Cytotoxic and immunotoxic profile of HgCl2 involves alterations in purinergic signaling through the P2X7/NLRP3/CASP-1/IL-1β pathway: An in vitro study using human blood immune cells.

An in vitro model using human peripheral blood mononuclear cells (PBMCs) was established to investigate the cytotoxic, oxidative and inflammatory effects and changes in purinergic system parameters caused by mercuric chloride (HgCl2). Cells were exposed to concentrations of HgCl2 (0.05, 0.5, 5, and 50 μM) for 24, 48 and 72 h. Cell viability was measured by trypan blue and MTT assays, and IC50; apoptosis and cell death were assessed by flow cytometry. Oxidative stress was evaluated by reactive species (RS) generation, determination of Mercury (ICP-MS), Nitric Oxide (NO), and lipid peroxidation. Increased levels of HgCl₂ induced RS generation, NO, lipid peroxidation, apoptosis, and altered the cell cycle, reducing DNA synthesis and cell division of PBMCs. Flow cytometry confirmed decreased viability and increased late apoptosis. HgCl₂ accumulation in PBMCs was confirmed by ICP-MS. HgCl₂ altered purinergic system components, inhibiting NTPDase and increasing ADA activity. At 5 μM, it increased gene expression of purinergic receptors and both anti-inflammatory (IL-10) and pro-inflammatory markers (IL-1β, IL-6, TNF-α, NLRP3, CASP-1, NF-κB). Overexpression of the P2X7/NLRP3/CASP-1/IL-1β axis triggered cell death by pyroptosis. These findings provide compelling evidence HgCl2 induces cytotoxic and inflammatory effects in PBMCs.