Induction Of Apoptosis In Lymphocytes Research Articles

The histone methyltransferase KMT2D maintains cellular glucocorticoid responsiveness by shielding the glucocorticoid receptor from degradation

Because of their ability to induce lymphocyte apoptosis, glucocorticoids (GC) are widely used to treat hematological malignancies such as lymphomas and multiple myeloma. Their effectiveness is often limited, however, due to the development of glucocorticoid resistance by a variety of molecular mechanisms. Here we performed an unbiased genome-wide CRISPR screen with the human T cell leukemia cell line Jurkat to find previously unidentified genes required for GC-induced apoptosis. One such gene was KMT2D (also known as MLL2 or MLL4), which encodes a histone lysine methyltransferase whose mutations are associated with a variety of cancers, blood malignancies in particular, and are considered markers of poor prognosis. Knockout of KMT2D by CRISPR/Cas9 gene editing in Jurkat and several multiple myeloma cell lines downregulated GR protein expression. Surprisingly, this was not due to a reduction in GR transcripts, but rather to a decrease in the protein's half-life, primarily due to proteasomal degradation. Reconstitution of KMT2D expression restored GR levels. In contrast to the known ability of KMT2D to control gene transcription through covalent histone methylation, KMT2D-mediated upregulation of GR levels did not require its methyltransferase activity. Co-immunoprecipitation and proximity ligation assays found constitutive binding of KMT2D to the GR, which was enhanced in the presence of GC. These observations reveal KMT2D to be essential for stabilization of cellular GR levels, and suggest a possible mechanism by which KMT2D mutations may lead to GC resistance in some malignancies.

9-cis-retinoic acid signaling in Sertoli cells regulates their immunomodulatory function to control lymphocyte physiology and Treg differentiation

BackgroundTestis is an immune privileged organ, which prevents the immune response against sperm antigens and inflammation. Testicular cells responsible for immune tolerance are mainly Sertoli cells, which form the blood-testis barrier and produce immunosuppressive factors. Sertoli cells prevent inflammation in the testis and maintain immune tolerance by inhibiting proliferation and inducing lymphocyte apoptosis. It has been shown that 9-cis-retinoic acid (9cRA) blocks ex vivo apoptosis of peripheral blood lymphocytes and promotes the differentiation of Treg cells in the gut. However, the role of retinoid signaling in regulating the immune privilege of the testes remains unknown.ObjectiveThe aim of this study was to determine whether 9cRA, acting via the retinoic acid receptors (RAR) and the retinoic X receptors (RXR), controls the immunomodulatory functions of Sertoli cells by influencing the secretion of anti-inflammatory/pro-inflammatory factors, lymphocyte physiology and Treg cell differentiation.MethodsExperiments were performed using in vitro model of co-cultures of murine Sertoli cells and T lymphocytes. Agonists and antagonists of retinoic acid receptors were used to inhibit/stimulate retinoid signaling in Sertoli cells.ResultsOur results have demonstrated that 9cRA inhibits the expression of immunosuppressive genes and enhances the expression of pro-inflammatory factors in Sertoli cells and lymphocytes, increases lymphocyte viability and decreases apoptosis rate. Moreover, we have found that 9cRA blocks lymphocyte apoptosis acting through both RAR and RXR and inhibiting FasL/Fas/Caspase 8 and Bax/Bcl-2/Caspase 9 pathways. Finally, we have shown that 9cRA signaling in Sertoli cells inhibits Treg differentiation.ConclusionCollectively, our results indicate that retinoid signaling negatively regulates immunologically privileged functions of Sertoli cells, crucial for ensuring male fertility. 9cRA inhibits lymphocyte apoptosis, which can be related to the development of autoimmunity, inflammation, and, in consequence, infertility.

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.

Protein arginine N-methyltransferase 4 (PRMT4) contributes to lymphopenia in experimental sepsis

BackgroundOne hallmark of sepsis is the reduced number of lymphocytes, termed lymphopenia, that occurs from decreased lymphocyte proliferation or increased cell death contributing to immune suppression. Histone modification enzymes regulate...

High Platelet Lymphocyte Ratio as Predictor of Bad Outcome in Patient with Acute Ischemic Stroke

Background/Aim: Stroke is a major cause of death and disability worldwide. Inflammatory markers for poor outcomes in stroke patients have been widely studied, but these examinations are often constrained by limited costs and facilities. Platelet lymphocyte ratio is one of the markers of inflammation that is easily examined, only a few researches were studied on stroke patients, especially ischemic type. This article aimed to understanding high platelet lymphocyte ratio as a risk factor for poor outcome in acute ischemic stroke patients. Method: The design of this research is literature review by literature from 32 journal and 5 textbooks. Journals obtained from search engines Pubmed, Google Scholar, and NCBI. Result: Based on the results of the literature review, circulating platelets play an important role in the development and resolution, not only because of their direct effect on the endothelium but also by releasing inflammatory mediators. Acute ischemic stroke will induce lymphocyte apoptosis, which causes impaired immune system. High platelet counts and low lymphocytes contribute to micro-thrombus formation, which increases the risk of stroke and has a poor prognosis in patient. Conclusion: There is an increase platelet lymphocyte ratio can be an independent predictor of poor outcome in acute ischemic stroke patient Keywords: acute ischemic, stroke, platelet lymphocyte ratio, poor outcome

Goose Nephritic Astrovirus Infection of Goslings Induces Lymphocyte Apoptosis, Reticular Fiber Destruction, and CD8 T-Cell Depletion in Spleen Tissue.

The emergence of a novel goose nephritic astrovirus (GNAstV) has caused economic losses to the Chinese goose industry. High viral load is found in the spleen of goslings infected with GNAstV, but pathological injuries to the spleen due to GNAstV are largely unknown. In this study, 50 two-day-old goslings were infected orally with GNAstV, and 50 goslings were treated with PBS as control. Spleens were collected at different times following infection to assess damage. GNAstV infection caused visceral gout and urate deposition in joints, and resulted in 16% mortality. GNAstV was found in the lymphocytes and macrophages within the spleen. Lymphocyte loss, especially around the white pulp, and destruction and decline in the number of reticular fibers was observed in GNAstV-infected goslings. Moreover, in GNAstV-infected goslings, ultrahistopathological examination found that splenic lymphocytes exhibited condensed chromatin and apoptotic bodies, and reticular cells displayed damage to plasma membrane integrity and swollen mitochondria. Furthermore, TUNEL staining confirmed apoptosis of lymphocytes, and the mRNA levels of Fas and FasL were significantly increased in the GNAstV-infected goslings. In addition, GNAstV infection reduced the number and protein expression of CD8. In conclusion, GNAstV infection causes lymphocyte depletion, reticular cell necrosis, reticular fiber destruction, lymphocyte apoptosis, and reduction in CD8 levels, which contribute to spleen injury.

Is the neutrophil-to-lymphocyte ratio a useful prognostic indicator in melanoma patients?

The neutrophil-to-lymphocyte ratio (NLR) is gaining traction as a biomarker with utility in a variety of malignancies including melanoma. Intact lymphocyte function is necessary for tumor surveillance and destruction, and neutrophils play a role in suppressing lymphocyte proliferation and in the induction of lymphocyte apoptosis. Early research in melanoma indicates that in high-risk localized melanoma, a high NLR is correlated with worse overall and disease-free survival. Similarly, in metastatic melanoma treated with both metastasectomy and immunotherapies, an elevated NLR is predictive of shortened overall survival and progression-free survival. Future studies incorporating NLR into more traditional melanoma prognostic markers while employing more granular outcomes, are needed to realize the full potential of NLR.

Neurotoxic Anatoxin-a Can Also Exert Immunotoxicity by the Induction of Apoptosis on Carassius auratus Lymphocytes in vitro When Exposed to Environmentally Relevant Concentrations.

Hazardous anatoxin-a (ANTX-a) is produced by freshwater algal blooms worldwide, which greatly increases the risk of consumer exposure. Although ANTX-a shows widespread neurotoxicity in aquatic animals, little is known about its mechanism of action and biotransformation in biological systems, especially in immunobiological models. In this study, transmission electron microscopy results showed that ANTX-a can destroy lymphocytes of Carassius auratus in vitro by inducing cytoplasmic concentration, vacuolation, and swollen mitochondria. DNA fragmentations clearly showed a ladder pattern in agarose gel electrophoresis, which demonstrated that the apoptosis of fish lymphocytes was caused by exposure to ANTX-a. Flow cytometry results showed that the apoptotic percentage of fish lymphocytes exposed to 0.01, 0.1, 1, and 10 mg/L of ANTX-a for 12 h reached 18.89, 22.89, 39.23, and 35.58%, respectively. ANTX-a exposure induced a significant increase in reactive oxygen species (ROS) and malonaldehyde (MDA) in lymphocytes. The activities of superoxide dismutase (SOD), catalase (CAT), glutathione reductase (GR), glutathione peroxidase (GPx), and the glutathione (GSH) content of the 0.01 mg/L ANTX-a-treated group decreased significantly by about 41, 46, 67, and 54% compared with that of the control group (p < 0.01), respectively. Although these observations were dose-dependent, these results suggested that ANTX-a can induce lymphocyte apoptosis via intracellular oxidative stress and destroy the antioxidant system after a short exposure time of only 12 h. Besides neurotoxicity, ANTX-a may also be toxic to the immune system of fish, even when the fish are exposed to environmentally relevant concentrations, which clearly demonstrated that the potential health risks induced by ANTX-a in aquatic organisms requires attention.

Glyphosate induces lymphocyte cell dysfunction and apoptosis via regulation of miR-203 targeting of PIK3R1 in common carp (Cyprinus carpio L.)

Glyphosate is a widely used pesticide worldwide. The problem surrounding glyphosate is worth investigating, especially with its increased use, and an increasing number of studies have found that the toxic effect of glyphosate is objective. MiR-203 was seldom found in fish diseases or glyphosate researches. This article aims to explore the effect of miR-203 on carp lymphocytes during glyphosate exposure. Therefore, acridine orange/ethidium bromide (AO/EB) and flow cytometry were carried out to evaluate apoptosis, and we also detected CYPs (CYP1A1, CYP1B1, CYP1C), cytokine secretion (IL-1β, IL-8, IL-10, IFN-γ, TNF-α), inflammatory factors (NF-κB, cox-2), and the expression of miR-203 and the PI3K/AKT pathway by RT-PCR and Western blot analyses. Our results demonstrated that glyphosate exposure could induce lymphocyte apoptosis via regulation of miR-203 targeting of PI3K/AKT, which was accompanied by CYPs activation, abnormal cytokine expression and an inflammatory response. These results show that glyphosate is not nontoxic to fish and provide new insights for the usage of glyphosate as an herbicide in the future.

Induction of lymphocyte apoptosis in healthy individuals and patients with rheumatoid arthritis under “cellular neighborhood” in vitro

The aim of the study was to investigate the features of T-lymphocyte apoptosis induced by components of autologous apoptotic cultures in vitro in norm and rheumatoid arthritis in the context of «cellular neighborhood».Materials and methods. Subjects of the study were blood samples of patients with rheumatoid arthritis (RA) and healthy women of comparable age. Developed protocol allowed to differentially evaluate the parameters of proliferation, early and late stages of apoptosis in the «primary» (CFSE-) and «secondary» (CFSE+) induced apoptotic T-lymphocyte cultures. It was estimated the effect of cellular and humoral components of unstimulated, anti-CD3- and dexamethasone-stimulated cells under the conditions of overcrowding and depleted culture media on autologous lymphocytes, cultured under physiological conditions, in norm and RA.Results. Comparative qualitative analysis revealed the features of the processes of T-lymphocyte apoptosis in norm and pathology. Also, the parameters of early and late stages of apoptosis of a «primary» induced culture and «secondary» induced cells after transferring the cellular and humoral components of apoptotic cultures did not differ significantly either initially or during culturing in both investigated groups. But it was a significant increase in the amount of living T-cells in «primary»-induced unstimulated and dexamethasone-stimulated RA patients’ cultures compared to similar donors’ cultures.Conclusion. There was no difference between stimulated with anti-CD3 antibodies cells and the «secondary» induced cultures. Taking into account the absence of significant differences in the parameters of activation apoptosis, the increased number of living cells in RA patients’ cultures relative to donors’ is evidence of contribution of non-autonomous apoptosis effects to cellular homeostasis in RA.

Hypothyroidism-related zinc deficiency leads to suppression of T lymphocyte activity.

Hypothyroidism has been shown to induce immunosuppression and both the thyroid status and immunity are affected by zinc deficiency. However, the impact of hypothyroidism on zinc metabolism and its possible relationship with the immune status has not yet been deeply explored. Here, our aim was to study whether hypothyroidism may alter zinc metabolism and thus lead to the impairment of T lymphocyte activity. Variations in the distribution of zinc in the body were evaluated in PTU-treated hypothyroid mice. The effects of hypothyroidism and zinc deficiency were studied on T lymphocyte proliferation after stimulation both in vitro and in vivo. For in vitro assays, thyroid hormone-free or zinc chelator (TPEN or DTPA)-supplemented media were used. For in vivo assays, lymphocyte activity was evaluated in cells from hypothyroid, T3-treated, and zinc-supplemented mice. Hypothyroid mice showed lower levels of zinc in femur and lymph nodes than controls. T3 and zinc supplementation reversed these effects. In vitro, both thyroid hormone and zinc deficiency led to a decreased response to mitogen stimulation. However, only zinc deficiency was able to induce lymphocyte apoptosis. Mitogen-stimulated T cells from hypothyroid mice showed impaired proliferation, accompanied by decreased activation of PKC and lower levels of p-ERK, effects that were reversed by T3 replacement or zinc supplementation. Our results show an important role of zinc deficiency in hypothyroid-mediated T-cell suppression and suggest the importance of evaluating zinc levels and restoring them when necessary to maintain an efficient immune response in hypothyroid patients.

BCL-2 levels do not predict azathioprine treatment response in inflammatory bowel disease, but inhibition induces lymphocyte apoptosis and ameliorates colitis in mice

In inflammatory bowel disease (IBD), inflammation is sustained by an exaggerated response of lymphocytes. This results from enhanced expression of anti-apoptotic B cell lymphoma (BCL-2) and BCL-XL associated with a diminished turnover. Azathioprine (AZA) directly targets BCL-2 family-mediated apoptosis. We investigated whether the BCL-2 family expression pattern could be used to predict treatment response to AZA and determined whether BCL-2 inhibitor A-1211212 effectively diminishes lymphocytes and ameliorates inflammation in a model of colitis. BCL-2 family expression pattern was determined by next-generation sequencing (NGS). BCL-2 inhibitor was administered orally to Il10-/- mice. Haematological analyses were performed with an ADVIA 2120 and changes in immune cells were investigated using quantitative polymerase chain reaction (qPCR) and fluorescence activated cell sorter (FACS). We determined similar expression levels of BCL-2 family members in patients with remission and patients refractory to treatment, showing that BCL-2 family expression can not predict AZA treatment response. Expression was not correlated with the modified Truelove and Witts activity index (MTWAI). BCL-2 inhibitor initiated cell death in T cells from patients refractory to AZA and reduced lymphocyte count in Il10-/- mice. FACS revealed diminished CD8+ T cells upon BCL-2 inhibitor in Il10-/- mice without influencing platelets. Tnf, Il1β, IfnƔ and Mcp-1 were decreased upon BCL-2 inhibitor. A-1211212 positively altered the colonic mucosa and ameliorated inflammation in mice. Pro-apoptotic BCL-2 inhibitor A-1211212 diminishes lymphocytes and ameliorates colitis in Il10-/- mice without inducing thrombocytopenia. BCL-2 inhibition could be a new therapy option for patients refractory to AZA.

Amniotic fluid stem cell exosomes: Therapeutic perspective.

It is widely accepted that the therapeutic potential of stem cells can be largely mediated by paracrine factors, also included into exosomes. Thus, stem cell-derived exosomes represent a major therapeutic option in regenerative medicine avoiding, if compared to stem cells graft, abnormal differentiation and tumor formation. Exosomes derived from mesenchymal stem cells (MSC) induce damaged tissue repair, and can also exert immunomodulatory effects on the differentiation, activation and function of different lymphocytes. Therefore, MSC exosomes can be considered as a potential treatment for inflammatory diseases and also an ideal candidate for allogeneic therapy due to their low immunogenicity. Amniotic fluid stem cells (AFSCs) are broadly multipotent, can be expanded in culture, and can be easily cryopreserved in cellular banks. In this study, morphology, phenotype, and protein content of exosomes released into amniotic fluid in vivo and from AFSC during in vitro culture (conditioned medium) were examined. We found that AFSC-derived exosomes present different molecules than amniotic fluid ones, some of them involved in immunomodulation, such transforming growth factor beta and hepatic growth factors. The immunomodulatory effect of AFSC's exosomes on peripheral blood mononuclear cells stimulated with phytohemagglutinin was compared to that of the supernatant produced by such conditioned media deprived of exosomes. We present evidence that the principal effect of AFSC conditioned media (without exosomes) is the induction of apoptosis in lymphocytes, whereas exposure to AFSC-derived exosomes decreases the lymphocyte's proliferation, supporting the hypothesis that the entire secretome of stem cells differently affects immune-response. © 2017 BioFactors, 44(2):158-167, 2018.

Radiation Induced Lymphocyte Apoptosis Assay and Predictive Breast Fibrosis Nomogram: First Implementation in Daily Practice in France

The radiation-induced CD8-lymphocyte apoptosis assay (RILA) adjusted by the NovaGray Breast® nomogram has been shown to significantly predict breast fibrosis risk. Recent prospective trials confirmed the predictive role of RILA in urinary, sexual or anorectal toxicity risk after prostate radiotherapy. This study aims at evaluating the daily use of this assay and its impact on current practice. Between 2007 and 2016, 304 patients benefited from the RILA assay outside of clinical trial setting. We analyzed the reasons for assay prescription, late toxicity (assessed by CTCAEv3.0 grading scale) and clinical impact of the result. For non-breast demands, RILA cutoffs for high and low values were taken from the results of the REQUITE trial and Ozsahin et al. (Clin Cancer Res, 2005) For breast tumors, all RILA results were adjusted by the nomogram developed by NovaGray based on the recent results of the multicenter prospective trial (Azria et al., Ebiomedecine 2015). 149 patients with sufficient available data were included in the analysis. 51 patients were assessed because of late toxicities after radiotherapy (RT). Of these, 36 (70.6%) had low and 15 (29.4%) intermediate/high RILA values. For breast cancer, 27 of 29 patients with toxicities (93.1%) fitted with the predictive nomogram. 13 patients were assessed before re-irradiation, and 2 saw their RT treatment cancelled because of low RILA values (one had surgery and one refused treatment). 85 patients were assessed before initial RT treatment. Of these, 36 (42.4%) were assessed because of medical history (i.e.: systemic sclerosis, lupus or polymorphous light eruption), 33 (38.9%) because the patient asked for the test, 7 (8.2%) to aid clinical decision (i.e.: proximity of organs at risk or unclear RT indication), 4 (4.7%) because of history of surgery or trauma in the treated area, 4 (4.7%) before inclusion in clinical trials which they ended excluded from, and one (1.2%) because of severe toxicity after chemotherapy. 23 of the 85 patients (27%) had treatment changes because of the test results. Seven patients with low RILA (30.4%) saw their RT treatment replaced by other treatment modalities (mastectomy, radical prostatectomy, focal treatment, hormone therapy or brachytherapy). Treatment was canceled altogether because of low RILA in 5 cases (21.8%). Eight patients (34.8%) with low RILA had changes in the RT regimen (2 total dose reduction, 3 fractionation change, 3 RT modality change towards IMRT). Three patients (13%) had the RT indication maintained despite the test results. This is the first daily clinical implementation of the RILA assay and breast nomogram risk. Interestingly, half of the patients were assessed before treatment, with a high rate of treatment change based on the results, showing the importance of predictive markers before treatment decision.

PO-0959: REQUITE: Radiation Induced Lymphocyte Apoptosis assay as a predictor for radiotherapy side effects

PO-0959: REQUITE: Radiation Induced Lymphocyte Apoptosis assay as a predictor for radiotherapy side effects

Overexpression of HO-1 Contributes to Sepsis-Induced Immunosuppression by Modulating the Th1/Th2 Balance and Regulatory T-Cell Function.

Countervailing anti-inflammatory response and immunosuppression can cause death in late sepsis. Depletion and dysfunction of T cells are critical for developing sepsis-induced immunosuppression. Heme oxygenase-1 (HO-1) has a regulatory effect on differentiation and function of T cells and anti-inflammatory properties. We therefore investigated the immunosuppressive role of HO-1 in sepsis with a focus on its effects on helper T-cell (Th) differentiation and regulatory T cells (Treg). Sepsis was induced by cecal ligation and puncture (CLP). Mice were intraperitoneally injected with zinc protoporphyrin (ZnPP; 25 mg/kg), an HO-1 inhibitor, or hemin (20 mg/kg), an HO-1 inducer, at 24 and 36 hours post-CLP. Splenocytes were isolated 48 hours post-CLP. Mice were intranasally infected with Pseudomonas aeruginosa 4 days post-CLP as a secondary pneumonia infection model. ZnPP improved survival and bacterial clearance, whereas hemin had the opposite effect in septic mice. CLP induced lymphocyte apoptosis and a proinflammatory Th1 to anti-inflammatory Th2 shift, which was attenuated by ZnPP. ZnPP attenuated the CLP-induced Treg population and protein expression of inhibitory costimulatory molecules. Furthermore, ZnPP improved survival in the secondary pneumonia infection model. Our findings suggest that HO-1 overexpression contributes to sepsis-induced immunosuppression during late phase sepsis by promoting Th2 polarization and Treg function.

Effects of 56 Fe 17+ , 12 C 6+ heavy-ion and 60 Co γ-ray irradiation in chromosome aberrations, cell cycle and apoptosis of lymphocytes

Objective To compare the radiation effects of 56Fe17+ , 12C6+ ion beams and 60Co γ-rays on chromosome aberrations, cell cycle arrest and apoptosis induction in lymphocytes. Methods Lymphocytes Peng-EBV cells were exposed to 56Fe17+ , 12C6+ ions and 60Co γ-rays with different dose (0, 0.5, 2.0 Gy) at dose rates of 0.26-0.55, 0.30-0.50 and 0.75 Gy/min, respectively. Chromosome aberration and d+ r distortion rate was assayed, and cell apoptosis and cell cycle were analyzed by flow cytometry. Results The percentage of cells with chromosome aberration increased significantly after exposure to12C6+ , 56Fe17+ ion beams and 60Co γ-rays(χ2=12.08-322.9, P<0.05), and the rate of d+ r distortion was significantly increased as well(χ2=4.06-205.37, P<0.05). The chromosome aberration rate and d+ r distortion rateinduced by 56Fe17+ and 12C6+ ion beams were higher than that of γ-rays, especially 12C6+ irradiation. The G2 phase arrest(t=-80.9-0.17, P<0.05)and cell apoptosis(t=-22.65-0.87, P<0.05)were significantly induced by each irradiation in an order of 12C6+ , γ-rays and 56Fe17+ ions from high to low. Conclusions Associated with the LET values, 12C6+ , 56Fe17+ ionbeams and 60Co γ-rays could induce chromosome aberrations, G2 phase arrest and apoptosis in human lymphocytes, where 12C6+ ion beam irradiation was much more effective. Key words: 56Fe17+ ion beam; 12C6+ ion beam; 60Co γ-rays; Chromosome aberrations; Cell apoptosis

Cytotoxic, genotoxic and biochemical markers of insecticide toxicity evaluated in human peripheral blood lymphocytes and an HepG2 cell line

This study evaluated the cyto- and genotoxic effects of three pesticides: α-cypermethrin, chlorpyrifos and imidacloprid applied in vitro to human lymphocytes and HepG2 cells for exposure times of 4 and 24 h at concentrations corresponding to OEL, ADI and REL. Assessments were made using oxidative stress biomarkers and the alkaline comet, cytokinesis-block micronucleus cytome and cell viability assays. Low doses of all three pesticides displayed DNA damaging potential, both in lymphocytes and HepG2 cells. At the tested concentrations, all three compounds induced lymphocyte apoptosis, though α-cypermethrin and chlorpyrifos were generally more cyto- and genotoxic than imidacloprid. At the tested concentrations, oxidative stress biomarkers were not significantly altered, and the effects mediated indirectly through free radicals may not have a key role in the formation of DNA damage. It is likely that the DNA damaging effects were caused by direct interactions between the tested compounds and/or their metabolites that destabilized the DNA structure. The tested pesticides had the potential for MN, NB and NPB formation and to disturb cell cycle kinetics in both cell types. There were also indications that exposure to α-cypermethrin led to the formation of crosslinks in DNA, though this would require more detailed study in the future.

Radiation Induced Lymphocyte Apoptosis: An Effective Way of “Tailoring” Radiotherapy to the Right Patients Only?

Radiation Induced Lymphocyte Apoptosis: An Effective Way of “Tailoring” Radiotherapy to the Right Patients Only?

Immunomodulatory metabolites released by the frog-killing fungus Batrachochytrium dendrobatidis.

Batrachochytrium dendrobatidis is a fungal pathogen in the phylum Chytridiomycota that causes the skin disease chytridiomycosis. Chytridiomycosis is considered an emerging infectious disease linked to worldwide amphibian declines and extinctions. Although amphibians have well-developed immune defenses, clearance of this pathogen from the skin is often impaired. Previously, we showed that the adaptive immune system is involved in the control of the pathogen, but B. dendrobatidis releases factors that inhibit in vitro and in vivo lymphocyte responses and induce lymphocyte apoptosis. Little is known about the nature of the inhibitory factors released by this fungus. Here, we describe the isolation and characterization of three fungal metabolites produced by B. dendrobatidis but not by the closely related nonpathogenic chytrid Homolaphlyctis polyrhiza. These metabolites are methylthioadenosine (MTA), tryptophan, and an oxidized product of tryptophan, kynurenine (Kyn). Independently, both MTA and Kyn inhibit the survival and proliferation of amphibian lymphocytes and the Jurkat human T cell leukemia cell line. However, working together, they become effective at much lower concentrations. We hypothesize that B. dendrobatidis can adapt its metabolism to release products that alter the local environment in the skin to inhibit immunity and enhance the survival of the pathogen.