The lesions of an ovine lysosomal storage disease. Initial characterization.

An inherited disease associated with deficiencies of beta-galactosidase and alpha-neuraminidase has been identified recently in sheep. The clinical signs, the deficiency of lysosomal enzymes, and the familial nature of the disorder suggested that the condition was a lysosomal storage disease. Four affected sheep were necropsied and their tissues were examined by histopathologic and histochemical methods to determine if the lesions were consistent with a lysosomal storage disease. Central nervous system neurons were enlarged with finely to coarsely granular cytoplasmic material, or less often, neurons were distended with multiple, variably-sized vacuoles. Loss of neurons without gliosis was evident and the Nissl substance was either dispersed and fragmented or condensed around the nuclei of remaining neurons. Neurons of intestinal and other peripheral ganglia, retinal ganglion cells, and heart Purkinje fibers were enlarged similarly. White matter of the cerebrum and spinal cord had numerous spheroid to ellipsoid axonal enlargements. Periportal hepatocytes and renal epithelial cells were enlarged with marked vacuolation. The neuronal storage material stained intensely with periodic acid-Schiff/alcian blue, with Luxol fast blue, for acid phosphatase, and moderately with oil red O stains. Renal and hepatocyte storage material stained intensely with oil red O and moderately with periodic acid-Schiff/alcian blue and Sudan black B stains. The lesions in these sheep were consistent with those of a lysosomal storage disease. Both neuronal and visceral storage occurred, but the neuronal storage was more severe.     

Disease-specific pathology in neurons cultured from sheep affected with ceroid lipofuscinosis

The neuronal ceroid lipofuscinoses (NCL, Batten disease) are a group of inherited neurodegenerative storage diseases in children. Mutations in different genes underlie different forms. Subunit c of mitochondrial ATP synthase is specifically stored in autofluorescent bodies in most of them, including a form in sheep. Mature bodies are lysosomal but the initial site of storage is not known, nor is it known how this leads to the characteristic neurodegeneration. Neurons were cultured in serum-free medium from control and affected sheep fetuses at 90 days gestation. They showed positive microtubule-associated protein staining, developed neurites, and had typical neuron morphology. Time-dependent accumulation of subunit c and of fluorescent storage bodies was observed in affected cells by immunocytochemistry and confocal microscopy. A small number of autofluorescent bodies were apparent after 4 days in culture. After 10 days these bodies were more numerous, more intensely autofluorescent, and often larger in size. By 14 and 21 days many neurons were packed with autofluorescent material. These bodies were not seen in control cultures. Immunocytochemistry revealed subunit c-positive storage material only in affected neurons and not in affected glial cells. Confocal microscope analysis, using organelle-specific dyes, demonstrated colocalization of autofluorescent bodies with lysosomes, not with mitochondria. Survival rates of the affected cells were unaffected by the storage body accumulation over a 3-month period. These cultures can now be used to study the mechanism of subunit c accumulation and of neurodegeneration and to test therapeutic possibilities.     

Intracellular localization of HSP73 and HSP90 in rat kidneys with acute lysosomal thesaurismosis

We previously reported that HSP73 and HSP90, major chaperone proteins, accumulated within lysosomes of proximal tubular epithelial cells in rat kidneys with acute gentamicin nephropathy. In this study, we observed serial localization of HSP73 and HSP90 in rat kidneys with acute lysosomal thesaurismosis. Sprague-Dawley rats received poly-D-glutamic acid (PDGA) (250 mg/kg per day) for 3 days, and developed acute lysosomal thesaurismosis of proximal tubular epithelial cells. The intracellular localization of HSP73 and HSP90 was examined by electron microscopy. We also compared the results with those of a non-chaperone protein, a renal isoform of argininosuccinate synthetase, which is an abundant enzyme in proximal tubular epithelial cells. After the PDGA exposure, HSP73 and HSP90 accumulated within enlarged lysosomes of proximal tubular epithelial cells. These accumulations started to appear from day 4 after the first PDGA administration, enlarged in size until day 14, and continued until day 19. Argininosuccinate synthetase also accumulated within the lysosomes, but the magnitude of this lysosomal accumulation was less than those of HSP73 and HSP90. Our findings demonstrated that HSP73 and HSP90 chaperone proteins specifically accumulated within lysosomes of proximal tubular epithelial cells during the course of PDGA-induced acute lysosomal thesaurismosis.     

Lectin histochemistry and ultrastructure of kidneys from patients with I-cell disease

The undegraded stored material in I-cell disease (ICD) includes mucopolysaccharides, lipids, and oligosaccharides. We used ten different lectins as histochemical probes to identify specific carbohydrate residues in stored materials, and electron microscopy to examine the morphology of abnormally stored material in kidneys from two patients with ICD. In both cases, all the glomerular epithelial cells (ie, podocytes), endothelial cells, and renal tubular cells were enlarged and vacuolated. Ultrastructural studies revealed both fibrillogranular material and lamellated membrane structures in the vacuoles. The cytoplasm of affected cells stained with Concanavalia ensiformis agglutinin, wheat-germ agglutinin, and succinylated-wheat-germ agglutinin, but no corresponding control cells stained with lectins. The latter findings indicate an accumulation of N-linked oligosaccharides containing alpha-mannosyl, beta-N-acetylglucosaminyl, and sialyl residues in renal cells affected by ICD.     

An electron-dense extracellular material in the nervous system of Aplysia

An electron dense material is found in the extracellular space of the nervous system of Aplysia, a marine mollusc whose ganglia are widely studied by neurobiologists. This material appears to consist of irregular electron-dense granules, with diameters of approximately 600 Å. This material is found between the glial cells that surround the neuronal perikarya. It is not found in other regions of the nervous system. Because it is found in the ganglion cell layer of the nervous system and because the neurons contain what may be the precursor of this substance, the electron-dense material is regarded as most probably being a neuronal product. The importance of this material is that it is one of the few examples of visible structure in the extracellular space of the nervous system.     

Morphometric and cytochemical analysis of lysosomes in rat Peyer's patch follicle epithelium: their reduction in volume fraction and acid phosphatase content in M cells compared to adjacent enterocytes

M cells are specialized epithelial cells over lymphoid follicles in Peyer's patches which take up viruses, bacteria, and antigenic macromolecules from the intestinal lumen. Unlike ordinary enterocytes which sequester pinocytosed material in lysosomes, M cells transport such material across the epithelium to antigen-processing areas in lymphoid follicle domes, suggesting a difference in lysosomal activity or a different route for movement of endocytic vesicles. Ileal Peyer's patches in rats were examined by electron microscopy to identify lysosomes by acid phosphatase activity. Acid phosphatase was found in dense bodies in enterocytes but not in M cells. Stereological analysis showed the volume fraction occupied by dense bodies in M cells to be 16 times less than in enterocytes (P less than .0005), even though the volume fractions of cytoplasm occupied by mitochondria in M cells and enterocytes were not significantly different. The small volume fraction of dense bodies and the absence of acid phosphatase activity in M cells thus correlate with absence of lysosomal degradation of luminal microorganisms during transport into lymphoid follicles by M cells and may provide not only a complete array of microbial antigens for initiation of immune responses, but also a route through the mucosal barrier for microorganisms which can evade local containment mechanisms.     

Prenatal lesions in an ovine fetus with GM1 gangliosidosis

Sheep affected with ovine GM1 gangliosidosis are normal at birth and develop clinical signs, initially ataxia, commencing at approximately 5 months of age, which progresses rapidly to recumbency. Superovulation and embryo transfer techniques were applied to a flock of carrier sheep of ovine GM1 gangliosidosis to increase the numbers of carrier and affected animals. A recipient ewe with 3 at-risk fetuses died at 4 months of gestation (normal ovine gestation is 5 months), and spectrofluorimetric assay of cerebral lysosomal beta-galactosidase of the fetuses showed that 2 were carriers and one was an affected fetus. The affected fetus had marked cytoplasmic enlargement and vacuolization of central and peripheral nervous system neuronal soma and of hepatocytes and renal epithelial cells. Lectin histochemistry indicated abnormal storage of complex carbohydrates, with terminal saccharide moieties consisting of beta-galactose, N-acetylneuraminic acid, and N-acetylgalactosamine. This case underlines the need for prenatal initiation of therapy and also demonstrates that vacuolization alone is not the cause of clinical signs in this lysosomal storage disease in that clinical signs do not commence until at least 5 months after vacuolization is histologically apparent.     

GM130 gain-of-function induces cell pathology in a model of lysosomal storage disease

Cell pathology in lysosomal storage diseases is characterized by the formation of distended vacuoles with characteristics of lysosomes. Our previous studies in mucopolysaccharidosis type IIIB (MPSIIIB), a disease in which a genetic defect induces the accumulation of undigested heparan sulfate (HS) fragments, led to the hypothesis that abnormal lysosome formation was related to events occurring at the Golgi level. We reproduced the enzyme defect of MPSIIIB in HeLa cells using tetracycline-inducible expression of shRNAs directed against α-N-acetylglucosaminidase (NAGLU) and addressed this hypothesis. HeLa cells deprived of NAGLU accumulated abnormal lysosomes. The Golgi matrix protein GM130 was over-expressed. The cis- and medial-Golgi compartments were distended, elongated and formed circularized ribbons. The Golgi microtubule network was enlarged with increased amounts of AKAP450, a partner of GM130 controlling this network. GM130 down-regulation prevented pathology in HeLa cells deprived of NAGLU, whereas GM130 over-expression in control HeLa cells mimicked the pathology of deprived cells. We concluded that abnormal lysosomes forming in cells accumulating HS fragments were the consequence of GM130 gain-of-function and subsequent alterations of the Golgi ribbon architecture. These results indicate that GM130 functions are modulated by HS glycosaminoglycans and therefore possibly controlled by extracellular cues.     

Endosomal/lysosomal processing of gangliosides affects neuronal cholesterol sequestration in Niemann-Pick disease type C

Niemann-Pick disease type C (NPC) is a severe neurovisceral lysosomal storage disorder caused by defects in NPC1 or NPC2 proteins. Although numerous studies support the primacy of cholesterol storage, neurons of double-mutant mice lacking both NPC1 and an enzyme required for synthesis of all complex gangliosides (β1,4GalNAc transferase) have been reported to exhibit dramatically reduced cholesterol sequestration. Here we show that NPC2-deficient mice lacking this enzyme also exhibit reduced cholesterol, but that genetically restricting synthesis to only a-series gangliosides fully restores neuronal cholesterol storage to typical disease levels. Examining the subcellular locations of sequestered compounds in neurons lacking NPC1 or NPC2 by confocal microscopy revealed that cholesterol and the two principal storage gangliosides (GM2 and GM3) were not consistently co-localized within the same intracellular vesicles. To determine whether the lack of GM2 and GM3 co-localization was due to differences in synthetic versus degradative pathway expression, we generated mice lacking both NPC1 and lysosomal β-galactosidase, and therefore unable to generate GM2 and GM3 in lysosomes. Double mutants lacked both gangliosides, indicating that each is the product of endosomal/lysosomal processing. Unexpectedly, GM1 accumulation in double mutants increased compared to single mutants consistent with a direct role for NPC1 in ganglioside salvage. These studies provide further evidence that NPC1 and NPC2 proteins participate in endosomal/lysosomal processing of both sphingolipids and cholesterol.     

Ultrastructure of the degradation of erythrocytes by thyroid epithelial cells in vivo.

The ultrastructure of the degradation of red blood cells (RBCs) in vivo by rat thyroid epithelial cells was studied. Two morphologically distinct degradative pathways appeared evident. The granular pathway was characterized by a finely mottled appearance of RBC phagosomes, first observed about the RBC periphery and later extending to the entire RBC matrix. Such phagosomes became gradually smaller, less electron dense, and indistinguishable from cellular lysosomes. The hemolytic degrative pathway was characterized by a progessive, usually homogenous decrease in the density of the RBC matrix except at the periphery of the RBC, where a thin, dense layer persisted for some time. Such phagosomes often appeared swollen relative to freshly ingested RBCs and resembled RBC ghosts. In later stages, they became irregular, smaller, and gradually indistinguishable from cellular lysosomes. Both degradative pathways were associated with ferritin-like particles. The earliest visualization of ferritin was in the cytoplasm, but in later stages it was also found to be concentrated within lysosomes and phagolysosomes.     

Routes of excretion of neuronal lysosomal dense bodies after ventricular infusion of leupeptin in the rat: a study using ubiquitin and PGP 9.5 immunocytochemistry

Summary To determine the rate and routes of removal of lysosomal, lipofuscin-like dense bodies from neurons, the protease inhibitor, leupeptin, was infused into the lateral ventricle of rats for up to nine days. After seven days a number of animals were then allowed to recover. The formation and later disappearance of dense bodies was followed by morphology and immunocytochemistry. After 48 h of infusion lysosomal dense bodies in large numbers appeared in cortical, hippocampal and cerebellar neurons, which also showed increased ubiquitin immunoreactivity, as well as in other cell types. By 3–4 days ubiquitin-immunoreactive dense bodies were equally distributed between neurons and astroglia. After seven to nine days of infusion ubiquitin immunoreactive dense bodies filled neuronal perikarya, dendrites and expanded initial segments of many axons and were abundant in glial processes. All dense bodies studied by electron microscopy were ubiquitin immunoreactive. After four days of recovery dense bodies were markedly fewer in neuronal perikarya, and virtually all were now within glial processes. From 7 to 28 days of recovery, when most neurons appeared normal, lipofuscin bodies remained in axon initial segments and in reduced numbers in glial processes, particularly around blood vessels and beneath the pia of hippocampus and of cerebellar cortex. Thus, neurons probably have a steady passage of short lived proteins through the lysosomal excretory pathway. The observed temporal sequence of events on recovery suggests that secondary lysosomes probably pass rapidly from neuronal perikarya and dendrites to astrocytes and thus to the vascular bed or pia-arachnoid. The mechanism of cell-to-cell transfer is not clear from this study.     

Ubiquitin immunoreactive structures in normal human brains. Distribution and developmental aspects

Ubiquitin-immunoreactive structures in normal human brains ranging in age from 2 months to 91 years were studied with light and electron microscopy. Antibodies to ubiquitin immunostained structures in both neurons and glia. In the cerebrum, ubiquitin-immunoreactive, coarsely granular structures were most consistent with dystrophic neurites. They were most numerous in middle and upper cortical layers, especially lamina II of the entorhinal cortex and the cortical and accessory basal nuclei of the amygdala. Dystrophic neurites were first detected in brains of young adults, increased with age, and were numerous in the oldest brains. One of the normal elderly subjects had a small number of senile plaques with dystrophic neurites similar to those in the gray matter of the other brains, except for their location adjacent to amyloid deposits. With immunoelectron microscopy, dystrophic neurites were nonmyelinated neuronal processes containing dense, lamellar bodies, and finely granular material. White matter consistently had more immunoreactive structures than gray matter at all ages. The immunoreactive structures in white matter were smaller, less coarsely granular "dot-like" structures. With immunoelectron microscopy, dot-like structures were composed of dense inclusions within glial cells and focal swellings in myelin lamellae containing heterogeneous dense material. Only rarely were axons immunostained. Axonal spheroids in the basal ganglia, substantia nigra, and dorsal medulla were ubiquitin-immunoreactive. Spheroids were detected in these locations as early as the second decade, and they increased in number with age. A few dystrophic axons could be detected in spinal nerve roots of the oldest subjects. Other ubiquitin-immunoreactive structures included nuclei of small granular neurons, especially those in lamina II of the neocortex of the youngest brains; round cytoplasmic inclusions in tanycytes of all brains; and intranuclear Marinesco bodies in the substantia nigra and eosinophilic cytoplasmic inclusions in inferior olivary neurons in the oldest brains. These results demonstrate the spectrum of ubiquitinated structures in normal brains and suggest that progressive axonal dystrophy may be a more common age-related pathologic alteration of the brain than formerly recognized.     

Alleviation of neuronal ganglioside storage does not improve the clinical course of the Niemann-Pick C disease mouse

Niemann-Pick disease Type C (NP-C) is a progressive neurodegenerative disorder caused by mutations in the NPC1 gene and characterized by intracellular accumulation of cholesterol and sphingo-lipids. The major neuronal storage material in NP-C consists of gangliosides and other glycolipids, raising the possibility that the accumulation of these lipids may participate in the neurodegenerative process. To determine if ganglioside accumulation is a crucial factor in neuropathogenesis, we bred NP-C model mice with mice carrying a targeted mutation in GalNAcT, the gene encoding the beta-1-4GalNAc transferase responsible for the synthesis of GM2 and complex gangliosides. Unlike the NP-C model mice, these double mutant mice did not exhibit central nervous system (CNS) accumulation of gangliosides GM2 or of glycolipids GA1 and GA2. Histological analysis revealed that the characteristic neuronal storage pathology of NP-C disease was substantially reduced in the double mutant mice. By contrast, visceral pathology was similar in the NP-C and double mutant mice. Most notably, the clinical phenotype of the double mutant mice, in the absence of CNS ganglioside accumulation and associated neuronal pathology, did not improve. The results demonstrate that complex ganglioside storage, while responsible for much of the neuronal pathology, does not significantly influence the clinical phenotype of the NP-C model.     

Intestinal fine structure in crohn's disease

Summary Resected intestines from eight patients with Crohn's disease and three control cases were investigated by transmission electron microscopy. Characteristic changes were observed in the mucosa of all Crohn's disease specimens, most typically an infiltration of numerous macrophages into the propria. These cells displayed large lysosomes with inclusions which were mainly dense, irregularly shaped and composed of aggregated particles and bizarre-shaped, myelin-like figures. Similar inclusions were also found in the lysosomes of the surface epithelial cells and the macrophages in the submucosa. This latter layer otherwise consisted of an oedematous, collagenous connective tissue. The muscularis appeared structurally unaffected. Qualitatively, the findings were almost identical in all patients with Crohn's disease, but varied quantitatively without any clear correlation with the clinical histories. Moreover, in all cases typical alterations were found not only in the macroscopically most clearly affected parts of the intestines, but also in grossly normal regions, close to the margins of resection.The analogy of the fine structural findings with those of granulomas produced by injection of bacteria into experimental animals suggests that a microbial invasion of the intestinal wall may have initiated the disease. It therefore seems reasonable to assume that the lysosomal inclusions we observed represent partly degraded bacteria. More occasionally, virus-like particles were found within the lysosomes of the epithelial cells and the macrophages in the underlying propria. In view of the diffuse spread of the alterations it seems possible that there exists a generalized defect in the barrier function of the intestine in Crohn's disease. This could lead to passage of bacteria and/or other agents into the mucosa, followed by an influx of inflammatory cells from the blood. Storage of non-degradable microbial components in macrophages could then be responsible for the initiation and propagation of a chronic inflammatory process, similar to that of other granulomatous disorders.     

The fine structure of Brunn's nests in human bladder urothelium

The aetiology, morphology and clinical significance of Brunn's nests in human bladder urothelium are poorly understood. In the present study, 9% of a population of 100 consenting patients undergoing diagnostic or review cystoscopies were histologically found to have Brunn's nests, although their presence was not detected endoscopically. Of the nine cases, four were diagnosed with cystitis cystica, two with bladder papillomata, one with transitional cell carcinoma and cystitis cystica, and two were considered to be macroscopically normal. Mucosal biopsies were removed from areas unaffected by macroscopic abnormalities. Brunn's nests consisted of rounded collections of cells, whose nuclei contained prominent nucleoli and occasional nuclear bodies. The cytoplasm frequently contained clusters of mitochondria, together with Golgi membranes and cisternae of granular endoplasmic reticulum while small membrane bound vesicles containing electron dense material were present in some cells. Presumptive lysosomes were rarely observed. Thus Brunn's nest cells generally resembled normal urothelial cells in both their nuclear and cytoplasmic fine structure. Brunn's nests were surrounded by a basal lamina and loose connective tissue containing fenestrated capillaries.     

Further studies on ectopic dendrite growth and other geometrical distortions of neurons in feline GM1 gangliosidosis

Systematic Golgi studies have been performed on major subcortical, diencephalic, brain stem and spinal cord regions from cats with the inherited neuronal storage disease, GM1 gangliosidosis. Resulting data have been compared with other Golgi studies of neuronal storage disorders in man and animals, including an earlier, more limited examination of this same disease model. These previous studies have shown that in human and feline gangliosidoses cortical pyramidal neurons undergo remarkable changes in soma-dendritic geometry. The latter include the formation of conspicuous cellular enlargements between somata and axonal initial segments (meganeurites) and the sprouting of secondary neuritic processes from this same region of the cell. Further, ultrastructural studies have revealed normal appearing synapses on the surface of this ectopically placed dendritic-like membrane. Results of the present study indicate that the distribution of meganeurites, secondary neurites and other geometrical distortions of neurons in GM1 gangliosidosis varies with cell type and brain region. This cell type-specific response to the metabolic error and subsequent storage could be categorized in three ways. Firstly, certain types of cells (e.g. multipolar neurons of the amygdala and claustrum) exhibited changes similar to those reported for cortical pyramidal neurons. That is, cells of these regions either displayed spine or neurite-bearing meganeurites, or enlarged axon hillocks which were covered with similar processes. Other types of neurons did not demonstrate ectopic neurite growth or spine-covered meganeurites, but did display prominent aspiny meganeurites (e.g. neurons of the superior colliculus, periaqueductal gray, hypothalamus and basal forebrain nuclei). A third category of neurons did not possess meganeurites or neurite growth but instead demonstrated massive somatic expansion which exceeded that observed in meganeurite-bearing cell types (e.g. certain brain stem and spinal cord neurons). These data have been compared with the more limited Golgi studies of other types of neuronal storage disorders and the same types of neurons appeared to respond in similar fashion across this spectrum of diseases. The data presented and discussed in this paper demonstrate three significant morphological events which occur in neurons as a result of lysosomal hydrolase deficiency. These are storage, which occurs in all neurons but manifests as meganeurite formation or somatic enlargement depending on the cell type, axon hillock or meganeurite-associated spine and neurite growth, and new synapse formation on spine-covered meganeurites and on neurites.(ABSTRACT TRUNCATED AT 250 WORDS)     

The fine structure of dense lysosomes isolated from rat spleen.

A dense fraction from rat spleen was shown to consist of membrane bound organelles of varying shape and size which were packed with electron dense particles with the appearance of ferritin. Electron microscope microanalysis confirmed that iron was present in the organelles and the amount correlated with the density as noted in transmission electron microscopy. The organelles also stained, positively for acid phosphatase and, therefore, confirmed the biochemical findings that dense lysosomes (L30) had been isolated. The role lysosomes play in the degradation of red blood cells, and as possible sites of iron storage, are briefly discussed.     

Tissue and cellular distribution of subunit c of ATP synthase in Batten disease (neuronal ceroid-lipofuscinosis)

The major protein component of the storage bodies in the late infantile (LIB) and juvenile (JB) forms of Batten disease is subunit c of ATP synthase (subunit c). Ultrastructurally the stored material may appear as curvilinear bodies, fingerprint profiles, or a mixture of both, dependent upon the form of Batten disease and the cell type. The mnd/mnd mouse, an animal model for Batten disease, also stores subunit c and has loosely stacked lamellae within the neurons of the brain and in other cells and tissues. Using a range of tissue samples, immunolocalization, using avidin-biotin techniques at the LM level and postembedding immunogold-labelling (5 nm) with silver enhancement at the EM level, were used to investigate specific subunit c immunoreactivity. Subunit c storage was displayed in a number of cells, including neurons, muscle cells, adipocytes, macrophages, endothelial and some epithelial cells, and exocrine and endocrine cells. By EM, subunit c was localized to all curvilinear-type storage bodies, but to nowhere else within the cell. It was not present over fingerprint profiles, the characteristic storage pattern of neurons within the JB gut, possibly due to steric factors. Preliminary studies in the mnd mouse showed subunit c immunoreactivity localized to storage profiles seen ultrastructurally in neurons of the brain, and liver and heart cells. We suggest that accumulation and distribution of subunit c within a variety of cell types, and its consistent absence in others, may be related to the particular cell type's longevity and its metabolic demand. © 1995 Wiley-Liss, Inc.     

Neuronal and epithelial cell rescue resolves chronic systemic inflammation in the lipid storage disorder Niemann-Pick C

Chronic systemic inflammation is thought to be a major contributor to metabolic and neurodegenerative diseases. Since inflammatory components are shared among different disorders, targeting inflammation is an attractive option for mitigating disease. To test the significance of inflammation in the lipid storage disorder (LSD) Niemann-Pick C (NPC), we deleted the macrophage inflammatory gene Mip1a/Ccl3 from NPC diseased mice. Deletion of Ccl3 had been reported to delay neuronal loss in Sandhoff LSD mice by inhibiting macrophage infiltration. For NPC mice, in contrast, deleting Ccl3 did not retard neurodegeneration and worsened the clinical outcome. Depletion of visceral tissue macrophages also did not alter central nervous system (CNS) pathology and instead increased liver injury, suggesting a limited macrophage infiltration response into the CNS and a beneficial role of macrophage activity in visceral tissue. Prevention of neuron loss or liver injury, even at late stages in the disease, was achieved through specific rescue of NPC disease in neurons or in liver epithelial cells, respectively. Local epithelial cell correction was also sufficient to reduce the macrophage-associated pathology in lung tissue. These results demonstrate that elevated inflammation and macrophage activity does not necessarily contribute to neurodegeneration and tissue injury, and LSD defects in immune cells may not preclude an appropriate inflammatory response. We conclude that inflammation remains secondary to neuronal and epithelial cell dysfunction and does not irreversibly contribute to the pathogenic cascade in NPC disease. Without further exploration of possible beneficial roles of inflammatory mediators, targeting inflammation may not be therapeutically effective at ameliorating disease severity.