Immunologic consequences of taurine deficiency in cats

Taurine amino acid supplementation impacts performance, blood hematology, oxidative stress, and jejunum morphology in broiler chickens

Excess levels of free radicals cause oxidative damage to cells. Taurine is a rare amino acid with antioxidant effects whose dietary deficiency increases oxidative damage to the cell membrane. To investigate the effects of dietary taurine supplementation on performance, blood hematology, oxidative stress, and jejunum morphology in broilers, 300 broilers (Ras 308, 1D of age) were randomly allocated into 4 groups with 5 replicates of 15 birds. The experimental treatments included basic diet (control treatment) and basic diet with 1, 3, and 6 g/kg taurine amino acid. During 1 to 45 days, the inclusion of taurine supplementation in diets improved the body weight gain (BWG), feed consumption (FC), and feed conversion ratio (FCR) of broilers (P < 0.05). In CBC tests, the experimental treatments were significantly different concerning the red blood cell (RBC) count, the average hemoglobin in the cell, the RBC width in the curve, and the hematocrit (P < 0.05). Despite the significance of oxidative stress among the treatments, the control and fourth treatments showed the highest and the lowest oxidative stress, respectively (P < 0.05). Also, in jejunum morphology, the fourth treatment showed the best performance in terms of villus length and width and the villus length to crypt depth (V/C) ratio (P < 0.05). Overall, 6 g/kg taurine addition to the diet reduced oxidative stress and positive features in the jejunum morphology while improving the functional traits of broilers.

Taurine promotes B-cell activation by interaction with the VH /VL framework regions of B-cell receptor

Taurine (Tau) is a special sulphur-containing amino acid and has been widely used as a dietary supplement. Although Tau exists in lymphocytes in large quantities, the physiological significance of Tau to modulate human immunity is unknown. In the present study, we first found that Tau regulates the B-cell receptor (BCR)-mediated signal transduction and induces the B cells activation. The IgG production of mice after ovalbumin immunization was also increased by Tau administration. Moreover, the isothermal titration calorimetry and surface plasmon resonance analysis have shown that Tau specifically bound to the IgG2a-BCR. The Tau could bind to IgG F(ab')₂ regions via fluorescence spectroscopy analysis. In the molecular docking analysis, Tau bound to the framework regions (FRs) of variable region of the heavy chains (V_H ) and in the light chains (V_L ) of IgG2a-BCR. Our results suggested that Tau could improve the activation of B cells by interaction with the V_H /V_L FRs of BCR.

Versatile Triad Alliance: Bile Acid, Taurine and Microbiota

Taurine is the most abundant free amino acid in the body, and is mainly derived from the diet, but can also be produced endogenously from cysteine. It plays multiple essential roles in the body, including development, energy production, osmoregulation, prevention of oxidative stress, and inflammation. Taurine is also crucial as a molecule used to conjugate bile acids (BAs). In the gastrointestinal tract, BAs deconjugation by enteric bacteria results in high levels of unconjugated BAs and free taurine. Depending on conjugation status and other bacterial modifications, BAs constitute a pool of related but highly diverse molecules, each with different properties concerning solubility and toxicity, capacity to activate or inhibit receptors of BAs, and direct and indirect impact on microbiota and the host, whereas free taurine has a largely protective impact on the host, serves as a source of energy for microbiota, regulates bacterial colonization and defends from pathogens. Several remarkable examples of the interaction between taurine and gut microbiota have recently been described. This review will introduce the necessary background information and lay out the latest discoveries in the interaction of the co-reliant triad of BAs, taurine, and microbiota.

NMR-Based Metabolomics Identify Metabolic Change in Spleen of Idiopathic Thrombocytopenic Purpura Patients

Idiopathic thrombocytopenic purpura (ITP) is a common hematological disease and the abnormal platelet destruction in the spleen is a critical pathological mechanism for ITP. However, the metabolomic change in the spleen caused by ITP is still unclear. In the present study, the metabolomic information of 18 ITP and 20 normal spleen samples were detected by using ¹H high-resolution magic angle spinning NMR spectroscopy (¹H MAS NMR). Compared with normal spleen, the concentrations of acetate, alanine, glutamine, glycerol, isoleucine, lysine, valine, phenylalanine, leucine, and methanol in ITP spleen tissue were elevated and 3-hydroxybutyric acid, ascorbate, asparagine, ethanol, glycogen, low-density lipoprotein, malonate, myo-inositol, glycerophosphocholine, pyroglutamate, and taurine were decreased. Amino acids metabolic pathways, such as branched-chain amino acids pathway, were identified as the main involved pathways based on enrichment analysis. The decrease in taurine level in the spleen was the most obvious metabolic signature involving ITP with high sensitivity and specificity to distinguish the spleen of ITP from the normal (CI: 0.825–0.982). Notably, the level of taurine in the spleen was negatively correlated with the efficacy of splenectomy (r = 0.622, p = 0.006). Collectively, the data from our study revealed previously unknown ITP-related metabolomic changes in the spleen and found a potential diagnostic and efficacy-predictive biomarker for ITP treatment.

The Role of Taurine in Mitochondria Health: More Than Just an Antioxidant

Taurine is a naturally occurring sulfur-containing amino acid that is found abundantly in excitatory tissues, such as the heart, brain, retina and skeletal muscles. Taurine was first isolated in the 1800s, but not much was known about this molecule until the 1990s. In 1985, taurine was first approved as the treatment among heart failure patients in Japan. Accumulating studies have shown that taurine supplementation also protects against pathologies associated with mitochondrial defects, such as aging, mitochondrial diseases, metabolic syndrome, cancer, cardiovascular diseases and neurological disorders. In this review, we will provide a general overview on the mitochondria biology and the consequence of mitochondrial defects in pathologies. Then, we will discuss the antioxidant action of taurine, particularly in relation to the maintenance of mitochondria function. We will also describe several reported studies on the current use of taurine supplementation in several mitochondria-associated pathologies in humans.

Biomarker identification and pathway analysis of rheumatoid arthritis based on metabolomics in combination with ingenuity pathway analysis

Rheumatoid arthritis (RA) is a common autoimmune and inflammatory disease worldwide, but understanding its pathogenesis is still limited. In this study, plasma untargeted metabolomics of a discovery cohort and targeted analysis of a verification cohort were performed by gas chromatograph mass spectrometry (GC/MS). Univariate and multivariate statistical analysis were utilized to reveal differential metabolites, followed by the construction of biomarker panel through random forest (RF) algorithm. The pathways involved in RA were enriched by differential metabolites using Ingenuity Pathway Analysis (IPA) suite. Untargeted metabolomics revealed eighteen significantly altered metabolites in RA. Among these metabolites, a three-metabolite marker panel consisting of L-cysteine, citric acid and L-glutamine was constructed, using random forest algorithm that could predict RA with high accuracy, sensitivity and specificity based on a multivariate exploratory receiver operator characteristic (ROC) curve analysis. The panel was further validated by support vector machine (SVM) and partial least squares discriminant analysis (PLS-DA) algorithms, and also verified with targeted metabolomics using a verification cohort. Additionally, the dysregulated taurine biosynthesis pathway in RA was revealed by an integrated analysis of metabolomics and transcriptomics. Our findings in this study not only provided a mechanism underlying RA pathogenesis, but also offered alternative therapeutic targets for RA.

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.

Mild to moderate hyponatremia at discharge is associated with increased risk of recurrence in patients with community-acquired pneumonia

BACKGROUND

Hyponatremia is the most common electrolyte disorder in hospitalized patients with pneumonia. Different studies have shown an association of hyponatremia on admission and worse patient's outcome. Yet, the impact of hyponatremia at discharge or of hyponatremia correction on patient's prognosis is unknown.

METHODS

This is a preplanned secondary data analysis from a double-blind, randomized, placebo-controlled trial of hospitalized patients with community-acquired pneumonia and prednisone treatment. The primary outcome was the impact of hyponatremia on admission and at discharge on patient relevant outcomes (i.e. mortality, rehospitalization and recurrence rate) within 180 days.

RESULTS

Of the 708 included patients, 185 (26.1%) were hyponatremic on admission. Of these, 28 (15.1%) were still hyponatremic at discharge. 34 (4.8%) patients developed hyponatremia during hospitalization despite being normonatremic on admission. Patients with hyponatremia at discharge had a higher rate of pneumonia recurrence as compared to normonatremic patients (OR 2.68; 95%-CI 1.09-6.95; p = 0.037). Among patients with hyponatremia at discharge, patients who were already hyponatremic on admission showed the strongest association with increased recurrence rate (OR 4.01; 95%-CI 1.08-12.64; p = 0.022). In contrast, recurrence rate was not affected in patients who were hyponatremic on admission but had normalized serum sodium levels at discharge (p = 0.73).

CONCLUSION

Mild to moderate hyponatremia at discharge is associated with an increased risk of recurrence in hospitalized patients with pneumonia. This association is particularly strong for patients who are hyponatremic both on admission and at discharge, emphasizing the importance of hyponatremia correction during hospitalization.

Taurine administration prevents the intestine from the damage induced by beta-lactoglobulin sensitization in a murine model of food allergy

BACKGROUND

Allergy to cow's milk proteins has often been associated with dysfunction of the intestinal mucosa caused by chronic inflammation in infants. This study evaluated the protective effect of taurine on intestinal damage induced by beta-lactoglobulin (β-Lg) in Balb/c mice used as an animal model of allergy to cow's milk proteins.

METHODS

Balb/c mice were treated with taurine administered orally by gavage (3mmol/kg/day) or intraperitoneally (100mg/kg/day) for two weeks, then sensitized intraperitoneally with β-Lg. The electrophysiological parameters: active ion transport of chloride (Short-circuit current: Isc) and the passive ion permeability (Conductance: G) were measured ex vivo in Ussing chamber by intestine challenge with β-Lg. Histological study was used to assess gut inflammation. Serum levels of TNF-α and IL-6 were measured. Serum IgG and IgE anti-β-Lg were determined by ELISA.

RESULTS

Compared with sensitized mice, β-Lg challenge of intestinal epithelium of taurine-pre-treated mice in Ussing chamber did not influence the intensity of Isc, nor produce any changes in the G, reflecting a reduction in the secretory response and epithelial permeability. Histological and morphometric analysis showed that taurine reduced the intestinal damage and limited intestine retraction caused by β-Lg sensitization. No statistically significant difference in the serum levels of TNF-α or IL-6 was found after oral or intraperitoneal administration of taurine. Treatment with taurine significantly decreased the IgG (p<0.001) and IgE anti β-Lg levels (p<0.05).

CONCLUSIONS

These results have for the first time provided evidence that pre-treatment with taurine appears to prevent intestinal damage induced by β-Lg.

Effect of Taurine on Intestinal Microbiota and Immune Cells in Peyer's Patches of Immunosuppressive Mice

Taurine is a sulfur-containing amino acid which has strong activities in enhancing immunity. Gut microbiota is closely interrelated with intestinal mucosal immunity, but the effects and mechanisms of taurine on intestinal microbiota and mucosal immune cells under an immunosuppressive condition remain unclear. This study was conducted to investigate the effect of taurine on gut microbiota and immune cells in Peyer's patches (PPs) of dexamethasone (Dex)-induced immunosuppressive mice. Mice (4-week-old, Male) were randomly divided into three groups: the Control group (n = 12), the Dex-induced immunosuppressive model group (n = 12) and the taurine intervention group (n = 12). The model was established by Dex injection for 7 days and the taurine intervention group was gavaged 100 mg/kg soluble taurine for 30 days. The changes of intestinal microbiota and immune cells in PPs were tested by denaturing gradient gel electrophoresis (DGGE) and flow cytometry, respectively. Results showed that the microbiota in immunosuppressive mice was obvious different compared with control group, in which, the Lachnospiraceae and Ruminococcaceae groups were significantly reduced, and their reduction were reversed after taurine intervention. Compared to the control group, the total cell number in PPs, as well as the subsets of CD3⁺ cells (T cells), CD19⁺ cells (B cells) in model groups were significantly lower, and they were dramatically improved after taurine treatment. Our results suggested that taurine has a positive effect on i ntestinal homeostasis of the immunosuppressive mice.

Allostasis and the Clinical Manifestations of Mild to Moderate Chronic Hyponatremia: No Good Adaptation Goes Unpunished

When homeostatic regulatory systems are unable to maintain a normal serum sodium concentration, the organism must adapt to demands of a disordered internal environment, a process known as "allostasis." Human cells respond to osmotic stress created by an abnormal serum sodium level with the same adaptations used by invertebrate organisms that do not regulate body fluid osmolality. To avoid intolerable changes in their volume, cells export organic osmolytes when exposed to a low serum sodium concentration and accumulate these intracellular solutes when serum sodium concentration increases. The brain's adaptation to severe hyponatremia (serum sodium < 120 mEq/L) has been studied extensively. However, adaptive responses occur with less severe hyponatremia and other tissues are affected; the consequences of these adaptations are incompletely understood. Recent epidemiologic studies have shown that mild (sodium, 130-135 mEq/L) and moderate (sodium, 121-129 mEq/L) chronic hyponatremia, long thought to be inconsequential, is associated with adverse outcomes. Adaptations of the heart, bone, brain, and (possibly) immune system to sustained mild to moderate hyponatremia may adversely affect their function and potentially the organism's survival. This review explores what is known about the consequences of mild to moderate chronic hyponatremia and the potential benefits of treating this condition.

A Novel Cysteine Sulfinic Acid Decarboxylase Knock-Out Mouse: Immune Function (II)

Taurine deficient mice lacking cysteine sulfinic acid decarboxylase (CSAD KO) were developed for investigating the various physiological roles of taurine including the development of the brain and eye as well as immune function. Due to severe abnormalities of immune function in a taurine deficient cat, the immune function including adoptive and innate immunity in taurine-deficient mice have been studied. Previously we demonstrated that B cell function in CSAD KO was reduced in both females and males. However, T cell function was significantly reduced only in females. In this study, we have examined innate immunity using macrophage activation with LPS or/and IFN-γ and polymorphonuclear leukocytes (PMN) activation with phorbol myristate acetate (PMA). Pro- and anti-inflammatory cytokines including IL-6, TNF-α and IL-10 as well as nitric oxide (NO) were determined using ELISA and Griess reagent, respectively. Peritoneal macrophages were activated with 1 μg/mL of lipopolysaccharide (LPS) and/or 50 U/mL of IFN-γ. In addition, superoxide anion was measured using peritoneal PMN activated with PMA in the presence and absence of superoxide dismutase. Superoxide anion production in activated PMN from CSAD KO homozygotes (HO) was not significantly different from wild-type (WT) with and without 25 mM taurine. IL-10 and TNF-α production in both female and male CSAD KO were not significantly different. IL-6 and NO were significantly lower only in females as previously observed in Con A-activated cellular proliferation of splenocytes. Cytokine production with 10 mM of taurine was not different, indicating the reduction of NO and IL-6 in females may be due to the absence of the CSAD gene, not due to low taurine concentrations.These data indicate that some measures of innate immunity were altered in female CSAD mice.

Understanding taurine CNS activity using alternative zebrafish models

Taurine is a highly abundant "amino acid" in the brain. Despite the potential neuroactive role of taurine in vertebrates has long been recognized, the underlying molecular mechanisms related to its pleiotropic effects in the brain remain poorly understood. Due to the genetic tractability, rich behavioral repertoire, neurochemical conservation, and small size, the zebrafish (Danio rerio) has emerged as a powerful candidate for neuropsychopharmacology investigation and in vivo drug screening. Here, we summarize the main physiological roles of taurine in mammals, including neuromodulation, osmoregulation, membrane stabilization, and antioxidant action. In this context, we also highlight how zebrafish models of brain disorders may present interesting approaches to assess molecular mechanisms underlying positive effects of taurine in the brain. Finally, we outline recent advances in zebrafish drug screening that significantly improve neuropsychiatric translational researches and small molecule screens.

Whole-Blood Taurine Concentrations in Cats With Intestinal Disease

Background

Increased delivery of taurine‐conjugated bile acids to the distal bowel can lead to dysbiosis resulting in colitis in mouse models of inflammatory bowel disease. A similar situation also could occur in cats with intestinal disease and might therefore result in decreased whole‐body taurine concentration.

Hypothesis/Objectives

To determine whether whole‐blood taurine concentrations are decreased at the time of diagnosis in cats with intestinal disease and to correlate concentrations with clinical and laboratory variables.

Animals

Twenty‐one cats with chronic inflammatory enteropathy and 7 cats with intestinal neoplasia from the University of Bristol.

Methods

Cats that had undergone a thorough investigation consisting of a CBC, serum biochemistry, serum cobalamin and folate concentrations, transabdominal ultrasound examination and histopathology of intestinal biopsy specimens, as well as additional testing if indicated, were included. Whole‐blood from these cats collected at the time of histologic diagnosis and stored in ethylenediaminetetraacetic acid was retrospectively analyzed for taurine with an automated high‐performance liquid chromatography amino acid analyzer.

Results

Although whole‐blood taurine concentrations remained within the reference range, those cats with predominantly large intestinal clinical signs had significantly lower concentrations than did cats with small intestinal and mixed bowel clinical signs (P = 0.033) and this difference also was significant when assessed only in cats with chronic inflammatory enteropathy (P = 0.019).

Conclusions and Clinical Importance

Additional studies are needed to determine whether large intestinal signs in cats with chronic inflammatory enteropathy are caused by alterations in the microbiota arising as a consequence of increased delivery of taurine‐conjugated bile acids.

Novel protective role of curcumin and taurine combination against experimental hepatocarcinogenesis

Hepatocarcinogenesis is a prerequisite to hepatocellular carcinoma (HCC), which is one of the most common cancers among humans. Therefore, it is important to search for agents that protect against hepatocarcinogenesis. The present study aimed to investigate the protective effects of a combination of taurine and curcumin against experimental hepatocarcinogenesis induced by diethyl nitrosamine (DENA) in a rat model. A total of 100 rats were divided into eight groups. Eight weeks following DENA injection and treatment with curcumin and taurine, the rats were sacrificed to obtain blood and hepatic tissue samples for the evaluation of various markers and histopathological observations. Serum levels of interleukin-2 (IL-2), interferon-γ (IFN-γ), α-fetoprotein (AFP) and α-L-fucosidase (AFU) were determined. Rats injected with DENA for eight weeks showed a high percentage of malignant changes in hepatic tissues, as well as a significant increases in the serum levels of AFP and AFU and significant reductions in the serum levels of IL-2 and IFN-γ. Treatment with curcumin and taurine markedly reduced the extent of malignant changes in the rat liver tissues, with their liver tissues showing patterns similar to that of the normal control rats. In addition, this combination resulted in normal serum levels of IL-2, IFN-γ, AFP and AFU. The results of the present study suggested that a combination of curcumin and taurine may be a novel prophylactic agent against hepatocarcinogenesis in high-risk groups exposed to chemical hepatocarcinogens.

Immunotoxicity of skin acid secretion produced by the sea slug Berthellina citrina in mice spleen: Histological and Immunohistochemical study

Acid secretion containing sulfuric and hydrochloric acids is a fascinating defensive phenomenon within many groups of marine organisms. This study aimed to investigate the mice spleen histology and immunotoxicity using skin acid secretion (SAS) of the sea slug Berthellina citrina after oral administration. The spleen showed atrophy in the white pulp, decrease in the splenocytes density, megakaryocytes cytoplasmic degeneration as well as inflammatory cells infiltrations. The white and red pulp splenocytes number decreased time-dependently in the treated spleens. Additionally, the size of the megakaryocytes increased as compared with the control. The administration with SAS increased the number of the IgA(+) cells aggregation in the splenic red pulp. Furthermore, after 7days of the administration, large number of dispersed IgA(+) cells were distributed in splenic parenchyma. The IgA(+) cells numbers increased time-dependently as compared with those in the control. The aggregation sizes and number of the F4/80(+) cell in the splenic red pulp were increased. Furthermore the F4/80(+) cells numbers increased time-dependently as compared with those in the control. The UEAI(+) cells were found as free cells but not in aggregations in the control splenic red pulp. Contradictory to the number of IgA(+) cells and F4/80(+) cells the number of the UEAI(+) cells decreased time-dependently after administration with SAS. Hematologically, abnormal numbers of WBCs different cells were observed after administration with SAS. This study provides new insight about the toxicity of a marine extract may be used in natural products industry or medical applications.

Comparative Analysis of Amino Acids, Nucleosides, and Nucleobases in Thais clavigera from Different Distribution Regions by Using Hydrophilic Interaction Ultra-Performance Liquid Chromatography Coupled with Triple Quadrupole Tandem Mass Spectrometry

Thais clavigera, as function food, is distributed widely along the coasts of China. To compare and tap its potentially nutritional and functional values, hydrophilic interaction ultra-performance liquid chromatography coupled with triplequadrupole tandem mass spectrometry (HILIC-UPLC-TQ-MS/MS) was used for simultaneous identification and quantification of amino acids, nucleosides, and nucleobases in the extracts of T. clavigera from 19 sea areas in China, and a PCA was further performed for comparing their content variation in different distribution regions. The total contents of amino acids varied from 116.74 mg/g to 298.58 mg/g being higher than contents of nucleosides and nucleobases that varied from 2.65 mg/g and 20.49 mg/g. Among the habitats, Hainan province had content advantages on others. By PCA, samples collected from different regions were classified into three groups. For specific constituents, lysine accounted for large part of essential amino acids; glycine and taurine also play important roles in the delicate taste and health care function of it. Inosine takes up most of total contents of nucleosides and nucleobases. These results provided good data for establishing quality standard of T. clavigera related products and their further development and utilization.

The ubiquitin-proteasome system and autophagy are defective in the taurine-deficient heart

Taurine depletion leads to impaired mitochondrial function, as characterized by reduced ATP production and elevated superoxide generation. These defects can fundamentally alter cardiomyocyte function and if left unchanged can result in cell death. To protect against these stresses, cardiomyocytes possess quality control processes, such as the ubiquitin-proteasome system (UPS) and autophagy, which can rejuvenate cells through the degradation of damaged proteins and organelles. Hence, the present study tested the hypothesis that reactive oxygen species generated by damaged mitochondria initiates UPS and autophagy in the taurine-deficient heart. Using transgenic mice lacking the taurine transporter (TauTKO) as a model of taurine deficiency, it was shown that the levels of ubiquitinated protein were elevated, an effect associated with a decrease in ATP-dependent 26S β5 proteasome activity. Treating the TauTKO mouse with the mitochondria-specific antioxidant, mitoTEMPO, largely abolished the increase in ubiquitinated protein content. The TauTKO heart was also associated with impaired autophagy, characterized by an increase in the initiator, Beclin-1, and autophagosome content, but a defect in the generation of active autophagolysosomes. Although mitoTEMPO treatment only restores the oxidative balance within the mitochondria, it appeared to completely disrupt the crosstalk between the damaged mitochondria and the quality control processes. Thus, mitochondrial oxidative stress is the main trigger initiating the quality control systems in the taurine-deficient heart. We conclude that the activation of the UPS and autophagy is another fundamental function of mitochondria.

Effect of taurine and potential interactions with caffeine on cardiovascular function

The major impetus behind the rise in energy drink popularity among adults is their ability to heighten mental alertness, improve physical performance and supply energy. However, accompanying the exponential growth in energy drink usage have been recent case reports and analyses from the National Poison Data System, raising questions regarding the safety of energy drinks. Most of the safety concerns have centered on the effect of energy drinks on cardiovascular and central nervous system function. Although the effects of caffeine excess have been widely studied, little information is available on potential interactions between the other active ingredients of energy drinks and caffeine. One of the active ingredients often mentioned as a candidate for interactions with caffeine is the beta-amino acid, taurine. Although taurine is considered a conditionally essential nutrient for humans and is thought to play a key role in several human diseases, clinical studies evaluating the effects of taurine are limited. However, based on this review regarding possible interactions between caffeine and taurine, we conclude that taurine should neutralize several untoward effects of caffeine excess. In agreement with this conclusion, the European Union's Scientific Committee on Food published a report in March 2003 summarizing its investigation into potential interactions of the ingredients in energy drinks. At the cardiovascular level, they concluded that "if there are any interactions between caffeine and taurine, taurine might reduce the cardiovascular effects of caffeine." Although these interactions remain to be further examined in humans, the physiological functions of taurine appear to be inconsistent with the adverse cardiovascular symptoms associated with excessive consumption of caffeine-taurine containing beverages.

Development of a novel cysteine sulfinic Acid decarboxylase knockout mouse: dietary taurine reduces neonatal mortality

We engineered a CSAD KO mouse to investigate the physiological roles of taurine. The disruption of the CSAD gene was verified by Southern, Northern, and Western blotting. HPLC indicated an 83% decrease of taurine concentration in the plasma of CSAD^−/−. Although CSAD^−/− generation (G)1 and G2 survived, offspring from G2 CSAD^−/− had low brain and liver taurine concentrations and most died within 24 hrs of birth. Taurine concentrations in G3 CSAD^−/− born from G2 CSAD^−/− treated with taurine in the drinking water were restored and survival rates of G3 CSAD^−/− increased from 15% to 92%. The mRNA expression of CDO, ADO, and TauT was not different in CSAD^−/− compared to WT and CSAD mRNA was not expressed in CSAD^−/−. Expression of Gpx 1 and 3 was increased significantly in CSAD^−/− and restored to normal levels with taurine supplementation. Lactoferrin and the prolactin receptor were significantly decreased in CSAD^−/−. The prolactin receptor was restored with taurine supplementation. These data indicated that CSAD KO is a good model for studying the effects of taurine deficiency and its treatment with taurine supplementation.

Taurine induces proliferation of neural stem cells and synapse development in the developing mouse brain

Taurine is a sulfur-containing amino acid present in high concentrations in mammalian tissues. It has been implicated in several processes involving brain development and neurotransmission. However, the role of taurine in hippocampal neurogenesis during brain development is still unknown. Here we show that taurine regulates neural progenitor cell (NPC) proliferation in the dentate gyrus of the developing brain as well as in cultured early postnatal (P5) hippocampal progenitor cells and hippocampal slices derived from P5 mice brains. Taurine increased cell proliferation without having a significant effect on neural differentiation both in cultured P5 NPCs as well as cultured hippocampal slices and in vivo. Expression level analysis of synaptic proteins revealed that taurine increases the expression of Synapsin 1 and PSD 95. We also found that taurine stimulates the phosphorylation of ERK1/2 indicating a possible role of the ERK pathway in mediating the changes that we observed, especially in proliferation. Taken together, our results demonstrate a role for taurine in neural stem/progenitor cell proliferation in developing brain and suggest the involvement of the ERK1/2 pathways in mediating these actions. Our study also shows that taurine influences the levels of proteins associated with synapse development. This is the first evidence showing the effect of taurine on early postnatal neuronal development using a combination of in vitro, ex-vivo and in vivo systems.

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.

Effective T-cell recall responses require the taurine transporter Taut

T-cell activation and the subsequent transformation of activated T cells into T-cell blasts require profound changes in cell volume. However, the impact of cell volume regulation for T-cell immunology has not been characterized. Here we studied the role of the cell-volume regulating osmolyte transporter Taut for T-cell activation in Taut-deficient mice. T-cell mediated recall responses were severely impaired in taut(-/-) mice as shown with B16 melanoma rejection and hapten-induced contact hypersensitivity. CD4(+) and CD8(+) T cells were unequivocally located within peripheral lymph nodes of unprimed taut(-/-) mice but significantly decreased in taut(-/-) compared with taut(+/+) mice following in vivo activation. Further analysis revealed that Taut is critical for rescuing T cells from activation-induced cell death in vitro and in vivo as shown with TCR, superantigen, and antigen-specific activation. Consequently, reduction of CD4(+) and CD8(+) T cells in taut(-/-) mice upon antigen challenge resulted in impaired in vivo generation of T-cell memory. These findings disclose for the first time that volume regulation in T cells is an element in the regulation of adaptive immune responses and that the osmolyte transporter Taut is crucial for T-cell survival and T-cell mediated immune reactions.

Taurine: energy drink for T cells

The activation of T cells causes many cellular changes, including alterations in cell morphology, motility, and size. While all immunologists know that T cells increase their size and become "blasted" upon activation, little attention has been paid to the question of how cell size is regulated and how this process influences T-cell responses. In this issue of the European Journal of Immunology, Kaesler et al. [Eur. J. Immunol. 2012. 42: 831-841] demonstrate that the organic osmolyte taurine and its transporter Taut are instrumental in driving cell-volume regulation and therefore the T-cell response. In the absence of Taut, effector and memory T-cell responses in mice are severely impaired, mainly due to increased apoptosis of effector cells. Hence, this paper provides an important link between the regulation of cell size and effector T-cell responses.

Taurine plays an important role in the protection of spermatogonia from oxidative stress

It has been demonstrated that taurine has various physiological functions in the body. We demonstrated that taurine is abundant in the serum, liver, muscle and testis of the Japanese eel (Anguilla japonica). In the eel testis, taurine is found mainly in spermatogonia and is weakly expressed also in the Sertoli cells. We have further found in the eel testis that taurine is actively accumulated via the sodium/chloride-dependent taurine transporter (TauT; SLC6A6), which is expressed in germ cells. In our current study, the effects of taurine on the anti-oxidant response were examined. Taurine was found to promote the total superoxide dismutase (SOD) activity in the testis. Moreover, our results indicate that taurine does not affect the mRNA levels of copper-zinc (Cu/Zn) SOD or manganese SOD, but promotes the translation of Cu/Zn SOD. Overall, our present data suggest that taurine may modulate Cu/Zn SOD at the translational level and thereby may play an important role in the protection of germ cells from oxidative stress.

Sequencing and comparative genomic analysis of 1227 Felis catus cDNA sequences enriched for developmental, clinical and nutritional phenotypes

Background

The feline genome is valuable to the veterinary and model organism genomics communities because the cat is an obligate carnivore and a model for endangered felids. The initial public release of the Felis catus genome assembly provided a framework for investigating the genomic basis of feline biology. However, the entire set of protein coding genes has not been elucidated.

Results

We identified and characterized 1227 protein coding feline sequences, of which 913 map to public sequences and 314 are novel. These sequences have been deposited into NCBI's genbank database and complement public genomic resources by providing additional protein coding sequences that fill in some of the gaps in the feline genome assembly. Through functional and comparative genomic analyses, we gained an understanding of the role of these sequences in feline development, nutrition and health. Specifically, we identified 104 orthologs of human genes associated with Mendelian disorders. We detected negative selection within sequences with gene ontology annotations associated with intracellular trafficking, cytoskeleton and muscle functions. We detected relatively less negative selection on protein sequences encoding extracellular networks, apoptotic pathways and mitochondrial gene ontology annotations. Additionally, we characterized feline cDNA sequences that have mouse orthologs associated with clinical, nutritional and developmental phenotypes. Together, this analysis provides an overview of the value of our cDNA sequences and enhances our understanding of how the feline genome is similar to, and different from other mammalian genomes.

Conclusions

The cDNA sequences reported here expand existing feline genomic resources by providing high-quality sequences annotated with comparative genomic information providing functional, clinical, nutritional and orthologous gene information.

Taurine and proliferation of lymphocytes in physically restrained rats

Background

Taurine is present in lymphocytes and seems to modulate certain immune cell functions. Among the effects of taurine on these cells are protection against antioxidants and regulation of inflammatory aspects of the immune response. Stress affects antigen presentation, traffic and proliferation of leukocytes, as well as antibody and cytokine secretion. The purposes of this study were to explore the possible direct effects of taurine concentrations on lymphoproliferation and interleukins levels in control and in physical restrained rats.

Methods

Lymphocytes of male Sprague-Dawley rats, stressed by physical restrain and controls (5 h per day for 5 days) were isolated from blood by Histopaque (1077 g/l) and differential adhesion to plastic, and then cultured (72 h) in the presence of different concentrations of taurine (0.5 – 50 mM), β-alanine (0.5 – 50 mM), or both, without or with the T cells mitogen, concanavalin A. Plasma and lymphocytes levels of pro-inflammatory interleukin-1β and anti-inflammatory interleukin-10 were respectively measured by Pierce Endogen rat ELISA Kits. Taurine in plasma and in lymphocytes were determined by HPLC.

Results

Lymphoproliferation of resting cells significantly decreased in the presence of 3 and 6 mM taurine and increased up to control level at 12 mM taurine. In concanavalin A-activated lymphocytes, the effect of taurine was greater. β-alanine increased lymphoproliferation in a bell shaped dose-dependent manner and decreased it in activated lymphocytes but in a lower magnitude. In combination, β-alanine impaired the effect of taurine at 3 and 6 mM. After restriction, no change in lymphoproliferation was observed at different concentrations of the amino acids without or with concanavalin A, although pro-inflammatory interleukin and taurine in plasma and in lymphocytes significantly increased.

Conclusions

Taurine affects lymphoproliferation in control rats, following a dose-dependent manner, an effect that might involve its transport into the cells. Elevation of interleukin-1β produced in stressed rats by physical restrain could seriously affect the immune balance, whereas taurine increase might be protective. These results suggest that taurine and taurine transport play a role in lymphoproliferation. In addition, modifications of taurine system in lymphocytes take place during restriction stress.

Effects of dietary taurine supplementation on growth performance and immune status in growing Japanese quail (Coturnix coturnix japonica)

The effect of dietary taurine was investigated on performance and immune responses in growing (1 to 42 d) Japanese quail. One-day-old quails of both sexes (300) were randomly allotted to 12 groups with 25 quails in each group (3 dietary treatments, 4 replicates). They were fed with maize-soybean meal-based diets containing 0, 0.01, or 0.05% taurine for 42 d. Dietary 0.01% taurine decreased food intake (P < 0.05) in the starter phase but did not affect BW gain and feed efficiency from d 1 to 42 of age. In the starter phase, dietary 0.05% taurine did not affect food intake but increased weight gain and improved feed efficiency (P < 0.05). In the grower phase, dietary 0.05% taurine did not affect weight gain but improved feed efficiency and decreased food intake (P < 0.05). In the overall period, dietary 0.05% taurine improved feed efficiency and decreased food intake (P < 0.05). The relative weights of thymus were greater in the quails given 0.01% taurine in diet (P < 0.05). The relative weights of the bursa of Fabricius and thymus were greater in dietary 0.05% taurine compared with the control (P < 0.05).The quail serum anti-Newcastle disease virus hemagglutination antibody titer in the taurine-supplemented diet had no significant effects compared with the control (P > 0.05). The response to phytohemagglutinin measured as the foot web index was significantly increased by 0.05% taurine supplementation (P < 0.05). It is concluded that the taurine-supplemented diet has a beneficial effect on immune responses and performance in growing Japanese quail.

Taurine transporter in lymphocytes of patients with major depression treated with venlafaxine plus psychotherapy

The taurine transporter and taurine are present in lymphocytes, where taurine functions as an antioxidant and an anti-inflammatory agent. Taurine levels are elevated in lymphocytes of subjects with major depression, but returns to control levels after treatment with the antidepressant mirtazapine. Patients (40) were diagnosed using the Diagnostic and Statistical Manual IV of the American Psychiatric Association, and the severity of their condition was determined by the Hamilton Scale of Depression. One group of patients was treated with venlafaxine and the other with venlafaxine plus Neuro-Linguistic Programming. Lymphocytes were isolated from the peripheral blood by Ficoll/Hypaque. The coexistence of the taurine transporter with a subpopulation of CD4+ and CD8+ lymphocytes was measured by immunofluorescence. The levels of the pro-inflammatory, IL-2, and the anti-inflammatory, IL-4, cytokines were determined by ELISA while plasma amino acid levels were determined by HPLC. The percentage of CD4+ cells significantly decreased after both treatments, whereas the levels of CD8+ cells remained unchanged. The taurine transporter of CD4+ and CD8+ cells decreased after integrate treatment. No differences were found in the levels of IL-2 while IL-4 levels increased after integrate treatment. The observed effects of treatment on the taurine transporter and IL-4 content might modify lymphocyte activity during depression.

Which mechanisms are involved in taurine-dependent granulocytic immune response or amino- and α-keto acid homeostasis?

We examined the effects of beta-alanine (taurine analogue and taurine transport antagonist), taurine (regarding its role in neutrophil (PMN) immunonutrition) and taurine combined either with L-NAME (inhibitor of *NO-synthase), SNAP (*NO donor), DON (glutamine-analogue and inhibitor of glutamine-requiring enzymes), DFMO (inhibitor of ornithine-decarboxylase) and beta-alanine on neutrophil amino- and alpha-keto acid profiles or important PMN immune functions in order to establish whether taurine transport-, nitric oxide-, glutamine- or ornithine-dependent mechanisms are involved in any of the taurine-induced effects. According to the present findings, the taurine-mediated effect appears to be based primarily on a modulation of important transmembraneous transport mechanisms and only secondarily on directly or indirectly induced modifications in intragranulocytic amino- and alpha-keto acid homoeostasis or metabolism. Although a direct relation to the parallel observed immunological modifications can only be presumed, these results show very clearly that compositional modifications in the free intragranulocytic amino- and alpha keto-acid pools coinciding with changes in intragranulocytic taurine levels are relevant metabolic determinants that can significantly influence the magnitude and quality of the granulocytic immune response.

Is Taurine A Biomarker?

Taurine, a sulfur-containing amino acid present in high concentrations in mammals, plays an important role in several essential biological processes. Taurine is not incorporated into protein and is the most abundant free amino acid in the heart, retina, skeletal muscle, brain, and leukocytes. The ideal biomarker or biological measure should be reliable, reproducible, noninvasive, simple to perform, and inexpensive. Samples for biological measures should be easily obtained from physiological fluids such as blood or urine. Taurine levels in physiologic fluids have been useful for both diagnosing pathology and establishing a disease modifying therapy. In the specific case of taurine, it is important that patient information include nutritional supplementation as well as information on disease status and medications. Taurine has been measured in biological fluids due to the importance of this simple amino acid and its relative ease of determination. Taurine has been measured in animal models of disease as well as a variety of human conditions. However, it remains unclear how taurine should be used as a biomarker and in which situations this measurement would be a good prognostic or diagnostic indicator.

Taurine-Responsive Genes Related to Signal Transduction as Identified by cDNA Microarray Analyses of HepG2 Cells

Taurine-induced changes in the expression profiles of HepG2 cells were assessed using a cDNA microarray technology, and confirmed by real-time reverse transcription-polymerase chain reaction (RT-PCR) analyses. Of 8,298 human genes on the microarray, 128 genes (87 known genes) were up-regulated, and 349 (206 known genes) were down-regulated more than 2.0-fold by taurine. Among the 293 known genes regulated by taurine, a total of 44 genes were involved in signal transduction; 16 genes were up-regulated greater than 2.0-fold, and 28 genes were down-regulated more than 2.0-fold by taurine. The results of RT-PCR analyses for the five genes selected were consistent with our microarray data, although the fold changes in the expression level differed somewhat between the two analytical methods. Among signal transduction-related genes affected by taurine, four genes--mitogen-activated protein kinase (MAPK) kinase kinase 7, p21-activated kinase 4, sprouty homolog 2, and MAPK kinase 1--are implicated in the MAPK signaling pathway. Taurine also regulated the expression of signal transducer and activator of transcription (STAT) 3 gene involved in the Janus kinase-STAT pathway, and diacylglycerol kinase, zeta 104 kDa, the downstream mediator of the protein kinase C transmembrane signaling pathway. In conclusion, gene expression profiling of HepG2 cells treated with taurine provided us with new insights into the novel aspects of taurine as a possible regulator of MAPK signaling cascades and protein kinase C signaling pathways involved in cellular processes such as cell growth, differentiation, and apoptosis.

Alterations in neutrophil (PMN) free intracellular alpha-keto acid profiles and immune functions induced by L-alanyl-L-glutamine, arginine or taurine

The objective of this study was to determine the dose as well as duration of exposure-dependent effects of L-alanyl-L-glutamine, arginine or taurine on polymorphonuclear neutrophil (PMN) free alpha-keto acid profiles and, in a parallel study, on PMN immune functions. Exogenous L-alanyl-L-glutamine significantly increased PMN alpha-ketoglutarate, pyruvate PMN superoxide anion (O2-) generation, hydrogen peroxide (H2O2) formation and released myeloperoxidase (MPO) activity. Arginine also led to significant increases in alpha-ketoglutarate, pyruvate, MPO release and H2O2 generation. Formation of O2- on the other hand was decreased by arginine. Incubation with taurine resulted in lower intracellular pyruvate and alpha-ketobutyrate levels, decreased O2- and H2O2 formation and a concomitant significantly increased MPO activity. We therefore believe that considerable changes in PMN free-alpha-keto-acid profiles, induced for example by L-alanyl-L-glutamine, arginine or taurine, may be one of the determinants in cell nutrition that considerably modulates the immunological competence of PMN.

Animal models of idiosyncratic drug reactions

Idiosyncratic drug reactions represent a major problem. In most cases the mechanisms of these reactions are unknown, but circumstantial evidence points to the involvement of reactive metabolites and the characteristics of the reactions suggest involvement of the immune system. If progress is to be made in dealing with these adverse reactions it is essential that we have a better understanding of their mechanisms, and it is hard to imagine testing mechanistic hypotheses without good animal models. Unfortunately, idiosyncratic reactions are also idiosyncratic in animals so few good models exist. The best models, in which a rodent develops a clinical syndrome similar to that which occurs in humans, appear to be penicillamine-induced autoimmunity in Brown Norway rats and nevirapine-induced skin rash in rats. Sulfamethoxazole-induced hypersensitivity in dogs and propylthiouracil-induced autoimmunity in cats are also similar to adverse reactions that occur in people, but they have practical limitations. Halothane-induced liver toxicity in guinea pigs and amodiaquine-induced bone marrow and liver toxicity in rats represent models in which there is an immune response and mild, reversible toxicity. It is possible that the development of immune tolerance is what limits the toxicity in these models, and if this is true, interventions that prevent tolerance might lead to good models. Although the history of developing animal models of idiosyncratic drug reactions is mostly one of failure, such models are essential. A better understanding of immune tolerance may greatly facilitate the development of better models; transgenic technology may also provide an important tool.

Taurine supplement in early life altered islet morphology, decreased insulitis and delayed the onset of diabetes in non-obese diabetic mice

AIMS/HYPOTHESIS

We hypothesised that nutritional taurine, which is important for the development of the endocrine pancreas and reduces cytokine-induced apoptosis in pancreatic beta cells, would prevent or delay the onset of autoimmune diabetes, if given early in life to the non-obese diabetic (NOD) mouse.

METHODS

Pregnant NOD mice received a diet supplemented with taurine throughout gestation or until weaning, and the pancreas of the offspring was examined using immunohistochemistry. This was done at postnatal day 14 and after 8 weeks (assessment of insulitis). The animals were also monitored until they became diabetic.

RESULTS

At 14 days, pancreatic islet mass was significantly greater in animals treated with taurine than in controls. This finding was associated with a greater incidence of islet cell proliferation and a lower incidence of apoptosis. At age 8 weeks the number of islets manifesting insulitis was reduced by more than half, and the area of insulitis was reduced by 90%. Taurine treatment delayed the mean onset time of diabetes from 18 to 30 weeks in females, and from 30 to 38 weeks in males, while 20% of treated females remained free of diabetes after one year.

CONCLUSIONS/INTERPRETATION

Taurine supplementation in early life altered islet development, reduced insulitis and delayed the onset of diabetes in NOD mice.

Traditional and nontraditional effective and noneffective therapies for cardiac disease in dogs and cats

In this article, I presented my (admittedly biased) perspective of the current state of knowledge addressing the role of traditional and non-traditional therapeutics. The focus has been on the nontraditional therapeutics. Among these, the only ones I currently consider to have any documented value are taurine and, less commonly, L-carnitine. The role of taurine (and likely carnitine) remains limited to cases of documented deficiency. In the case of cats with taurine deficiency-induced myocardial failure, it is now clear that most cases are the result of formulation errors by owners and manufacturers. In dogs, it is less clear if the causes of taurine deficiencies represent manifestations of pathologic conditions or dietary formulations errors. Increasingly, it seems the latter may prove to be the case in most, if not all, circumstances. Finally, I would like to reiterate the conclusions of the last time I addressed this topic (with coauthors Kittleson and Sanderson) in this publication. Remember that there is limited evidence to support the therapeutic recommendations you read or hear in most circumstances. The urge to do "something" for patients can be overwhelmingly attractive. Nevertheless, whether it is administration of drugs or prescribing nutraceuticals or prescription diets, strongly consider the source of the information urging you to prescribe, the strength of the evidence presented, the financial costs to the owner, and the potential risks and benefits to the patient.

Taurine: new implications for an old amino acid

Taurine is a semi-essential amino acid and is not incorporated into proteins. In mammalian tissues, taurine is ubiquitous and is the most abundant free amino acid in the heart, retina, skeletal muscle, brain, and leukocytes. In fact, taurine reaches up to 50 mM concentration in leukocytes. Taurine has been shown to be tissue-protective in many models of oxidant-induced injury. One possibility is that taurine reacts with hypochlorous acid, produced by the myeloperoxidase pathway, to produce the more stable but less toxic taurine chloramine (Tau-Cl). However, data from several laboratories demonstrate that Tau-Cl is a powerful regulator of inflammation. Specifically, Tau-Cl has been shown to down-regulate the production of pro-inflammatory mediators in both rodent and human leukocytes. Taurolidine, a derivative of taurine, is commonly used in Europe as an adjunctive therapy for various infections as well as for tumor therapy. Recent molecular studies on the function of taurine provide evidence that taurine is a constituent of biologic macromolecules. Specifically, two novel taurine-containing modified uridines have been found in both human and bovine mitochondria. Studies investigating the mechanism of action of Tau-Cl have shown that it inhibits the activation of NF-kappaB, a potent signal transducer for inflammatory cytokines, by oxidation of IkappaB-alpha at Met45. Key enzymes for taurine biosynthesis have recently been cloned. Cysteine sulfinic acid decarboxylase, a rate-limiting enzyme for taurine biosynthesis, has been cloned and sequenced in the mouse, rat and human. Another key enzyme for cysteine metabolism, cysteine dioxygenase (CDO), has also been cloned from rat liver. CDO has a critical role in determining the flux of cysteine between cysteine catabolism/taurine synthesis and glutathione synthesis. Taurine transporter knockout mice show reduced taurine, reduced fertility, and loss of vision due to severe apoptotic retinal degeneration. Apoptosis induced by amino chloramines is a current and important finding since oxidants derived from leukocytes play a key role in killing pathogens. The fundamental importance of taurine in adaptive and acquired immunity will be unveiled using genetic manipulation.

Effects of propofol and taurine on intracellular free amino acid profiles and immune function markers in neutrophils in vitro

We have examined the effects of propofol, taurine, and the combination of propofol and taurine on amino acid profiles and the immune function markers superoxide anion (O2-), hydrogen peroxide (H2O2), and released myeloperoxidase (MPO) activity in neutrophils (PMN). Propofol led to significant changes in the dynamic PMN-free amino acid pool. Exogenous taurine significantly reduced PMN neutral amino acid and alpha-aminobutyrate (alpha-aba) as intracellular taurine increased. Incubation with propofol plus taurine resulted in lower intracellular taurine levels and elevated alpha-aba and neutral amino acid concentrations compared to propofol alone. Concerning PMN immune function markers, propofol significantly decreased O2- and H2O2 formation and released MPO. Taurine led to an increased release of MPO and concomitant significantly reduced O2- and H2O2 levels. When propofol and taurine were applied together they appeared to act additively with regard to superoxide and hydrogen peroxide formation. In the case of MPO, taurine neutralized propofol's effects, supporting the idea that MPO activity may be regulated by taurine. We believe therefore that taurine is important for strengthening PMN host defense capability, although the mechanisms are not yet clear. Moreover, taurine appears to act primarily by altering the PMN osmotic balance, while propofol seems to affect PMN amino acid metabolism and/or uptake and release.