Lysosomal enzyme variations in cultured normal skin fibroblasts

Collagen deposition in autoimmune diseases: the expanding role of the fibroblast in human fibrotic disease

Fibrosis, usually considered an extension of the normal process of wound healing, follows to a variable degree host responses of an inflammatory nature, both immune and non-immune. The immediate mesenchymal effector cell of fibrosis, the fibroblast, has more or less been taken for granted in this process, due largely to its monotonous morphological uniformity. An emerging realization that the fibroblast can react in a variety of ways, both as an amplifying population of cells and in selective ways as the final arbiter of the extracellular matrix, is the subject of this report. This heterogeneity of fibroblast behaviour is characterized and, since many types of cells (endothelial, smooth muscle, epithelial) have now been shown to respond to matrix-derived signals, the potential for mesenchymal cell selection as a mechanism for understanding human fibrotic disease is probed. Signals which selectively alter fibroblast proliferation and fibroblast phenotypic expression are emphasized.

Influence of alcohol and tobacco habits on peri-implant marginal bone loss: a prospective study

A prospective clinical study was conducted to explore the possible link between peri-implant bone loss and the widespread habits of tobacco smoking and alcohol consumption. One hundred and eighty-five patients who received 514 implants were followed up for 3 years. Peri-implant marginal bone loss was evaluated by digital panoramic radiography and image analysis techniques. Multivariate analysis showed that peri-implant marginal bone loss was significantly related to a daily consumption of >10 g of alcohol, tobacco use and increased plaque levels and gingival inflammation. The present results indicate that daily alcohol consumption and tobacco use may have a negative influence on predictable long-term implant treatment outcomes, producing peri-implant bone loss and compromising restorative treatment with implant-supported prostheses.

Effects of nicotine on proliferation and extracellular matrix production of human gingival fibroblasts in vitro

Normal function of gingival fibroblasts is essential for maintenance of the gingival extracellular matrix (ECM), but under inflammatory conditions in gingival tissue which may occur with tobacco use, they can also act in its destruction. The purpose of this study was to determine the effects of nicotine, a major component of tobacco, on gingival fibroblast proliferation, the production of fibronectin (FN), and the production and breakdown of type I collagen to elucidate its role in periodontal destruction associated with its use. A human gingival fibroblast strain derived from a healthy individual with non-inflamed gingiva was used in this study. Nicotine at concentrations > 0.075% caused cell death, and at 0.075% and 0.05% it caused transient vacuolization of the fibroblasts. At concentrations of 0.001% to 0.075%, nicotine significantly inhibited proliferation (P < or = 0.03), measured by the incorporation of [3H]-thymidine into DNA. The production of FN and type I collagen was significantly inhibited by nicotine at > or = 0.05% (P < or = 0.001), measured using specific ELISAs. On the other hand, nicotine at > or = 0.025% significantly increased collagenase activity (P < or = 0.008), using [3H]-gly and [14C]-pro-labeled type I collagen gels as substrate. The results show that, in vitro, nicotine inhibits the growth of gingival fibroblasts and their production of FN and collagen, while also promoting collagen breakdown. This suggests that nicotine itself may augment the destruction of the gingival ECM occurring during periodontal inflammation associated with smokeless tobacco use.

Comparisons of morphology and growth rate between cells from skin biopsies of schizophrenic patients and those from normal individuals

Skin biopsies have been used to establish cell cultures from ten schizophrenic individuals and ten controls. Studies of the time of outgrowth of different cell types from the tissue fragments and the subsequent growth rates and morphology showed no difference between the primary cultures from the schizophrenic patients and controls. The primary cultures were trypsinized and grown for three passages before storing in liquid nitrogen. No difference between cell strains established from schizophrenic skin donors and cell strains from healthy controls was noted in this phase of growth. Aliquots of cells were thawed out from liquid nitrogen, grown for one passage and then the cell aggregation rate was tested. No difference was found between cells from schizophrenic skin donors and cells from controls. Differences between the two cell strains established from certain individuals did occur, suggesting that morphology and growth rates should be noted before cell strains are used for further studies.

Heterogeneity of fibroblasts derived from human free and attached gingiva. Glycosaminoglycan synthesis and effects of phenytoin (PHT) treatment

Two fibroblast populations derived from free and attached gingiva (FGF, AGF) have been compared in cell culture. They exhibited the same morphology and similar cytoskeletal staining patterns, but were different in glycosaminoglycan (GAG) synthesis. FGF released larger quantities of GAGs than AGF in the medium. The extracellular accumulation of hyaluronic acid was higher in FGF than in AGF, whilst the reverse pattern was observed intracellularly. In the case of sulphated GAGs the extracellular concentration, compared to HA, was higher in AGF, while the intracellular concentration was higher in FGF. The two cell populations responded differently to phenytoin (PHT) administration. PHT treatment increased the proportion of intracellular sulphated GAGs in AGF and of extracellular sulphated GAGs in FGF.

Immunocytochemical and biochemical characterization of the connective tissue component of fibrous papular lesions of oral mucosa

In an attempt to define the fibroblastic components of fibrous papular lesions of oral mucosa, 21 cases representing these lesions were selected for study. Paraffin or frozen sections of the lesions were stained, using the immunoperoxidase technique, with antibodies to: alpha-l-antitrypsin, alpha-l-antichymotrypsin, lysozyme, fibronectin, actin, myosin, and for Clq binding. Three of these cases were biochemically analyzed for collagen Types I, III, and V. This study demonstrated the presence of cytochemical markers in fibrous papules that were similar to those observed for the compartment of circumvascular fibroblasts in control normal mucosa. Analysis of the collagens present indicated that in addition to histologic similarities, the gene products of these extracellular matrices were similar to those reported for angiofibromas and Shagreen patches in tuberous sclerosis. The cells in these lesions appear to be distinct from myofibroblasts and the high affinity complement binding fibroblasts characterized by Bordin et al.(1).

Reversible change in the fibroblast lysosomal enzyme dipeptidyl aminopeptidase-1 (cathepsin C) related to the commercial source of fetal bovine serum in the culture medium

The commercial source of fetal bovine serum used to supplement the growth medium of human skin fibroblasts alters the activity of the lysosomal enzyme dipeptidyl aminopeptidase-1 (DAP-1). Cells grown with one serum were found to have a threefold higher level of DAP-1 than those grown with serum from another source (P less than 0.001). The effect on DAP-1 activity was specific inasmuch as no differences were found in the activities of a variety of other lysosomal and nonlysosomal hydrolases: DAP-II, DAP-III, DAP-IV, beta-glucosidase, beta-glucuronidase, and N-acetyl-beta-galactosaminidase. The effect is reversible and is observed over a wide range of cell population doublings. Cell growth kinetics were not significantly different with the different sera.

Early origin and pervasiveness of cellular heterogeneity in some malignant transformations

Nontransformed BALB/3T3 cells were passaged weekly in monolayer culture on plastic dishes and aliquots were regularly assayed for colony production when suspended in agar. During several months of passaging, a single large colony arose once in the agar assay, and its constituent cells were isolated to form a subline of transformed cells. These cells had the fusiform and rounded morphologies characteristic of transformed cells and had a colony-forming efficiency in agar (CFEag) of approximately 10%. Five of the agar colonies were isolated at random and the cell populations of these primary subclones were further analyzed. Four of the five subclonal populations differed from each other in appearance slightly, but consistently, while the fifth had a markedly different colonial morphology. They also differed from one another in CFEag as well as in average diameter of the agar colonies. These general differences among the five subclones remained, although the CFEag and colony sizes changed recognizably in repeated weekly transfers. All of the subclones produced sarcomas in nude mice but did so at different rates. A secondary generation of five subclones was derived from each of three of the original subclonal populations. All the secondary subclones had the same morphology as the primary subclones from which they were derived. The averages of the CFEag and colony sizes of the secondary subclones from each of the subclones differed as a group from the other groups, but they also differed, to a lesser extent, among themselves. Despite the differences noted among the primary subclones in morphology, growth in agar, and tumor production in mice, they were virtually identical in their rapid growth rate on a plastic surface and all shared a high rate of glucose consumption. A second transformed clone arose among the continuously passaged nontransformed cells 5 months after the first one had appeared. Subclones of this clone did not differ recognizably from one another in morphology or in CFEag. The results indicate that recognizable heterogeneity can arise in some tumors during the earliest stages of their development and involve a high proportion of their constituent cells, while it may not become evident in other tumors until much later.

The effect of chronic inflammation on the composition of collagen types in human connective tissue

Biochemical alterations in the connective tissue matrix are a common feature of many diseases, and they account in major part for their functional impairment. Such alterations are especially important in acute and chronic inflammatory diseases where they may take the form of degradation of matrix components or their excessive accumulation leading to fibrosis. Although a wealth of morphologic information is available, very little is known about these changes at the biochemical level. Using human gingival tissue as a model, we have carried out studies aimed at assessing the effects of chronic inflammation on the collagen isotypes comprising the connective tissue matrix. Tissue obtained from patients undergoing surgical treatment for periodontitis was separated on the basis of clinical features into healthy and inflamed portions. After confirming the inflammatory status of each specimen histologically, each set of tissue pairs was extracted at 4 degrees C in 0.5 M acetic acid containing 1 mg/ml of pepsin, and the extracted collagens were fractionated with NaCl. Alpha chains were separated by polyacrylamide slab gel electrophoresis, and methods devised for their quantitation. The results showed that the proportions of type I and III collagens present in normal and inflamed tissues did not differ significantly. In contrast, the type V collagen, which accounted for 0.1 to 1.3% of the total collagens present in normal tissue, was increased by 2- to 9-fold in the chronically inflamed tissue. Because of the unique binding and connecting role type V collagen is thought to play, this alteration may have major pathologic and functional significance.

Attachment and extracellular matrix differences between tendon and synovial fibroblastic cells

Fibroblasts of the synovium of sheathed tendons were isolated, and their biochemical properties were compared with those of the fibroblasts of the remaining tendon. The synovial cells had a lower attachment efficiency than did the tendon cells. On the day of cell isolation the synovial cells synthesized collagen as 10% of their total protein, whereas the tendon cells synthesized 30% collagen. After growth in fetal bovine serum (FBS), the percentage of collagen synthesized by both populations decreased; however, the synovial cells still made less collagen than did the tendon cells (5 versus 11%). On the basis of cyanogen bromide peptide analysis, the synovial cells were found to synthesize Types I and III collagen in primary culture, whereas the tendon cells synthesized only Type I. The synovial cells also synthesized two to three times less sulfated glycosaminoglycans in culture than did the tendon cells. Thus, the two cell populations differed in attachment efficiency and in their biosynthesis of collagen and sulfated glycosaminoglycans. These differences reflect extracellular matrix differences that have been observed in the tendon in vivo. In addition, the results augment existing data showing that not all fibroblasts have identical phenotypes.

Evidence that healthy human gingiva contains functionally heterogeneous fibroblast subpopulations

Six mass cultures of human fibroblasts derived from a single biopsy of a normal gingival papilla tip were studied with regard to their protein, collagen and glycosaminoglycan synthesis in vitro, using incorporation of radiolabelled substances. The proliferation rates, replicative life-spans and cell-size distributions of these mass cultures were determined. There were significant differences among the 6 cultures and these differences persisted throughout numerous cell replications in vitro. It is suggested that functional heterogeneity exists among phenotypically stable fibroblast subpopulations or subpopulation mixtures from normal tissue. The concept of participation of fibroblast subpopulations in disease pathogenesis is supported by these preliminary findings.

The expression of hex A and hex B isozymes of hexosaminidase in parental and experimental human fibroblast cells and their components

The expression of the two major isozyme forms of hexosaminidase (EC 3.2.1.30), hexosaminidase A and hexosaminidase B, has been examined. The parental cells and/or cellular components of parental cells are individually fused using inactivated Sendai virus with the aid of a micromanipulator. The progeny cells produced from such hybrids are subjected to a microenzymatic assay which allows measurements at the single cell level. The lysosomal-deficient cells used in this study are Tay-Sachs and Sandhoff fibroblasts, and the normal cells used are WI-38 (fetal lung fibroblasts), amniotic fluid cells (GM 473), and JASD3 (normal human foreskin). The results show that the ratio of cell components which are fused to form the experimental cell affects the percentage of hexosaminidase A expressed in the progeny cells. Furthermore, our results imply the presence of a "factor" in the Sandhoff cell's cytoplasm which, together with the Tay-Sachs nucleus, is necessary for hexosaminidase A expression in the experimental cell's progeny.

Assay of the beta-glucosidase activity with natural labelled and artificial substrates in cultivated skin fibroblasts from homozygotes and heterozygotes with the Norrbottnian type of Gaucher disease

Fibroblasts from 13 homozygotes and 27 obligate heterozygotes with the Norrbottnian type of Gaucher disease and 17 controls were cultivated and assayed with five beta-glucosidase methods, two with D-[glucose-U-14C] glucosylceramide and three with the artificial substrate 4-methylumbelliferyl-beta-glucoside. Two marker enzymes were assayed on the same cell samples, 4-methylumbelliferyl-beta-galactosidase and N-acetyl-beta-glucosaminidase. The beta-glucosidase activity of cultured fibroblasts, as measured with all five beta-glucosidase methods, was significantly lower (P < 0.001) for Gaucher homozygotes than heterozygotes. There was no overlap between fibroblasts from Gaucher homozygotes and the others with any of the beta-glucosidase methods used. The beta-glucosidase activity was also significantly lower (P < 0.001) for Gaucher heterozygotes than controls. However, none of the five beta-glucosidase assays differentiated between all Gaucher heterozygotes and controls, as several overlaps occurred in each assay.

Microenzymatic assays for lysosomal enzymes in primary amniotic fluid cell cultures

A study of three lysosomal enzymes (hexosaminidase, beta-galactosidase and alpha-galactosidase) in normal primary amniotic fluid cell cultures using a microenzymatic assay is presented. No difference in enzyme activity was found between primary and amniotic cell cultures in passage number one. A progressive change in the proportions of hexosaminidase A and hexosaminidase B with time was demonstrated in culture. The feasibility of this procedure for the early prenatal diagnosis of disorders due to lysosomal enzyme deficiency is discussed.

Inborn errors of lysosomal catabolism--principles of heterozygote detection

Carriers of an inborn error of lysosomal catabolism can be recognized, as they have enzyme levels approximately half those of normal individuals. Of the various tissues readily available for assay, plasma and leukocytes and, in some situations, tears are preferred. Although mixed leukocytes have proved satisfactory in Tay-Sachs screening programs, purified preparations of granulocytes or lymphocytes will allow better discrimination in most situations. Enzymes are assayed relative to some other reference parameter which must be a constant or highly correlated with test enzyme activity. In the two mass screening programs in operation, beta-hexosaminidase A and alpha-mannosidase have both been assayed relative to total beta-hexosaminidase activity. Carrier detection is particularly important in X-linked diseases. The techniques used mostly involve hair roots or fibroblasts and depend on random inactivation of the X chromosome. In the mucolipidoses II and III, in which there are a number of deficient enzymes in cells, carriers may be identified on the basis of the ratio of beta-hexosaminidase I1 and I2 to total hexosaminidase.

Activities of acid hydrolases in fibroblasts from normal and cystinotic children

A study of the lysosomal hydrolases bete-galactosidase, beta-glucuronidase, N-acetyl-beta-D-glucosaminidase, and arylsulphatases A and B has been carried out on fibroblasts cultured from seven patients with cystinosis and eight control subjects. beta-Galactosidase activity was found to be consistently lower in cells derived from cystinotics, while the other enzymes studied showed no significant differences between normals and cystinotics.

Diagnosis of lipogranulomatosis (Farber disease) by use of cultured fibroblasts

The enzyme defect in Farber disease, a deficiency of acid ceramidase, has been demonstrated in cultured skin fibroblasts, which provides a means of confirming the diagnosis during life. The assay can also be performed using cultured amniotic fluid cells and is a potential tool for detection of carriers of the disease.

The mucopolysaccharidoses: inborn errors of glycosaminoglycan catabolism

The mucopolysaccharidoses are genetic disorders of glycosaminoglycan metabolism. Patients with these diseases accumulate within the lysosomes of most tissues excessive amounts of dermatan and/or heparan sulfates, or of keratan sulfate. The clinical consequences of such glycosaminoglycan storage range from skeletal abnormalities to cardiovascular problems, and to motor and mental retardation. In all mucopolysaccharidoses, except Morquio disease, an excessive accumulation of sulfate-labeled glycosaminoglycans has been demonstrated in fibroblasts cultured from the patient's skin. It was subsequently shown that this was due to the deficiency of specific proteins which were named "corrective factors", because their addition to the culture medium effected a normalization of the impaired glycosaminoglycan catabolism in the respective mucopolysaccharidosis fibroblasts. The investigation of the function of the corrective factors, and other studies, led to the identification of the enzymatic defect in each of the mucopolysaccharidoses. Seven lysosomal enzyme deficiencies are now recognized among this group of disorders. A classification of the diseases, according to the mutant gene products, reveals that there is considerable phenotypic variation not only between diseases, but also within several disease types. With the availability of the appropriate enzyme assays, the previous difficulties in diagnosing these disorders have now been overcome. Methods are also available for the prenatal diagnosis, and the detection of heterozygous individuals, in most of the mucopolysaccharidoses. Although correction of the metabolic defect through enzyme replacement has been achieved in tissue culture, many problems remain to be solved before such therapy may become applicable in the patients themselves.

Detection of the carrier state of Hurler's syndrome by assay of alpha-L-iduronidase in leukocytes

The mean specific activity of alph-L-iduronidase in leukocytes from six obligate heterozygotes for Hurler's syndrome was found to be slightly less than one-half of the mean in normal controls; no overlap of normal and known heterozygote values was encountered. The assay has been applied with success to six potential heterozygotes, siblings of a child with Hurler's syndrome. Thus heterozygote detection of Hurler's syndrome is clearly possible; this finding, as well as the ready availability of leukocytes for screening tests, recommends their use for examination of potential carrier status in this disorder.

Lysosomal enzyme levels in human amniotic fluid cells in tissue culture. IV. %A N-acetyl-beta-D-glucosaminidase

Total and % A hexosaminidase were similar for primary cultures and later passages of amniotic fluid cells. The culture variables-through serial passage, within a passage and replicate primary cultures-resulted in some variation in total hexosaminidase, but an insignificant change in % A hexosaminidase. They are unlikely to give rise to any problems in the antenatal diagnosis of Sandhoff's and Tay-Sachs diseases.

Prenatal diagnosis and family studies in a case of propionicacidaemia

In a family with a history of two neonatal deaths, propionicacidaemia was diagnosed retrospectively from stored plasma as the cause of the second death during the mother's next pregnancy. Amniocentesis was performed and a culture of amniotic cells was assayed for propionyl CoA carboxylase activity. The absence of any detectable propionyl CoA carboxylase activity allowed the prenatal diagnosis of propionicacidaemia to be made. Treatment with biotin and a modified aminoacid diet was started in the immediate postnatal period. Investigation of propionyl CoA carboxylase in leucocytes from the parents, siblings and other relations of the patient failed to demonstrate intermediate enzyme activities in even the parents, who were presumably heterozygotes for this condition.

Variability of acid hydrolase activities in cultured skin fibroblasts and amniotic fluid cells

The specific activities of lysosomal hydrolases in cultured skin fibroblasts and amniotic fluid cells showed wide and unpredictable variations between cultures, which may lead to difficulty in differentiating normal, heterozygous, and homozygous cells. However, the variability for a given culture was similar for all enzymes assayed, so that a clearer differentiation of a relative deficiency of a given enzyme could be obtained by expressing its activity in ratio to that of another enzyme. Activity ratios were particularly useful in the evaluation of enzyme levels in cultured amniotic fluid cells. Results of their application to tests of pregnancies at risk for metachromatic leucodystrophy, Krabbe's leucodystrophy, GM1-gangliosidosis, and GM2-gangliosidosis (Sandhoff variant) are presented.