular, zymography assays of proteases demonstrated the general presence of abundant metalloproteinases in jellyfish nematocyst venom; however, the catalytic activities varied greatly among some specific metalloproteinases in the 28–46 kDa or 57–83 kDa range. Hemolytic assays using sheep erythrocytes suggested a predominant variance in the toxicities of different individual jellyfish venoms, with the difference between the most hemolytic and the least hemolytic venom as large as 77-fold. The current data suggested remarkable variations in the nematocyst venoms of individual N. nomurai jellyfish. These observations will provide a new understanding of the clinical manifestations induced by N. nomurai jellyfish stings and will therefore have important implications for preventing and treating jellyfish envenomations.

Impact of Scyphozoan Venoms on Human Health and Current First Aid Options for Stings

Cnidaria include the most venomous animals of the world. Among Cnidaria, Scyphozoa (true jellyfish) are ubiquitous, abundant, and often come into accidental contact with humans and, therefore, represent a threat for public health and safety. The venom of Scyphozoa is a complex mixture of bioactive substances—including thermolabile enzymes such as phospholipases, metalloproteinases, and, possibly, pore-forming proteins—and is only partially characterized. Scyphozoan stings may lead to local and systemic reactions via toxic and immunological mechanisms; some of these reactions may represent a medical emergency. However, the adoption of safe and efficacious first aid measures for jellyfish stings is hampered by the diffusion of folk remedies, anecdotal reports, and lack of consensus in the scientific literature. Species-specific differences may hinder the identification of treatments that work for all stings. However, rinsing the sting site with vinegar (5% acetic acid) and the application of heat (hot pack/immersion in hot water) or lidocaine appear to be substantiated by evidence. Controlled clinical trials or reliable models of envenomation are warranted to confirm the efficacy and safety of these approaches and identify possible species-specific exceptions. Knowledge of the precise composition of Scyphozoa venom may open the way to molecule-oriented therapies in the future.

Cnidarian Jellyfish: Ecological Aspects, Nematocyst Isolation, and Treatment Methods of Sting

Cnidarians play an important role in ecosystem functioning, in the competition among species, and for possible utilization of several active compounds against cardiovascular, nervous, endocrine, immune, infective, and inflammatory disorders or having antitumoral properties, which have been extracted from these organisms. Nevertheless, notwithstanding these promising features, the main reason for which cnidarians are known is due to their venomousness as they have a serious impact on public health as well as in economy being able to affect some human activities. For this reason a preeminent subject of the research about cnidarians is the organization of proper systems and methods of care and treatment of stinging. This chapter aims to present the data about the morphological, ecological, toxicological, epidemiological, and therapeutic aspects regarding cnidarians with the purpose to summarize the existing knowledge and to stimulate future perspectives in the research on these organisms.

β adrenergic receptor/cAMP/PKA signaling contributes to the intracellular Ca2+ release by tentacle extract from the jellyfish Cyanea capillata

Background

Intracellular Ca²⁺ overload induced by extracellular Ca²⁺ entry has previously been confirmed to be an important mechanism for the cardiotoxicity as well as the acute heart dysfunction induced by jellyfish venom, while the underlying mechanism remains to be elucidated.

Methods

Under extracellular Ca²⁺-free or Ca²⁺-containing conditions, the Ca²⁺ fluorescence in isolated adult mouse cardiomyocytes pre-incubated with tentacle extract (TE) from the jellyfish Cyanea capillata and β blockers was scanned by laser scanning confocal microscope. Then, the cyclic adenosine monophosphate (cAMP) concentration and protein kinase A (PKA) activity in primary neonatal rat ventricular cardiomyocytes were determined by ELISA assay. Furthermore, the effect of propranolol against the cardiotoxicity of TE was evaluated in Langendorff-perfused rat hearts and intact rats.

Results

The increase of intracellular Ca²⁺ fluorescence signal by TE was significantly attenuated and delayed when the extracellular Ca²⁺ was removed. The β adrenergic blockers, including propranolol, atenolol and esmolol, partially inhibited the increase of intracellular Ca²⁺ in the presence of 1.8 mM extracellular Ca²⁺ and completely abolished the Ca²⁺ increase under an extracellular Ca²⁺-free condition. Both cAMP concentration and PKA activity were stimulated by TE, and were inhibited by the β adrenergic blockers. Cardiomyocyte toxicity of TE was antagonized by β adrenergic blockers and the PKA inhibitor H89. Finally, the acute heart dysfuction by TE was antagonized by propranolol in Langendorff-perfused rat hearts and intact rats.

Conclusions

Our findings indicate that β adrenergic receptor/cAMP/PKA signaling contributes to the intracellular Ca²⁺ overload through intracellular Ca²⁺ release by TE from the jellyfish C. capillata.

Functional Elucidation of Nemopilema nomurai and Cyanea nozakii Nematocyst Venoms' Lytic Activity Using Mass Spectrometry and Zymography

Background: Medusozoans utilize explosively discharging penetrant nematocysts to inject venom into prey. These venoms are composed of highly complex proteins and peptides with extensive bioactivities, as observed in vitro. Diverse enzymatic toxins have been putatively identified in the venom of jellyfish, Nemopilema nomurai and Cyanea nozakii, through examination of their proteomes and transcriptomes. However, functional examination of putative enzymatic components identified in proteomic approaches to elucidate potential bioactivities is critically needed. Methods: In this study, enzymatic toxins were functionally identified using a combined approach consisting of in gel zymography and liquid chromatography tandem mass spectrometry (LC-MS/MS). The potential roles of metalloproteinases and lipases in hemolytic activity were explored using specific inhibitors. Results: Zymography indicated that nematocyst venom possessed protease-, lipase- and hyaluronidase-class activities. Further, proteomic approaches using LC-MS/MS indicated sequence homology of proteolytic bands observed in zymography to extant zinc metalloproteinase-disintegrins and astacin metalloproteinases. Moreover, pre-incubation of the metalloproteinase inhibitor batimastat with N. nomurai nematocyst venom resulted in an approximate 62% reduction of hemolysis compared to venom exposed sheep erythrocytes, suggesting that metalloproteinases contribute to hemolytic activity. Additionally, species within the molecular mass range of 14–18 kDa exhibited both egg yolk and erythrocyte lytic activities in gel overlay assays. Conclusion: For the first time, our findings demonstrate the contribution of jellyfish venom metalloproteinase and suggest the involvement of lipase species to hemolytic activity. Investigations of this relationship will facilitate a better understanding of the constituents and toxicity of jellyfish venom.