Gentamicin suppresses endotoxin-driven TNF- production in human and mouse proximal tubule cells

Zager RA, Johnson AC, Geballe A. Gentamicin suppresses endotoxin-driven TNFproduction in human and mouse proximal tubule cells. Am J Physiol Renal Physiol 293: F1373–F1380, 2007. First published August 15, 2007; doi:10.1152/ajprenal.00333.2007.— Gentamicin is a mainstay in treating gram-negative sepsis. However, it also may potentiate endotoxin (LPS)-driven plasma TNFincreases. Because gentamicin accumulates in renal tubules, this study addressed whether gentamicin directly alters LPS-driven tubular cell TNFproduction. HK-2 proximal tubular cells were incubated for 18 h with gentamicin (10–2,000 g/ml). Subsequent LPS-mediated TNFincreases (at 3 or 24 h; protein/mRNA) were determined. Gentamicin effects on overall protein synthesis ([S]methionine incorporation), monocyte chemoattractant protein-1 (MCP-1) levels, and LPS-stimulated TNFgeneration by isolated mouse proximal tubules also were assessed. Finally, because gentamicin undergoes partial biliary excretion, its potential influence on gut TNF/MCP-1 mRNAs was probed. Gentamicin caused striking, dose-dependent inhibition of LPS-driven TNFproduction (up to 80% in HK-2 cells/isolated tubules). Surprisingly, this occurred despite increased TNFmRNA accumulation. Comparable changes in MCP-1 were observed. These changes were observed at clinically relevant gentamicin concentrations and despite essentially normal overall protein synthetic rates. Streptomycin also suppressed LPS-driven TNFincreases, suggesting an aminoglycoside drug class effect. Gentamicin doubled basal TNFmRNA in cecum and in small intestine after LPS. Gentamicin can suppress LPS-driven TNFproduction in proximal tubule cells, likely by inhibiting its translation. Overall preservation of protein synthesis and comparable MCP-1 suppression suggest a semiselective blockade within the LPS inflammatory mediator cascade. These results, coupled with increases in gut TNF/ MCP-1 mRNAs, imply that gentamicin may exert protean, countervailing actions on systemic cytokine/chemokine production during gram-negative sepsis.