Peritoneal dialysis fluid induces change of mononuclear phagocyte proportions

The Effect of Advanced Glycation End-Products and Aminoguanidine on Tnfα Production by Rat Peritoneal Macrophages

Objective

To evaluate the effect of advanced glycation end-products (AGEs) and the inhibitor of their formation, aminoguanidine, on tumor necrosis factor-α (TNFα) production (as a functional marker) by rat peritoneal macrophages (PMΦ).

Design

Charles River rats underwent a daily intraperitoneal injection of peritoneal dialysis solution [(PDS), 4.25 g/dL dextrose; Dialine, Travenol, Ashdod, Israel] for a 2-month period (group E). Another group of rats was subjected to the same protocol with the addition of 25 mg/kg aminoguanidine (group A). Three control groups were utilized: ( 1 ) rats that were injected daily with aminoguanidine only (group AO), ( 2 ) rats that were injected with Dulbecco's phosphate-buffered saline (group D), and ( 3 ) rats in which no intervention was carried out (group C). After 2 months, PMΦ were isolated from rat peritoneal effluent and their TNFα production measured by ELISA in cell-free culture supernatants, in both the basal state and after 24-hour stimulation with lipopolysaccharide (LPS). The concentrations of AGEs in peritoneal effluent were assayed and correlated to TNFα levels. PMΦ obtained from normal rats were then incubated for 24 hours with ( 1 ) the peritoneal effluent of each of the above respective groups, with or without LPS; ( 2 ) increasing concentrations of AGEs (0 - 250 μg/mL); and ( 3 ) increasing concentrations of aminoguanidine (0 - 7.5 mg/mL), and TNFα secretion again determined.

Results

After 2 months of daily intraperitoneal injection of PDS, in the basal state, TNFα production was significantly higher in PMΦ isolated from the peritoneal effluent groups (groups E, A, and AO) compared to controls (group C). Following LPS stimulation, a further increase in TNFα secretion was seen, with a significantly greater response in group AO versus groups E, A, and D. Effluent AGEs were markedly elevated only in group E. No correlation was found between TNFα secretion by these PMΦ and the concentration of AGEs. On incubation with the respective peritoneal effluents (groups E, A, and AO), in both the basal and stimulated state, TNFα production by PMΦ from normal rats was significantly enhanced compared to group C. Incubation with increasing concentrations of AGEs or aminoguanidine resulted in an increase of TNFα secretion by these PMΦ.

Conclusions

Following intermittent intraperitoneal administration of glucose-based PDS, rat PMΦ are chronically activated, as evidenced by increased basal TNFα secretion. The peritoneal effluent of such treated animals is capable of stimulating TNFα production by normal rat PMΦ. These data suggest that glucose-based PDS acts as a primer of PMΦ, which retain their ability to further stimulation by LPS. Although, in vitro, AGEs promote TNFα secretion by normal rat PMΦ, in vivo, their influence is probably modulated by other factors. Aminoguanidine has a specific inducing effect on rat PMΦ, independent of glucose-based PDS.

Host Defense Mechanisms in the Peritoneal Cavity of Continuous Ambulatory Peritoneal Dialysis Patients: First of Two Parts

This article provides a review of studies on peritoneal white blood cells (WBC) in CAPD patients. To some extent these studies support the concept that the peritoneal cavity of these patients contains adequate-functioning WBC that can provide effective antimicrobial defenses when they are studied in dialysate-free media. Commercially available dialysis solutions significantly impair WBC function. In some patients with high incidences of peritonitis, there appears to be reduced bactericidal capacity of their peritoneal macrophages. CAPD seems to contribute to a state of both macrophage and lymphocyte activation in the peritoneal cavity. The clinical consequences of this chronic activation are not known.

Experimental Peritoneal Dialysis Solutions

A survey of the literature suggests continued interest in modifying the composition of peritoneal dialysis solutions. Osmotic agents such as glucose polymers and short-chain polypeptides may find a role in peritoneal dialysis fluids as partial substitutes for dextrose. New solutions containing amino acids should serve as more than sinks for uremic toxins by providing nutritional support and by ameliorating uremic lipid abnormalities. Increasing emphasis is being paid to biocompatibility during the development of new peritoneal dialysis fluids.

Effect of Different Buffers on the Biocompatibility of Capd Solutions

Commercially available solutions for continuous ambulatory peritoneal dialysis (CAPO) affect the viability and function of the cells in the peritoneal cavity. The low biocompatibility of the solutions may be caused by a low pH, hyperosmolality, high glucose content, and lack of potassium, glutamine, and other components essential for normal cellular functions. The nature of the buffer employed is also important for the cytotoxicity of the solutions. Lactate, the most frequently used buffer, has been shown to inhibit cellular functions important for the peritoneal defense system including phagocytosis, bacterial killing, and secretion of cytokines. It is generally believed that the cytotoxicity of lactate is caused by lowering of intracellular pH and impairment of metabolism due to changed redox potentials. However, the cytotoxicity of lactate is highly dependent upon the pH of the solutions, indicating that passive or active diffusion across the cell membrane is determining the effects of lactate. Bicarbonate has been heavily advocated as an alternative buffer because it is the most important naturally occurring buffer in plasma and it enables a pH of approximately 7.4 in the solutions. However, due to sedimentation of calcium carbonate (CaCO3) and production of toxic glucose metabolites it is difficult to prepare and store bicarbonate-based solutions. Moreover, investigations have revealed that even bicarbonate-based solutions are not optimal regarding biocompatibility, presumably due to a paradoxical intracellular acidification caused by influx of carbon dioxide (CO2). More recently, the effect of other buffers such as pyruvate and histidine have been examined. Especially pyruvate is a promising new buffer candidate.

Conventional CAPD solutions based on lactate have been shown to impair a wide variety of cell functions important for the peritoneal host defense. Apart from the influence of hyperosmolality, high glucose concentration, lack of potassium, glutamine, and other factors, this seems to be due to the combination of low pH and high lactate concentration. Presumably, lactate carries protons across the membrane, which results in intracellular acidification and increased intracellular lactate concentration, both of which may impair cell metabolism and function.

Bicarbonate-based solutions are less toxic than lactate-based solutions -primarily attributable to the higher pH. However, experiments performed by our group have indicated that bicarbonate concentrations that are too high may also affect cell function, and that a solution containing both bicarbonate and lactate may be superior. However, further studies are needed to fully elucidate this problem.

Pyruvate seems to be a promising new buffer candidate with lower toxicity than lactate solutions at identical pH and glucose content. Comparison of pyruvate, lactate, and bicarbonate solutions regarding cytotoxicity and especially intracellular acidification will hopefully shed new light on the toxic properties of these solutions.

Inflammatory macrophages switch to CCL17-expressing phenotype and promote peritoneal fibrosis

Peritoneal fibrosis remains a problem in kidney failure patients treated with peritoneal dialysis. Severe peritoneal fibrosis with encapsulation or encapsulating peritoneal sclerosis is devastating and life-threatening. Although submesothelial fibroblasts as the major precursor of scar-producing myofibroblasts in animal models and M2 macrophage (Mϕ)-derived chemokines in peritoneal effluents of patients before diagnosis of encapsulating peritoneal sclerosis have been identified, attenuation of peritoneal fibrosis is an unmet medical need partly because the mechanism for cross talk between Mϕs and fibroblasts remains unclear. We use a sodium hypochlorite-induced mouse model akin to clinical encapsulated peritoneal sclerosis to study how the peritoneal Mϕs activate fibroblasts and fibrosis. Sodium hypochlorite induces the disappearance of CD11b^high F4/80^high resident Mϕs but accumulation of CD11b^int F4/80^int inflammatory Mϕs (InfMϕs) through recruiting blood monocytes and activating local cell proliferation. InfMϕs switch to express chemokine (C-C motif) ligand 17 (CCL17), CCL22, and arginase-1 from day 2 after hypochlorite injury. More than 75% of InfMϕs undergo genetic recombination by Csf1r-driven Cre recombinase, providing the possibility to reduce myofibroblasts and fibrosis by diphtheria toxin-induced Mϕ ablation from day 2 after injury. Furthermore, administration of antibody against CCL17 can reduce Mϕs, myofibroblasts, fibrosis, and improve peritoneal function after injury. Mechanistically, CCL17 stimulates migration and collagen production of submesothelial fibroblasts in culture. By breeding mice that are induced to express red fluorescent protein in Mϕs and green fluorescence protein (GFP) in Col1a1-expressing cells, we confirmed that Mϕs do not produce collagen in peritoneum before and after injury. However, small numbers of fibrocytes are found in fibrotic peritoneum of chimeric mice with bone marrow from Col1a1-GFP reporter mice, but they do not contribute to myofibroblasts. These data demonstrate that InfMϕs switch to pro-fibrotic phenotype and activate peritoneal fibroblasts through CCL17 after injury. CCL17 blockade in patients with peritoneal fibrosis may provide a novel therapy. © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Variations of Cytokine Levels and Production in CAPD Patients

Macrophages, predominant cells in dialysates of patients on CAPD without peritonitis, produce a wide variety of substances including cytokines. The aim of this study was to examine the cytokine production in five uninfected patients. This work investigated the presence in dialysates of interleukin-1ß, interleukin-6, interleukin-8, tumor necrosis factor α and the ability of peritoneal macrophages to produce these cytokines. These results were compared with values obtained from control group in non-uremic conditions (peritoneal lavage with isotonic saline or dialysis fluid). All cytokines were detectable in dialysates. Interindividual variations in cytokine concentration in dialysates were wider than variations of production of cytokines ex vivo by stimulated and unstimulated cells. In control group, dialysis fluid inhibited the cytokine production and with isotonic saline, cells produced less cytokines than dialysis patients'cells. The highest levels of interleukin-1 and tumor necrosis factor in dialysates and the highest capacity to respond to LPS were observed in patients having the shortest duration of dialysis. The variability observed did not seem to be due to cells themselves but to their environment.

A new method to evaluate anti-allergic effect of food component by measuring leukotriene B4 from a mouse mast cell line

Leukotrienes (LTs), chemical mediators produced by mast cells, play an important role in allergic symptoms such as food allergies and hay fever. We tried to construct an evaluation method for the anti-LTB₄ activity of chemical substances using a mast cell line, PB-3c. PB-3c pre-cultured with or without arachidonic acid (AA) was stimulated by calcium ionophore (A23187) for 20 min, and LTB₄ production by the cells was determined by HPLC with UV detection. LTB₄ was not detected when PB-3c was pre-cultured without AA. On the other hand, LTB₄ production by PB-3c pre-cultured with AA was detectable by HPLC, and the optimal conditions of PB-3c for LTB₄ detection were to utilize the cells pre-cultured with 50 µM AA for 48 h. MK-886 (5-lipoxygenase inhibitor) completely inhibited LTB₄ production, but AACOCF₃ (phospholipase A₂ inhibitor) slightly increased LTB₄ production, suggesting that LTB₄ was generated from exogenous free AA through 5-lipoxygenase pathway. We applied this technique to the evaluation of the anti-LTB₄ activity of food components. PB-3c pre-cultured with 50 µM AA for 48 h was stimulated with A23187 in the presence of 50 µM soybean isoflavones (daidzin, genistin, daidzein, and genistein), equol, quercetin, or kaempferol. Genistein, equol, quercetin, and kaempferol strongly inhibited LTB₄ production without cytotoxicity. These results suggest that a new assay system using PB-3c is convenient to evaluate LTB₄ inhibition activity by food components. This method could be utilized for elucidation of the mechanisms of LTB₄ release suppression by food components such as flavonoids and the structure-activity relationship.

Peritoneal inflammation precedes encapsulating peritoneal sclerosis: results from the GLOBAL Fluid Study

BACKGROUND

Encapsulating peritoneal sclerosis (EPS) is an uncommon condition, strongly associated with a long duration of peritoneal dialysis (PD), which is itself associated with increased fibrosis in the peritoneal membrane. The peritoneal membrane is inflamed during PD and inflammation is often associated with fibrosis. We hypothesized that patients who subsequently develop EPS might have a more inflamed peritoneal membrane during PD.

METHODS

We performed a nested, case-control study identifying all EPS cases in the UK arm of the GLOBAL Fluid Study and matching them by centre and duration of PD with two to three controls. Dialysate and plasma samples were taken during repeated peritoneal equilibration tests prior to cessation of PD from cases and controls. Samples were assayed by electrochemiluminescence immunoassay for interleukin-1β (IL-1β), tumour necrosis factor α (TNF-α), interferon-γ (IFN-γ) and IL-6. Results were analysed by linear mixed models adjusted for age and time on PD.

RESULTS

Eleven EPS cases were matched with 26 controls. Dialysate TNF-α {0.64 [95% confidence interval (CI) 0.23, 1.05]} and IL-6 [0.79 (95% CI 0.03, 1.56)] were significantly higher in EPS cases, while IL-1β [1.06 (95% CI -0.11, 2.23)] and IFN-γ [0.62 (95% CI -0.06, 1.29)] showed a similar trend. Only IL-6 was significantly higher in the plasma [0.42 (95% CI 0.07, 0.78)]. Solute transport was not significantly different between cases and controls but did increase in both groups with the duration of PD.

CONCLUSIONS

The peritoneal cavity has higher levels of inflammatory cytokines during PD in patients who subsequently develop EPS, but neither inflammatory cytokines nor peritoneal solute transport clearly discriminates EPS cases. Increased systemic inflammation is also evident and is probably driven by increased peritoneal inflammation.

Glucose degradation products (GDP) retard remesothelialization independently of d-glucose concentration

BACKGROUND

Glucose degradation products (GDP) present in heat-sterilized dialysis fluids are thought to contribute to cellular dysfunction and membrane damage during peritoneal dialysis. To examine the effects of specific GDP on the remesothelialization process, the impact of conventional and low GDP peritoneal dialysis solutions, D-glucose, and individual GDP in a scratch-wounding model was assessed.

METHODS

Scratch (0.5 to 0.6 mm)-wounded human peritoneal mesothelial cells (HPMC) were treated, at pH 7.4, with either (1) control medium (M199), (2) laboratory-prepared heat or filter-sterilized solutions, (3) 10% to 80% vol/vol solution of Gambrosol or Gambrosol-trio (1.5% and 4.0% glucose), (4) D-glucose (5 to 80 mmol/L), or (5) individual or combined GDP [acetaldehyde, formaldehyde, glyoxal, methylglyoxal, 3-deoxyglucosone (3-DG), 5-hydroxy methylfufural (5-HMF), or 3,4-di-deoxyglucosone-3-ene (3,4-DGE)]. Wound closure was recorded by time-lapse photomicroscopy.

RESULTS

In untreated HPMC, the rate of wound closure was linear and the process was complete by 18.4 +/- 3.6 hours (N = 16). In wounded HPMC exposed to dilutions of heat-sterilized but not filtered laboratory solutions (1.5% or 4.0% glucose, pH 7.4), remesothelialization was significantly retarded (P = 0.04 and P = 0.009 vs. M199, respectively). In Gambrosol, remesothelialization was significantly retarded in both 1.5% and 4.0% solutions. In contrast in Gambrosol-trio-treated HPMC, this rate was not significantly reduced in either 1.5% or 4.0% glucose peritoneal dialysis fluids. Remesothelialization was dose-dependently retarded in HPMC exposed to 3,4-DGE (>10 microl/L), formaldehyde (>5 micromol/L) but not by exposure to the other GDP tested even at 5 times the concentration present in low glucose solutions. The rate of remesothelialization was not significantly altered by exposure to D-glucose concentrations up to 80 mmol/L.

CONCLUSION

These data identify that the formaldehyde and 3,4-DGE present in heat-sterilized peritoneal dialysis solutions are important in reducing mesothelial cell regeneration. Specifically targeting their removal may have major benefits in preserving the mesothelium during long-term peritoneal dialysis.

Host defenses in APD

The incidence of peritonitis in peritoneal dialysis (PD) has further decreased after the introduction of automated peritoneal dialysis (APD) into clinical routine. Technical advances such as a reduction in the number of connections, more motivated patients, and improved host defense mechanisms in APD have been described. We found that the long daytime interval without dialysate exchanges leads to a higher absolute number of peritoneal macrophages which are capable of an improved first-line host defense. This is demonstrated by a higher release of cytokines of peritoneal macrophages after stimulation with lipopolysaccharides. The dry "day" in nightly intermittent PD seems to have no relevant additional positive effects on peritoneal host defense compared to continuous cyclic peritoneal dialysis. The regeneration of peritoneal cell populations induced by intervals without PD remains relevant even in times when more "biocompatible" PD solutions become available.

Hormonal regulation of sodium/sulfate co-transport in renal epithelial cells

Serum sulfate concentrations are elevated in infants, young children, and pregnant women due, at least in part, to increased renal sulfate reabsorption. Little is known about the effects of hormones, particularly those involved in growth, development, and pregnancy, on renal sulfate reabsorption. The objective of this investigation was to examine the effects of growth hormone (GH), insulin-like growth factor 1 (IGF-1), progesterone (PG), and 17beta-estradiol (EST) on renal sodium/sulfate co-transport. 35S-sulfate uptake was determined in Madin-Darby canine kidney (MDCK)/NaSi-1 cells (MDCK cells that have been stably transfected with rat sodium/sulfate co-transporter (NaSi-1) cDNA) and in opossum kidney (OK) cells. NaSi-1 mRNA was determined by RT-PCR and protein levels by ELISA. GH (0.1 nM) significantly increased the sodium/sulfate co-transport in MDCK/NaSi-1 cells up to 35%. IGF-1 induced a concentration-related stimulation of the sodium/sulfate co-transport with a maximal response observed at 1000 nM (59% increase). Sodium-dependent sulfate uptake was significantly increased when cells were preincubated with 10 nM PG, 10 nM EST, or 10 nM PG/10 nM EST up to 41%, 46%, or 39%, respectively. OK cells exhibited endogenous sodium-dependent sulfate transport; significantly increased sodium/sulfate co-transport was also observed in OK cells that were preincubated with GH, IGF-1, and PG/EST, although not with EST alone. The NaSi-1 mRNA and NaSi-1 protein levels were significantly increased in MDCK/NaSi-1 cells treated with 0.1 nM GH, 100 nM IGF-1, 10 nM PG, and/or 10 nM EST compared with control. These results suggest that the increased renal sulfate reabsorption that occurs in neonates, young and pregnant humans, and animals could be mediated by the increased steady-state levels of NaSi-1 mRNA produced by the higher plasma concentrations of GH, IGF-1, or PG/EST.

Experimental models in peritoneal dialysis: a European experience

BACKGROUND

The development of adequate animal models is important for the in vivo study of selected aspects of peritoneal dialysis (PD) that cannot be evaluated by an in vitro model, such as peritoneal membrane transport, the influence of local defense mechanisms, and for testing new osmotic agents and their biocompatibilities.

METHODS

Our experience with animal models for PD, including the acute Stockholm model in non-uremic rats, the acute and chronic Amsterdam model in non-uremic rats, and the chronic Gent model in uremic rats, is described.

RESULTS

The Stockholm model proved to be useful in understanding the normal physiology of peritoneal transport, and for testing new dialysis solutions and their biocompatibilities. It is a rather simple and inexpensive model, and thus is suitable for screening new solutions and additives. The Amsterdam model permits the study of chemokines and mesothelial cell regeneration in vivo, and is applied in a model of chronic peritonitis. The results of the Gent model suggest that chronic peritoneal dialysis in uremic rats is feasible for at least eight weeks. This model is, however, very laborious, time consuming, and expensive.

CONCLUSION

Further improvement of the technique and increase of the dialysis dose should result in a better and more realistic model for peritoneal dialysis. It is hoped that in the future these models will be useful to test the effects of long-term intraperitoneal application of different dialysis solutions and additives in uremic animals.

Longitudinal evaluation of peritoneal macrophage function and activation during CAPD: maturity, cytokine synthesis and arachidonic acid metabolism

The release of cytokines and prostaglandins (PG) by peritoneal macrophages (PM luminal diameter of) may influence the cytokine network controlling peritoneal inflammation and in the long-term the function of the peritoneum as a dialysis membrane. In the present study, an evaluation of the long-term effects of peritoneal dialysis on the release of cytokines and prostaglandins, and the expression of surface markers of cellular maturation on blood and mononuclear cells has been performed in patients during their first year on CAPD. Spontaneous release of tumour necrosis factor alpha (TNF alpha) and interleukins 6 (IL-6) by PM luminal diameter of, after 4 or 24 hours in culture, increased significantly with time on CAPD, while there was a small but significant decrease in release of prostaglandin E2 (PGE2). Production of TNF alpha and IL-6 was enhanced following incubation of the cells with lipopolysaccharide (LPS), but the effect of LPS was proportionally greater on blood monocytes than on PM luminal diameter of. There was a significant increase in the concentrations of PGE2 and 6-keto-prostaglandin F1 alpha in overnight dwell peritoneal dialysis effluent with time on CAPD. The levels of TNF alpha and IL-6 in uninfected PDE were below the detection limit of the immunoassay over the whole time period studied. Expression of CD15, which correlates with immaturity, by PM luminal diameter of and blood monocytes increased with time on CAPD, while expression of CD11c, a marker of maturation, decreased on blood monocytes, but did not change significantly on PM luminal diameter of. There was also a slight increase in expression of transferrin receptor in both PM luminal diameter of and monocytes, but this did not reach statistical significance. These findings suggest that peritoneal macrophages and blood monocytes isolated from CAPD patients over a one year period become increasingly immature with time, and this is accompanied by a significant modulation of their ability to secrete inflammatory cytokines. Dysregulation of macrophage function may have important consequences with respect to inflammatory processes and the long-term function of the peritoneal membrane in CAPD patients.

Methods for studying immuno-effector functions and antigen presenting activity of human macrophages

Macrophages are now recognized as cells that perform a variety of functions making them important cells in both the specific and non-specific immune responses. In the inflammatory response mature monocytes leave the bloodstream to enter macrophages and then migrate to the site of infection. This process is usually co-ordinated by the production of so-called chemotaxins that direct the movements of the macrophages. This can be measured in vitro by a chemotaxis assay that separates macrophages from the chemotactic fluid by a micropore filter. After incubation migrated cells are counted at the other side of the filter and indicate the chemotactic response. At the inflammatory site phagocytosis and killing of invading bacterial micro-organisms is an important feature of macrophages. We describe an assay to measure phagocytosing capacity using IgG-coated sheep red blood cells and a bacterial killing assay. In addition a tumor killing assay is briefly introduced. Finally, the specific immune response is initiated by presentation of antigen to antigen specific T cells by specialized cells such as dendritic cells that are closely related to macrophages. An enrichment procedure for macrophages and dendritic cells is outlined and antigen presentation assays are described.

Intraperitoneal production of erythropoietin with continuous ambulatory peritoneal dialysis

Higher hematocrit and serum erythropoietin (EPO) levels have previously been shown in end-stage renal disease patients treated with continuous ambulatory peritoneal dialysis (CAPD) compared with hemodialysis. We investigated whether EPO was produced intraperitoneally in CAPD patients. EPO concentration was 3.5 +/- 0.3 mU/ml by radioimmunoassay in 26 samples of peritoneal dialysis effluent obtained from 15 CAPD patients. EPO was not detectable in the fresh unused dialysate. No correlation was observed between EPO levels in the serum and dialysis effluent. Peritoneal macrophages were isolated from the dialysis effluent of 9 CAPD patients after an overnight dwell. The culture supernatant obtained after 24 h of in vitro culture of a million cells yielded EPO of 3.5 +/- 0.3 mU/ml. Our study demonstrated that peritoneal macrophages from CAPD patients produce EPO on in vitro stimulation, and EPO is present in the dialysis effluent of CAPD patients.

Immuno-effector characteristics of peritoneal cells during CAPD treatment: a longitudinal study

Peritoneal cells (PC) from 75 patients were immuno-phenotypically and functionally characterized during the first year of CAPD treatment (PCcapd) and compared to PC obtained by laparoscopy of healthy women (control peritoneal cells). Patients were divided, according to their peritonitis incidence (PI), into a high PI (HPI) and a low PI group (LPI). The yield of PCcapd decreased significantly over the year. The differential cell count and immunophenotype of PCcapd remained unchanged in the LPI group, but the percentage of macrophages decreased over the year in the HPI group. Macrophages in the PCcapd, when compared to control peritoneal cells, had a less mature phenotype as measured by RFD7 expression but a higher Fc-receptor expression. The PCcapd showed a higher percentage of B cells, CD4 positive T cells and activated T cells bearing HLA-DR/DQ when compared to the control peritoneal cells. Over the year a decrease in chemotactic activity of the PCcapd towards 10(-8) M N-formylmethionyl-leucyl-phenylalanine and dialysis effluent was observed in LPI patients but not in HPI patients. After one year of treatment, a significantly higher percentage of phagocytosing macrophages in the PCcapd of HPI patients was found when compared to LPI patients. During the year there was an increase of immunophagocytosis of PCcapd independent of PI. In conclusion, the CAPD peritoneal cellular immune system showed signs of both immaturity and activation. The decrease in the yield and in the chemotactic activity of PCcapd suggests an adaptation to the chronic stimulus of the dialysis fluid.(ABSTRACT TRUNCATED AT 250 WORDS)

Peritoneal cell labelling: a study on the migration of macrophages and dendritic cells towards the gut

In this study the migration of peritoneal cells was investigated by a fluorescence labelling technique. We found that peritoneal cells migrate to the subcapsular sinus and medulla of the parathymic lymph node (PTLN) and paratracheal lymph node (PTrLN). It was also observed that fluorescence labelled cells possibly granulocytes, macrophages and dendritic cells were found in the B cell follicles of Peyer patches and the dome area after intraperitoneal (ip) labelling. The implication of the migration of antigen presenting cells to the gut on the mucosal immune response is discussed.

The role of insulin-like growth factors and IGF-binding proteins in the physiological and pathological processes of the kidney

Insulin-like growth factors (IGFs) and their binding proteins are implicated in the growth regulation of the kidney during embryogenesis and differentiation. Recent evidence also suggests that IGFs play a role in kidney physiology (glomerular filtration rate, renal plasma flow) and pathology (diabetic renal hypertrophy, nephritis, glomerulosclerosis, kidney tumours, chronic renal failure). This review focuses on the biology of IGFs at the molecular, protein and receptor levels and considers their importance in renal physiology and pathology. The current data demonstrate a central role for the IGFs in the mediation of a wide variety of effects on renal growth, function and malignancy.

Accelerated growth in short children with chronic renal failure treated with both strict dietary therapy and recombinant growth hormone

In a 12-month study, nine boys, aged 4.8-15.6 years, with bone ages 4.6-13 years, with moderate to severe chronic renal failure and resultant growth failure were treated with daily recombinant human growth hormone (rhGH), in conjunction with a strict low-protein/low-phosphate diet supplemented with keto and amino forms of the essential amino acids, histidine and additional energy. Improved growth had previously been observed with this dietary management over that obtained with conventional treatment for chronic renal failure. Each child had been on this diet for at least 2 years before rhGH was commenced. Mean height velocity increased from 4.6 +/- 1.3 to 9.0 +/- 1.3 cm/year (P < 0.001) in the pre-pubertal group, and in the pubertal group from 5.4 +/- 1.4 to 10.4 +/- 1.8 cm/year (P < 0.01). The mean height velocity standard deviation scores (SDSs) increased from -1.2 +/- 0.6 to +2.3 +/- 0.9 (P < 0.001) in the pre-pubertal group and from -0.4 +/- 0.6 to +1.9 +/- 1.1 (P < 0.01) in the pubertal group. Mean height SDS for chronological age increased from -2.2 +/- 0.7 to -1.5 +/- 0.5 (P < 0.01) in the pre-pubertal group and from -1.9 +/- 0.7 to -1.3 +/- 0.9 in the pubertal group (P < 0.02). There was no significant deterioration in renal function or renal bone disease, and bone age did not advance more than chronological age over the 12-month period.

Effects of the color additive caramel color III and 2-acetyl-4(5)-tetrahydroxybutylimidazole (THI) on the immune system of rats

Administration of ammonia caramel color (AC) to rats may decrease blood lymphocyte counts, specifically in rats fed a diet low in vitamin B6. This effect is associated with 2-acetyl-4(5)-(1,2,3,4-tetrahydroxybutyl)imidazole (THI). To characterize and compare the effects of AC and THI and to study the influence of dietary pyridoxine, two studies in rats were conducted. Weanling rats fed a diet containing 2-3 ppm pyridoxine and exposed to 4% AC or 5.72 ppm THI in drinking water for 4 weeks showed reduced cell numbers in spleen and popliteal lymph nodes, as well as in the blood. Flow cytometric analyses demonstrated a comparable reduction in B and T lymphocytes. In blood, spleen, and popliteal lymph nodes, CD4+ lymphocytes were more reduced than CD8+ cells. The number of bone marrow cells was not affected. Although thymus weight and cell number were not affected either, a decreased cortex over medulla area ratio and an increase in medullary cell density largely due to an increase in CD4+ thymocytes was observed. Decreased numbers of ED2+ macrophages were observed in the thymic cortex and in the spleen red pulp. All effects observed were either less pronounced or absent in a study with rats fed a diet containing 11-12 ppm pyridoxine. The effects of AC and THI on the immune system were similar. Whereas AC exposure was associated with changes in vitamin B6 status, THI did not induce obvious effects on vitamin B6 parameters. It is proposed that the effects of AC and THI on the immune system are not caused by a disturbance of vitamin B6 metabolism, but may in fact result from a disturbance of a specific PLP-dependent process.

Replication of human immunodeficiency virus type 1 in primary dendritic cell cultures

The ability of the human immunodeficiency virus type 1 (HIV-1) to replicate in primary blood dendritic cells was investigated. Dendritic cells compose less than 1% of the circulating leukocytes and are nondividing cells. Highly purified preparations of dendritic cells were obtained using recent advances in cell fractionation. The results of these experiments show that dendritic cells, in contrast to monocytes and T cells, support the active replication of all strains of HIV-1 tested, including T-cell tropic and monocyte/macrophage tropic isolates. The dendritic cell cultures supported much more virus production than did cultures of primary unseparated T cells, CD4+ T cells, and adherent as well as nonadherent monocytes. Replication of HIV-1 in dendritic cells produces no noticeable cytopathic effect nor does it decrease total cell number. The ability of the nonreplicating dendritic cells to support high levels of replication of HIV-1 suggests that this antigen-presenting cell population, which is also capable of supporting clonal T-cell growth, may play a central role in HIV pathogenesis, serving as a source of continued infection of CD4+ T cells and as a reservoir of virus infection.

Chemotaxis of the peritoneal cells and the detection of a chemo-attractant in the effluent from peritoneal dialysis patients

The migration of peritoneal cells from 25 continuous ambulatory peritoneal dialysis patients and eight healthy women undergoing laparoscopy were studied. Peritoneal cells of continuous ambulatory peritoneal dialysis patients migrated to commonly used chemoattractants, like N-formyl-methionyl-leucyl-phenyl-alanine-methyl- ester and casein, but they also migrated to high concentrations of recombinant interleukin-1 alpha and to endotoxin (lipopolysaccharide). In the peritoneal effluent from continuous ambulatory peritoneal dialysis patients a rather heat stable chemoattractant was found with a molecular weight of 40-200 kDa with an optimal activity at approximately 125 kDa. The chemoattractant is a protein and is not complement factor 5a or interleukin-1 and was only found in peritoneal effluent from continuous ambulatory peritoneal dialysis patients, but not in peritoneal fluid from healthy women undergoing laparoscopy. Therefore, peritoneal dialysis might induce the generation of a chemoattractant. The optimal chemotactic response of peritoneal cells from continuous ambulatory peritoneal dialysis patients to N-formyl-methionyl-leucyl-phenyl-alanine-methyl- ester in medium could be enhanced by replacing the medium by peritoneal effluent. So the chemotaxis of peritoneal cells to the factor in the peritoneal effluent is caused by another mechanism, which might involve different cell surface receptor populations, than the chemotactic response to N-formyl-methionyl-leucyl-phenyl-alanine-methyl-ester.