Silica - A trace geogenic element with emerging nephrotoxic potential.

Area of Science:

• Nephrology
• Toxicology
• Cell Biology

Background:

• Silica exposure is linked to pulmonary silicosis and chronic kidney disease (CKD).
• Renal pathophysiological mechanisms of silica toxicity are less understood than pulmonary effects.
• Human kidney proximal-tubular (HK) cells are primary targets for silica toxicity.

Purpose of the Study:

• To elucidate the in-vitro cellular and molecular mechanisms of silica-induced renal pathology.
• To investigate the dose- and time-dependent effects of silica on HK cells.
• To identify key pathways involved in silica-induced nephrotoxicity.

Main Methods:

• In-vitro toxicity assessments on HK cells using MTT assay.
• Analysis of reactive oxygen species (ROS) generation.
• Measurement of pro-inflammatory and fibrogenic cytokines (IL-1β, IL-2, IL-6, TNF-α, TGF-β).
• Comet assay for DNA damage assessment.
• Analysis of cell cycle arrest and apoptosis-related proteins (p53, Bax, cytochrome-c, caspases).

Main Results:

• Silica induced dose- and time-dependent cytotoxicity and cell death in HK cells at concentrations ≥100 mg/L.
• Nephrotoxicity was primarily mediated by silica-induced oxidative stress (ROS).
• Elevated ROS led to inflammation, fibrosis, DNA damage, G2/M arrest, and apoptosis.
• Apoptosis involved p53-mediated mitochondrial pathways via Bax, cytochrome-c, and caspase activation.
• Chronic exposure resulted in tubular atrophy and fibrosis, hallmarks of CKD.

Conclusions:

• Silica exposure at ≥100 mg/L induces CKD through oxidative stress, inflammation, DNA damage, and apoptosis in kidney proximal-tubular cells.
• Understanding these mechanisms provides insights for developing therapeutic strategies against silica-induced CKD.
• Targeting ROS could be a potential therapeutic approach to mitigate silica-induced kidney damage.