Therapeutic delivery of proteins to macrophages: implications for treatment of Gaucher's disease

BACKGROUND: The primary defect in Gaucher's disease, a lysosomal disorder affecting macrophages, is in the activity of glucocerebrosidase. Treatment with exogenous enzyme (modified to increase its affinity for macrophage glycoprotein receptors) aims to restore this activity. However, the fate of the exogenous enzyme in vivo is unknown. We used radiolabelled enzyme to assess macrophage receptor activity for mannosylated ligands in vivo. METHODS: We examined the uptake and tissue distribution of radiolabelled enzyme molecules by gamma scintigraphy after bolus injection of iodine-123-labelled recombinant or placental enzyme (imiglucerase and alglucerase, respectively) in eight patients with type 1 Gaucher's disease, and in one healthy individual. The metabolism of the tracer enzyme was followed by scintigraphy and by analysis of blood, urine, and faeces. RESULTS: The tracer enzyme was rapidly cleared from blood (half-life 4.7 min [SD 1.0]). Concomitantly, there was avid uptake by the liver (about 30% of the injected dose), the spleen (about 15%), and the bone marrow. 40-55% of the tracer was cleared rapidly from the viscera (half-life 1-2 h) and 45-60% was cleared slowly (half-life 34-42 h). The half-life in the bone marrow was 14.1 h. Infusion of alglucerase at dose of 5 U/kg bodyweight normalised acid beta-glucosidase activity of splenic Gaucher's cells in vivo. When the enzyme was administered at a seven-fold higher dose (35 U/kg over 1 h), the receptor-mediated uptake in vivo was saturated, as shown by the increase in blood-clearance half-life of tracer enzyme from 4.5 min to 12 min. INTERPRETATION: Avid and saturable uptake of modified glucocerebrosidase was found, which indicates high-affinity targeting to the macrophage system in vivo. The rate of enzyme turnover suggests a rational basis for use of this therapy in treatment of Gaucher's disease.     

Radiopharmacology of inhaled 133Xe in skeletal sites containing deposits of Gaucher cells

Gaucher's disease is a lysosomal storage disease in which cells of the reticuloendothelial system accumulate the lipid glucocerebroside. It is characterized by slowly progressive visceral and osseous involvement. One of the latter manifestations includes lipid infiltration of bone marrow. We monitored the rate of inhaled 133Xe uptake and wash-out over diseased and normal metaphyseal and epiphyseal areas of the knee. Twenty-two patients (15 adults, 7 children) with various degrees of previously diagnosed Gaucher's disease were positioned supine under a gamma-camera interfaced to a computer system. All patients rebreathed 133Xe gas from a closed system for 10 min followed by 14 min of wash-out. Digitized images of the lung, liver, spleen, bony sites and soft tissue were obtained at 1 min intervals during the wash-in and wash-out phases. Counts for each ROI were normalized per 100 pixels and plotted as a function (time). Maximum uptake was also calculated by relating the counts/ROI/100 pixels to the 10 min integrated lung count during equilibrium (the administered "dose"). There was essentially no 133Xe uptake in liver and spleen involved with Gaucher's disease. Monophasic uptake and biphasic wash-out curves were observed in the limited investigative population. Skeletal Gaucher deposits released the 133Xe at a greater rate relative to soft tissue.     

Immunohistochemical demonstration of acid phosphatase isoenzyme 5 (tartrate-resistant) in paraffin sections of hairy cell leukemia and other hematologic disorders

The demonstration of tartrate-resistant acid phosphatase (TRAP) activity has long been a cornerstone in the diagnosis of hairy cell leukemia (HCL). Recently a monoclonal antibody to this enzyme has been developed that can be used in an immunoperoxidase method on paraffin-embedded tissues. By using a peroxidase-labeled streptavidin biotin method, paraffin sections of B5 and formalin-fixed tissue from 86 cases of HCL (41 bone marrow, 36 spleen, 9 liver) were stained with the antibody to TRAP and compared against staining for CD20 (L26) and DBA.44 (DAKO, Carpinteria, Calif). In addition, 193 specimens (127 bone marrow, 42 lymph node, 19 spleen, 5 other) from a variety of neoplastic and nonneoplastic hematologic conditions were stained using the monoclonal antibody to TRAP. For comparison, these cases were also stained with DBA.44. In the cases of HCL, 80 of 86 specimens were immunoreactive for TRAP. While the antibody to TRAP generally stained less than 50% of the hairy cells, CD20 and DBA.44 stained 90% and 50% to 60% of hairy cells, respectively. Two of three cases of marginal zone lymphoma showed weak immunoreactivity to the TRAP antibody. Two specimens from a patient with Gaucher's disease and 8 of 13 cases of mastocytosis also showed positivity to the TRAP antibody in the macrophages and mast cells, respectively. In contrast, staining for DBA.44 was positive in 3 of 9 cases of B-cell large cell lymphoma, 1 of 4 cases of mantle cell lymphoma, and in the paraimmunoblasts of 1 of 7 cases of small lymphocytic lymphoma. Only HCL was TRAP and DBA.44 positive. This antibody to TRAP is a useful addition to the diagnosis of HCL but should be used in conjunction with CD20 and DBA.44. The use of this antibody to determine minimal residual disease after chemotherapy was not addressed.     

Gaucher's disease: the best laid schemes of mice and men

The creation of animal models of Gaucher's disease, the inherited deficiency of the enzyme glucocerebrosidase, has led to new clinical insights and to a new appreciation of the complexity of the glucocerebrosidase gene locus. Murine embryonic stem cells with targeted modifications in the glucocerebrosidase gene were used to generate mouse models of Gaucher's disease, the first having a null glucocerebrosidase allele. The resulting knockout mice have no glucocerebrosidase activity and die within 12 hours of birth. Ultrastructural studies of liver, spleen, brain and bone marrow demonstrate the characteristic storage material seen in Gaucher patients. In the nervous system, storage of lipid increased in a rostral-caudal distribution. Analysis of skin from the knockout mice revealed histological, ultrastructural and biochemical abnormalities. The null allele Gaucher mice are analogous to neonates with Type 2 Gaucher's disease who present with hydrops foetalis and/or congenital ichthyosis. Moreover, the epidermal changes seen in Type 2 mice are also found in Type 2 patients and may provide a means to presymptomatically discriminate Type 2 from Type 1 and 3 Gaucher's disease. Another targeted modification in the murine glucocerebrosidase gene locus led to the discovery of a contiguous gene, metaxin. Closer analysis of the glucocerebrosidase gene locus, including sequencing of 75 kb of genomic DNA, reveals that this is a gene-rich region coding for seven genes and two pseudogenes. Further study of these closely arrayed genes may contribute to our understanding of the clinical variation encountered among patients with Gaucher's disease.     

Plasma bone-specific alkaline phosphatase as an indicator of osteoblastic activity

The total plasma alkaline phosphatase level has long been recognised as an indicator of osteoblastic activity, but lack of specificity makes it an insensitive index of the progress of disease and the response to treatment. Selective precipitation by wheatgerm lectin allows measurement of the plasma bone-specific alkaline phosphatase. We measured the plasma levels of this isoenzyme in 170 normal Chinese adolescents and adults, in 49 adults with fractures of a long bone, in 15 patients with osteosarcoma and in 38 patients with osteolytic metastases. The enzyme activity was also determined in 39 patients with liver disease. Of the patients with fractures, 94% had increased plasma activity during the healing process. The level was also increased in those with osteosarcoma but not in those with osteolytic bone metastases. There was no significant increase in activity in the patients with liver disease. We conclude that the plasma bone-specific alkaline phosphatase activity is a sensitive and reliable measure of osteoblastic activity.     

Gaucher's disease: clinical features and natural history

Gaucher's disease is an inherited disorder characterized by pathological storage of glycolipid in mononuclear phagocytes: it is a multi-system disease associated with striking variation in its clinical manifestations, severity and course. Although molecular analysis of the glucocerebrosidase gene in patients with Gaucher's disease has permitted broad correlations between genotype and phenotype to be made, with few exceptions genetic variation at this locus does not allow confident prediction of clinical phenotype or prognosis. Partial deficiency of glucocerebrosidase is associated principally with parenchymal disease of the liver, spleen, bone marrow and, in severe cases, the lung, in non-neuronopathic, Type 1, Gaucher's disease: here storage material in macrophages originates from turnover of exogenous glycolipids. Severe deficiency of glucocerebrosidase caused by disabling mutations is additionally associated with neurological manifestations that in part reflect a failure to degrade endogenous neuronal glycosphingolipids, the so-called neuronopathic, Type 2 and Type 3 disease categories. Here we describe the clinical features, complications and natural history principally of Type 1 Gaucher's disease: emphasis is placed on emerging pulmonary, osseous and other manifestations of obscure pathogenesis that respond poorly to enzyme-replacement therapy.     

Enzyme replacement therapy for Gaucher's disease: the early Canadian experience

BACKGROUND: The management of severe Gaucher's disease was dramatically improved by the development of enzyme replacement therapy. However, this treatment is very costly (currently about $21,000 per infusion for adults at the starting dose recommended by the manufacturer). The goal of this study was to determine how enzyme replacement therapy was being prescribed and financially supported in various parts of Canada. In addition, demographic and outcome information was elicited. METHODS: Prescribing physicians were identified through professional associations and with the help of the manufacturer of the enzyme preparations used for the treatment of Gaucher's disease. The physicians were surveyed by questionnaire in July 1995. The study included all patients in Canada who had received enzyme replacement therapy for Gaucher's disease before July 1, 1995. RESULTS: A total of 25 patients (15 children and 10 adults) with type 1 Gaucher's disease, the common nonneuronopathic variant of the disease, were receiving enzyme replacement therapy by the end of 1995. The indications for treatment included massive splenomegaly, growth failure, and severe bony, hematologic and pulmonary complications of the disease; no patients with mild disease were receiving treatment. Treatment regimens varied markedly (from 12 to 160 units of enzyme/kg per month). All the patients were reported to have responded well to therapy, based on serial measurements of hematologic indices, liver and spleen volumes, and numbers of bony crises as well as patients' subjective impressions. Financial support for therapy varied markedly from one province to another. None of the reporting physicians was aware of any patients with severe Gaucher's disease who were denied therapy as a result of inability to pay for the medication. Various agencies provided financial support for therapy, including both federal and provincial governments, private insurance carriers and the commercial supplier of the enzyme. In Ontario provincial health care officials accepted the development, by a multidisciplinary panel of medical experts, of formal guidelines for determining eligibility, on the basis of objective medical criteria, for reimbursement for enzyme replacement treatment. INTERPRETATION: Although some differences were found across the country with respect to the details of treatment, the indications for enzyme replacement therapy and the selection of severely affected patients were similar in the various provinces. However, financial support was inconsistent and varied among provinces and patients. This will prove to be a challenge in future, not only with respect to this disease but also for other diseases for which effective, expensive therapy has been developed.     

Alkaline phosphatases in tissues and sera of cats

The numbers and widths of bands of alkaline phosphatase (ALP) activity in polyacrylamide gels and the comparison of their electrophoretic mobility to that of a reference substance (Rf value) were found to be reliable aids in the identificaiton of various isoenzymes in in serum and organ extracts from cats. The hepatic isoenzyme was identified in sera of clinically normal adult cats, pregnant cats late in gestation, and cats with common bile duct occlusion. In addition to the hepatic isoenzyme, placental ALP was found late in gestation in sera from queens. Sera from kittens less than 15 weeks of age contained only the osseous ALP isoenzyme.     

Isoenzymes of membrane-bound beta-glucosidase of human spleen

Normal human spleen contains two forms of membrane-bound beta-glucosidase, distinguishable by their thermostability and kinetic properties. The spleen from a patient with adult Gaucher's disease was deficient in the major, thermolabile, form of the enzyme.     

Studies on photodegradation of vitamin K1. I. Determination of vitamin K1 by gas-liquid chromatography (author''s transl)

Glucosyl sphingosine was isolated from the spleen of a patient with adult-type Gaucher's disease. The yield of purified glucosyl sphingosine was 9.3 nmoles/g wet tissue. The gas chromatography-chemical ionization mass spectrum of acetylated glucosyl sphingosine showed peaks due to the presence of ions formed by successive loss of acetic acid (mass 60) from the molecular ion (QM+, 714). Fragments from acetylated sugar, m/e 331, and from the sphingosine residue, m/e 306, were also detected. The GC-CI mass spectrum of the trimethylsilyl derivative of glucosyl sphingosine showed peaks due to the molecular ion (QM+, 822), ions from the sugar moiety (m/e 361, 271), and ions from the sphingosine base (m/e 264, 280). Fragmentation analysis of the purified sample by GC-EI and GC-CI mass spectrometry confirmed the structure glucopyranosyl(1 leads to 1)-1,3-dihydroxy-2-amino-4-octadecene.     

Congenital stricture of male urethra

It was intendet to characterize the isoenzymes of serum alkaline phosphatase in healthy infants. Quantitative estimation of the activity of serum alkaline phosphatase resulted in relatively low values in the newborns and a distinct increase during the first three months of live. As a rule most of the newborns appeared to present one uniform isoenzyme fraction, which was comparable to the isoenzyme of bone origin of the adult. Some of the newborns already exhibited another less marked isoenzyme, the isoenzyme of liver origin. During babyhood this isoenzyme becomes more and more distinct. In most cases this development had become perfect at the end of the first year. Liver tissue of newborns apparently does not synthesize the same liver isoenzyme as liver tissue of adults.     

Effect of the levonorgestrel-releasing intrauterine system on the uterine artery pulsatility index in postmenopausal hormone replacement therapy

Previous studies have demonstrated a significant reduction of N-methyl-D-aspartate (NMDA) receptor binding in spinal cord sections from patients who died with amyotrophic lateral sclerosis (ALS) compared to that in control patients. The reduction in NMDA receptor binding in ALS could be increased toward control values by treatment with phorbol ester, suggesting a role for receptor protein phosphorylation in this disorder. In the present study we have evaluated the time course of recovery of [3H]MK-801 binding following phorbol ester treatment to assess protein phosphatase activity in spinal cord sections from ALS and control subjects. Phorbol ester-stimulated changes in [3H]MK-801 binding returned to untreated values significantly faster in ALS tissue compared to control and could not be blocked by the coapplication of the protein phosphatase inhibitors sodium vanadate or sodium beta-D-glycerol phosphate. Okadaic acid coapplication blocked recovery in both ALS and control tissue at a concentration range at which phosphatase 2B (calcineurin) would likely be inhibited. The results suggest that abnormal levels or activity of protein phosphatases, including calcineurin, may be involved in the abnormal levels of NMDA receptors in ALS and may play some role in the pathogenesis of the disease.     

Study on neutrophil enzymes in atopic disease

Neutrophils (PMN) from 20 patients with atopic disease (atopy), the parents of 8 of the patients and 10 normal controls were studied by light-microscopic cytochemistry. The results revealed that myeloperoxidase (MPO) and acid phosphatase (ACP) activities in PMN in all cases significantly decreased and alkaline phosphatase activity was normal. Parents or parent of 7 of those patients had PMN enzyme deficiency similar to that of the patients. The results indicated that a primary combined and partial deficiency of MPO and ACP in PMN azurophilic granule existed in atopy. It is postulated that the deficiency led to reduction of PMN bactericidal power and delay of bactericidal action. Foreign bodies which were partially degraded could possess antigenic property. This is believed to be the important cytobiological mechanism of the tendency toward infections and formation of sensitive antigen in atopy.     

Increased basal glucose production in type 1 Gaucher's disease

To evaluate the metabolic effects of Gaucher's disease, glucose metabolism and parameters of fat metabolism were studied by indirect calorimetry and primed continuous infusion of [3-3H]glucose in seven clinically stable untreated patients with type 1 Gaucher's disease and in seven healthy matched control subjects. Studies were performed in the postabsorptive state. In Gaucher patients, resting energy expenditure was increased by approximately 24% (29.4 +/- 0.7 vs. 23.7 +/- 0.8 kcal/kg.day; P < 0.01). Glucose production was increased by approximately 30% in patients compared to controls (14.00 +/- 0.51 vs. 10.77 +/- 0.26; P < 0.01), although plasma glucose concentrations and net glucose oxidation were not different. Although C peptide concentrations were not different, insulin concentrations were slightly increased in Gaucher patients (P < 0.05). The differences in basal glucose production were not related to differences in plasma concentrations of insulin or other glucoregulatory hormones. In conclusion, the increase in basal glucose production is a remarkable feature of type 1 Gaucher's disease, which cannot merely be explained by endocrine mechanisms. Because Gaucher's disease is manifested within the liver in macrophages, but not in hepatocytes, altered intrahepatic regulatory mechanisms might be involved in this increase in glucose production.     

Antigen retrieval in cryostat tissue sections and cultured cells by treatment with sodium dodecyl sulfate (SDS)

BACKGROUND: Steroid 5 alpha-reductase is essential for the intracellular accumulation of dihydrotestosterone (DHT), which mediates androgen effects on target tissue. METHODS: In the present study, we describe the differential expression and cellular localization of 5 alpha-reductase 1 and 2 isoenzymes in the human prostate, and untreated and hormone-resistant prostatic carcinomas. The secretory epithelium of normal and hyperplastic glands showed strong nuclear 5 alpha-reductase 1 reactivity. Accordingly, the DHT forming 5 alpha-reductase process in secretory luminal cell types may be mediated predominantly by the type 1 isoenzyme. The androgen-independent basal cell layer variably expressed type 1 and 2 isoenzymes in nuclear and cytoplasmatic compartments. This suggests that circulating androgens are involved to control the basal cell layer, which represents the proliferative compartment of the human prostate. RESULTS: When compared with benign prostate tissue, increased 5 alpha-reductase reactivity was detected in prostate cancer, particularly in high-grade tumors and androgen-insensitive states of the disease. In cancerous lesions, the type 1 isoenzyme tended to shift to the cytoplasm, while the nuclear staining remained unchanged or slightly increased. Referring to the type 2 isoenzyme, increased cytoplasmatic and nuclear enzyme activity was detected in malignant cells when compared with adjacent benign prostate tissue. Even endocrine differentiated tumor cells that consistently lacked the nuclear androgen receptor variably expressed 5 alpha-reductase immunoreactivity. CONCLUSIONS: Although the functional significance of the differential subcellular localization of type 1 and 2 isoenzymes is currently unknown, the present data suggest that prostate cancer retains the DHT forming 5 alpha-reductase process in high-grade lesions and recurrent disease. Accordingly, circulating androgens may be still significant in these hormone-refractory malignancies.     

Hypophosphatasia: a developmental anomaly of alkaline phosphatase?

This report deals with quantitative and qualitative investigations of alkaline phosphatase in two unrelated infants with the severe infantile form of hypophosphatasia. Both affected infants had no detectable leukocyte alkaline phosphatase activities and both sets of parents and one sibling tended to have low but variable leukocyte enzyme activities. Normal duodenal juice alkaline phosphatase activity was present in the one patient in whom it was measured and a wide range of variation in enzymic activity was observed in the stools. There was no significant difference in the stool enzyme activity between both patients with hypophosphatasia (42.01 +/- 9.77 U) and control infants (40.55 +/- 6.29 U). However, the heterozygous parents had values significantly lower than the control adults (2.10 +/- 0.47 as compared with 19.10 +/- 4.44 U). Intestinal bacteria did not contribute significantly to the stool alkaline phosphatase activity. Enzyme activity was present in the bile of one of the patients and nearly absent in that of the other. Three "inducers" of alkaline phosphatase were given to both patients (phenobarbital, vitamin A, and corticosteroid). No clinical improvement or rise in serum alkaline phosphatase activity was observed during the trial of therapy with these agents. However, a significant increase in the activity of serum acid phosphatase was demonstrated during the course of vitamin A administration, suggesting an in vivo action of vitamin A on the lysosomes through decreasing the stability of the membrane and releasing acid phosphatase to the serum. Quantitative determination of tissue alkaline phosphatases from autopsy tissues was highly variable: no activity was found in bone, lungs, or spleen of either infant; there was a discrepancy in liver and kidney alkaline phosphatase values (zero in one patient and present in the other) and activity was present in the intestinal mucosa of both. Qualitative analysis of kidney, liver, and intestinal alkaline phosphatase revealed some differences between the patients and control subjects in heat inactivation and phenylalanine inhibition (Table 3). Starch gel electrophoresis of the liver preparation of one patient disclosed a single band which had greater mobility than that of six control subjects matched for age. Liver extracts from a premature and from full term newborns showed two bands. The single band of the patient's liver enzyme corresponded to the newborn's fast moving component. In addition, the intestinal enzyme prepared from the same patient had an extra band when compared with age-matched control subjects.     

Development of Purkinje cells in absence of climbing fibers

A fresh spleen sample obtained from a patient with leukemic reticuloendotheliosis was homogenized and subjected to centrifugation on a sucrose density gradient. A major portion of acid phosphatase band 5 was observed in the lysosome, confirming that the elevated phosphatase activity in the neoplastic spleen is a lysosomal enzyme. However, a significant amount of brand 5 was also observed in the microsome. The microsomal and lysosomal enzymes have different affinity to CM-cellulose. The relationship between lysosomal and microsomal enzymes has not been established.     

Serum activities of hydroxybutyrate dehydrogenase (HBD) and the isoenzymes of lactate dehydrogenase (LD) as an index of traumatic brain injury

The lactate dehydrogenase (LD), the hydroxybutyrate dehydrogenase (HBD), and the LD isoenzyme activities in serum were followed in the posttraumatic period in 113 patients with cranio-cerebral injury, 70 of whom had verified brain contusion--laceration. In patients with brain contusion the HBD activity, known to be exerted mainly by the anodal LD isoenzyme fractions dominating in brain tissue, was significantly raised in 91% of the blood samples taken within four hours, and in 92% of the samples taken between 12 and 24 hours after trauma, while it was within normal limits in all the samples taken within four hours in patients with brain concussion, and increased in only 17% of the concussion patients 12-24 hours after trauma. The LD1 and the LD1+2 activities were of less diagnostic importance in blood samples taken during the first 24 hours. However, after 24 hours the LD1 activity was as informative as the HBD activity. The LD1 activity was normal in all concussion patients from the third day after trauma, while 78% of the contusion patients still showed raised LD1 activity then. The determination of HBD activity in serum in the immediate post-traumatic period is recommended as an appropriate method for screening parenchymatous brain injury. A complete LD isoenzyme separation may later add some further information in doubtful cases.     

Thiobarbituric acid reactive substances are increased in the subcutaneous fat tissue of patients with end-stage renal disease

BACKGROUND: Patients with end-stage renal disease are thought to be in a highly peroxidative state, based on studies showing decreased serum antioxidant activity and increased peroxidative products. In this study we confirm these findings by examining lipid peroxidation in subcutaneous fat tissue in uraemia. SUBJECTS AND METHODS: Twenty-seven subcutaneous fat samples were taken from patients with end-stage renal disease when they underwent intervention for arteriovenous fistula for haemodialyis or for catheter insertion for continuous ambulatory peritoneal dialysis. The control samples were taken from 11 patients with normal renal function and without any history of renal disease who had surgical interventions. Lipid peroxides were measured as thiobarbituric acid reactive substance. RESULTS: The concentration of thiobarbituric acid reactive substances in subcutaneous fat tissue in the patients with end-stage renal disease is 1.223 +/- 0.636 nmol/mg fat tissue (mean +/- SD) whereas the level in the control group is 0.097 +/- 0.054 nmol/mg fat tissue. A comparison of the two groups by Student's t test revealed a highly significant difference (P < 0.001). CONCLUSIONS: This study supports the finding of a severe peroxidative state in patients with end-stage renal disease.