"Activation" of alveolar leukocytes isolated from cats fed taurine-free diets

Large-Scale Analysis of Pollen Viability and Oxidative Level Using H2DCFDA-Staining Coupled with Flow Cytometry

Determining pollen viability and other physiological parameters is of critical importance for evaluating the reproductive capacity of plants, both for fundamental and applied sciences. Flow cytometry is a powerful high-performance high-throughput tool for analyzing large populations of cells that has been in restricted use in plant cell research and in pollen-related studies, it has been minimized mostly for determination of DNA content. Recently, we developed a flow cytometry-based approach for robust and rapid evaluation of pollen viability that utilizes the reactive oxygen species (ROS) fluorescent reporter dye H₂DCFDA (Luria et al., Plant J 98(5):942-952, 2019). This new approach revealed that pollen from Arabidopsis thaliana and Solanum lycopersicum naturally distribute into two subpopulations with different ROS levels. This method can be employed for a myriad of pollen-related studies, primarily in response to stimuli such as biotic or abiotic stress. In this chapter, we describe the protocol for H₂DCFDA staining coupled with flow cytometry analysis providing specific guidelines. These guidelines are broadly applicable to many other types of cellular reporters to further develop this novel approach in the field of pollen biology.

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.

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.

The antioxidant, taurine reduced lipopolysaccharide (LPS)-induced generation of ROS, and activation of MAPKs and Bax in cultured pneumocytes

Lipopolysaccharide (LPS) can cause damage to the epithelia of the respiratory tract. However, taurine can protect the lung tissue from such oxidant-induced inflammation. This study examined the effects of a LPS treatment on the intracellular calcium levels ([Ca(2+)]i) as well as the specific mechanisms of LPS-induced cell death in pneumocytes. In addition, the effects of taurine on the LPS-induced increase in the accumulation of reactive oxygen species (ROS) in pneumocytes were investigated. The [Ca(2+)]i in cultured pneumocytes was determined using microfluorescence techniques. The level of activation of the mitogen-activated protein kinases (MAPKs) and Bax protein were measured by Western blotting. LPS at 10 and 100 ng/ml induced cell death and decreased the viability of MRC-5 cells. Moreover, the intracellular Ca(2+) and ROS levels were increased by LPS. The LPS treatment led to the phosphorylation of ERK1/2, JNK and the activation of Bax. A pretreatment with 20 mM taurine reduced the LPS-induced production of ROS and MARK activity. These results show that a LPS treatment induces cell death in MRC-5 cells by increasing the intracellular ROS and Ca(2+) levels. The increase in the intracellular level of ROS promotes MAPKs activation and Bax translocation. Overall, LPS induces lung cell death by activating MAPKs. Furthermore, taurine decreased the LPS-induced generation of ROS and activation of MAPK and Bax.

Nutritional considerations for animals with pulmonary disease

Recent publications in the human and veterinary literature have indicated that patients with pulmonary disease require specific nutritional consideration to ensure that optimal benefit is derived with nutrition support. Although additional research is needed in this area, preliminary recommendations can be made using information from the scant studies performed thus far in veterinary medicine and from information extrapolated from the human literature. These recommendations are likely to provide significant clinical benefit to patients with pulmonary disease. This article aims to provide the reader with a summary of the available information and links to other relevant sources.

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.

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.

Age-related retinal degeneration in animal models of aging: possible involvement of taurine deficiency and oxidative stress

There is strong evidence that the retina degenerates with age. Electroretinogram deficits and photoreceptor cell death and structural abnormalities have been observed in both animal and human studies of aging. The mechanism behind this phenomenon is a very interesting area for scientific and medical study. Current data support the link between retinal degeneration and increased oxidative stress. Taurine is a free amino acid found in high millimolar concentrations in the retina, and age-related deficiency in retinal levels of taurine may contribute to the retinal degeneration associated with age. Taurine acts as an antioxidant and taurine replenishment is known to alleviate oxidative stress in the retina. Thus taurine supplementation may be useful in the treatment of age-related retinal dysfunction.

Chemiluminescence of pulmonary macrophages from patients with inactive sarcoidosis, in different radiological stages

Luminol-amplified chemiluminescence was generated by alveolar macrophages, harvested from the bronchoalveolar lavages of 16 patients with different radiological stages of non-invasive (asymptomatic) sarcoidosis. None of the patients received any steroid therapy during this study. The mean duration of the disease in these patients was 8 months, with a duration time range of 6-14 months. Six patients were in radiological stage 1, five in radiological stage 2 and five in radiological stage 3. Alveolar macrophages from bronchoalveolar lavages of eight healthy non-smoking volunteers were used as controls. All alveolar macrophages were stimulated by phorbol myristate acetate. A significant decrease was recorded in the intensity of chemiluminescence generated by the phorbol-ester-stimulated alveolar macrophages obtained from patients with sarcoidosis of radiological stages 1 and 2, as compared to the cells collected from healthy individuals (controls). No decrease was recorded in the chemiluminescence generated by stimulated alveolar macrophages collected from patients with radiological stage 3, or from unstimulated alveolar macrophages of any patient. These results provide us with an indicative tool, which might enable us to differentiate, on a functional basis, between the activities of alveolar macrophages in non-active sarcoidosis.

Effects of taurine on pulmonary responses to antigen in sensitized Brown-Norway rats

Oxidative stress appears relevant to asthma. Therefore, the effects of the antioxidant taurine (oral, 1 and 3 mmol x kg(-1) x day(-1) for 7 days before challenge) were examined on antigen-induced responses in sensitized Brown-Norway rats. Taurine did not reduce the bronchospasm produced by aerosol antigen but prevented airway hyperreactivity to 5-hydroxytryptamine (5-HT) at 24 h after antigen exposure, and reduced the eosinophils (from 0.178+/-0.038x10(6) to 0.044+/-0.014x10(6)* and 0.048+/-0.013x10(6)* cells ml(-1) in antigen and antigen+taurine 1 or 3 mmol x kg(-1), respectively; *P<0.05 vs. antigen), lipid hydroperoxides, and Evans blue dye extravasation in bronchoalveolar lavage fluid. Taurine levels in bronchoalveolar lavage fluid from antigen-challenged rats were higher than control values but treatment with taurine failed to further increase these levels. In conclusion, oral taurine showed beneficial effects in an in vivo model of experimental asthma, which confirm and extend the previous positive findings obtained in other models of lung injury.

Effects of etomidate on free intracellular amino acid concentrations in polymorphonuclear leucocytes in vitro

BACKGROUND

Previous studies have shown the inhibitory effects of etomidate on polymorphonuclear leucocyte (PMN) function. No reports exist, however, regarding free intracellular amino acid metabolism, although physiological cell metabolism and basic cell functions rely upon a balanced intracellular amino acid content and the cell membrane-mediated separation of cellular amino acids from the extracellular plasma amino acid pool. Thus, in the current study, we evaluated the effects of etomidate on free intracellular amino acid metabolism in PMN.

METHODS

With ethics committee approval, blood was withdrawn from 35 healthy volunteers and incubated (1 h) either with 0 microg/ml, 0.0156 microg/ml, 0.0625 microg/ml or 0.5 microg/ml of etomidate as well as with its additives (propylene glycol and Lipofundin MCT 10%). The PMN were separated using standardized Percoll-gradient and centrifugation procedure before deep-freezing and lyophilization techniques were employed. All PMN samples were dissolved in methanol/H2O, and the concentrations of free intracellular amino acids were monitored using both novel advanced PMN-separation and high-performance liquid chromatography techniques.

RESULTS

Etomidate influenced important free amino acid profiles in PMN in a dose-dependent manner, indicating complex changes of cellular amino acid turnover. Neither propylene glycol nor Lipofundin MCT 10% changed free amino acid concentrations in PMN.

CONCLUSIONS

For the first time, the effects of etomidate on free intracellular amino acid metabolism in PMN have been investigated. Our results draw attention to the biochemical pathways which may be involved in etomidate-induced alterations in PMN function and cellular immunocompetence.

Effects of in vivo taurine depletion on induced-chemiluminescence production in macrophages isolated from rat lungs

Alveolar macrophages isolated by pulmonary lavage from partially taurine-depleted rats demonstrated increased (2-2.6 fold) chemiluminescence due to the extracellular reaction between exogenous zymosan and various reactive forms of oxygen compared to macrophages isolated from control animals. Partial taurine depletion was achieved by adding 3% beta-alanine to the drinking water of the rats for 5 weeks prior to harvesting the macrophages. Superoxide dismutase activity was not increased in the lung tissue of the taurine-depleted rats. These data suggest that taurine has antioxidant properties and that taurine depletion is potentially deleterious to alveolar macrophages and pulmonary tissue.

Host defense--a role for the amino acid taurine?

Taurine (2-aminoethane sulphonic acid), a ubiquitous beta-amino acid is conditionally essential in man. It is not utilized in protein synthesis but found free or in some simple peptides. Derived from methionine and cysteine metabolism, taurine is known to play a pivotal role in numerous physiological functions. Some of the roles with which taurine has been associated include osmoregulation, antioxidation, detoxification and stimulation of glycolysis and glycogenesis. Intracellular taurine is maintained at high concentrations in a variety of cell types and alteration of cell taurine levels is difficult. The role of taurine within the cell appears to be determined by the cell type. Recent research has determined a regulatory role for taurinechloramine, the product formed by the reaction between taurine and neutrophil derived hypochlorous acid on macrophage function. Plasma taurine levels are also high, although decreases are observed in response to surgical injury and numerous pathological conditions including cancer and sepsis. Supplementary taurine replenishes decreased plasma taurine. Although commonly used as a dietary supplement in the Far East, the potential advantages of dietary taurine supplementation have not as yet been fully recognized in the Western World; this is an area which could prove to be beneficial in the clinical arena.

Antibodies to myeloperoxidase in propylthiouracil-induced autoimmune disease in the cat

Cats are known to develop a lupus-like syndrome similar to that observed in humans when treated with propylthiouracil. We have previously demonstrated that propylthiouracil and other drugs associated with lupus are oxidized in the presence of myeloperoxidase to reactive intermediates. We postulated that these reactive metabolites could modify myeloperoxidase resulting in anti-myeloperoxidase antibodies and possibly be responsible for the lupus-like syndrome. Five cats were treated with propylthiouracil and 2 developed the lupus-like syndrome as well as anti-myeloperoxidase antibodies. These appeared to correlate better with disease than antinuclear antibodies. The antibodies were true autoantibodies because the myeloperoxidase used to detect the antibodies did not require treatment with propylthiouracil. In a subsequent study in which the cat food contained a higher level of taurine, none of the animals developed the autoimmune syndrome. It is possible that diet also plays an important role in the development of such adverse reactions.