Antioxidant response of osteoblasts to doxycycline in an inflammatory model induced by C-reactive protein and interleukin-6.

OBJECTIVES: Investigation of osteoblastic responses to oxidative stress, induced by C-reactive protein (CRP) and IL-6 and ameliorating effects of doxycycline (Dox); using assays for 5-alpha dihydrotestosterone (DHT) as an antioxidant marker of healing. IL-6 and CRP are risk markers of periodontitis and prevalent comorbidities in periodontitis subjects. METHODS: Confluent monolayer cultures of osteoblasts were incubated with radiolabelled testosterone (14C-T) as substrate, in the presence or absence (Control) of pre-determined optimal concentrations of CRP, IL-6, Dox; alone and in combination (n=8) for 24h in MEM. The eluent was solvent-extracted for steroid metabolites. They were separated using TLC in a benzene/ acetone solvent system 4:1 v/v; and quantified using radioisotope scanning. The identity of formed metabolites was confirmed using the mobility of cold standards added to the samples and disclosed in iodine. Further confirmation of the authenticity of DHT was carried out by combined gas chromatrography-mass spectrometry, after derivatization to pentafluorobenzyloxime trimethyl silyl ether. RESULTS: The yields of DHT from 14C-testosterone showed 2-fold and 1.8-fold- inhibition in response to IL-6 and CRP respectively and 28% stimulation in response to Dox, via the 5-alpha reductase pathway. The combination of IL-6 + CRP showed a 2-fold reduction in the yields of DHT, elevated to control values when combined with Dox (n=8; p<0.001). Yields of 4-androstenedione showed an inverse relationship to those of DHT, in response to the agents tested, in keeping with the 17-beta hydroxysteroid dehydrogenase pathway. CONCLUSIONS: Inhibition of DHT synthesis in osteoblasts by IL-6 and CRP was overcome by doxycycline. Oxidative actions of IL-6 and CRP; and antioxidant actions of Dox are reinforced by the metabolic yields of DHT in response to agents tested. Using a novel metabolically active model allows closer extrapolation to in vivo conditions; in the context of adjunctive therapeutic applications for periodontitis and prevalent comorbidities.

Anti-inflammatory Actions of Adjunctive Tetracyclines and Other Agents in Periodontitis and Associated Comorbidities.

The non-antimicrobial properties of tetracyclines such as anti-inflammatory, proanabolic and anti-catabolic actions make them effective pharmaceuticals for the adjunctive management of chronic inflammatory diseases. An over-exuberant inflammatory response to an antigenic trigger in periodontitis and other chronic inflammatory diseases could contribute to an autoimmune element in disease progression. Their adjunctive use in managing periodontitis could have beneficial effects in curbing excessive inflammatory loading from commonly associated comorbidities such as CHD, DM and arthritis. Actions of tetracyclines and their derivatives include interactions with MMPs, tissue inhibitors of MMPs, growth factors and cytokines. They affect the sequence of inflammation with implications on immunomodulation, cell proliferation and angiogenesis; these actions enhance their scope, in treating a range of disease entities. Non-antimicrobial chemically modified tetracyclines (CMTs) sustain their diverse actions in organ systems which include anti-inflammatory, anti-apoptotic, anti-proteolytic actions, inhibition of angiogenesis and tumor metastasis. A spectrum of biological actions in dermatitis, periodontitis, atherosclerosis, diabetes, arthritis, inflammatory bowel disease, malignancy and prevention of bone resorption is particularly relevant to minocycline. Experimental models of ischemia indicate their specific beneficial effects. Parallel molecules with similar functions, improved Zn binding and solubility have been developed for reducing excessive MMP activity. Curbing excessive MMP activity is particularly relevant to periodontitis, and comorbidities addressed here, where specificity is paramount. Unique actions of tetracyclines in a milieu of excessive inflammatory stimuli make them effective therapeutic adjuncts in the management of chronic inflammatory disorders. These beneficial actions of tetracyclines are relevant to the adjunctive management of periodontitis subjects presenting with commonly prevalent comorbidities addressed here.

Oxidative actions of hydrogen peroxide in human gingival and oral periosteal fibroblasts: responses to glutathione and nicotine, relevant to healing in a redox environment.

BACKGROUND: This study aims to validate pro-oxidant actions of nicotine (N), using hydrogen peroxide (H2O2) and the antioxidant glutathione (G) in an in vitro model of human gingival fibroblasts (HGF) and human oral periosteal fibroblasts (HPF); radiolabelled androgens are used as biomarkers of redox status. Oxidative stress is an important mediator of inflammatory repair. The androgen metabolite 5α-dihydrotestosterone (DHT) is an effective biomarker of oxidative stress and healing. METHODS: 6 Cell-lines of HGF and HPF established in confluent monolayer culture were incubated in Eagle's MEM using 14C-testosterone and 14C-4-androstendione as substrate; in conjunction with effective concentrations of N, G and H2O2 established at N250, G3 µg/ml and 3%H2O2 w/w, 0.5 µl/ml. Combinations of H2O2G and H2O2GN were used in order to compare the oxidative effects of N/H2O2 and their responses to glutathione. At 24 h, the medium was solvent extracted, evaporated to dryness and subjected to TLC in a benzene/acetone solvent system 4:1 v/v for the separation of metabolites. The separated metabolites were quantified using a radioisotope scanner. RESULTS: The mean trends of 6 cell-lines for both substrates and each cell type demonstrated that the yield of the main metabolite DHT was significantly reduced by N and H2O2 alone (2-fold, n=6; p<0.01). The inhibition caused by H2O2 was overcome by the antioxidant glutathione in the combination H2O2G, to values similar to those of controls (n=6; p<0.01). It is relevant that when N was added to this neutralized combination, the decrease in yields of DHT triggered by N were comparable to those induced by H2O2; and retaining the positive effect of G. CONCLUSION: Oxidative stress mediated by H2O2 was overcome by glutathione and recurred when nicotine was added, suggestive of a pro- oxidant role for nicotine. Androgen biomarkers are a sensitive index of oxidative stress which affects wound healing.

Associations between periodontitis and systemic inflammatory diseases: response to treatment.

There is a significant prevalence of subjects with periodontitis presenting with other inflammatory conditions such as coronary heart disease, insulin resistance and arthritis. This pattern of disease presentation underscores the importance of inflammatory loading from chronic diseases, in driving their pathogeneses in a multidirectional manner. Pro-inflammatory cytokines and other agents play an important role in this process; for example, a single nucleotide polymorphism of the TNF-α gene is associated with significant periodontal attachment loss in patients with coronary heart disease. Changes in gene expression associated with inflammation and lipid metabolism in response to oral infection with the periodontal pathogen Porphyromonas gingivalis (Pg) have been demonstrated in mouse models, independent of the demonstration of atherosclerotic lesions. Insulin resistance is considered to be a chronic low-grade inflammatory condition, associated with altered glucose tolerance, hypertriglyceridemia, central obesity and coronary heart disease. It is accompanied by elevated levels of IL-1, IL-6 and TNF-α also relevant to the progression of periodontitis. There is evidence that uncontrolled periodontal disease contributes to maintenance of systemic diseases, including rheumatoid arthritis (RA), with increased risk of periodontitis in subjects with RA. The periodontal pathogen Pg is significant in contributing to citrullination of proteins resulting in immune dysregulation and autoimmune responses, seen in RA. However, they are both multifactorial chronic diseases with complex etiopathogeneses that affect their presentation. Consistent but weak associations are seen for surrogate markers of periodontitis such as tooth loss, with multiple systemic conditions. Effective treatment of periodontitis would be important in reducing systemic inflammatory loading from chronic local inflammation and in achieving systemic health. Lack of a consistent cause and effect relationship in all subjects would be influenced by genetic, epigenetic and other subject variables, although there are clear mechanisms that link the associations. This article includes an appraisal of patents and their applications.

Nutritional antioxidants and their applications in cardiometabolic diseases.

There is an increasing global trend in cardiometabolic disorders being a leading cause of morbidity and mortality. Adverse dietary habits and sedentary lifestyles contribute to cardiovascular disease (CVD) and diabetes mellitus (DM). Dietary nutrients in nuts have attracted attention in recent literature due to their beneficial effects on CVD by attenuating lipid profiles, inflammation and oxidative stress. There is well-established evidence of the pharmacological properties of micronutrients that render them therapeutically effective in chronic inflammatory diseases. Although caution should be exercised in using antioxidant supplementation, antioxidant foods as dietary components play an important role in the management of cardiometabolic disorders. There is documented evidence of disease-modifying effects of nutritional compounds with anti-inflammatory and antioxidant effects. They have specific applications in ameliorating oxidative stress- induced inflammatory diseases such as DM and CVD. It is relevant that dietary components that influence risk of DM, have similar effects on inflammatory biomarkers of cardiovascular risk. Polyphenolic compounds such as flavonoids, isoflavones, phenolic acids and lignan contribute to increased plasma antioxidant capacity, decreased oxidative stress markers and reduced total and LDL cholesterol. They modulate genes associated with metabolism, stress defence, detoxification and transporter proteins. Their antioxidant and anti-inflammatory actions have specific applications for pathologies associated with chronic low-grade systemic inflammation that underpins progression of DM and CVD. Mechanisms involved depend on the structure of the compound, redox status of the inflammatory milieu and other interactions. Bioactive phytochemicals play an important therapeutic role in attenuating oxidative damage induced by metabolic syndrome associated with atherogenic dyslipidaemia and a pro-inflammatory, pro-thrombotic state, at a sub-cellular level. It would be critical to formulate optimal proportions and their combinations for therapeutic efficacy, based on synergistic interactions. Some of these mechanisms and potential actions are discussed.

Mechanisms for redox actions of nicotine and glutathione in cell culture, relevant to periodontitis.

The oxidative effect of nicotine was investigated using androgen biomarkers of redox status and wound healing in fibroblasts; using the antioxidant glutathione for confirmation of responses. Cultures of human gingival (HGF) and periosteal fibroblasts (HPF) were incubated with substrates 14C-testosterone/14C-4-androstenedione in the presence or absence of serial concentrations of nicotine (N(100-500)), glutathione (G(1-5)) and their combinations, in medium. At 24 h the medium was solvent extracted for metabolites, separated by TLC and quantified using radioisotope scanning. Nicotine caused significant inhibition in yields of the physiologically active metabolite 5α-dihydrotestosterone (DHT) in HGF and HPF, overcome to varying degrees by the anti-oxidant glutathione (n = 6; p<0.01, one way ANOVA); this is suggestive of moderation of an oxidative mechanism induced by nicotine. Down-regulation of 5α-reductase activity by nicotine resulting in reduced yields of DHT was overcome by glutathione. Overcoming oxidative stress in a redox environment is applicable to treatment outcome.

Inflammatory mechanisms and redox status in periodontal and cardiometabolic diseases: effects of adjunctive nutritional antioxidants and statins.

Periodontal pathogens in plaque biofilm initiate periodontitis, which is influenced by genetic and environmental factors. The resultant pro-oxidant status imposed on the periodontium, exacerbated by episodic hyperinflammatory damage contributes to progression of periodontitis and tooth loss in susceptible subjects. Increasing documentation of bi-directional connections between periodontal and cardiometabolic disorders makes it an intriguing area of therapeutic intervention for mutual benefit. Periodontitis and associated comorbidities demonstrate similar risk markers of inflammation during disease progression. Depending on the extent and severity of the inflammatory response, periodontitis could impact significantly on systemic inflammatory loading and influence the progression of endothelial dysfunction, atherosclerotic plaque instability, dyslipidaemia and insulin resistance. Some of the common mechanisms involved are discussed, relevant to periodontal and cardiometabolic disorders which have been documented as having a bidirectional relationship with periodontal disease progression; abating in response to treatment. Periodontal disease may be a useful marker of a susceptible immune system, or directly affect the progression of systemic diseases due to inflammatory loading. These mechanisms mediated by coordinated actions of cytokines, acute phase proteins, enzymes and their sequelae are addressed in the context of conventional periodontal therapy and its outcome with a modulatory role on metabolic diseases. Applications for the role of nutritional and therapeutic antioxidants as adjuncts in diseases with a distinctly prooxidant profile are discussed. Accurate therapeutic targeting as an adjunct to conventional periodontal treatment in this context, for mutual benefit to subjects with periodontitis and cardiometabolic diseases is a challenge.

Osteoblastic responses to LPS, glucose-oxidised LDL and minocycline: therapeutic targets for periodontal and cardiometabolic diseases.

OBJECTIVES: To study redox responses of cultured osteoblasts, mediated by bacterial lipopolysaccharide (LPS), glucose (G), glucose-oxidised low density lipoprotein (GLDL) and minocycline (M) using radiolabelled steroid markers of redox status and wound healing. The clinical relevance of this concept in periodontitis patients with cardiometabolic risk markers is addressed. METHODS: A well differentiated osteoblastic cell-line was cultured in Eagle's MEM in confluent monolayer, in 24 well multiwell plates. Radiolabelled testosterone was used as the steroid substrate. Experiments were set up with controls in the absence of agents, optimal concentrations (previously determined) of G, GLDL, LPS, M, GLDL+LPS and the latter combined with M (n = 8). At the end of a 24h incubation period, the reaction was terminated and the medium analysed for yields of the steroid metabolite 5α-dihydrotestosterone (DHT), the redox marker relevant to wound healing, the weaker androgen 4-androstenedione (4-A) and the diols. Analysis entailed thin layer chromatography and radioisotope scanning. RESULTS: The yields of DHT showed 1.4-fold and 2.3-fold decreases in response to GLDL and LPS respectively and a 1.3-fold reduction in response to the combination, when compared with controls in the absence of agents. Minocycline stimulated the yield of DHT by 1.4-fold, and when combined with GLDL+LPS, the decreased yield was overcome and raised to 2-fold above the combination in response to the addition of minocycline (n = 8; p < 0.001), when compared with controls. The trends in the yields of 4-A and diols were inversely related to each other with increases and decreases over controls respectively, in keeping with enzymic pathways. CONCLUSIONS: Decreased yields of the oxidative stress marker DHT in response to LPS, G and GLDL were overcome in the presence of minocycline, which demonstrates its potential role as an adjunctive therapeutic agent in an environment of oxidative stress. These applications could be extrapolated to periodontal disease and co-existing cardiometabolic risk markers, in the context of its antiinflammatory and antioxidant actions relevant to healing. In this paper, recent patents relevant to adjunctive therapeutic management of periodontal disease co-existing with cardiometabolic risk markers are addressed. There have been significant advances in therapeutic interventions for overcoming oxidative stress-inducing mechanisms that are common to these disease entities.

Anabolic Actions of the Regenerative Agent Enamel Matrix Derivative (EMD) in Oral Periosteal Fibroblasts and MG 63 Osteoblasts, Modulation by Nicotine and Glutathione in a Redox Environment.

Our study seeks to explore anabolic effects of a periodontal regenerative agent enamel matrix derivative (EMD). Its modulation by nicotine and the anti-oxidant glutathione (GSH) are investigated in human periosteal fibroblasts (HPF) and MG63 osteoblasts. Androgen biomarkers of oxidative stress and healing, resulting from radiolabeled androgen substrates are assayed. This in vitro model simulates a redox environment relevant to the periodontal lesion. It aims to confirm the hypothesis that EMD is an effective regenerative agent in a typically redox environment of the periodontal lesion. Monolayer cultures of MG63 osteoblasts and HPF established in culture medium are incubated with androgen substrates, and optimal concentrations of EMD, nicotine and GSH, alone and in combination. EMD significantly enhances yields of 5α-dihydrotestosterone (DHT) an effective bioactive metabolite, alone and in combination with GSH, to overcome oxidative effects of nicotine across cultures. The 'in vitro' findings of this study could be extrapolated to "in vivo" applications of EMD as an adjunctive regenerative therapeutic agent in an environment of chronic inflammation and oxidative stress. Increased yields of DHT implicated in matrix synthesis and direct antioxidant capacity, confirm the potential applications for enamel matrix derivative in periodontal regenerative procedures.

Association of periodontitis with rheumatoid arthritis and atherosclerosis: Novel paradigms in etiopathogeneses and management?

There is increasing documentation of a link between inflammatory periodontal disease affecting the supporting structure of teeth, rheumatoid arthritis, and coronary artery disease. Periodontitis is initiated predominantly by Gram-negative bacteria and progresses as a consequence of the host inflammatory response to periodontal pathogens. Lipopolysaccharide, a cell wall constituent stimulates the production of inflammatory cytokines via the activation of signaling pathways perpetuating inflammatory pathogenesis in a cyclical manner in susceptible individuals; with an element of autoimmune stimulation, not dissimilar to the sequential events seen in RA. Periodontitis, also implicated as a risk factor for cardiovascular disease, promotes mechanisms for atherosclerosis by enhancing an imbalance in systemic inflammatory mediators; more direct mechanisms attributed to microbial products are also implicated in both RA and atherogenesis. Severe periodontal disease characterized by clinical and radiographic parameters has been associated with ischemic stroke risk, significant levels of C-reactive protein and serum amyloid A, amongst others common to both periodontitis and atherosclerosis. Existing data supports the hypothesis that persistent localized infection in periodontitis may influence systemic levels of inflammatory markers and pose a risk for RA and atherosclerosis. A common nucleus of activity in their pathogeneses provides novel paradigms of therapeutic targeting for reciprocal benefit.

Oxidative stress induced mechanisms in the progression of periodontal diseases and cancer: a common approach to redox homeostasis?

There is documented evidence of significant associations between cancer of the lung, kidney, pancreas, hematological and oral cancers and periodontal diseases of the supporting structures of the teeth. Enhanced lipid peroxidation, raised levels of TBARS and the oxidative stress marker malondealdehyde have been detected in breast cancer with reduced antioxidant capacity, also characteristic of periodontal diseases. Antioxidants could overcome this deficit and attenuate disease progression by down regulating glutathione detoxification/redox buffering system and inhibiting key transcription factors. Periodontal disease may be a critical marker of a susceptible immune system, or initiate cancer risk with a pro-oxidant inflammatory profile.

Relevance of nutritional antioxidants in metabolic syndrome, ageing and cancer: potential for therapeutic targeting.

Diet and nutrition have played an important role in maintaining physiological homeostasis. Recent literature emphasizes potential therapeutic effects of micronutrients found in natural products, indicating positive applications for controlling the pathogenesis of chronic diseases driven by an inflammatory nidus. Nutritional compounds which display anti-inflammatory and antioxidant effects have specific applications in preventing oxidative stress induced injury which characterizes their pathogenesis. Patient control over diet and disease has been demonstrated in diabetes mellitus, cardiovascular disease, rheumatology, carcinogenesis and other diseases. Polyphenolic compounds are ubiquitous dietary components, mainly flavonoids and tannins. Specific polyphenols are effective in scavenging reactive oxygen and reactive nitrogen species. They are able to modulate genes associated with metabolism, stress defence, drug metabolizing enzymes, detoxification and transporter proteins. Their overall effect is protective in overcoming damaging effects of chronic diseases and in delaying the degenerative effects of ageing. The mechanisms involved in radical scavenging activity are complex, determined by the structure of the compound, redox status of the environment and interactions with other agents. Atherogenic dyslipidaemia associated with a pro-inflammatory pro-thrombotic state in metabolic syndrome and related risk of fatty liver, arthritis, neurodegenerative disorders and certain types of cancers are ideal therapeutic targets for bioactive phytochemicals which can combat oxidative stress induced damage at a sub-cellular level. It is relevant that purified micronutrients isolated from natural products may be less effective than a combination seen in the natural product due to synergistic effects of interacting agents. Some of these mechanisms and potential therapeutic targets are discussed.

Redox status in periodontal and systemic inflammatory conditions including associated neoplasias: antioxidants as adjunctive therapy?

The aetiopathogenesis of periodontal diseases is initiated by microbial biofilm which could lead to a hyperinflammatory status in aggressive forms of the disease; and cause an imbalance in the redox status, resulting in oxidative stress-induced damage. There is increasing documentation of the link between periodontal and other inflammatory diseases driven by a pro-oxidant profile. This could impose a significant systemic loading of reactive oxygen species relevant to metabolic, arthritic, age related and neoplastic diseases. They demonstrate similar markers of risk / oxidative stress induced injury during disease progression which abate in response to treatment. In certain aggressive forms of periodontal diseases resulting in a substantial systemic pro-oxidant profile, the co-existence of systemic diseases with a similar inflammatory pathogenesis could lead to progressive tissue / organ damage fuelled by the same process. Some of the common mechanisms involved are discussed, relevant to periodontal, metabolic and rheumatoid diseases, pregnancy and the foetus, age related changes and certain neoplasias which have been recently linked to periodontal disease progression. In view of a distinct pro-oxidant profile in severe cases there may a role for selective use of antioxidant adjuncts with suitable therapeutic targeting. It is relevant that periodontal diseases are associated with the above diseases and a small but significant overall cancer risk which persists in non-smokers. Periodontal disease may be a useful marker of a susceptible immune system, or directly affect the progression of systemic diseases due to inflammatory loading. Formulation of therapeutic agents shown to have efficacy in this context, with accurate targeting is a challenge.

Effect of soft laser and bioactive glass on bone regeneration in the treatment of bone defects (an experimental study).

This study aimed to investigate the influence of low-power gallium-aluminium-arsenide (GaAlAs) laser [830 nm, continuous wave (CW), 40 mW and fluence 4 J/cm(2)] on the healing of surgically created bone defects in rats treated with bioactive glass graft material. Surgical bone defects were created in the mandibles of 36 Wistar rats divided into two groups, each consisting of 18 rats. Group I was treated with bioactive glass plus laser irradiation. Group II was treated with graft material only. The animals were killed at 4 weeks, 8 weeks and 12 weeks postoperatively for histological examination. Laser irradiation had significantly accelerated bone healing at 4 weeks and 8 weeks in comparison with that at the sites not irradiated. However at 12 weeks, complete healing of the defects had occurred with no difference detected. Our results have confirmed the positive effect of soft laser in accelerating bone regeneration.

Effect of soft laser and bioactive glass on bone regeneration in the treatment of infra-bony defects (a clinical study).

This study aimed to investigate the influence of low-power 830 nm gallium-aluminium-arsenide (GaAlAs) laser [continuous wave (CW) 40 mW and fluence 4 J/cm(2), with total energy density of 16 J/cm(2)] on the healing of human infra-bony defects treated with bioactive glass graft material. Twenty patients with chronic periodontitis and bilateral infra-bony defects were included. Using a split mouth design, we treated 20 defects with bioactive glass plus laser irradiation during surgical procedures and on days 3, 5, 7 postoperatively; 20 contra-lateral defects were treated with bioactive glass only. Clinical probing pocket depths, clinical attachment levels and standardized periapical radiographs were recorded at baseline and at 3 months and 6 months postoperatively. At 3 months there was a statistically significant difference between the laser and non-laser sites in the parameters investigated. However, at 6 months, no difference was observed. Our results have confirmed the positive effect of soft laser in accelerating periodontal wound healing.

Periodontal diseases and rheumatoid arthritis: a coincident model for therapeutic intervention?

There are remarkable similarities in the pathogenesis of periodontal diseases and rheumatoid arthritis. The mechanisms that drive antigen induced sequelae of oxidative stress are discussed in this review. A poorly modulated inflammatory response drives both diseases resulting in oxidative stress induced tissue injury. Immune complex formation in response to the periodontal pathogen Porphyromonas gingivalis triggering the production of ROS in both gingivae and synovium of RA patients has been reported. Elevated antibody levels to several periodontal pathogens in RA patients has implications on both RA and periodontal diseases. Periodontal patients are challenged individuals representing a multifactorial aetiopathogenesis with potential for therapeutic intervention in the context of free radical damage. Subjects with moderate to severe periodontal bone loss are significantly more likely than healthy individuals to have several co-existing systemic conditions resulting in ROS mediated damage. There is potential for dual induction of periodontal disease by existing inflammatory mechanisms of systemic diseases rather than exacerbation of low grade inflammation only; emphasizing the relevance of reducing inflammatory burden for disease control. Therapeutic strategies based on disease mechanisms include combined low dose non-steroidal anti-inflammatory drugs and doxycycline for synergistic reduction of matrix metalloproteinase activity in periodontal tissues and RA; sub-optimal dosing with CMT-8 and a biphosphonate clodronate to reduce pathologically elevated levels of MMPs, elastase and to restore alveolar bone in experimental periodontits demonstrating dual applications. Therapeutic interventions relevant to both diseases discussed in this review, have scope for a double hit in periodontal patients with co-existing RA and vice versa.

The influence of cholesterol, progesterone, 4-androstenedione and testosterone on the growth of Treponema denticola ATCC 33520 in batch cultures.

Previously, we have shown that reference and freshly isolated Treponema denticola cultures are capable of metabolising cholesterol, progesterone, 4-androstenedione and testosterone by means of 5alpha-reductase, 3beta-and 17beta-hydroxysteroid dehydrogenase activity [Clark DT, Soory M. The metabolism of cholesterol and certain hormonal steroids by Treponema denticola. Steroids. 2006;71:352-63. ]. The aim of the work presented in this paper was to investigate the modulation of T. denticola growth in batch cultures by these steroids, using T. denticola ATCC 33520 as a model system. Growth curves were summarised using statistics based on optical density and protein yield. Cholesterol was found to stimulate growth at concentrations of 10 and 25microg/mL. Certain hormonal steroids inhibited the maximum achievable optical density at concentrations of 1 and 10microg/mL while the minimum concentration shown to inhibit protein yield was 0.001microg/mL of progesterone. The potential of the hormonal steroids to inhibit growth was in the order of progesterone, 4-androstenedione and testosterone.

Oxidant/antioxidant interactions of nicotine, Coenzyme Q10, Pycnogenol and phytoestrogens in oral periosteal fibroblasts and MG63 osteoblasts.

BACKGROUND: There is a growing awareness that oxidative stress may play a role in periodontal disease. The aim of this investigation was to evaluate potential oxidant/antioxidant interactions of nicotine with antioxidants (Coenzyme Q10 (CoQ), Pycnogenol and phytoestrogens in a cell culture model. METHODS: Duplicate incubations of human periosteal fibroblasts and osteoblasts were performed with 14C-testosterone as substrate, in the presence or absence of CoQ (20 microg/ml), Pycnogenol (150 microg/ml), and phytoestrogens (10 and 40 microg/ml), alone and in combination with nicotine (250 microg/ml). At the end of a 24-h incubation period, the medium was solvent extracted and testosterone metabolites were separated by thin-layer chromatography and quantified using a radioisotope scanner. RESULTS: The incubations of osteoblasts and periosteal fibroblasts with CoQ, Pycnogenol or phytoestrogens stimulated the synthesis of the physiologically active androgen DHT, while the yields of DHT were significantly reduced in response to nicotine compared to control values (p<0.001 for phytoestrogens). The combination of nicotine with CoQ, Pycnogenol or phytoestrogens increased the yields of DHT compared with incubation with nicotine alone in both cell types. CONCLUSION: This investigation suggests that the catabolic effects of nicotine could be reversed by the addition of antioxidants such as CoQ or Pycnogenol and phytoestrogens.

The metabolism of cholesterol and certain hormonal steroids by Treponema denticola.

The aim was to investigate whether reference cultures and fresh isolates of Treponema denticola are able to 5alpha-reduce and further metabolise testosterone, 4-androstenedione, progesterone, corticosterone, cortisol or cholesterol. Two reference and five freshly isolated cultures of T. denticola were incubated with either radiolabeled or unlabeled steroid substrates; in the first case products were identified by thin layer chromatography and in the latter by gas chromatography-mass spectroscopy. All the substrates were 5alpha-reduced. Both reference cultures and fresh isolates of T. denticola presented 3beta- and 17beta-hydroxy steroid dehydrogenase activity. It was concluded that T. denticola was capable of steroid metabolism and hypotheses are discussed regarding the in vivo function of this metabolism including, T. denticola utilising host supplied steroids as growth factors and T. denticola steroid metabolism acting as a virulence factor.