Brevetoxin PbTx2 Modulates Oxidative Stress and Inflammatory Response in an In Vitro Human Immune Cell Line

Brevetoxins (PbTx) exert detrimental effects on marine organisms and humans, mainly through alterations in immune cell function. This study evaluated the immunotoxic potential of sublethal concentrations of PbTx-2 using the THP-1 human monocyte cell line as an in vitro model. Cell viability assessed by the MTT assay revealed an IC₅₀ of 8.99 µM at 24 h, while exposures to 2.8 and 5.6 µM for 4 and 8 h did not affect viability. Immune and oxidative responses were examined through antioxidant activity and transcript expression by qPCR. PbTx-2 exposure altered the expression of catalase, glutathione reductase, interleukin IL-8, IL-1β, and TNF-α. Although reactive oxygen species (ROS) levels remained unchanged, catalase activity and Cu/Zn-superoxide dismutase activity decreased after 8 h. These results indicate that PbTx-2 modulates redox and inflammatory pathways in THP-1 cells, even under non-cytotoxic conditions. The observed sublethal effects suggest potential immunomodulatory consequences of brevetoxin exposure. More studies are needed to determine whether chronic low-level exposure to brevetoxins could contribute to immune dysfunction or inflammatory pathologies in humans and marine mammals.