Liver findings in Niemann-Pick disease type C

The Npc2Gt(LST105)BygNya mouse signifies pathological changes comparable to human Niemann-Pick type C2 disease

INTRODUCTION

Niemann-Pick type C2 disease (NP-C2) is a fatal neurovisceral disorder caused by defects in the lysosomal cholesterol transporter protein NPC2. Consequently, cholesterol and other lipids accumulate within the lysosomes, causing a heterogeneous spectrum of clinical manifestations. Murine models are essential for increasing the understanding of the complex pathology of NP-C2. This study, therefore, aims to describe the neurovisceral pathology in the NPC2-deficient mouse model to evaluate its correlation to human NP-C2.

METHODS

Npc2-/- mice holding the LST105 mutation were used in the present study (Npc2Gt(LST105)BygNya). Body and organ weight and histopathological evaluations were carried out in six and 12-week-old Npc2-/- mice, with a special emphasis on neuropathology. The Purkinje cell (PC) marker calbindin, the astrocytic marker GFAP, and the microglia marker IBA1 were included to assess PC degeneration and neuroinflammation, respectively. In addition, the pathology of the liver, lungs, and spleen was assessed using hematoxylin and eosin staining.

RESULTS

Six weeks old pre-symptomatic Npc2-/- mice showed splenomegaly and obvious neuropathological changes, especially in the cerebellum, where initial PC loss and neuroinflammation were evident. The Npc2-/- mice developed neurological symptoms at eight weeks of age, severely progressing until the end-stage of the disease at 12 weeks. At the end-stage of the disease, Npc2-/- mice were characterized by growth retardation, tremor, cerebellar ataxia, splenomegaly, foam cell accumulation in the lungs, liver, and spleen, brain atrophy, pronounced PC degeneration, and severe neuroinflammation.

CONCLUSION

The Npc2Gt(LST105)BygNya mouse model resembles the pathology seen in NP-C2 patients and denotes a valuable model for increasing the understanding of the complex disease manifestation and is relevant for testing the efficacies of new treatment strategies.

A Retrospective Multicentric Study of 34 Patients with Niemann-Pick Type C Disease and Early Liver Involvement in France

OBJECTIVE

To describe the clinical features and course of liver involvement in a cohort of patients with Niemann-Pick type C disease (NP-C), a severe lysosomal storage disorder.

STUDY DESIGN

Patients with genetically confirmed NP-C (NPC1, n = 31; NPC2, n = 3) and liver involvement before age 6 months were retrospectively included. Clinical, laboratory test, and imaging data were collected until the last follow-up or death; available liver biopsy specimens were studied using anti-CD68 immunostaining.

RESULTS

At initial evaluation (median age, 17 days of life), all patients had hepatomegaly, 33 had splenomegaly, and 30 had neonatal cholestasis. Portal hypertension and liver failure developed in 9 and 4 patients, respectively. Liver biopsy studies, performed in 16 patients, revealed significant fibrosis in all 16 and CD68⁺ storage cells in 15. Serum alpha-fetoprotein concentration measured in 21 patients was elevated in 17. Plasma oxysterol concentrations were increased in the 16 patients tested. Four patients died within 6 months of life, including 3 from liver involvement. In patients who survived beyond age 6 months (median follow-up, 6.1 years), cholestasis regressed in all, and portal hypertension regressed in all but 1; 25 patients developed neurologic involvement, which was fatal in 16 patients.

CONCLUSIONS

Liver involvement in NP-C consisted of transient neonatal cholestasis with hepatosplenomegaly, was associated with liver fibrosis, and was responsible for death in 9% of patients. The combination of liver anti-CD68 immunostaining, serum alpha-fetoprotein measurement, and studies of plasma biomarkers should facilitate early identification of NP-C.

GCase and LIMP2 Abnormalities in the Liver of Niemann Pick Type C Mice

The lysosomal storage disease Niemann-Pick type C (NPC) is caused by impaired cholesterol efflux from lysosomes, which is accompanied by secondary lysosomal accumulation of sphingomyelin and glucosylceramide (GlcCer). Similar to Gaucher disease (GD), patients deficient in glucocerebrosidase (GCase) degrading GlcCer, NPC patients show an elevated glucosylsphingosine and glucosylated cholesterol. In livers of mice lacking the lysosomal cholesterol efflux transporter NPC1, we investigated the expression of established biomarkers of lipid-laden macrophages of GD patients, their GCase status, and content on the cytosol facing glucosylceramidase GBA2 and lysosomal integral membrane protein type B (LIMP2), a transporter of newly formed GCase to lysosomes. Livers of 80-week-old Npc1-/- mice showed a partially reduced GCase protein and enzymatic activity. In contrast, GBA2 levels tended to be reciprocally increased with the GCase deficiency. In Npc1-/- liver, increased expression of lysosomal enzymes (cathepsin D, acid ceramidase) was observed as well as increased markers of lipid-stressed macrophages (GPNMB and galectin-3). Immunohistochemistry showed that the latter markers are expressed by lipid laden Kupffer cells. Earlier reported increase of LIMP2 in Npc1-/- liver was confirmed. Unexpectedly, immunohistochemistry showed that LIMP2 is particularly overexpressed in the hepatocytes of the Npc1-/- liver. LIMP2 in these hepatocytes seems not to only localize to (endo)lysosomes. The recent recognition that LIMP2 harbors a cholesterol channel prompts the speculation that LIMP2 in Npc1-/- hepatocytes might mediate export of cholesterol into the bile and thus protects the hepatocytes.

Hepatic and neuronal phenotype of NPC1-/- mice

Niemann-Pick type C disease (NPC) is a fatal autosomal recessive disorder characterized by a defect in the intracellular transport of lipoproteins leading to the accumulation of lipids in diverse tissues. A visceral and neuronal phenotype mimicking human NPC1 disease has been described in NPC1 mutant mice. These mice are by now the most widely used NPC1 rodent model to study NPC and developmental compounds against this devastating disease. Here we characterized NPC1-/- mice for their hepatic and neuronal phenotype to confirm the stability of the phenotype, provide a characterization of disease progression and pinpoint the age of robust phenotype onset. Animals of 4-10 weeks of age were analyzed for general health, motor deficits as well as hepatic and neuronal alterations with a special focus on cerebellar pathology. Our results show that NPC1-/- mice have a reduced general health at the age of 9-10 weeks. Robust motor deficits can be observed even earlier at 8 weeks of age. Hepatic changes included increased organ weight and cholesterol levels at 6 weeks of age accompanied by severely increased liver enzyme levels. Analysis of NPC1-/- brain pathology showed decreased cholesterol and increased Aβ levels in the hippocampus at the age of 6 weeks. Further analysis revealed a decrease of the cytokine IL-12p70 in the cerebellum along with a very early increase of astrocytosis. Hippocampal IL-12p70 levels were increased at the age of 6 weeks followed by increased activated microglia levels. By the age of 10 weeks, also cerebellar Aβ levels were increased along with strongly reduced Calbindin D-28k levels. Our results validate and summarize the progressive development of the hepatic and neuronal phenotype of NPC1-/- mice that starts with cerebellar astrocytosis, making this mouse model a valuable tool for the development of new compounds against NPC.

Paediatric fatty liver disease (PeFLD): All is not NAFLD - Pathophysiological insights and approach to management

The recognition of a pattern of steatotic liver injury where histology mimicked alcoholic liver disease, but alcohol consumption was denied, led to the identification of non-alcoholic fatty liver disease (NAFLD). Non-alcoholic fatty liver disease has since become the most common chronic liver disease in adults owing to the global epidemic of obesity. However, in paediatrics, the term NAFLD seems incongruous: alcohol consumption is largely not a factor and inherited metabolic disorders can mimic or co-exist with a diagnosis of NAFLD. The term paediatric fatty liver disease may be more appropriate. In this article, we summarise the known causes of steatosis in children according to their typical, clinical presentation: i) acute liver failure; ii) neonatal or infantile jaundice; iii) hepatomegaly, splenomegaly or hepatosplenomegaly; iv) developmental delay/psychomotor retardation and perhaps most commonly; v) the asymptomatic child with incidental discovery of abnormal liver enzymes. We offer this model as a means to provide pathophysiological insights and an approach to management of the ever more complex subject of fatty liver.

Observational, retrospective study of a large cohort of patients with Niemann-Pick disease type C in the Czech Republic: a surprisingly stable diagnostic rate spanning almost 40 years

Background

Niemann-Pick disease type C (NPC) is a rare, fatal neurovisceral disorder with autosomal recessive inheritance, and featuring striking clinical variability dependent on the age at onset of neurological symptoms. We report data from a large cohort of 56 Czech patients with NPC diagnosed over a period of 37 years.

Methods

An observational, retrospective analysis of historic and current clinical and laboratory information was performed among all NPC patients originating from the area of the contemporary Czech Republic and diagnosed between 1975 and 2012. All patients with ≥1 positive diagnostic test and relevant clinical information were included. Data on diagnostic methods (histopathological and/or ultrastructural; biochemical; genetic), clinical status and general information on treatment were collated. Data were examined in accordance with international guidelines for the management of NPC.

Results

Between 1975 and 1985 diagnoses were based exclusively on specific histopathological findings, often at autopsy. Bone marrow smear (BMS) analyses have proved to be a very specific indicator for NPC and have become an important part of our diagnostic algorithm. Filipin staining and cholesterol esterification assays became the definitive diagnostic tests after 1985 and were applied in 24 of our patients. Since 2005, more and more patients have been assessed using NPC1/NPC2 gene sequencing. Twelve patients were diagnosed with neonatal/early-infantile onset NPC, 13 with the late-infantile onset form, 20 with the juvenile onset form, and nine with the adolescent/adult onset form. Two diagnosed patients remained neurologically asymptomatic at study completion. Nineteen patients were siblings. Causal NPC1 mutations were determined in 38 patients; two identical NPC2 mutations were identified in one patient. In total, 30 different mutations were identified, 14 of which have been confirmed as novel. The frequency of individual mutated NPC1 alleles in our cohort differs compared with previous published data: the most frequent mutant NPC1 allele was p.R1186H (n = 13), followed by p.P1007A (n = 8), p.S954L (n = 8) and p.I1061T (n = 4).

Conclusions

These data demonstrate the evolution of the diagnostic process in NPC over the last four decades. We estimate the contemporary birth prevalence of NPC in the Czech Republic at 0.93 per 100,000.

Recommendations for the diagnosis and management of Niemann-Pick disease type C: an update

Niemann-Pick disease type C (NP-C) is a rare inherited neurovisceral disease caused by mutations in either the NPC1 (in 95% of cases) or the NPC2 gene (in around 5% of cases), which lead to impaired intracellular lipid trafficking and accumulation of cholesterol and glycosphingolipids in the brain and other tissues. Characteristic neurological manifestations of NP-C include saccadic eye movement (SEM) abnormalities or vertical supranuclear gaze palsy (VSGP), cerebellar signs (ataxia, dystonia/dysmetria, dysarthria and dysphagia) and gelastic cataplexy. Epileptic seizures are also common in affected patients. Typically, neurological disease onset occurs during childhood, although an increasing number of cases are being detected and diagnosed during adulthood based on late-onset neurological signs and psychiatric manifestations. Categorization of patients according to age at onset of neurological manifestations (i.e. early-infantile, late-infantile, juvenile and adolescent/adult-onset) can be useful for the evaluation of disease course and treatment responses. The first international guidelines for the clinical management of NP-C in children and adults were published in 2009. Since that time a significant amount of data regarding the epidemiology, detection/diagnosis, and treatment of NP-C has been published. Here, we report points of consensus among experts in the diagnosis and treatment of NP-C based on a follow-up meeting in Paris, France in September 2011. This article serves as an update to the original guidelines providing, among other things, further information on detection/diagnostic methods, potential new methods of monitoring disease progression, and therapy. Treatment goals and the application of disease-specific therapy with miglustat are also re-evaluated.

Extracerebral biopsy in lysosomal and peroxisomal disorders. Ultrastructural findings

The lysosomal and peroxisomal disorders are characterized by specific storage affecting mainly the central nervous system with involvement of the peripheral nervous system and visceral organs. Most of these disorders can now be diagnosed by using biochemical and enzymatical assays and by molecular biology techniques, without the need for a brain biopsy used previously. Extraneural tissue biopsies have also been investigated at the ultrastructural level. The study of such tissues is still necessary when the enzymatic or biochemical defect remains unknown and when DNA studies are not informative. The choice of tissue is important. Skin and conjunctival biopsies are less traumatic and are cost-effective diagnostic tools allowing the examination of a great diversity of structures. Skeletal muscle and peripheral nerves are more frequently used for patients with a late-onset or slower course of disease. Rectal biopsy is helpful when neurons require examination in lysosomal diseases, whereas liver is more usually investigated than adrenal or testis in peroxisomal diseases. Bone marrow is most useful for Gaucher's disease while lymphocytes may be examined for all lysosomal disorders as a first diagnostic approach. Chorionic villi still have a diagnostic role in combination of electron microscopy with DNA studies in early pregnancies at-risk for neuronal ceroid lipofuscinosis. Cultured fibroblasts are less informative than other biopsy samples for the morphological evaluation of lysosomal and peroxisomal disorders.

Inherited metabolic diseases of the liver

Many inherited metabolic diseases affect the liver in neonates, children, or adults. The histopathologic changes are diverse and may be acute or chronic. They can be considered primary (when the injury is from the cytopathic effect of an accumulated metabolite) or secondary (e.g., an infection caused by an immune deficiency). All forms of liver disease are described: for example, intrahepatic cholestasis, neonatal hepatitis with giant-cell transformation, paucity of bile ducts, steatosis, steatohepatitis, necroinflammatory diseases (acute or chronic), fibrosis, cirrhosis, and neoplasms (benign or malignant). Familiarity with the morphologic changes is important in clinicopathologic correlation, diagnosis, and understanding of pathogenetic mechanisms.

Ultrastructural changes in the lung in Niemann-Pick type C mouse

The biochemical and morphological aspects of BALB/c mice with many features of the Niemann-Pick disease type C in man (NP-C mouse) have been studied extensively. However, the pulmonary pathology has not been studied extensively and we describe here some unique ultrastructural features of the lung in the NP-C mouse. Ultrastructurally, macrophages in younger mice contained osmiophilic dense granules and annulolamellar structures, but larger multilamellar concentric structures increased in the macrophages of older mice. In contrast, endothelial cells and type I pneumocytes showed membrane-bound bodies with dense granules and vesicular or vesiculogranular structures as well as amorphous materials. Type II pneumocytes were unremarkable throughout. Our study suggests that endothelial cells and type I pneumocytes are the major site of metabolic derangement resulting in pronounced morphological changes with granular and round membranous structures in the lungs of NP-C mouse. Alveolar macrophages with multilamellar concentric structures may be a result of disturbed disposal of surfactant material from type II pneumocytes rather than that from storage material of type I pneumocyte.

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

We report a case in which an adult form of Niemann-Pick disease (type B of NPD) was associated with a rapidly progressive generalized AL amyloidosis of kappa type. Both diagnosis were made by biopsy, the NPD by bone marrow biopsy and fibroblast culture, the amyloidosis by liver biopsy. Malignant non-Hodgkin lymphoma was not found. The patient, a 67-year-old woman, died from hepatic coma subsequent to a progressive liver failure. We discuss possible relations between the lysosomal storage disease and the development and rapid progression of amyloidosis.

Fatal infantile hypertrophic cardiomyopathy secondary to deficiency of heart specific phosphorylase b kinase

We describe here a male infant with a rare form of glycogenosis caused by deficiency of heart specific phosphorylase b kinase. The disease phenotype was characterized by severe glycogenosis restricted to the heart muscle with secondary rapidly progressive hypertrophic cardiomyopathy causing death at the age of 47 days.

Fetal Niemann-Pick disease type C: ultrastructural and lipid findings in liver and spleen

We present the first ultrastructural study of liver and spleen from a 20-week fetus with Niemann-Pick disease type C in correlation with lipid studies of these tissues. The lipid storage pattern was characteristic of the disease and although the distribution of the lipid storage was similar to that of affected children, ultrastructural studies emphasized that many inclusions were qualitatively different. These are discussed. Concomitant with this complex lipid storage, ultrastructural evidence of cholestasis was observed and the early hyperplasia of pericanalicular microfilaments leads us to question the presence of a toxic metabolite which might induce cholestasis by acting upon microfilaments.

Primary extracellular ceroid type lipopigment. A histochemical and ultrastructural study

An extracellular ceroid-type (ECC) lipopigment which appears histologically as wavy hyaline membranes or, less frequently, as an amorphous solid or broadly reticulated mass is described. Its ultrastructure is either amorphous or membranous and consists either of simple linear membrane-like aggregates or elaborated trilaminar membranes. The histochemical profile is, as in histiocytic intracellular ceroid, dominated by autofluorescence, strong hydrophobicity, acid and extraction resistance. Staining for aromatic acid residues and periodic acid-Schiff positivity are strong but variable. Lectin receptors are either absent or sparse. The pigment is found solely within the lipid rich tissue debris, bound to processes marked by necrosis of adipose or steatosed tissues and interpreted as originating de novo extracellularly from liquid unsaturated lipids under the influence of local enzymatic and nonenzymatic lipid oxidation catalysts. A hitherto unknown form of extracellular ceroid is the so-called membranocystic lesion found in Nasu-Hakola's disease, in several other conditions and in annular ceroid in human atheromas.

An atypical ultrastructural pattern in Fabry's disease: a study on its nature and incidence in 7 cases

This is a report on a stored lipid atypical ultrastructural pattern in skin samples of Fabry's disease expressed exclusively in the endothelium. The pattern consisted of intersecting short crescentic tightly packed membranes with a periodicity identical to that in classical ultrastructural variants. At low magnification the lysosomal aggregates of the material resembled "sunbursts" or aggregates of densely packed squirming villus-like structures. According to results of ultrastructural, lipid, and lectin histochemical analyses including analysis of the patients' blood groups, it could be concluded that it is just a variant physical state of the otherwise typical Fabry lipid. Its origin could be attributed to impeded formation (or maintenance) of larger lipid lamellae. It was found in great amounts in skin capillaries in 2 cases, and rarely in 5 additional cases. Knowledge of this atypical ultrastructural pattern is of practical significance because it could, if prevalent, cause diagnostic problems.

Subclinical course of cholesterol ester storage disease (CESD) diagnosed in adulthood. Report on two cases with remarks on the nature of the liver storage process

An extremely benign variant of cholesterol ester storage disease (CESD) was diagnosed in two female patients aged 43 and 56 years. In one of them the course was entirely subclinical until a stroke at the age of 47, most probably a complication of secondary hyperlipoproteinaemia. The diagnosis was made accidentally in vivo during extensive examination for concomitant monoclonal gammapathy. The other patient (aged 56), still displays a fairly stable course with minor dyspeptic symptoms. The clinical findings in both patients were confined to moderate well tolerated hepatomegaly, hyperlipoproteinaemia of IIb type and xanthelasmata. Acid lipase activity was markedly deficient in peripheral leukocytes and cultured fibroblasts. These cases represent a rare adult variant the existence of which should be borne in mind in the differential diagnosis of chronic liver disease in advanced age and of hyperlipoproteinaemic states. The diagnostic criteria for the routine clinicopathological steps are summarized with emphasis on a special lipopigment deposition pattern, encompassing inhibition and modification of lipofuscin generation in hepatocytes and an excess of ceroid production in both portal and intralobular histiocytes. The varied ultrastructural appearance of the lysosomal limiting membrane complex is described.

Niemann-Pick disease

Results of the investigation carried out during this decade brought unambigous evidence of biochemical heterogeneity inside the complex of Niemann-Pick disease according to which two entirely different metabolic disorders can be recognized. 1. Niemann-Pick sphingomyelinosis, a clear-cut enzymopathy, the pivotal lesion of which is the deficiency of lysosomal spingomyelinase leading to widespread lysosomal deposition of sphingomyelin liquid crystals. Two main allelic variants are known. The first one, neuronopathic (former type A) known as infantile with rapid course, may also manifest considerably prolonged course or an atypical course with predominantly visceral symptomatology. Patients with the second, visceral, variant (former type B), display mainly slow clinical course and often reach adulthood. With rare exceptions the neuronopathic variant can be biochemically recognized from the visceral one by much lower values of the in vivo sphingomyelin degradation test in the former. 2. The rest of the complex comprising types C-D differs substantially from the sphingomyelinase deficiency group by the remarkable heterogeneity in the lysosomal stored lipid pattern given by differences among the affected cell populations. Sphingomyelin storage could be proved histochemically solely in the histiocytic population together with cholesterol, neutral glycosphingolipids and lysobisphosphatidic acid, whereas the brain neurons displayed only neutral glycosphingolipid storage. There is an increasing evidence of the crucial biochemical lesion in this group being an altered intracellular traffic of exogenously derived cholesterol caused probably by its deficient translocation from lysosomes to other intracellular membrane sites. This leads to decreased cholesterol esterification rate which is the basis of the newly developed diagnostic test. Inconstant depression of sphingomyelinase activity is considered to be a secondary phenomenon. The so-called lactosylceramidosis is a rare variant pertinent to this group. The biochemical nature of type E still awaits clarification. Both groups of Niemann-Pick disease display clinical and especially histochemical features which allows to establish diagnosis in a highly efficient way already at the clinicopathological level.

The contribution of pathology to the study of storage disorders

Our purpose is to illustrate some contributions of pathology to a better knowledge of metabolic disorders affecting the brain and visceral organs. Four groups of diseases are used to that effect. A comparative study of pre- and postnatal examples of mucopolysaccharidoses I, II and III reveals for example that severe neuronal lesions are already found in fetuses and that a rough parallelism exists between the maturation of neurons and the progressive intralysosomal accumulation of undigested metabolites. The study of four patients with I-cell disease shows that the intralysosomal storage occurs nearly exclusively in fibroblasts. Since the enzyme defect has also been found in non-mesenchymal cells, other mechanisms for a proper processing of lysosomal enzymes must be available in the intact cells. Adrenoleukomyeloneuropathy is used to demonstrate that the morphological features witnessing the accumulation of the very long chain fatty acids can be different in the central and in the peripheral nervous system. Finally, juvenile dystonic lipidosis illustrate the heterogeneity of the conditions grouped under the denomination of sphingomyelinoses. These few examples confirm the role of pathology in the diagnosis of metabolic disorders and in the study of their physiopathogenesis.

Enzyme activities and phospholipid storage patterns in brain and spleen samples from Niemann-Pick disease variants: a comparison of neuropathic and non-neuropathic forms

Phospholipid levels and enzyme activities were measured in brain and spleen samples from patients with the three major variants of Niemann-Pick disease. Accumulations of sphingomyelin and bis(monoacylglycero)phosphate were demonstrated in spleen from types A and B and group C Niemann-Pick disease, whereas only in type A Niemann-Pick brain was the sphingomyelin concentration increased. Sphingomyelinase activity was markedly deficient in type A Niemann-Pick brain and spleen but residual activity of approximately 12% of control was measured in type B Niemann-Pick brain. Normal or raised sphingomyelinase and beta-glucosidase activities were measured in group C Niemann-Pick brain and spleen. Significant (17% of control) residual beta-glucosidase activity was also measured in non-neuropathic Gaucher brain. Normal levels of neutral sphingomyelinase activity were measured in brain samples from the three variants of Niemann-Pick disease. Acid sphingomyelinase activity in group C Niemann-Pick brain appeared normal with respect to enzyme extraction, pH optimum (pH 5.0) and apparent Km (approximately 0.4 mmol/L). Isoelectric focusing of brain sphingomyelinase revealed a degree of heterogeneity with activity peaks between pI 4.5 and 6.5. No defect was observed in group C Niemann-Pick brain and, although attenuated, all peaks were present in type B Niemann-Pick brain.

Niemann-Pick disease type C. Study on the nature of the cerebral storage process

A complex neuropathological study of two cases of Niemann-Pick disease (NPD) type C (NPDC) revealed some novel features in the chemical pathology of the neuronal storage. Lipid histochemistry showed the presence of a lipid which met the criteria of a neuronal glycosphingolipid. Sphingomyelin (SM) was not detected in the neurones in any of the regions examined. Lipid chemical analysis of total extracts and of partially purified lysosomal fraction of the brain cortex showed markedly increased levels of neutral ceramide hexosides especially of glucosylceramide and ceramide dihexoside (mostly of its slower band). Phospholipids were not significantly increased. Monosialogangliosides GM2 and GM3 were increased only slightly. The storage process displayed the well known fine structure and was accompanied by a marked secondary increase in some lysosomal enzyme activities. There was neuroaxonal dystrophy (NAD) of considerable intensity and extent. Many spheroids contained masses of degenerated organelles and neurofilaments in various proportions and displayed variable activities of acid phosphatase, nonspecific esterase and dehydrogenases. There was marked brain atrophy accompanied in one case by severe demyelination. Enzyme studies revealed partial decrease of sphingomyelinase (SMase) and beta-glucosidase activities in cultured fibroblasts, as well as lack of cathodic SMase activity on isoelectric focusing. No defects of these enzymes were found in the brain samples. The findings are regarded as significant since they indicate a biochemical defect in which SM is not primarily involved and which may thus be fundamentally different from that in type A of NPD.

Adrenal changes in Niemann-Pick disease: differences between sphingomyelinase deficiency and type C

Structural, chemical, and histochemical analyses of adrenal tissue performed in 8 cases of Niemann-Pick disease (NPD) revealed stark differences of storage between spingomyelinase (SMase) deficiency (6 cases) and type C (2 cases). In all the full-blown cases of the SMase deficiency group, pronounced sphingomyelin (SM) storage was found in all the zones of the cortical epithelium with slightly increasing centripetal gradient. The storage resulted in the reduction or even disappearance of lipofuscinogenesis in the reticular zone, in the reduction of the physiological fat content, in the generalized foamy transformation of the epithelium, and in moderate organomegaly. The storage was expressed in both A and B types and was roughly proportional to the storage in other viscera. The stromal storage was confined to the vascular endothelium, and in particular, to the macrophages. One of the cases showed the presence of typical spirolactone bodies unmodified in fine structure by the lysosomal storage. Their most conspicuous enzymatic activity was that of non-specific esterase and NADH tetrazolium reductase. The adrenals in type C were macroscopically and histologically normal except for a variable population of stromal foam cells. Chemically, there was slight increase in all phospholipids with borderline or moderate percentual increase of SM. There was also slight increase in some of the lower neutral glycosphingolipids. Electron microscopy dislosed rudimentar storage in lower cortical layer epithelium which by its fine structure and according to results of lipid histochemistry was qualitatively different from that in SMase deficiency. The stromal storage was expressed mainly in macrophages in which there was histochemically detectable amount of SM. There was no storage detectable in medullary cells in neither group of NPD complex. The results point not only to striking quantitative differences in storage intensity between the 2 basic groups of NPD showing the cortical epithelium in type C as being remarkably resistant to the metabolic disorder, but also to difference in quality of the storage very much like that found in other tissues, too.