Management of encapsulating peritoneal sclerosis: a guideline on optimal and uniform treatment.

Encapsulating peritoneal sclerosis (EPS) represents a rare complication of long-term peritoneal dialysis (PD). It is characterised by diffuse peritoneal membrane fibrosis, progressive intestinal encapsulation and the clinical spectrum of intestinal obstruction. The pathogenesis is as yet not well understood but includes inflammation, angiogenesis and fibrosis. The current diagnosis of EPS lacks specificity and relies on clinical, radiographic or macroscopic evaluation. There is no general agreement on managing EPS although accumulating clinical data suggest drug treatment (steroids, tamoxifen), surgery (enterolysis) or a combination of both. Here, we provide a short overview on the current knowledge of EPS, with a focus on treatment. Moreover, we present a diagnostic and a therapeutic algorithm for EPS based on the best available published data and our combined experience.

Albumin and whole-body protein synthesis respond differently to intraperitoneal and oral amino acids.

Patients with peritoneal dialysis are at risk for malnutrition and hypoalbuminemia, which are indicators of poor outcome. Recently, it was shown that dialysis solutions containing amino acids (AAs) and glucose improve protein anabolism in peritoneal dialysis patients. We determined if the same solutions could increase the fractional synthesis rate of albumin along with whole-body protein synthesis. Changes in the fractional albumin synthetic rate reflect acute change in hepatic albumin synthesis. A random-order cross-over study compared the effects of Nutrineal (AA source) plus Physioneal (glucose) dialysate with Physioneal alone dialysate. Eight patients in the overnight fasting state were compared to 12 patients in the daytime-fed state. Fractional albumin synthetic rate and whole-body protein synthesis were determined simultaneously using a primed-continuous infusion of L-[1-(13)C]-leucine. Fractional albumin synthesis on AAs plus glucose dialysis did not differ significantly from that on glucose alone in the fasting or the fed state. Protein intake by itself (fed versus fasting) failed to induce a significant increase in the fractional synthetic rate of albumin. Conversely, the oral protein brought about a significant stimulation of whole-body protein synthesis. Our findings show that the supply of AAs has different effects on whole-body protein synthesis and the fractional synthetic rate of albumin.

Peritoneal protein losses and cytokine generation in automated peritoneal dialysis with combined amino acids and glucose solutions.

OBJECTIVES: Protein-energy malnutrition as a consequence of deficient protein intake frequently occurs in peritoneal dialysis (PD) patients. Previously, we showed that peritoneal dialysate containing a mixture of amino acids (AA) and glucose has anabolic effects. However AA-dialysate has been reported to increase intraperitoneal protein and AA losses and the release of proinflammatory cytokines (interleukine-6 (IL-6) and tumor necrosis factor alpha (TNFalpha)). We investigated the effect of AA plus glucose (AAG) solutions on peritoneal protein losses and cytokine generation. METHODS: In 6 patients on standard automated peritoneal dialysis (APD) 12 APD sessions of 6 cycles each were performed during the night using dialysate containing 1.1% AA plus glucose or glucose alone as control. Protein losses and TNFalpha and IL-6 concentrations were measured in dialysates separately collected from nightly cycling and daytime dwell. RESULTS: The 24 hour-protein losses with AAG (median 6.7 g, range 4.7-9.4 g) were similar to control dialysate (median 6.0 g, range 4.2-9.2 g). Daytime dialysate IL-6 levels were higher after nightly AAG dialysis than after control dialysis (142 pg/ml and 82 pg/ml, respectively, P<.05). TNFalpha concentrations were very low. CONCLUSION: Nightly APD with amino acids containing dialysate was associated with an increase in peritoneal IL-6 generation during the day. The addition of AA to standard glucose dialysis solutions did not induce a significant increase of peritoneal protein losses.

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 body's 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.

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

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.

Prostaglandin E2 inhibits the release of tumor necrosis factor-alpha, rather than interleukin 1 beta, from human macrophages.

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 PGE2 and PGI2. Such macrophages also release large quantities of IL-1 beta and TNF alpha when stimulated in vitro by LPS. In view of the interregulatory effects between PGE2 and macrophage cytokines (IL-1 beta and TNF alpha) in their production, we examined in the present work to what extent the LPS-induced release of either IL-1 beta or TNF alpha in vitro from CAPD-originated peritoneal macrophages is affected by graded doses of exogenous PGE2 (range 0-1000 ng/ml) and by the cyclooxygenase inhibitor indomethacin (INDO) (10(-6) M). IL-1 beta and TNF alpha were determined using an enzyme-linked immunoabsorbent assay and an immunoradiometric assay, respectively. We found that PGE2 invariably induced a dose-dependent decrease in TNF alpha release. In peritoneal macrophages collected during an infection-free period, TNF alpha release decreased from 3225 pg/ml (controls) to 353 pg/ml at 1000 ng/ml of PGE2, 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 PGE2. However, PGE2 failed to influence the secretion of IL-1 beta. INDO induced an approx. two-fold increase in TNF alpha release, but had no effect on IL-1 beta release. These findings indicate that exogenous and endogenous PGE2 controls the release of TNF alpha rather than IL-1 beta from LPS-stimulated peritoneal macrophages.

[A patient with a wide aorta and 2 wide kidney pelves: retroperitoneal fibrosis]. / Een patiënt met een wijde aorta en twee wijde nierbekkens: retroperitoneale fibrose.

The case is discussed of a patient with renal insufficiency due to severe stenosis of both ureters brought about by a periaortic inflammatory process. Such periaortitis is seen in severe atherosclerosis; the condition allegedly occurs in 5 to 23% of all patients with an abdominal aortic aneurysm. The literature on this form of retroperitoneal fibrosis is reviewed.

Peritoneal macrophages from patients on continuous ambulatory peritoneal dialysis have an increased capability to release tumour necrosis factor during peritonitis.

We have reported previously that human peritoneal macrophages collected from patients on Continuous Ambulatory Peritoneal Dialysis (CAPD) during an episode of peritonitis secrete increased amounts of interleukin-1 (IL-1), as compared to those collected during an infection free period, provided the cells were stimulated in vitro by LPS. We now report that such macrophages release also higher amounts of Tumor Necrosis Factor (TNF), if collected during peritonitis and stimulated subsequently in vitro by LPS. The increase in release of TNF was ascertained by radio-immunoassays as well as by bioassay of cytostatic effect against the highly sensitive TNF target-cell line L929 murine transformed fibroblasts. The present reported results, in addition to previously reported data on release of IL-1, indicate that induction of release of cytokines from human peritoneal macrophages is a dual stepwise process: first priming in vivo in an inflammatory environment and, secondly stimulation in vitro by LPS.

Endotoxin-stimulated peritoneal macrophages obtained from continuous ambulatory peritoneal dialysis patients show an increased capacity to release interleukin-1 beta in vitro during infectious peritonitis.

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-1 beta. Without exogenous stimulation with LPS, peritoneal macrophages from infected and uninfected patients released the same amounts of IL-1 beta, 183 +/- 40 pg ml-1 24 h-1) per 10(6) cells (means +/- SEM) and 251 +/- 96 pg ml-1, respectively. However, in response to a dose of 5 micrograms ml-1 of LPS, peritoneal macrophages released significantly more (P less than 0.005) IL-1 beta during peritonitis (6579 +/- 2793 pg ml-1 24 h-1 per 10(6) cells) compared with the infection-free period (1040 +/- 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-1 beta in vitro after subsequent exogenous stimulation with LPS, indicating that peritoneal macrophage activation for IL-1 beta secretion occurs in steps.

Peritoneal macrophages from patients on CAPD show an increased capacity to secrete interleukin-1 beta during peritonitis.

The in vitro release of interleukin-1 beta (IL-1 beta) by peritoneal macrophages from CAPD patients was studied during 16 infection free periods (16 patients) and 13 episodes of peritonitis (10 patients) using an ELISA. Without exogeneous stimulation with LPS, peritoneal macrophages released the same amounts of IL-1 beta. irrespective if they were obtained during an infection free period (473 +/- 92 pg/ml 24h, means +/- SEM) or during peritonitis (324 +/- 125 pg/ml). However, in response to a dose of 5 micrograms/ml of LPS, peritoneal macrophages released significantly more (p less than 0.005) IL-1 beta during peritonitis (6155 +/- 1743 pg/ml). These findings show that during peritonitis, peritoneal macrophages are primed in vivo to release more IL-1 beta in vitro after stimulation with LPS, indicating that activation of peritoneal macrophages for IL-1 beta secretion occurs stepwise.

Infectious-inflammatory changes in cyclic AMP levels and in their regulation by prostaglandins in human peritoneal macrophages.

Peritoneal macrophages of renal patients on continuous ambulatory peritoneal dialysis (CAPD) have been collected when CAPD was without complications, during an intercurrent infectious peritoneal inflammation and after recovery. Levels of cyclic AMP, release of cyclo-oxygenase metabolites, and responsiveness, in terms of cyclic AMP elevation, to either PGE2 or to DC-PGI2 (a stable analogue of PGI2) were examined. Peritoneal inflammation was associated with a sharp drop in cyclic AMP, which was restored after recovery. Production of TXA2, PGI2 and PGE2 parallelled the direction of changes in cyclic AMP levels, except, that release of PGE2 entirely failed to recover. Macrophages during the uncomplicated stage of CAPD proved more responsive to DC-PGI2 than to PGE2. During inflammation the cells displayed a marked increase in sensitivity towards PG stimulation. Improved sensitivity was more pronounced with PGE2 than with DC-PGI2 and so the original difference between responsiveness of the cells to the PGs was abolished. Several findings are compatible with the view that endogenous PGI2 governs the cyclic AMP levels in human non-inflammatory peritoneal macrophages. However, during infectious-inflammation the cells undergo changes which render a reduced production of PGI2 insufficient to explain the drop in cyclic AMP.

Cyclic AMP levels and their regulation by prostaglandins in peritoneal macrophages of rats and humans.

Basal levels of cyclic AMP and their alterations following stimulation by prostaglandins have been examined in rat peritoneal macrophages and in such cells of humans with renal disease on continuous ambulatory peritoneal dialysis (CAPD). Resident cells of rats contained more cyclic AMP than elicited macrophages, but the responsiveness to either PGE2 or DC-PGI2 (a stable synthetic analogue of PGI2) was higher with elicited than with resident cells. However, both kinds of peritoneal macrophages of rats were, in terms of cyclic AMP elevation, more sensitive to stimulation by PGE2 than by DC-PGI2. The CAPD macrophages of humans were elicited cells. The unstimulated levels of cyclic AMP in these human macrophages were much higher than those in elicited rat cells. Furthermore the human macrophages proved more sensitive to stimulation by DC-PGI2 than by PGE2. The reversed sensitivity, in comparison with rat cells, reflects the utterly poor effects of PGE2 in the human macrophages. The distinction in responsiveness to PGE2 and DC-PGI2 of the rat macrophages is compatible with the earlier reported distribution of and affinity to receptor binding sites of these PGs in the rat cells. The findings with the human macrophages suggest, however, that in these cells either the distribution of specific binding sites or the affinity of the two PGs to such sites might be substantially different from that of rats.