Studies on the action of some anti-inflammatory agents in inhibiting the biosynthesis of mucopolysaccharide sulphates

ON THE SITE OF SULFATION IN THE CHONDROCYTE

As observed autoradiographically in the cartilage of embryonic rats, radiosulfate is bound and concentrated only in vesicles of the juxtanuclear Golgi apparatus of secreting chondrocytes within 3 minutes of its presentation. From this area, vacuoles migrate peripherally and lodge in the subcortex; their sulfated contents are thence discharged via stomata to the extracellular matrix. The label, apparently often associated with microvesicles at 10 and 20 minutes, is subsequently localized in the dense contents of the larger vacuoles. Bound radiosulfate is not detectable in other organelles. It is concluded that the vesicular component of the Golgi apparatus is the actual site of sulfation. Intracellular hyaluronidase-sensitive metachromatic granules are found chiefly at the cell periphery or mantle, rarely juxtanuclear in the main Golgi zone.

ON THE SITE OF SULFATION IN COLONIC GOBLET CELLS

The location of bound S³⁵ in the goblet cell of the rat colon at time points from 2 to 60 minutes after administration of S³⁵ as sodium sulfate has been observed in vivo and in vitro by radioautographic techniques. Grains were first observed by electron microscopy over the stacked lamellae of the paranuclear part of the Golgi apparatus. The label was subsequently found associated with the supranuclear Golgi lamellae and was then seen associated with the smooth membranes limiting the mucin granules in the goblet. Finally, between ½ and 1 hour, the secreted mucus product in the crypts became radioactive. Neither mitochondria nor the endoplasmic reticulum was labeled. It is concluded that the Golgi apparatus is the organelle in which sulfation occurs.

The effect of chronic paracetamol administration to rats on the glycosaminoglycan content of patellar cartilage

Male Wistar rats were treated with paracetamol (200 mg/kg twice a day) for 2, 3, 4 and 9 weeks. During the first four weeks of paracetamol administration the serum sulfate concentration was significantly decreased. However, during the fourth until the ninth week, the serum sulfate concentration was only diminished to a small and insignificant extent. The paracetamol administration did not lead to serious liver or renal toxicity, as determined by alanine aminotransferase and creatinine levels in the serum of the rats. The paracetamol-induced serum sulfate depletion, observed during the first four weeks of the experiment, led to a significantly lower glycosaminoglycan content of the patellar cartilage of the rats after three and four weeks paracetamol treatment. When after the fourth week the serum sulfate concentration rose to nearly normal levels also the glycosaminoglycan content in the rat patellar cartilage reached control levels. These data indicate that the serum sulfate depletion might be the causative factor for the observed reduction in glycosaminoglycan content of rat patellar cartilage.

Inhibition of glycosaminoglycan synthesis in anatomically intact rat patellar cartilage by paracetamol-induced serum sulfate depletion

We have studied the effect of low sulfate concentrations on the glycosaminoglycan synthesis in rat patellar cartilage in vivo as well as in vitro. The oral administration of 200 mg/kg paracetamol to male Wistar rats resulted in a significant reduction of the serum sulfate concentration. Reduced serum sulfate availability resulted in a 34% decrease of glycosaminoglycan synthesis in patellar cartilage. This is due to sulfate depletion since paracetamol had no direct effects on glycosaminoglycan synthesis and a slight but significant inhibitory effect on the catabolism of radiolabeled glycosaminoglycans in vitro. The glycosaminoglycans synthesized at low sulfate concentrations in vivo were similar to the glycosaminoglycans synthesized at physiological sulfate concentrations. Studying the effect of sulfate availability in vitro on glycosaminoglycan synthesis in patellar cartilage we found that incubation of rat patellae in medium containing less than 0.5 mM inorganic sulfate led to a decreased sulfate incorporation. The use of potential sulfate decreasing drugs can lead to inhibition of glycosaminoglycan synthesis. This argues for a reconsideration of the use of these drugs in patients with already dysfunctioning cartilage metabolism as in rheumatoid arthritis and osteoarthrosis.

Effects of NSAIDs on the metabolism of sulphated glycosaminoglycans in healthy and (post) arthritic murine articular cartilage

Several non-steroidal anti-inflammatory drugs (NSAIDs) were studied for their effects on normal and damaged murine articular cartilage, both in vitro and in vivo. In vitro, in the absence of serum, sodium salicylate caused significant suppression of 35S-glycosaminoglycan (GAG) synthesis, whereas tiaprofenic acid, piroxicam, prednisolone sodium phosphate and several other NSAIDs were without effect. Trypsin-mediated proteoglycan depletion did not change the susceptibility of the articular chondrocyte to these drugs. Similarly, no enhancement of drug effect was seen when arthritic cartilage was taken from an acutely inflamed joint, and prenisolone sodium phosphate even seemed to diminish inflammation-mediated suppression of 35S-GAG synthesis. The short term in vivo effects of some of the drugs were tested in mice with unilateral zymosan-induced arthritis. At day 1 after arthritis induction, in vivo 35S-GAG synthesis by the cartilage of the arthritic joint was decreased to 63%. Only sodium salicylate suppressed in vivo 35S-GAG synthesis in the healthy and arthritic joint to the same extent in both. At day 28, GAG synthesis in the postarthritic joint was enhanced to 160%. This type of cartilage appeared to be more susceptible to drug effects, since all drugs tested showed clear suppression of the augmented GAG production in vivo. Finally, in vivo drug effects were tested on normal and enhanced 35S-GAG degradation, the latter in the zymosan-induced arthritic joint. Both tiaprofenic acid and prednisolone sodium phosphate appeared to suppress degradation in healthy and, to some extent, in arthritic cartilage.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of O-acetylsalicylic acid on lipid synthesis by guinea pig gastric mucosa in vitro

The aim of this work was to investigate the involvement of lipids as possible components of the gastric mucosal barrier by studying the synthesis and secretion of lipids by the epithelial cell lining of gastric mucosa and the effect of salicylate on these processes. O-Acetylsalicylic acid reversibly reduced in vitro incorporation of [U-14C]acetate and of DL-[2-14C]mevalonic acid into lipids by isolated epithelial cells and by intact mucosa of guinea pig stomach, indicating reversible inhibition of lipid synthesis by the tissue in the presence of the drug. Inhibition of incorporation of both precursors into total lipids, into their fatty acid components, and into cholesterol is demonstrated.

Glucocorticoids change the nucleotide and sugar nucleotide pool sizes in cultured human skin fibroblasts

Fibroblasts in culture were treated with the glucocorticoid budesonide. The nucleotide and sugar nucleotide pools were quantitated after separation by isotachophoresis. Steroid treatment induced a 40% increase of the UDP-N-acetylhexosamine pool and a 30% increase of the UDP-glucuronic acid pool whereas the UTP pool was diminished. These effects became apparent after 24 h of incubation and a new steady state was attained after 48 h of incubation. The 3'-phosphoadenosine-5'-phosphosulfate pool was probably not influenced by the glucocorticoid treatment. The half-life of the UDP-N-acetylhexosamine pool was considerably longer in treated than in control cells. The efflux from the UDP-N-acetylhexosamine pool was also lowered in the treated cells. The changed efflux may be due to a decreased glycoconjugate synthesis induced by glucocorticoid treatment. The rate of equilibration of [14C]glucose and [3H]glucosamine with the UDP-N-acetylhexosamine pool was changed by glucocorticoid treatment; especially that of [3H]glucosamine was decreased.

Inhibition of mucopolysaccharide sulfation using rabbit liver sulfotransferases

A method of measuring the inhibition of sulfation of mucopolysaccharides employed the coupled-enzyme system of Wortman. The procedure utilized the phenol and mucopolysaccharide sulfotransferases of rabbit liver extract. Compounds tested as inhibitors included substituted salicylic acids and related compounds, some hydroxamic acids, other agents capable of metal-ion complexation, and miscellaneous compounds, mostly containing sulfur. The most effective inhibitors were vanillin oxime, salicylhydroxamic acid, and other substituted salicylic acid derivatives of weaker acid strength than salicylic acid.

Inhibition of mucopolysaccharide sulfation

A method of measuring the inhibition of sulfation in mucopolysaccharides employed the coupled enzyme system of Wortman. This procedure utilized the phenol and mucopolysaccharide sulfotransferases of beef cornea extract. Compounds tested against this system included amino acids, salicylates, 2-mercaptoethylamine and a derivative, heterocyclic ethanethiosulfuric acids, arylsulfonamidoethanethiosulfates, and several other compounds. In general, the salicylates and thiosulfates were inhibitory, with sodiumm 2-(4-acetamidobenzenesulfonamido)-ethanethiosulfate being the most inhibitory and 2-mercaptoethylguanidine trithiocarbonic acid the second most inhibitory. Salicylamide and allopurinol, which have been employed in kidney stone therapy, were inhibitors. Kidney stones have a mucopolysaccharide sulfate matrix, which is involved in their growth.

Effects of potassium para-aminobenzoate on growth and macromolecule synthesis in fibroblasts cultured from normal and sclerodermatous human skin, and rheumatoid synovial cells

Potassium para-aminobenzoate was tested for its ability to affect growth and macromolecule synthesis in vitro using fibroblasts from normal human skin, from affected skin of patients with scleroderma, and rheumatoid synovial cells. The proliferation of all 3 cell types showed dose-dependent inhibition beginning at about 3000 microgram/ml. Acid mucopolysaccharide secretion by rheumatoid synovial cells and scleroderma fibroblasts was inhibited even at 100 microgram/ml, which is within the therapeutic range, and there was over 50% inhibition at 5000 microgram/ml. Collagen synthesis by several different strains, was not affected, despite the use of a range of concentrations and treatment times.

Salicylate- and aspirin-induced uncoupling of oxidative phosphorylation in mitochondria isolated from the mucosal membrane of the stomach

The hypothesis that the damaging effect on the stomach mucosa of salicylic acid and its derivatives is ascribable to an uncoupling of oxidative phosphorylation has been investigated by testing of mitochondria isolated from the corpus gland area of mini-pig gastric mucosa. Mitochondria, influenced by salicylate or acetylsalicylate (0.7-5.6 mmol/l), demonstrated increased respiration rate, decreased respiratory control ratio, and decreased P/O ratio when tested in vitro. Uncoupling of oxidative phosphorylation occurred at a salicylate concentration between 3.5 and 5.6 mmol/l.

Alteration of tumor growth by aspirin and indomethacin: studies with two transplantable tumors in mouse

Oral daily administration of aspirin or indomethacin retarded growth of experimental tumors in mouse. Aspirin treatment, 150 mg/kg twice daily, inhibited growth of a transplantable mast-cell ascites tumor (P815) by 39-43% (p less than 0.001) and of a s.c. transplanted Lewis lung carcinoma by 52% (p less than 0.025) without adversely affecting body growth. The total serotonin, histamine and histidine decarboxylase content of the ascites tumor was also reduced as was the urinary excretion of the amines. Treatment with 3 and 5 mg/kg indomethacin resulted in 40% (p less than 0.01) and 80% (p less than 0.001) reduction, respectively, in ascites tumor growth. With the higher dose of indomethacin, no tumor was observed in half of the animals inoculated with tumor, although signs of indomethacin toxicity (reduced body growth, gastric lesion) was evident in the animals.

Some aspects of corticosteroid-induced cleft palate: a review

Since the discovery 25 years ago that cortisone can produce cleft palate in mouse embryos investigations into possible mechanisms of this corticosteroid-induced defect have been many and varied. However, the teratogenic mode of action remains not fully clarified. It is with this thought in mind that we have reflected upon what is known concerning corticosteroids and cleft palate. The major metabolic pathways upon which glucocorticoids act as well as their intracellular mode of action are well known. Differential sensitivity of various mouse strains to cortisone treatment as well as recent results from interstrain blastocyst transfer experiments demonstrate that corticosteroid action is influenced by both the fetal and maternal genomes. Labeling experiments indicate that corticosteroid-induced cleft palate is the result of direct action of the steroid molecule on the fetus, whose own sensitivity to insult, perhaps owing to differences in binding of corticosteroids to tissue proteins, determines the final effect. Possible mechanisms that have been proposed by which corticoids may produce cleft palate include: disruption of glycosaminoglycan or collagen synthesis or both, intracellular lysosomal membrane stabilization, myopathy, weakened midline fusion, and loss of amniotic fluid. Also discussed is the role of stress and stress-induced corticosteroids and their possible role in the production of cleft palate.

Vitamin A and the biosynthesis of sulphated mucopolysaccharides. Experiments with rats and cultured neoplastic mast cells

1. The uptake and incorporation of [(35)S]sulphate into mucopolysaccharides by colon and duodenum in vitro are unaffected by the vitamin A status of the animals. 2. Uptake and incorporation in vivo are unaffected at 4hr. after injection of [(35)S]sulphate, but at later times are decreased in some tissues of vitamin A-deficient animals. 3. The rate of removal of (35)S from blood, its rate of appearance in urine, the plasma concentration of sulphate and the uronic acid content of several tissues are not significantly altered in vitamin A deficiency. 4. These results, and direct measurement of (35)S in mucopolysaccharides at various times after injection of [(35)S]sulphate, suggest that the synthesis of mucopolysaccharides is unaffected but that their turnover is increased in vitamin A deficiency. 5. Neither the growth rate of, nor the incorporation of [(35)S]sulphate into heparin by, P815Y and HC cultured neoplastic mast cells is decreased when the horse serum necessary for growth is treated with ultraviolet light or is replaced by serum from vitamin A-deficient rats. 6. The addition of citral is no more toxic to growth rate or to incorporation of (35)S than is the addition of vitamin A itself. 7. It is concluded that neoplastic mast cells in culture do not require vitamin A for growth or for the synthesis of heparin. 8. None of these results is compatible with the view that vitamin A or a derivative is directly involved in the biosynthesis of sulphated mucopolysaccharides.

The biosynthesis of intestinal mucins. The effect of salicylate on glycoprotein biosynthesis by sheep colonic and human gastric mucosal tissues in vitro

1. Incubation of sheep colonic mucosal scrapings in Krebs-Ringer buffer for 2(1/2)hr. in the presence of salicylate (15mm) resulted in decreased incorporation of radioactivity into the epithelial glycoprotein from the following labelled precursors: 16.6mum-d-[2-(14)C]glucose (83.9% inhibition), 20mum-l-[U-(14)C]threonine (82%) and (35)SO(4) (2-)(79%). Oxygen uptake measured simultaneously was diminished to 41% of the control value. 2. At lower concentrations of salicylate (e.g. 3.75mm), incorporation of 20mum-l-[U-(14)C]threonine was little affected (3-6% inhibition), whereas utilization of 4mum-d-[U-(14)C]glucose and (35)SO(4) (2-) was inhibited (41-48% and 40-59% of the control values respectively). 3. Analysis of the papain-digested glycoprotein from tissue incubations with 16.6mum-d-[2-(14)C]glucose in the presence of salicylate (3.75mm) showed large decreases in labelling of N-acetylneuraminic acid and N-glycollylneuraminic acid residues (57% and 34% of the control values respectively) and of hexosamine constituents (glucosamine, 55% inhibition; galactosamine, 33% inhibition). Labelling of neutral sugars (galactose and fucose) was relatively little affected (9 and 11% inhibition respectively). 4. Glucose 6-phosphate transaminase and glucosamine 6-phosphate acetylase in particle-free enzyme preparations of the sheep tissue were unaffected by salicylate at the above concentrations. Acetyl-CoA synthetase was markedly inhibited. 5. Human gastric mucosa (from operation), on incubation as above, had in one experiment an oxygen consumption of 9.9mul./hr./mg. dry wt. of tissue and incorporated 5mum-d-[U-(14)C]glucose (15.8% of the total radioactivity added) into bound hexosamine (20.6% of the total radioactivity incorporated), hexoses (glucose and galactose, 5.7%) and fucose (14.2%). The presence of salicylate (15mm) decreased the incorporation of 5mum-d-[U-(14)C]glucose into the glycoprotein by 74%, all sugar constituents being affected, without influence on the rate of oxygen consumption. 6. The results suggest an inhibitory effect of salicylate on glycoprotein biosynthesis at the level of the amino sugar intermediates.

Study of the Hurler syndrome using cell culture: definition of the biochemical phenotype and the effects of ascorbic acid on the mutant cell

Fibroblasts from patients with Hurler syndrome retain a distinctive biochemical phenotype when grown in culture which is characterized by increased synthesis of both nonsulfated and sulfated glycosaminoglycans. Ascorbic acid reinforces the phenotypic expression of the biochemical abnormality, producing not only increased synthesis of sulfated glycosaminoglycans, but selective retention of sulfated glycosaminoglycans within the cell. Although the synthesis of nonsulfated glycosaminoglycans is also increased, these compounds, particularly hyaluronic acid are not retained by the cell but are secreted into the medium. Analyses of urine from patients with Hurler syndrome show increased absolute concentrations of nonsulfated glycosaminoglycans in addition to the expected increase in sulfated glycosaminoglycans. This indicates that the biochemical phenotype as defined in cell culture is not an artifact of the experimental model but reflects the biochemical defect in the patient. Redefinition of the biochemical defect to include nonsulfated as well as sulfated glycosaminoglycans contradicts explanations of this disease which are based on a single structural gene mutation.

Ascorbic acid deficiency in cultured human fibroblasts

Fibroblasts grown in medium containing less than 1 microg of ascorbic acid per milliliter showed evidence of ascorbic acid deficiency when compared with cells grown in medium containing 50 microg of ascorbic acid per milliliter. This was manifested morphologically by dilated endoplasmic reticulum, a decrease in number, size, and intensity of staining of the mitochondria, by defective intercellular fibril formation, and by easy disaggregation of the cells from the intercellular matrix after treatment with pronase. When 50 microg per milliliter of ascorbic acid was incorporated into the medium, the altered morphology was corrected, banded fibrils were produced which were organized into bundles, and the cells were tightly bound in a matrix which was resistant to disaggregation with a variety of proteolytic enzymes. Collagen and sulfated glycosaminoglycan synthesis were less in the control than in the ascorbic acid supplemented cells. Similar morphological and chemical changes have been reported in the connective tissue of scorbutic animals. The effects of low ascorbic acid concentration on fibroblasts in culture indicate that these cells require ascorbic acid to maintain connective tissue functions.