Karin Gyufko

Lesional expression of interferon-γ in atopic eczema

Abstract Atopic eczema is thought to be caused by skin-infiltrating CD4 T cells of the Th 1 -like and/or Th 2 -like subtype. We assessed expression of the Th 1 -like cytokine, interferon-γ, and the Th 2 -like cytokine, interleukin-4, in lesional atopic skin. Compared with that in normal skin, interferon-γ and interleukin-4 mRNA expression were increased in eczematous skin lesions in 13 and 4 of 15 patients, respectively. After successful therapy of atopic dermatitis, the increased interferon-γ mRNA expression but not the increased interleukin-4 mRNA expression was significantly downregulated. These data indicate that in-situ expression of interferon-γ is linked to the clinical course of atopic dermatitis.

Prostaglandin E2 Induces Interleukin‐6 Synthesis in Human Astrocytoma Cells

Abstract: Prostaglandins (PGs) and cytokines, such as interleukin‐1 (IL‐1) and interleukin‐6 (IL‐6), have been implicated in the etiopathology of various inflammatory and degenerative disorders, including Alzheimers disease (AD) and prion diseases. Nonsteroidal antiinflammatory drugs (NSAIDs), potent inhibitors of PG synthesis, appear to be beneficial in the treatment of AD. To assess whether PGs are able to induce IL‐6 synthesis in cells of the CNS, IL‐6 mRNA and protein syntheses were measured in a human astrocytoma cell line after stimulation with different PGs. PGE1 and PGE2, but not PGD2 and PGF2α, led to a rapid and transient induction of IL‐6 mRNA, followed by IL‐6 protein synthesis. Furthermore, PGE2 potentiated IL‐1β‐induced IL‐6 mRNA synthesis. These results are discussed with respect to the participation of PGs in neurodegenerative diseases (and its inhibition by NSAIDs) by affecting cytokine expression.

Regulation of the mRNA expression for tumor necrosis factor-α in rat liver macrophages

Kupffer cells are known to produce tumor necrosis factor- α upon stimulation with endotoxin or viruses. This tumor necrosis factor- α synthesis is suppressed by prostaglandin E 2 or dexamethasone. Using Northern blotting and reverse transcriptase-polymerase chain reaction, it is demonstrated that endotoxin-induced tumor necrosis factor- α synthesis is blocked by prostaglandin E 2 or dibutyryl 3′:5′-cyclic adenosine monophosphate on the transcriptional level. Tumor necrosis factor- α itself suppressed endotoxin-evoked tumor necrosis factor- α mRNA expression when given in a narrow time interval with lipopolysaccharide. Interleukin-10 of human or mouse origin also inhibited the synthesis of tumor necrosis factor- α mRNA and protein when given more than 2 h prior to the endotoxin challenge. The suppressive effect of prostaglandin E 2 lasted for more than 36 h while IL-10 blocked tumor necrosis factor- α production for barely 24 h. Dexamethasone reduced the endotoxin-induced tumor necrosis factor- α mRNA formation by approximately 50% only, although it led to nearly complete inhibition of the synthesis of the mature protein. Taken together with reverse transcriptase-polymerase chain reaction data revealing significant amounts of tumor necrosis factor- α mRNA in resting Kupffer cells, an additional posttranscriptional regulation of tumor necrosis factor- α synthesis has to be assumed. Tumor necrosis factor- α mRNA was not induced by interferon- γ , interleukin-1 β or interleukin-6 (the latter two cytokines are also synthesized by Kupffer cells), but a 24-h prestimulation of liver macrophages with interferon- γ or phorbol ester had a modest priming effect. Other substances known to stimulate rat Kupffer cells, such as phorbol ester or calcium ionophore, did not lead to the induction of tumor necrosis factor- α or to an alteration of the lipopolysaccharide-induced tumor necrosis factor- α mRNA synthesis at 90 min or 24 h after stimulation. Comparison with findings on tumor necrosis factor- α mRNA synthesis in some macrophage-related cell lines, monocytes and freshly differentiated macrophages suggests that organ-specific differentiation of resident macrophages leads to variations in the regulation of tumor necrosis factor- α mRNA production.

Studies on synthesis and degradation of eicosanoids by rat hepatocytes in primary culture

The potential of hepatocytes in primary cultures to degrade the prostanoids produced by Kupffer cells and to synthesize eicosanoids, especially leukotriene B4, after treatment with D-galactosamine was studied. Hepatocytes in primary cultures showed a substantial capability to degrade all the prostanoids produced by stimulated Kupffer cells. The rate of degradation, approx. 2 pmol/min per 10(6) hepatocytes, was nearly the same for the prostaglandins D2, E2 and F2a. Lower rates were determined for thromboxane B2 (0.4 pmol/min per 10(6) cells) and for 6-ketoprostaglandin F1a (0.2 pmol/min per 10(6) cells). The degradation products of these prostanoids lacked biological activity, e.g., reactivity with specific antibodies and the ability to contract segments of rabbit femoral artery. In the presence of 30 microM arachidonic acid, hepatocytes produced only very small amounts of prostaglandins and thromboxane, ranging from less than or equal to 22 to 50 fmol/30 min per 10(6) cells. Neither untreated nor D-galactosamine-treated hepatocytes released significant amounts of leukotriene B4. Hepatocytes appear to be the site of degradation rather than synthesis of eicosanoids in the liver.

Net prostaglandin release by perfused rat liver after stimulation with phorbol 12-myristate 13-acetate

Phorbol myristate acetate, which was shown previously to elicit eicosanoid synthesis in primary cultures of Kupffer cells, led to a net release of prostaglandins (PG) D2 and E2 from the perfused rat liver. While a substantial amount of PGD2 (the major prostaglandin of Kupffer cells) left the liver, very little PGE2 was found in the effluent. Considerable amounts of immunologically reactive PGD2 and E2 were secreted with the bile. PGE2 rather than PGD2 was able to stimulate glycogenolysis and to increase perfusion pressure. These effects were, however, strongly dependent on the direction of the flow. If the liver was perfused in a retrograde fashion, i.e., from the vena cava to the portal vein, phorbol myristate acetate or PGE2 exerted only minor effects. These observations suggest a topological heterogeneity of producer and responder cells, respectively, in the liver sinusoid.