Endothelin-1 derived from spleen-activated Rho-kinase pathway in rats with secondary biliary cirrhosis

Endothelin receptor B enhances liver injury and pro-inflammatory responses by increasing G-protein-coupled receptor kinase-2 expression in primary biliary cholangitis

Severe diseases like cirrhosis and liver failure can be developed from primary biliary cholangitis (PBC). Endothelin-2 (EDN2) and endothelin receptor B (EDNRB) are related to the pathogenesis of PBC. However, the roles of EDN2 and EDNRB in PBC-related liver injury and inflammation along with molecular mechanisms are poorly defined. In this study, histopathologic alterations of liver tissues were assessed through hematoxylin-eosin staining. Alanine transaminase (ALT), alkaline phosphatase (ALP), aspartate transaminase (AST), and γ-Glutamyltranspetidase (GGT) (4 liver function indexes) serum levels were detected with corresponding activity assay kits. Also, we determined the levels of M2 subtype anti-mitochondrial antibody (AMA-M2), interferon-gamma (IFN-γ), and tumor-necrosis factor alpha (TNFα) in serum with ELISA assay. Later, RT-qPCR assay was used to measure the expression of genes at mRNA levels, while western blotting and immunohistochemical techniques were used to detect protein levels of genes. Our results showed that the liver tissues of PBC patients and mice presented with severe hepatocyte injury and inflammatory cell infiltration as well as destruction of intrahepatic small bile ducts. ALP, AST, ALT, GGT, AMA-M2, IFN-γ, and TNF-α serum levels were higher in PBC patients and mice. Besides, EDN2 and EDNRB were highly expressed in serums and livers of PBC patients and mice. EDNRB potentiated PBC-related liver injury and pro-inflammatory responses, as evidenced by observation of serious liver pathologic injury and increased serum levels of ALP, AST, ALT, AMA-M2, IFN-γ, and TNF-α in PBC mice following EDNRB overexpression. EDNRB overexpression or activation via its agonist IRL-1620 TFA triggered liver injury and pro-inflammatory responses, increased GRK2 expression and induced NF-κB expression and activation in wild-type mice. EDNRB knockdown or inhibition by Bosentan alleviated liver damage and inflammation, reduced GRK2 expression, and inhibited NF-κB in PBC mice. These findings suggested EDNRB loss or inhibition weakened liver injury and pro-inflammatory responses by down-regulating GRK2 and inhibiting the NF-κB pathway in PBC mice.

Small-For-Size Syndrome and Graft Inflow Modulation Techniques in Liver Transplantation

BACKGROUND

Partial liver transplantation has recently been proposed to alleviate organ shortages. However, transplantation of a small-for-size graft is associated with an increased risk of posttransplant hepatic dysfunction, commonly referred to as small-for-size syndrome (SFSS). This review describes the etiology, pathological features, clinical manifestations, and diagnostic criteria of SFSS. Moreover, we summarize strategies to improve graft function, focusing on graft inflow modulation techniques. Finally, unmet needs and future perspectives are discussed.

SUMMARY

In fact, posttransplant SFSS can be attributed to various factors such as preoperative status of the recipients, surgical techniques, donor age, and graft quality, except for graft size. With targeted improvement measures, satisfactory clinical outcomes can be achieved in recipients at increased risk of SFSS. Given the critical role of relative portal hyperperfusion in the pathogenesis of SFSS, various pharmacological and surgical treatments have been established to reduce or partially divert excessive portal inflow, and recipients will benefit from individualized therapeutic regimens after careful evaluation of benefits against potential risks. However, there remain unmet needs for further research into different aspects of SFSS to better understand the correlation between portal hemodynamics and patient outcomes.

KEY MESSAGES

Contemporary transplant surgeons should consider various donor and recipient factors and develop case-specific prevention and treatment strategies to improve graft and recipient survival rates.

Splenectomy ameliorates portal pressure and anemia in animal models of cirrhotic and non-cirrhotic portal hypertension

PURPOSE

Portal hypertension (PH)-associated splenomegaly is caused by portal venous congestion and splanchnic hyperemia. This can trigger hypersplenism, which favors the development of cytopenia. We investigated the time-dependent impact of splenectomy on portal pressure and blood cell counts in animal models of non-cirrhotic and cirrhotic PH.

MATERIALS AND METHODS

Ninety-six rats underwent either partial portal vein ligation (PPVL), bile duct ligation (BDL), or sham operation (SO), with subgroups undergoing additional splenectomy. Portal pressure, mean arterial pressure, heart rate, blood cell counts and hemoglobin concentrations were evaluated throughout 5 weeks following surgery.

RESULTS

Following PPVL or BDL surgery, the animals presented a progressive rise in portal pressure, paralleled by decreased mean arterial pressure and accelerated heart rate. Splenectomy curbed the development of PH in both models (PPVL: 16.25 vs. 17.93 ​mmHg, p ​= ​0.083; BDL: 13.55 vs. 15.23 ​mmHg, p ​= ​0.028), increased mean arterial pressure (PPVL: +7%; BDL: +9%), and reduced heart rate (PPVL: -10%; BDL: -13%). Accordingly, splenectomized rats had lower von Willebrand factor plasma levels (PPVL: -22%; BDL: -25%). Splenectomy resulted in higher hemoglobin levels in PPVL (14.15 vs. 13.08 ​g/dL, p ​< ​0.001) and BDL (13.20 vs. 12.39 ​g/dL, p ​= ​0.097) animals, and significantly increased mean corpuscular hemoglobin concentrations (PPVL: +9%; BDL: +15%). Thrombocytopenia only developed in the PPVL model and was alleviated in the splenectomized subgroup. Conversely, BDL rats presented with thrombocytosis, which was not affected by splenectomy.

CONCLUSIONS

Splenectomy improves both cirrhotic and non-cirrhotic PH, and ameliorates the hyperdynamic circulation. Hypersplenism related anemia and thrombocytopenia were only significantly improved in the non-cirrhotic PH model.

Endothelin receptors promote schistosomiasis-induced hepatic fibrosis via splenic B cells

Endothelin receptors (ETRs) are activated by vasoactive peptide endothelins and involved in the pathogenesis of hepatic fibrosis. However, less is known about the role of ETRs in Schistosoma (S.) japonicum-induced hepatic fibrosis. Here, we show that the expression of ETRs is markedly enhanced in the liver and spleen tissues of patients with schistosome-induced fibrosis, as well as in murine models. Additional analyses have indicated that the expression levels of ETRs in schistosomiasis patients are highly correlated with the portal vein and spleen thickness diameter, both of which represent the severity of fibrosis. Splenomegaly is a characteristic symptom of schistosome infection, and splenic abnormality may promote the progression of hepatic fibrosis. We further demonstrate that elevated levels of ETRs are predominantly expressed on splenic B cells in spleen tissues during infection. Importantly, using a well-studied model of human schistosomiasis, we demonstrate that endothelin receptor antagonists can partially reverse schistosome-induced hepatic fibrosis by suppressing the activation of splenic B cells characterized by interleukin-10 (IL-10) secretion and regulatory T (Treg) cell-inducing capacity. Our study provides insights into the mechanisms by which ETRs regulate schistosomiasis hepatic fibrosis and highlights the potential of endothelin receptor antagonist as a therapeutic intervention for fibrotic diseases.

Schistosomiasis is a serious but neglected tropical infectious disease. which can lead to hepatic fibrosis and death. To date, there are still no approved antifibrotic therapies. Hepatic fibrosis results in portal hypertension and variceal bleeding, and it is the primary cause of mortality from schistosomiasis. Splenomegaly and hypersplenism can manifest following the development of portal hypertension. Accumulating evidence suggests that the spleen plays a critical role in the development of hepatic fibrosis. In this study, using Schistosoma (S.) japonicum in both humans and mice, we show that progressive hepatic schistosomiasis caused elevation of endothelin receptors (ETRs) both in liver and spleen tissues, and the endothelin receptor-producing cells are mainly located in splenic B cells. More importantly, we demonstrate that endothelin receptor antagonists can partially reverse schistosome-induced hepatic fibrosis by suppressing the activation of splenic B cells during infection. Thus, our study highlights the potential of endothelin receptor antagonist as a therapeutic intervention for schistosomiasis and other fibrotic diseases.

Small-for-size graft, small-for-size syndrome and inflow modulation in living donor liver transplantation

The extended application of living donor liver transplantation (LDLT) has revealed the problem of graft size mismatching called "small-for-size syndrome (SFSS)." The initial trials to resolve this problem involved increasing the procured graft size, from left to right, and even extending to include a right lobe graft. Clinical cases of living right lobe donations have been reported since then, drawing attention to the risks of increasing the liver volume procured from a living donor. However, not only other modes of increasing graft volume (GV) such as auxiliary or dual liver transplantation, but also control of the increased portal pressure caused by a small-for-size graft (SFSG), such as a porto-systemic shunt or splenectomy and optimal outflow reconstruction, have been trialed with some positive results. To establish an effective strategy for transplanting SFSG and preventing SFSS, it is essential to have precise knowledge and tactics to evaluate graft quality and GV, when performing these LDLTs with portal pressure control and good venous outflow. Thus, we reviewed the updated literature on the pathogenesis of and strategies for using SFSG.

Conceptual changes in small-for-size graft and small-for-size syndrome in living donor liver transplantation

Early series in living donor liver transplantation (LDLT) in adults demonstrated a lower safe limit of graft volume standard liver volume ratio 25%–45%. A subsequent worldwide large LDLT series proposed a 0.8 graft recipient weight ratio (GRWR) to define small-for-size graft (SFSG) in adult LDLT. Thereafter, researchers identified innate and inevitable factors including changes in liver volume during imaging studies and graft shrinkage due to perfusion solution. Although the definition of small-for-size syndrome (SFSS) advocated in the 2000s was mainly based on prolonged cholestasis and ascites output, the term SFSS was inadequate to describe clinical manifestations possibly caused by multiple factors. Thus, the term “early allograft dysfunction (EAD),” characterized by total bilirubin >10 mg/dL or coagulopathy with international normalized ratio >1.6 on day 7, has become prevalent to describe graft dysfunction including SFSS after LDLT. Although various efforts have been made to overcome EAD in LDLT, graft selection to maintain an expected GRWR >0.8 and full venous drainage, as well as inflow modulation using splenic artery ligation, have become standard in recent LDLT.

Spleen Regulates Hematopoietic Stem/Progenitor Cell Functions Through Regulation of EGF in Cirrhotic Hypersplenism

BACKGROUND

Hematopoietic abnormality is a common cause of cirrhotic hypersplenism (CH) complications and death; it causes serious adverse effects and is associated with bleeding, anemia, infection in CH patients. However, the underlying mechanism is unclear.

AIMS

We aimed to investigate the effects of the spleen on hematopoiesis and hematopoietic stem/progenitor cells (HSPCs) in CH patients.

METHODS

Eleven CH patients were enrolled to assess the effects of the spleen on HSPC functions. Hematopoietic changes were examined by flow cytometry analysis. HSPC functions were detected with colony-forming assays and in vitro cell cultures. Enzyme-linked immunosorbent assay (ELISA) was used to test the concentration of epithelial growth factor (EGF).

RESULTS

The number of HSPCs was decreased in CH patients and was rescued after splenectomy. Serum from CH patients dysregulated HSPCs function, and serum from splenectomy patients restored the dysregulated HSPC function in vitro. The concentration of EGF was decreased in CH patients and was restored to normal level after splenectomy. EGF rescued the dysregulated HSPCs function in vitro.

CONCLUSIONS

The spleen can regulate the functions of HSPCs in CH patients by regulating EGF signaling. EGF may be a therapeutic target for CH treatment.

Up-regulated expression of PTEN after splenetomy may prevent the progression of liver fibrosis in rats

BACKGROUND/PURPOSE

To investigate the mechanisms of delaying progression of liver fibrosis by splenectomy.

METHODS

Liver fibrosis was induced by common bile duct ligation. Rats were divided into 3 groups randomly: group A with common bile duct ligation and splenectomy (n = 45), group B with common bile duct ligation and spleen sham operation (n = 45), group C with sham common bile duct ligation and spleen sham operation (n = 45). Liver samples were collected at the 1st, 3rd and 5th week. H&E staining and Sirius staining were used to evaluate the degree of liver fibrosis, immunohistochemical staining was used to measure the expression of α-SMA and PTEN. PTEN mRNA and protein expression was measured by real-time PCR and Western-blot.

RESULTS

Over time, liver fibrosis developed gradually in group A and B. The expression of PTEN mRNA and protein in group A was higher than that in group B (P < 0.05), while the expression of α-SMA was higher in group B (P < 0.05). The expression of PTEN was negatively correlated with α-SMA (r = -0.86, P < 0.05).

CONCLUSIONS

In this study, splenectomy can up-regulate the expression of PTEN and reduce the secretion of α-SMA, thereby deterring the progression of liver fibrosis.

Sodium ferulate lowers portal pressure in rats with secondary biliary cirrhosis through the RhoA/Rho-kinase signaling pathway: a preliminary study

Cirrhotic rats show higher expression levels of hepatic RhoA and Rho-kinase than normal healthy rats, and the activation of this signaling pathway leads to portal hypertension. Sodium ferulate (SF) has been shown to decrease the production of geranylgeranyl pyrophosphate (GGPP), a substance essential for RhoA activation. In the present study, to investigate the effects of SF on fibrosis, portal hypertension and the RhoA/Rho-kinase pathway, hepatic cirrhosis was induced in rats by bile duct ligation. Liver function and fibrogenesis-related biochemical parameters, the hepatic hydroxyproline content, the pathological characteristics of the liver sections and the levels of hepatic α-smooth muscle actin (α-SMA; by immunohistochemistry) were analyzed to assess effects of SF on hepatic fibrosis. In addition, hepatic RhoA, Rho-kinase and endothelial nitric oxide synthase (eNOS) expression was examined by immunohistochemistry. Apoptosis in the SF-treated and SF + GGPP-treated rat primary hepatic stellate cells (HSCs) and a human stellate cell line (LX-2) was examined by flow cytometry. Intrahepatic resistance and responsiveness to the α1-adrenoceptor agonist, methoxamine, were investigated by in situ liver perfusion. Treatment with SF did not affect fibrosis-related biochemical parameters or the hydroxyproline content; however, SF reduced the histological evidence of fibrosis and hepatocyte damage. The SF-treated rats had a significantly lower expression of α-SMA and Rho-kinase, as well as an increased hepatic eNOS content; however, SF did not affect RhoA expression. The SF-treated HSCs had a significantly increased apoptotic rate compared to the untreated rats. Following the addition of GGPP, the rate apoptotic rate decreased. SF reduced basal intrahepatic resistance and the responsiveness of hepatic vascular smooth muscle to methoxamine. Therefore, our data demonstrate that SF reduces fibrogenesis, decreases portal pressure in cirrhotic rats and inhibits the activation of the RhoA/Rho-kinase signaling pathway.

Ultrasonic diagnosis and vasoactive substances examination in patients with cirrhosis

OBJECTIVE

To investigate hemodynamic change of patients with cirrhosis by using Color Doppler ultrasound technique and to explore the significance of change in the content of vasoactive substances-plasma endothelin-1 (ET-1) and calcitonin gene-related peptide (CGRP).

METHODS

A total of 178 cases with cirrhosis were regarded as study groups, and were divided into three degrees: A, B and C according to child-pugh and meanwhile 60 cases were regarded as normal control group. Portal vein and splenic vein of patients were explored by adopting Color Doppler ultrasound technique, related indexes were recorded and the blood flow as well as their ration in the two groups was calculated. Radio immunoassay was adopted to detect the content of plasma ET-1 and CGRP in both study group and contrast group.

RESULTS

Compared with the healthy cases in the contrast group, there was abnormal hemodynamics in the system of portal vein of patients with cirrhosis and the content of plasma ET-1 and CGRP was increased obviously. In the Child-Pugh liver function grades, the content of ET-1 and CGRP was increased as the degree of cirrhosis became more and more serious. There was no significant difference in the comparison between those without ascites and those in contrast group (P>0.05), the content of plasma ET-1 and CGRP in patients without ascites was increased remarkably. Besides, there was positive correlation between the content of plasma ET-1 and CGRP and Dpv, Dsv and Qsv.

CONCLUSION

Detection of abnormal hemodynamics of portal vein and splenic vein by Color Doppler ultrasound technique can be one of the means for diagnosis of hypertension. Plasma ET-1 and CGRP of patients with cirrhosis reflect the serious degree of the damage in live function and play an important role in the formation and development of portal hypertension.

Heme oxygenase/carbon monoxide pathway inhibition plays a role in ameliorating fibrosis following splenectomy

Splenectomy is a recognized therapy for liver cirrhosis with splenomegaly, since it decreases free iron concentration that accompanies the destruction of red blood cells. Heme oxygenase (HO)-1 and its by-products, iron and carbon monoxide (CO), play crucial roles in hepatic fibrosis. The aim of the present study was to determine whether splenectomy in cirrhotic rats induced by bile duct ligation (BDL), through the HO/CO pathway, could slow down the development of liver fibrosis. Male Sprague-Dawley rats were divided randomly into the sham, BDL, splenectomy, Fe, zinc protoporphyrin (Znpp) and cobalt protoporphyrin (Copp) treatment groups, for inhibiting and inducing HO-1 expression. The level of HO-1 was detected by western blot analysis and reverse transcription-polymerase chain reaction. Serum carboxyhemoglobin (COHb), iron and portal vein pressure (PVP) were also quantified. Liver iron was measured by atomic absorption spectrometry with acetylene-air flame atomization. HO-1 and α-smooth muscle actin (α-SMA) were localized by immunohistochemistry. Liver and spleen iron were visualized by Perls' Prussian blue staining. Hepatic fibrosis was assessed using hematoxylin and eosin (H&E) staining. Enzyme-linked immunosorbent assay (ELISA) was used to detect serum transforming growth factor-β1 (TGF-β1). The results showed that liver, spleen and serum levels of HO-1, COHb and iron were greatly enhanced in the BDL group compared with the sham group; they were reduced following splenectomy and Znpp treatment, but were elevated in the Copp and Fe groups. Hydroxyproline, TGF-β1, α-SMA, PVP and malonaldehyde levels were lower in the splenectomy and Znpp groups compared to BDL, while higher levels were observed in the Copp and Fe-treated groups. Our study shows that splenectomy reduces iron and CO levels in part by reducing HO-1 expression, and it decreases portal pressure and slightly decreases hepatic fibroproliferation.

Strategies for successful left-lobe living donor liver transplantation in 250 consecutive adult cases in a single center

BACKGROUND

Living donor liver transplantation (LDLT) using left-lobe grafts was not generally recognized as feasible due to the problem of graft size.

STUDY DESIGN

We retrospectively evaluated strategies for successful left-lobe LDLT in 250 consecutive cases stratified into 2 eras: Era 1 (n = 121), in which surgical procedures were continually refined, and Era 2 (n = 129), in which established procedures were used.

RESULTS

Graft volume (GV) did not affect the incidence of graft function or survival. Era 2 patients had decreased portal vein (PV) pressure at closure (16.0 ± 3.5 mmHg vs 19.1 ± 4.6 mmHg, p < 0.01), increased PV flow/GV (301 ± 125 mL/min/100g vs 391 ± 142 mL/min/100g, p < 0.01), and improved graft survival rate (1-year: 90.6% vs 81.8%. p < 0.01) despite the smaller GV/standard volume (SLV) ratio (36.2% ± 5.2% vs 41.2% ± 8.8%, p < 0.01) compared with Era 1. Patients in Era 2 had lower PV pressure and greater PV flow (y = 598-5.7 x, p = 0.02) at any GV/SLV compared with cases in Era 1 (y = 480-4.3 x, p < 0.01), representing greater graft compliance. Univariate analysis for graft survival showed that Era 1, Model for End-Stage Liver Disease (MELD) score ≥ 20, inpatient status, closing portal venous pressure ≥ 20 mmHg, no splenectomy, and operative blood loss ≥ 10 L were the risk factors for graft loss, and multivariate analysis showed that Era 1 was the only significant factor (p < 0.01). During Era 2, development of primary graft dysfunction was associated with inpatient recipient status (p = 0.02) and donor age ≥ 45 years (p < 0.01).

CONCLUSIONS

The outcomes of left-lobe LDLT were improved by accumulated experience and technical developments.