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Biomedical subjects

V Kaever

Publications and source records attributed to V Kaever.

At least 19 recordsLinked to original sources
PubMed2006

Intraabdominal tissue concentration of ertapenem.

OBJECTIVES: Ertapenem, a class I carbapenem, is approved for the treatment of mild to severe intraabdominal infections, but its in vivo concentrations in intraabdominal tissues are unknown. The purpose of this study was to determine the concentration of ertapenem in intraabdominal tissue. PATIENTS AND METHODS: After informed consent 48 patients, 23 female and 25 male with a median age of 58 years (34-81), requiring surgical intervention at intraabdominal organs were enrolled. Patients received 1 g of ertapenem intravenously for perioperative prophylaxis. Tissue samples were taken after resection of parts of the organs. Plasma samples were taken when tissue samples were taken. Drug concentrations were determined by liquid chromatography/mass spectrometry. An ANCOVA test (analysis of covariance) was performed to assess organ-specific differences in ertapenem concentration and penetration ratios. RESULTS: Mean+/-SD ertapenem tissue concentration (mg/kg) was 16.0+/-8.8 in the gall bladder, 12.1+/-5.3 in the colon, 7.0+/-5.7 in the small bowel, 4.5+/-2.3 in the liver and 3.4+/-2.9 in the pancreas. The mean tissue/plasma ratio was 0.19 (colon), 0.17 (small bowel), 0.17 (gall bladder), 0.088 (liver) and 0.095 (pancreas). The ANCOVA test revealed statistically significant organ-specific differences in ertapenem tissue concentration in the gall bladder versus liver/pancreas and in tissue penetration for the colon versus liver/pancreas. CONCLUSIONS: These pharmacokinetic results support the assumption that ertapenem is suitable for the treatment of intraabdominal infections.

Abdomen↗
PubMed2001

Comparative study analyzing effects of sirolimus-cyclosporin and sirolimus-tacrolimus combinations on bile flow in the rat.

The new immunosuppressive agent sirolimus is combined in transplant patients with the cholestatic substances cyclosporin and tacrolimus. Nothing is known about possible cholestatic effects of these combinations. Therefore, we compared their effects on bile flow and on important bile parameters in an acute bile fistula model in rats. Cyclosporin reduced bile flow, biliary excretion of bile salts, cholesterol, and GSH to 20-40% of basal values. Sirolimus decreased bile flow to 50% and excretion of GSH to 30% of the initial conditions but had no effect on cholesterol and bile salt excretion. In contrast, tacrolimus increased bile flow to 120% and GSH excretion to 220% of the basal levels. Sirolimus/cyclosporin decreased bile flow and bile parameters to the same extent as cyclosporin alone. Sirolimus/tacrolimus reversed sirolimus-induced reduction of bile flow and GSH excretion and resulted in a normal bile salt and cholesterol excretion, thus it may be the better alternative in cholestatic patients.

Animals↗
PubMed2000

Prostaglandin E2 is variably induced by bacterial superantigens in bovine mononuclear cells and has a regulatory role for the T cell proliferative response.

Signal transduction in antigen presenting cells via MHC class II molecules induces production of prostaglandin E2 (PGE2) known to possess immunoregulatory potential. Since Staphylococcus aureus superantigens (SAgs) utilize MHC class II molecules as primary ligands, we wanted to know whether PGE2 is induced after in vitro SAg stimulation of bovine blood mononuclear cells (boMNC), and whether this arachidonic acid metabolite modulates the preferential SAg-induced proliferative response of bovine CD8+ T cells. SEB as well as SEA induced maximal amounts of PGE2 on day 2 of culture (1-2.5 x 10(-8) mol/l per 2 x 10(5) boMNC). PGE2 production could be inhibited completely by indomethacin (10(-5) mol/l) causing enhanced proliferation of boCD4+ T cells (174%) as well as of boCD8+ T cells (122%) between day 4 and 6 of the in vitro culture, however, only in a subset of the tested animals. Notably, the striking preference of proliferation of boCD8+ over boCD4+ T cells following SAg stimulation remained largely unchanged after inhibition of endogenous PGE2 synthesis or after addition of exogenous PGE2. Higher concentrations of exogenously added PGE2 (> or = 10(-8) mol/l) inhibited the proliferation reaction, mainly due to an increased death rate of both CD4+ and CD8+ blasts. In contrast, lower PGE2 concentrations between 10(-8)-10(-9) mol/l even slightly enhanced the proliferation of both T cell subsets, depending on the individual cell donor. Summing up: These data show that SAgs, indeed, can induce PGE2 production in boMNC which can enhance or reduce the proliferative response of bovine CD4+ and CD8+ T cells.

Animals↗
PubMed2000

Solubilization, partial purification and photolabeling of the integral membrane protein lysophospholipid:acyl-CoA acyltransferase (LAT).

In the present study, we defined experimental conditions that allowed the extraction of the integral membrane protein lysophospholipid:acyl-CoA acyltransferase (LAT, EC 2.3.1.23) from membranes while maintaining the full enzyme activity using the nonionic detergent n-octyl glucopyranoside (OGP) and solutions of high ionic strength. We found that the optimal OGP concentration depended on the ionic strength of the solubilization buffer. Fluorescence measurements with 1,6-diphenyl-1,3,5-hexatriene indicated that the critical micellar concentration (CMC) of OGP decreased with increasing salt concentrations. Analogous studies revealed that the zwitterionic detergent Chaps was ineffective in extracting LAT from membranes in the absence of salt, whereas its solubilization efficiency increased with increasing salt concentrations. Detailed lipid analysis of the different protein/lipid/detergent mixed micelles showed that the protein/lipid/OGP mixed micelles were relatively enriched with sphingomyelin (SPM) compared to protein/lipid/Chaps mixed micelles, indicating that the differences in the solubilization efficiency may be due to the ability to extract more SPM from membranes. When the protein/lipid/OGP mixed micelles were dissociated into protein/detergent and lipid/detergent complexes by the addition of increasing Chaps concentrations, one-tenth of the LAT enzyme activity was preserved making the enzyme accessible to protein purification. Analysis by native PAGE revealed that in the presence of excess Chaps a high molecular mass protein complex migrated into the gel which could be photolabeled by 125I-labelled-18-(4'-azido-2'-hydroxybenzoylamino)-oleyl-CoA. This fatty acid analogue has been shown to be a competitive inhibitor of LAT enzyme activity in the dark, and an irreversible inhibitor after photolysis. Therefore, this protein complex is assumed to contain the LAT enzyme.

Acyltransferases↗
PubMed1999

The two calcium-binding proteins, S100A8 and S100A9, are involved in the metabolism of arachidonic acid in human neutrophils.

Recently, we identified the two myeloid related protein-8 (MRP8) (S100A8) and MRP14 (S100A9) as fatty acid-binding proteins (Klempt, M., Melkonyan, H., Nacken, W., Wiesmann, D., Holtkemper, U., and Sorg, C. (1997) FEBS Lett. 408, 81-84). Here we present data that the S100A8/A9 protein complex represents the exclusive arachidonic acid-binding proteins in human neutrophils. Binding and competition studies revealed evidence that (i) fatty acid binding was dependent on the calcium concentration; (ii) fatty acid binding was specific for the protein complex formed by S100A8 and S100A9, whereas the individual components were unable to bind fatty acids; (iii) exclusively polyunsaturated fatty acids were bound by S100A8/A9, whereas saturated (palmitic acid, stearic acid) and monounsaturated fatty acids (oleic acid) as well as arachidonic acid-derived eicosanoids (15-hydroxyeicosatetraenoic acid, prostaglandin E(2), thromboxane B(2), leukotriene B(4)) were poor competitors. Stimulation of neutrophil-like HL-60 cells with phorbol 12-myristate 13-acetate led to the secretion of S100A8/A9 protein complex, which carried the released arachidonic acid. When elevation of intracellular calcium level was induced by A23187, release of arachidonic acid occurred without secretion of S100A8/A9. In view of the unusual abundance in neutrophilic cytosol (approximately 40% of cytosolic protein) our findings assign an important role for S100A8/A9 as mediator between calcium signaling and arachidonic acid effects. Further investigations have to explore the exact function of the S100A8/A9-arachidonic acid complex both inside and outside of neutrophils.

Antigens, Differentiation↗
PubMed1999

Synergistic effects of the alkaloid sinomenine in combination with the immunosuppressive drugs tacrolimus and mycophenolic acid.

The alkaloid sinomenine extracted from the medicinal plant Sinomenium acutum is used in China for the treatment of various rheumatic diseases. It has immunomodulatory properties in a cardiac allograft transplantation model. Its antiproliferative effect on human mononuclear cells in combination with different immunosuppressive drugs was further analysed in vitro. Sinomenine dose-dependently attenuated thymidine incorporation, interleukin-2 synthesis, and cell cycle progression of activated T-lymphocytes. Cell proliferation was synergistically decreased by addition of sinomenine together with suboptimal concentrations of the established immunosuppressive drugs tacrolimus or mycophenolic acid, respectively.

Animals↗
PubMed1998

Substrate specificity of acyl-CoA:Lysophospholipid acyltransferase (LAT) from pig spleen.

The present investigation was undertaken to gain insights into the nature of both substrate binding sites of acyl-CoA:lysophospholipid acyltransferase (LAT) which could be potentially useful for the identification and purification of this specific acyltransferase. Therefore, we have investigated the specificity of LAT from crude membranes of pig spleen toward various 1-palmitoyl-glycerophospholipids and 1-acyl-glycerophosphocholines (1-acyl-GPC). The enzyme showed the highest specificity toward 1-acyl-GPC and was able to distinguish between the acyl-chain length of the 1-acyl group within the 1-acyl-GPC molecule. We found preferential reactivity in the order C10:0 < C12:0 << C14:0, C18:0, C16:0 < C18:1 of 1-acyl-GPC. Lysophosphatidic acid or 1-O-alkyl-GPC were only poor substrates for the enzyme. In competition studies we could show that palmitic acid, oleic acid, arachidonic acid, and palmitoyl-CoA competitively inhibited LAT activity, whereas the coenzyme A failed to inhibit LAT enzyme activity in a concentration-dependent manner. We concluded that the ligand acyl-CoA is bound via its acyl chain. The finding that palmitoyl-CoA was a poor substrate as well as an inhibitor was the basis for protein purification. When palmitoyl-CoA-agarose was used as matrix for affinity chromatography, LAT enzyme activity was bound and eluted by high salt concentrations yielding an estimated 10-fold purification of the solubilized LAT enzyme.

1-Acylglycerophosphocholine O-Acyltransferase↗
PubMed1998

Synthesis of an unsaturated fatty acid analogue (18-(4'-azido-2'-hydroxybenzoylamino)-oleic acid) and its interaction with lysophosphatidylcholine: acyl-CoA-O-acyltransferase.

Acylation/deacylation reactions represent a basic requirement of triglyceride as well as phospholipid metabolism, and maintenance of membrane lipid composition. In order to examine enzymes participating in these pathways, we synthesized 18-(4'-azido-2'-hydroxybenzoylamino)-oleic acid, an iodinable photoaffinity analogue of oleic acid as a new tool for analyzing enzymes, especially those binding unsaturated fatty acids or acyl-CoAs. For the synthesis of omega-amino-oleic acid, coupling two bifunctional Cg-components was used. The described synthesis scheme is also suited for the specific generation of other fatty acid analogues with distinct positions of the double bond. The functionality of 18-(4'-azido-2'-hydroxybenzoylamino)-oleic acid was investigated with the enzyme lysophosphatidylcholine:acyl-CoA-O-acyltransferase (LAT) [EC 2.3.1.23], an enzyme that shows high specificity towards (poly)unsaturated fatty acyl-CoAs. It could be shown that the photolabel, esterified with coenzyme A, acts in the dark as a reversible inhibitor of the enzyme activity, but photolysis of the label results in irreversible inactivation of LAT. This inactivation could be prevented by addition of the native substrate arachidonyl-CoA during photolysis. Several proteins could be specifically visualized using the iodinated analogue. The data indicate that this new photoaffinity label may have application to identify and characterize lipid biosynthetic enzymes using unsaturated fatty acids as well as acyl-CoA binding proteins and the active site of these proteins.

1-Acylglycerophosphocholine O-Acyltransferase↗
PubMed1997

The mitogen-induced lysophospholipid:acyl-CoA acyltransferase (LAT) expression in human T-lymphocytes is diminished by hydrocortisone.

One of the earliest changes observed in activated lymphocytes is the enhanced incorporation of unsaturated fatty acids into membrane phospholipids catalyzed by phospholipases and acyltransferases. This early membrane phospholipid remodeling has been shown to be independent from protein synthesis. We have investigated the oleic acid incorporation into phospholipids of activated T-lymphocytes within hours and present data that the sustained membrane phospholipid remodeling in activated T-lymphocytes was largely decreased by cycloheximide and actinomycin D treatment while neither protein synthesis inhibitor had an effect on the fatty acid incorporation into phospholipids in resting T-lymphocytes. Lisofylline, an inhibitor of lysophosphatidic acid:acyl-CoA acyltransferase, had no inhibitory activity, indicating that the membrane lipid remodeling was not due to fatty acid incorporation into de novo-synthesized phospholipids. The membrane phospholipid alteration induced by mitogens was also diminished by hydrocortisone (HC) in a concentration-dependent manner. The steroid hormone antagonist RU486 failed to reverse but potentiated this inhibitory activity of HC. HC did not affect the fatty acid uptake, and the decrease of fatty acid incorporation into phospholipids induced by HC was accompanied by an increase of fatty acid incorporation into triglycerides, indicating that the inhibitory activity of HC was specific for fatty acid incorporation into phospholipids catalyzed by lysophospholipidacyl-CoA acyltransferase (LAT). HC did not directly inhibit the LAT enzyme activity. From these data we conclude that LAT gene transcription is induced as an early event following T-cell activation. The inhibitory action of hydrocortisone may give new insights into the regulatory mechanisms involved in LAT expression.

1-Acylglycerophosphocholine O-Acyltransferase↗
PubMed1997

T cell antigen receptor dependent signalling in human lymphocytes: cholera toxin inhibits interleukin-2 receptor expression but not interleukin-2 synthesis by preventing activation of a protein kinase C isotype, PKC-alpha.

Activation and translocation of protein kinases C is a key event in the regulation of T lymphocyte activation, proliferation and function. Stimulation of human peripheral blood lymphocytes with the monoclonal antibody BMA 031 raised against the T cell antigen receptor led to a bimodal activation of protein kinases C. The immediate activation and translocation of the protein kinase C isoform PKC-alpha was followed by activation and translocation of the protein kinase C-beta isoenzyme after 90 min of stimulation. Pretreatment of the cells with cholera toxin for 90 min completely abolished activation of protein kinase C-alpha. In sharp contrast, activation and translocation of protein kinase C-beta was not influenced by the bacterial toxin, suggesting that activation and translocation of different protein kinase C isoenzymes are regulated by distinct mechanisms of transmembrane signalling coupled to the T cell antigen receptor/CD3 complex. The expression of high affinity IL-2 receptors was completely inhibited by cholera toxin, while IL-2 synthesis and secretion were not influenced in BMA 031-stimulated human lymphocytes. Extensive control experiments have shown that the effects of cholera toxin were not mediated by its B subunit, and were independent of elevation of intracellular cAMP concentration, suggesting that cholera toxin interfered with a signalling pathway leading to activation of protein kinase C-alpha, which could be responsible for the inhibition of IL-2 receptor expression. This hypothesis was substantiated by the finding that upon introduction of antibodies against protein kinase C-alpha, IL-2 receptor gene expression was completely suppressed. The results suggest, that protein kinase C-alpha might be the major protein kinase C isoenzyme of a signal transduction cascade regulating IL-2 receptor expression in stimulated human lymphocytes.

Antibodies↗
PubMed1997

Endothelin-1 potently stimulates chloride secretion and inhibits Na(+)-glucose absorption in human intestine in vitro.

1. Serosally added synthetic endothelin-1 (ET-1) increased short-circuit current (Isc) across isolated muscle-stripped human colonic mucosa in vitro. Bumetanide inhibited Isc responses, indicating that ET-1 stimulates electrogenic Cl- secretion. 2. In isolated human jejunal mucosa, ET-1 exhibited a concentration-dependent dual action. At low concentrations it induced rapid increases in Isc and these were inhibited by bumetanide. At a higher concentration (0.1 microM), ET-1 provoked a drastic and progressive decrease in Isc below the baseline value. 3. Pretreatment with phlorizin or omission of glucose from the Krebs-Ringer solution at the apical (luminal) side of the jejunal mucosa prevented the decreases in Isc evoked by ET-1, suggesting that the peptide inhibits the glucose-coupled electrogenic Na+ absorption. Indeed, flux experiments with D-[14C]glucose demonstrated that ET-1 decreases jejunal glucose absorption by approximately 80% within 30 min. 4. Electron microprobe analyses of cryosections of human jejunum showed that ET-1 (0.1 microM) evokes a significant decrease in intracellular Na+ concentrations of villus (not crypt) epithelial cells, suggesting that the peptide attenuates apical Na(+)-glucose entry by reducing the activity of the Na(+)-glucose cotransporter, SGLT1. 5. In the presence of tetrodotoxin (TTX), ET-1-induced Cl- secretion was significantly reduced, in both human jejunal and colonic mucosa. However, the inhibitory effect on jejunal Na(+)-glucose absorption was not affected by TTX. 6. ET-1 increases electrogenic Cl- secretion across human intestinal mucosa in vitro. This effect is mediated in part via the activation of enteric nerves. Responses of the human jejunal mucosa to high ET-1 concentrations exhibit a second component, namely the rapid inhibition of electrogenic Na(+)-glucose absorption, which might be mediated by an inhibition of the transport activity of SGLT1. This effect is independent from neuronal mediators. Our results suggest different cellular action sites for ET-1 in human small and large intestine.

Absorption↗
PubMed1996

Immunomodulatory effects of the alkaloid sinomenine in the high responder ACI-to-Lewis cardiac allograft model.

Extracts of the plant Sinomenium acutum have been used safely since ancient times in Chinese medicine for treatment of rheumatic diseases, and the purified alkaloid, sinomenine, was recently shown to have anti-inflammatory and antirheumatic effects. This study describes the effects of sinomenine in the high responder ACI-->Lewis cardiac transplant model in which allograft rejection occurred at 5 days posttransplant. Treatment with sinomenine (15-30 mg/kg/day i.p.) or a subtherapeutic dose of cyclosporine (CsA, 1.5 mg/kg/day, i.m.) prolonged allograft survival only marginally (mean survival of 5.4 and 7.8 days, respectively). In contrast, the combination of sinomenine and CsA had a statistically significant synergistic effect, with a mean survival of 42.2 days (P < 0.001). Allografts harvested at day 5 from recipients treated with either sinomenine or CsA showed dense mononuclear cell infiltrates with widespread subepicardial infarcts, edema, and microvascular platelet and fibrin deposition. Immunohistologic analysis showed that intragraft leukocytes consisted of >75% macrophages with approximately 10-20% T cells and <5% B or NK cells. Mononuclear cell activation was shown by expression of IL-2R (CD25, 10-20%) and labeling for IL-2 (approximately 10%), and IFN-gamma (10-20%), as well as TNF-alpha (>50%) and iNOS (>50%), but only low levels of IL-4 or IL-10 (<5%). Intragraft endothelial cells were activated, as shown by upregulation of MHC class II antigen and ICAM-1 (CD54) compared with only basal levels in normal donors hearts. Combined sinomenine/CsA therapy significantly enhanced graft morphology, resulting in only mild mononuclear cell infiltration, and an absence of infarcts, platelets, or fibrin deposition. Though residual intragraft mononuclear cells at day 5, as in control grafts, consisted primarily of macrophages plus small numbers of IL-2R+ T cells, these cells lacked expression of IL-2, had only low levels of IFN-gamma, but showed dense labeling for IL-4 and IL-10. In addition, TNF-alpha and iNOS were reduced to basal levels and no endothelial cell activation was observed, despite high titers of endothelium-bound IgM, IgG, and C3. Mitogen-induced in vitro proliferation of rat thymocytes was also more effectively decreased by the sinomenine/CsA combination than by either agent alone. These studies demonstrate the therapeutic value of sinomenine in transplantation, and indicate that this agent has novel and interesting antimacrophage, T cell, and endothelial effects that warrant further evaluation.

Adjuvants, Immunologic↗
PubMed1996

Identification of two different lysophosphatidylcholine:acyl-CoA acyltransferases (LAT) in pig spleen with putative distinct topological localization.

The lysophosphatidylcholine:acyl-CoA acyltransferase (LAT, EC 2.3.1.23) is an integral membrane protein participating in the membrane turnover and the T-cell activation process. Here, we present data that crude membranes of pig spleen contain two different LAT enzyme activities based on topological localization studies and the enzyme specificities towards various acyl-CoAs. When crude membranes are washed with solutions of high ionic strength the supernatant contains a distinct LAT activity that we refer to as peripheral LAT (pLAT). The majority of LAT activity is found in the membrane pellet also after treatment with CHAPS. The CHAPS-insoluble LAT activity is named integral LAT (iLAT) accordingly. While pLAT prefers arachidonoyl-CoA rather than oleoyl-CoA, iLAT shows no specificity towards both unsaturated acyl-CoAs. Further investigations reveal that the CHAPS-insoluble LAT activity in the membranes can be solubilized by n-octyl glucoside and restored to original activity by reconstitution with artificial membranes. The reconstituted iLAT prefers arachidonoyl-CoA rather than oleoyl-CoA. Despite a great deal of effort by several groups little progress has been made so far in LAT purification because of the enzyme instability. We establish experimental conditions that enhance the stability of both enzyme activities and, therefore, allow further protein purification.

1-Acylglycerophosphocholine O-Acyltransferase↗
PubMed1996

Amelioration of rat experimental arthritides by treatment with the alkaloid sinomenine.

The effects of treatment with sinomenine, a pure alkaloid extracted from the chinese medical plant Sinomenium acutum, were investigated in rat adjuvant arthritis (AA) and antigen-induced arthritis (AIA). In AA, long-term, intraperitoneal (i.p.) treatment induced significant improvement of arthritic score, hind paw swelling, body weight and erythrocyte sedimentation rate (ESR) beginning past the clinical peak of the disease. In-acute AIA, short and middle-term treatment with sinomenine around and following induction of arthritis induced a dose-dependent decrease of both joint swelling and ESR, starting after the peak of arthritis, and a significant reduction of joint destruction on day 3. There was no rebound of the arthritic signs following suspension of treatment. Long-term treatment of chronic AIA partially ameliorated clinical parameters and significantly counteracted joint destruction. Maximal plasma concentrations of 22.5 micrograms/ml, fast wash out (half-life 4.24 +/- 0.99 h; mean +/- S.E.M.) and no evidence of accumulation of sinomenine were observed following single or repeated i.p. injection of 150 mg/kg. In vitro, sinomenine markedly inhibited proliferation of synovial fibroblasts from AIA or normal rats, both at rest and following activation with either transforming growth factor beta 2 (TGF-beta 2) or interleukin-1 beta (IL-1 beta). The effect was dose-dependent and half-maximal inhibition of proliferation occurred at 20.6 micrograms/ml, that is, within the in vivo therapeutic range of the drug. Late therapeutic effects of sinomenine in rat arthritic models despite early start of treatment may be related to its antiproliferative effects on synovial fibroblasts in addition to its previously reported anti-inflammatory properties.

Adjuvants, Immunologic↗
PubMed1995

GCAP-II: isolation and characterization of the circulating form of human uroguanylin.

The systematic isolation of circulating regulatory peptides which generate cGMP as second messenger resulted in the identification of a novel member of the guanylin family. In the present study we describe the purification and amino acid sequence of a new guanylate cyclase C activating peptide (GCAP-II). GCAP-II contains 24 amino acids in the following sequence: FKTLRTIANDDCELCVNVACTGCL. Its molecular mass is 2597.7 Da. The 16 C-terminal amino acids are identical to uroguanylin from human urine. native and synthetic GCAP-II activate GC-C, the specific guanylate cyclase receptor, of cultured human colon carcinoma (T84) cells. GCAP-II stimulates chloride secretion in isolated human intestinal mucosa mediated by intracellular cGMP increase. GCAP-II specific antibodies were used to localize the peptide by immunohistochemistry in entero-endocrine cells of the colonic mucosa.

Amino Acid Sequence↗
PubMed1995

Impaired endotoxin-induced interleukin-1 beta secretion, not total production, of mononuclear cells from ESRD patients.

Lipopolysaccharide (LPS)-induced interleukin-1 beta (IL-1 beta) and tumor necrosis factor alpha (TNF alpha) production and secretion from peripheral blood mononuclear cells (PBMC) were determined in a longitudinal study with repeated measurements in PBMC from patients with chronic uremia not on hemodialysis (N = 8), end-stage renal disease (ESRD) patients (N = 8), and healthy controls (N = 7). ESRD patients were studied while using low-flux Cuprophan dialyzers and again using high-flux AN 69 dialyzers. Total (cell-associated plus secreted) LPS-induced IL-1 beta production was enhanced in uremic patients, but similar to controls in ESRD patients on Cuprophan. In contrast, LPS-induced IL-1 beta secretion (secreted amounts in % of total production) was similar to controls in uremic patients, but significantly reduced in ESRD patients on Cuprophan (P < 0.01). During AN 69 hemodialysis, LPS-induced total IL-1 beta production remained unchanged but IL-1 beta secretion increased significantly (P < 0.05) compared to Cuprophan dialysis. Increased IL-1 beta secretion coincided with a suppression in PGE2 synthesis (P < 0.02). Similarly, blockade of endogenous PGE2 by indomethacin increased LPS-induced IL-1 beta secretion (P < 0.01) but did not enhance total IL-1 beta production in PBMC from controls and patients on Cuprophan hemodialysis. Neither total production nor secretion of TNF alpha was different comparing the three study groups. We conclude that LPS-induced IL-1 beta secretion, but not total production, is impaired in PBMC from ESRD patients on long-term Cuprophan hemodialysis. This functional change in the PBMC response is specific for IL-1 beta, not due to uremia per se but hemodialysis-dependent and reversible. Hemodialysis with AN 69 suppresses endogenous PGE2 synthesis in PBMC which is associated with increased LPS-induced IL-1 beta secretion in the presence of unchanged total IL-1 beta production. We speculate that PGE2 could inactivate the IL-1 beta converting enzyme which is essential for processing and secretion of mature IL-1 beta.

Adult↗