Pathophysiology of elevated ascites fluid cholesterol in malignant ascites. Increased ascites to serum relation of proteins and lipoproteins in patients with peritoneal carcinomatosis as compared to patients with cirrhosis of the liver

The IGF-PAPP-A-Stanniocalcin Axis in Serum and Ascites Associates with Prognosis in Patients with Ovarian Cancer

Pregnancy-associated plasma protein-A (PAPP-A) and PAPP-A2 modulate insulin-like growth factor (IGF) action and are inhibited by the stanniocalcins (STC1 and STC2). We previously demonstrated increased PAPP-A and IGF activity in ascites from women with ovarian carcinomas. In this prospective, longitudinal study of 107 women with ovarian cancer and ascites accumulation, we determined corresponding serum and ascites levels of IGF-1, IGF-2, PAPP-A, PAPP-A2, STC1, and STC2 and assessed their relationship with mortality. As compared to serum, we found highly increased ascites levels of PAPP-A (51-fold) and PAPP-A2 (4-fold). Elevated levels were also observed for IGF-1 (12%), STC1 (90%) and STC2 (68%). In contrast, IGF-2 was reduced by 29% in ascites. Patients were followed for a median of 38.4 months (range: 45 days to 8.9 years), during which 73 patients (68.2%) died. Overall survival was longer for patients with high serum IGF-1 (hazard ratio (HR) per doubling in protein concentration: 0.60, 95% CI: 0.40-0.90). However, patients with high ascites levels of IGF-1 showed a poorer prognosis (HR: 2.00 (1.26-3.27)). High serum and ascites IGF-2 levels were associated with increased risk of mortality (HR: 2.01 (1.22-3.30) and HR: 1.78 (1.24-2.54), respectively). Similarly, serum PAPP-A2 was associated with mortality (HR: 1.26 (1.08-1.48)). Our findings demonstrate the presence and activity of the IGF system in the local tumor ecosystem, which is likely a characteristic feature of malignant disease and plays a role in its peritoneal dissemination. The potential clinical implications are supported by our finding that serum levels of the proteins are associated with patient prognosis.

A Metabolomic Analysis of Cirrhotic Ascites

Ascites is a common complication of decompensated liver cirrhosis, and yet relatively little is known about its biochemical composition. We conducted two metabolomic investigations, comparing the profile of ascites from 33 cirrhotic patients and postoperative peritoneal drainage fluid from 33 surgical patients (Experiment 1). The profile of paired ascites and plasma was also compared in 17 cirrhotic patients (Experiment 2). Gas chromatography−mass spectrometry-based metabolomics identified 29 metabolites that significantly characterized ascites fluid, whether postoperative drainage fluid or plasma were used as controls. Ten elevated amino acids (glutamine, proline, histidine, tyrosine, glycine, valine, threonine, methionine, lysine, phenylalanine) and seven diminished lipids (laurate, myristate, palmitate, oleate, vaccenate, stearate, cholesterol) largely comprised the cirrhotic ascites metabolomic phenotype that differed significantly (adjusted p < 0.002 to 0.03) from peritoneal drainage fluid or plasma. The pattern of upregulated amino acids in cirrhotic ascites did not indicate albumin proteolysis by peritoneal bacteria. Bidirectional clustering showed that the more severe the cirrhosis, the lower the lipid concentration in ascitic fluid. The metabolomic compartment of ascites in patients with decompensated cirrhosis is characterized by increased amino acids and decreased lipids. These novel findings have potential relevance for diagnostic purposes.

Diagnostic utility of the serum-ascites albumin gradient in Mexican patients with ascites related to portal hypertension

Background and Aim

Analysis of ascitic fluid is necessary to determine the etiology and to distinguish portal hypertension (PH)‐related and unrelated ascites. Numerous diagnostic parameters have been studied, but no single parameter has completely distinguished these. We aimed to validate the serum albumin–ascites gradient (SAAG) for the diagnosis of ascites secondary to PH and to establish cutoff points to predict PH using its sensitivity and specificity.

Methods

This was a cross‐sectional study conducted on patients diagnosed with ascites of any etiology. The SAAG and albumin concentration in ascitic fluid (AFA) were measured to establish their sensitivity and specificity for determining the presence or absence of PH. Cutoff points and levels of statistical significance were established based on the area under the curve.

Results

Eighty‐seven patients were evaluated, of whom 74 (84%) were men, with an average age of 54.0 ± 13.6 years. Seventy‐two (83%) were diagnosed at admission with PH‐related ascites and 15 (17%) with non‐PH‐related ascites. SAAG correctly classified 48 (67%) patients, but 24 (33%) were classified incorrectly, while AFA classified 59 (82%) correctly and only 13 (17%) incorrectly. The diagnostic accuracy of SAAG was 57 versus 73% for AFA. AFA had a sensitivity of 82% and specificity of 66% (95% confidence interval [CI]: 0.63–0.93), while SAAG had a sensitivity of 66% but a specificity of 86% (95% CI: 0.72–0.95).

Conclusions

The SAAG showed poor diagnostic performance with low sensitivity but high specificity. The diagnostic accuracy of AFA is superior to that of SAAG in discriminating between PH and non‐PH ascites.

Diagnostic Utility of Serum Ascites Lipid and Protein Gradients in Differentiation of Ascites

CONTEXT

Ability of SAAG to differentiate malignant ascites from other aetiologies like tubercular peritonitis is a major problem. Alternate screening test is needed for differentiating ascites due to malignancy from those due to tubercular peritonitis.

AIMS

To study the diagnostic utility of serum ascites lipid gradients and serum ascites protein gradients in pathophysiological differentiation of ascites.

SETTINGS AND DESIGN

The present study is a prospective, descriptive, hospital-based, cross-sectional study.

METHODS AND MATERIAL

The study was conducted on patients with ascites who were admitted to General Medicine Department, Kasturba Hospital, Manipal. The study included 60 patients with ascites of different etiologies (liver cirrhosis, tubercular peritonitis, and malignant ascites). All of them had undergone clinical, laboratory, and imaging investigations and were treated as per standard of care. All patients underwent abdominal paracentesis, and fluid samples were sent for analysis.

STATISTICAL ANALYSIS USED

ANOVA, Kruskal-Wallis H test, and ROC curve analysis.

RESULTS

Among the gradients, only SAPG and SAAG had over all statistical significance (<0.005) among the groups, but no significance between malignancy and tubercular peritonitis had been observed. Similarly all the ascitic fluid parameters measured had an overall statistical significance (<0.005), but there was no significant difference observed between malignancy and tubercular peritonitis groups. However, ascitic fluid and serum HDL cholesterol had a statistical significance (<0.05) between malignancy and tubercular peritonitis.

CONCLUSIONS

With a cut-off value of 4, SAPG is one of best screening tests in differentiation of cirrhotic with noncirrhotic ascites when compared with SAAG, whereas it is a poor parameter with high sensitivity and very low specificity in differentiation of malignant with nonmalignant ascites. Also the present study reveals HDL cholesterol levels in ascitic fluid to be a valuable marker with higher sensitivity and specificity in differentiation of malignancy and tuberculosis peritonitis (i.e., differentiation of low SAAG ascites).

The patient with refractory ascites

Refractory ascites indicates advanced chronic liver disease and represents a therapeutic challenge. It may be triggered by spontaneous bacterial peritonitis and denotes poor prognosis. While liver transplantation is the ultimate treatment, for the relief of ascites therapeutic paracentesis with iv-administration of albumin and/or transjugular intrahepatic portosystemic shunt (TIPS) are well established. With rapid deterioration of renal function patients can develop hepatorenal syndrome. There is increasing evidence that these patients can be bridged to transplantation with vasopressin analogs (terlipressin) and albumin.

Accumulation of Selected Carotenoids, α-Tocopherol and Retinol in Human Ovarian Carcinoma Ascitic Fluid

BACKGROUND

Patients with severe forms of cancer are reported to have reduced concentrations of micronutrients in plasma due to the chronic reduction of food intake and an increased metabolism of these components. The purpose of this study was to evaluate if an accumulation of carotenoids, alpha-tocopherol and retinol in malignant ascitic fluid in women with ovarian cancer might contribute to a loss of these components from plasma.

METHODS

Blood and ascitic fluid samples obtained from 21 women with ovarian carcinomas and 17 healthy controls were analyzed for retinol, retinol-binding protein (RBP), alpha-tocopherol and carotenoids.

RESULTS

Plasma concentrations of all micronutrients were lower in cancer patients compared to controls. Ascitic fluid concentration of all investigated components was comparable (73-110%) to plasma. While the mean concentration of retinol in malignant ascites represented 73% of that in plasma, the concentration of RBP was less than 10% resulting in an increased mean molar ratio of retinol to RBP from 1.18 to 10.5.

CONCLUSIONS

The results suggest that lower plasma concentrations of micronutrients in women suffering from ovarian carcinoma are not only caused by a cachexia-induced decrease of food intake and a higher rate of metabolic utilization, but also by a substantial yet not considered transfer from plasma into ascitic fluid possibly associated with plasma lipoproteins. This raises questions with regard to the protective function of these plasma components in ascitic fluid, the consequences of paracentesis on an additional supplementation and finally the possibility to use one or a combination of these components as an additional marker to discriminate between benign and malignant ascites.

Markedly elevated levels of vascular endothelial growth factor in malignant ascites

BACKGROUND

Vascular endothelial growth factor (VEGF) is a potent angiogenic factor that also has the ability to increase vascular permeability. Malignant ascites has significant morbidity, but the mechanism of its development is unknown. Because of the permeability-inducing properties of VEGF, we hypothesized that malignant ascites formation is associated with high levels of VEGF. The purpose of our study was to determine the role of VEGF in malignant ascites formation.

METHODS

Ascites from 25 patients with gastric (n = 6), colon (n = 7), or ovarian (n = 12) cancers was collected by paracentesis or surgery. VEGF protein levels were determined by enzyme-linked immunosorbent assay. The effect of ascites on endothelial cell permeability was assessed by evaluating propidium iodide uptake by human umbilical vein endothelial cells (HUVECs) exposed to ascites. Neutralizing antibodies to VEGF added to ascites were used to determine the causal effect of VEGF in permeability induction.

RESULTS

VEGF protein levels were markedly increased in malignant ascites compared with levels in nonmalignant cirrhotic ascites (controls). VEGF protein levels in ovarian, gastric, and colon cancer ascites were found to be increased 45, 23, and 12 times, respectively, compared with levels in cirrhotic ascites. Malignant ascites from patients with colon and gastric cancer caused an increase in permeability in HUVECs in all cases. Neutralizing VEGF activity in colon cancer ascites decreased in-vitro HUVEC permeability in three of four cases.

CONCLUSIONS

VEGF protein levels are markedly elevated in malignant ascites. VEGF may play a role in malignant ascites formation by increasing endothelial cell permeability.

Multivariate discriminant analysis of biochemical parameters for the differentiation of clinically confounding liver diseases

We describe a series of studies on the contribution of laboratory medicine to the differential diagnosis of clinically confounding diseases in the field of chronic hepatobiliary diseases. Ascitic cholesterol and lactate dehydrogenase (LD), selected by multivariate discriminant analysis (MDA) from a multitude of serum and ascitic analytes, correctly classified 100% of patients with malignant ascites or non-malignant ascites. In addition, ascitic pseudouridine differentiated hepatocarcinoma (HC) from cirrhotic ascites with a diagnostic effectiveness (overall discrimination power) of 90%. A panel of analytes constituted by serum gamma-glutamyltransferase (GGT), the GGT isoenzyme complexed with low- and very low-density lipoprotein, aspartate aminotransferase, copper, hepatic alkaline phosphatase (AP), the LD-5 isoenzyme and alpha-fetoprotein (AFP), selected by the MDA, correctly classified 93% of about 200 cases of cirrhosis or HC. Finally, MDA also identified an equation, based on serum values of the LD-4/LD-5 and carcinoembryonic antigen/AFP ratios, AP and iron that correctly classified 96% of HC or secondary liver neoplasia cases in 100 patients. This approach based on panels of analytes selected by a sophisticated statistical analysis is a rapid and non-invasive contribution to the differential diagnosis of chronic liver disease including neoplasia.

Free fatty acid analysis in ascitic fluid improves diagnosis in malignant abdominal tumors

The fasting concentration of free fatty acids (FFA) in the ascitic fluid was determined in 14 patients with malignant ascites and in 19 patients with liver cirrhosis. In malignant ascites FFA levels were increased more than three times when compared with the levels in cirrhotic ascites (5.241 +/- 0.493 vs. 1.558 +/- 0.170 mumol/ml; P < 0.0001). Palmitic acid was the most representative saturated FFA (which together accounted for 2.499 +/- 0.323 vs. 0.833 +/- 0.064 mumol/ml; P < 0.0001), while unsaturated FFA (2.741 +/- 0.298 vs. 0.725 +/- 0.111 mumol/ml; P < 0.001) were represented, in decreasing order, by oleic, linoleic and arachidonic acids. The ratio of unsaturated to saturated FFA was higher in neoplastic patients (1.35 +/- 0.29 vs. 0.826 +/- 0.065 P < 0.05). Albumin concentration in ascitic fluid of neoplastic patients was 22.44 +/- 1.35 g/l, while that of cirrhotic patients was 8.19 +/- 0.32 g/l, P < 0.0001. A close relationship (R2 = 95.14%) between albumin concentration in ascitic fluid and levels of total FFA was found. These data support the hypothesis that the elevation of FFA in ascitic fluid allows discrimination between malignant and non-malignant ascites.

Composition of ascitic fluid in liver cirrhosis: bile acid and lipid content

The concentrations of lipids, bile acids and proteins were evaluated in the ascitic fluid and plasma of 23 cirrhotics. Ascitic fluid density was highly correlated with its protein content, represented mostly by low molecular weight proteins. The ratio of plasma to ascitic fluid concentrations of nine examined proteins increased with molecular weight, indicating a selective ultrafiltration of the peritoneal transudate. Low density lipoproteins in ascitic fluid had modified electrophoretic mobility. Total cholesterol had a higher plasma to ascitic fluid ratio than high density lipoprotein cholesterol, whereas bile acids and proteins had similar plasma to ascitic fluid ratios. Indeed, bile acids strongly bind to circulating albumin: consequently ascitic fluid contains more cholic acid (less hydrophobic) than other bile acids. Analysis of both plasma and ascitic fluid composition in cirrhotics provides useful information on processes regulating passage of blood components into the peritoneal cavity.