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Microcystin-LR modulates selected immune parameters and induces necrosis/apoptosis of carp leucocytes
Anna Rymuszka1, Anna Sierosławska, Adam Bownik
1Department of Physiology and Ecotoxicology, The John Paul II Catholic University of Lublin, 14 Al. Racławickie str, Lublin, Poland. anrym@kul.lublin.pl
Abstract:
Microcystins (MCs) are potent hepatotoxins acting by the inhibition of protein phosphatase 1 and 2A, and may promote liver tumors. Moreover, studies also suggest they are nephrotoxic. The aim of the present study was to assess possible in vitro effects of microcystin-LR (which contains the amino acids leucine and arginine, the most widely studied and distributed variant of all microcystins) on the selected immune functions of the cells isolated from the head kidney of carp. In the experiments, pure microcystin-LR (MC-LR), was used at concentrations of 0.01, 0.1, 0.5, and 1 microg/ml RPMI-1640 medium. Leucocytes (lymphocytes and phagocytes) were isolated by centrifugation on a density gradient. Lymphocyte proliferation, intracellular production of reactive oxygen species by phagocytes, and the presence of apoptotic and/or necrotic cells were assessed. The respiratory burst activity of phagocytic cells was increased at the lowest toxin concentration used in the study, but it was decreased at higher concentrations. Using a sensitive luminescent immunoassay, MC-LR was observed to have no influence on the T-cell proliferation but decreased the proliferation of B lymphocytes. Moreover, it was noted that MC-LR induced necrosis to a higher degree than apoptosis in fish leucocytes. The results of the present study suggest the modulatory potency of microcystin-LR on fish leucocytes.
Insights
Microcystin-LR (MC-LR) affects fish immune cells. This potent hepatotoxin alters phagocyte activity and reduces B lymphocyte proliferation, while inducing necrosis more than apoptosis in carp leucocytes.
Area of Science:
- Environmental toxicology
- Immunology
- Aquatic animal health
Background:
- Microcystins (MCs) are cyanotoxins known for hepatotoxicity and potential carcinogenicity.
- Emerging evidence suggests microcystins also exhibit nephrotoxic effects.
- The impact of MC-LR on fish immune systems, particularly leucocytes, requires further investigation.
Purpose of the Study:
- To investigate the in vitro effects of microcystin-LR (MC-LR) on carp head kidney leucocyte functions.
- To assess MC-LR's influence on lymphocyte proliferation, phagocyte respiratory burst activity, and cell death.
- To determine the specific mechanisms of MC-LR toxicity on fish immune cells.
Main Methods:
- Isolation of leucocytes (lymphocytes and phagocytes) from carp head kidney using density gradient centrifugation.
- Exposure of leucocytes to varying concentrations of pure MC-LR (0.01–1 µg/ml).
- Assessment of T-cell and B-cell proliferation, phagocyte respiratory burst activity, and apoptosis/necrosis using luminescent immunoassay and other methods.
Main Results:
- Phagocyte respiratory burst activity initially increased at low MC-LR concentrations but decreased at higher concentrations.
- MC-LR did not affect T-cell proliferation but significantly reduced B lymphocyte proliferation.
- MC-LR induced higher levels of necrosis compared to apoptosis in fish leucocytes.
Conclusions:
- Microcystin-LR modulates key immune functions in fish leucocytes.
- The observed effects suggest potential immunosuppression and cellular damage in fish exposed to MC-LR.
- These findings highlight the immunotoxic potential of microcystins in aquatic organisms.
