The venom and the toxicity of Pelagia noctiluca (Cnidaria: Scyphozoa). A review of three decades of research in Italian laboratories and future perspectives

Abstract

Recurrent outbreaks of Pelagia noctiluca and health problems consequent to stings were recorded during the last decades. This phenomenon forced some Italian University laboratories to study this cnidarian. The first studies concerned the distribution, biochemical composition and morphology of nematocysts of Pelagia noctiluca. The discharge mechanism of nematocysts was defined starting from early 1980s when enzymes, cations, anions, and pH were observed to have an influence on this process. Notably, trypsin, extreme pH values, some anions (I -, Cl -, SCN -), and thioglycolate were seen to induce, while La 3+ and Gd 3+ to prevent, nematocyst discharge. The discharge of both in situ and isolated nematocyst was found to be Ca 2+ dependent. Furthermore, Pelagia noctiluca nematocysts were seen to retain their discharging capacity in distilled water. The toxicological evaluations were carried out mainly using the crude venom from Pelagia noctiluca because, unfortunately, to date the composition of venom remains unknown. Hemolytic and cytotoxic properties of crude venom have been evaluated on erythrocytes and cultured guinea-pig fibroblasts, mouse fibroblasts, and cancer (neuroblastoma) cells. The activity of Pelagia noctiluca venom on other cnidarians has been also assessed. The crude venom induced apoptosis by reactive oxygen species generation and decrease in mitochondrial transmembrane potential, loss of mitochondrial integrity, and alteration of cell membrane permeability. A pore-forming action mechanism on mitochondrial membrane with oxidative damage was also suggested. The protective activity of some compounds against envenomations has been also evaluated. Future challenges will concern the attempts to characterize the venom and to perform a wider screening of cytotoxicity induced to normal and cancer cells.

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

“…With specific regard to Scyphozoa, deionized water was found to be ineffective for C. quinquecirrha ( Table 1 ). Distilled water did not prevent nematocyst discharge in P. noctiluca [ 123 ]. Other authors have strongly recommended avoiding freshwater as the osmotic or pressure changes may trigger discharge of unfired nematocysts [ 31 ].…”

Inhibitory effect of plant extracts on the cytotoxicity of eurytele nematocysts from <em>Pelagia noctiluca</em>

“…23 In this context, we must also consider that fibroblasts can be thought as a reliable cell model to study the effects of nematocysts on epithelial and dermal tissues. 24 The present data show that extracts from A. comosus and C. papaya are able to protect cells against injury induced by nematocyst venom from the jellyfish P. noctiluca, which is known to be cytotoxic, 25 with the extract from C. papaya showing a remarkable activity already at low concentrations, suggesting that this plant could be interesting for anti-venom applicative purposes.…”

How human health and well-being depends on healthy marine habitats in the Mediterranean: A review

“…However, whereas sharks are in decline due to overfishing [ 72 ], some venomous and toxic species are on the rise due to global climate change. This is the case with stinging jellyfish species such as Pelagia noctiluca [ 73 ], and HABs such as those produced by the benthic dinoflagellate Ostreopsis spp [ 71 ]. The latter produces a range of toxins (including palytoxin) that pose a risk for public health: HABs involving this dinoflagellate have been linked to sporadic acute respiratory symptoms and general malaise among people on a number of Mediterranean beaches who were exposed to marine aerosols [ 74 ].…”