Hepatopulmonary syndrome is associated with low sphingosine-1-phosphate levels and can be ameliorated by the functional agonist fingolimod.

BACKGROUND & AIMS: Hepatopulmonary syndrome (HPS) is characterised by a defect in arterial oxygenation induced by pulmonary vascular dilatation in patients with liver disease. Fingolimod, a sphingosine-1-phosphate (S1P) receptor modulator, suppresses vasodilation by reducing nitric oxide (NO) production. We investigated the role of S1P in patients with HPS and the role of fingolimod as a therapeutic option in an experimental model of HPS. METHODS: Patients with cirrhosis with HPS (n = 44) and without HPS (n = 89) and 25 healthy controls were studied. Plasma levels of S1P, NO, and markers of systemic inflammation were studied. In a murine model of common bile duct ligation (CBDL), variations in pulmonary vasculature, arterial oxygenation, liver fibrosis, and inflammation were estimated before and after administration of S1P and fingolimod. RESULTS: Log of plasma S1P levels was significantly lower in patients with HPS than in those without HPS (3.1 ± 1.4 vs. 4.6 ± 0.2; p <0.001) and more so in severe intrapulmonary shunting than in mild and moderate intrapulmonary shunting (p <0.001). Plasma tumour necrosis factor-α (76.5 [30.3-91.6] vs. 52.9 [25.2-82.8]; p = 0.02) and NO (152.9 ± 41.2 vs. 79.2 ± 29.2; p = 0.001) levels were higher in patients with HPS than in those without HPS. An increase in Th17 (p <0.001) and T regulatory cells (p <0.001) was observed; the latter inversely correlated with plasma S1P levels. In the CBDL HPS model, fingolimod restored pulmonary vascular injury by increasing the arterial blood gas exchange and reducing systemic and pulmonary inflammation, resulting in improved survival (p = 0.02). Compared with vehicle treatment, fingolimod reduced portal pressure (p <0.05) and hepatic fibrosis and improved hepatocyte proliferation. It also induced apoptotic death in hepatic stellate cells and reduced collagen formation. CONCLUSIONS: Plasma S1P levels are low in patients with HPS and even more so in severe cases. Fingolimod, by improving pulmonary vascular tone and oxygenation, improves survival in a murine CBDL HPS model. IMPACT AND IMPLICATIONS: A low level of plasma sphingosine-1-phosphate (S1P) is associated with severe pulmonary vascular shunting, and hence, it can serve as a marker of disease severity in patients with hepatopulmonary syndrome (HPS). Fingolimod, a functional agonist of S1P, reduces hepatic inflammation, improves vascular tone, and thus retards the progression of fibrosis in a preclinical animal model of HPS. Fingolimod is being proposed as a potential novel therapy for management of patients with HPS.

Inhaled nitric oxide improves the hepatopulmonary syndrome: a physiologic analysis.

The hepatopulmonary syndrome (HPS) is defined by liver dysfunction, intrapulmonary vasodilatation and abnormal oxygenation. Hypoxaemia is progressive and liver transplant is the only effective treatment. Severe hypoxaemia is a life-threatening HPS complication, particularly after transplant. We evaluated gas-exchange and haemodynamic effects of invasive therapies in a consecutive sample of 26 pre-transplant patients. Inhaled nitric oxide significantly improved partial pressure of oxygen (12.4 mm Hg; p=0.001) without deleterious effects on cardiac output. Trendelenburg positioning resulted in a small improvement, and methylene blue did not, though individual responses were variable. Future studies should prospectively evaluate these strategies in severe post-transplant hypoxaemia.

Chronic active Epstein-Barr virus infection with intrapulmonary shunting: A case report.

Chronic active Epstein-Barr virus (EBV) infection (CAEBV) is a high-mortality form of EBV infection. However, chronic hypoxemia is rare in these patients. We herein reported a case of severe hypoxemia due to intrapulmonary shunting in CAEBV. A 17-year-old girl presented with fever, dyspnea, cyanosis, and hepatosplenomegaly. Laboratory tests showed mild liver dysfunction and high copy numbers of EBV-DNA in the peripheral blood. A left supratrochlear lymph node biopsy showed infiltration of highly proliferative T lymphocytes with positive EBV encoded small RNA by in situ hybridization. Technetium-99m-labeled macroaggregated albumin and contrast-enhanced echocardiography confirmed the existence of intrapulmonary shunting, which was probably related to hepatopulmonary syndrome. The final diagnosis was CAEBV with intrapulmonary shunting. The patient was treated with cyclosporine A, etoposide, and dexamethasone. Finally, the patient died of respiratory failure. Intrapulmonary shunting is a rare complication of CAEBV. Early recognition and exploring the cause of hypoxemia should be highlighted in patients with CAEBV.

Sorafenib in Hepatopulmonary Syndrome: A Randomized, Double-Blind, Placebo-Controlled Trial.

The tyrosine kinase inhibitor sorafenib improves hepatopulmonary syndrome (HPS) in an experimental model. However, the efficacy and adverse effect profile in patients with HPS are unknown. We aimed to determine the effect of sorafenib on the alveolar-arterial oxygen gradient (AaPO2 ) at 3 months in patients with HPS. We performed a randomized, double-blind, placebo-controlled parallel trial of sorafenib in patients with HPS at 7 centers. A total of 28 patients with HPS were randomized to sorafenib 400 mg by mouth daily or a matching placebo in a 1:1 ratio. We found no statistically significant difference in the median change in AaPO2 from baseline to 12 weeks between the patients allocated to sorafenib (4.5 mm Hg; IQR, -3.8 to 7.0 mm Hg) and those allocated to placebo (-2.4 mm Hg; IQR, -4.8 to 8.2 mm Hg; P = 0.70). There was also no difference between the groups in terms of degree of intrapulmonary shunting by contrast echocardiography. Sorafenib significantly reduced circulating levels of angiogenic markers, including vascular endothelial growth factor receptors (P < 0.01) and TIE2-expressing M2 monocytes (P = 0.03), but it reduced the mental component scores of the Short Form 36 (P = 0.04), indicating a worse quality of life. In conclusion, sorafenib did not change the AaPO2 or other disease markers at 3 months in patients with HPS. Alternative antiangiogenic therapies or treatments targeting other pathways should be investigated.

Potential Clinical Targets in Hepatopulmonary Syndrome: Lessons From Experimental Models.

Hepatopulmonary syndrome (HPS) is a relatively common and potentially severe pulmonary complication of cirrhosis with increased risk of mortality. In experimental models, a complex interaction between pulmonary endothelial cells, monocytes, and the respiratory epithelium, which produces chemokines, cytokines, and angiogenic growth factors, causes alterations in the alveolar microvasculature, resulting in impaired oxygenation. Model systems are critical for evaluating mechanisms and for preclinical testing in HPS, due to the challenges of evaluating the lung in the setting of advanced liver disease in humans. This review provides an overview of current knowledge and recent findings in the rodent common bile duct ligation model of HPS, which recapitulates many features of human disease. We focus on the concepts of endothelial derangement, monocyte infiltration, angiogenesis, and alveolar type II cell dysfunction as main contributors and potential targets for therapy.

Effects of Caffeine Treatment on Hepatopulmonary Syndrome in Biliary Cirrhotic Rats.

Hepatopulmonary syndrome (HPS) is a lethal complication of cirrhosis characterized by hypoxia and overt intrapulmonary shunting. In this study, we investigated the effect of caffeine in rats with common bile duct ligation (CBDL)-induced liver cirrhosis and HPS. CBDL rats were randomly allocated to receive caffeine or vehicle for 14 days. On the 28th day after CBDL, mortality rate, hemodynamics, liver, and renal biochemistry parameters and arterial blood gas analysis were evaluated. Lung and liver were dissected for the evaluation of inflammation, angiogenesis and protein expressions. In another series with parallel groups, the intrapulmonary shunting was determined. Caffeine significantly reduced portal pressure (caffeine vs. control: 10.0 ± 3.7 vs. 17.0 ± 8.1 mmHg, p < 0.05) in CBDL rats. The mortality rate, mean arterial pressure, biochemistry data and hypoxia were similar between caffeine-treated and control groups. Caffeine alleviated liver fibrosis and intrahepatic angiogenesis but intrapulmonary inflammation and angiogenesis were not ameliorated. The hepatic VEGF/Rho-A protein expressions were down-regulated but the pulmonary inflammation- and angiogenesis-related protein expressions were not significantly altered by caffeine. Caffeine did not reduce the intrapulmonary shunting, either. Caffeine has been shown to significantly improve liver fibrosis, intrahepatic angiogenesis and portal hypertension in cirrhotic rats, however, it does not ameliorate HPS.

AMD3100 treatment attenuates pulmonary angiogenesis by reducing the c-kit (+) cells and its pro-angiogenic activity in CBDL rat lungs.

Recent studies have shown that pulmonary angiogenesis is an important pathological process in the development of hepatopulmonary syndrome (HPS), and growing evidence has indicated that Stromal cell-derived factor 1/C-X-C chemokine receptor type 4 (SDF-1/CXCR4) axis is involved in pulmonary vascular disease by mediating the accumulation of c-kit+ cells. This study aimed to test the effect of AMD3100, an antagonist of CXCR4, in HPS pulmonary angiogenesis. Common bile duct ligation (CBDL) rats were used as experimental HPS model and were treated with AMD3100 (1.25mg/kg/day, i.p.) or 0.9% saline for 3weeks. The sham rats underwent common bile duct exposure without ligation. The c-kit+ cells accounts and its angiogenic-related functions, prosurvival signals, pulmonary angiogenesis and arterial oxygenation were analysed in these groups. Our results showed that pulmonary SDF-1/CXCR4, Akt, Erk and VEGF/VEGFR2 were significantly activated in CBDL rats, and the numbers of circulating and pulmonary c-kit+ cells were increased in CBDL rats compared with control rats. Additionally, the angiogenic-related functions of c-kit+ cells and pulmonary microvessel counts were also elevated in CBDL rats. CXCR4 inhibition reduced pulmonary c-kit+ cells and microvessel counts and improved arterial oxygenation within 3weeks in CBDL rats. The pulmonary prosurvival signals and pro-angiogenic activity of c-kit+ cells were also down-regulated in AMD3100-treated rats. In conclusion, AMD3100 treatment attenuated pulmonary angiogenesis in CBDL rats and prevented the development of HPS via reductions in pulmonary c-kit+ cells and inhibition of the prosurvival signals. Our study provides new insights in HPS treatment.

CXCR2 is involved in pulmonary intravascular macrophage accumulation and angiogenesis in a rat model of hepatopulmonary syndrome.

Hepatopulmonary syndrome (HPS) is a lung complication in various liver diseases, with high incidence, poor prognosis and no effective non-surgical treatments in patients with hepatocirrhosis. Therefore, assessing HPS pathogenesis to explore proper therapy strategies is clinically relevant. In the present study, male Sprague-Dawley rats underwent sham operation or common bile duct ligation (CBDL). Two weeks post-surgery, the following groups were set up for 2 weeks of treatment: sham + normal saline, CBDL + CXCR2 antagonist SB225002, CBDL + tumour necrosis factor α (TNF-α) antagonist PTX and CBDL + normal saline groups. Liver and lung tissues were collected after mean arterial pressure (MAP) and portal venous pressure (PVP) measurements. Haematoxylin and eosin (H&E) staining (lung) and Masson staining (liver) were performed for pathological analyses. Finally, pulmonary tissue RNA and total protein were assessed for target effectors. The mRNA and protein levels of CXCR2 were significantly increased in the pulmonary tissue of CBDL rats. What's more, CXCR2 inhibition by SB225002 reduced the expression of CD68 and von Willebrand factor (vWf) in CBDL rats. Importantly, CXCR2 inhibition suppressed the activation of Akt and extracellular signal-regulated kinase (ERK) in CBDL rats. Antagonization of TNF-α with PTX down-regulated the expression of CXCR2. During HPS pathogenesis in rats, CXCR2 might be involved in the accumulation of pulmonary intravascular macrophages and angiogenesis, possibly by activating Akt and ERK, with additional regulation by TNF-α that enhanced pulmonary angiogenesis by directly acting on the pulmonary tissue. Finally, the present study may provide novel targets for the treatment of HPS.

Rosuvastatin improves hepatopulmonary syndrome through inhibition of inflammatory angiogenesis of lung.

The hepatopulmonary syndrome (HPS) is characterized by hypoxia and increased intrapulmonary shunts in cirrhotic patients. Emerging evidence showed promising results of treating HPS by abolishment of intrapulmonary inflammation and angiogenesis. Rosuvastatin is a kind of 3-hydroxy-methyl-3-glutamyl coenzyme A reductase inhibitor. In addition to lipid-lowering effects, it has anti-inflammation and anti-angiogenesis properties. We postulated that rosuvastatin treatment can ameliorate HPS. Common bile duct ligation (CBDL) was applied in an experimental HPS animal model. CBDL rats received 2-week rosuvastatin (20 mg/kg/day) treatments from the fifteenth day after operation. The haemodynamic data, blood gas analysis, liver biochemistries, tumour necrosis factor-α (TNF-α) and vascular endothelial growth factor (VEGF) were examined after rosuvastatin treatment. The liver and lung tissues were dissected for histopathological studies and protein analyses. In the parallel groups, intrapulmonary shunts were determined. The haemodynamic and liver biochemistries were not changed after rosuvastatin treatment in CBDL rats, but the alveolar-arterial oxygen pressure gradient was significantly decreased, implying that HPS-induced hypoxia was reversed after rosuvastatin treatment. In addition, rosuvastatin treatment reduced intrapulmonary shunts and plasma levels of VEGF and TNF-α. Besides, the intrapulmonary protein expression of nuclear factor kappa B (NF-κB), VEGF receptor (VEGFR)-1,2 and Rho-associated A kinase were significantly down-regulated and the intrapulmonary angiogenesis was ameliorated. We concluded that rosuvastatin alleviates experimental HPS through blockade of pulmonary inflammatory angiogenesis via TNF-α/NF-κB and VEGF/Rho-associated A kinase pathways down-regulation.

Vildagliptin ameliorates intrapulmonary vasodilatation and angiogenesis in chronic common bile duct ligation-induced hepatopulmonary syndrome in rat.

INTRODUCTION: Experimental hepatopulmonary syndrome (HPS) is best reproduced in the rat common bile duct ligation (CBDL) model. Vildagliptin (Vild) is an anti-hyperglycemic drug that exerts beneficial anti-inflammatory, anti-oxidant and anti-fibrotic effects. Therefore, the present search aimed to explore the possible effectiveness of Vild in CBDL-induced HPS model. METHODS: Four groups of male Wistar rats which weigh 220-270 g were used, including the normal control group, the sham control group, the CBDL group and CBDL+Vild group. The first three groups received i.p. saline, while the last group was treated with i.p. Vild (10 mg/kg/day) from the 15th to 28th day of the experiment. RESULTS: CBDL decreased the survivability and body weight of rats, increased diameter of the pulmonary vessels, and altered the arterial blood gases and the liver function parameters. Additionally, it increased the pulmonary expressions of endothelin-1 (ET-1) and tumor necrosis factor-α (TNF-α) mRNA as well as endothelial nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS) and vascular endothelial growth factor-A (VEGF-A) proteins. The CBDL rats also exhibited elevation of the pulmonary interleukin-6 (IL-6), dipeptidyl peptidase-4 (DPP-4) and nitric oxide (NO) levels along with reduction of the pulmonary total anti-oxidant capacity and glucagon-like peptide-1 (GLP-1) levels. Vild mitigated these alterations and improved the histopathological abnormalities caused by CBDL. CONCLUSION: Vild effectively attenuated CBDL-induced HPS through its anti-oxidant and anti-inflammatory effects along with its modulatory effects on ET-1/NOS/NO and TNF-α/IL-6/VEGF-A signaling implicated in the regulation of intrapulmonary vasodilatation and angiogenesis, respectively.

Hepatoprotective effects of vildagliptin mitigates lung biochemical and histopathological changes in experimental hepatopulmonary syndrome model in rat.

Hepatopulmonary syndrome (HPS) is a liver disease-induced pulmonary complication manifested with arterial hypoxemia. Hepatic cholestasis, encountered in several clinical situations, leads to biliary cirrhosis and HPS, both of which are best reproduced by rat common bile duct ligation (CBDL). Experience from liver transplantation suggests hepatoprotective-based therapy would be most effective in HPS treatment Dipeptidyl peptidase-4 (DPP-4) enzyme is involved in different pathogenic mechanisms of liver diseases. Vildagliptin (Vild) is a DPP-4 inhibitor which possesses favorable anti-inflammatory, anti-oxidant and anti-fibrotic effects. The present work explored hepatoprotective mechanisms of Vild and their participation in its prophylactic effectiveness in HPS induced by CBDL in rats. Male Wistar rats weighing 220-280 g were allocated into 4 groups: normal control, sham, CBDL and CBDL + Vild groups. i.p. saline was administered to the first 3 groups and i.p. Vild (10 mg/kg/day) was given to the fourth group for 6 weeks starting 2 week before CBDL. CBDL produced liver fibrosis, arterial hypoxemia and decreased survivability of rats. It altered liver functions and induced oxidative stress, pro-inflammatory cytokines [tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6)], vasodilatory molecules [endothelin-1 (ET-1), and inducible and endothelial nitric oxide synthases] and angiogenesis-associated protein [vascular endothelial growth factor-A (VEGF-A)] in liver and lung. Vild ameliorated liver fibrosis, and improved hypoxemia and survivability of CBDL rats and reversed these biochemical alterations. Prophylactic Vild administration attenuated CBDL-induced HPS in rats via direct hepatoprotective effects in the form of anti-oxidant, anti-inflammatory, anti-angiogenic and anti-fibrotic effects beside inhibition of pathological intrahepatic vasodilatation.

Sorafenib treatment improves hepatopulmonary syndrome in rats with biliary cirrhosis.

HPS (hepatopulmonary syndrome) is characterized by oxygen desaturation in patients with chronic liver disease. The initiation of HPS comes from abnormal pulmonary vasodilatation and/or angiogenesis. In the present study, we evaluated anti-angiogenesis therapy using sorafenib in experimental HPS animals. HPS was induced by CBDL (common bile duct ligation) in rats. A 2-week 10 mg·(kg of body weight)-1·day-1 treatment regimen of sorafenib or distilled water (control) was initiated 2 weeks after the surgical procedure. Haemodynamics, liver biochemistry, plasma VEGF (vascular endothelial growth factor) measurements and blood gas analysis of the CBDL rats were performed. The livers of the CBDL rats were dissected for histopathology examination, and the lungs were examined by immunohistochemical staining, real-time PCR and Western blot analysis. In another two parallel groups, intrapulmonary shunts were determined. The AaPO2 (alveolar-arterial O2 gradient) and plasma VEGF levels were reduced after sorafenib treatment [AaPO2, 7.2±3.4 mmHg in sorafenib-treated rats compared with 15.3±4.2 mmHg in controls (P=0.004); VEGF, 45.3±2.7 pg/ml in sorafenib-treated rats compared with 54.4±7.7 pg/ml in controls (P=0.021)]. Sorafenib attenuated pulmonary VEGF mRNA and VEGF, VEGFR-2 (VEGF receptor 2), phospho-VEGFR-2 and Akt protein expression. In addition, sorafenib significantly attenuated intrapulmonary angiogenesis and decreased the degree of intrapulmonary shunting by 33.7% (11.2±5.7% in sorafenib-treated rats compared with 16.9±5.9% in controls; P=0.003). Our findings suggest that sorafenib attenuates intrapulmonary shunting and decreases the AaPO2 in CBDL rats, implicating the improvement of HPS in this experimental animal model. The beneficial effect may be attributed to the reduction in intrapulmonary angiogenesis through inhibition of the VEGF/VEGFR-2/Akt pathway.

Macitentan treatment of portopulmonary hypertension with hepatopulmonary syndrome: a case report and literature review.

Pulmonary arterial hypertension-targeted therapies in portopulmonary hypertension (PoPH) are scarce, let alone for patients with chronic liver failure (CLF) and hepatopulmonary syndrome (HPS). A 48-year male was admitted to the hospital because of cirrhosis for 18 years, systemic oedema, and chest distress after exercise for 1 week. He was diagnosed with CLF, PoPH, and HPS. After 7 weeks of macitentan treatment, the patient's activity tolerance, pulmonary artery systolic pressure, arterial partial pressure of oxygen (PaO2 ), cTNI, and NT-proBNP changes indicated gradual recovery, without hepatic safety concerns. This case indicated that administering macitentan in patients diagnosed as PoPH (with CLF and HPS) may be efficient and safe enough in a clinical setting.

TNF-α neutralization improves experimental hepatopulmonary syndrome in rats.

BACKGROUND/AIM: TNF-α is increased in hepatopulmonary syndrome (HPS). Pentoxifylline (PTX) mitigated experimental HPS through the inhibition of TNF-α. However, PTX has pleiotropic effects besides the inhibition of TNF-α. This study is to neutralize TNF-α with specific monoclonal antibody to TNF-α (TNF-α McAb) to investigate the effect of TNF-α on HPS. MATERIALS AND METHODS: Hepatopulmonary syndrome was induced by common bile duct ligation (CBDL); controls were sham operated. The endpoints were 1, 2, 3, 4 and 5 weeks after surgery. (99m) Technetium-macroaggregated albumin (Tc-MAA) was to evaluate intrapulmonary arteriovenous shunts; Portal venous pressure, cardiac output and mean blood pressure (MAP) were also measured. Serum was for Alanine transaminase (ALT), endotoxin, TNF-α and nitric oxide (NO) measurements, liver for histology, lung for histology and iNOS, PI3K/Akt expression assay. RESULTS: Portal vein pressure was significantly elevated and MAP decreased in CBDL rats. Tc-MAA was mainly located in lung and very weak in brain in sham group and mainly in brain of CBDL rats. TNF-α McAb significantly decreased the radioactivity in the brain, reduced cardiac output, increased MAP and systemic vascular resistance (SVR) in CBDL animals. Serum ALT, endotoxin, TNF-α and NO were significantly increased. TNF-α McAb significantly decreased these serum indices in CBDL rats. TNF-α McAb significantly alleviated liver damage, decreased alveolar-arterial gradient and inhibited iNOS, PI3K/Akt and p-Akt expression in lung tissue. Furthermore, TNF-α McAb significantly attenuated the inflammatory response in lung. CONCLUSION: TNF-α McAb improves HPS in cirrhotic rats; this effect is likely mediated through the inhibition of TNF-α PI3K/Akt-NO pathway.

Quercetin ameliorates acute lung injury in a rat model of hepatopulmonary syndrome.

BACKGROUND: Common bile duct ligation (BDL) is a rat experimental model to induce biliary cirrhosis. Lung fibrosis and pulmonary vascular angiogenesis and congestion are the most common complications of biliary cirrhosis that is known as hepatopulmonary syndrome. The aim of the present work is to investigate the acute lung injury in a BDL model and to investigate the possible protective effect of quercetin on this injury. METHODS: Twenty-four adult male albino rats of the Wister strain (weighing 150-250 g). Animals were divided into 3 groups, with 8 rats each: Group I: Sham-operated group (control). Group II: Bile duct ligation group (BDL) sacrificed after 28 days from the surgery. Group III: Quercetin-treated bile duct ligation group (Q-BDL) was given orally by gastric gavage in a dose of 50 mg/kg/day, starting from the 4th day of the operation until the 28th day. At the end of the experiment, at day 28, all rats were sacrificed. Lung specimens were processed to measure Endothelin B receptor gene expression by PCR, lung surfactant by ELISA, "eNO" s by immunohistochemistry. Histological assessment was done using; H&E, Masson's trichrome, PAS, toluidine blue-stained semi-thin sections, transmission electron microscope. Histomorphometric and statistical studies were done. RESULTS: BDL group showed significant increase in lung index together with mononuclear cellular infiltration denoting lung inflammatory state. Also, the significant increase in pulmonary endothelial nitric oxide synthase ("eNO" s) area percent and endothelin B receptor (ETB) gene expression indicates enhanced angiogenesis. Pulmonary surfactant concentration was significantly decreased together with thickening of interalveolar septa denoting lung injury and fibrosis. Quercetin led to significant decrease in lung index, pulmonary "eNO" s area percent, ETB gene expression and significant increase in pulmonary surfactant concentration. Quercetin treatment improved histological changes and morphometric measurements, limited mononuclear cellular infiltration and decreased perivascular and perialveolar collagen deposition. CONCLUSION: Quercetin ameliorates the hepatopulmonary syndrome-induced lung injury through its anti-inflammatory, antioxidative and antifibrotic effects.

Norfloxacin therapy for hepatopulmonary syndrome: a pilot randomized controlled trial.

BACKGROUND & AIMS: The hepatopulmonary syndrome occurs in up to one-third of patients with cirrhosis. Animal models of this disease suggest that endotoxemia might cause nitric oxide-mediated vascular dilatation that can be inhibited by the antibiotic norfloxacin. We sought to test this hypothesis in humans. METHODS: We conducted a pilot randomized, controlled crossover trial of norfloxacin 400 mg twice daily for 4 weeks with a 4-week washout period to assess the feasibility of a larger trial. The primary clinical end point was change in alveolar-arterial oxygen gradient (AaDO2). RESULTS: Recruitment was challenging, and change in AaDO2 was highly variable. We recruited 9 adults (1 woman; age, 60 ± 9 years; AaDO2, 50 ± 22 mm Hg). AaDO2 decreased by 0.8 ± 4.8 and 3.4 ± 12.4 mm Hg while on norfloxacin and placebo, respectively (P = .59). CONCLUSIONS: Recruitment difficulties and variability of the primary outcome measure suggest the need for a multicenter clinical research network for future therapeutic trials in this disease. There was no major effect of norfloxacin on gas exchange in patients with hepatopulmonary syndrome.

Pulmonary angiogenesis in a rat model of hepatopulmonary syndrome.

BACKGROUND & AIMS: Hepatopulmonary syndrome (HPS), defined as intrapulmonary vasodilation, occurs in 10%-30% of cirrhotics and increases mortality. In a rat model of HPS induced by common bile duct ligation (CBDL), but not thioacetamide (TAA)-induced nonbiliary cirrhosis, lung capillary density increases, monocytes accumulate in the microvasculature, and signaling factors in the angiogenesis pathway (Akt and endothelial nitric oxide synthase [eNOS]) are activated. Pentoxifylline (PTX) directly decreases lung endothelial Akt and eNOS activation, blocks intravascular monocyte accumulation, and improves experimental HPS; we evaluated whether pulmonary angiogenesis develops in this model. METHODS: TAA- and PTX-treated animals were evaluated following CBDL. Lung angiogenesis was assessed by quantifying factor VIII-positive microvessels and levels of von Willebrand factor (vWf), vascular endothelial cadherin (VE-cadherin), and proliferating cell nuclear antigen (PCNA). Angiogenic factors including phospho-Akt, phospho-eNOS, vascular endothelial growth factor (VEGF)-A, and phospho-VEGF receptor-2 (p-VEGFR-2) were compared and monocyte accumulation was assessed. RESULTS: Following CBDL, but not TAA exposure, rats developed HPS that was temporally correlated with increased numbers of lung microvessel; increased levels of vWf, VE-cadherin and PCNA; and activation of Akt and eNOS. Angiogenesis was accompanied by increased pulmonary VEGF-A and p-VEGFR-2 levels, with VEGF-A staining in accumulated intravascular monocytes and alveolar endothelial cells. Following CBDL, PTX-treated rats had reduced numbers of microvessels, reduced lung monocyte accumulation, downregulation of pulmonary angiogenic factors, and reduced symptoms of HPS. CONCLUSIONS: A specific increase in pulmonary angiogenesis occurs as experimental HPS develops, accompanied by activation of VEGF-A-associated angiogenic pathways. PTX decreases the angiogenesis, reduces the symptoms of HPS, and downregulates VEGF-A mediated pathways.

The role of garlic in hepatopulmonary syndrome: a randomized controlled trial.

BACKGROUND: Increased nitric oxide production in cirrhosis has been commonly implicated in the genesis of hepatopulmonary syndrome (HPS). Initial studies suggested that garlic, a constituent of the daily diet, may have a role in the treatment of HPS by altering nitric oxide production. OBJECTIVE: To evaluate the effects of oral garlic supplementation on arterial blood gas parameters, and overall morbidity and mortality in patients with HPS. METHODS: Twenty-one and 20 HPS patients were randomly assigned to receive either oral garlic supplementation or placebo, respectively, and were evaluated monthly over a period of nine to 18 months. RESULTS: After nine months, garlic supplementation was associated with a 24.66% increase in baseline arterial oxygen levels (83.05 mmHg versus 66.62 mmHg; P<0.001), compared with only a 7.37% increase (68.75 mmHg versus 64.05 mmHg; P=0.02) among subjects in the placebo group. There was also a 28.35% decrease in alveolar-arterial oxygen gradient (21.35 mmHg versus 29.77 mmHg; P<0.001) among patients with HPS who received garlic, in contrast with only a 10.73% decrease (29.11 mmHg versus 32.61 mmHg; P=0.12) among those in the placebo group. After nine months, the arterial oxygen level was significantly higher (83.05 mmHg versus 68.75 mmHg; P<0.001) and the alveolar-arterial oxygen gradient was significantly lower (21.35 mmHg versus 29.11 mmHg; P<0.001) among patients receiving garlic compared with those receiving placebo. Reversal of HPS was observed in 14 of 21 patients (66.67%) on garlic supplementation (intent-to-treat analysis) and in one of 20 patients (5%) on placebo. Two of 21 patients undergoing garlic supplementation died during follow-up in contrast to seven of 20 patients who were on placebo. CONCLUSIONS: Garlic supplementation may be beneficial in patients with HPS for the reversal of intrapulmonary shunts as well as reducing hypoxemia and mortality.

A high-dose rapamycin treatment alleviates hepatopulmonary syndrome in cirrhotic rats.

BACKGROUND: Rapamycin is a type of immunosuppressive agent that acts through inhibition of mammalian target of rapamycin (mTOR). Hepatopulmonary syndrome (HPS) is a lethal complication in cirrhotic patients. It is characterized by hypoxia and increased intrapulmonary shunts, in which pulmonary inflammation and angiogenesis play important roles. The current study aimed to evaluate the effect of rapamycin on HPS using the experimental model of common bile duct ligation (CBDL)-induced cirrhosis in rats. METHODS: The rats received low-dose (0.5 mg/kg), high-dose (2 mg/kg) rapamycin, or vehicle from the 15th to the 28th day post CBDL. Then the mortality rate, hemodynamics, biochemistry parameters, arterial blood gas and plasma levels of vascular endothelial growth factor (VEGF) and tumor necrosis factor (TNF)-α were evaluated on the 28th day post CBDL. Pulmonary histopathological stains were performed, and protein expression was examined. In parallel groups, the intrapulmonary shunts of CBDL rats were measured. RESULTS: Compared with the control, a high-dose rapamycin treatment decreased portal pressure and improved hypoxia in CBDL rats. It also reduced the plasma level of VEGF and TNF-α and decreased intrapulmonary shunts. Meanwhile, it ameliorated pulmonary inflammation and angiogenesis and downregulated the protein expression of mTOR, P70S6K, nuclear factor kappa B (NFκB), VEGF, and VEGF receptor 2. In contrast, low-dose rapamycin did not attenuate intrapulmonary shunts despite ameliorating portal hypertension. CONCLUSION: High-dose rapamycin ameliorates HPS in cirrhotic rats as evidenced by the alleviated hypoxia and decreased intrapulmonary shunts. Downregulation of the mTOR/P70S6K, NFκB, and VEGF signaling pathways might play a key role.