TGF-β1 Promotes Lymphangiogenesis during Peritoneal Fibrosis

Peritoneal fibrosis (PF) causes ultrafiltration failure (UFF) and is a complicating factor in long-term peritoneal dialysis. Lymphatic reabsorption also may contribute to UFF, but little is known about lymphangiogenesis in patients with UFF and peritonitis. We studied the role of the lymphangiogenesis mediator vascular endothelial growth factor-C (VEGF-C) in human dialysate effluents, peritoneal tissues, and peritoneal mesothelial cells (HPMCs). Dialysate VEGF-C concentration correlated positively with the dialysate-to-plasma ratio of creatinine (D/P Cr) and the dialysate TGF-β1 concentration. Peritoneal tissue from patients with UFF expressed higher levels of VEGF-C, lymphatic endothelial hyaluronan receptor-1 (LYVE-1), and podoplanin mRNA and contained more lymphatic vessels than tissue from patients without UFF. Furthermore, mesothelial cell and macrophage expression of VEGF-C increased in the peritoneal membranes of patients with UFF and peritonitis. In cultured mesothelial cells, TGF-β1 upregulated the expression of VEGF-C mRNA and protein, and this upregulation was suppressed by a TGF-β type I receptor (TGFβR-I) inhibitor. TGF-β1–induced upregulation of VEGF-C mRNA expression in cultured HPMCs correlated with the D/P Cr of the patient from whom the HPMCs were derived (P<0.001). Moreover, treatment with a TGFβR-I inhibitor suppressed the enhanced lymphangiogenesis and VEGF-C expression associated with fibrosis in a rat model of PF. These results suggest that lymphangiogenesis associates with fibrosis through the TGF-β–VEGF-C pathway.The decrease in ultrafiltration capacity that is associated with the high peritoneal solute transport that is observed after prolonged peritoneal dialysis (PD) treatment is a major reason for its discontinuation.^1–4 Several studies have shown that a higher peritoneal solute transport rate is associated with reduced survival of PD patients.^1,2,5 The characteristic features of chronic peritoneal damage in PD treatment are associated with submesothelial fibrosis and neoangiogenesis.^6,7 Analyses of the surface peritoneum showed no significant changes in vessel density with duration of PD.^6,8 In addition, the vessel density in patients with ultrafiltration failure (UFF) was significantly higher than the vessel density in normal individuals or non-PD patients, but it was not higher than the vessel density in patients undergoing PD.⁶ These findings suggest that factors other than increased vascular density may be involved in disease states associated with increased transport of peritoneal membranes. In addition, the relationship between peritoneal fibrosis and UFF remains obscure.Blood capillaries have a continuous basal lamina with tight interendothelial junctions and are supported by pericytes and smooth muscle cells. In contrast, lymphatic capillaries are thin-walled with a wide lumen and do not contain pericytes or basement membrane. The structures of lymphatic vessels are suitable for the removal of tissue fluid, cells, and macromolecules from the interstitium.^9–11 If lymphangiogenesis develops in the peritoneal membrane, absorption of the PD fluid could be increased and lead to UFF. An increase in the number of lymphatic vessels has recently been reported in several disease conditions, including tumor metastasis,^12–15 chronic respiratory inflammatory diseases,^16–18 wound healing,¹⁹ and renal transplant rejection.^20,21 We recently reported that lymphangiogenesis had developed in tubulointerstitial fibrosis of human renal biopsy specimens,²² and we also reported the mechanisms of lymphangiogenesis in rat unilateral ureteral obstruction models.²³The lymphatic absorption rate, which is measured by the rate at which intraperitoneally administered radioactive serum albumin or macromolecule dextran 70 disappears, is significantly higher in patients with UFF, and lymphatic reabsorption is considered to be one of the causes of UFF.^24–27 However, the results from these clinical approaches have been controversial.^28,29 In addition, little is known about the pathology and the process of lymphangiogenesis in patients with UFF and peritonitis.In this study, we investigated lymphangiogenesis and the expression of vascular endothelial growth factor-C (VEGF-C), which is a potentially important mediator of lymphangiogenesis, in human peritoneal tissues, PD effluent, and peritoneal mesothelial cells. We also explored VEGF-C induction by TGF-β1 in the human mesothelial cell line (Met-5A) and cultured human peritoneal mesothelial cells (HPMCs) from the spent PD effluent of patients with varying rates of peritoneal transport. Finally, we explored the relationship between peritoneal fibrosis and lymphangiogenesis in rats that were administered chlorhexidine gluconate (CG) into the abdominal cavity, which provides a model of chemically induced peritoneal inflammation/fibrosis.^30–32 This work is the first report to show that lymphangiogenesis is linked to the peritoneal fibrosis that is often associated with a high peritoneal transport rate.     

A new method for peptidase activity measurement in serum and tissues, using L-Leu-L-Leu as substrate.

Peptidase-free L-amino-acid oxidase was purified from venom of Agkistrodon caliginosus and was used for the determination of serum peptidase (EC 3.4.1.-) activity with L-Leu-L-Leu as substrate. The peptidase activity in human serum rose remarkably in liver diseases, and had a significant correlation with serum transaminase activity. The peptidase activity in serum of rats treated with CCl4 was higher than that of normal rats. After Cellogel electrophoresis the zymogram of peptidase from human liver using di- or tripeptide as substrate appeared with three active bands; however, peptidase in serum of a patient with acute hepatitis showed only one active band.     

Concanavalin A- or phorbol ester-induced translocation of protein kinase C in thymoma cells from a patient with myasthenia gravis

We have examined the localization of phospholipid/calcium-dependent protein kinase (protein kinase C) in thymoma cells, which were resected from a patient with myasthenia gravis. Upon stimulation with 4 micrograms/ml of concanavalin A (Con A) for 30 min, protein kinase C activity in the cytosolic fraction was increased from 7.44 pmol/min per 10(7) cells to 11.42 pmol/min per 10(7) cells. On the other hand, membrane-associated protein kinase C activity was decreased from 1.69 to 0.71 pmol/min per 10(7) cells. On the contrary, 10(-7) mol/l tetradecanoyl phorbol acetate (TPA) decreased cytosolic protein kinase C activity from 9.31 to 8.04 pmol/min per 10(7) cells, while membrane-associated protein kinase C activity was increased from 1.69 to 2.94 pmol/min per 10(7) cells. Several endogenous phosphorylated proteins (mol wt 20,000, 23,000) were observed as inferred by SDS-polyacrylamide gel electrophoresis. These findings indicated that Con A and TPA produce differential translocation of protein kinase C.     

Aortic regurgitation: ventricular response after aortic valve replacement

This study was designed to evaluate the usefulness of the ratio of the preoperative regurgitant stroke volume to left ventricular end-diastolic volume (RSV/LVEDV) for assessing the left ventricular function preoperatively. In 26 patients with aortic regurgitation (AR), the percent decrease in LVEDV was compared with the preoperative RSV/LVEDV, ejection fraction (EF), LVEDV, left ventricular end-systolic volume (LVESV) or left ventricular end-diastolic pressure (LVEDP). There was a significant correlation between the percent decrease in LVEDV and RSV/LVEDV. Patients with RSV/LVEDV of more than 0.26 had a significantly smaller postoperative left ventricular end-diastolic volume index (LVEDVI) and left ventricular end-systolic volume index (LVESVI), and a greater postoperative EF than patients with smaller RSV/LVEDV. All but one patient with RSI/LVEDVI larger than 0.0016 LVEDVI had normal postoperative LVEDVI. Based on these findings, it is concluded that the RSV/LVEDV is an useful indicator for preoperative evaluation of left ventricular functions in patients with AR. Surgical intervention for patients with AR should be recommended before the RSI/LVEDVI drops to less than 0.0016 LVEDVI, to expect good postoperative ventricular responses.     

Lead exposure during breastfeeding

QUESTION Owing to the recent concerns of lead (Pb) leaking into tap water, one of our female patients is concerned about the effects of Pb exposure to newborns while breastfeeding. How should I advise her and should she switch to formula feeding?ANSWER Lead exposure through drinking tap water while breastfeeding is not associated with any serious concerns in most available studies. There is currently no safe level of Pb exposure, but environmental exposure within Canada is low. At present, Pb levels in drinking water are carefully monitored by Health Canada and are not likely to be of concern to breastfeeding mothers. Switching to formula feeding is not necessary and not recommended, as improperly prepared formula can have higher Pb levels.     

Effect of FR167653, a novel inhibitor of tumor necrosis factor-alpha and interleukin-1beta synthesis on lipopolysaccharide-induced hepatic microvascular dysfunction in mice

Tumor necrosis factor-alpha (TNFalpha) and interleukin-1 (IL-1) have been recognized as key proinflammatory mediators in the pathogenesis of lipopolysaccharide (LPS)-induced liver injury. In the present study we examined the effect of FR167653, a novel inhibitor of TNFalpha and IL-1 synthesis, on the hepatic microvascular response to LPS using in vivo microscopy. Significant hepatic microvascular responses comprising leukocyte adhesion to the sinusoidal wall and central venules and reduced sinusoidal perfusion appeared 2 and 4 h after LPS (0.1 mg/kg, i.v.) injection in male C3H/HeN mice (LPS sensitive) when compared with male C3H/HeJ mice (LPS resistant). The serum concentrations of TNFalpha at 1.5 h and IL-1beta at 4 h after injection of LPS, as determined by enzyme-linked immunosorbent assay, were significantly higher in C3H/HeN mice than in C3H/HeJ mice. Administration of murine TNFalpha or IL-1beta (10 microg/kg., i.v., respectively) in both C3H/HeN and C3H/HeJ mice elicited the hepatic microvascular responses that were similar to those produced by LPS injection in C3H/HeN mice. FR167653 (1 and 10 mg/kg, i.v., 0 and 2 h after LPS injection) significantly reduced leukocyte adhesion and restored sinusoidal perfusion in a dose-dependent manner in C3H/HeN mice 4 h after LPS injection. The levels of TNFalpha, IL-1beta, and alanine aminotransferase also were significantly lower in FR167653-treated endotoxemic C3H/HeN mice than those in vehicle-treated endotoxemic animals. The results suggest that the hepatic microvascular response to LPS is partly mediated by TNFalpha and IL-1beta, and that FR167653 prevents LPS-induced hepatic microcirculatory dysfunction by inhibiting the production of TNFalpha and IL-1beta.     

Correction to: Agarotetrol: a source compound for low molecular weight aromatic compounds from agarwood heating

Journal of Natural Medicines - In the original publication of the article, under the paragraphs “Collection of volatile compound” and “Analysis of essential oil and...