Idiopathic noncirrhotic intrahepatic portal hypertension is associated with sustained ADAMTS13 Deficiency

Focused panel sequencing points to genetic predisposition in non-cirrhotic intrahepatic portal hypertension patients in India

OBJECTIVE

Non-cirrhotic intrahepatic portal hypertension (NCIPH), a portal microangiopathy affecting small portal vein radicles, is a disease of Indian sub-continent. NCIPH appears to be a complex disease with interactions between inherited and acquired factors, though the exact pathophysiological mechanism is unknown. We aimed at investigating the genetic variants that might contribute to susceptibility to NCIPH.

METHODS

In this case-control study, we analyzed genes associated with microangiopathy-VWF-ADAMTS13 (von Willebrand factor and its cleavase enzyme - a disintegrin and matrix metalloprotease with thrombospondin type-1 motifs member 13) and alternative complement system vitamin B12 metabolism and with familial NCIPH.

RESULT

Eighty-four Indian patients with liver biopsy-proven NCIPH (cases) and 103 healthy controls (matched for residential region of India) were included in the study. Targeted next-generation sequencing (NGS) panel, comprising 11 genes of interest, was done on 54 cases. Genotyping of selected variants was performed in 84 cases and 103 healthy controls. We identified variants in MBL2, CD46 and VWF genes either associated or predisposing to NCIPH. We also identified a single case with a novel compound heterozygous mutation in MBL2 gene, possibly contributing to development of NCIPH.

CONCLUSION

In this first of a kind comprehensive gene panel study, multiple variants of significance have been noted, especially in ADAMTS13-VWF and complement pathways in NCIPH patients in India. Functional significance of these variants needs to be further studied.

Dissociation in hepatic vein pressure gradient, liver stiffness measurement and complications in histological subtypes of porto-sinusoidal vascular disease

BACKGROUND AND AIMS

Portosinusoidal vascular disease (PSVD) is a broad term encompassing varied histological patterns with changes in portal tracts and sinusoids without cirrhosis. We aimed to assess whether there is any clinical and pathological difference among the various histological categories of PSVD.

PATIENTS AND METHODS

This study included liver biopsy cases classified as PSVD (2020-2022). Clinical and laboratory parameters were obtained from the electronic records. PSVD cases were histologically categorised as obliterative portal venopathy (OPV), OPV with fibrosis (OPV-F), incomplete septal cirrhosis (ISC), nodular regenerative hyperplasia (NRH), mega sinusoids with fibrosis (MSF) and unclassified. Follow-up complications were recorded.

RESULTS

PSVD categories were OPV (45 (26%)), OPV-F (37 (21.4%)), ISC (20 (11.6%)), NRH (19 (11%)), MSF (19 (11%)) and unclassified (33 (19%)). Elevated hepatic venous pressure gradient (HVPG) was noted in OPV-F (10 (IQR: 12-14.7)) and ISC (12 (IQR: 9-14)) mm Hg with higher fibrosis quantity in liver tissue and elevated procollagen III aminoterminal propeptide, which correlated with HVPG. On immunohistochemistry, OPV-F and ISC showed lesser expression of ADAMT13 in liver biopsies (p<0.001). On follow-up, ascites development was more in OPV-F and ISC than in other categories (p=0.001). Higher liver stiffness measurement (LSM) values were recorded in MSF and NRH, compared with other categories, but it did not correlate with fibrosis in liver biopsy.

CONCLUSIONS

OPV-F and ISC had higher HVPG, fibrosis, and more ascites development on follow-up than the other categories of PSVD, and all are not the same. In contrast, MSF and NRH have spuriously high LSM.

Association between gut-derived endotoxins and porto-sinusoidal vascular disorder with portal hypertension

BACKGROUND

Porto-sinusoidal vascular disorder (PSVD) is characterised by lesions involving portal veins and sinusoids in absence of cirrhosis with an unclear pathophysiology. However, its association with immunodeficiency, bowel disorders and abdominal bacterial infections supports the role of altered intestinal permeability and gut-derived endotoxins. The study aimed at assessing the association between serological markers of increased intestinal permeability, pro-aggregating/procoagulant state and liver injury in PSVD and portal hypertension.

METHODS

Thirty-three patients with biopsy-proven PSVD and portal hypertension and 33 healthy subjects were submitted to a venous blood sampling for the measurement of zonulin and lipopolysaccharides (LPS) as markers of intestinal permeability, of s-Glycoprotein VI, sP-selectin, ADAMTS13 and von Willebrand factor (vWF), as markers of platelet aggregation and microvascular inflammation, factor VIII and F1 + 2 as markers of hypercoagulability. In 17 PSVD patients, histomorphological and immunohistochemical study on liver biopsies was performed.

RESULTS

Compared with controls, PSVD patients had higher levels of LPS, zonulin, vWF, factor VIII and sP-selectin, F1 + 2. ADAMTS13 was reduced. Serum LPS correlated with zonulin, sP-selectin, FVIII and vWF. At histological analysis, PSVD specimens had increased LPS localisation, toll-like receptor-4(TLR4)-positive macrophages and platelet number compared with samples from healthy liver donors. TLR4+ macrophage number correlated with portal inflammation and fibrosis. Sinusoid dilation and capillarisation were observed. PSVD biopsies showed signs of biliary damage and reduced ductular reaction without alteration in Sox9+ cell population.

CONCLUSIONS

PSVD patients display an altered intestinal permeability and endotoxemia correlated to a pro-aggregating/procoagulant state; histologically, PSVD was associated with increased TLR4+ cell involvement and platelet clumps within sinusoids. Our study suggests that LPS-TLR4 pathway could contribute to the pathophysiological basis of PSVD with portal hypertension.

Von Willebrand Factor as a Biomarker for Liver Disease - An Update

The von Willebrand factor (vWF) is best known for its role in the hemostatic pathway, aiding platelet adhesion and aggregation, as well as circulating along with coagulation factor VIII, prolonging its half-life. However, vWF is more than a hemostatic protein and is a marker of endothelial dysfunction in patients with cirrhosis. The levels of vWF increase progressively as cirrhosis progresses. Despite its qualitative defects, it can support and carry out its hemostatic role and contribute to a pro-coagulant disbalance. Moreover, it has been shown to be a good noninvasive marker for predicting clinically significant portal hypertension (CSPH). The vWF has been shown to predict decompensation and mortality among cirrhosis patients independently of the stage of liver disease and severity of portal hypertension. Increased vWF levels in the setting of endothelial injury predict bacterial translocation and systemic inflammation. The vWF-to-thrombocyte ratio (VITRO) score adds to the diagnostic ability of vWF alone in detecting CSPH non-invasively. Not only have vWF levels been shown to help predict the risk of hepatocellular carcinoma (HCC) among cirrhosis patients, but they also predict the risk of complications post-resection for HCC and response to systemic therapies. vWF-induced portal microthrombi have been purported to contribute to the pathogenesis of acute liver failure progression as well as non-cirrhotic portal hypertension. The prospect of modulation of vWF levels using drugs such as non-selective beta-blockers, statins, anticoagulants, and non-absorbable antibiotics and its use as a predictive biomarker for the response to these drugs needs to be explored.

Porto-sinusoidal vascular disorder

It is well established that portal hypertension can occur in the absence of cirrhosis, as reported in patients with immune disorders, infections and thrombophilia. However, similar histological abnormalities primarily affecting the hepatic sinusoidal and (peri)portal vasculature have also been observed in patients without portal hypertension. Thus, the term porto-sinusoidal vascular disorder (PSVD) has recently been introduced to describe a group of vascular diseases of the liver featuring lesions encompassing the portal venules and sinusoids, irrespective of the presence/absence of portal hypertension. Liver biopsy is fundamental for PSVD diagnosis. Specific histology findings include nodular regenerative hyperplasia, obliterative portal venopathy/portal vein stenosis and incomplete septal fibrosis/cirrhosis. Since other conditions including alcohol-related and non-alcoholic fatty liver disease, or viral hepatitis, or the presence of portal vein thrombosis may occur in patients with PSVD, their relative contribution to liver damage should be carefully assessed. In addition to histology and clinical diagnostic criteria, imaging and non-invasive tests such as liver and spleen stiffness measurements could aid in the diagnostic workup. The introduction of PSVD as a novel clinical entity will facilitate collaborative studies and investigations into the underlying molecular pathomechanisms encompassed by this term.

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.

Targeting von Willebrand factor in liver diseases: A novel therapeutic strategy?

Acute and chronic liver disease are associated with substantial alterations in the hemostatic system. Evidence from both experimental and clinical studies suggests that anticoagulants slow the progression of liver disease. Efficacy of those anticoagulant drugs is, in part, attributed to a reduction of microthrombi formation within the liver. Although anticoagulant drugs show promising results, bleeding risk associated with these drugs is an obvious drawback, particularly in patients with a complex coagulopathy driven by decreased liver function. Identifying therapies that reduce intrahepatic thrombosis with minimal bleeding risk would significantly advance the field. Among the hemostatic alterations observed in patients are substantially increased levels of the platelet-adhesive protein von Willebrand factor (VWF). In contrast, levels of A Disintegrin and Metalloproteinase with Thrombospondin motifs, the enzyme that regulates VWF activity, are significantly reduced in patients with liver disease. Highly elevated VWF levels are proposed to accelerate intrahepatic thrombus formation and thus be a driver of disease progression. Strong clinical evidence suggesting a link between liver disease and changes in VWF is now being matched by emerging mechanistic data showing a detrimental role for VWF in the progression of liver disease. This review focuses on clinical and experimental evidence supporting a connection between VWF function and the progression of acute and chronic liver diseases. Furthermore, with the recent anticipated approval of several novel therapies targeting VWF, we discuss potential strategies and benefits of targeting VWF as an innovative therapy for patients with liver disease.

What makes non-cirrhotic portal hypertension a common disease in India? Analysis for environmental factors

In India, an unexplained enteropathy is present in a majority of non-cirrhotic intrahepatic portal hypertension (NCIPH) patients. Small intestinal bacterial contamination and tropical enteropathy could trigger inflammatory stimuli and activate the endothelium in the portal venous system. Groundwater contaminated with arsenic is an environmental factor of epidemic proportions in large areas of India which has similar consequences. Von Willebrand factor (a sticky protein) expressed by activated endothelium may promote formation of platelet microthrombi and occlusion of intrahepatic portal vein branches leading to NCIPH. Environmental factors linked to suboptimal hygiene and sanitation, which enter through the gastrointestinal (GI) tract, predispose to platelet plugging onto activated endothelium in portal microcirculation. Thus, NCIPH, an example of poverty linked thrombophilia, is a disease mainly affecting the lower socio-economic strata of Indian population. Public health measures to improve sanitation, provide clean drinking water and eliminate arsenic contamination of drinking water are urgently needed. Till such time as these environmental factors are addressed, NCIPH is likely to remain 'an Indian disease'.

Systematic review: role of elevated plasma von-Willebrand factor as predictor of mortality in patients with chronic liver disease

In this systematic review, we aimed to assess role of plasma von-Willebrand factor (vWF), an endothelial activation marker, as prognostic marker in patients with chronc liver disease [cirrhosis and acute-on-chronic liver failure (ACLF)]. We searched published databases using predefined keywords to identify all studies up to June 2018, in which plasma vWF (antigen or activity assay) was used as prognostic marker predicting mortality in patients with chronic liver disease. Relevant extracted data from selected studies were narratively summarized. The individual study's area under ROC curve for plasma vWF as a predictor of mortality was pooled and meta-analyzed. Six studies (cirrhosis: 5; ACLF: 1) with an aggregate data of 765 patients (cirrhosis: 715 patients; ACLF: 50 patients) were included. Baseline plasma vWF-antigen was an independent predictor of medium-term mortality in patients with cirrhosis (summary area under the curve: 0.74; 95% confidence interval: 0.70-0.79) with an optimal cutoff of 318% (216-390%; median, range) over a period of 25.6 months (23.6-33 months). Plasma vWF also predicted short-term (over 7 days) mortality in patients with ACLF. Plasma vWF levels correlated with Child's score, model for end-stage liver disease (MELD) score and hepatic venous pressure gradient and performed as well as MELD score in predicting mortality in patients with cirrhosis and ACLF. Baseline plasma vWF level predicts mortality over a medium term (1-3 years) in cirrhosis and over a short term (1 week) in ACLF patients. The marked elevation of baseline plasma vWF levels in ACLF patients was associated with drastic truncation of survival when compared with cirrhosis patients.

Duodenal variceal bleeding secondary to idiopathic portal hypertension treated with transjugular intra-hepatic porto-systemic shunt plus embolization: A case report

BACKGROUND

Duodenal varices are a lesser-known complication with non-cirrhotic portal hypertension. We report a circuitous route from missed diagnosis of duodenal varices to correction. An extremely rare case of duodenal variceal bleeding secondary to idiopathic portal hypertension (IPH) is expounded in this study, which was controlled by transjugular intra-hepatic porto-systemic shunt (TIPS) plus embolization.

CASE SUMMARY

A 46-year-old woman with anemia for two years was frequently admitted to the local hospital. Upon examination, anemia was attributed to gastrointestinal tract bleeding, which resulted from duodenal variceal bleeding detected by repeated esophagogastroduodenoscopy. At the end of a complete workup, IPH leading to duodenal varices was diagnosed. Portal venography revealed that the remarked duodenal varices originated from the proximal superior mesenteric vein. TIPS plus embolization with coils and Histoacryl was performed to obliterate the rupture of duodenal varices. The anemia resolved, and the duodenal varices completely vanished by 2 mo after the initial operation.

CONCLUSION

TIPS plus embolization may be more appropriate to treat the bleeding of large duodenal varices.

Idiopathic Portal Hypertension

Idiopathic portal hypertension (IPH) is a rare disorder characterized by clinical portal hypertension in the absence of a recognizable cause such as cirrhosis. Laboratory tests often reveal a preserved liver function with anemia, leukopenia, and thrombocytopenia due to splenomegaly. Imaging studies reveal signs of portal hypertension, whereas liver stiffness and portal pressure values are usually normal or slightly elevated. Liver biopsy is considered mandatory in order to rule out other causes of portal hypertension, mainly cirrhosis. Liver histology may only show subtle or mild changes, and the definite diagnosis of IPH often requires an expert pathologist and a high-quality specimen. The most frequent clinical presentation is variceal bleeding. Ascites is rarely observed initially, although it may occasionally appear during follow-up. Typical histological findings associated with IPH have been described in patients without portal hypertension, probably representing early stages of the disease. Although the pathophysiology of this entity remains largely unknown, it is frequently associated with underlying immunological disorders, bacterial infections, trace metal poisoning, medications, liver circulatory disturbances, and thrombotic events. The long-term prognosis of patients with IPH, where ascites and the underlying condition are important prognostic factors, is better than in patients with cirrhosis. Treatments that modify the natural history of the disease remain an unmet need, and management of IPH is frequently restricted to control of portal hypertension-related complications.

Noncirrhotic portal hypertension

PURPOSE OF REVIEW

Noncirrhotic portal hypertension represents a heterogeneous group of liver disorders that is characterized by portal hypertension in the absence of cirrhosis. The purpose of this review is to serve as a guide on how to approach a patient with noncirrhotic portal hypertension with a focus on recent developments.

RECENT FINDINGS

Recent studies pertaining to noncirrhotic portal hypertension have investigated aetiological causes, mechanisms of disease, noninvasive diagnostic modalities, clinical characteristics in the paediatric population and novel treatment targets.

SUMMARY

Noncirrhotic portal hypertension is an underappreciated clinical entity that can be difficult to diagnosis without a healthy suspicion. Diagnosis then relies on a comprehensive understanding of the causes and clinical manifestations of this disease, as well as a careful interpretation of the liver biopsy. Noninvasive approaches to diagnosis may play a significant role moving forward in this disease. Treatment in NCPH remains largely targeted at the individual sequalae of portal hypertension.

Idiopathic portal hypertension and extrahepatic portal venous obstruction

BACKGROUND

Idiopathic portal hypertension (IPH) and extrahepatic portal venous obstruction (EHPVO) are non-cirrhotic vascular causes of portal hypertension (PHT). Variceal bleed and splenomegaly are the commonest presentations.

AIM

The present review is intended to provide the existing literature on etiopathogenesis, clinical profile, diagnosis, natural history and management of IPH and EHPVO.

RESULTS

IPH and EHPVO are both characterized by normal hepatic venous pressure gradient, moderate to massive splenomegaly with preserved liver synthetic functions. While the level of block in IPH is presinusoidal, in EHPVO it is at prehepatic level. Infections, autoimmunity, drugs, immunodeficiency and prothrombotic states are possible etiological agents in IPH. Contrastingly in EHPVO, prothrombotic disorders and local factors around the portal vein are the incriminating factors. Diagnosis is often clinical, supported by simple radiological tools. Natural history is defined by episodes of variceal bleed and symptoms related to enlarged spleen. Growth failure, portal biliopathy and minimal hepatic encephalopathy are additional concerns in EHPVO. Long-term survival is reasonably good with endoscopic surveillance; however, parenchymal extinction leading to decompensation is seen in a minority of patients in both the disorders. Surgical shunts revert the complications secondary to PHT. Meso-Rex shunt has become the standard surgery in children with EHPVO.

CONCLUSION

This review gives a detailed summary of these two vascular conditions of liver-IPH and EHPVO. Further research is needed to understand the pathogenesis and natural history of these disorders.

ADAMTS13 missense variants associated with defective activity and secretion of ADAMTS13 in a patient with non-cirrhotic portal hypertension

BACKGROUND

Non-cirrhotic intrahepatic portal hypertension (NCIPH) is characterized by thrombotic microangiopathy of the portal venous system, low ADAMTS13 (a disintegrin-like and metalloproteinase with thrombospondin type 1 motifs-13), and high vWF (von Willebrand factor) levels. This study aimed to screen for ADAMTS13 mutations, focusing on the CUB domain, in these patients.

METHODS

Prospectively recruited NCIPH patients and healthy volunteers underwent tests for plasma vWF-ADAMTS13 balance. Sanger sequencing of the CUB domain of ADAMTS13 was done in a subset of the NCIPH patients, and the detected mutation was screened for in all the study participants. Next-generation sequencing of clinically relevant exome and liver immunostaining for ADAMTS13 was done in patients with detected ADAMTS13 mutation.

RESULTS

Plasma vWF-ADAMTS13 balance was significantly altered in 24 NCIPH patients (Child's class A:23, B:1) as compared to 22 controls. On initial sequencing of the CUB domain (17 cases and 3 controls), one NCIPH patient showed a rare missense variant (SNV) at position c.3829C >T resulting in p.R1277W (rs14045669). Subsequent RFLP analysis targeted to the R1277W variant did not detect this in any other NCIPH patient, nor in any of the 22 controls. The NCIPH patient with the R1277W variant had severe ADAMTS13 deficiency, consistently high vWF, other missense SNVs in ADAMTS13, vWF, and complement genes. Immunostaining of his liver biopsy revealed globules of ADAMTS13 within stellate cells.

CONCLUSIONS

We report missense variants in ADAMTS13, vWF, and complement genes in a patient with NCIPH who had decreased secretion and activity of ADAMTS13 protein. Further studies are needed in NCIPH patients in this regard.

Diagnosis and treatment guidelines for aberrant portal hemodynamics: The Aberrant Portal Hemodynamics Study Group supported by the Ministry of Health, Labor and Welfare of Japan

Idiopathic portal hypertension (IPH), causing aberrant portal hemodynamics, is a disease with an as yet unidentified cause and no established treatment protocol. The Japanese research group on IPH in Japan was set up in 1975 by the Ministry of Health, Labor and Welfare. Extrahepatic portal obstruction and Budd-Chiari syndrome (BCS) have since been added to the group's research subjects. The aims of the research group are to accurately evaluate the current status of the three diseases in Japan, elucidate their etiology and pathogenesis, and develop new treatments. Due to the long-term efforts of the Japanese research group, aberrant portal hemodynamics has been investigated in a variety of aspects, from epidemiological and pathological studies to molecular biology analyses. As a result, it has been shown that there are abnormal genes in the liver, specific for IPH. In addition, pathological findings of BCS were internationally compared and the difference in findings between Japan and Europe (or North America) has been clarified. Furthermore, it was found that complication rates of hepatocellular carcinoma in BCS were higher in Japan. Based on the research, "Diagnosis and treatment of aberrant portal hemodynamics (2001)", including diagnostic criteria for aberrant portal hemodynamics, was published in 2001. In 2013, it was revised to "Diagnosis and treatment guidelines for aberrant portal hemodynamics (2013)" after the incorporation of diagnosis and treatment in accordance with its current status.

Plasma von Willebrand factor levels predict in-hospital survival in patients with acute-on-chronic liver failure

BACKGROUND AND AIMS

Circulating levels of von Willebrand factor (vWF) predict mortality in patients with cirrhosis. We hypothesized that systemic inflammation in acute-on-chronic liver failure (ACLF) will stimulate endothelium, increase vWF levels, and promote platelet microthrombi causing organ failure.

METHODS

In this prospective study, we correlated plasma vWF levels with organ failure, liver disease severity, sepsis, and systemic inflammatory response syndrome (SIRS) and also analyzed if vWF levels predicted in-hospital composite poor outcome (i.e. death/discharged in terminal condition/liver transplantation) in consecutive ACLF patients.

RESULTS

Twenty-one of the 50 ACLF patients studied had composite poor outcome. ACLF patients had markedly elevated vWF antigen and activity (sevenfold and fivefold median increase, respectively) on days 1 and 3. Median ratio of vWF to a disintegrin and metalloprotease with thrombospondin type 1 motif, member 13 (ADAMTS13) activity on day 1 was significantly higher in ACLF patients (11.2) compared to 20 compensated cirrhosis patients (3.3) and healthy volunteers (0.9). On day 1, area under ROC curve (AUROC) to predict composite poor outcome of hospital stay for ACLF patients for vWF antigen, vWF activity, and model for end-stage liver disease (MELD) score were 0.63, 0.68, and 0.74, respectively. vWF activity correlated better with liver disease severity (MELD score, ACLF grade) and organ failure (Sequential Organ Failure Assessment [SOFA] score) than vWF antigen; in contrast, neither vWF antigen nor activity correlated with platelet count, sepsis, or SIRS.

CONCLUSIONS

vWF levels are markedly elevated, correlate with organ failure, and predict in-hospital survival in ACLF patients. This data provides a mechanistic basis for postulating that vWF-reducing treatments such as plasma exchange may benefit ACLF patients.

Update on ADAMTS13 and VWF in cardiovascular and hematological disorders

Endothelial cells (EC) respond to injury by releasing numerous factors, including von Willebrand factor (VWF). High circulating levels of unusually large VWF multimers (UL-VWFM) have strong procoagulant activity and facilitate platelet adhesion and aggregation by interacting with platelets after an acute event superimposed on peripheral arterial disease and coronary artery disease. ADAMTS13-a disintegrin-like metalloproteinase with thrombospondin motif type 1 member 13-regulates a key physiological process of coagulation in the circulation by cleaving VWF multimers into small, inactive fragments. Low levels of ADAMTS13 in the blood may play a role in cardiovascular and hematological disorders, and clarifying its role may help improve disease management. The genetic, pharmacological, physiological, and pathological aspects related to ADAMTS13/VWF have been extensively investigated. Here, we provide an update on recent findings of the relationship between ADAMTS13 and hematological/cardiovascular disorders, including thrombotic thrombocytopenic purpura, arterial thrombosis, thrombotic microangiopathy, myocardial infarction, ischemic stroke, heart failure, and hypertension.

Arsenicosis, possibly from contaminated groundwater, associated with noncirrhotic intrahepatic portal hypertension

BACKGROUND AND AIMS

Idiopathic noncirrhotic intrahepatic portal hypertension (NCIPH), a chronic microangiopathy of the liver caused by arsenicosis from use of contaminated groundwater, was reported from Asia. This study aimed to see, if in the twenty-first century, arsenicosis was present in NCIPH patients at our hospital and, if present, to look for groundwater contamination by arsenic in their residential locality.

METHODS

Twenty-seven liver biopsy proven NCIPH patients, 25 portal hypertensive controls with hepatitis B or C related cirrhosis and 25 healthy controls, matched for residential locality, were studied. Eighty-four percent to 96 % of study subjects belonged to middle or lower socioeconomic category. Arsenicosis was looked for by estimation of arsenic levels in finger/toe nails and by skin examination. Arsenic levels in nails and in ground water (in NCIPH patients with arsenicosis) was estimated by mass spectrometry.

RESULTS

Nail arsenic levels were raised in five (10 %) portal hypertensive study subjects [two NCIPH patients (both had skin arsenicosis) and three portal hypertensive controls]. All of these five patients were residents of West Bengal or Bangladesh. Skin arsenicosis was noted in three NCIPH patients (11 %) compared to none of disease/healthy controls. Ground water from residential locality of one NCIPH patient with arsenicosis (from Bangladesh) showed extremely high level of arsenic (79.5 μg/L).

CONCLUSIONS

Arsenicosis and microangiopathy of liver, possibly caused by environmental contamination continues in parts of Asia. Further studies are needed to understand the mechanisms of such 'poverty-linked thrombophilia'.

Investigation into celiac disease in Indian patients with portal hypertension

BACKGROUND

There is limited data on celiac disease in patients with cryptogenic cirrhosis or idiopathic noncirrhotic intrahepatic portal hypertension (NCIPH). Our objective was to evaluate for celiac disease in patients with portal hypertension in India.

METHODS

Consecutive patients with portal hypertension having cryptogenic chronic liver disease (cases) and hepatitis B- or C-related cirrhosis (controls) were prospectively enrolled. We studied tissue transglutaminase (tTG) antibody and duodenal histology in study patients.

RESULT

Sixty-one cases (including 14 NCIPH patients) and 59 controls were enrolled. Celiac disease was noted in six cases (including two NCIPH patients) as compared to none in controls. In a significant proportion of the remaining study subjects, duodenal biopsy showed villous atrophy, crypt hyperplasia, and lamina propria inflammation, not accompanied by raised intraepithelial lymphocytes (IELs); this was seen more commonly in cases as compared to controls. An unexpectedly high rate of tTG antibody positivity was seen in study subjects (66 %) of cases as compared to 29 % in controls (p-value < 0.001), which could indicate false-positive test result.

CONCLUSION

In this study, 10 % of patients with unexplained portal hypertension (cryptogenic chronic liver disease) had associated celiac disease. In addition, an unexplained enteropathy was seen in a significant proportion of study patients, more so in patients with cryptogenic chronic liver disease. This finding warrants further investigation.

Acute liver injury induced by low dose dimethylnitrosamine alters mediators of hepatic vascular flow

Alterations in liver vascular tone play an important role in chronic liver disease. The hepatic stellate cell (HSC) and mediators such as nitric oxide (NO) and hydrogen sulfide (H₂S) have been implicated in regulation of vascular tone and intra-hepatic pressure. Though these have been studied in chronic liver damage, changes in response to acute liver injury induced by hepatotoxins such as dimethyl nitrosamine are not well understood. Liver injury was induced in mice by a single intra-peritoneal injection of dimethylnitrosamine (DMN), following which animals were sacrificed at 24, 48 and 72 h. Changes in vascular mediators such as NO and H₂S as well as stellate cell activation was then examined. It was found that a single low dose of DMN in mice is sufficient to induce activation of hepatic stellate cells within 24 h, accompanied by oxidative stress, compromised metabolism of H₂S and decreased levels of the von Willebrand factor (vWF) cleaving protease; a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13), which functions in intravascular thrombosis. A suppression of hepatic NO levels is also initiated at this time point, which progresses further and is sustained up to 72 h, at which point the HSC activation is still present. Compromised levels of ADAMTS13 and H₂S metabolism however, begin to recover by 48 h and are almost similar to control by 72 h. In conclusion, these data suggest that even moderate acute insults in the liver can have far reaching consequences on a number of mediators of vascular flow in the liver.

Idiopathic Non-Cirrhotic Intrahepatic Portal Hypertension (NCIPH)-Newer Insights into Pathogenesis and Emerging Newer Treatment Options

Chronic microangiopathy of portal venules results in idiopathic non-cirrhotic intrahepatic portal hypertension (NCIPH). Recent data suggest a role for vasoactive factors of portal venous origin in the pathogenesis of this 'pure' vasculopathy of the liver. Enteropathies (often silent), are an important 'driver' of this disease. NCIPH is under-recognized and often mis-labeled as cryptogenic cirrhosis. Liver biopsy is needed to prove the diagnosis of NCIPH. In these patients, with advancing disease and increased porto-systemic shunting, the portal venous vasoactive factors bypass the liver filter and contribute to the development of pulmonary vascular endothelial disorders-porto-pulmonary hypertension and hepato-pulmonary syndrome as well as mesangiocapillary glomerulonephritis. Prognosis in NCIPH patients is determined by presence, recognition and management of associated disorders. With better understanding of the pathogenesis of NCIPH, newer treatment options are being explored. Imbalance in ADAMTS 13 (a disintegrin and metalloprotease with thrombospondin type 1 motif, member 13): vWF (von-Willebrand factor) ratio is documented in NCIPH patients and may have a pathogenic role. Therapeutic interventions to correct this imbalance may prove to be important in the management of NCIPH.

ADAMTS13 deficiency, despite well-compensated liver functions in patients with noncirrhotic portal hypertension

BACKGROUND

We have reported A disintegrin and metalloprotease with thrombospondin type 1 motif, member 13 (ADAMTS13) deficiency in noncirrhotic intrahepatic portal hypertension (NCIPH) patients of European origin with preserved liver function. We aimed to study ADAMTS13-von Willebrand factor (vWF) imbalance in Indian patients with NCIPH.

METHODS

Twenty-nine cases with NCIPH [22 males; 29 years (13-58); Child's A, 23; B, 6], 22 disease controls with cryptogenic chronic liver disease [15 males; 46 years (18-74); Child's A, 9; B, 9; C, 4] and 17 healthy controls [14 males; 32 years (27-45)] were enrolled in the study. We measured ADAMTS13 antigen and activity (by collagen binding assay (CBA) and by fluorescence resonance energy transfer [FRET] assay), and vWF antigen levels in plasma of study patients.

RESULTS

ADAMTS13 activity by CBA in NCIPH patients (32 %, 5 % to 100 %; median, range; p-value <0.001) and disease controls (36 %, 5 % to 144 %; p = 0.001) was significantly lower than in healthy controls (87 %; 60 % to 148 %). ADAMTS13 antigen and activity by FRET assay were also lower in cases and disease controls. ADAMTS13 activity (by CBA) to antigen ratio was lower in NCIPH and disease controls than in healthy controls. Of 29 NCIPH patients, 3 (all in Child's A) had severe ADAMTS13 deficiency (<10 % ADAMTS13 activity), and 8 (Child's A, 7; B, 1) had moderate ADAMTS13 deficiency (10 % to 25 % activity). Conversely, vWF antigen and vWF:ADAMTS13 ratio were higher in patients with NCIPH and in disease controls than in healthy controls.

CONCLUSIONS

This study validates the finding of ADAMTS13 deficiency in NCIPH despite preserved liver functions in an Indian population suggesting its involvement in pathogenesis of NCIPH.

Non-cirrhotic portal hypertension - diagnosis and management

NCPH is a heterogeneous group of liver disorders of vascular origin, leading to PHT with near normal HVPG. NCPF/IPH is a disorder of young adults or middle aged women, whereas EHPVO is a disorder of childhood. Early age acute or recurrent infections in an individual with thrombotic predisposition constitute the likely pathogenesis. Both disorders present with clinically significant PHT with preserved liver functions. Diagnosis is easy and can often be made clinically with support from imaging modalities. Management centers on control and prophylaxis of variceal bleeding. In EHPVO, there are additional concerns of growth faltering, portal biliopathy, MHE and parenchymal dysfunction. Surgical shunts are indicated in patients with failure of endotherapy, bleeding from sites not amenable to endotherapy, symptomatic hypersplenism or symptomatic biliopathy. Persistent growth failure, symptomatic and recurrent hepatic encephalopathy, impaired quality of life or massive splenomegaly that interferes with daily activities are other surgical indications. Rex-shunt or MLPVB is the recommended shunt for EHPVO, but needs proper pre-operative radiological assessment and surgical expertise. Both disorders have otherwise a fairly good prognosis, but need regular and careful surveillance. Hepatic schistosomiasis, CHF and NRH have similar presentation and comparable prognosis.

Porto-pulmonary hypertension exacerbated by platelet transfusion in a patient with ADAMTS13 deficiency

We propose that porto-pulmonary hypertension (PPH) may arise as a consequence of deficiency of ADAMTS13 (a plasma metalloprotease that regulates von Willebrand factor size and reduces its platelet adhesive activity) and provide a clinical case history to support our hypothesis. A patient with non-cirrhotic intrahepatic portal hypertension (NCIPH), ulcerative colitis and celiac disease developed symptoms of PPH, which had advanced beyond levels which would have made her an eligible candidate for liver transplantation (mean pulmonary artery pressure (PAP) 49 mm Hg). She was known to have severe ADAMTS13 deficiency, which we considered to be causative of, or contributory to her NCIPH. We postulated that increasing porto-systemic shunting associated with advancing portal hypertension would make the next encountered vascular bed, the lung, susceptible to the pathogenic process that was previously confined to the portal system, with pulmonary hypertension as its consequence. Her pulmonary artery pressures fell significantly during the next year on weekly replacement of plasma ADAMTS13 by infusions of fresh frozen plasma and conventional drug treatment of her pulmonary hypertension. Her pulmonary artery pressures had fallen to acceptable levels when, in response to platelet infusion, it rose precipitously and dangerously. The sequence strongly supports our hypothesis that PPH is a consequence of ADAMTS13 deficiency and is caused by platelet deposition in afferent pulmonary vessels.

Use of serum vitamin B12 level as a marker to differentiate idiopathic noncirrhotic intrahepatic portal hypertension from cryptogenic cirrhosis

BACKGROUND AND AIMS

Idiopathic non-cirrhotic intrahepatic portal hypertension (NCIPH) is often mis-diagnosed as cryptogenic cirrhosis. Serum vitamin B12 levels can be raised in cirrhosis, probably because of excess release or reduced clearance. Because NCIPH is characterised by long periods of preserved liver function, we examined whether serum B12 level could be used as a marker to differentiate NCIPH from cryptogenic cirrhosis.

METHODS

We analysed serum B12 levels in 45 NCIPH and 43 cryptogenic cirrhosis patients from January 2009 to September 2011.

RESULTS

Serum B12 levels were significantly lower in NCIPH patients than in cryptogenic cirrhosis patients (p < 0.001) and were useful in differentiating the two disorders (area under ROC: 0.84; 95% C.I: 0.76-0.93). Low serum B12 level (≤250 pg/ml) was noted in 25/72 (35%) healthy controls, 14/42 (33%) NCIPH patients, and 1/38 (3 %) cryptogenic cirrhosis patients. In patients with intrahepatic portal hypertension of unknown cause, serum B12 level ≤ 250 pg/ml was useful for diagnosing NCIPH (positive predictive value: 93 %, positive likelihood ratio 12.7), and serum B12 level >1,000 pg/ml was useful in ruling out NCIPH (negative predictive value: 86 %, negative likelihood ratio: 6.67). Low serum B12 levels (≤250 pg/ml) correlated with diagnosis of NCIPH after adjusting for possible confounders (O.R: 13.6; 95% C.I:1.5-126.2). Among patients in Child's class A, serum B12 level was ≤250 pg/ml in 14/35 NCIPH patients compared with 1/21 cryptogenic cirrhosis patients (O.R: 13.3; 95% C.I: 1.6-111).

CONCLUSION

Serum vitamin B12 level seems to be a useful non-invasive marker for differentiation of NCIPH from cryptogenic cirrhosis.