Marien W.J.A. Fieren

Endotoxin‐stimulated peritoneal macrophages obtained from continuous ambulatory peritoneal dialysis patients show an increased capacity to release interleukin‐1βin vitro during infectious peritonitis

Abstract. Interleukin‐1 (IL‐1) release by peritoneal macrophages obtained from patients on continuous ambulatory peritoneal dialysis (CAPD) was studied in nine patients during an infection‐free period and eight patients during an infectious peritonitis, using an ELISA for IL‐ 1β. Without exogenous stimulation with LPS, peritoneal macrophages from infected and unin‐fected patients released the same amounts of IL‐lβ, 183pM40 pg ml‐1 24 h‐1) per 106 cells (means + SEM) and 251 pM 6 pg ml‐1, respectively. However, in response to a dose of 5 μg ml‐1 of LPS, peritoneal macrophages released significantly more (P < 0.005) IL‐1β during peritonitis (6579 β 2793 pg ml‐1 24 h‐1 per 106 cells) compared with the infection‐free period (1040 pM 182 pg ml‐1). These findings show that after microbial invasion of the peritoneal cavity, peritoneal macrophages are primed in vivo to release an increased amount of IL‐lβin vitro after subsequent exogenous stimulation with LPS, indicating that peritoneal mac‐rophage activation for IL‐1β secretion occurs in steps.,

Prostaglandin E2 inhibits the release of tumor necrosis factor-α, rather than interleukin 1β, from human macrophages

Abstract We have reported previously that macrophages obtained from renal patients on continuous ambulatory peritoneal dialysis (CAPD) during an episode of infectious peritonitis display a decrease in intracellular cAMP levels and in spontaneous in vitro release of PGE 2 and PGI 2 . Such macrophages also release large quantities of IL-1β and TNFα when stimulated in vitro by LPS. In view of the interregulatory effects between PGE 2 and macrophage cytokines (IL-1β and TNFα) in their production, we examined in the present work to what extent the LPS-induced release of either IL-1β or TNFα in vitro from CAPD-originated peritoneal macrophages is affected by graded doses of exogenous PGE 2 (range 0 – 1000 ng/ml) and by the cyclooxygenase inhibitor indomethacin (INDO) (10 −6 M). IL-1β and TNFα were determined using an enzyme-linked immunoabsorbent assay and an immunoradiometric assay, respectively. We found that PGE 2 invariably induced a dose-dependent decrease in TNFα release. In peritoneal macrophages collected during an infection-free period, TNFα release decreased from 3225 pg/ml (controls) to 353 pg/ml at 1000 ng/ml of PGE 2 , and in peritoneal macrophages collected during an episode of infectious peritonitis, it decreased from 4100 pg/ml (controls) to 545 pg/ml at 100 ng/ml of PGE 2 . However, PGE 2 failed to influence the secretion of IL-1β. INDO induced an approx, two-fold increase in TNFα release, but had no effect on IL-1β release. These findings indicate that exogenous and endogenous PGE 2 controls the release of TNFα rather than IL-1β from LPS-stimulated peritoneal macrophages.

Mechanisms Regulating Cytokine Release from Peritoneal Macrophages during Continuous Ambulatory Peritoneal Dialysis

The proinflammatory cytokines interleukin-1 (IL-1 beta) and tumor necrosis factor-alpha (TNF alpha) are key mediators of the bodys response to infection. Peritoneal macrophages from continuous ambulatory peritoneal dialysis (CAPD) patients isolated during peritonitis have an increased capacity to secrete IL-1 beta and TNF alpha. This peritoneal macrophage activation for IL-1 beta and TNF alpha release is a two-stage process. In contrast, peritonitis macrophages and infection-free macrophages stimulated in vitro with bacteria generate a decreased amount of the anti-inflammatory prostanoids. Exogenous and endogenous prostaglandin E2 (PGE2) was found to inhibit the release of TNF alpha rather than IL-1 beta from peritoneal macrophages, indicating that the synthesis and secretion of these cytokines is distinctly regulated by PGE2. In addition to macrophage products, acting in an autocrine fashion cytokine production and release may be regulated by secretory products of other cells in the peritoneal cavity including lymphocytes and mesothelial cells, which have the capability to produce various mediators. No evidence was found that the NO system is an important part of the antimicrobial arsenal of peritoneal macrophages.

Tumour necrosis factor in inflammation: relation to other mediators and to macrophage antitumour defence

Early reports on spontaneous regression of certain human tumours during bacterial infections soon led to the use of bacteria-free filtrates from cultures of Grampositive and Gram-negative bacteria in the therapy of human neoplasia (for reference see [1]) . These filtrates, named Coleys toxin after the surgeon who developed them, when given to several cancer patients nearly 100 years ago, resulted in necrotic tumour regression. It was also mentioned that the filtrates were quite toxic to recipients . Subsequent attempts to separate the therapeutic from the toxic component led ultimately to the isolation of bacterial cell wall lipopolysaccharide (LPS, synonym for endotoxin) . The occurrence of a cytotoxic factor in the serum of mice which had undergone treatment with LPS [2], prompted Carswell et al ., who confirmed the observation, to coin the term tumour necrosis factor (TNF), a name which has been in use now for 15 years [3] . Carswell et al . also suggested that TNF was produced by activated macrophages in response to LPS. In retrospect, it is almost certain that some of Coleys toxins contained LPS. Accordingly, both the beneficial and the concomitant adverse actions were conceivably mediated by TNF (see [4] and [5]) . The name tumour necrosis factor covers two distinct substances, TNFa and TNFs [4] . TNFa is the monocyte/macrophage-derived protein, whereas TNFs is the cytotoxic glycoprotein produced mainly by lymphocytes . Cloning of the genes responsible for the production of these factors and their expression in Escherichia coli, has allowed the preparation of large amounts and their biochemical

Continuous ambulatory peritoneal dialysis: pharmacokinetics and clinical outcome of paclitaxel and carboplatin treatment

PurposeAdministration of chemotherapy in patients with renal failure, treated with hemodialysis or continuous ambulatory peritoneal dialysis (CAPD) is still a challenge and literature data is scarce. Here we present a case study of a patient on CAPD, treated with weekly and three-weekly paclitaxel/carboplatin for recurrent ovarian cancer.ExperimentalDuring the first, second and ninth cycle of treatment, blood, urine and CAPD samples were collected for pharmacokinetic analysis of paclitaxel and total and unbound carboplatin-derived platinum.ResultsTreatment was well tolerated by the patient. No excessive toxicity was observed and at the end of treatment she was in a complete remission. The plasma pharmacokinetics of paclitaxel were unaltered compared to historical data, with neglectable urinary and CAPD clearance. In contrast, the pharmacokinetics of carboplatin were altered, with doubled half-lives compared to patients with normal renal function. Of the administered carboplatin dose, up to 20% was cleared via the dialysate, while only up to 8% was cleared via the urine.ConclusionPaclitaxel and carboplatin can be safely administered to patients with chronic renal failure on CAPD. For paclitaxel the generally applied dose can be administered, and although for carboplatin dose-adjustment is required due to the diminished renal function, the dose can be calculated using Calvert’s formula.

Peritoneal macrophages from patients on continuous ambulatory peritoneal dialysis show a differential secretion of prostanoids and interleukin-1β

In vitro secretion of the prostanoids PGE2 and PGI2 and of the cytokine IL-1 beta by peritoneal macrophages obtained from CAPD patients during episodes of peritonitis and infection free periods, was determined, after culturing with or without 5 micrograms/ml of LPS. The release of PGE2 and PGI2 as measured by its stable metabolite 6-keto-PGF alpha was determined in 10 episodes of peritonitis and 10 infection free periods. IL-1 beta release was determined in 14 episodes of peritonitis and 20 infection free periods. PGI2 release from macrophages declined sharply during peritonitis both in the absence and presence of LPS in the culture medium (p less than 0.005). A tendency to decreased PGE2 release was found during peritonitis, when macrophages were cultured in the absence of LPS. In the presence of LPS, the same amounts of PGE2 were released during peritonitis and during an infection free period. On the other hand, peritoneal macrophages released significantly more IL-1 beta during peritonitis as compared to an infection free period, provided that the cells were in vitro stimulated with LPS. In view of the interregulatory effects between prostanoids and macrophage cytokines in their production, these findings may indicate that the impaired release of PGI2 during peritonitis has allowed the macrophages to secrete more IL-1 beta after in vitro stimulation with LPS. This implies that PGI2 and PGE2 may play a distinct role in the regulation of cytokine secretion by these cells.

Cloudy Peritoneal Dialysate: In Search of a Clear Cause?

Peritoneal dialysis–associated peritonitis is usually caused by infection. It is characterized by abdominal pain and cloudy peritoneal effluent caused by an increased peritoneal leukocyte count (>100 million cells/L, more than 50% of which are neutrophils), as well as positive effluent

Increasedin vitro release of interleukin-1 by LPS stimulated peritoneal macrophages obtained from patients on continuous ambulatory peritoneal dialysis (CAPD) during an infectious peritonitis

Peritoneal macrophages, collected from dialysate of patients treated with Continuous Ambulatory Peritoneal Dialysis (CAPD) because of end stage renal failure, produce in vitro various mediators such as cyclooxygenase products which in turn stimulates the production of the second messenger cyclic AMP (cAMP), These substances may have inhibitory effects on several functions of mononuclear phagocytes. Earlier we found that when CAPD is complicated by an episode of infectious peritonitis, peritoneal macrophages show a marked decrease in the spontaneous in vitro secretion of cyclooxygenase products as well as in the intracellular cAMP levels in comparison with an infection free period [1]. We postulated that the diminished production of these substances with down regulatory properties would permit the macrophages to release a higher amount of the pro-inflammatory polypeptide interleukin-1 (IL-I) during peritonitis [2]. This mediator plays, together with related cytokines, a key role in the regulation of (acute) inflammatory processes. In the present study we aimed to examine the release of IL-1//, the main secretory form of IL-1, by peritoneal macrophages of CAPD patients, especially with the intention to analyse whether peritoneal macrophages secrete higher amounts of IL-I/~, when CAPD is complicated by an episode of peritonitis. Patients and methods