Taurine bromamine (TauBr)--its role in immunity and new perspectives for clinical use

Hypochlorous Acid Chemistry in Mammalian Cells—Influence on Infection and Role in Various Pathologies

This review discusses the formation of hypochlorous acid HOCl and the role of reactive chlorinated species (RCS), which are catalysed by the enzyme myeloperoxidase MPO, mainly located in leukocytes and which in turn contribute to cellular oxidative stress. The reactions of RCS with various organic molecules such as amines, amino acids, proteins, lipids, carbohydrates, nucleic acids, and DNA are described, and an attempt is made to explain the chemical mechanisms of the formation of the various chlorinated derivatives and the data available so far on the effects of MPO, RCS and halogenative stress. Their presence in numerous pathologies such as atherosclerosis, arthritis, neurological and renal diseases, diabetes, and obesity is reviewed and were found to be a feature of debilitating diseases.

Application of Metabolomics to the Discovery of Biomarkers for Ischemic Stroke in the Murine Model: a Comparison with the Clinical Results

Ischemic stroke (IS) is a major cause of mortality and disability worldwide. However, the pathogenesis of IS remains unknown, and methods for early prediction and diagnosis of IS are lacking. Metabolomics can be applied to biomarker discovery and mechanism exploration of IS by exploring metabolic alterations. In this review, 62 IS metabolomics studies in the murine model published from January 2006 to December 2020 in the PubMed and Web of Science databases were systematically reviewed. Twenty metabolites (e.g., lysine, phenylalanine, methionine, tryptophan, leucine, lactate, serine, N-acetyl-aspartic acid, and glutathione) were reported consistently in more than two-third murine studies. The disturbance of metabolic pathways, such as arginine biosynthesis; alanine, aspartate and glutamate metabolism; aminoacyl-tRNA biosynthesis; and citrate cycle, may be implicated in the development of IS by influencing the biological processes such as energy failure, oxidative stress, apoptosis, and glutamate toxicity. The transient middle cerebral artery occlusion model and permanent middle cerebral artery occlusion model exhibit both common and distinct metabolic patterns. Furthermore, five metabolites (proline, serine, LysoPC (16:0), uric acid, glutamate) in the blood sample and 7 metabolic pathways (e.g., alanine, aspartate, and glutamate metabolism) are shared in animal and clinical studies. The potential biomarkers and related pathways of IS in the murine model may facilitate the biomarker discovery for early diagnosis of IS and the development of novel therapeutic targets.

Taurine as a Natural Antioxidant: From Direct Antioxidant Effects to Protective Action in Various Toxicological Models

Natural antioxidants have received tremendous attention over the last 3 decades. At the same time, the attitude to free radicals is slowly changing, and their signalling role in adaptation to stress has recently received a lot of attention. Among many different antioxidants in the body, taurine (Tau), a sulphur-containing non-proteinogenic β-amino acid, is shown to have a special place as an important natural modulator of the antioxidant defence networks. Indeed, Tau is synthesised in most mammals and birds, and the Tau requirement is met by both synthesis and food/feed supply. From the analysis of recent data, it could be concluded that the direct antioxidant effect of Tau due to scavenging free radicals is limited and could be expected only in a few mammalian/avian tissues (e.g., heart and eye) with comparatively high (>15-20 mM) Tau concentrations. The stabilising effects of Tau on mitochondria, a prime site of free radical formation, are characterised and deserve more attention. Tau deficiency has been shown to compromise the electron transport chain in mitochondria and significantly increase free radical production. It seems likely that by maintaining the optimal Tau status of mitochondria, it is possible to control free radical production. Tau's antioxidant protective action is of great importance in various stress conditions in human life, and is related to commercial animal and poultry production. In various in vitro and in vivo toxicological models, Tau showed AO protective effects. The membrane-stabilizing effects, inhibiting effects on ROS-producing enzymes, as well as the indirect AO effects of Tau via redox balance maintenance associated with the modulation of various transcription factors (e.g., Nrf2 and NF-κB) and vitagenes could also contribute to its protective action in stress conditions, and thus deserve more attention.

The Anti-Inflammatory Effect of Taurine on Cardiovascular Disease

Taurine is a non-protein amino acid that is expressed in the majority of animal tissues. With its unique sulfonic acid makeup, taurine influences cellular functions, including osmoregulation, antioxidation, ion movement modulation, and conjugation of bile acids. Taurine exerts anti-inflammatory effects that improve diabetes and has shown benefits to the cardiovascular system, possibly by inhibition of the renin angiotensin system. The beneficial effects of taurine are reviewed.

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.

Successful treatment of a unique chronic multi-bacterial scalp infection with N-chlorotaurine, N-bromotaurine and bromamine T

Microbial species can act in synergy to circumvent environmental stress conditions and survive. In addition, biofilms are a serious public-health issue globally and constitute a clinical emergency. Infection persistence, increased morbidity and mortality, and antibiotic resistance are consequences of poly-microbial synergy. Due to inherited complexity and synergy between numerous species, newer antimicrobial agents of increased efficacy and tolerability are needed. In this unique medical case, a chronic (9 year) multi-bacterial scalp infection was differentially diagnosed from other inflammatory skin disorders by prolonged microbiological culture. The bacterial species found seem to have caused lesions of visible biofilm not documented previously in the medical literature. This complicated infection was treated successfully and rapidly with the combined topical application of the active halogen compounds N-chlorotaurine, N-bromotaurine and bromamine T, which is in contrast to the previous failed systemic and topical therapeutic approaches. This study strengthens the case for the use of active halogen compounds against multi-bacterial infections of the skin in the future, without the occurrence of resistance.

Combined Biological Effects of N-Bromotaurine Analogs and Ibuprofen. Part I: Influence on Inflammatory Properties of Macrophages

Taurine haloamines (N-chlorotaurine, N-bromotaurine) due to their strong antiseptic and anti-inflammatory properties are good candidates for topical application in treatment of skin inflammatory/infectious disorders. Recently, we have demonstrated that more stable N-bromotaurine analogs (N-dibromo-dimethyl taurine, N-monobromo-dimethyl taurine) and bromamine T show strong microbicidal and anti-inflammatory properties at concentrations well tolerated by human cells and tissue. Non-steroidal anti-inflammatory drugs (NSAIDs) with cyclooxygenase (COX) inhibitory activity are commonly used in various inflammatory diseases. However, systemic administration of NSAIDs may result in adverse side effects. For example, the use of ibuprofen in children with varicella is associated with enhanced serum levels of TNF-α and with increased risk of necrotizing soft tissue infections and secondary skin infections caused by invasive streptococci. The aim of this study was to examine combined immunomodulatory effects of bromamines and ibuprofen on J774.A1 macrophages. We have shown that the primary activity of ibuprofen, the inhibition of PGE2 production by activated macrophages was intensified in the presence of bromamines. Most importantly, the stimulatory effect of ibuprofen on production of inflammatory cytokines (TNF-α, IL-6) was inhibited by all tested bromamines. These observations indicate that bromamines may neutralize massive production of TNF-α at sites of inflammation, a side effect of ibuprofen. Therefore, we suggest that systemic administration of ibuprofen (NSAIDs) in treatment of inflammatory/infectious skin diseases should be supported by topical application of bromamines as an adjunctive therapy.

Combined Biological Effects of N-Bromotaurine Analogs and Ibuprofen. Part II: Influence on a Local Defense System

The stable N-bromotaurine analogs (N-dibromo-dimethyl taurine, N-monobromo-dimethyl taurine), and bromamine T (BAT) show anti-inflammatory and microbicidal properties. These bromamines are good candidates for a treatment of skin infectious/inflammatory diseases as local antiseptics. Ibuprofen, a non-steroidal anti-inflammatory drug (NSAID), is commonly used in various infectious/inflammatory diseases due to its analgesic and antipyretic therapeutic effects. However, systemic administration of ibuprofen may also result in adverse side effects. It has been reported that ibuprofen enhances serum levels of TNF-α and worsens secondary skin infections caused by invasive streptococci (S. pyogenes). Recently we have demonstrated that bromamines inhibit the stimulatory effect of ibuprofen on the production of inflammatory cytokines (TNF-α, IL-6). The aim of this study was to examine the combined antibacterial actions of ibuprofen and bromamines against S. pyogenes and their joint effect on the generation of reactive oxygen species (ROS) by activated neutrophils and macrophages. We have shown that the microbicidal activity of bromamines against S. pyogenes was not altered by ibuprofen. On the other hand, co-administration of ibuprofen and bromamines markedly decreased the generation of ROS by activated neutrophils and macrophages. Finally, we discuss how the antioxidant combined effect of bromamines and ibuprofen may affect a local defense system.

UPLC-QTOF/MS-Based Metabolomics Reveals the Protective Mechanism of Hydrogen on Mice with Ischemic Stroke

As a reductive gas, hydrogen plays an antioxidant role by selectively scavenging oxygen free radicals. It has been reported that hydrogen has protective effects against nerve damage caused by ischemia-reperfusion in stroke, but the specific mechanism is still unclear. Therefore, this study aims to investigate the protective effects of hydrogen on stroke-induced ischemia-reperfusion injury and its detailed mechanism. Two weeks after the inhalation of high concentrations (66.7%) of hydrogen, middle cerebral artery occlusion (MCAO) was induced in mice using the thread occlusion technique to establish an animal model of the focal cerebral ischemia-reperfusion. Then, a metabolomics analysis of mouse cerebral cortex tissues was first performed by ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF/MS) to study the metabolic changes and protective mechanisms of hydrogen on stroke ischemia-reperfusion injury. According to the metabolomic profiling of cortex tissues, 29 different endogenous metabolites were screened, including palmitoyl-L-carnitine, citric acid, glutathione, taurine, acetyl-L-carnitine, N-acetylaspartylglutamic acid (NAAG), L-aspartic acid, lysophosphatidylcholine (LysoPC) and lysophosphatidylethanolamine (LysoPE). Through pathway analysis, the metabolic pathways were concentrate on the glutathione pathway and the taurine pathway, mitochondrial energy metabolism and phospholipid metabolism that related to the oxidative stress process. This result reveals that hydrogen may protect against ischemic stroke by reducing oxidative stress during ischemia-reperfusion, thereby protecting nerve cells from reactive oxygen species(ROS).

Swift Cure of a Chronic Wound Infected With Multiresistant Staphylococcus aureus in an Elderly Patient With Stage 5 Renal Disease

We present a case of a 91-year-old female with stage 5 renal disease, diabetes type 2, and considerable weakness, suffering from a 2-month-old wound infected by a multiresistant Staphylococcus aureus. The wound measured 7 cm in length, 5 cm in width, and 1.5 cm in depth, having purulent white edges and exudates exceeding the size of the wound. The systemic antibiotic use was opposing to improve the patient's clinical condition due to underlying nephrotoxicity that may have deteriorated renal failure and resistance of the infecting pathogen. The halogenated taurine (Tau) derivatives N-chlorotaurine (NCT) and N-bromotaurine (NBrT) with potent anti-inflammatory and antimicrobial efficacy were alternatively employed as combination topical treatment to provide a therapeutic solution. Each agent was applied separately with an interval of 5 minutes as a 1% spray in aqueous solution every 30 minutes during the day for 3 days. This treatment was very well tolerated and led to rapid disappearance of the purulent exudate, rapid epithelialization, and complete healing. To avoid relapse, the application was continued 4 times daily for a further 4 days. No complications occurred in the course of treatment. This case report confirms the therapeutic efficacy of NCT in chronic purulent wounds. NBrT is well tolerated, too, and can be used in combination with NCT in emergency clinical settings. Its potential as a single agent should be investigated in further studies. Advancement of wound closure by these agents proved to be life-saving for this patient. Further molecular research is needed to identify mechanisms that promote wound healing.

Effect of Taurine on Thymus Differentiation of Dex-Induced Immunosuppressive Mice

Taurine (2-aminoethanesulfonic acid) has positive effects on the formation of immune systems. In this study, we evaluated the effects of taurine on the development of T lymphocyte subpopulations in thymus of immunosuppresive mice. The immunosuppressed mice model was established by intraperitoneal injection of dexamethasone (Dex) for 7 days. Mice (male, Kunming strain) were randomly divided into three groups, the normal control group (Cont.), the Dex-induced immunosuppressive model group (Dex + PBS), and the taurine intervention group (Dex + TAU). Taurine was administered at a dose of 200 mg/kg for 30 days or until euthanasia. Total cell numbers in the thymi of mice were evaluated by cell count, and the flow cytometry was used to determine the proportion of different cell subsets. Our results showed that the size and weight of thymi of Dex + PBS group were significantly smaller than those of Cont. group, and taurine administration efficiently increased the thymus index. Taurine also significantly increased the number of CD4- CD8- double negative (DN), CD4+ CD8+ double positive (DP), CD4+ single positive (CD4+) and CD8+ SP (CD8+) cells compared with the Dex + PBS group, but did not affect the CD4+/CD8+ cell ratio in thymus of Dex-induced immunoseppressive mice. Our results suggested that taurine has a positive effect on thymus differentiation in Dex-induced immunosuppressive mice.

Comparative Analysis of Microbicidal and Anti-inflammatory Properties of Novel Taurine Bromamine Derivatives and Bromamine T

Taurine, the most abundant free amino acid in leukocyte cytosol traps hypohalous acids (HOCl and HOBr) to produce N-chlorotaurine (taurine chloramine, NCT and N-bromotaurine (taurine bromamine, Tau-NHBr,) respectively. Both haloamines show anti-inflammatory and antimicrobial properties. However, the therapeutic applicability of Tau-NHBr is limited due to its relatively poor stability. To overcome this disadvantage, we have synthesized the stable N-bromotaurine compounds N-monobromo-2,2-dimethyltaurine (Br-612) and N-dibromo-2,2-dimethyltaurine (Br-422). The aim of this study was to compare anti-inflammatory and microbicidal properties of Br-612 and Br-422 with that of Tau-NHBr and bromamine T (BAT). We have shown that all the tested compounds show similar anti-inflammatory properties. Importantly, the stable N-bromotaurine compounds exerted even stronger microbicidal activity than Tau-NHBr. Finally, for the purpose of topical application of these compounds we have developed a carbomer-based bioadhesive solid dosage form of BAT and Br-612, featuring sustained release of the active substance.

Enzymatic and bactericidal activity of myeloperoxidase in conditions of halogenative stress

Myeloperoxidase (MPO), found mainly in neutrophils, is released in inflammation. MPO produces reactive halogen species (RHS), which are bactericidal agents. However, RHS overproduction, i.e., halogenative stress, can also damage host biomolecules, and MPO itself may be targeted by RHS. Therefore, we examined the susceptibility of MPO to inactivation by its primary products (HOCl, HOBr, HOSCN) and secondary products such as taurine monochloramine (TauCl) and taurine monobromamine (TauBr). MPO was dose-dependently inhibited up to complete inactivity by treatment with HOCl or HOBr. TauBr diminished the activity but did not eliminate it. TauCl had no effect. MPO became inactivated when producing HOCl or HOBr but not HOSCN. Taurine protected MPO against inactivation when MPO was catalyzing oxidation of Cl− to HOCl, whereas taurine failed to prevent inactivation when MPO was working with Br−, either alone or in combination with Cl−. SCN− interfered with HOCl-mediated MPO inhibition. UV–vis spectra showed that heme degradation is involved in HOCl- and HOBr-mediated MPO inactivation. A negative linear correlation between the remaining chlorinating activity of HOCl- or HOBr-modified MPO and Escherichia coli survival upon incubation with MPO/H2O2/Cl− was found. This study elucidated the possibility of MPO downregulation by MPO-derived RHS, which could counteract halogenative stress.

A review of diagnosis and treatment of acne in adult female patients

This review focuses on the treatment options for adult female patients with acne. Acne in adult female patients may start during adolescence and persist or have an onset in adulthood. Acne has various psychosocial effects that impact patients’ quality of life. Treatment of acne in adult women specifically has its challenges due to the considerations of patient preferences, pregnancy, and lactation. Treatments vary widely and treatment should be tailored specifically for each individual woman. We review conventional therapies with high levels of evidence, additional treatments with support from cohort studies and case reports, complementary and/or alternative therapies, and new agents under development for the treatment of patients with acne.

Treatment Modalities for Acne

Acne is a common inflammatory skin disease which affects the pilosebaceous units of the skin. It can have severe psychological effects and can leave the patient with severe skin scarring. There are four well-recognized pathological factors responsible for acne which is also the target for acne therapy. In this review, different treatment options are discussed, including topical (i.e., retinoids, and antibiotics) and systemic (i.e., retinoids, antibiotics, and hormonal) treatments. Since the general public has been showing an increasing interest in more natural and generally safer treatment options, the use of complementary and alternative medicines (CAM) for treating acne was also discussed. The use of physical therapies such as comedone extraction, cryoslush therapy, cryotherapy, electrocauterization, intralesional corticosteroids and optical treatments are also mentioned. Acne has been extensively researched with regards to the disease mechanism as well as treatment options. However, due to the increasing resistance of Propionibacterium acnes towards the available antibiotics, there is a need for new treatment methods. Additionally, the lack of necessary evidence on the efficacy of CAM therapies makes it necessary for researchers to investigate these treatment options further.

Superior bactericidal activity of N-bromine compounds compared to their N-chlorine analogues can be reversed under protein load

AIMS

To investigate and compare the bactericidal activity (BA) of active bromine and chlorine compounds in the absence and presence of protein load.

METHODS AND RESULTS

Quantitative killing tests against Escherichia coli and Staphylococcus aureus were performed both in the absence and in the presence of peptone with pairs of isosteric active chlorine and bromine compounds: hypochlorous and hypobromous acid (HOCl and HOBr), dichloro- and dibromoisocyanuric acid, chlorantine and bromantine (1,3-dibromo- and 1,3 dichloro-5,5-dimethylhydantoine), chloramine T and bromamine T (N-chloro- and N-bromo-4-methylbenzenesulphonamide sodium), and N-chloro- and N-bromotaurine sodium. To classify the bactericidal activities on a quantitative basis, an empirical coefficient named specific bactericidal activity (SBA), founded on the parameters of killing curves, was defined: SBA= mean log reductions/(mean exposure times x concentration) [mmol 1(-1) min (-1)]. In the absence of peptone, tests with washed micro-organisms revealed a throughout higher BA of bromine compounds with only slight differences between single substances. This was in contrast to chlorine compounds, whose killing times differed by a factor of more than four decimal powers. As a consequence, also the isosteric pairs showed according differences. In the presence of peptone, however, bromine compounds showed an increased loss of BA, which partly caused a reversal of efficacy within isosteric pairs.

CONCLUSIONS

In medical practice, weakly oxidizing active chlorine compounds like chloramines have the highest potential as topical anti-infectives in the presence of proteinaceous material (mucous membranes, open wounds). Active bromine compounds, on the other hand, have their chance at insensitive body regions with low organic matter, for example skin surfaces.

SIGNIFICANCE AND IMPACT OF THE STUDY

The expected protein load is one of the most important parameters for selection of a suited active halogen compound.

Exogenous taurine attenuates mitochondrial oxidative stress and endoplasmic reticulum stress in rat cardiomyocytes

Taurine, a conditionally essential amino acid, plays a critical role in cardiovascular function. Here we examined the effect of taurine on mitochondria and endoplasmic reticulum in rat cardiomyocytes during glucose deprivation (GD). Data showed that cell viability, intracellular taurine contents, and taurine transporter expression were decreased during GD. In contrast, an increase in reactive oxygen species and intracellular Ca(2+) contents was observed. GD also caused disrupted mitochondrial membrane potential, apoptotic cell death, and dissociation of unfolded protein response (UPR)-relative proteins in cardiomyocytes. Signal transduction analysis showed that Bcl-2 family protein balance was disturbed, caspase-12 was activated and UPR-relative protein levels were up-regulated. Moreover, pre-treatment with 80 mM exogenous taurine attenuated GD effect in cardiomyocytes. Our results suggest that taurine have beneficial effects on inhibiting mitochondria-dependent cell apoptosis and UPR-associated cell apoptosis and might have clinical implications on acute myocardial infarction in future.

Light emission from tryptophan oxidation by hypobromous acid

The emission of ultraweak light from cells is a phenomenon associated with the oxidation of biomolecules by reactive oxygen species. The indole moiety present in tryptophan, serotonin and melatonin is frequently associated with the emission of light during the oxidation of these metabolites. This study presents results for hypobromous acid (HOBr) oxidation of tryptophan as a putative endogenous source of ultraweak light emission. We found that chemiluminescence elicited by the oxidation of tryptophan by HOBr was significantly higher than by hypochlorous acid (HOCl). This difference was related to secondary oxidation reactions, which were more intense using HOBr. The products identified during oxidation by HOCl, but depleted by using HOBr, were N-formylkynurenine, kynurenine, 1,2,3,3a,8,8a-hexahydro-3a-hydroxypyrrolo[2,3-b]-indole-2-carboxylic acid, oxindolylalanine and dioxindolylalanine. The emission of light is dependent on the free α-amino group of tryptophan, and hence, the indole of serotonin and melatonin, although efficiently oxidized, did not produce chemiluminescence. The emission of light was even greater using taurine monobromamine and dibromamine as the oxidant compared to HOBr. A mechanism based on bromine radical intermediates is suggested for the higher efficiency in light emission. Altogether, the experimental evidence described in the present study indicates that the oxidation of free tryptophan or tryptophan residues in proteins is an important source of ultraweak cellular emission of light. This light emission is increased in the presence of taurine, an amino acid present in large amounts in leukocytes, where this putative source of ultraweak light emission is even more relevant.

Physiological roles of taurine in heart and muscle

Taurine (aminoethane sulfonic acid) is an ubiquitous compound, found in very high concentrations in heart and muscle. Although taurine is classified as an amino acid, it does not participate in peptide bond formation. Nonetheless, the amino group of taurine is involved in a number of important conjugation reactions as well as in the scavenging of hypochlorous acid. Because taurine is a fairly inert compound, it is an ideal modulator of basic processes, such as osmotic pressure, cation homeostasis, enzyme activity, receptor regulation, cell development and cell signalling. The present review discusses several physiological functions of taurine. First, the observation that taurine depletion leads to the development of a cardiomyopathy indicates a role for taurine in the maintenance of normal contractile function. Evidence is provided that this function of taurine is mediated by changes in the activity of key Ca²⁺ transporters and the modulation Ca²⁺ sensitivity of the myofibrils. Second, in some species, taurine is an established osmoregulator, however, in mammalian heart the osmoregulatory function of taurine has recently been questioned. Third, taurine functions as an indirect regulator of oxidative stress. Although this action of taurine has been widely discussed, its mechanism of action is unclear. A potential mechanism for the antioxidant activity of taurine is discussed. Fourth, taurine stabilizes membranes through direct interactions with phospholipids. However, its inhibition of the enzyme, phospholipid N-methyltransferase, alters the phosphatidylcholine and phosphatidylethanolamine content of membranes, which in turn affects the function of key proteins within the membrane. Finally, taurine serves as a modulator of protein kinases and phosphatases within the cardiomyocyte. The mechanism of this action has not been studied. Taurine is a chemically simple compound, but it has profound effects on cells. This has led to the suggestion that taurine is an essential or semi-essential nutrient for many mammals.