Insulin-deficient diabetes impairs osteoblast and periodontal ligament fibroblast metabolism but does not affect ameloblasts and odontoblasts: response to tetracycline(s) administration

Insulin-deficient, adult, diabetic rats were administrated a tetracycline (either minocycline or a chemically-modified non-antimicrobial tetracycline: CMT) by oral gavage over a 3-week period. Untreated diabetic and non-diabetic rats served as controls. On day 21, all rats received an intravenous injection of 3H-proline, as a radioprecursor of procollagen in bone, dentine and periodontal ligament (PDL) or of amelogenin in enamel; perfusion fixation with an aldehyde mixture was carried out at 20 minutes and 4 hours after isotope injection. The parietal bones (calvaria), mandibules including molars, and lower incisors of these rats were dissected and processed for light microscopic autoradiography to study 3H-proline utilization by osteoblasts, PDL fibroblasts, odontoblasts and ameloblasts. In the control rats, at 20 minutes after 3H-proline injection, silver grains of labeled precursor were detected in the osteoblasts of the periosteal surfaces of the parietal bones. At the 4 hour time period, although some radioprecursor was still present in the osteoblasts, most had progressed to the osteoid matrix. In contrast, the flattened bone-lining cells in the untreated diabetics showed minimal uptake and secretion of labeled proline at both time periods. In both minocycline- and CMT-treated diabetic rats, the labeled proline was localized in the osteoblasts and the osteoid in a pattern reminiscent of that seen in the control rats at both time periods. Of interest, CMT administration appeared to increase the labeling of the osteoid matrix more than minocycline treatment. In non-diabetic control rats, the PDL fibroblasts exhibited a polarized elongated profile and incorporated and secreted radioprecursor similar to that described for the osteoblasts in these animals. The PDL fibroblasts in the untreated diabetics lost their regular arrangement and incorporated little if any 3H-proline; once again, tetracycline administration appeared to normalize, at least in part, the structure and 3H-proline incorporation by these connective tissue cells. In contrast, diabetes and tetracycline administration did not affect the incorporation and secretion of radioprecursor by odontoblasts and secretory ameloblasts during tooth development.

Tetracycline administration normalizes the structure and acid phosphatase activity of osteoclasts in streptozotocin-induced diabetic rats

Diabetes induces osteopenia, which is characterized by a deficiency of osteoid and decreased activity of osteoblasts. We recently found that tetracyclines prevent the loss of osteoid and bone matrix and the degeneration of osteoblasts in diabetic rats by a mechanism independent of their antimicrobial efficacy. However, bone remodeling requires the activity of osteoclasts as well as osteoblasts. To determine the in vivo effects of tetracycline on osteoclasts in long bones, either a tetracycline (minocycline, TC) or its chemically modified non-antibiotic analogue (CMT), 4-de-dimethylaminotetracycline, was administrated daily to streptozotocin-induced diabetic rats by oral intubation. After 21 days, the rats were perfusion-fixed with a mixture of formaldehyde and glutaraldehyde, and the humeri were dissected and processed for ultracytochemical demonstration of acid trimetaphosphatase (ACPase) activity. In untreated non-diabetic (control) rats, the osteoclasts at the zone of provisional ossification exhibited abundant mitochondria and cisterns of rough endoplasmic reticulum (RER) throughout the cytoplasm, prominent stacks of Golgi membranes, and lysosomes in the perinuclear cytoplasm, and numerous various pale vacuoles in the cytoplasmic area adjacent to well-developed ruffled border. Intense ACPase activity was observed in the Golgi saccules, lysosomes, pale vacuoles, and the extracellular canals of ruffled border. The reaction products were also noted along the resorbing bone surfaces associated with the osteoclast ruffled border. The osteoclasts in the untreated diabetic rats showed a cytoplasmic organization similar to that of the non-diabetic control rats, but showed little or no ruffled border which was replaced by a broad clear zone in some of these cells. However, most of the osteoclasts on bone matrix in the diabetics were devoid of both a ruffled border and a clear zone. ACPase activity was detected in the osteoclast cytoplasm of diabetic rat, as in the controls, but to a much lesser extent along the broad clear zone facing the resorbing bone surfaces. The osteoclasts in TC-treated diabetic rats possessed both a clear zone and a small ruffled border. However, in some cases, they lacked both structures reminiscent of the untreated diabetic cells. The osteoclasts of CMT-treated diabetic rats exhibited structural and enzymatic features essentially identical to those of the non-diabetic control rats. These results suggest that the diabetes-induced osteopenia results, at least in part, from degeneration of osteoclasts (as well as atrophic osteoblasts) and that tetracyclines may be effective in preventing these abnormalities by a mechanism not dependent on the drugs' antimicrobial properties.

Tetracycline administration prevents diabetes-induced osteopenia in the rat: initial observations

A tetracycline (doxycycline) was administered daily by oral intubation to adult diabetic rats to assess the effect on skeletal tissue; the rationale--osteopenia is a complication of diabetes and tetracyclines (TCs) were recently found to inhibit pathologic collagen loss (e.g. in diabetic rat skin) by a mechanism independent of their antimicrobial efficacy. Osteopenia was induced by streptozotocin-diabetes as indicated by physical (e.g. specific gravity), chemical (e.g. calcium (Ca) content) and ultrastructural characteristics of the femurs, and TC administration (including treatment with a chemically-modified non-antimicrobial analog) appeared to prevent the development of the bone deficiency disease without affecting the severity of hyperglycemia.

Inhibition of epiphyseal cartilage collagenase by tetracyclines in low phosphate rickets in rats

Drugs in the tetracycline family can inhibit mammalian tissue collagenase both in vitro and in vivo by a mechanism that is independent of antibiotic action. The epiphyseal cartilages of rachitic rats contain extremely high levels of collagenase (CGase), and we have used this model to study further the phenomenon of tetracycline inhibition of tissue CGase. Rickets was induced in rats by phosphate/vitamin D deficiency and parameters of gross bone morphology, bone chemistry, and serum chemistry were evaluated in both rachitic and nonrachitic animals with and without treatment with oral tetracyclines (TETs). Minocycline (or doxycycline) partially suppressed the appearance of many of the expected changes in the rachitic animals, including gross bone hardness, growth plate widening, long bone length, suppression of weight gain, and decreased bone ash content. The effects were dose dependent and were associated with marked suppression of the enhanced CGase activity. Examination of collagen breakdown products by SDS-PAGE documented that the rachitic enzyme behaved like other mammalian collagenases including in vitro inhibition with minocycline 10-20 micrograms/ml and with a nonantibiotic tetracycline. No evidence of TET osseous toxicity was noted, and, in fact, administration of TET to nonrachitic animals had a mildly favorable effect on growth and development. TET suppression of CGase can be demonstrated in a well defined model system and this form of pharmacologic enzyme inhibition can be a useful probe for delineating the role of the enzyme in connective tissue pathology.

A non-antibacterial chemically-modified tetracycline inhibits mammalian collagenase activity

Tetracyclines (including the semi-synthetic analogues, minocycline and doxycycline) are considered useful adjuncts in periodontal therapy because they suppress Gram-negative periodontopathogens. Recently, these antibiotics were found to inhibit mammalian collagenase activity, a property which may also be of therapeutic value. It has been suggested that the anti-collagenase properties of the tetracyclines are independent of their antibiotic efficacy. To advance this hypothesis further, we chemically converted tetracycline hydrochloride to its non-antimicrobial analogue, de-dimethylaminotetracycline. This chemically-modified tetracycline (CMT), although no longer an effective antibiotic, was found to inhibit the in vitro activity of collagenase from partially purified extracts of human rheumatoid synovial tissue and rachitic rat epiphysis. In a preliminary in vivo study, pathologically-excessive collagenase in skin and gingiva was induced by rendering adult male rats diabetic, and the oral administration of CMT to these rats significantly reduced the excessive collagenase activity in both tissues. Moreover, CMT administration did not affect the severe hyperglycemia in these rats but did prevent, at least in part, the diabetes-induced loss of body weight, skin weight, and skin collagen mass; these effects suggest a lack of toxicity in this animal model. A proposed clinical advantage of CMT over conventional tetracyclines, in the treatment of diseases characterized by excessive collagenolytic activity, is the lack of development of antibiotic-resistant micro-organisms during prolonged use. However, the consideration of clinical trials to support this hypothesis must await further laboratory and extensive toxicity tests.

Purification and characterization of a connective-tissue-degrading metalloproteinase from the cytosol of metastatic melanoma cells

A metalloproteinase with activity against type IV collagen, type I collagen and gelatin has been purified from the cytosol of a highly metastatic mouse melanoma by anion-exchange, zinc-chelated and lectin-affinity column chromatography. The purified enzyme has a molecular mass of approx. 59 kDa and on isoelectric focusing in two-dimensional gels produced three spots with apparent isoelectric points (pI) between 5.7 and 6.1. Enzymic activity with collagen, but not gelatin, substrates was latent, requiring activation by trypsin or organomercurials. Trypsin activation of this metalloproteinase was accompanied by a change in molecular mass, whereas autoactivation after 1 month's storage, was not. The degradation of types I and IV collagen by the melanoma enzyme yielded products of lower molecular masses than those yielded by mammalian collagenases, this characteristic thus differentiating this metalloproteinase from classical collagenases.

Enrichment of collagen and gelatin degrading activities in the plasma membranes of human cancer cells

Interactions between connective tissue substrates and proteinases localized to the surface of cancer cells are implicated in cancer invasion. In this report we have compared the enrichment of collagen and gelatin degrading activities and cysteine proteinase(s) in well-characterized (enzyme markers and electron microscopy) subcellular membrane fractions isolated from human small cell lung cancer lines (NCI-H69 and NCI-H82) and the RWP-1 pancreatic cancer line. With each cell line collagenolytic, gelatinolytic, and cysteine proteinase activities were enriched 5- to 128-fold in the plasma membrane fractions with differences noted between microvilli versus smooth membrane profiles. Incubation of tumor plasma membranes with methyl-3H-labeled collagen resulted in extensive degradation of the gamma, beta, alpha 1, and alpha 2 chains, suggesting the combined action of metalloproteinases. Treatment of tumor plasma membranes with the chaotropic agent, 2 M KCl, did not diminish membrane collagen- or gelatin-degrading activity, but extensively leached out the cysteine proteinase, suggesting that the latter enzyme is not an integral membrane protein. Enzyme inhibitors specific for metalloproteinases and cysteine proteinase were used to corroborate enzymatic classification. In conclusion, we have demonstrated variations in the localization of proteinases in the plasma membrane domains of different human cancer cells.

Tetracyclines inhibit human synovial collagenase in vivo and in vitro

To determine if tetracyclines can inhibit human synovial collagenase from rheumatoid tissue, paired synovial tissue (or synovial fluid) was collected from 7 patients before and after oral administration of minocycline (100 mg BID) for 10 days. With each patient serving as his own control, the postminocycline collagenase activities fell an average of 67% from pretreatment values. Qualitative SDS-PAGE revealed decreased loss of alpha collagen components and reduced formation of alpha A digestion fragments. Addition of minocycline or a chemically modified tetracycline to synovial culture media in vitro profoundly inhibited collagenase activity. Further study of this action of tetracyclines could serve as a probe of the role of collagenase in rheumatoid arthritis and lead to development of agents capable of modifying the tissue destructive actions of collagenase.

Systemic tetracycline treatment of alkali-induced corneal ulceration in rabbits

Recent evidence has demonstrated a marked anticollagenolytic effect for the tetracycline antibiotics. We have examined the efficacy of systemic tetracycline hydrochloride in a rabbit model of corneal ulceration. A standard alkali burn (1N sodium hydroxide for 40 s) was delivered to 62 eyes (31 rabbits). Animals were then divided into three groups: group 1 (controls) (ten rabbits [20 eyes]) received no treatment; group 2 (ten rabbits [20 eyes]) received 10 mg/kg/d of tetracycline hydrochloride, given intramuscularly; and group 3 (11 rabbits [22 eyes]) received 50 mg/kg/d. Ulceration occurred in 85% (17/20) of control eyes. The higher dosage of tetracycline was more effective in preventing ulceration than the lower dosage (9.1% vs 55%). Eyes with higher levels of tetracycline in ocular tissues were less likely to ulcerate.

Systemic tetracycline hydrochloride as adjunctive therapy in the treatment of persistent epithelial defects

Recent evidence shows tetracyclines have anticollagenolytic activity that may be clinically effective in disease treatment. This led us to use systemic tetracycline (oral tetracycline hydrochloride 1 g daily divided into 4 doses) as adjunctive therapy in treating 18 patients with persistent corneal epithelial defects. Fourteen of 18 patients healed their defects; within 48 hours (9 patients) and within two weeks (the other 5 responding patients). Two patients showed no effect and two showed disease progression.

Diabetes stimulates procollagen degradation in rat tendon in vitro

To identify the mechanisms responsible for the paucity of recently synthesized collagen in connective tissues during diabetes, in vitro procollagen metabolism was studied in non-diabetic (control) and diabetic rats. Achilles tendons from the two groups were incubated for 1-8 h (35 degrees C) in medium containing [14C]proline and the radiolabeled collagen in the tissue, and that released into the media, were examined by SDS-polyacrylamide gel electrophoresis and fluorography. The bulk of the radiolabeled collagen in tendon from the diabetics was recovered as degradation products; these, but also procollagen and collagen components, were prominent in the control tissues. Moreover, the collagenous components synthesized by the diabetic rat tendons were more readily digested in vitro by trypsin than those produced by control tissues. We conclude that diabetes reduces collagen accretion in connective tissues in part due to increased intracellular degradation of procollagen.

Systemic tetracyclines in the treatment of noninfected corneal ulcers: a case report and proposed new mechanism of action

Corneal melting refers to a condition in patients whose corneas undergo progressive necrosis of stromal tissue despite being culture negative. Recent evidence has shown that systemic tetracyclines demonstrate anti-collagenolytic activity that may have clinical effectiveness in disease treatment. The evidence led us to try this modality as adjunct therapy in the treatment of an 80-year-old white man with a noninfected corneal ulcer. One gram of tetracycline in four divided doses led to a dramatic resolution of the corneal ulcer. This positive result supports the new concept that tetracycline therapy inhibits tissue collagenolytic enzyme activity by a mechanism unrelated to its antibacterial efficacy and may prove useful in the treatment of nonspecific corneal ulceration.

Tetracyclines inhibit tissue collagenases. Effects of ingested low-dose and local delivery systems

In a series of experiments, Golub et al. demonstrated that tetracyclines, but not other antibiotics, can inhibit mammalian collagenases and proposed that this property could be useful in treating diseases, such as periodontal disease (but also included certain medical conditions, e.g., corneal ulcers) characterized by excessive collagen degradation (J Periodont Res 1983, 1984 and 1985; Experientia 1984; Cornea 1984). One effect was the dramatic reduction of tissue collagenase activity within the gingival crevicular fluid (GCF) of periodontal pockets after administering a standard regimen of a tetracycline (e.g., 200 mg minocycline or 1000 mg tetracycline/day). The preliminary studies described below determined the effect of (1) low-dose (LD; 40-80 mg/day) orally administered minocycline on GCF collagenase activity and on the subgingival microflora (Exp. I), and (2) tetracycline-loaded monolithic fibers (TF) on collagenase activity in vitro (Exp. II). In Exp. I, GCF collagenase activity was reduced by 45 to 80% 2 weeks after initiating LD minocycline therapy, an effect that lasted for at least several weeks after stopping drug treatment. No consistent change in the relative proportions of G(+), G(-) and motile subgingival microorganisms was detected as a result of LD treatment suggesting that the reduction in GCF collagenase activity was a direct inhibition of the enzyme by the drug. In Exp. II, 3- and 6-mm lengths of TF in vitro established tetracycline concentrations in 250 microliters of 132 micrograms/ml, from 3-mm lengths, and 265 micrograms/ml, from 6-mm lengths, after an 18-hour incubation.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo assay of crevicular leukocyte migration. Its development and potential applications

Defects in neutrophil or polymorphonuclear leukocyte (PMNL) chemotaxis have been observed in a number of clinical conditions, including Down's syndrome and insulin-dependent diabetes mellitus (IDDM), which tend to be associated with severe forms of periodontal disease. In addition, impaired PMNL chemotaxis is frequently detected in individuals with localized juvenile periodontitis (LJP). The ability to monitor PMNL function in vivo at the gingival sulcus should therefore be useful as a diagnostic test. In this regard, we developed a technique which measures the response of PMNLs to a chemotactic agent, e.g., casein and N-formylmethionylleucylphenylalanine (N-FMLP) placed directly into gingival crevices. The development of the technique and its relationship to in vitro assays of chemotaxis are discussed, and data obtained from tests of the assay on control and streptozotocin-induced diabetic rats and human subjects with various periodontal diseases and IDDM are presented. As compared with healthy subjects and control animals, atypical (double peak) and reduced crevicular PMNL response patterns were observed during oral and systemic diseases. This suggests that the in vivo assay with appropriate modifications can be used diagnostically to assess PMNL migratory dysfunction and to identify individuals who may be susceptible to severe forms of periodontal disease.

Double-blind, randomized trial of a calf lung surfactant extract administered at birth to very premature infants for prevention of respiratory distress syndrome

Organic solvent extraction of surfactant obtained by lavage of calf lungs yields a highly surface-active material. A double blind, randomized clinical trial to determine the effect of this material on respiratory distress syndrome in premature infants was initiated in the Neonatal Intensive Care Unit at the University of Rochester in December 1983. Infants 25 to 29 weeks gestational age were eligible for entry into the trial. At the time of this interim analysis 32 patients had been randomly selected and entered into the trial, 16 surfactant-treated patients and 16 in a control group who received only saline. At birth, intrapulmonary instillation of the calf lung surfactant extract dispersed in saline or saline alone occurred in the delivery room immediately after intubation and prior to ventilation; infants were then ventilated and treated as usual. At 6, 12, 24, 48, and 72 hours after birth, the severity of respiratory distress was categorized as either minimal, intermediate, or severe based on oxygen and mean airway pressure requirements. Differences observed at six hours after birth were of marginal significance, but at 12 and 24 hours the surfactant-treated group had significantly (P less than .01) less severe respiratory distress compared with the control group. Differences between treated and control infants were not statistically significant at 48 and 72 hours after birth. In four surfactant-treated infants the severity of respiratory distress worsened between 24 and 48 hours after birth, suggesting that one dose of surfactant at birth may not be sufficient for some infants.

Diversity of melanoma plasma membrane proteinases: inhibition of collagenolytic and cytolytic activities by minocycline

The tissue-destructive proteinases of B16-BL6 melanoma cells from C57BL/6 mice and subcellular fractions were examined. Cancer cell organelles were isolated following nitrogen cavitation with the use of sucrose density gradient centrifugation. Serine, cysteine, and metalloproteinases were assayed with the use of radiolabeled proteins and synthetic substrates. Tumor-induced red blood cell lysis was quantitated by measurement of the release of isotope from 59Fe-labeled red blood cells (RBC) cocultivated with melanoma cells; the RBC were from Wistar rats. Enzyme inhibitors with specificity toward different classes of proteinases were used in the above assays to categorize the enzymes responsible for substrate degradation. Results indicated that intact melanoma cells, cell organelles, and cytosol contain proteinases that can degrade collagen and gelatin and lyse normal RBC. Melanoma plasma membranes are highly enriched in collagenase, gelatinase, cysteine proteinase, plasminogen activator, and cytolytic activity. The inhibition of tumor collagenolytic, gelatinolytic, and cytolytic activities by EDTA and 1,10-phenanthroline but not by diisopropyl fluorophosphate and N alpha-p-tosyl-L-lysine chloromethyl ketone indicates that metalloproteinases are the active enzymes in these assays. Minocycline, a synthetic tetracycline with demonstrable inhibitory activity with other mammalian collagenases, also inhibited melanoma collagenolytic and cytolytic activities.

The application of a collagen stabilizer to the gingiva of the beagle dog. Effect on ligature-induced periodontal disease

The objective of this study was to determine the effect of crevicular application of a collagen stabilizer on ligature-induced periodontal disease in beagle dogs. Fourteen male and female dogs, 15 months of age, were studied. The mandibular first molars and third and fourth premolars were ligated for 6 months and moderate periodontitis resulted. Ligatures were removed for 2 months and then replaced for an additional 3 months to experimentally mimic the episodic changes seen in human periodontal disease. Following this phase, ligatures were removed and the animals were assigned to a placebo or treatment group. Medications were then applied intracrevicularly, three times a week over 5 months using an IMAX irrigator. Clinical indices measured were plaque index (PI), gingival index (GI), gingival crevicular fluid flow (GCF), attachment level (AL), pocket depth (PD) and standardized radiographic analysis of alveolar bone height. While overall changes in PI, GI and GCF were not significant, the results showed that alveolar bone regeneration was increased approximately twice as much in the treatment group as compared to the placebo group, PD improved by 20% vs. 12.5% (P less than 0.001) and AL improved by 8.8% vs. 4.5% (P less than 0.001). The data were also evaluated in terms of the response in more severe sites as compared to those less severe. The results of these evaluations showed the more severe sites to be significantly more responsive to treatment than the less severe sites.(ABSTRACT TRUNCATED AT 250 WORDS)

The effect of alloxan diabetes on prolyl and lysyl hydroxylase activity in uninflamed and inflamed rat gingiva

The influence of diabetes on gingival inflammation was studied through its effect on prolyl and lysyl-hydroxylase activities and on tissue-collagen content. Inflammation induced for 7 days with either endotoxin or antigen-antibody complexes reduced the activity of both enzymes by about 45 per cent, and decreased the concentration of soluble and insoluble collagens. Diabetes alone decreased the enzyme activity by more than 50 per cent but prevented the loss of the soluble and insoluble collagens which occurs during inflammation. The complex interaction of diabetes and inflammation on collagen metabolism in gingival tissue may be explained in part by abnormalities of collagen synthesis; alterations in collagen maturation and degradation, and in leukocyte function, may also occur.

Tetracyclines inhibit parathyroid hormone-induced bone resorption in organ culture

Several tetracyclines (minocycline, doxycycline, tetracycline), in levels approximating physiologic concentrations, were found to inhibit parathyroid hormone-induced bone resorption in organ culture; the specificity of this effect was demonstrated by comparison with other (non-tetracycline) types of antibiotics. The ability of tetracyclines to inhibit bone resorption is consistent with the recent proposal by Golub et al. that these antibiotics can inhibit mammalian collagenolytic enzymes by a mechanism unrelated to the drug's antibacterial efficacy, a property which could be therapeutically useful in diseases characterized by excessive collagen breakdown.

A comparison of 3 systems for quantifying gingival crevicular fluid with respect to linearity and the effects of qualitative differences in fluids

This investigation compares the Periotron 6000, Periotron 600, and ninhydrin area systems for quantifying gingival fluid. All systems have highly significant (p less than 0.001) linear relationships between measurements and fluid volumes. Additional curvilinear components have virtually no clinically significant implications. Qualitative differences in fluid only have clinically significant implications for the Periotron 600. When both quantitative and qualitative properties of gingival crevicular fluid are being investigated, the Periotron 6000 is the system of choice.