Donald T. Forman

Estrogen increases sensitivity of hepatic Kupffer cells to endotoxin.

The relationship among gender, lipopolysaccharide (LPS), and liver disease is complex. Accordingly, the effect of estrogen on activation of Kupffer cells by endotoxin was studied. All rats given estrogen intraperitoneally 24 h before an injection of a sublethal dose of LPS (5 mg/kg) died within 24 h, whereas none of the control rats died. Mortality was prevented totally by pretreatment with gadolinium chloride, a Kupffer cell toxicant. Peak serum tumor necrosis factor-α (TNF-α) values as well as TNF-α mRNA in the liver after LPS were twice as high in the estrogen-treated group as in the untreated controls. Plasma nitrite levels and inducible nitric oxide synthase in the liver were also elevated significantly in estrogen-treated rats 6 h after LPS. Furthermore, Kupffer cells isolated from estrogen-treated rats produced about twice as much TNF-α and nitrite as controls did in response to LPS. In addition, Kupffer cells from estrogen-treated rats required 15-fold lower amounts of LPS to increase intracellular Ca2+ than controls did, and Kupffer cells from estrogen-treated animals expressed more CD14, the receptor for LPS/LPS binding protein, than controls. Moreover, estrogen treatment increased LPS binding protein mRNA dramatically in liver in 6-24 h. It is concluded that estrogen treatment in vivo sensitizes Kupffer cells to LPS, leading to increased toxic mediator production by the liver.The relationship among gender, lipopolysaccharide (LPS), and liver disease is complex. Accordingly, the effect of estrogen on activation of Kupffer cells by endotoxin was studied. All rats given estrogen intraperitoneally 24 h before an injection of a sublethal dose of LPS (5 mg/kg) died within 24 h, whereas none of the control rats died. Mortality was prevented totally by pretreatment with gadolinium chloride, a Kupffer cell toxicant. Peak serum tumor necrosis factor-alpha (TNF-alpha) values as well as TNF-alpha mRNA in the liver after LPS were twice as high in the estrogen-treated group as in the untreated controls. Plasma nitrite levels and inducible nitric oxide synthase in the liver were also elevated significantly in estrogen-treated rats 6 h after LPS. Furthermore, Kupffer cells isolated from estrogen-treated rats produced about twice as much TNF-alpha and nitrite as controls did in response to LPS. In addition, Kupffer cells from estrogen-treated rats required 15-fold lower amounts of LPS to increase intracellular Ca2+ than controls did, and Kupffer cells from estrogen-treated animals expressed more CD14, the receptor for LPS/LPS binding protein, than controls. Moreover, estrogen treatment increased LPS binding protein mRNA dramatically in liver in 6-24 h. It is concluded that estrogen treatment in vivo sensitizes Kupffer cells to LPS, leading to increased toxic mediator production by the liver.

The role of gut-derived bacterial toxins and free radicals in alcohol-induced liver injury.

Previous research from this laboratory using a continuous enteral ethanol (EtOH) administration model demonstrated that Kupffer cells are pivotal in the development of EtOH‐induced liver injury. When Kupffer cells were destroyed using gadolinium chloride (GdCl3) or the gut was sterilized with polymyxin B and neomycin, early inflammation due to EtOH was blocked. Anti‐tumour necrosis factor (TNF)‐α antibody markedly decreased EtOH‐induced liver injury and increased TNF‐mRNA. These findings led to the hypothesis that EtOH‐induced liver injury involves increases in circulating endotoxin leading to activation of Kupffer cells. Pimonidazole, a nitro‐imidazole marker, was used to detect hypoxia in downstream pericentral regions of the lobule. Following one large dose of EtOH or chronic enteral EtOH for 1 month, pimonidazole binding was increased significantly in pericentral regions of the liver lobule, which was diminished with GdCl3. Enteral EtOH increased free radical generation detected with electron spin resonance (ESR). These radical species had coupling constants matching α‐hydroxyethyl radical and were shown conclusively to arise from EtOH based on a doubling of the ESR lines when 13C‐EtOH was given. α‐Hydroxyethyl radical production was also blocked by the destruction of Kupffer cells with GdCl3. It is known that females develop more severe EtOH‐induced liver injury more rapidly and with less EtOH than males. Female rats on the enteral protocol exhibited more rapid injury and more widespread fatty changes over a larger portion of the liver lobule than males. Plasma endotoxin, ICAM‐1, free radical adducts, infiltrating neutrophils and transcription factor NFκB were approximately two‐fold greater in livers from females than males after 4 weeks of enteral EtOH treatment. Furthermore, oestrogen treatment increased the sensitivity of Kupffer cells to endotoxin. These data are consistent with the hypothesis that Kupffer cells participate in important gender differences in liver injury caused by ethanol.

The Biochemistry of Reye's Syndrome

AbstractAnd I Daniel fainted, and was sick certain days; afterward I rose up, and did the kings business; and I was astonished at the vision, but none understood it.The Bible Daniel 8:27On the basis of the findings presented in this biochemical overview, it can be said that Reyes syndrome affects every major category of human metabolism. Such an effect at the molecular level parallels, in scope, the known impact of this disease on the function and/or structure of parenchymal cells from multiple organ systems. In this regard, the student of RS is presented with a unique opportunity to examine, integrate, and correlate a spectrum of morphopathologic and pathophysiologic findings with biochemical derangements as we have attempted to do. An appreciation of the complex interplay of these structural, functional, and biochemical abnormalities and how they might perpetuate or accelerate the disease process would be educationally rewarding in itself. Moreover, because we are handicapped from a therapeutic standp...AbstractAnd I Daniel fainted, and was sick certain days; afterward I rose up, and did the kings business; and I was astonished at the vision, but none understood it.The Bible Daniel 8:27On the basis of the findings presented in this biochemical overview, it can be said that Reyes syndrome affects every major category of human metabolism. Such an effect at the molecular level parallels, in scope, the known impact of this disease on the function and/or structure of parenchymal cells from multiple organ systems. In this regard, the student of RS is presented with a unique opportunity to examine, integrate, and correlate a spectrum of morphopathologic and pathophysiologic findings with biochemical derangements as we have attempted to do. An appreciation of the complex interplay of these structural, functional, and biochemical abnormalities and how they might perpetuate or accelerate the disease process would be educationally rewarding in itself. Moreover, because we are handicapped from a therapeutic standp...

Role of Kupffer Cells, Endotoxin and Free Radicals in Hepatotoxicity Due to Prolonged Alcohol Consumption: Studies in Female and Male Rats

Alcohol ingestion results in increases in the release of endotoxin from gut bacteria or membrane permeability of the gut to endotoxin, or both. Female rats are more sensitive to these changes. Elevated levels of endotoxin activate Kupffer cells to release substances such as eicosanoids, tumor necrosis factor-alpha and free radicals. Prostaglandins increase oxygen uptake and most likely are responsible for the hypermetabolic state in the liver. The increase in oxygen demand leads to hypoxia in the liver, and on reperfusion, alpha-hydroxyethyl free radicals are formed that lead to tissue damage in oxygen-poor pericentral regions of the liver lobule.

Reduction of ciclosporin and tacrolimus nephrotoxicity by plant polyphenols

The immunosuppressants ciclosporin (cyclosporin A, CsA) and tacrolimus can cause severe nephrotoxicity. Since CsA increases free radical formation, this study investigated whether an extract from Camellia sinensis, which contains several polyphenolic free radical scavengers, could prevent nephrotoxicity caused by CsA and tacrolimus. Rats were fed powdered diet containing polyphenolic extract (0‐0.1%) starting 3 days before CsA or tacrolimus. Free radicals were trapped with α‐(4‐pyridyl‐1‐oxide)‐N‐tert‐butylnitrone (POBN) and measured using an electron spin resonance spectrometer. Both CsA and tacrolimus decreased glomerular filtration rates (GFR) and caused tubular atrophy, vacuolization and calcification and arteriolar hyalinosis, effects that were blunted by treatment with dietary polyphenols. Moreover, CsA and tacrolimus increased POBN/radical adducts in urine nearly 3.5 fold. Hydroxyl radicals attack dimethyl sulfoxide (DMSO) to produce a methyl radical fragment. Administration of CsA or tacrolimus with 12C‐DMSO produced a 6‐line spectrum, while CsA or tacrolimus given with 13C‐DMSO produced a 12‐line ESR spectrum, confirming formation of hydroxyl radicals. 4‐Hydroxynonenal (4‐HNE), a product of lipid peroxidation, accumulated in proximal and distal tubules after CsA or tacrolimus treatment. ESR changes and 4‐HNE formation were largely blocked by polyphenols. Taken together, these results demonstrate that both CsA and tacrolimus stimulate free radical production in the kidney, most likely in tubular cells, and that polyphenols minimize nephrotoxicity by scavenging free radicals.

Inhibition of ethanol metabolism by fructose in alcohol dehydrogenase-deficient deer mice in vivo

The purpose of this work was to compare the roles of a newly described mitochondrial dehydrogenase and catalase in ethanol elimination in deer mice deficient in alcohol dehydrogenase (ADH-). Fructose was used because of its well-known ability to stimulate dehydrogenase-dependent ethanol metabolism. Rates of ethanol metabolism in vivo were decreased significantly by about 60% in a dose-dependent manner by fructose in deer mice fed an ethanol-containing or a corn oil control diet. In addition, rates of metabolism of methanol, a selective substrate for catalase in rodents, were similar to rates of ethanol elimination and were decreased from 6.9 +/- 1.0 to 1.7 +/- 0.5 mmol/kg/h by fructose, supporting the hypothesis that catalase and not a mitochondrial dehydrogenase predominates in ethanol oxidation in ADH-deer mice. Glycolate, a substrate for peroxisomal H2O2 generation, reversed the inhibition of alcohol metabolism by fructose completely, indicating that fructose did not inhibit catalase directly. As expected, the ATP/ADP ratio was decreased by fructose significantly from 4.2 +/- 0.4 to 2.4 +/- 0.4 in deer mouse livers. These data are consistent with the hypothesis that fructose decreases catalase-dependent ethanol metabolism in vivo by inhibiting hepatic H2O2 generation.

Proteolyse aber nicht ICAM-1 Expression ist in Fettlebern während der Organentnahme erhöht--Rolle der Kupfferzellen.

Der Mangel an Spenderorganen ist trotz massiver Bemuhungen um eine Expansion des Spenderaufkommens eines der dringlichsten Probleme der Transplantation. Bessere Methoden zur Spenderevaluation werden dringend benotigt, um marginale Transplantate mit erhohtem Risiko fur Versagen oder Dysfunktion fruhzeitig erkennen zu konnen, ohne alle marginalen Lebern von einer Transplantation auszuschliesen [1,2].