Differential activation of NF-κB and nitric oxide in lymphocytes regulates in vitro and in vivo radiosensitivity

Insights into the radioprotective efficacy of Pterocarpus santalinus L. aqueous extract

In the present study, we have attempted a comprehensive assessment of the possible radioprotective efficacy of Pterocarpus santalinus aqueous extract (PSAE). All the studied models were gamma-irradiated with prior treatment with PSAE. First, the content of total phenols (4.061 μg/mg gallic acid equivalents), flavonoids (6.616 μg/mg quercetin equivalents), and tannins (0.008 mg/L of PSAE) were determined spectrophotometrically. Second, UHPLC-HRMS analysis was performed to identify the possible radioprotectors. Of those, santalins A & B are known for their usage as natural color in foods and alcoholic beverages identified in PSAE. Treatment was well tolerated with no side effects from PSAE. Later, it was shown that radiation-induced lethality significantly amended in PSAE-treated spleen lymphocytes as evidenced by reduced elevated levels of ROS and lipid peroxidation, restored total thiols and GSH: GSSG, inhibited DNA DSBs and cell death. Furthermore, an immunomodulation study was carried out because radiation exposure induces an inflammatory response. Our study shows that PSAE suppressed concanavalin A-induced T-cell proliferation as evidenced by CFSE dye dilution and CD69 antibody staining methods. Taken together, the current study explored the protective efficacy of PSAE from gamma radiation-inflicted injuries and hence we recommend PSAE as a potent radioprotective formulation.

Dichotomous effects of in vivo and in vitro ionizing radiation exposure on lymphatic function

On the one hand, lymphatic dysfunction induces interstitial edema and inflammation. On the other hand, the formation of edema and inflammation induce lymphatic dysfunction. However, informed by the earlier reports of undetected apoptosis of irradiated lymphatic endothelial cells (LECs) in vivo, lymphatic vessels are commonly considered inconsequential to ionizing radiation (IR)-induced inflammatory injury to normal tissues. Primarily because of the lack of understanding of the acute effects of IR exposure on lymphatic function, acute edema and inflammation, common sequelae of IR exposure, have been ascribed solely to blood vessel damage. Therefore, in the present study, the lymphatic acute responses to IR exposure were quantified to evaluate the hypothesis that IR exposure impairs lymphatic pumping. Rat mesenteric lymphatic vessels were irradiated in vivo or in vitro, and changes in pumping were quantified in isolated vessels in vitro. Compared with sham-treated vessels, pumping was lowered in lymphatic vessels irradiated in vivo but increased in vessels irradiated in vitro. Furthermore, unlike in blood vessels, the acute effects of IR exposure in lymphatic vessels were not mediated by nitric oxide-dependent pathways in either in vivo or in vitro irradiated vessels. After cyclooxygenase blockade, pumping was partially restored in lymphatic vessels irradiated in vitro but not in vessels irradiated in vivo. Taken together, these findings demonstrated that lymphatic vessels are radiosensitive and LEC apoptosis alone may not account for all the effects of IR exposure on the lymphatic system.NEW & NOTEWORTHY Earlier studies leading to the common belief that lymphatic vessels are radioresistant either did not characterize lymphatic pumping, deemed necessary for the resolution of edema and inflammation, or did it in vivo. By characterizing pumping in vitro, the present study, for the first time, demonstrated that lymphatic pumping was impaired in vessels irradiated in vivo and enhanced in vessels irradiated in vitro. Furthermore, the pathways implicated in ionizing radiation-induced blood vessel damage did not mediate lymphatic responses.

Inhibitory Effect of FMRFamide on NO Production During Immune Defense in Sepiella japonica

Neuropeptide Phe-Met-Arg-Phe-NH2 (FMRFamide), specifically existing in invertebrates, plays pivotal roles in various physiological processes. The involvement in neuroendocrine-immune regulation was explored in recent years, and it could modulate nitric oxide (NO) production under immune stress. However, detailed knowledge is still little known. In this study, we identified FMRFamide as an inhibitory factor on NO production in the immune reaction of Sepiella japonica. Firstly, Vibrio harveyi incubation caused significantly upregulated expression of FMRFamide precursor and NO synthase (NOS) in just hatched cuttlefish with quantitative Real-time PCR (qRT-PCR), which indicated that both were likely to be involved in the immune defense. The whole-mount in situ hybridization (ISH) detected FMRFamide precursor and NOS-positive signals appeared colocalization, suggesting that at histological and anatomical levels FMRFamide might interact with NOS. Next, NOS mRNA was highly significantly upregulated at 72 h when FMRFamide precursor mRNA was knocked down effectively with the RNA interference (RNAi) method; the results hinted that FMRFamide was likely to regulate NO production. Continuously, the inflammatory model was constructed in RAW 264.7 cells induced by lipopolysaccharide (LPS), FMRFamide administration resulted in a highly significant reduction of the NO level in dose- and time-response manners. Although the addition of the selected inducible NOS (iNOS) inhibitor had inhibited the NO production induced by LPS, the additional FMRFamide could still furtherly sharpen the process. Collectively, it was concluded that neuropeptide FMRFamide could indeed inhibit NO production to serve as feedback regulation at the late stage of immune response to protect hosts from excessive immune cytotoxicity. The inhibitory effect on NO production could not only be mediated by the NOS pathway but also be implemented through other pathways that needed to be furtherly explored. The results will provide data for comparing the structure and immune function of neuroendocrine-immune system (NEIS) between "advanced" cephalopods and other invertebrates and will provide new information for understanding the NEIS of cephalopods.

Pterocarpus santalinus L. extract mitigates gamma radiation-inflicted derangements in BALB/c mice by Nrf2 upregulation

Plant-based natural extracts contain several nutrients and bioactive compounds, such as phenolics and flavonoids, that possess various health-promoting activities. This study investigated the effects of polyphenols from Pterocarpus santalinus hydroalcoholic extract (PSHE) against gamma radiation-induced derangements via the upregulation of Nrf2. Ultra High Performance Liquid Chromatography Coupled to High Resolution Mass Spectrometry (UHPLC-HRMS/MS) analysis was performed to identify the possible radioprotectors. In vivo and in vitro studies, namely Real-Time-PCR (RT-PCR) analysis, Reactive Oxygen Species (ROS) scavenging activity, lipid peroxidation and GSH levels, DNA damage and cell death studies, anti-inflammatory (Sandwich ELISA), immunomodulatory studies (antibody staining), and model free radical scavenging assays, were performed. Vanillic acid, protocatechuic acid, para-hydroxybenzoic acid, chlorogenic acid, TNF-α inhibitor (Eudesmin), isoflavone (Daidzein 7-o-glucoside), astragalin (Kaempferol 3-o-glycoside), and other polyphenols were identified in PSHE using UHPLC-HRMS/MS analysis. Prophylactic administration of PSHE (-1 h) rendered more than 33% survival in mice exposed to 8 Gy whole-body-irradiation with increased mice survival and recovery of bone marrow and spleen cellularity. Real-time RT-PCR analysis showed that PSHE treatment (50 µg/mL) upregulated Nrf2, HO-1, and GPX-1 in mice splenocytes. At 50 µg/mL, PSHE reduced ROSscavenging activity, mitochondrial and spleen membrane lipid peroxidation levels, DNA damage, and cell death, and increased GSH levels. At 10 µg/mL, PSHE treatment diminished the content of IL-6 and TNF-α. At 50 µg/mL, PSHE suppressed lymphocyte proliferation. These findings indicate that polyphenols of PSHE possess marked antioxidant, anti-inflammatory, and immunomodulatory capacities, which play important roles in the prevention of radiation damage.

Time to rejuvenate ultra-low dose whole-body radiotherapy of cancer

The results of clinical trials performed from the 1930s until the end of the 20th century in which total-body ultra-low level ionizing radiation (TB-LLR) was used demonstrate that this form of treatment can be equal or superior to other systemic anti-neoplastic modalities in terms of the rates of remissions, toxicity, and side effects. In this review, we provide the rationale for TB-LLR and analyze the results of reliable clinical trials in patients with predominantly lymphoproliferative disorders but also advanced solid cancers. The doses used in these trials did not exceed 0.1-0.2 Gy per fraction and cumulative totals ranged from 1 to 4 Gy. Based on the reviewed results we conclude that it is appropriate to revive interest in and resume clinical investigations of TB-LLR in order to refine and improve the effectiveness of such treatment, whether employed alone or in combination with other anticancer strategies.

Radioprotective Effect of Gliclazide as an Anti-Hyperglycemic Agent Against Genotoxicity Induced by Ionizing Radiation on Human Lymphocytes

Objectives:

Gliclazide (GL) is widely used to reduce hyperglycemia in diabetic patients. The aim of this study was to investigate the protective effect of GL against chromosome damage induced by ionizing radiation in human blood lymphocytes.

Methods:

In this experimental study, peripheral blood samples were collected from human volunteers and treated with GL at various concentrations (5, 25, 50 or 100 μM) for three hours. Then samples were irradiated to X-ray (1.5 Gy). Blood samples were cultured with mitogenic stimulation. The frequencies of micronuclei in cytokinesis-blocked binucleated lymphocytes were determined in the different samples. The antioxidant activities of GL were assayed by two different methods as 1,1-diphenyl-2-picryl hydrazyl radical (DPPH) free radical scavenging and reducing antioxidant power assays.

Results:

GL significantly reduced the percentage of micronuclei in lymphocytes which were irradiated. The maximum radioprotection in the reduction of percentage of micronuclei in lymphocytes was observed at 100 μM of GL with 52% efficacy. GL exhibited excellent free radical scavenging activity and reducing power at concentration dependent activities. The IC50 values of GL were lower than ascorbic acid. Higher potencies were observed in the antioxidant activities for GL than ascorbic acid in both methods.

Conclusion:

This data exhibits that GL is a powerful radioprotective agent that could protect healthy cells against the chromosome damage induced by ionizing radiation through antioxidant activity. The radioprotective effect is new indication of GL for patients' protection against side effect induced by ionizing radiation.

Radioprotective effect of olanzapine as an anti-psychotic drug against genotoxicity and apoptosis induced by ionizing radiation on human lymphocytes

Olanzapine (OLA), is prescribed as an anti-psychotic medicine in schizophrenia patients. In this study, the protective effect of OLA against genotoxicity and apoptosis induced by ionizing radiation in human healthy lymphocytes was evaluated. At first, the antioxidant activities of OLA were assayed by two different methods as free radical scavenging with DPPH (2,2-diphenyl-1-picryl-hydrazyl) and ferric reducing power methods. In in vitro experiment, human blood samples were treated with OLA at various concentrations (0.25-20 μM) for 3 h and then were exposed to X-ray at a dose of 150 cGy. The genotoxicity was assessed in binucleated human lymphocytes with micronuclei assay. The apoptotic lymphocytes were assessed by flow cytometry in OLA treated and/or irradiated lymphocytes. OLA exhibited free radical scavenging and reducing power activities more than ascorbic acid. The results showed that the lymphocytes treated with OLA and later exposed to IR presented lower frequencies of micronuclei and apoptosis compared to the control sample which was irradiated and not treated to OLA. The maximum radioprotection was observed at 20 μM of OLA with 83% of efficacy. The present study suggested the protective role for OLA in protection radiation-induced genetic damage and apoptosis induced by ionizing irradiation in human normal cells.

Ascorbyl stearate stimulates cell death by oxidative stress-mediated apoptosis and autophagy in HeLa cervical cancer cell line in vitro

In this study, Asc-s was evaluated for anti-cancer effect using cervical cancer cells (HeLa). Results determine that Asc-s treatment-induced dose-dependent inhibition of proliferation of HeLa cells and induced apoptosis. Flow-cytometry analysis shows Asc-s treatment-induced accumulation of cells at sub-G0/G1 stage of cell cycle and induced apoptosis as confirmed by DAPI, propodium iodide, and acridine staining in HeLa cells. Asc-s entered the cells and metabolized to ascorbate and stearate moieties, increased membrane permeability, and decreased membrane fluidity in HeLa cells. Asc-s treatment-induced dose-dependent increase in autophagy protein LC3-II, mRNA levels and decreased Nrf-2 levels in HeLa cells. It is hypothesized that both ascorbyl radical and stearoyl moieties of Asc-s induced cytotoxicity by generating reactive oxygen species (ROS) and modulating membrane fluidity/permeability leading to apoptosis/autophagy of HeLa cells. Thus, our findings demonstrate that Asc-s as anti-proliferative and apoptosis inducing compound in cervical cancer cells.

Radioprotective Properties of Pterocarpus santalinus Chloroform Extract in Murine Splenic Lymphocytes and Possible Mechanism

Background: Pterocarpus santalinus popularly known as Red Sanders is an endemic species confined to Southern part of Eastern Ghats of India especially in Andhra Pradesh and has high demand for its economical importance for its use in treatment of human ailments. Materials and Methods: In the present study, the authors have examined the presence of various phytochemicals in the chloroform extract of P. santalinus heartwood (PSCE, Pterocarpus santalinus chloroform extract) by qualitative and quantitative assays. PSCE was further used to evaluate its antioxidant and metal reducing capacity. Radioprotective property was also evaluated in various subcellular and cellular model systems. Results: The phytochemical screening study showed that the extract was positive for carbohydrates, cardiac glycosides, flavonoids, phenols, tannins, saponins, and terpenoids and was negative for alkaloids, steroids, and phlobatannins. Contents of total phenol, total flavonoids, total anthocyanin, and total tannin in the PSCE are 404 μg/mg in terms of gallic acid equivalents, 22.6 μg/mg in terms of quercetin equivalents, 0.066 mg in terms of cyanidin-3-glucoside (cyn-3-glu) equivalents, and 12.477 g/L, respectively. This extract exhibited significant radical scavenging activity against model free radical 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radical (ABTS•+), 1,1-diphenyl picrylhydrazyl, and biologically important nitric oxide. It has significant metal reducing capacity as monitored by ferric and molybdenum reduction assay. PSCE showed a concentration dependent radioprotection to plasmid pBR322 DNA and lipids of the mitochondrial membranes. Their study also showed that PSCE protected splenic lymphocytes against radiation induced cell death, DNA double strand breaks, and lipid peroxidation as monitored by propidium iodide staining, γ-H2AX assay, neutral comet assay, and TBARS assay, respectively. Addition of PSCE to lymphocytes scavenged radiation derived reactive oxygen species, restored loss of thiol content, and inhibited cellular apoptosis. Conclusions: PSCE possesses high antioxidant activity and exhibited very good radioprotective property in cell free and cellular model systems.

Discovery and characterization of miRNAs in mouse thymus responses to ionizing radiation by deep sequencing

To investigate the potential regulatory roles of microRNA (miRNA) in mouse response to ionizing radiation (IR)-induced thymus injury, miRNA expression profiles of mouse thymus with or without IR were analyzed using deep sequencing technology. Potential target candidates of the identified miRNA were predicted using RNAhybrid and miRanda. Differently expressed miRNA targets functional annotation and pathways were noted using Swiss-Prot, Gene Ontology (GO), Clusters of Orthologous Groups (COG), Kyoto Encyclopedia of Genes and Genomes (KEGG) and non-redundant (NR) databases. In this study, there were 112 differently expressed miRNAs identified, including 45 known mature and 67 novel miRNAs, which meanwhile contained 77 up-regulated and 35 down-regulated miRNAs. The results of quantitative RT-polymerase chain reaction (qRT-PCR) verification were in agreement with the sequencing analysis. And the target genes of miRNA were annotated. These results revealed the differences of miRNA expression, further extended the biological knowledge and greatly facilitated future studies on the function of miRNA in IR-induced thymus injury.

MiRNA expression profile of ionizing radiation-induced liver injury in mouse using deep sequencing

In order to investigate the potential regulatory roles of microRNAs (miRNAs) in mouse response to ionizing radiation (IR), the small RNA libraries from liver tissues of mice with or without ionizing radiation (IR) were sequenced by high-throughput deep sequencing technology. A total of 270 miRNAs including 212 known and 58 potentially novel miRNAs were identified. Within these miRNAs, there were 48 miRNAs that were differentially expressed, including 27 known and 21 novel miRNAs. The results of quantitative RT-polymerase chain reaction (qRT-PCR) were in consistent with the sequencing analysis. Target gene prediction, function annotation, and pathway of the identified miRNAs were analyzed using RNAhybrid, miRanda software and Swiss-Prot, Gene Ontology (GO), Clusters of Orthologous Groups (COG), Kyoto Encyclopedia of Genes, and Genomes (KEGG) and non-redundant (NR) databases. These results should be useful to investigate the biological function of miRNAs under IR-induced liver injury.

Mutual modulation between norepinephrine and nitric oxide in haemocytes during the mollusc immune response

Nitric oxide (NO) is one of the most important immune molecules in innate immunity of invertebrates, and it can be regulated by norepinephrine in ascidian haemocytes. In the present study, the mutual modulation and underlying mechanism between norepinephrine and NO were explored in haemocytes of the scallop Chlamys farreri. After lipopolysaccharide stimulation, NO production increased to a significant level at 24 h, and norepinephrine concentration rose to remarkable levels at 3 h and 12~48 h. A significant decrease of NO production was observed in the haemocytes concomitantly stimulated with lipopolysaccharide and α-adrenoceptor agonist, while a dramatic increase of NO production was observed in the haemocytes incubated with lipopolysaccharide and β-adrenoceptor agonist. Meanwhile, the concentration of cyclic adenosine monophosphate (cAMP) decreased significantly in the haemocytes treated by lipopolysaccharide and α/β-adrenoceptor agonist, while the content of Ca(2+) was elevated in those triggered by lipopolysaccharide and β-adrenoceptor agonist. When the haemocytes was incubated with NO donor, norepinephrine concentration was significantly enhanced during 1~24 h. Collectively, these results suggested that norepinephrine exerted varied effects on NO production at different immune stages via a novel α/β-adrenoceptor-cAMP/Ca(2+) regulatory pattern, and NO might have a feedback effect on the synthesis of norepinephrine in the scallop haemocytes.

Interferon-Beta combined with interleukin-2 restores human natural cytotoxicity impaired in vitro by ionizing radiations

It is well known that ionizing radiations induce a marked downregulation of antigen-dependent and natural immunity for a prolonged period of time. This is due, at least in part, to radiation-induced apoptosis of different lymphocyte subpopulations, including natural killer (NK) cells. Aim of this study was to investigate the capability of Beta Interferon (β-IFN) and Interleukin-2 (IL2), alone or in combination, to restore the functional activity of the natural immune system. Mononuclear cells (MNCs) obtained from intact or in vitro irradiated human peripheral blood were treated in vitro with β-IFN immediately before or at the end of the 4-day treatment with IL2. Time-course analysis was performed on the NK activity, the total number and the apoptotic fraction of CD16+ and CD56+ cells, the 2 main NK effector cell subpopulations. The results indicate that radiation-induced impairment of natural cytotoxicity of MNC could be successfully antagonized by the β-IFN+IL2 combination, mainly when exposure to β-IFN preceded IL2 treatment. This radioprotective effect is paralleled by lower levels of radiation-induced apoptosis and increased expression of the antiapoptotic Bcl-2 protein. Since natural immunity can play a significant role in antitumor host's resistance, these results could provide the rational basis for a cytokine-based pharmacological strategy able to restore immune responsiveness and to afford possible therapeutic benefits in cancer patients undergoing radiotherapy.

The Roles of Radiotherapy and Immunotherapy for the Treatment of Lymphoma

Lymphoma is rising in incidence and there is a continued need for new and novel therapeutic options. Lymphomas are extremely radiosensitive, but the majority of patients are not candidates for involved field radiation therapy. An intact immune system has a critical role in suppressing lymphomagenesis. Here we discuss the contribution of various components of the immune system in suppressing the development of lymphoma, as elucidated from mouse models. We review the nature of the immune response to lymphoma in non-immunocompromised patients. Finally, we discuss the potential role of immunomodulation, in concert with radiation therapy, as a component of future therapeutic strategies for lymphoma.

The immunomodulation of inducible nitric oxide in scallop Chlamys farreri

Nitric oxide (NO) is an important signalling molecule which plays an indispensable role in immunity of all vertebrates and invertebrates. In the present study, the immunomodulation of inducible NO in scallop Chlamys farreri was examined by monitoring the alterations of haemocyte behaviours and related immune molecules in response to the stimulations of LPS and/or with S-Methylisothiourea Sulphate (SMT), an inhibitor of inducible NO synthase (NOS). The total activity of NOS and NO concentration in the haemolymph of scallop C. farreri increased significantly at 3, 6 and 12 h after LPS stimulation respectively, whereas their increases were fully repressed when scallops were treated in the collaborating of LPS and SMT. Meanwhile, some cellular and humoral immune parameters were determined after the stimulation of LPS and SMT to investigate the role of inducible NO in innate immunity of scallop. After LPS stimulation, the highest levels of haemocytes apoptosis and phagocytosis were observed at 24 h (38.5 ± 2.5%, P < 0.01) and 12 h (38.6 ± 0.2%, P < 0.01), respectively, and the reactive oxygen species (ROS) level (5.88 ± 0.90%, P < 0.01) of haemocytes and anti-bacterial activity of haemolymph (10.0 ± 2.2%, P < 0.01) all elevated dramatically at 12 h. Although the activity of lysozyme and phenoloxidase (PO) in haemolymph both declined at 48 h (93.0 ± 6.3 U mgprot(-1), 0.40 ± 0.06 U mgprot(-1), P < 0.01), superoxide dismutase (SOD) activity and GSH concentration both increased to the highest level at 24 h post treatment (99.2 ± 8.1 U mgprot(-1), 93.0 ± 6.3 nmol mgprot(-1), P < 0.01). After the collaborating treatment of LPS and SMT, the apoptosis index increased much higher from 48 h, while the increase of haemocytes phagocytosis, ROS level and haemolymph anti-bacteria activities were suppressed completely at 12 h. The declines of lysozyme and PO activity in haemolymph were reversed at 48 h, and the rise of SOD activity and GSH concentration started earlier from 3 h. These results indicated clearly that NO could participate in the scallop immunity and play a crucial role in the modulation of immune response including haemocytes apoptosis and phagocytosis, anti-bacterial activity and redox homeostasis in the haemolymph of scallop.

Bilirubin augments radiation injury and leads to increased infection and mortality in mice: molecular mechanisms

Our earlier results demonstrated that clinically relevant concentrations of unconjugated bilirubin (UCB) possessed immunotoxic effects. Whole-body irradiation (WBI) with 1 to 6 Gy leads to acute radiation syndrome, immunosuppression, and makes the host susceptible to infection. Since hyperbilirubinemia has been shown to be associated with several types of cancer, the present studies were undertaken to evaluate the radiomodifying effects of UCB in radiation-exposed mice having elevated levels of UCB. Pretreatment of splenic lymphocytes with UCB (1-50 μM at UCB/BSA ratio <1) augmented radiation-induced DNA strand breaks, MMP loss, calcium release, and apoptosis. Combination treatment of mice with UCB (50mg/kg bw) followed by WBI (2 Gy) 0.5h later, resulted in significantly increased splenic atrophy, bone marrow aplasia, decreased counts of peritoneal exudate cells, and different splenocyte subsets such as CD3+ T, CD4+ T, CD8+ T, CD19+ B, and CD14+ macrophages as compared to either UCB or WBI treatment. Hematological studies showed that WBI-induced lymphopenia, thrombocytopenia, and neutropenia were further aggravated in the combination treatment group. UCB pretreatment of mice potentiated WBI-induced apoptosis and decreased WBI-induced loss of functional response of various immune cells leading to augmentation of immunosuppression and infection susceptibility caused by WBI. In an acute bacterial peritonitis model, UCB pretreatment of mice significantly increased WBI-induced proinflammatory cytokines, nitric oxide, and peritoneal bacterial load resulting in increased infection and death. Studies using the pharmacological inhibitor of p38MAPK demonstrated the involvement of p38MAPK activation in the inflammatory cascade of peritonitis. These findings should prove useful in understanding the potential risk to hyperbilirubinemic patients during radiotherapy and victims of acute radiation exposure in the course of radiation accidents.

α-Tocopherol succinate protects mice against radiation-induced gastrointestinal injury

The purpose of this study was to elucidate the role of α-tocopherol succinate (α-TS) in protecting mice from gastrointestinal syndrome induced by total-body irradiation. CD2F1 mice were injected subcutaneously with 400 mg/kg of α-TS and exposed to different doses of (60)Co γ radiation, and 30-day survival was monitored. Jejunum sections were analyzed for crypts and villi, PUMA (p53 upregulated modulator of apoptosis), and apoptosis (terminal deoxynucleotidyl transferase dUTP nick end labeling - TUNEL). The crypt regeneration in irradiated mice was evaluated by 5-bromo-2-deoxyuridine (BrdU). Bacterial translocation from gut to heart, spleen and liver in α-TS-treated and irradiated mice was evaluated by bacterial culture on sheep blood agar, colistin-nalidixic acid, and xylose-lysine-desoxycholate medium. Our results demonstrate that α-TS enhanced survival in a significant number of mice irradiated with 9.5, 10, 11 and 11.5 Gy (60)Co γ radiation when administered 24 h before radiation exposure. α-TS also protected the intestinal tissue of irradiated mice in terms of crypt and villus number, villus length and mitotic figures. TS treatment decreased the number of TUNEL- and PUMA-positive cells and increased the number of BrdU-positive cells in jejunum compared to vehicle-treated mice. Further, α-TS inhibited gut bacterial translocation to the heart, spleen and liver in irradiated mice. Our data suggest that α-TS protects mice from radiation-induced gastrointestinal damage by inhibiting apoptosis, promoting regeneration of crypt cells, and inhibiting translocation of gut bacteria.

Immunomodulatory and immunotoxic effects of bilirubin: molecular mechanisms

The immunomodulatory and immunotoxic effects of purified UCB have not been evaluated previously at clinically relevant UCB concentrations and UCB:BSA ratios. To delineate the molecular mechanism of UCB-induced immunomodulation, immune cells were exposed to clinically relevant concentrations of UCB. It inhibited LPS-induced B cell proliferation and cytokine production from splenic macrophages. UCB (≥25 μM) was toxic to unfractionated splenocytes, splenic T cells, B cells, macrophages, LPS-stimulated CD19(+) B cells, human PBMCs, and RBCs. Purified UCB also was found to be toxic to splenocytes and human PBMCs. UCB induced necrosis and apoptosis in splenocytes. UCB activated the extrinsic and intrinsic pathways of apoptosis, as reflected by the markers, such as CD95, caspase-8, Bax, MMP, cytoplasmic Ca(+2), caspase-3, and DNA fragmentation. UCB depleted GSH and activated p38MAPK. NAC, caspase inhibitors, and p38MAPK inhibitor attenuated the UCB-induced apoptosis. In vivo administration of ≥25 mg/kbw UCB induced atrophy of spleen, depletion of bone marrow cells, and leukopenia and decreased lymphocyte count and the T and B cell response to mitogens. UCB administration to mice led to induction of oxidative stress, activation of p38MAPK, and cell death in splenocytes. These parameters were attenuated by the injection of NAC and the p38MAPK inhibitor. Our results demonstrate for the first time that clinically relevant concentrations of UCB induce apoptosis and necrosis in immune cells by depleting cellular GSH. These findings should prove useful in understanding the immunosuppression associated with hyperbilirubinemia.