Progressive liver failure in a patient with adult Niemann-Pick disease associated with generalized AL amyloidosis

Case Report of Gastrointestinal Bleeding in an Adult with Chronic Visceral Acid Sphingomyelinase Deficiency

Introduction

Acid sphingomyelinase deficiency (ASMD, also known as Niemann-Pick Type A and Type B disease) is a rare, inherited metabolic disorder. Liver-related issues, including cirrhosis and variceal haemorrhage, are a leading cause of early mortality in individuals with chronic forms of ASMD. Due to the rarity of this lysosomal storage disorder, there can be a lack of awareness that adults with chronic ASMD disease are at significant risk of cirrhosis, portal hypertension, and variceal bleeding. This case highlights an unusual presentation of recurrent variceal bleeding in an adult with cirrhosis and portal hypertension due to chronic visceral ASMD.

Case Presentation

A patient with severe splenomegaly was diagnosed with ASMD at age of 25. At age 64 they had multiple hospital admissions for hematochezia (originally diagnosed as ischemic colitis) accompanied by hypotension (blood pressure 91/45 mmHg), anemia (hemoglobin 8.5g/dL, ref 12-16; INR 1.4, ref ≤1.2), and mild renal insufficiency (creatinine 1.33mg/dL, ref 0.51-0.95). Colonoscopy did not reveal a source of bleeding. Computerized tomography scanning imaging showed diffuse venous collaterals and ascites. Arteriographies during subsequent episodes of bleeding were negative for active arterial intestinal bleeding. Recurrent gastrointestinal bleeding was found to originate from a varicose vein cluster connected to the right iliac vein and the superior mesenteric vein, located in the submucosa of a small intestinal loop. Multiple varices were secondary to portal hypertension in the context of cirrhosis. The patient died from recurrent variceal bleeding that exacerbated liver failure worsened by pneumonia and hypovolemic and septic shock.

Conclusions

The variceal bleeding in this patient was atypical in that it originated from venous collaterals bleeding into the small intestine rather than the more typical gastroesophageal varices observed in ASMD. With long standing liver dysfunction and gradual development of portal hypertension, intestinal varices rather than occult intestinal bleeding due to ischemia should be considered in ASMD patients presenting with either hematochezia or hematemesis.

Cause of death in patients with chronic visceral and chronic neurovisceral acid sphingomyelinase deficiency (Niemann-Pick disease type B and B variant): Literature review and report of new cases

BACKGROUND

Acid sphingomyelinase deficiency (ASMD), [Niemann-Pick Disease Types A and B (NPD A and B)], is an inherited metabolic disorder resulting from deficiency of the lysosomal enzyme acid sphingomyelinase. Accumulation of sphingomyelin in hepatocytes, reticuloendothelial cells, and in some cases neurons, results in a progressive multisystem disease that encompasses a broad clinical spectrum of neurological and visceral involvement, including: infantile neurovisceral ASMD (NPD A) that is uniformly fatal by 3years of age; chronic neurovisceral ASMD (intermediate NPD A/B; NPD B variant) that has later symptom onset and slower neurological and visceral disease progression; and chronic visceral ASMD (NPD B) that lacks neurological symptoms but has significant disease-related morbidities in multiple organ systems. The purpose of this study was to characterize disease-related morbidities and causes of death in patients with the chronic visceral and chronic neurovisceral forms of ASMD.

METHODS

Data for 85 patients who had died or received liver transplant were collected by treating physicians (n=27), or abstracted from previously published case studies (n=58). Ages at symptom onset, diagnosis, and death; cause of death; organ involvement, and morbidity were analyzed.

RESULTS

Common disease-related morbidities included splenomegaly (96.6%), hepatomegaly (91.4%), liver dysfunction (82.6%), and pulmonary disease (75.0%). The overall leading causes of death were respiratory failure and liver failure (27.7% each) irrespective of age. For patients with chronic neurovisceral ASMD (31.8%), progression of neurodegenerative disease was a leading cause of death along with respiratory disease (both 23.1%) and liver disease (19.2%). Patients with chronic neurovisceral disease died at younger ages than those with chronic visceral disease (median age at death 8 vs. 23.5years).

CONCLUSIONS

The analysis emphasizes that treatment goals for patients with chronic visceral and chronic neurovisceral ASMD should include reducing splenomegaly and improving liver function and respiratory status, with the ultimate goal of decreasing serious morbidity and mortality.

Safety study of adeno-associated virus serotype 2-mediated human acid sphingomyelinase expression in the nonhuman primate brain

Niemann-Pick disease is a lysosomal storage disorder resulting from inherited deficiency in acid sphingomyelinase (ASM). Use of adeno-associated virus serotype 2 (AAV2) to deliver human acid sphingomyelinase (hASM) is currently being explored as a means to treat the devastating neurological features of NPD, which are refractory to traditional enzyme replacement therapy. In this study, we evaluated the long-term efficacy and safety of AAV2-hASM after direct infusion into the CNS of nonhuman primates. First, we confirmed the efficacy of AAV2-hASM in naive rats, which exhibited increased ASM expression and enzyme activity after infusion, without evidence of local or systemic toxicity. Next, the model was adapted to naive nonhuman primates (NHPs) with various doses of AAV2-hASM or saline delivered into the brainstem and both thalami. Strikingly, NHPs that received a high dose of AAV2-hASM displayed significant motor deficits that were not seen in low-dose animals in both the short-term (3-month) and long-term (9-month) treatment groups. In treated NHPs, ASM expression and activity were elevated with associated alterations in the sphingolipidomic profile in brain regions transduced with AAV2-hASM. Initial histological analysis indicated marked inflammatory reactions, and immunohistochemical analysis confirmed a robust inflammatory response. Importantly, pronounced upregulation of the chemokine CCL5, a target of ASM-mediated inflammatory signaling, was detected that correlated with the inflammatory response, providing a possible mechanism for hASM-associated toxicity. This study defines dose-dependent and dose-independent toxicities of AAV2-hASM in the naive primate brain, and reveals potential challenges in the design of a clinical trial.

TNF-{alpha} plays a role in hepatocyte apoptosis in Niemann-Pick type C liver disease

Niemann-Pick type C (NPC) is a fatal autosomal recessive lysosomal storage disease clinically characterized by neurodegeneration and liver disease. Heterogeneous mutations in the NPC1 and NPC2 genes cause impaired egress of free cholesterol from lysosomes, leading to accumulation of cholesterol and glycosphingolipids. Key features of NPC liver disease include hepatic apoptosis, inflammation, and fibrosis. It is unclear what signaling events regulate these disease processes in NPC. We hypothesize that tumor necrosis factor alpha (TNF-alpha), which is involved in both proinflammatory and apoptotic signaling cascades, is a key mediator of inflammation, apoptosis, and fibrosis in NPC liver disease. In this study, we evaluated the role of TNF-alpha signaling in NPC liver disease by utilizing NPC1-specific antisense oligonucleotides to knock down NPC1 expression in control and TNF-alpha knockout mice. In the absence of TNF-alpha, NPC1 knockdown produced liver disease with significantly less inflammation, apoptosis, and fibrosis.

In vivo antisense oligonucleotide reduction of NPC1 expression as a novel mouse model for Niemann Pick type C- associated liver disease

Niemann-Pick type C (NPC) is a fatal autosomal recessive lipidosis that is characterized by lysosomal storage of cholesterol and glycosphingolipids. Patients exhibit prolonged neonatal jaundice, hepatosplenomegaly, and progressive neurodegeneration that generally result in death by the teen years. Most clinical cases are caused by mutations in the NPC1 gene. Current mouse models of NPC are not well suited for studying the liver disease due to the rapidly progressing neurological disease. To facilitate study of NPC-associated liver dysfunction, we have developed a novel mouse model using antisense oligonucleotides to ablate NPC1 expression primarily in the liver. Here, we show that the NPC1 knockdown leads to a liver disease phenotype similar to that of patients with NPC and the NPC(nih) mouse model. Key features include hepatomegaly, lipid storage, elevated serum liver enzymes, and increased apoptosis.

CONCLUSION

This novel NPC1 antisense mouse model will allow delineation of the mechanism by which NPC1 dysfunction leads to liver cell death.

Plasma chitotriosidase and CCL18: early biochemical surrogate markers in type B Niemann-Pick disease

Type B Niemann-Pick disease (NPD) is a nonneuronopathic lysosomal storage disorder which is characterized by accumulation of sphingomyelin-laden macrophages. The availability of plasma markers for storage cells may be of great value in facilitating therapeutic decisions. Given the similarity of the storage cells in NPD and Gaucher disease, we studied Gaucher plasma markers (chitotriosidase and CCL18) in two siblings homozygous for the R228C mutation in acid sphingomyelinase (ASM) and a type B course of NPD. The older sibling, first examined at the age of 9 months, showed marked hepatosplenomegaly and pulmonary involvement. The younger sibling has mild asymptomatic hepatosplenomgaly at the age of 5 months. Analysis of plasma specimens revealed markedly increased levels of chitotriosidase and CCL18 in the older sibling. In the younger child also, plasma chitotriosidase and CCL18 were clearly elevated above normal values almost immediately after birth and rapidly increased further. Histochemistry confirmed production of CCL18 by foam cells. In conclusion, plasma chitotriosidase and CCL18 may also serve as markers for the formation of pathological lipid-laden macrophages in type B NPD, in analogy to Gaucher disease. The availability of sensitive plasma surrogate markers may be of great value for monitoring the efficacy of enzyme supplementation therapy that is currently being developed.