Hypochlorous Acid and Taurine-N-Monochloramine in Periodontal Diseases

Insights into Intra Periodontal Pocket Pathogenesis, Treatment, In Vitro-In Vivo Models, Products and Patents, Challenges and Opportunity

Periodontal disease is a multifactorial pathogenic condition involving microbial infection, inflammation, and various systemic complications. Here, a systematic and comprehensive review discussing key-points such as the pros and cons of conventional methods, new advancements, challenges, patents and products, and future prospects is presented. A systematic review process was adopted here by using the following keywords: periodontal diseases, pathogenesis, models, patents, challenges, recent developments, and 3-D printing scaffolds. Search engines used were "google scholar", "web of science", "scopus", and "pubmed", along with textbooks published over the last few decades. A thorough study of the published data rendered an accurate and deep understanding of periodontal diseases, the gap of research so far, and future opportunities. Formulation scientists and doctors need to be interconnected for a better understanding of the disease to prescribe a quality product. Moreover, prime challenges (such as a lack of a vital testing model, scarcity of clinical and preclinical data, products allowing for high drug access to deeper tissue regions for prolonged residence, lack of an international monitoring body, lack of 4D or time controlled scaffolds, and lack of successful AI based tools) exist that must be addressed for designing new quality products. Generally, several products have been commercialized to treat periodontal diseases with certain limitations. Various strategic approaches have been attempted to target certain delivery regions, maximize residence time, improve efficacy, and reduce toxicity. Conclusively, the current review summarizes valuable information for researchers and healthcare professional to treat a wide range of periodontal diseases.

Tolerability of N-chlorotaurine in comparison with routinely used antiseptics: an in vitro study on chondrocytes

BACKGROUND

Currently, povidone-iodine (PVP-I) and hydrogen peroxide (H2O2) are frequently used antiseptics in joint infections, but the cytotoxic effects of these solutions are already reported. N-chlorotaurine (NCT) shows a broad-spectrum bactericidal activity and is well tolerated in various tissues, but its effect on human chondrocytes is unknown. The purpose of this study was to assess the cytotoxic effect of NCT, PVP-I, and H2O2 on human chondrocytes compared to a control group in an in vitro setting to get first indications if NCT might be a promising antiseptic in the treatment of septic joint infections for the future.

MATERIAL AND METHODS

Chondrocytes extracted from human cartilage were incubated with various concentrations of NCT, PVP-I, and H2O2 for 5 and 30 min respectively. EZ4U cell viability kit was used according to the manufacturer's recommendations determining cell viability. To assess cell viability based on their nuclear morphology, cells were stained with acridine-orange and identified under the fluorescence microscope.

RESULTS

EZ4U kit showed after 5 and 30 min of incubation a significant decrease in cell viability at NCT 1%, NCT 0.1%, PVP-I, and H2O2, but not for NCT 0.001% and NCT 0.01%. Acridine-orange staining likewise presented a significant decrease in vital cells for all tested solutions except NCT 0.001% and NCT 0.01% after 5 and 30 min of incubation.

CONCLUSION

Our results demonstrate that NCT is well tolerated by chondrocytes in vitro at the tested lower NCT concentrations 0.01% and 0.001% in contrast to the higher NCT concentrations 1% and 0.1%, PVP-I (1.1%), and H2O2 (3%), for which a significant decrease in cell viability was detected. Considering that the in vivo tolerability is usually significantly higher, our findings could be an indication that cartilage tissue in vivo would tolerate the already clinically used 1% NCT solution. In combination with the broad-spectrum bactericidal activity, NCT may be a promising antiseptic for the treatment of septic joint infections.

In vitro cytotoxicity and antibacterial activity of hypochlorous acid antimicrobial agent

Background/purpose

Bacteria-associated oral diseases such as dental caries and periodontitis are widespread epidemics that cause oral pain and loss of function. The purpose of this study was to evaluate the in vitro cytotoxicity and antibacterial activity of different concentrations of hypochlorous acid (HOCl).

Materials and methods

Five different concentrations (100, 200, 300, 400, and 500 ppm) of HOCl were evaluated for their antimicrobial efficacy against Gram-negative (A. actinomycetcmcomitans and P. gingivalis) and Gram-positive bacteria (S. mutans and S. sanguinis) after treatment for 1 and 10 min. Sodium hypochlorite (NaOCl) and chlorhexidine (CHX) were used as positive controls. In addition, HOCl was examined for L929 cytotoxicity and RAW 264.7 growth.

Results

The bacteriostatic ratio of NaOCl was comparable to that of CHX and significantly (P < 0.05) higher than that of all HOCl solutions. Higher HOCl concentration had significantly (P < 0.05) higher antibacterial effect, and the bacteriostatic ratio of 10 min treatment was slightly higher than that of 1 min treatment. CHX and NaOCl seeded into L929 cells resulted in low cell viability with only 30-39%, much significantly (P < 0.05) lower than all HOCl groups (greater than 80%). All HOCl solutions met the recommendations of ISO 10993-5 and showed no cytotoxicity, although there was a concentration-dependent decrease in cell viability. All antimicrobial agents showed the same trend of response to RAW 264.7 as L929.

Conclusion

Within the limit of this study, 400 ppm HOCl disinfectant may be a potential antimicrobial candidate for mouthwash, endodontic irrigants, and periodontitis treatment.

Construction and Application of Fluorescent Probes with Imine Protective Groups for Hypochlorite Detection

Several fluorescent probes have been designed to detect ClO- in biological systems based on the isomerization mechanism of C = N bonds. Particularly, fluorescein has emerged as an important fluorophore for detecting ClO- because of its unique properties. Previously, we introduced the fluorescein analog F-1 with an active aldehyde group. In this study, two ClO- fluorescent sensors (F-2 and F-3) with imine groups were designed and synthesized using diaminomaleonitrile and 2-hydrazylbenzothiazole as amines. The electron cloud distribution of F-2 and F-3 in ground and excited states was explored via Gaussian calculations, reasonably explaining their photophysical properties. The fluorescence detection of ClO- in solution using the two probes (F-2 and F-3) was realized based on the mechanism of imine deprotection with ClO-. NaClO concentration titration demonstrated that the colorimetric detection of ClO- with the naked eye could be achieved using both F-2 and F-3. However, after adding ClO-, the fluorescence intensity of probe F-2 increased, whereas that of probe F-3 first decreased and then increased. Probes F-2 and F-3 exhibited good selectivity, anti-interference capability, and sensitivity, with the detection limits of 169.95 and 37.30 µM, respectively. Owing to their low cell toxicity, probes F-2 and F-3 can be applied to detect ClO- in vivo. The design approach adopted in this study will further advance the future development of ClO- chemical probes through the removal of C = N bond isomerization.

Deuterohemin-Ala-His-Thr-Val-Glu-Lys (DhHP-6) Mimicking Enzyme as Synergistic Antioxidant and Anti-Inflammatory Material for Periodontitis Therapy

Periodontitis is an inflammatory disease induced by plaque microorganisms. In the clinic, antibiotic assistant periodontal mechanical therapy is the most effective therapy for the treatment of periodontitis. However, the drug resistance of the antibiotics and the repeated coming and diminishing of the disorder of oxidation-reduction balance in the inflammatory tissue could not meet the high requirements for periodontic health control in long periods. Deuterohemin-ala-his-thr-val-glu-lys (DhHP-6) is a biomimetic oxidase-mimicking enzyme that simulates the reactive oxygen radical scavenger function of heme by synthesizing the new molecular material following the key structure and amino acid sequence of heme. In this article, we report the antioxidant and anti-inflammatory properties of DhHP-6 by building a inflammatory model for human gingival fibroblasts (HGFs) stimulated by lipolysaccharide (LPS) and its effects on periodontitis in Wistar rats. DhHP-6 reduced the oxidative stress of HGFs by increasing the amount of the reductase species of glutathione (GSH) and catalase (CAT) while decreasing the amount of oxidase species of malonaldehyde (MDA) and reactive oxygen species (ROS). DhHP-6 had a dose-dependent protective effect on alveolar bone absorption in rats with periodontitis, enhanced antioxidant capacity, and reduced inflammation. As determined by Micro-CT scanning, DhHP-6 reduced alveolar bone loss and improved the bone structure of the left maxillary first molar of rats. There were no obvious morphological and histological differences in the rat organs with or without DhHP-6 treatment. These results suggest that DhHP-6 can be used to treat periodontitis by increasing the expression levels of antioxidant enzymes and antioxidants in systemic and local tissues, thereby reducing levels of oxidation products and cyto-inflammatory factors. The synergistic antioxidant and anti-inflammatory effects of DhHP-6 suggest that there are promising applications of this biomimetic enzyme molecular material for the next generation of agents for periodontitis therapy.

Hypochlorous Acid: From Innate Immune Factor and Environmental Toxicant to Chemopreventive Agent Targeting Solar UV-Induced Skin Cancer

A multitude of extrinsic environmental factors (referred to in their entirety as the 'skin exposome') impact structure and function of skin and its corresponding cellular components. The complex (i.e. additive, antagonistic, or synergistic) interactions between multiple extrinsic (exposome) and intrinsic (biological) factors are important determinants of skin health outcomes. Here, we review the role of hypochlorous acid (HOCl) as an emerging component of the skin exposome serving molecular functions as an innate immune factor, environmental toxicant, and topical chemopreventive agent targeting solar UV-induced skin cancer. HOCl [and its corresponding anion (OCl-; hypochlorite)], a weak halogen-based acid and powerful oxidant, serves two seemingly unrelated molecular roles: (i) as an innate immune factor [acting as a myeloperoxidase (MPO)-derived microbicidal factor] and (ii) as a chemical disinfectant used in freshwater processing on a global scale, both in the context of drinking water safety and recreational freshwater use. Physicochemical properties (including redox potential and photon absorptivity) determine chemical reactivity of HOCl towards select biochemical targets [i.e. proteins (e.g. IKK, GRP78, HSA, Keap1/NRF2), lipids, and nucleic acids], essential to its role in innate immunity, antimicrobial disinfection, and therapeutic anti-inflammatory use. Recent studies have explored the interaction between solar UV and HOCl-related environmental co-exposures identifying a heretofore unrecognized photo-chemopreventive activity of topical HOCl and chlorination stress that blocks tumorigenic inflammatory progression in UV-induced high-risk SKH-1 mouse skin, a finding with potential implications for the prevention of human nonmelanoma skin photocarcinogenesis.

Sensing Hypochlorite or pH variations in live cells and zebrafish with a novel dual-functional ratiometric and colorimetric chemosensor

Both HClO and pH are essential players in multiple biological processes, which thus need to be controlled properly. Dysregulated HClO or pH correlates with many diseases. To meet these challenges, we need to develop highly competent probes for monitoring them. Over the years, despite a rich history of the development of HClO or pH probes, those that can do both jobs are still deficient. Herein, we present a novel dual-functional chemosensor, CMHN, which exhibits a blue and red shift of its fluorescence emission upon reacting with HClO or OH^-, respectively. CMHN was successfully harnessed in the imaging detection of HClO or OH^- in aqueous solutions, live cells, and zebrafish. Results indicated CMHN can detect HClO with high sensitivity (LOD -132 nM), a quick response time (<70 s), and high selectivity over dozens of interfering species through a colorimetric and ratiometric response. Besides, CMHN can probe pH changes sensitively and reversibly. Its working mechanism was verified by DFT calculations. These superior features make CMHN excel among the HClO or pH probes reported so far. Taken together, CMHN replenishes the deficiency in currently developed HClO or pH probes and paves the way for developing multifunctional HClO or pH probes in the future.

Modifications of IL-6 by Hypochlorous Acids: Effects on Receptor Binding

Interleukin-6 (IL-6) has been implicated in the pathogenesis of inflammatory events including those seen with COVID-19 patients. Positive clinical responses to monoclonal antibodies directed against IL-6 receptors (IL-6Rs) suggest that interference with IL-6-dependent activation of pro-inflammatory pathways offers a useful approach to therapy. We exposed IL-6 to hypochlorous acid (HOCl) in vitro at concentrations reported to develop in vivo. After HOCl treatment, binding of IL-6 to IL-6R was reduced in a dose-dependent manner using a bioassay with human cells engineered to provide a luminescence response to signal transduction upon receptor activation. Similar results followed the exposure of IL-6 to N-chlorotaurine (NCT) and hypobromous acid (HOBr), two other reactive species produced in vivo. SDS-PAGE analysis of HOCl-treated IL-6 showed little to no fragmentation or aggregation up to 1.75 mM HOCl, suggesting that the modifications induced at concentrations below 1.75 mM took place on the intact protein. Mass spectrometry of trypsin-digested fragments identified oxidative changes to two amino acid residues, methionine 161 and tryptophan 157, both of which have been implicated in receptor binding of the cytokine. Our findings suggest that exogenous HOCl and NCT might bring about beneficial effects in the treatment of COVID-19. Further studies on how HOCl and HOBr and their halogenated amine derivatives interact with IL-6 and related cytokines in vivo may open up alternative therapeutic interventions with these compounds in COVID-19 and other hyperinflammatory diseases.

Metabolic phenotyping of saliva to identify possible biomarkers of periodontitis using proton nuclear magnetic resonance

AIM

The aim of this study was to propose biomarker candidates for periodontitis via untargeted metabolomics analysis.

MATERIALS AND METHODS

Metabolic profiling was performed using saliva samples from 92 healthy controls (H) and 129 periodontitis patients (P) in the discovery cohort using proton nuclear magnetic resonance spectroscopy. Random forest was applied to identify metabolites that significantly differentiated the control group from the periodontitis group. Candidate metabolites were then validated in an independent validation cohort.

RESULTS

In the discovery set, the metabolic profiles of the P group were clearly separated from those of the H group. A total of 31 metabolites were identified in saliva, and 7 metabolites were selected as candidate biomarkers. These metabolites were further confirmed in the validation set. Ethanol, taurine, isovalerate, butyrate, and glucose were finally confirmed as biomarkers. Furthermore, the biomarker panel showed more than 0.9 of the area under curve value in both discovery and validation sets, indicating that panels were more effective than individual metabolites for diagnosing periodontitis.

CONCLUSIONS

We identified five metabolite biomarkers that discriminated patients with periodontitis from healthy controls in two independent cohorts. These biomarkers have the potential for periodontal screening, detection of periodontitis, and monitoring of the outcome of periodontal therapy.

The development of a highly selective fluorescent probe for the rapid detection of HClO in living cells and zebrafish

A new turn-on fluorescent probe, BM-HA, for the rapid detection of HClO in living cells and zebrafish is proposed, and DFT/TDDFT calculations provide insights into the optical properties of the BM-HA probe.

Role of taurine, its haloamines and its lncRNA TUG1 in both inflammation and cancer progression. On the road to therapeutics? (Review)

For one century, taurine is considered as an end product of sulfur metabolism. In this review, we discuss the beneficial effect of taurine, its haloamines and taurine upregulated gene 1 (TUG1) long non‑coding RNA (lncRNA) in both cancer and inflammation. We outline how taurine or its haloamines (N‑Bromotaurine or N‑Chlorotaurine) can induce robust and efficient responses against inflammatory diseases, providing insight into their molecular mechanisms. We also provide information about the use of taurine as a therapeutic approach to cancer. Taurine can be combined with other chemotherapeutic drugs, not only mediating durable responses in various malignancies, but also circumventing the limitations met from chemotherapeutic drugs, thus improving the therapeutic outcome. Interestingly, the lncRNA TUG1 is regarded as a promising therapeutic approach, which can overcome acquired resistance of cancer cells to selected strategies. In this regard, we can translate basic knowledge about taurine and its TUG1 lncRNA into potential therapeutic options directed against specific oncogenic signaling targets, thereby bridging the gap between bench and bedside.

Multimodal Molecular Imaging Demonstrates Myeloperoxidase Regulation of Matrix Metalloproteinase Activity in Neuroinflammation

Myeloperoxidase (MPO) has paradoxically been found to be able to both activate matrix metalloproteinases (MMPs) as well as inhibit MMPs. However, these regulatory effects have not yet been observed in vivo, and it is unclear which pathway is relevant in vivo. We aim to track MPO regulation of MMP activity in living animals in neuroinflammation. Mice induced with experimental autoimmune encephalomyelitis (EAE), a mouse model of neuroinflammation and multiple sclerosis, were treated with either the MPO-specific inhibitor 4-aminobenzoic acid hydrazide or saline as control. Mice underwent concurrent magnetic resonance imaging (MRI) with the MPO-specific molecular imaging agent MPO-Gd and fluorescence molecular tomography (FMT) with the MMP-targeting agent MMPsense on day 12 after induction. Biochemical and histopathological correlations were performed. Utilizing concurrent MRI and FMT imaging, we found reduced MMP activity in the brain with MPO inhibition, demonstrating MPO activity positively regulates MMP activity in vivo. In vivo MMPSense activation and MMP-9 activity correlated with MPO-Gd⁺ lesion volume and disease severity. This was corroborated by in vitro assays and histopathological analyses that showed MMP activity and MMP-9⁺ cells correlated with MPO activity and MPO⁺ cells. In conclusion, multimodal molecular imaging demonstrates for the first time MPO regulation of MMP activity in living animals. This approach could serve as a model to study the interactions of other biologically interesting molecules in living organisms.

Effect of smear layer deproteinization on bonding of self-etch adhesives to dentin: a systematic review and meta-analysis

OBJECTIVES

The aim of this systematic review was to critically analyze previously published studies of the effects of dentin surface pretreatment with deproteinizing agents on the bonding of self-etch (SE) adhesives to dentin. Additionally, a meta-analysis was conducted to quantify the effects of the above-mentioned surface pretreatment methods on the bonding of SE adhesives to dentin.

MATERIALS AND METHODS

An electronic search was performed using the following databases: Scopus, PubMed and ScienceDirect. The online search was performed using the following keywords: 'dentin' or 'hypochlorous acid' or 'sodium hypochlorite' and 'self-etch adhesive.' The following categories were excluded during the assessment process: non-English articles, randomized clinical trials, case reports, animal studies, and review articles. The reviewed studies were subjected to meta-analysis to quantify the effect of the application time and concentration of sodium hypochlorite (NaOCl) and hypochlorous acid (HOCl) deproteinizing agents on bonding to dentin.

RESULTS

Only 9 laboratory studies fit the inclusion criteria of this systematic review. The results of the meta-analysis revealed that the pooled average microtensile bond strength values to dentin pre-treated with deproteinizing agents (15.71 MPa) was significantly lower than those of the non-treated control group (20.94 MPa).

CONCLUSIONS

In light of the currently available scientific evidence, dentin surface pretreatment with deproteinizing agents does not enhance the bonding of SE adhesives to dentin. The HOCl deproteinizing agent exhibited minimal adverse effects on bonding to dentin in comparison with NaOCl solutions.

Rhodol Derivatives as Selective Fluorescent Probes for the Detection of HgII Ions and the Bioimaging of Hypochlorous Acid

Two sensors, 1 with a spirolactone group and 2 with a spirolactam group containing a phenyl isothiocyanate moiety, based on rhodol, were designed and synthesized in order to obtain materials with excellent optical properties for the detection of environmentally and biologically important Hg2+ and hypochlorous acid (HClO) ions. The crystal structure of 1 revealed two moieties, a rhodamine-like portion with a spirolactone and a fluorescein-like portion without a spirolactone. In the absence of analyte, 1 produced an optical output with a maximum absorption and emission at 475 and 570 nm, respectively, which was attributed to the fluorescein-like moiety without a spirolactone. In contrast, the rhodamine-like moiety containing a spirolactone was activated by the addition of H+ or Hg2+ ions, and 1 yielded new absorption and emission peaks at 530 and 612 nm, respectively. Further functionalization with a phenyl isothiocyanate group afforded 2, a fluorescent probe for HClO. High selectivity and sensitivity towards the hypochlorite ion were anticipated, owing to the stoichiometric and irreversible formation of a thiosemicarbazide group, which led to dramatic fluorescence responses. With good functionality at physiological pH, probe 2 was successfully used to image HClO in HeLa cells.

Elevated Neutrophil Elastase in Tears of Ocular Graft-Versus-Host Disease Patients

PURPOSE

To investigate the levels of neutrophil elastase (NE), matrix metalloproteinases (MMPs), and myeloperoxidase (MPO) in tear washes of patients with ocular graft-vs-host disease (oGVHD).

DESIGN

Case-control study.

METHODS

Based on established criteria, oGVHD patients (n = 14; 28 eyes) and age-/sex-matched healthy controls (n = 14; 28 eyes) were enrolled. Tear washes were collected and analyzed for NE using a single-analyte enzyme-linked immunosorbent assay (ELISA). MMPs (1, 2, 3, 7, 8, 9, 12), MPO, and tissue inhibitor of matrix metalloproteinase (TIMP)-1 were analyzed using multianalyte bead-based ELISA assays. Total MMP activity was measured using a fluorimetric assay. Correlation studies were performed between NE, MMP-8, MMP-9, and MPO within study groups.

RESULTS

NE, MMP-8, MMP-9, and MPO levels were elevated in oGVHD tears when compared with controls (P < .0001). NE was the most elevated analyte. MMP activity was higher and TIMP-1 levels were lower in oGVHD than in control (P < .0001). In oGVHD, NE significantly correlated with MMP-8 (r = 0.92), MMP-9 (r = 0.90), and MPO (r = 0.79) (P < .0001). MMP-8 correlated with MMP-9 (r = 0.96, P < .0001), and MPO (r = 0.60, P = .001). MMP-9 correlated with MPO (r = 0.55, P = .002). In controls, NE, MMP-9, and MPO significantly correlated with each other (P < .0001).

CONCLUSIONS

The marked increase in NE in oGVHD tears that correlated strongly with elevated MMP-8, MMP-9, and MPO suggests a common neutrophilic source and provides evidence of neutrophil activity on the ocular surface of oGVHD patients.

Lack of adjunctive effect of 0.1% sodium hypochlorite mouthwash combined to full-mouth ultrasonic debridement on supragingival plaque, gingival inflammation, and subgingival microbiota: A randomized placebo-controlled 6-month trial

To test the adjunctive effect of 0.1% sodium hypochlorite (NaOCl) mouthwash combined to full‐mouth ultrasonic debridement (FMUD) on reducing supragingival plaque, gingival inflammation, and microbial pathogens. In this 6‐month double‐blinded randomized clinical trial, individuals with gingivitis were assigned to test (n = 16) or placebo group (n = 16) and received FMUD followed by rinsing with 0.1% NaOCl (test) or distilled water (placebo), respectively, twice a day for 1 month. Full‐mouth periodontal examination was performed at baseline, 1, 3, and 6 months posttherapy, and subgingival plaque samples were obtained at the same time points and analysed for their composition by checkerboard. Differences between groups over time were examined by Student t test, Mann–Whitney, generalized linear model, and Friedman and chi‐square tests. Both therapeutic protocols resulted in significant clinical improvement in periodontal parameters over time, except for probing depth and attachment level, which had a slight mean increase of 0.2 mm (p < .01). No significant differences between groups were observed for any clinical parameter (p > .05). Most species (>65%) decreased similarly in levels in both groups over time. Significant reductions in the microbial complexes were seen mainly at 1 and 3 months, but they returned to baseline levels in both groups, except for the red and yellow complexes, and other oral species, which were kept in low levels at 6 months (p < .05). A 0.1% NaOCl mouthwash did not provide additional benefits to FMUD in reducing supragingival plaque, gingivitis, and/or microbial pathogens.

Does chemical preconditioning contribute to the effectiveness of scaling and root planing? An in vitro pilot investigation

OBJECTIVES

A solution based on hypochlorite and amino acids was introduced to improve cleaning efficacy on the root surfaces. The purpose of this in vitro pilot study was to evaluate the time reduction and number of strokes required to clean untreated root surfaces in vitro.

METHODS

Sixty extracted human teeth displaying areas with subgingival calculus were assigned equally to one of three treatment groups (n = 20) according to the size of occupied areas, estimated by the number of pixels. The groups were assigned to either 30 s penetration time (I) or 300 s (II) or no pretreatment application (III). The weight for instrumentation was calibrated for a M25A curette (Deppeler/Switzerland) with 500 g. A new set of tools was used for each group, and each instrument was sharpened after single use by an EasySharp Device (Deppeler/Switzerland).

RESULTS

The time (in seconds) for instrumentation was recorded as follows: Group I: 32/23.5/50 (median/first quartile/third quartile); group II: 33/20/52.5; group III: 46.5/35.5/52.3. The results for the numbers of strokes were: Group I: 18/14.3/28; group II: 18.5/13/30.5; group III: 17.5/15/25. No statistically significant differences (P < 0.05) were found between the three groups for the variables 'time' and 'number of strokes'.

CONCLUSIONS

Within the limits of this in vitro pilot study, preconditioning of the calculus on root surfaces with an alkaline solution failed to reduce the number of strokes and time of instrumentation significantly.

Effectiveness of Hypochlorous Acid to Reduce the Biofilms on Titanium Alloy Surfaces in Vitro

Chemotherapeutic agents have been used as an adjunct to mechanical debridement for peri-implantitis treatment. The present in vitro study evaluated and compared the effectiveness of hypochlorous acid (HOCl), sodium hypochlorite (NaOCl), and chlorhexidine (CHX) at eliminating Gram-negative (E. coli and P. gingivalis) and Gram-positive (E. faecalis and S. sanguinis) bacteria. The effect of irrigating volume and exposure time on the antimicrobial efficacy of HOCl was evaluated, and a durability analysis was completed. Live/dead staining, morphology observation, alamarBlue assay, and lipopolysaccharide (LPS) detection were examined on grit-blasted and biofilm-contaminated titanium alloy discs after treatment with the three chemotherapeutic agents. The results indicated that HOCl exhibited better antibacterial efficacy with increasing irrigating volumes. HOCl achieved greater antibacterial efficacy as treatment time was increased. A decrease in antimicrobial effectiveness was observed when HOCl was unsealed and left in contact with the air. All the irrigants showed antibacterial activity and killed the majority of bacteria on the titanium alloy surfaces of biofilm-contaminated implants. Moreover, HOCl significantly lowered the LPS concentration of P. gingivalis when compared with NaOCl and CHX. Thus, a HOCl antiseptic may be effective for cleaning biofilm-contaminated implant surfaces.

Molecular engineering of a dual emission near-infrared ratiometric fluorophore for the detection of pH at the organism level

A near-infrared ratiometric fluorophore (NIR-HBT) was rationally designed and constructed by expanding both the excitation and emission wavelength of the classical ratiometric fluorophore 2-(benzothiazol-2-yl)phenol (HBT) into the near-infrared region. The NIR-HBT was easily synthesized by incorporating the HBT module into the hemicyanine skeleton and showed evident NIR ratiometric fluorophore characteristics. Further application of the new fluorophore for pH detection demonstrated that NIR-HBT possesses superior overall analytical performance and NIR-HBT was successfully applied for detection of acidosis caused by inflammation in living animal tissue, which indicated the potential application value of NIR-HBT in biological imaging and sensing.

Host modulation therapy: An indispensable part of perioceutics

Traditionally, only antimicrobials have been used as the chemotherapeutic modality for the treatment of periodontitis. Though bacteria are the primary etiologic factors of periodontal diseases, yet the extent and severity of tissue destruction seen in periodontitis is determined by the host immuno-inflammatory response to these bacteria. This increasing awareness and knowledge of the host-microbial interaction in periodontal pathogenesis has presented the opportunity for exploring new therapeutic strategies for periodontitis by means of targeting host response via host-modulating agents. This has lead to the emergence of the field of "Perioceutics" i.e. the use of parmacotherapeutic agents including antimicrobial therapy as well as host modulatory therapy for the management of periodontitis. These host-modulating agents used as an adjunct tip the balance between periodontal health and disease progression in the direction of a healing response. In this article the host-modulating role of various systemically and locally delivered perioceutic agents will be reviewed.

Real-time noninvasive monitoring of in vivo inflammatory responses using a pH ratiometric fluorescence imaging probe

It is often difficult to continuously monitor and quantify inflammatory responses in vivo. These dynamic responses however are often accompanied by specific pH changes. A new ratiometric optical pH probe is developed by combining pH-sensitive (CypHer5E) and pH-insensitive (Oyster800) fluorescent dyes into nanoparticles for in vivo optical imaging. By taking the ratio of fluorescence intensities at different wavelengths, these nanosized sensors provide excellent measurement capabilities, and unique mapping, of the continuous in vivo pH changes for three different inflammation models. In each model a strong positive correlation is found between ratiometric pH changes and the corresponding inflammatory response measured by histological analyses. These results indicate that ratiometric imaging can provide a noninvasive, rapid, and highly sensitive optical readout for the pH-ratio changes in vivo. Furthermore this technique may be used to monitor the real-time dynamics of inflammatory processes.

Neutrophil collagenase, gelatinase, and myeloperoxidase in tears of patients with stevens-johnson syndrome and ocular cicatricial pemphigoid

OBJECTIVE

To investigate the levels of matrix metalloproteinases (MMPs), myeloperoxidase (MPO), and tissue inhibitor of metalloproteinase-1 (TIMP-1) in tears of patients with Stevens-Johnson syndrome (SJS) and ocular cicatricial pemphigoid (OCP).

DESIGN

Prospective, noninterventional cohort study.

PARTICIPANTS

Four SJS patients (7 eyes), 19 OCP patients (37 eyes), and 20 healthy controls who underwent phacoemulsification (40 eyes).

METHODS

Tear washes were collected from all patients and were analyzed for levels of MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-12, MPO, and TIMP-1 using multianalyte bead-based enzyme-linked immunosorbent assays. Total MMP activity was determined using a fluorometric assay. Correlation studies were performed between the various analytes within study groups.

MAIN OUTCOME MEASURES

Levels of MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-12, MPO, and TIMP-1 (in nanograms per microgram of protein) and total MMP activity (in relative fluorescent units per minute per microgram of protein) in tears; MMP-8-to-TIMP-1 ratio; MMP-9-to-TIMP-1 ratio; and the correlations between MMP-8 and MMP-9 and both MMP and MPO.

RESULTS

MMP-8, MMP-9, and MPO levels were elevated significantly in SJS and OCP tears (SJS>OCP) when compared with controls. The MMP activity was highest in SJS patients, whereas OCP patients and controls showed lower and similar activities. The TIMP-1 levels were decreased in SJS and OCP patients when compared with those in controls, with levels in OCP patients reaching significance. The MMP-8-to-TIMP-1 and MMP-9-to-TIMP-1 ratios were markedly elevated in SJS and OCP tears (SJS>OCP) when compared with those of controls. Across all study groups, MMP-9 levels correlated strongly with MMP-8 and MPO levels, and MMP-8 correlated with MPO, but it did not reach significance in SJS patients. There was no relationship between MMP-7 and MPO.

CONCLUSIONS

Because MMP-8 and MPO are produced by inflammatory cells, particularly neutrophils, the correlation data indicate that they may be the common source of elevated enzymes, including MMP-9, in SJS and OCP tears. Elevated MMP-to-TIMP ratios and MMP activity suggest an imbalance in tear MMP regulation that may explain the predisposition of these patients to demonstrate corneal melting and chronic complications associated with persistent inflammation. Myeloperoxidase in tears may be a sensitive and specific marker for the quantification of ocular inflammation.

Taurine and inflammatory diseases

Taurine (2-aminoethanesulfonic acid) is the most abundant free amino acid in humans and plays an important role in several essential biological processes such as bile acid conjugation, maintenance of calcium homeostasis, osmoregulation and membrane stabilization. Moreover, attenuation of apoptosis and its antioxidant activity seem to be crucial for the cytoprotective effects of taurine. Although these properties are not tissue specific, taurine reaches particularly high concentrations in tissues exposed to elevated levels of oxidants (e.g., inflammatory cells). It suggests that taurine may play an important role in inflammation associated with oxidative stress. Indeed, at the site of inflammation, taurine is known to react with and detoxify hypochlorous acid generated by the neutrophil myeloperoxidase (MPO)–halide system. This reaction results in the formation of less toxic taurine chloramine (TauCl). Both haloamines, TauCl and taurine bromamine (TauBr), the product of taurine reaction with hypobromous acid (HOBr), exert antimicrobial and anti-inflammatory properties. In contrast to a well-documented regulatory role of taurine and taurine haloamines (TauCl, TauBr) in acute inflammation, their role in the pathogenesis of inflammatory diseases is not clear. This review summarizes our current knowledge concerning the role of taurine, TauCl and TauBr in the pathogenesis of inflammatory diseases initiated or propagated by MPO-derived oxidants. The aim of this paper is to show links between inflammation, neutrophils, MPO, oxidative stress and taurine. We will discuss the possible contribution of taurine and taurine haloamines to the pathogenesis of inflammatory diseases, especially in the best studied example of rheumatoid arthritis.

Radiation protection following nuclear power accidents: a survey of putative mechanisms involved in the radioprotective actions of taurine during and after radiation exposure

There are several animal experiments showing that high doses of ionizing radiation lead to strongly enhanced leakage of taurine from damaged cells into the extracellular fluid, followed by enhanced urinary excretion. This radiation-induced taurine depletion can itself have various harmful effects (as will also be the case when taurine depletion is due to other causes, such as alcohol abuse or cancer therapy with cytotoxic drugs), but taurine supplementation has been shown to have radioprotective effects apparently going beyond what might be expected just as a consequence of correcting the harmful consequences of taurine deficiency per se. The mechanisms accounting for the radioprotective effects of taurine are, however, very incompletely understood. In this article an attempt is made to survey various mechanisms that potentially might be involved as parts of the explanation for the overall beneficial effect of high levels of taurine that has been found in experiments with animals or isolated cells exposed to high doses of ionizing radiation. It is proposed that taurine may have radioprotective effects by a combination of several mechanisms: (1) during the exposure to ionizing radiation by functioning as an antioxidant, but perhaps more because it counteracts the prooxidant catalytic effect of iron rather than functioning as an important scavenger of harmful molecules itself, (2) after the ionizing radiation exposure by helping to reduce the intensity of the post-traumatic inflammatory response, and thus reducing the extent of tissue damage that develops because of severe inflammation rather than as a direct effect of the ionizing radiation per se, (3) by functioning as a growth factor helping to enhance the growth rate of leukocytes and leukocyte progenitor cells and perhaps also of other rapidly proliferating cell types, such as enterocyte progenitor cells, which may be important for immunological recovery and perhaps also for rapid repair of various damaged tissues, especially in the intestines, and (4) by functioning as an antifibrogenic agent. A detailed discussion is given of possible mechanisms involved both in the antioxidant effects of taurine, in its anti-inflammatory effects and in its role as a growth factor for leukocytes and nerve cells, which might be closely related to its role as an osmolyte important for cellular volume regulation because of the close connection between cell volume regulation and the regulation of protein synthesis as well as cellular protein degradation. While taurine supplementation alone would be expected to exert a therapeutic effect far better than negligible in patients that have been exposed to high doses of ionizing radiation, it may on theoretical grounds be expected that much better results may be obtained by using taurine as part of a multifactorial treatment strategy, where it may interact synergistically with several other nutrients, hormones or other drugs for optimizing antioxidant protection and minimizing harmful posttraumatic inflammatory reactions, while using other nutrients to optimize DNA and tissue repair processes, and using a combination of good diet, immunostimulatory hormones and perhaps other nontoxic immunostimulants (such as beta-glucans) for optimizing the recovery of antiviral and antibacterial immune functions. Similar multifactorial treatment strategies may presumably be helpful in several other disease situations (including severe infectious diseases and severe asthma) as well as for treatment of acute intoxications or acute injuries (both mechanical ones and severe burns) where severely enhanced oxidative and/or nitrative stress and/or too much secretion of vasodilatory neuropeptides from C-fibres are important parts of the pathogenetic mechanisms that may lead to the death of the patient. Some case histories (with discussion of some of those mechanisms that may have been responsible for the observed therapeutic outcome) are given for illustration of the likely validity of these concepts and their relevance both for treatment of severe infections and non-infectious inflammatory diseases such as asthma and rheumatoid arthritis.

Naked-eye visible and fluorometric dual-signaling chemodosimeter for hypochlorous acid based on water-soluble p-methoxyphenol derivative

The oxidation of a simple p-methoxyphenol derivative by HClO induces an intramolecular charge transfer from the end phenyl units to the middle benzoquinone, which leads to colorimetric and fluorescent changes. This detection can be run in aqueous solution with high selectivity over other reactive oxygen species.

Differential effects of taurine treatment and taurine deficiency on the outcome of renal ischemia reperfusion injury

Taurine possesses membrane stabilization, osmoregulatory and antioxidant properties, aspects of relevance to ischemic injury. We tested the hypothesis that body taurine status is a determinant of renal ischemic injury. Accordingly, renal function and structure were examined in control (C), taurine-treated (TT) and taurine deficient (TD) rats that were subjected to bilateral renal ischemia (60 min) followed by reperfusion (IR); sham operated rats served as controls. Baseline urine osmolality was greater in the TD group than in the control and the TT groups, an effect associated with increased renal aquaporin 2 level. The IR insult reduced urine osmolality (i.e., day-1 post insult); the TD/IR group displayed a more marked recovery in urine osmolality by day-6 post insult than the other two groups. Fluid and sodium excretions were lower in the TD/IR group, suggesting propensity to retention. Histopathological examination revealed the presence of tubular necrotic foci in the C/IR group than sham controls. While renal architecture of the TD/IR group showed features resembling sham controls, the TT/IR group showed dilated tubules, which lacked immunostaining for aquaporin 2, but not 1, suggestive of proximal tubule origin. Finally, assessment of cell proliferation and apoptosis revealed lower proliferation but higher apoptotic foci in the TT/IR group than other IR groups. Collectively, the results indicate that body taurine status is a major determinant of renal IR injury.

Small molecular, macromolecular, and cellular chloramines react with thiocyanate to give the human defense factor hypothiocyanite

Thiocyanate reacts noncatalytically with myeloperoxidase-derived HOCl to produce hypothiocyanite (OSCN(-)), thereby potentially limiting the propensity of HOCl to inflict host tissue damage that can lead to inflammatory diseases. However, the efficiency with which SCN(-) captures HOCl in vivo depends on the concentration of SCN(-) relative to other chemical targets. In blood plasma, where the concentration of SCN(-) is relatively low, proteins may be the principal initial targets of HOCl, and chloramines are a significant product. Chloramines eventually decompose to irreversibly damage proteins. In the present study, we demonstrate that SCN(-) reacts efficiently with chloramines in small molecules, in proteins, and in Escherichia coli cells to give OSCN(-) and the parent amine. Remarkably, OSCN(-) reacts faster than SCN(-) with chloramines. These reactions of SCN(-) and OSCN(-) with chloramines may repair some of the damage that is inflicted on protein amines by HOCl. Our observations are further evidence for the importance of secondary reactions during the redox cascades that are associated with oxidative stress by hypohalous acids.

N-chlorotaurine, a natural antiseptic with outstanding tolerability

N-chlorotaurine, the N-chloro derivative of the amino acid taurine, is a long-lived oxidant produced by activated human granulocytes and monocytes. Supported by a high number of in vitro studies, it has mainly anti-inflammatory properties and seems to be involved in the termination of inflammation. The successful synthesis of the crystalline sodium salt (Cl-HN-CH(2)-CH(2)-SO(3)Na, NCT) facilitated its development as an endogenous antiseptic. NCT can be stored long-term at low temperatures, and it has killing activity against bacteria, fungi, viruses and parasites. Transfer of the active chlorine to amino groups of molecules of both the pathogens and the human body (transhalogenation) enhances rather than decreases its activity, mainly because of the formation of monochloramine. Furthermore, surface chlorination after sublethal incubation times in NCT leads to a post-antibiotic effect and loss of virulence of pathogens, as demonstrated for bacteria and yeasts. Being a mild oxidant, NCT proved to be very well tolerated by human tissue in Phase I and II clinical studies. A 1% aqueous solution can be applied to the eye, skin ulcerations, outer ear canal, nasal and paranasal sinuses, oral cavity and urinary bladder, and can probably be used for inhalation. Therapeutic efficacy in Phase II studies has been shown in external otitis, purulently coated crural ulcerations and keratoconjunctivitis, so far. Based upon all presently available data, NCT seems to be an antiseptic with a very good relation between tolerability and activity. Recently, C-methylated derivatives of NCT have been invented, which are of interest because of improved stability at room temperature.

Inorganic chemistry of defensive peroxidases in the human oral cavity

The innate host response system is comprised of various mechanisms for orchestrating host response to microbial infection of the oral cavity. The heterogeneity of the oral cavity and the associated microenvironments that are produced give rise to different chemistries that affect the innate defense system. One focus of this review is on how these spatial differences influence the two major defensive peroxidases of the oral cavity, salivary peroxidase (SPO) and myeloperoxidase (MPO). With hydrogen peroxide (H(2)O(2)) as an oxidant, the defensive peroxidases use inorganic ions to produce antimicrobials that are generally more effective than H(2)O(2) itself. The concentrations of the inorganic substrates are different in saliva vs. gingival crevicular fluid (GCF). Thus, in the supragingival regime, SPO and MPO work in unison for the exclusive production of hypothiocyanite (OSCN(-), a reactive inorganic species), which constantly bathes nascent plaques. In contrast, MPO is introduced to the GCF during inflammatory response, and in that environment it is capable of producing hypochlorite (OCl(-)), a chemically more powerful oxidant that is implicated in host tissue damage. A second focus of this review is on inter-person variation that may contribute to different peroxidase function. Many of these differences are attributed to dietary or smoking practices that alter the concentrations of relevant inorganic species in the oral cavity (e.g.: fluoride, F(-); cyanide, CN(-); cyanate, OCN(-); thiocyanate, SCN(-); and nitrate, NO(3)(-)). Because of the complexity of the host and microflora biology and the associated chemistry, it is difficult to establish the significance of the human peroxidase systems during the pathogenesis of oral diseases. The problem is particularly complex with respect to the gingival sulcus and periodontal pockets (where the very different defensive stratagems of GCF and saliva co-mingle). Despite this complexity, intriguing in vitro and in vivo studies are reviewed here that reveal the interplay between peroxidase function and associated inorganic chemistry.

Effect of N-chlorotaurine mouth rinses on plaque regrowth and plaque vitality

The purpose of this 4-day plaque regrowth study was to assess the effect of N-chlorotaurine (NCT) mouth rinses on plaque inhibition and plaque vitality. Eighty volunteers participated in this investigator-blind, randomized, clinical controlled study in parallel groups. No oral hygiene was permitted except rinsing with a 2% or 3% NCT mouth rinse, a positive or a negative control. Primary parameters were the plaque index (Silness and Löe, Acta Odontol Scand, 22:121-135, 1964) and plaque vitality (Netuschil et al., J Clin Periodontol, 16:484-488, 1989) after the final rinse. In addition, another plaque index (Turesky et al., J Periodontol, 41:41-43, 1970), plaque area, and bleeding on probing were recorded. All parameters were taken at baseline and day 5. U test was applied on a 5% error level. No differences in plaque inhibition were found between the two NCT formulations and the negative control. However, a statistically significant reduction of plaque vitality compared to the negative and positive control was observed. Discoloration of the tongue and unpleasant taste were recorded in participants in the NCT groups. NCT mouth rinses did not inhibit plaque regrowth, but they did reduce the vitality of plaque bacteria. Methods of prolonging the substantivity of the NCT mouth rinses should be investigated to enhance the antibacterial properties of these formulations.

Comparison of taurine chloramine and taurine bromamine effects on rheumatoid arthritis synoviocytes

Fibroblast-like synoviocytes (FLS) participate in rheumatoid arthritis (RA) chronic synovitis by producing pro-inflammatory cytokines (IL-6, IL-8), growth factors (VEGF) and other inflammatory mediators (PGE2, NO). We have previously reported that Tau-Cl, generated by neutrophils, inhibits in vitro some of these pathogenic RA FLS functions. Taurine bromamine (Tau-Br) originates from eosinophils and neutrophils, and its immunoregulatory activities are poorly known. Therefore, we investigated the effects of Tau-Br on RA FLS functions and compared it to Tau-Cl anti-inflammatory action. When applied at noncytotoxic concentrations: (i) Tau-Br inhibited IL-6 and PGE2 production with potency similar to Tau-Cl (IC50 approximately 250 microM), (ii) Tau-Br failed to affect VEGF and IL-8 synthesis, while Tau-Cl exerted inhibitory effect (IC50 approximately 400 microM), (iii) none of these compounds affected NO generation and iNOS expression. Thus, Tau-Cl is more effective than Tau-Br in normalization of pro-inflammatory RA FLS functions.