Podoplanin-positive cells are a hallmark of encapsulating peritoneal sclerosis.

BACKGROUND: Encapsulating peritoneal sclerosis (EPS) and simple peritoneal sclerosis are important complications of long-term peritoneal dialysis (PD). Podoplanin is expressed by mesothelial cells and lymphatic vessels, which are involved in inflammatory reactions in the peritoneal cavity. METHODS: We studied 69 peritoneal biopsies from patients on PD (n = 16), patients with EPS (n = 18) and control biopsies taken at the time of hernia repair (n = 15) or appendectomy (n = 20). Immunohistochemistry was performed to localize podoplanin. Additionally, markers of endothelial cells, mesothelial cells, myofibroblasts (smooth muscle actin), proliferating cells, and double labelling for smooth muscle actin/podoplanin were used on selected biopsies. RESULTS: Podoplanin was present on the endothelium of lymphatic vessels in the submesothelial fibrous tissue and on mesothelial cells. In patients on PD and in biopsies with appendicitis, the mesothelial cells demonstrated a cuboidal appearance and circumferential podoplanin staining, with gaps between the cells. The number of lymphatic vessels was variable, but prominent at sites of fibrosis. In patients with EPS, a diffuse infiltration of podoplanin-positive cells with a fibroblastic appearance was present in 15 out of 18 biopsies. This pattern was focally present in 3 out of 16 on PD and none in the 35 controls. The podoplanin-positive cells did not express the endothelial marker or the mesothelial marker (calretinin). CONCLUSIONS: EPS is characterized by a population of podoplanin and smooth muscle actin double-positive cells. Podoplanin might be a suitable morphological marker supporting the diagnosis and might be involved in the pathogenesis of EPS.

Peritoneal mast cells in peritoneal dialysis patients, particularly in encapsulating peritoneal sclerosis patients.

BACKGROUND: We assumed that increased mast cell numbers contribute substantially to the fibrosis often seen in the peritoneum of peritoneal dialysis (PD) patients, particularly those with encapsulating peritoneal fibrosis (EPS). Therefore, we investigated mast cells in different pathological conditions of the peritoneum. METHODS: One hundred fifteen tissue probes with different peritoneal pathological states were selected (normal, n = 20; chronic appendicitis, n = 25; herniotomy, n = 24; fibrosis, n = 11; PD, n = 26; and EPS, n = 9). For staining of mast cells, we used alpha-naphtol-AS-d-chloracetate-esterase and mast cell tryptase. Next, we counted numbers of mast cells per square millimeter. Tryptase was measured by using image analysis. RESULTS: Measurements by means of both methods correlated well (r = 0.812). Numbers of mast cells per square millimeter were as follows: normal, 26 +/- 16; chronic appendicitis, 241 +/- 217; herniotomy, 115 +/- 88; fibrosis, 99 +/- 66; PD, 81 +/- 64, and EPS, 24 +/- 23 (P = 0.00006). Amounts of tryptase present were 2.900 +/- 0.118, 2.871 +/- 0.150, 2.733 +/- 0.183, 3.041 +/- 0.176, 2.780 +/- 0.184, and 2.609 +/- 0.234, respectively (P = 0.00002). CONCLUSION: We found upregulation of mast cells in specimens of chronic inflammatory diseases of the peritoneum. This also was true for PD patients, with the exclusion of patients with EPS. Therefore, loss-of-control functions of mast cells may contribute to the ill-understood disease entity of EPS.

The expression patterns of peritoneal defensins.

BACKGROUND: Local defense mechanisms are important for the integrity of the peritoneum, but few details are known about the expression patterns of antimicrobial proteins such as human defensin in normal and damaged peritoneum. METHODS: Part A: The expression of different defensins in normal (n = 12), inflamed (n = 5), and metastatic peritoneum (n = 4) and in cultured human peritoneal mesothelial cells was analyzed using mRNA and immunohistochemistry. Part B: Using immunohistochemistry the expression of different defensins was analyzed in different subgroups: healthy controls (n = 25), patients with chronic appendicitis (n = 25) or acute appendicitis (n = 10), and end-stage renal disease patients (n = 25, with 15 on peritoneal dialysis). RESULTS: Part A: Human neutrophil peptides (HNP) 1 and 3 and human beta-defensins (HBD) 1 to 3 mRNA were detected in peritoneal specimens. In addition, HNP1,3, HBD1, HBD2, and HBD3 proteins were detected using immunohistochemistry. Part B: HBD1 showed a constitutive expression in mesothelium, while HBD2 and HNP1,3 were associated with inflammation. Decreased expressions of HNP1,3 were observed in end-stage renal disease patients and in patients on peritoneal dialysis. CONCLUSIONS: For the first time, the expression patterns of defensins in normal and damaged peritoneum have been described. The reduced expression of some defensins in end-stage renal disease is of potential clinical interest against the background of the frequent infective complications seen in peritoneal dialysis.

Metallothionein and dendritic cells in skin of end-stage renal disease patients not on dialysis, or on hemodialysis or peritoneal dialysis.

OBJECTIVE: Renal failure leads to a variety of defects in immune function. The skin, as a major player in the immune system network, also exhibits multiple derangements. The pathogenesis of these defects and derangements are poorly understood; therefore, we studied immune competent cells, dermal dendrocytes (DC), and a special proinflammatory protein, metallothionein (MT), in the skin of these patients. DESIGN: 22 patients with end-stage renal disease (ESRD) but not on dialysis, 18 patients on hemodialysis (HD), 14 patients on peritoneal dialysis (PD), and 35 healthy controls were included in the study. Immunohistochemical staining of skin biopsies for DC and MT was performed with the following antibodies: for DC, antibody against factor XIIIa; and for MT, Dako-MT, E9 (Dako, Carpinteria, California, USA). Measurements were made by counting stained DC per square millimeter, and by optical density (OD) for MT (mean SEM). RESULTS: Metallothionein was increased in the skin of HD (OD 0.42 +/- 0.05, p < 0.01) and PD patients (OD 0.33 +/- 0.04, p < 0.05) compared to controls (OD 0.23 +/- 0.02) and ESRD patients not on dialysis (OD 0.22 +/- 0.05). In contrast, numbers of DC were reduced in patients on PD compared to controls (59 +/- 13 vs 96 +/- 59 DC/mm2, p < 0.01) and increased in patients with ESRD prior to dialysis (141 +/- 13 DC/mm2, p < 0.05). Patients on HD were in-between (105 +/- 20 DC/mm2), with a significant difference versus patients on PD (p < 0.05). CONCLUSIONS: Our data show that the mode of dialysis influences the number of antigen-presenting cells in the dermis. However, in both dialysis modes, a proinflammatory immune status of the skin (MT) was present and, therefore, other regulatory elements for dermal dendrocytes apart from proinflammation exist.

Gastrointestinal involvement in granulomatosis with polyangiitis and microscopic polyangiitis: histological features and outcome.

AIM: Gastrointestinal (GI) involvement in patients with granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA) is rare. METHOD: Medical charts of seven patients with GPA and MPA and GI involvement were reviewed regarding clinical presentation, outcome, diagnostic tools and therapy. Second, the cellular composition of the inflammatory infiltrate associated with the vascular lesions in histological samples (ileum, colon, rectum, duodenum) were investigated to identify possible treatment targets. Immunohistochemistry was done with antibodies against CD20, CD3 and CD34. Samples from a healthy control group (n = 15) were used for comparison. RESULTS: Mean age at onset of the first symptoms of vasculitis was 48 ± 21.3 years. At time of diagnosis GI symptoms were present in five out of seven patients (71%) and occurred during relapse of the vasculitis in two patients (29%). All patients had abdominal pain, four of seven (57%) had an acute kidney injury and three patients required renal replacement therapy. At the time of diagnosis five of seven patients (71%) required surgery and mean Birmingham Vasculitis Activity Score (BVAS) on admission was high (26.3 ± 7.7). Regarding outcome, one patient died due to gastrointestinal bleeding. Histological analysis showed significantly higher expression of CD3 in this patient compared to the control group (P = 0.02). Analysis of expression of CD20 and CD34 showed no statistically significant differences between patients with GPA and MPA with GI involvement compared to the control group. CONCLUSIONS: GI involvement in GPA and MPA is rare. Therapy directed at T cells might be an alternative treatment option.

Induction of metallothionein in mesothelial cells by zinc.

Patients on peritoneal dialysis (PD) are exposed to peritoneal dialysis fluids with unphysiological properties. Local defense systems are of importance. In this respect, metallothionein (MT) might play an important role. Because nothing is known about the achievability of MT induction in peritoneum by zinc, we performed the following study. We investigated human peritoneal mesothelial cells (HPMC) from omentum and a mesothelioma cell (MTC) line after addition of zinc in concentrations from 35 to 350 microM. Measurements of MT-mRNA and protein (by immuncytochemistry [IHC], Western blots, and dot blots) were performed. Zinc caused a clear and highly significant fourfold increase of RNA in MTC and to a lower extent in HPMC (1.6-fold, P < 0.001). IHC demonstrated a clear induction in HPMC and MTC. Western and dot blots confirmed this and showed an increase of MT from 112-mg/g total protein (TP) to 410-mg/g TP. Zinc was able to upregulate MT significantly in HPMC and MTC on the RNA and protein level. Fourfold increases of MT were achievable.

Induction of metallothionein in proximal tubular cells by zinc and its potential as an endogenous antioxidant.

BACKGROUND: This study was undertaken to gain further insights into the expression of metallothionein (MT) in kidney, to define the necessary dosage of a metal (zinc) to achieve induction of MT and to evaluate the antioxidative potential of MT in comparison to other more common antioxidative therapeutics, like N-acetyl-L-cysteine (NAC), and endogenous molecules, like glutathione. METHODS: MT was measured in renal specimens from cadaver kidneys from patients with chronic diseases (n = 76) and controls (n = 21) by immunohistochemistry. In addition, induction experiments were performed in cell cultures of proximal tubular cells (LCC-PK1) and MT measured on the RNA and protein level (immunohistochemistry, Western and dot blotting). Antioxidative potential of MT was compared to NAC and glutathione. RESULTS: MT was restricted to tubular cells with no differences between controls and patients. Zn caused a dose-dependent increase of MT on the RNA as well as on the protein level (RNA (ratio MT/histone 3.3): control 0.34 +/- 0.12; Zn 17 microM 0.65 +/- 0.26; Zn 35 microM 1.25 +/- 0.43 (p < 0.05), Zn 52 microM 1.35 +/- 0.46 (p < 0.05), and protein: 5.8-fold increase from 47 +/- 13 mg/g total protein (n = 6) to 272 +/- 140 mg/g total protein (n = 6)). The antioxidative effect of MT was equal to NAC and glutathione. CONCLUSIONS: Induction of renal MT by zinc is easily achievable and might be an interesting therapeutic and preventive tool against oxidative stress.

Apoptosis of mesothelial cells caused by unphysiological characteristics of peritoneal dialysis fluids.

There is an ongoing debate as to which peritoneal dialysis fluids (PDFs) provide the best preservation of peritoneal cells. To investigate this topic further, we measured apoptosis and necrosis of cultured mesothelial cells (MCs) after exposure to different single unphysiological features of PDFs and PDFs for whole. MCs were incubated in buffers containing plasticizers, high osmolarity by sodium chloride, low pH, and high glucose for 0.5, 4, and 24 h. The same procedure was repeated with different PDFs. Apoptosis and necrosis were measured by FACS-analysis (annexin-FITC and propidium iodide). We found that plasticizers were clearly able to induce apoptosis after 24 h (18 +/- 4%). The same result was observed with high osmolarity by sodium chloride (17 +/- 5%), but not for high glucose (9 +/- 8%). All fluids with low pH (5.2) caused severe and almost complete necrosis (after 4 and 24 h). Incubation in neutral, two-compartment PDFs (glucose 4.25%) without plasticizers for 4 h showed no significant necrosis (3%), but after 24 h apoptosis was detectable in 10 +/- 9% and necrosis in 29 +/- 8% of MCs. In conclusion, after improving PDFs and introducing neutral fluids, further attention should be drawn to inducers of apoptosis. Apoptosis can be detected quite early (24 h) and is caused by plasticizers and high osmolarity.

Osteoarthritis of the knee--clinical assessments and inflammatory markers.

OBJECTIVE: The present cross sectional study was performed to test the hypothesis that in osteoarthritis (OA) of the knee severity of this disease is related to local levels of inflammatory metabolites and their corresponding enzymes. METHODS: From 41 patients with OA of the knee (age range 45-79 years) undergoing arthroscopy blood, synovial fluid (SF) and synovial membrane (SM) were collected. Clinical conditions were primarily assessed by the WOMAC-index and radiographic grading (K&L-grade). Concentrations of PGE(2), TxB(2)and NO(2/3)and that of IL-6, IL-1 alpha, IL-1 beta, TNF alpha, COX-2 and iNOS were determined in SF and SM, respectively. RESULTS: With advancing age K&L-grade and COX-2 in SM increased significantly (P=0.005 and P=0.01, respectively). TNF alpha and IL-1 alpha were not detectable in SM samples. Apart from a correlation between PGE(2)and WOMAC-index (r=0.36, P=0.035) no significant relationships could be found between the various inflammatory parameters and any of the assessed clinical signs. CONCLUSIONS: Apparently no direct relationships exist between the measured markers of inflammation (e.g. PGE(2), NO(2/3)) or the involved enzymes (e.g. COX-2, iNOS) and the severity of OA of the knee. The degenerative condition of this disease might be due to the more local, mainly mechanical injury with little systemic upset. However, further longitudinal studies are needed to clarify whether the assessed biochemical markers could serve as predictors for the progression of OA.

Naltrexone does not relieve uremic pruritus: results of a randomized, double-blind, placebo-controlled crossover study.

Improvement of uremic pruritus was reported under short-term administration of the mu-receptor antagonists naltrexone and naloxone. The aim of the present study was to confirm the efficacy and safety of the oral mu-receptor antagonist naltrexone during a 4-wk treatment period in patients on hemodialysis and peritoneal dialysis. A placebo-controlled, double-blind crossover study of uremic patients with persistent, treatment-resistant pruritus was performed. Of 422 patients screened between December 1997 and June 1998, 93 suffered from pruritus and 23 were eligible for the study. Patients were started either with a 4-wk naltrexone sequence (50 mg/d) or matched placebo. This was followed by a 7-d washout, and patients continued with a 4-wk sequence of the alternate medication. Pruritus intensity was scored daily by a visual analogue scale (VAS) and weekly by a detailed score assessing scratching activity, distribution of pruritus, and frequency of pruritus-related sleep disturbance. Sixteen of 23 patients completed the study. During the naltrexone period, pruritus decreased by 29.2% (95% confidence interval [CI], 18.7 to 39.6) on the VAS and by 17.6% (95% CI, 4.2 to 31.1) on the detailed score. In comparison, pruritus decreased by 16.9% (95% CI, 6.8 to 26.9) on the VAS and by 22.3% (95% CI, 9.3 to 35.2) on the detailed score during the placebo period. The difference between the naltrexone and the placebo treatment period was not statistically significant. Nine of 23 patients complained of gastrointestinal disturbances during the naltrexone period compared with only one of 23 patients during the placebo period (P < 0.05). These results show that treatment of uremic pruritus with naltrexone is ineffective. In addition, a high incidence of adverse effects was observed during treatment with naltrexone.