Niemann-Pick type C (NPC) disease develops as a result of mutations in the NPC1 gene that encodes a protein involved in the net movement of unesterified cholesterol from the late endosomal/lysosomal compartment to the metabolically active pool of sterol in the cytosol of virtually every cell in the body. Although early publications emphasized the neurodegeneration occurring in children with this mutation, more recent clinical information suggests that serious liver disease also is an important part of this syndrome. These studies, therefore, were undertaken to characterize the liver dysfunction seen in mice with this same mutation. The NPC mouse develops significant hepatomegaly that reaches 8% of body weight at 5 to 6 weeks of age. This increase in liver size is associated with a linear increase in cholesterol content and with accumulation of amorphous cellular inclusions in both hepatocytes and macrophages. During the few weeks after birth, significant elevation of the plasma alkaline phosphatase level occurs, as also is seen in the human infant with this disease. At 4 to 5 weeks of age, plasma aminotransferase levels also rise abruptly. Histologically, at this time there is apoptosis, but no excess deposition of collagen or glycogen. mRNA expression is elevated for caspase 1, caspase 6, and several enzymes associated with sterol biosynthesis and bile acid formation. In conclusion, the NPC mouse has liver disease similar to that seen in the NPC infant and represents a relevant model for exploring the molecular events occurring in this form of liver disease. (HEPATOLOGY 2005;42:886-893.)
In Niemann-Pick type C (NPC) disease, cholesterol associated with either apoE or apoB100 is taken up by cells in all tissues, including the central nervous system, through clathrin-coated pits and becomes trapped in late endosomes and lysosomes. This study defines the functional, biochemical, and molecular events that ensue as nerve cell death occurs. In mice homozygous for a mutation in NPC1, neuromuscular dysfunction begins at 5 weeks and death occurs at 13 weeks of age. Cholesterol accumulates in every tissue in the body. Purkinje cell loss in the cerebellum begins at 3 to 4 weeks of age and is nearly complete by 11 weeks. This neurodegeneration in the cerebellum is associated with increases in the levels of mRNA for caspase 1, caspase 3, NPC2, LipA, apoE, apoD, glial fibrillary acidic protein, and tumor necrosis factor-alpha, but not for most target genes of the LXR nuclear receptors. The level for apoER2 is significantly reduced. These studies show there is a compensatory increase in NPC2 and LipA in an attempt to overcome the physiological defect caused by the mutation. Nevertheless, neurodegeneration proceeds utilizing apoptosis with activation of glial cells, increased apoE and apoD synthesis, and increased cholesterol turnover across the CNS.
Background: Although IgA endomysial antibodies (EMA) and tissue transglutaminase (TG) are sensitive and specific serologic tests for the diagnosis of celiac disease, there is limited information on the association of the magnitude of antibody level with the severity of the histological abnormalities of the intestine. Purpose: To determine if EMA and TG titers correlate with the severity of histological changes in patients with celiac disease. Methods: We identified 148 children from our laboratory database that had EMA, TG and intestinal biopsies performed. IgA EMA was determined by indirect immunofluorescence with results expressed as a dilutional titer with positivity determined at 1:5. IgA TG was determined by an enzyme linked human immunosorbent ELISA assay with results expressed in standardized units. A modified Marsh histological grading system was used to describe the duodenal biopsies: Type 0 normal, I increased intraepithelial lymphocytes (IEL), II hyperplastic crypts, IIIa partial villus atrophy, IIIb subtotal villus atrophy, IIIc total villous atrophy. Results: Mean values for EMA (Table 1) and TG (Table 2) progressively increased with increasing Marsh score.
Conclusion:There was considerable variability in EMA and TG levels for each Marsh grade, so that an individual level could not be utilized to predict histological severity. The data show that as a group, increasing severity of the histological lesion in celiac disease was associated with increased levels of both IgA EMA and TG antibodies.
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