Regulating effect of Chinese herbal medicine on the peritoneal lymphatic stomata in enhancing ascites absorption of experimental hepatofibrotic mice

Recent advances in the research of lymphatic stomata

Lymphatic stomata are small openings of lymphatic capillaries on the free surface of the mesothelium. The peritoneal cavity, pleural cavity, and pericardial cavity are connected with lymphatic system via these small openings, which have the function of active absorption. The ultrastructure of the lymphatic stomata and their absorption from the body cavities are important clinically, such as ascites elimination, neoplasm metastasis, and inflammatory reaction. The lymphatic stomata play an important role in the physiological and pathological conditions. Our previous study indicated for the first time that nitric oxide (NO) could regulate the opening and absorption of the lymphatic stomata. It could decrease the level of free intracellular calcium [Ca(2+)] through increasing the cyclic guanosine monophosphate (cGMP) level in the rat peritoneal mesothelial cells, thus regulating the lymphatic stomata. This process is related with the NO-cGMP-[Ca(2+)] signal pathway. In this review, we summarize the recent advances in understanding the development and the function of the lymphatic stomata. The ultrastructure and regulations of the lymphatic stomata are also discussed in this review.

Cell signal transduction mechanism for nitric oxide regulating lymphatic stomata and its draining capability

We have previously demonstrated that nitric oxide (NO) is involved in the regulation of the lymphatic stomata. However, the related mechanisms are still unknown. The present study was designed to test the hypothesis that NO-cyclic guanosine monophosphate (cGMP) -mediated cytosolic Ca(2+) concentration ([Ca(2+)]i) signaling may contribute to the regulation of the lymphatic stomata and lymph drainage. Using trypan blue as a tracer, the effects of NO-cGMP-Ca(2+) signal cascade on the lymphatic stomata and lymph absorption were examined by means of scanning electron microscopy. Then, the role of NO in cGMP and [Ca(2+)]i of rat peritoneal mesothelial cells (RPMCs) was measured by radioimmunoassay and a confocal laser scanning microscope. Our results showed that NO-donor spermine/nitric oxide complex (Sper/NO) could broaden the opening area of the lymphatic stomata and enhance lymph absorption in a dose-dependent manner. These NO-mediated changes could be blocked by 1H-[1,2,4] oxadiazolo [4,3-a] quinoxalin-1-one (ODQ), a specific inhibitor of soluble guanylyl cyclase, and mimicked by calcium channel blocker nifedipine. Furthermore, Sper/NO enhanced the cGMP level and lessened [Ca(2+)](i) in RPMCs, which was completely abrogated at the presence of ODQ. Nifedipine induced an immediate and marked decrease of [Ca(2+)](i) in the RPMCs, which was not attenuated by addition of Sper/NO, indicating that the Sper/NO-cGMP signaling system induced [Ca(2+)](i) change was related to the L-type voltage-gated calcium channel in the RPMCs. Our results suggest that NO enlarges the opening area of the lymphatic stomata to strengthen the lymph drainage of tracer by means of NO-cGMP-[Ca(2+)]i signal transduction pathway in the RPMCs.

Effects of Chinese traditional compound, JinSanE, on expression of TGF-β1 and TGF-β1 type II receptor mRNA, Smad3 and Smad7 on experimental hepatic fibrosis in vivo

AIM: The transforming growth factor-beta (TGF-β)/Smad signaling pathway system plays a prominent role in the control of cell growth and extracellular matrix formation in the progression of liver fibrogenesis. Smad proteins can either positively or negatively regulate TGF-β responses. In this study, the therapeutic effects of Chinese traditional compound decoction, JinSanE, and the changes of TGF-β/Smad signaling pathway system in carbon tetrachloride (CCl₄)-induced rat experimental liver fibrosis were examined.

METHODS: Seventy-two healthy Wistar rats were assigned to groups including normal control group, CCl₄ model group, JinSanE treatment group I and JinSanE treatment group II. Each group contained 18 rats. All groups, except the normal control group, received CCl₄ subcutaneous injection for 8 wk. Rats in JinSanE groups I and II were orally treated with JinSanE daily at the 1^st and 5^th wk, respectively, after exposure to CCl₄. The expression of TGF-β1 and TGF-β1 type II receptor (TRII) mRNA in the liver was determined by reverse transcription polymerase chain reaction, and the expression of TGF-β1, Smad3 and Smad7 by immunohistochemistry. The liver histopathology was also examined by HE staining and observed under electron microscope. The activities of several serum fibrosis-associated enzymes, alanine aminotransferase (ALT), aspartate aminotransferase (AST), the levels of serum hyaluronic acid (HA) were assayed.

RESULTS: Hepatic fibrosis caused by CCl₄ was significantly inhibited in the JinSanE-treated groups. The degrees of necrosis/degeneration and fibrosis scores were significantly lower in the JinSanE-treated groups than in the model control group. The expression of TGF-β1, TRII and Smad3 was significantly higher in the model group than that in the JinSanE-treated groups, and the active/total TGF-β1 ratio in the JinSanE groups was suppressed. Expression of TRII mRNA and Smad3 proteins showed a distribution pattern similar to that of TGF-β1 with a direct correlation in terms of the degree of hepatic fibrosis. The amount of positive staining Smad7 cells was significantly less in the model group than in the JinSanE-treated groups and the normal group. The contents of ALT, AST and HA were significantly lower in the JinSanE-treated groups than those in the model group.

CONCLUSION: Traditional Chinese medicine, JinSanE, prevents the progression of hepatic damage and fibrosis through the inhibition of TGF-β1, TRII and Smad3 signal proteins, and increases expression of Smad7 signal protein in vivo.

Impact of cirrhosis on the development of experimental hepatic metastases by B16F1 melanoma cells in C57BL/6 mice

Metastases rarely occur in human livers with cirrhosis in clinical studies. We postulated that this phenomenon would also occur in experimental cirrhosis. Cirrhosis was established in C57BL/6 mice by carbon tetrachloride (CCl(4)) gastrogavage. B16F1 melanoma cells were injected into the mesenteric vein to induce hepatic metastases. Contrary to our postulate, there was greater than 4-fold increase in metastasis in animals with cirrhosis compared to controls. Intravital videomicroscopy showed that the hepatic sinusoids were narrower and more tumor cells were retained in the terminal portal vein (TPV) in cirrhotic livers. Immunohistochemistry demonstrated that the expression of vascular adhesion molecules was significantly increased in cirrhosis. Using confocal microscopy and the fluorescent nitric oxide (NO) probe 4,5-diaminofluorescein diacetate, a significantly lower level of NO release was detected in livers with cirrhosis both in basal conditions and after tumor cell arrest. Eight hours after mesenteric vein tumor cell injection, the percentage of apoptotic tumor cells in the sinusoids was 17% +/- 2% in livers with cirrhosis and 30% +/- 5% in normal livers. More mitotic and Ki-67 labeled tumor cells were seen in livers with cirrhosis. In conclusion, the changes in architecture and adhesion molecule expression in livers with cirrhosis may cause more tumor cells to arrest in the TPV. Lower levels of NO production may reduce apoptosis of B16F1 cells in livers with cirrhosis. As a result, these changes may promote the growth of metastasis in this cirrhotic model.

Experimental study of effect of Ganyanping on fibrosis in rat livers

AIM: To observe the effects of Ganyanping on CCl₄-induced hepatic fibrosis in rats.

METHODS: The rats were separated randomly into five groups. Groups A to group D, each consisting of 15 rats, were for different tests, while 8 rats were used as normal controls (N). For group D, CCl₄ was injected subcutaneously, at a dosage of 3 mL/kg for 9 wk. For group A, Ganyanping was administered via gastric tube at a dosage of 10 mL/kg. For group B, the treatment with Ganyanping was started 4 wk after CCl₄ administration. In group C, Ganyanping was administered 8 wk after the intoxication, and treatment lasted for 4 wk. Liver tissues were fixed in 10% formalin and embedded in paraffin. Pathologic changes, particularly fibrosis, were evaluated on the HE and V-G-stained sections. Ten middle-power fields were randomly selected for assessment of collagen deposition.

RESULTS: Loss of normal hepatic architecture, some with pseudo-lobule formation, was observed in group D, while hepatocytes steatosis and fibrosis were less pronounced in the animals treated with Ganyanping. Pseudo-lobule formation was not evident in the latter groups. The total collagen area and ratio were 840.23 ± 81.65 and 7.0 ± 0.9, respectively in group D, the ratio being reduced greatly in the Ganyanping-treated groups (148.73 ± 45.89 and 1.16 ± 0.33, respectively). The activities of MAO and ACP were elevated and that of SDH in group D decreased in the hepatic tissue as compared to the control group. The treatment with Ganyanping abrogated these enzymatic changes.

CONCLUSION: Our data approved that Ganyanping could improve the microcirculation in the liver, reduce oxygen-derived free radicals, and enhance the cellular metabolism and immune function, all resulting in an anti-fibrotic effect. Hence, Ganyanping can protect the liver from fibrosis. It may be a safe and effective preparation for patient with fibrosis.

Preparation and identification of anti-transforming growth factor β1 U1 small nuclear RNA chimeric ribozyme in vitro

AIM: To study the preparation and cleavage activity of anti-transforming growth factor (TGF)β1 U1 small nuclear (sn) RNA chimeric hammerhead ribozymes in vitro.

METHODS: TGFβ1 partial gene fragment was cloned into T-vector at the downstream of T7 promoter. ³²p-labeled TGFβ1 partial transcripts as target RNA were transcribed in vitro and purified by denaturing polyacrylamide gel electrophoresis (PAGE). Anti-TGFβ1 ribozymes were designed by computer, then synthetic ribozyme fragments were cloned into the U1 ribozyme vector pZeoU1EcoSpe containing U1 snRNA promoter/enhancer and terminator. ³²p-labeled U1 snRNA chimeric ribozyme transcripts were gel-purified, incubated with target-RNAs at different conditions and autoradiographed after running denaturing PAGE.

RESULTS: Active U1snRNA chimeric ribozyme (U1Rz803) had the best cleavage activity at 50 °C; at 37 °C, it was active, K_m = 34.48 nmol/L, K_cat = 0.14 min^-1; while the point mutant ribozyme U1Rz803_m had no cleavage activity, so these indicated the design of U1Rz803 was correct.

CONCLUSION: U1Rz803 prepared in this study possessed the perfect specific catalytic cleavage activity. These results indicate U1 snRNA chimeric ribozyme U1Rz803 may suppress the expression of TGFβ1 in vivo, therefore it may provide a new avenue for the treatment of liver fibrosis in the future.