Taurine attenuates CD3/interleukin-2-induced T cell apoptosis in an in vitro model of activation-induced cell death (AICD)

Integrative analysis identified two subtypes and a taurine-related signature to predict the prognosis and efficacy of immunotherapy in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent subtypes of primary liver cancer, with high mortality and poor prognosis. Immunotherapy has revolutionized treatment strategies for many cancers. However, only a subset of patients with HCC achieve satisfactory benefits from immunotherapy. Therefore, a reliable biomarker that could predict the prognosis and immunotherapy response in patients with HCC is urgently needed. Taurine plays an important role in many physiological processes. However, its participation in the occurrence and progression of liver cancer and regulation of the composition and function of various components of the immune microenvironment remains elusive. In this study, we identified and validated two heterogeneous subtypes of HCC with different taurine metabolic profiles, presenting distinct genomic features, clinicopathological characteristics, and immune landscapes, using multiple bulk transcriptome datasets. Subsequently, we constructed a risk model based on genes related to taurine metabolism to assess the prognosis, immune cell infiltration, immunotherapy response, and drug sensitivity of patients with HCC. The risk model was validated using several independent external cohorts and showed a robust predictive performance. In addition, we evaluated the expression patterns of taurine metabolism-related genes in the tumor microenvironment and the heterogeneity of taurine metabolism among cancer cells using a single-cell transcriptome. In conclusion, our study provides insights into the important role played by taurine metabolism in tumor progression and immune regulation. Furthermore, the risk model can serve as a biomarker to assess patient prognosis and immunotherapy response, potentially helping clinicians make more precise and personalized clinical decisions.

Possible Mechanisms of Lymphopenia in Severe Tuberculosis

Tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium tuberculosis (M. tuberculosis). In lymphopenia, T cells are typically characterized by progressive loss and a decrease in their count results. Lymphopenia can hinder immune responses and lead to systemic immunosuppression, which is strongly associated with mortality. Lymphopenia is a significant immunological abnormality in the majority of patients with severe and advanced TB, and its severity is linked to disease outcomes. However, the underlying mechanism remains unclear. Currently, the research on the pathogenesis of lymphopenia during M. tuberculosis infection mainly focuses on how it affects lymphocyte production, survival, or tissue redistribution. This includes impairing hematopoiesis, inhibiting T-cell proliferation, and inducing lymphocyte apoptosis. In this study, we have compiled the latest research on the possible mechanisms that may cause lymphopenia during M. tuberculosis infection. Lymphopenia may have serious consequences in severe TB patients. Additionally, we discuss in detail potential intervention strategies to prevent lymphopenia, which could help understand TB immunopathogenesis and achieve the goal of preventing and treating severe TB.

Taurine enhances the antitumor efficacy of PD-1 antibody by boosting CD8+ T cell function

The functional state of CD8⁺ T cells determines the therapeutic efficacy of PD-1 blockade antibodies in tumors. Amino acids are key nutrients for maintaining T cell antitumor immunity. In this study, we used samples from lung cancer patients treated with PD-1 blockade antibodies to assay the amino acids in their serum by mass spectrometry. We found that lung cancer patients with high serum taurine levels generally responded to PD-1 blockade antibody therapy, in parallel with the secretion of high levels of cytotoxic cytokines (IFN-γ and TNF-α). CD8⁺ T cells cultured with exogenous taurine exhibited decreased apoptosis, enhanced proliferation, and increased secretion of cytotoxic cytokines. High SLC6A6 expression in CD8⁺ T cells was positively associated with an effector T cell signature. SLC6A6 knockdown limited the function and proliferation of CD8⁺ T cells. RNA sequencing revealed that SLC6A6 knockdown altered the calcium signaling pathway, oxidative phosphorylation, and T cell receptor signaling in CD8⁺ T cells. Furthermore, taurine enhanced T cell proliferation and function in vitro by stimulation of PLCγ1-mediated calcium and MAPK signaling. Taurine plus immune checkpoint blockade antibody significantly attenuated tumor growth and markedly improved the function and proliferation of CD8⁺ T cells in a mouse tumor model. Thus, our findings indicate that taurine is an important driver for improving CD8⁺ T cell immune responses and could serve as a potential therapeutic agent for cancer patients.

Taurine induces upregulation of p53 and Beclin1 and has antitumor effect in human nasopharyngeal carcinoma cells in vitro and in vivo

Taurine is an amino acid that has several physiological functions. Previously, we reported the apoptosis-inducing effect of taurine in human nasopharyngeal carcinoma (NPC) cells in vitro. However, the effect of taurine on NPC cell growth in vivo has not been elucidated. Autophagy plays an important role in cell metabolism and exhibits antitumor effects under certain conditions. In this study, we investigated the effects of taurine on apoptosis- and autophagy-related molecules in NPC cells in vitro and in vivo. In our in vitro study, NPC cells (HK1-EBV) were treated with taurine, and Western blot and immunocytochemical analyses revealed that taurine co-upregulated Beclin 1 and p53, with autophagy upregulation. In the in vivo study, we used a nude mouse model with subcutaneous xenografts of HK1-EBV cells. Once the tumors reached 2-3 mm in diameter, the mice were provided with distilled water (control group) or taurine dissolved in distilled water (taurine-treated group) ad libitum (day 1) and sacrificed on day 13. The volume and weight of the tumors were significantly lower in the taurine-treated group. Using immunohistochemistry (IHC), we confirmed that taurine treatment reduced the distinct cancer nest areas. IHC analyses also revealed that taurine promoted apoptosis, as evidenced by an increase in cleaved caspase-3, accompanied by upregulation of p53. Additionally, taurine increased LC3B and Beclin 1 expression, which are typical autophagy markers. The present study demonstrated taurine-mediated tumor growth suppression. Therefore, taurine may be a novel preventive strategy for NPC.

A Novel Overall Survival Prediction Signature Based on Comprehensive Research in Prostate Cancer Bone Metastases

BACKGROUND

Prostate adenocarcinoma (PRAD)-related bone metastases are a leading source of morbidity and mortality; however, good diagnostic biomarkers are not known yet. The aim of this study was to identify biomarkers and prognostic indicators for the diagnosis and treatment of PRAD-associated bone metastases.

METHODS

By combining the data from The Cancer Genome Atlas(TCGA) and PRAD SU2C 2019, We performed a comprehensive analysis of the expression differences, biological functions, and interactions of genes associated with PRAD bone metastasis. Annotation, visualization, and integrated discovery were accomplished through the use of gene ontology enrichment and gene set enrichment analysis. The protein-protein interaction network was constructed using the STRING database, and the diagnostic value of prognostic genes was validated using receiver-operating-characteristic and Kaplan-Meier curves.

RESULTS

Six genes (DDX47, PRL17, AS3MT, KLRK1, ISLR, and S100A8) associated with PRAD bone metastases were identified; these had prognostic value as well. Among them, enrichment was observed for the biological processes extracellular matrix tissue, extracellular structural tissue, steroid hormone response, and cell oxidative detoxification. KEGG analysis revealed enrichment in interactions with extracellular matrix receptors, diseases including Parkinson's disease and dilated cardiomyopathy, and estrogen signaling pathways. The area under the curve values of 0.8938, 0.9885, and 0.979, obtained from time-dependent receiver-operating-characteristic curve analysis for 1, 3, and 5-year overall survival confirmed the good performance of the model under consideration. S100A8 expression was not detected in the normal prostate tissue but was detected in PRAD.

CONCLUSIONS

We identified ISLR as a potential biomarker for PRAD bone metastasis. Moreover, the genes identified to have prognostic value may act as therapeutic targets for PRAD bone metastasis.

Taurine alleviates endoplasmic reticulum stress, inflammatory cytokine expression and mitochondrial oxidative stress induced by high glucose in the muscle cells of olive flounder (Paralichthysolivaceus)

The aim of the present study was to evaluate the effects of taurine on endoplasmic reticulum stress, inflammatory cytokine expression and mitochondrial oxidative stress induced by high glucose in primary cultured muscle cells of olive flounder (Paralichthys olivaceus). Three experimental groups were designed as follows: muscle cells of olive flounder incubated with three kinds of medium containing 5 mM glucose (control), 33 mM glucose (HG) or 33 mM glucose + 10 mM taurine (HG + T), respectively. Results showed that taurine addition significantly alleviated the decreased activity of superoxide dismutase (SOD) and the ratio of reduced to oxidized glutathione (GSH/GSSG) induced by high glucose. The increase of cellular reactive oxygen species (ROS), malondialdehyde content and cell apoptosis induced by high glucose were alleviated by taurine. Besides, gene expression of glucose-regulated protein 78, PKR-like ER kinase, tumor necrosis factor-α, interleukin-6, interleukin-1β, interleukin-8, muscle atrophy F-box protein and muscle RING-finger protein 1 were significantly up-regulated in the HG group, and taurine addition decreased the expression of these genes. High glucose led to the swelling of the endoplasmic reticulum (ER). Meanwhile, the nuclear translocation of nuclear factor κB (NF-κB) and the release of cytochrome C from mitochondria induced by high glucose were suppressed by taurine addition. These results demonstrated that taurine alleviated ERS, inflammation and mitochondrial oxidative stress induced by high glucose in olive flounder muscle cells. The ROS production, NF-κB signaling pathway and mitochondria function were the main targets of the biological effects of taurine under high glucose condition.

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.

Chlamydia muridarum infection induces CD4+ T cells apoptosis via PI3K/AKT signal pathway

Apoptosis is essential for the homeostatic control of the lymphocytes number during the development of an immune response to an invasive microorganism. CD4+ T cells play a major role in homeostasis of the immune system and are sufficient to confer protection against Chlamydia muridarum (Cm) infection in mice. The present study demonstrated that phosphatidylinositol 3-kinase (PI3K) p110δ mRNA and phosphorylation of protein kinase B (p-AKT) level were significantly increased in lung cells and spleen cells at day 3 and day 7 post-infection, p-AKT level was inhibited when adding PI3K inhibitor LY294002. Moreover, Cm infection induced high levels of IL-2/IL-2Rα in CD4+ T cells, which may relate to PI3K/AKT signal pathway activation. We observed that Cm infection significantly induced apoptosis of CD4+ T cells. The related apoptosis proteins Bcl-2 and Mcl-1 uneven expression levels were induced in CD4+ T cells by Cm infection. These findings provided in vivo and in vitro evidence that Cm infection induces CD4+ T cells apoptosis possibly via PI3K/AKT signal pathway.

Sorafenib- Taurine Combination Model for Hepatocellular Carcinoma Cells: Immunological Aspects

Sorafenib (Sor) is a multi-kinase inhibitor. It is recommended for the treatment of advanced hepatocellular carcinoma (HCC). However, Sor has severe and marked side effects. On the other hand, taurine (Tau) has been shown to enhance the therapeutic effects of cancer chemotherapy and also to enhance the function of leukocytes.

Here, we aimed to investigate the enhancing efficacy of Sor as well as minimizing its marked side effects by using Tau in combination in an immunological aspect. We evaluated the influence of Sor and Tau combination on the expression pattern of FOXP3 gene in HepG2 cells compared to peripheral blood mononuclear leukocytes (PBMCs) as control normal cells. Also, the levels of TGF-β and IL-10 released in culture media of both cells were determined. Our results revealed that, Tau reduced cytotoxicity of Sor on PBMC indicated by lactic dehyrogenase (LDH) release assay. In addition, Sor-Tau combination led to FOXP3 down-regulation in hepatic cancer cells (HepG2). The results showed also that, TGF-β levels decreased significantly in their culture media. In contrary, the cytokine increased in PBMCs culture media. Moreover, IL-10 was significantly elevated in the culture media of both cells. This study could open new avenues for the improvement of therapeutic efficacy of Sorafenib treated HCC patients by using Tau in combination.

Taurine Ameliorates High Glucose Induced Apoptosis in HT-22 Cells

Diabetes causes memory loss. Hippocampus is responsible for memory and increased apoptosis was found in diabetes patients. Taurine improved memory in diabetes condition. However, mechanism is unclear. In current study, hippocampal cell line HT-22 cells were subjected to analysis as five groups i.e. Control, High glucose (HG) at concentration of 150 mM, HG + 10 mM (T1), 20 mM (T2) and 40 mM (T3) taurine solution. TUNEL assay showed that HG increased the number of apoptotic cell significantly while taurine reduced apoptosis. Taurine increased phosphorylation of Akt in HT-22 cell treated with HG, and increased phosphorylation of Bad (p-Bad) was seen suggesting involvement of Akt/Bad signaling pathway. Expression of Bcl-2 was reduced in HG group but taurine improved this. Bax expression showed opposite trend. This indicated that taurine may reduce apoptosis by controlling balance of Bcl-2 and Bax. When the activation of Akt was blocked by using of perifosine, the effect of taurine disappears either partially or altogether. Thus, it was clear that taurine reduces apoptosis via Akt/Bad pathway in HT-22 cells exposed to HG which further improves downstream balance of Bcl-2 and Bax. This mechanism may be involved in apoptosis of hippocampus cells in diabetic condition.

Effect of Radiation on the Expression of Taurine Transporter in the Intestine of Mouse

There has been a growing interest on the effects of radiation since the Fukushima nuclear power plant accident of 2011. Taurine has been reported to have a radioprotective effect in irradiated mice. However, the detailed mechanism of this radioprotective effect is still awaiting clarification. The aim of this study was to investigation how radiation affects the expression of taurine and to shed light on the mechanism accounting for radioprotective and radiation mitigating effect. Six-week-old male mice were randomly divided into two groups: IR group (7 Gy irradiation) and IR + Tau group (7 Gy irradiation + taurine 3000 mg/kg/day). We examined the survival rate, the expression of taurine and taurine transporter in the small intestine and the urinary taurine concentration. In this study, no statistically significant difference was found in the survival rate between IR Group and IR + Tau Group. Three days and 7 days after irradiation, the urinary taurine concentration of IR + Tau group increased more than that of IR group. Three days and 10 days after irradiation, the expression of taurine and taurine transporter in the small intestine of IR group and IR + Tau group decreased more than that of normal small intestine. It is reported that radiation exposure increases the urinary taurine concentration. We found that the radiation exposure decreases the expression of the taurine transporter in the small intestine of mouse. This finding suggests that a decrease in the expression of the taurine transporter promotes the release of taurine from the tissue into the urine.

The impaired immune function and structural integrity by dietary iron deficiency or excess in gill of fish after infection with Flavobacterium columnare: Regulation of NF-κB, TOR, JNK, p38MAPK, Nrf2 and MLCK signalling

The aim of this study was to investigate the effects and potential mechanisms of dietary iron on immune function and structural integrity in gill of young grass carp (Ctenopharyngodon idella). A total of 630 grass carp (242.32 ± 0.58 g) were fed diets containing graded levels of iron at 12.15 (basal diet), 35.38, 63.47, 86.43, 111.09, 136.37 and 73.50 mg/kg for 60 days. Subsequently, a challenge test was conducted by infection with Flavobacterium columnare to investigate the effects of dietary iron on gill immune function and structural integrity in young grass carp. First, the results indicated that compared with the optimal iron level, iron deficiency decreased lysozyme (LZ) and acid phosphatase (ACP) activities, complement 3 (C3), C4 and immunoglobulin M (IgM) contents, and down-regulated the mRNA levels of antibacterial peptides, anti-inflammatory cytokines (except IL-4/13B), inhibitor of κBα (IκBα), target of rapamycin (TOR) and ribosomal protein S6 kinase 1 (S6K1). In contrast, iron deficiency up-regulated the mRNA levels of pro-inflammatory cytokines (except IL-6 and IFN-γ2), nuclear factor κB p65 (NF-κBp65), IκB kinases α (IKK), IKKβ, IKKγ, eIF4E-binding protein 1 (4E-BP1) and 4E-BP2 in gill of young grass carp, indicating that iron deficiency could impair immune function in fish gill. Second, iron deficiency down-regulated the mRNA levels of inhibitor of apoptosis protein (IAP) and myeloid cell leukemia 1 (Mcl-1), decreased activities and mRNA levels of antioxidant enzymes, down-regulated the mRNA levels of NF-E2-related factor 2 (Nrf2) and tight junction proteins (except claudin-12 and -15), and simultaneously increased malondialdehyde (MDA), protein carbonyl (PC) and reactive oxygen species (ROS) contents. Iron deficiency also up-regulated mRNA levels of cysteinyl aspartic acid-protease (caspase) -2, -7, -8, -9, Fas ligand (FasL), apoptotic protease activating factor-1 (Apaf-1), B-cell-lymphoma-2 associated X protein (Bax), p38 mitogen-activated protein kinase (p38MAPK), Kelch-like ECH-associating protein (Keap) 1a, Keap1b, claudin-12, -15 and MLCK, indicating that iron deficiency could disturb the structural integrity of gill in fish. Third, iron excess impaired immune function and structural integrity in gill of young grass carp. Forth, there was a better effect of ferrous fumarate than ferrous sulfate in young grass carp. Finally, the iron requirements based on ability against gill rot, ACP activity and MDA content in gill of young grass carp were estimated to be 76.52, 80.43 and 83.17 mg/kg, respectively.

Anti-Inflammatory Effect of Taurine in Burned Patients

PURPOSE

Burn induced inflammatory response can be mediated by reactive oxygen metabolites and accompanied by multiple organ dysfunction. Taurine has protective effects against various inflammatory conditions. The aim of this study was to determine the effect of Taurine supplement in thermal burn victims.

METHODS

Thirty patients with severe thermal burns were enrolled in this randomized double-blinded clinical trial. These patients were randomly divided into two equal groups (namely Control and Taurine groups), where both received isocaloric and isonitrogenous formula. One group was supplemented with 50 mg/kg of Taurine per day for a duration of 10 days. Blood samples were obtained to measure Interleukin-10 (IL-10), high-sensitivity C-reactive protein (hs-CRP), and Tumor Necrosis Factor alpha (TNF-α) levels at the beginning and the end of the study.

RESULTS

Change in serum level of IL-10 in Taurine group was more than Control group [-13.60(-31.40, -10.40) compared to -4.00(-20.00, -0.20) respectively; P = 0.030]. This change was significant in patients with more than 30% TBSA of burn [-14.20(-31.40, -10.40) compared to -2.40(-9.60, 0.40) respectively; P = 0.013]. As for the hs-CRP and TNF-α levels, the difference between the two groups were not significant.

CONCLUSION

Based on the results obtained, Taurine supplement showed a positive outcome on anti-inflammatory cytokine IL-10 in all burn patients. This effect was even more significant in patients with higher percentage of burn area. Taurine had no significant effect on the inflammatory marker hs-CRP and the pro-inflammatory cytokine TNF-α level. For a more thorough verification, measurement of a wider range of inflammatory cytokines in more frequent time intervals are suggested.

Role of volume-regulated and calcium-activated anion channels in cell volume homeostasis, cancer and drug resistance

Volume-regulated channels for anions (VRAC) / organic osmolytes (VSOAC) play essential roles in cell volume regulation and other cellular functions, e.g. proliferation, cell migration and apoptosis. LRRC8A, which belongs to the leucine rich-repeat containing protein family, was recently shown to be an essential component of both VRAC and VSOAC. Reduced VRAC and VSOAC activities are seen in drug resistant cancer cells. ANO1 is a calcium-activated chloride channel expressed on the plasma membrane of e.g., secretory epithelia. ANO1 is amplified and highly expressed in a large number of carcinomas. The gene, encoding for ANO1, maps to a region on chromosome 11 (11q13) that is frequently amplified in cancer cells. Knockdown of ANO1 impairs cell proliferation and cell migration in several cancer cells. Below we summarize the basic biophysical properties of VRAC, VSOAC and ANO1 and their most important cellular functions as well as their role in cancer and drug resistance.

Effects of high fructose and salt feeding on systematic metabonome probed via (1) H NMR spectroscopy

Diets rich in high fructose and salt are increasingly popular in our daily life. A combination consumption of excessive fructose and salt can induce insulin resistance (IR) and hypertension (HT), which are major public health problems around the world. However, the effects of high fructose and salt on systematic metabonome remain unknown, which is very important for revealing the molecular mechanism of IR and HT induced by this dietary pattern. The metabolic profiling in urine, plasma, and fecal extracts from high fructose and salt-fed rats was investigated by use of (1) H nuclear magnetic resonance (NMR)-based metabonomics approach in this study. Multivariate analysis of NMR data showed the effects of high fructose and salt on the global metabonome. The metabolite analysis in urine and fecal extracts showed the time-dependent metabolic changes, which displayed metabonomic progression axes from normal to IR and HT status. The changes of 2-oxoglutarate, creatine and creatinine, citrate, hippurate, trimethylamine N-oxide (TMAO), and betaine in urine, together with gut microbiota disorder in feces, were observed at the preliminary formation stage of IR and HT (fourth week). At the severe stage (eighth week), the previously mentioned metabolic changes were aggravated, and the changes of lipid and choline metabolism in plasma suggested the increased risk of cardiovascular diseases. These findings provide an overview of biochemistry consequences of high fructose and salt feeding and comprehensive insights into the progression of systematic metabonome for IR and HT induced by this dietary pattern.

A1H NMR-based metabonomic investigation of time-dependent metabolic trajectories in a high salt-induced hypertension rat model

The time-dependent metabolic profiles in urine, plasma and feces of salt-fed hypertensive rats were systematically investigated using NMR-based metabonomics.

Physiological role of taurine--from organism to organelle

Taurine is often referred to as a semi-essential amino acid as newborn mammals have a limited ability to synthesize taurine and have to rely on dietary supply. Taurine is not thought to be incorporated into proteins as no aminoacyl tRNA synthetase has yet been identified and is not oxidized in mammalian cells. However, taurine contributes significantly to the cellular pool of organic osmolytes and has accordingly been acknowledged for its role in cell volume restoration following osmotic perturbation. This review describes taurine homeostasis in cells and organelles with emphasis on taurine biophysics/membrane dynamics, regulation of transport proteins involved in active taurine uptake and passive taurine release as well as physiological processes, for example, development, lung function, mitochondrial function, antioxidative defence and apoptosis which seem to be affected by a shift in the expression of the taurine transporters and/or the cellular taurine content.

System responses to chronic cold stress probed via1H NMR spectroscopy in plasma and urine matrices

The metabolic pathways in plasma and urine revealed the biochemical changes under chronic cold stress from a systematic and holistic view.

Taurine induces the apoptosis of breast cancer cells by regulating apoptosis-related proteins of mitochondria

Taurine (Tau), the most abundant free amino acid in humans has numerous potential health benefits through its antioxidant and anti-inflammatory properties. However, limited studies have assessed its effect on tumors and the antitumor mechanism remains unknown. The present study investigated the cellular and molecular changes induced by Tau, leading to the induction of apoptosis in human breast cancer cell lines MCF-7 and MDA-MB-231. MCF-7 is p53 proficient (p53+/+) and MDA-MB-231 is a p53 null mutant (p53-/-). Cell proliferation and viability were assessed by MTT. Flow cytometry and hoechst33342 fluorescent staining were employed to detect apoptosis. Spectrophotometry was used to detect caspase-3 activity. Reverse transcription-polymerase chain reaction and western blot analysis were used to detect the levels of mRNA and proteins of p53-upregulated modulator of apoptosis (PUMA), Bax and Bcl-2. Finally, the affect of Tau on the growth of MDA-MB-231-cell-nude mice xenografts was examined. In the study, Tau inhibited growth and induced apoptosis of the two cell lines in a concentration- and time-dependent manner. Notably, the inhibitory effect of Tau on p53-/- cancer cells was clearly significant compared to the p53+/+ cancer cells. Further studies showed that Tau promoted apoptosis in human breast cancer cells and inhibited the growth of tumor in nude mice by inducing the expression of PUMA, which further up- and downregulated the expression of Bax and Bcl-2 protein, giving rise to increased activation of caspase-3. Collectively, these results indicate that Tau is a potent candidate for the chemotherapy of breast cancer through increasing the PUMA expression independent of p53 status.

Uptake and biological effects of synthetic glucocorticoids in common carp (Cyprinus carpio)

Uptake and biological effects of synthetic glucocorticoids (GCs) were analyzed using common carp (Cyprinus carpio). Fish were exposed to clobetasol propionate (CP) or clobetasone butyrate (CB) individually or in mixture at 1 μg L(-1) for 21 days. Bioconcentration factor (BCF) of CB was calculated as 100, and BCF of CP was less than 16. No effects were found in fish erythrocyte and leukocyte numbers and serum glucose levels after exposure to the selected GCs. On the other hand, serum concentrations of free amino acids significantly increased in GC-exposed groups. Thus, exposures to synthetic GCs at relatively low concentrations seemed to cause enhancement of protein degradation and subsequent increase of serum free amino acids without a corresponding increase in serum glucose levels, an effect which might be related to partial induction of gluconeogenesis by GC.

Prediction of survival for patients with advanced colorectal cancer using (1) H High-resolution magic angle spinning nuclear MR spectroscopy

PURPOSE

To evaluate whether the metabolic profiles of colorectal cancer specimens can be used for prediction of survival.

MATERIALS AND METHODS

The metabolic profiles of colorectal cancer tissues were determined using the high-resolution magic angle spinning (HR MAS) nuclear magnetic resonance (NMR) technique (16.4 T). HR MAS analysis was performed for 52 tissues taken from patients classified as survivors and nonsurvivors (30). Quantitative analysis was performed for each spectrum. Receiver operating characteristic (ROC) curves were used to evaluate the potential to predict patient survival over 5.5 years.

RESULTS

Analysis of (1) H NMR spectra led to the identification and quantitative analysis of 30 metabolites. A significant increase in the Tau/Gly and Tau/MI ratios were associated with long-term survival (P = 0.004 and P = 0.003, respectively). ROC analysis indicated that the Tau/MI ratio had the best predictive value for survival (sensitivity 64.7% and specificity 100%). Good predictive value of survival was found for Tau/Gly ratio (sensitivity 63.6% and specificity 96.3%). Moreover, the Glu/Gln metabolic ratio with a cutoff level of 1.74 was predictive of survival with a sensitivity of 83.3% and a specificity of 85.7%.

CONCLUSION

Our results indicate that HR MAS spectroscopy is potentially useful for survival prediction in advanced colorectal cancer.

An integrated metabonomic approach to studying metabolic profiles in rat models with insulin resistance induced by high fructose

Insulin resistance (IR) is a common risk factor for the development of metabolic diseases, and has gradually become a hot issue for research. It was reported that excessive feeding with high fructose induced insulin resistance in both humans and rats. The aim of this study was to investigate the progression of IR and identify potential biomarkers in urine, plasma and fecal extracts of high fructose-fed rats using a (1)H NMR-based metabonomics approach. The biochemical analysis was also performed. The levels of pyruvate and lactate in the plasma of the IR model rats were reduced significantly, and the levels of citrate and α-ketoglutaric acid (α-KG) in their urine, and the levels of succinate in their feces also decreased, suggesting perturbation of energy metabolism. Decreased levels of taurine in urine and fecal extracts during the whole experiment, together with increased levels of creatine/creatinine in urine, revealed liver and kidney injuries. Decreased levels of choline-containing metabolites in urine and increased levels of betaine in urine and plasma demonstrated altered transmethylation. Changes in hippurate, acetate, propionate and n-butyrate levels suggested disturbance of the intestinal flora in the IR rats. This study indicated that (1)H NMR-based metabonomics can provide biochemical information on the progression of IR and offers a non-invasive means for the discovery of potential biomarkers.

1H HR-MAS NMR spectroscopy of tumor-induced local metabolic "field-effects" enables colorectal cancer staging and prognostication

Colorectal cancer (CRC) is a major cause of morbidity and mortality in developed countries. Despite operative advances and the widespread adoption of combined-modality treatment, the 5-year survival rarely exceeds 60%. Improving our understanding of the biological processes involved in CRC development and progression will help generate new diagnostic and prognostic approaches. Previous studies have identified altered metabolism as a common feature in carcinogenesis, and quantitative measurement of this altered activity (metabonomics/metabolomics) has the potential to generate novel metabolite-based biomarkers for CRC diagnosis, staging and prognostication. In the present study we applied high-resolution magic angle spinning nuclear magnetic resonance (HR-MAS NMR) spectroscopy to analyze metabolites in intact tumor samples (n = 83) and samples of adjacent mucosa (n = 87) obtained from 26 patients undergoing surgical resection for CRC. Orthogonal partial least-squares discriminant analysis (OPLS-DA) of metabolic profiles identified marked biochemical differences between cancer tissue and adjacent mucosa (R(2) = 0.72; Q(2) = 0.45; AUC = 0.91). Taurine, isoglutamine, choline, lactate, phenylalanine, tyrosine (increased concentrations in tumor tissue) together with lipids and triglycerides (decreased concentrations in tumor tissue) were the most discriminant metabolites between the two groups in the model. In addition, tumor tissue metabolic profiles were able to distinguish between tumors of different T- and N-stages according to TNM classification. Moreover, we found that tumor-adjacent mucosa (10 cm from the tumor margin) harbors unique metabolic field changes that distinguish tumors according to T- and N-stage with higher predictive capability than tumor tissue itself and are accurately predictive of 5-year survival (AUC = 0.88), offering a highly novel means of tumor classification and prognostication in CRC.

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.

1H NMR-based metabonomics study of the urinary biochemical changes in Kansui treated rat

ETHNOPHARMACOLOGICAL RELEVANCE

The dried root of Kansui (Euphorbia kansui L.) is a commonly used and effective traditional Chinese medicine (TCM).

AIM OF THE STUDY

We combined the urinary metabolites alteration and traditional assays of Kansui-induced rats to discuss the mechanism of toxicity of Kansui.

MATERIALS AND METHODS

The Sprague-Dawley rats were dosed with 7.875g Kansui/kg weight and 15.75g Kansui/kg weight. Urine samples were collected at day -1 (before treatment), and days 7, 14 and 21 for NMR analysis. Plasma and liver and kidney tissues were collected at day 14 for biochemical assays and histopathological examination, respectively.

RESULTS

The metabonome of rats treated with Kansui differed markedly from that of the controls. This was confirmed by the histopathology of liver and kidney tissue and clinical biochemistry analysis. The toxicity of Kansui accumulated with dosing time, and persisted even when treatment was stopped. The corresponding biochemical pathways alterations included inhibited TCA cycle, increased anaerobic glycolysis, and perturbed amino acids metabolism.

CONCLUSION

The biochemical pathways disorder conjunction with histopathology changes provides new clues to evaluate the toxicity of Kansui from a systematic and holistic view.

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

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

Preparation and evaluation of PLGA microparticles as carrier for the pulmonary delivery of rhIL-2 : I. Effects of some formulation parameters on microparticle characteristics

In this study, recombinant human interleukin-2 (rhIL-2) containing poly(lactic-co-glycolic acid) (PLGA) microparticles were prepared for pulmonary administration by modified w/o/w double emulsion solvent extraction method and the effects of various formulation parameters on the physicochemical properties of the microparticles were investigated. Microparticles in suitable size for pulmonary administration (4.02 µm) were obtained by increasing dichloromethane volume used in the organic phase. Also, a very high encapsulation efficiency (99.22%) value could be reached in these microparticles. In the sodium dodecyl sulphate-polyacrylamide gel electrophoresis analysis, rhIL-2 extracted from microparticles having a similar band with native rhIL-2 showed that the protein was not affected by the encapsulation process. The release curves of microparticles exhibited a biphasic fashion, characterized by a fast release phase at initial 1 day, followed by a slower one on the remaining days. Bioactivity investigations using T cells show that rhIL-2 encapsulated in PLGA microparticles retain their biological activity.

Genome-wide identification of long noncoding RNAs in CD8+ T cells

Previous research into the molecular mechanisms that underlie Ag-specific CD8(+) T cell differentiation and function has largely focused on the role of proteins. However, it is now apparent that the mammalian genome expresses large numbers of long (>200 nt) nonprotein-coding RNAs (ncRNAs), and there is increasing evidence that these RNAs have important regulatory functions, particularly in the regulation of epigenetic processes underpinning cell differentiation. In this study, we show that CD8(+) T cells express hundreds of long ncRNAs, many of which are lymphoid-specific and/or change dynamically with lymphocyte differentiation or activation. Numerous ncRNAs surround or overlap immunologically important protein-coding genes and can be predicted to function via a range of regulatory mechanisms. The overlap of many long ncRNAs expressed in CD8(+) T cells with microRNAs and small interfering RNAs further suggests that long ncRNAs may be processed into and exert their effects via smaller functional species. Finally, we show that the majority of long ncRNAs expressed in CD8(+) T cells harbor signatures of evolutionary conservation, secondary structures, and/or regulated promoters, further supporting their functionality. Taken together, our findings represent the first systematic discovery of long ncRNAs expressed in CD8(+) T cells and suggest that many of these transcripts are likely to play a role in adaptive immunity.

Taurine and guanidinoethanesulfonic acid (GES) differentially affects the expression and phosphorylation of cellular proteins in C6 glial cells

Effects of taurine and guanidinoethanesulfonic acid (GES), a taurine transport inhibitor, on the expression and phosphorylation of cellular proteins in C6 glial cells were examined using two-dimensional (2-D) gel electrophoresis and 2-D immunoblots. 2-D gels stained with Coomassie Blue or SYPRO Ruby showed differential distribution patterns of cellular proteins in the control, taurine-supplemented and GES-supplemented cells. 2-D immunoblot analysis using the anti-phosphotyrosine antibody recognized only few immuno-reactive proteins in all three samples, and their distribution patterns were different. On the other hand, 2-D immunoblot analysis using the anti-phosphothreonine antibody recognized many immuno-reactive proteins with distinctly different distribution patterns in the control, taurine-supplemented and GES-supplemented cells. In GES-supplemented cells, the relative number of the anti-phosphotyrosine immuno-reactive protein spots increased modestly, whereas the relative number of the anti-phosphothreonine immuno-reactive protein spots decreased markedly than those in the control and taurine-supplemented cells.

Hypoglycaemic, antioxidative and nephroprotective effects of taurine in alloxan diabetic rabbits

The therapeutic potential of taurine was investigated under diabetic conditions. Alloxan diabetic rabbits were treated daily for three weeks with 1% taurine in drinking water. The following parameters were measured: 1) serum glucose, urea, creatinine and hydroxyl free radical (HFR) levels; 2) blood glutathione redox state; 3) urine albumin concentration; 4) hepatic and renal HFR levels, GSH/GSSG ratios and the activities of catalase, superoxide dismutase and the enzymes of glutathione metabolism; 5) renal NADPH oxidase activity; 6) the rates of renal and hepatic gluconeogenesis. Histological studies of kidneys were also performed. Taurine administration to diabetic rabbits resulted in 30% decrease in serum glucose level and the normalisation of diabetes-elevated rate of renal gluconeogenesis. It also decreased serum urea and creatinine concentrations, attenuated diabetes-evoked decline in GSH/GSSG ratio and abolished hydroxyl free radicals accumulation in serum, liver and kidney cortex. Animals treated with taurine exhibited elevated activities of hepatic gamma-glutamylcysteine syntetase and renal glutathione reductase and catalase. Moreover, taurine treatment evoked the normalisation of diabetes-stimulated activity of renal NADPH oxidase and attenuated both albuminuria and glomerulopathy characteristic of diabetes. In view of these data, it is concluded that: 1) diminished rate of renal gluconeogenesis seems to contribute to hypoglycaemic effect of taurine; 2) taurine-induced increase in the activities of catalase and the enzymes of glutathione metabolism is of importance for antioxidative action of this amino acid and 3) taurine nephroprotective properties might result from diminished renal NADPH oxidase activity. Thus, taurine seems to be beneficial for the therapy of both diabetes and diabetic nephropathy.

Sézary syndrome is a unique cutaneous T-cell lymphoma as identified by an expanded gene signature including diagnostic marker molecules CDO1 and DNM3

Sezary syndrome (SS) is a rare, aggressive CD4+ cutaneous T-cell lymphoma (CTCL); molecular traits differentiating SS from nonleukemic mycosis fungoides (MF) and from inflammatory skin diseases (ID) are not sufficiently characterized. Peripheral blood mononuclear cells (PBMC) of 10 SS patients and 10 healthy donors (HD) were screened by Affymetrix U133Plus2.0 chips for differential gene expression. Ten candidate genes were confirmed by qRT-PCR to be significantly overexpressed in CD4+ T cells of SS versus HD/ID. For easier clinical use, these genes were re-analyzed in PBMC; qRT-PCR confirmed five novel (DNM3, IGFL2, CDO1, NEDD4L, KLHDC5) and two known genes (PLS3, TNFSF11) to be significantly overexpressed in SS. Multiple logistic regression analysis revealed that CDO1 and DNM3 had the highest discriminative power in combination. Upon comparison of PBMC and skin samples of SS versus MF, CDO1 and DNM3 were found upregulated only in SS. Using anti-CDO1 antisera, differential expression of CDO1 protein was confirmed in SS CD4+ T cells. Interestingly, DNM3 and CDO1 are known to be regulated by SS-associated transcription factors TWIST1 and c-myb, respectively. Furthermore, CDO1 catalyzes taurine synthesis and taurine inhibits apoptosis and promotes chemoprotection. In summary, CDO1 and DNM3 may improve the diagnosis of SS and open novel clues to its pathogenesis.

Taurine deficiency and apoptosis: findings from the taurine transporter knockout mouse

Apoptosis is characterized by cell shrinkage, nuclear condensation, DNA-fragmentation and apoptotic body formation. Compatible organic osmolytes, e.g. taurine, modulate the cellular response to anisotonicity and may protect from apoptosis. Taurine transporter knockout mice (taut-/- mice) show strongly decreased taurine levels in a variety of tissues. They develop clinically important age-dependent diseases and some of them are characterized by apoptosis. Increased photoreceptor apoptosis leads to blindness of taut-/- mice at an early age. The taurine transporter may not be essential for the differentiation of photoreceptor cells, but many mature cells do not survive without an intact taurine transporter. The olfactory epithelium of taut-/- mice also exhibits structural and functional abnormalities. When compared with wild-types, taut-/- mice have a significantly higher proliferative activity of immature olfactory receptor neurons and an increased number of apoptotic cells. This is accompanied by electrophysiological findings indicating a reduced olfactory sensitivity. Furthermore, taut-/- and taut+/- mice develop moderate unspecific hepatitis and liver fibrosis beyond 1 year of age where hepatocyte apoptosis and activation of the CD95 system are pronounced.

Physiologically high concentrations of 17β-estradiol enhance NF-κB activity in human T cells

Estrogen has diverse effects on inflammation and immune responses. That pregnancy is associated with remission of some autoimmune diseases and exacerbation of others suggests that physiological fluctuation in estrogen levels could affect the immune responses in humans. However, the molecular basis for these phenomena is poorly understood. We hypothesized that fluctuations of estrogen levels modulate intracellular signaling for immune responses via estrogen receptors (ERs). In reporter assays, 17β-estradiol (E2) at a physiologically high concentration increased the activity of NF-κB in Jurkat cells stimulated by PMA/ionomycin or TNF-α. Overexpression and RNA interference experiments suggested that the effects were mediated through ERβ. Immunoprecipitation assay showed that both ERα and ERβ are directly associated with NF-κB in the cell nucleus. Using chromatin immunoprecipitation assay, we confirmed that ERα and ERβ associated with NF-κB and steroid hormone coactivators at the promoter region of NF-κB regulated gene. Considering that NF-κB regulates the expression of various genes essential for cell growth and death, estrogen could regulate the fate of T cells by affecting the activity of NF-κB. To determine whether E2 alters the fate of T cells, we investigated E2 actions on T cell apoptosis, a well-known NF-κB-mediated phenomenon. E2 increased apoptosis of Jurkat cells and decreased that of human peripheral blood T cells. Our results indicate that E2 at a physiologically high concentration modulates NF-κB signaling in human T cells via ERβ and affects T cell survival, suggesting that these actions may underlie the gender differences in autoimmune diseases.

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.

Effect of interleukin-15 on effector and regulatory function of anti-CD3/anti-CD28-stimulated CD4(+) T cells

Autologous transfer of anti-CD3/anti-CD28 (CD3/CD28)-activated CD4(+) T cells may benefit patients receiving autologous stem cell transplant with severe CD4 lymphopenia. Interleukin (IL)-15, an IL-2-like cytokine that promotes T cell survival may enhance immune reconstitution in conjunction with adoptive immunotherapy. We investigated the effect of IL-15 on effector and regulatory function of CD3/CD28-activated CD4(+) T cells. IL-15 upregulated CD45RO and CD25 whereas it down regulated CD62L expression of CD3/CD28-stimulated CD4(+) T cells. Both type 1 (IFN-gamma, tumor necrosis factor (TNF)-alpha) and type 2 (IL-5 and IL-10) production by CD3/CD28-activated CD4(+) T cells was further enhanced by IL-15. Co-culture experiments revealed that CD3/CD28-activated CD4(+) T cells down regulated proliferation of autologous peripheral blood lymphocytes (PBLs) and CD8(+) PBL subsets upon TCR ligation, a contact-dependent effect that was further enhanced by pretreatment with IL-15. Flow cytometric analysis of cell mixture with carboxyfluorescein diacetate succinimidyl ester and Annexin-V-PE staining revealed that CD3/CD28+IL-15-activated CD4(+) T cells showed increased apoptosis over CD4(+) T cells stimulated with CD3/CD28 alone. Taken together, pretreatment of CD3/CD28-activated CD4(+) T cells with IL-15 may increase regulatory function but may aggravate activation-induced apoptosis of CD3/CD28 CD4(+) T cells.