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Scheuer, Hartmut, Wilfried Gwinner, Jan Hohbach, Elisabeth F. Grone, Ralf P. Brandes, Ernst Malle, Christoph J. Olbricht, Autar K. Walli, and Hermann-Josef Grone. Oxidant stress in hyperlipidemia-induced renal damage. Am. J. Physiol. Renal Physiol. 278: F63-F74, 2000.--Hyperlipoproteinemia can aggravate glomerulosclerosis and chronic tubulointerstitial (ti) damage in kidneys without primary immunologic disease. We evaluated whether the effect of hyperlipidemia on progression of renal damage differed between kidneys without preexisting glomerular disease and kidneys with mesangioproliferative glomerulonephritis and whether the renal actions of hyperlipidemia were dependent on oxidant-antioxidant balance. Hyperlipidemia was induced by high-fat and high-cholesterol diet in uninephrectomized rats. In rats without glomerulonephritis, hyperlipidemia led to a rise in glomerular and ti generation of reactive oxygen species (ROS). Oxygen radicals were mainly generated by enhanced xanthine oxidoreductase (XO), which rose with protein concentration and activity during hyperlipidemia; concurrently, glomerulosclerosis and chronic ti injury were noticed during hyperlipidemia [ti damage (% of total tubulointerstitium (TI) after 150 days): normolipidemia 0.1 [+ or -] 0% vs. hyperlipidemia 3.4 [+ or -] 0.9%; P [is less than] 0.05]. In mesangioproliferative Thy-1 nephritis, ti injury was significantly accelerated by hyperlipidemia (ti damage after 150 days: normolipidemic Thy-1 nephritis 2.5 [+ or -] 0.6% vs. hyperlipidemic Thy-1 nephritis 12.5 [= or -] 3.1%; P [is less than] 0.05). Antioxidant enzyme activities decreased and XO activity rose markedly in the TI (XO activity in TI after 150 days: normolipidemic Thy-1 nephritis 2.2 [+ or -] 0.5 vs. hyperlipidemic Thy-1 nephritis 4.5 [+ or -] 0.7 cpm/[micro]g protein; P [is less than] 0.05). In hyperlipidemic Thy-1 nephritis rats, which had a higher urinary protein excretion than normolipidemic rats, hypochlorite-modified proteins, an indirect measure for enhanced myeloperoxidase activity, were detected in renal tissue and in urine, respectively. During hyperlipidemia, chronic damage increased in renal TI. Enhanced generation of ROS, rise in oxidant enzyme activity, and generation of hypochlorite-modified proteins in renal tissue and urine were noticed. These data suggest that oxidant stress contributed to the deleterious effects of hyperlipidemia on the renal TI. glomerulonephritis; interstitial fibrosis; proteinuria; reactive oxygen species; tubular atrophy

Cultured primary human keratinocytes were screened for their expression of various members of the toll-like receptor (TLR) family. Keratinocytes were found to constitutively express TLR1, TLR2, TLR3, TLR5, and TLR9 but not TLR4, TLR6, TLR7, TLR8, or TLR10 as shown by polymerase chain reaction analysis. The expression of the crucial receptor for signaling of staphylococcal compounds TLR2 was also confirmed by immunohistochemistry, in contrast to TLR4, which showed a negative staining pattern. Next, we analyzed the activation of the proinflammatory nuclear transcription factor κB by Staphylococcus aureus strain 8325-4. Using nuclear extract gel shifts, RelA staining, and luciferase reporter transfection plasmids we found a clear induction of nuclear factor κB translocation by the bacteria. This translocation induced the transcription of nuclear factor κB controlled genes such as inducible nitric oxide synthetase, COX2, and interleukin-8. Transcription of these genes was followed by production of increased amounts of interleukin-8 protein and NO. Inhibition experiments using monoclonal antibodies and the specific platelet activating factor receptor inhibitor CV3988 showed that nuclear factor κB activation by S. aureus was TLR2 but not TLR4 or platelet activating factor receptor dependent. In line, the purified staphylococcal cell wall components lipoteichoic acid and peptidoglycan, known to signal through TLR2, also showed nuclear factor κB translocation in human keratinocytes, indicating a crucial role of the staphylococcal cell wall in the innate immune stimulation of human keratinocytes. These results help to explain the complex activation of human keratinocytes by S. aureus and its cell wall components in various inflammatory disorders of the skin. [ABSTRACT FROM AUTHOR]

Statins, which are effective lipid-lowering drugs, also possess anti-inflammatory potential. However, circulating lipoproteins may also play a protective role during acute inflammatory diseases because of their ability to bind bacterial toxins. Low cholesterol levels have been reported in inflammatory conditions, and plasma cholesterol concentrations inversely correlate with severity and clinical outcome in septic patients. It is thus paradoxical that statins, which drastically reduce circulating cholesterol levels, should be beneficial in patients with inflammatory disease who are already hypocholesterolemic. We investigated the effect of simvastatin on LPS-induced nuclear factor kappaB (NF-kappaB) activation, TNF release, and mortality in guinea pigs, an animal model with a lipoprotein profile and pattern similar to humans. In the present study, simvastatin reduced circulating total and low-density lipoprotein cholesterol levels by 68% and 76%, respectively, and LPS-induced mortality from 73% to 20%. This reduction was accompanied by a significant reduction of NF-kappaB activation in the liver tissue, splenocytes, and plasma TNF levels by about 80%, 50%, and 77%, respectively. Our data suggest that simvastatin, despite lowering circulating low-density lipoprotein cholesterol, decreased LPS toxicity by reduction of NF-kappaB activation and subsequent release of TNF by modulating 3-hydroxy-3-methylglutaryl coenzyme A reductase activity and therefore deserves consideration as a possible adjuvant therapy in acute inflammatory disease.

Cultured primary human keratinocytes were screened for their expression of various members of the toll-like receptor (TLR) family. Keratinocytes were found to constitutively express TLR1, TLR2, TLR3, TLR5, and TLR9 but not TLR4, TLR6, TLR7, TLR8, or TLR10 as shown by polymerase chain reaction analysis. The expression of the crucial receptor for signaling of staphylococcal compounds TLR2 was also confirmed by immunohistochemistry, in contrast to TLR4, which showed a negative staining pattern. Next, we analyzed the activation of the proinflammatory nuclear transcription factor kappaB by Staphylococcus aureus strain 8325-4. Using nuclear extract gel shifts, RelA staining, and luciferase reporter transfection plasmids we found a clear induction of nuclear factor kappaB translocation by the bacteria. This translocation induced the transcription of nuclear factor kappaB controlled genes such as inducible nitric oxide synthetase, COX2, and interleukin-8. Transcription of these genes was followed by production of increased amounts of interleukin-8 protein and NO. Inhibition experiments using monoclonal antibodies and the specific platelet activating factor receptor inhibitor CV3988 showed that nuclear factor kappaB activation by S. aureus was TLR2 but not TLR4 or platelet activating factor receptor dependent. In line, the purified staphylococcal cell wall components lipoteichoic acid and peptidoglycan, known to signal through TLR2, also showed nuclear factor kappaB translocation in human keratinocytes, indicating a crucial role of the staphylococcal cell wall in the innate immune stimulation of human keratinocytes. These results help to explain the complex activation of human keratinocytes by S. aureus and its cell wall components in various inflammatory disorders of the skin.