Microcystin-Induced Immunotoxicity in Fishes: A Scoping Review

Abstract

Cyanobacteria (blue-green algae) have been present on Earth for over 2 billion years, and can produce a variety of bioactive molecules, such as cyanotoxins. Microcystins (MCs), the most frequently detected cyanotoxins, pose a threat to the aquatic environment and to human health. The classic toxic mechanism of MCs is the inhibition of the protein phosphatases 1 and 2A (PP1 and PP2A). Immunity is known as one of the most important physiological functions in the neuroendocrine-immune network to prevent infections and maintain internal homoeostasis in fish. The present review aimed to summarize existing papers, elaborate on the MC-induced immunotoxicity in fish, and put forward some suggestions for future research. The immunomodulatory effects of MCs in fish depend on the exposure concentrations, doses, time, and routes of exposure. Previous field and laboratory studies provided strong evidence of the associations between MC-induced immunotoxicity and fish death. In our review, we summarized that the immunotoxicity of MCs is primarily characterized by the inhibition of PP1 and PP2A, oxidative stress, immune cell damage, and inflammation, as well as apoptosis. The advances in fish immunoreaction upon encountering MCs will benefit the monitoring and prediction of fish health, helping to achieve an ecotoxicological goal and to ensure the sustainability of species. Future studies concerning MC-induced immunotoxicity should focus on adaptive immunity, the hormesis phenomenon and the synergistic effects of aquatic microbial pathogens.

Incorporating Microbial Species Interaction in Management of Freshwater Toxic Cyanobacteria: A Systems Science Challenge

“…HBF can also promote and/or benefit from toxic cyanobacteria via food web interactions. For example, by infecting grazers of cyanobacteria, pathogenic or parasitic HBF can lower the grazers' ability to withstand cyanobacterial toxins and lack of nutritional value [87]. Similarly, they can benefit from their hosts becoming immunocompromised due to exposure to HABs [88][89][90].…”

Meta-analysis reveals cyanotoxins risk across African inland waters

“…MCs also appear to have tumor-promoting properties [26]. In addition, these toxins can cause neurotoxicity [27], developmental toxicity [28], and immunotoxicity [29]. MCs-exposure can cause harm to human health to differing extents.…”

Devosia lacusdianchii sp. nov., an attached bacterium inhibited by metabolites from its symbiotic algae

“…Microcystis aeruginosa is the most frequent species of water bloom-causing cyanobacteria (Park et al 2009), and the main producer of microcystins (MCs) that include a family of hepatotoxins (Dawson 1998). Over 270 different derivatives of MCs have been identi ed (Lin et al 2021), of which MC-LR is the most common and toxic type in both natural cyanobacterial bloom (Vasconcelos et al 1996)d aeruginosa culture of laboratory (Liu et al 2012).…”