Hyaluronic acid and hyaluronidase activity in gingival exudate from sites of acute ulcerative gingivitis in man

Drug Release and Cytotoxicity of Hyaluronic Acid and Zinc Oxide Gels, An In-Vitro Study

Hyaluronic acid (HA) is a naturally occurring biopolymer, with a remarkable wound healing property. Zinc-oxide non-eugenol is a material widely used for periodontal dressing in dentistry. However, it has been reported that zinc oxide non-eugenol is toxic to osteoblasts and fibroblasts. Hence, the present study aimed to evaluate the drug release and cytotoxicity of HA and zinc-oxide gels. Hydrogels of HA and zinc oxide were formulated with carbopol as a carrier. In vitro drug release was performed by UV spectrophotometry, dialysis, and vial bag methods. Cytotoxicity assessment of HA and zinc-oxide gels was performed in human periodontal ligament fibroblasts (HPdLF) and human gingival fibroblasts (hGFs). An inverted phase-contrast microscope was used to assess the morphological changes. At 24 and 48 hr, HPdLF cells showed the highest viability in 0.1% low molecular weight-HA (LMW-HA) with a median value of 131.9, and hGFs showed the highest viability in 5% LMW-HA with a median of 129.56. The highest viability of HPdLF cells was observed in 5% high molecular weight-HA (HMW-HA), with a median value of 127.11. hGFs showed the highest viability in 1% HMW-HA with a median value of 97.99. Within the limitations of the present study, we concluded that LMW-HA is more efficient than HMW-HA. Both HPdLF and hGF cells showed complete cell morbidity with zinc-oxide hydrogels. Therefore, zinc oxide-based gels in concentrations as low as 9% could be toxic intraorally to soft tissues that harbor gingival and periodontal ligament fibroblasts.

Updates and Original Case Studies Focused on the NMR-Linked Metabolomics Analysis of Human Oral Fluids Part I: Emerging Platforms and Perspectives

1H NMR-based metabolomics analysis of human saliva, other oral fluids, and/or tissue biopsies serves as a valuable technique for the exploration of metabolic processes, and when associated with ’state-of-the-art’ multivariate (MV) statistical analysis strategies, provides a powerful means of examining the identification of characteristic metabolite patterns, which may serve to differentiate between patients with oral health conditions (e.g., periodontitis, dental caries, and oral cancers) and age-matched heathy controls. This approach may also be employed to explore such discriminatory signatures in the salivary 1H NMR profiles of patients with systemic diseases, and to date, these have included diabetes, Sjörgen’s syndrome, cancers, neurological conditions such as Alzheimer’s disease, and viral infections. However, such investigations are complicated in view of quite a large number of serious inconsistencies between the different studies performed by independent research groups globally; these include differing protocols and routes for saliva sample collection (e.g., stimulated versus unstimulated samples), their timings (particularly the oral activity abstention period involved, which may range from one to 12 h or more), and methods for sample transport, storage, and preparation for NMR analysis, not to mention a very wide variety of demographic variables that may influence salivary metabolite concentrations, notably the age, gender, ethnic origin, salivary flow-rate, lifestyles, diets, and smoking status of participant donors, together with their exposure to any other possible convoluting environmental factors. In view of the explosive increase in reported salivary metabolomics investigations, in this update, we critically review a wide range of critical considerations for the successful performance of such experiments. These include the nature, composite sources, and biomolecular status of human saliva samples; the merits of these samples as media for the screening of disease biomarkers, notably their facile, unsupervised collection; and the different classes of such metabolomics investigations possible. Also encompassed is an account of the history of NMR-based salivary metabolomics; our recommended regimens for the collection, transport, and storage of saliva samples, along with their preparation for NMR analysis; frequently employed pulse sequences for the NMR analysis of these samples; the supreme resonance assignment benefits offered by homo- and heteronuclear two-dimensional NMR techniques; deliberations regarding salivary biomolecule quantification approaches employed for such studies, including the preprocessing and bucketing of multianalyte salivary NMR spectra, and the normalization, transformation, and scaling of datasets therefrom; salivary phenotype analysis, featuring the segregation of a range of different metabolites into ‘pools’ grouped according to their potential physiological sources; and lastly, future prospects afforded by the applications of LF benchtop NMR spectrometers for direct evaluations of the oral or systemic health status of patients at clinical ‘point-of-contact’ sites, e.g., dental surgeries. This commentary is then concluded with appropriate recommendations for the conduct of future salivary metabolomics studies. Also included are two original case studies featuring investigations of (1) the 1H NMR resonance line-widths of selected biomolecules and their possible dependence on biomacromolecular binding equilibria, and (2) the combined univariate (UV) and MV analysis of saliva specimens collected from a large group of healthy control participants in order to potentially delineate the possible origins of biomolecules therein, particularly host- versus oral microbiome-derived sources. In a follow-up publication, Part II of this series, we conduct censorious reviews of reported observations acquired from a diversity of salivary metabolomics investigations performed to evaluate both localized oral and non-oral diseases. Perplexing problems encountered with these again include those arising from sample collection and preparation protocols, along with 1H NMR spectral misassignments.

Hyaluronan (hyaluronic acid) in human saliva

Hyaluronan (hyaluronic acid) is a glycosaminoglycan that functions as a constituent of ground substance, a mediator of cell proliferation and would healing, and that plays a prominent part in tumorigenesis as well as in embryogenesis. Its presence and possible role in saliva has been subjected to little study. Unstimulated and stimulated pure parotid and mixed saliva was obtained from 10 volunteers. The protein content of the samples was assayed and the hyaluronan concentration was evaluated by means of an enzyme immunosorbent-like assay using a hyaluronan-binding peptide. Stimulated whole saliva had the highest protein content (mean 1.26 mg/ml) followed by unstimulated parotid saliva (1.15 mg/ml), stimulated parotid saliva (0.95 mg/ml) and unstimulated whole saliva (0.93 mg/ml). Absolute hyaluronan concentrations were highest in unstimulated whole saliva (mean 459.2 ng (nanograms)/ml), and lowest in stimulated parotid saliva (82.7 ng/ml). When hyaluronan concentrations are expressed as ng/mg of protein, the highest are in the unstimulated whole saliva (mean 477.5 ng/mg protein) followed by stimulated parotid saliva (229.7 ng/mg), unstimulated parotid saliva (179.6 ng/mg) and stimulated whole saliva (159.9 ng/mg). There are wide variations in the levels of hyaluronan in human saliva depending on the type of saliva and the conditions at the time of collection. Regulation of hyaluronan metabolism represents an intricate balance between production and degradation, and it is unclear whether elevated concentrations of hyaluronan in response to tissue proliferation, regeneration or repair. The hyaluronan may contribute to the healing properties of saliva, assisting in protecting the oral mucosa and adding to the lubricating properties of saliva.

Hyaluronan, a possible ligand mediating Treponema denticola binding to periodontal tissue

Binding of Treponema denticola ATCC 35405 to glycosaminoglycans, fibrinogen, type I collagen and porcine periodontal ligament epithelial cells was studied using an enzyme-linked immunosorbent assay. T. denticola bound to hyaluronan (hyaluronic acid) and its hexameric fragments. whereas little or no binding was detected to chondroitin-4-sulfate or dermatan sulfate proteoglycan. Binding of T. denticola to hyaluronan gradually increased during the 2-h incubation time. In contrast, binding to fibrinogen and type I collagen was more rapid, peaking within 5 min. T. denticola also bound to microbeads coated with hyaluronan and formed visible aggregates in solution. Pretreatment of the bacteria with hyaluronan or fibrinogen inhibited binding to hyaluronan. Gelatin, bovine serum albumin, chondroitin-4-sulfate, chondroitin-6-sulfate, heparin, dermatan sulfate, glucuronic acid, N-acetylglucosamine and N-acetyl-galactosamine did not inhibit binding. Binding was also inhibited by heating T. denticola and by pretreatment of the spirochetes with sodium periodate, phenylmethylsulfonyl fluoride, and p-chloromercurybenzoic acid. All these treatments also inhibited the chymotrypsin-like activity of T. denticola. Hyaluronan strongly inhibited binding of T. denticola to epithelial cells, whereas the other glycosaminoglycans and N-acetyl-glucosamine did not. The results show that T. denticola binds to hyaluronan, possibly by a mechanism involving the chymotrypsin-like surface protein of T. denticola.

Gingival crevicular fluid glycosaminoglycan levels in patients with chronic adult periodontitis

This study investigated levels of hyaluronan and chondroitin-4-sulphate in the crevicular fluid of patients with chronic adult periodontitis at diseased and healthy sites before and after treatment. The relationship between clinical diagnostic parameters and levels of glycosaminoglycans in gingival crevicular fluid were also analysed. Within each patient, 4 sites either mesial or distal and on single rooted teeth were classified as diseased or healthy using a modified gingival index, pocket depth and attachment loss. Crevicular fluid was collected from each site using glass micropipettes and analyzed for glycosaminoglycan content by cellulose acetate electrophoresis. Significantly higher levels of chondroitin-4-sulphate were detected at diseased sites prior to treatment correlating with increased pocket depth or attachment levels. Following a period of treatment consisting of oral hygiene instruction and root planing, the patients were reassessed for their response to treatment by measuring the modified gingival index, pocket depth, attachment loss and levels of glycosaminoglycans. Analysis of glycosaminoglycan levels at diseased sites that demonstrated a poor response to treatment also demonstrated significantly higher levels of chondroitin-4-sulphate than those sites that responded well to treatment. Hyaluronan levels were less significantly associated with clinically succesful treatment. This study confirmed the use of the sulphated glycosaminoglycan chondroitin-4-sulphate as a potential diagnostic aid of periodontal tissue destruction; however, further longitudinal studies are required to assess their performance.

Host enzymes in gingival crevicular fluid as diagnostic indicators of periodontitis

Host responses to periodontal infections include the production of several families of enzymes that are released by stromal, epithelial or inflammatory cells. Study of these enzymes in gingival crevicular fluid may lead to insights into pathogenesis and may provide a rational basis for the development of novel diagnostic tests. However, analogous to other diagnostic interventions in dentistry and medicine, validation of host enzymes as diagnostic indicators is dependent on clear-cut demonstrations of the identity of the enzyme, reproducibility, diagnostic accuracy and clinical utility. The enzyme of interest should be readily measured over a broad range of disease severity and in varied clinical settings. Ideally, the enzyme should also be an essential component of proposed pathogenic mechanisms. In this context, the connective tissue matrix degrading enzymes elastase, collagenase and gelatinase are promising because of their apparently central role in periodontal attachment loss and disease progression. Sensitive and specific assays are also available to quantify these enzymes. Other work on enzymes associated with cell death (aspartate aminotransferase, lactate dehydrogenase) and several neutrophil lysosomal enzymes (beta glucuronidase, arylsulphatase, cathepsins) has demonstrated positive associations between enzyme levels and attachment loss and inflammation. While numerous cross-sectional studies have indicated that the levels of hydrolytic enzymes in gingival crevicular fluid parallel the severity of periodontal lesions, there are much less data on reproducibility, diagnostic accuracy and clinical utility in longitudinal studies. As appropriate study design is an essential prerequisite for establishing the efficacy of host enzymes as diagnostic tests, future clinical investigations should include: (1) individuals who would most likely benefit by early diagnosis, i.e., rapidly progressive and recurrent periodontitis cases; (2) longitudinal, cohort study designs to show that attachment loss is temporally linked with large increases in enzyme activity; (3) the use of a battery of tests to overcome intrinsic problems of low predictive values when prevalence of active disease is low. In the final analysis, the utility of host enzymes as diagnostic indicators will need to be examined in randomized controlled trials in which the question is asked: are patients better off as a result of testing?

The effects of orthodontic tooth movement on the glycosaminoglycan components of gingival crevicular fluid

In this study, gingival crevicular fluid (GCF) was collected from around a canine tooth, in children, before and during orthodontic tooth movement. The aim was to identify and quantify the glycosaminoglycan (GAG) components of GCF and relate them to tooth movement, gingival inflammation, plaque accumulation, pocket probing depth and GCF volume recorded at the site of sampling. GAG in GCF samples, collected for a 15-min period into microcapillary tubes, were separated electrophoretically, stained with Alcian blue and quantified using a laser densitometer. 2 GAG components of hyaluronic acid (HA) and chondroitin sulphate (CS) were identified. The increase in GCF volume during orthodontic tooth movement was only partly due to increased gingival inflammation. GAG levels varied with different types of orthodontic tooth movement. In GCF, levels of CS, in particular, may reflect the changes in the deeper periodontal tissues which could be monitored during orthodontic tooth movements.

Glycosaminoglycans and periodontal disease: analysis of GCF by safranin O

The purpose of this study was to quantify glycosaminoglycans (GAG) released into the gingival crevicular fluid (GCF) during health, gingivitis, and adult periodontitis. The investigation tested the hypothesis that increased amounts of GAG can be measured in GCF associated with gingivitis and adult periodontitis as compared to health. An individual patient's sampling sites were assigned to either a health (control) group or 1 of 3 experimental groups, gingivitis, periodontal "maintenance" (perio-M), or periodontal "non-maintenance" (perio-NM) according to standard clinical criteria of pocket probing depth, bleeding on probing, and radiographic evidence of bone loss. The perio-M group was defined as a periodontal patient who had received a dental prophylaxis and/or root planning within 6 months prior to GCF collection. The perio-NM group had received no periodontal therapy during the previous 6 months. Subsequent to air-drying and isolation, GCF was collected by a microcapillary pipette held at the gingival margin. All fluid samples were digested overnight at 37 degrees C with 25 micrograms of papain and analyzed for GAG content using a chondroitin-4-sulfate standard. Data generated from safranin "O" dye binding assays of GAG revealed 4.41 +/- 9.82 ng GAG from the health (control) group (n = 23); the gingivitis group (n = 13) showed 15.23 +/- 11.85 ng GAG/sample; perio-M group (n = 11) showed 23.64 +/- 12.98 ng GAG/sample and the perio-NM group (n = 12) exhibited 119.08 +/- 33.14 ng GAG/sample.(ABSTRACT TRUNCATED AT 250 WORDS)