Sedum kamtschaticum Exerts Hypnotic Effects via the Adenosine A2A Receptor in Mice.

Insomnia is a common sleep disorder with significant societal and economic impacts. Current pharmacotherapies for insomnia are often accompanied by side effects, necessitating the development of new therapeutic drugs. In this study, the hypnotic effects and mechanisms of Sedum kamtschaticum 30% ethanol extract (ESK) and one of its active compounds, myricitrin, were investigated using pentobarbital-induced sleep experiments, immunohistochemistry (IHC), receptor binding assays, and enzyme-linked immunosorbent assay (ELISA). The pentobarbital-induced sleep experiments revealed that ESK and myricitrin reduced sleep latency and prolonged total sleep time in a dose-dependent manner. Based on c-Fos immunostaining, ESK, and myricitrin enhanced the GABAergic neural activity in sleep-promoting ventrolateral preoptic nucleus (VLPO) GABAergic. By measuring the level of GABA released from VLPO GABAergic neurons, ESK and myricitrin were found to increase GABA release in the hypothalamus. These effects were significantly inhibited by SCH. Moreover, ESK exhibited a concentration-dependent binding affinity for the adenosine A2A receptors (A2AR). In conclusion, ESK and myricitrin have hypnotic effects, and their underlying mechanisms may be related to the activation of A2AR.

Low dose radiation regulates BRAF-induced thyroid cellular dysfunction and transformation.

BACKGROUND: The existence of differentiated thyroid cells is critical to respond radioactive iodide treatment strategy in thyroid cancer, and loss of the differentiated phenotype is a trademark of iodide-refractive thyroid disease. While high-dose therapy has been beneficial to several cancer patients, many studies have indicated this clinical benefit was limited to patients having BRAF mutation. BRAF-targeted paired box gene-8 (PAX8), a thyroid-specific transcription factor, generally dysregulated in BRAF-mutated thyroid cancer. METHODS: In this study, thyroid iodine-metabolizing gene levels were detected in BRAF-transformed thyroid cells after low and high dose of ionizing radiation. Also, an mRNA-targeted approach was used to figure out the underlying mechanism of low (0.01Gyx10 or 0.1Gy) and high (2Gy) radiation function on thyroid cancer cells after BRAFV600E mutation. RESULTS: Low dose radiation (LDR)-induced PAX8 upregulation restores not only BRAF-suppressive sodium/iodide symporter (NIS) expression, one of the major protein necessary for iodine uptake in healthy thyroid, on plasma membrane but also regulate other thyroid metabolizing genes levels. Importantly, LDR-induced PAX8 results in decreased cellular transformation in BRAF-mutated thyroid cells. CONCLUSION: The present findings provide evidence that LDR-induced PAX8 acts as an important regulator for suppression of thyroid carcinogenesis through novel STAT3/miR-330-5p pathway in thyroid cancers.

Pharmacology of natural radioprotectors.

Radiotherapy is one of the most efficient ways to treat cancer. However, deleterious effects, such as acute and chronic toxicities that reduce the quality of life, may result. Naturally occurring compounds have been shown to be non-toxic over wide dose ranges and are inexpensive and effective. Additionally, pharmacological strategies have been developed that use radioprotectors to inhibit radiation-induced toxicities. Currently available radioprotectors have several limitations, including toxicity. In this review, we present the mechanisms of proven radioprotectors, ranging from free radical scavenging (the best-known mechanism of radioprotection) to molecular-based radioprotection (e.g., upregulating expression of heat shock proteins). Finally, we discuss naturally occurring compounds with radioprotective properties in the context of these mechanisms.

Metformin Alleviates Radiation-Induced Skin Fibrosis via the Downregulation of FOXO3.

BACKGROUND/AIMS: Radiation-induced skin fibrosis is a common side effect of clinical radiotherapy. Our previous next-generation sequencing (NGS) study demonstrated the reduced expression of the regulatory α subunit of phosphatidylinositol 3-kinase (PIK3r1) in irradiated murine skin. Metformin has been reported to target the PIK3-FOXO3 pathway. In this study, we investigated the effects of metformin on radiation-induced skin fibrosis. METHODS: Metformin was orally administered to irradiated mice. Skin fibrosis was analyzed by staining with H&E and Masson's trichrome stain. The levels of cytokines and chemokines associated with fibrosis were analyzed by immunohistochemistry and quantitative RT-PCR. The roles of PIK3rl and FOXO3 in radiation-induced skin fibrosis were studied by overexpressing PIK3rl and transfecting FOXO3 siRNA in NIH3T3 cells and mouse-derived dermal fibroblasts (MDF). RESULTS: The oral administration of metformin significantly reduced radiation-induced skin thickening and collagen accumulation and significantly reduced the radiation-induced expression of FOXO3 in murine skin. Additionally, the overexpression of PIK3r1 reduced the radiation-induced expression of FOXO3, while FOXO3 silencing decreased the radiation-induced expression of TGFß in vitro. CONCLUSIONS: The results indicated that metformin suppresses radiation-induced skin injuries by modulating the expression of FOXO3 through PIK3r1. Collectively, the data obtained in this study suggested that metformin could be a potent therapeutic agent for alleviating radiation-induced skin fibrosis.

Tyndallized Lactobacillus plantarum HY7712 Restores Whole-Body γ-Irradiation-Impaired Th Cell Differentiation in Mice.

In the present study, we investigated the effect of tyndallized HY7712 (tHY7712) on the expression of Th cell specific transcription factors and cytokines in whole-body γ-irradiated mice. Oral administration of tHY7712 strongly recovered the γ-irradiation-suppressed expression of helper T (Th) cell- and regulatory T cell-related transcription factors and cytokines, such as T-bet, Foxp3, IFN-γ, TNF-α, and IL-10, and suppressed Th2 cell-associated transcription factor and cytokine GATA3 and IL-5, respectively. Furthermore, compared with the control, tHY7712 treatment also restored γ-irradiation-impaired natural killer and cytotoxic T cell activities against YAC-1 tumor cells to 97.8% and 98.6%, respectively.

Estimation of low-dose radiation-responsive proteins in the absence of genomic instability in normal human fibroblast cells.

PURPOSE: Low-dose radiation has various biological effects such as adaptive responses, low-dose hypersensitivity, as well as beneficial effects. However, little is known about the particular proteins involved in these effects. Here, we sought to identify low-dose radiation-responsive phosphoproteins in normal fibroblast cells. MATERIALS AND METHODS: We assessed genomic instability and proliferation of fibroblast cells after γ-irradiation by γ-H2AX foci and micronucleus formation analyses and BrdU incorporation assay, respectively. We screened fibroblast cells 8 h after low-dose (0.05 Gy) γ-irradiation using Phospho Explorer Antibody Microarray and validated two differentially expressed phosphoproteins using Western blotting. RESULTS: Cell proliferation proceeded normally in the absence of genomic instability after low-dose γ-irradiation. Phospho antibody microarray analysis and Western blotting revealed increased expression of two phosphoproteins, phospho-NFκB (Ser536) and phospho-P70S6K (Ser418), 8 h after low-dose radiation. CONCLUSIONS: Our findings suggest that low-dose radiation of normal fibroblast cells activates the expression of phospho-NFκB (Ser536) and phospho-P70S6K (Ser418) in the absence of genomic instability. Therefore, these proteins may be involved in DNA damage repair processes.

Phosphoprotein profiles of candidate markers for early cellular responses to low-dose γ-radiation in normal human fibroblast cells.

Ionizing radiation causes biological damage that leads to severe health effects. However, the effects and subsequent health implications caused by exposure to low-dose radiation are unclear. The objective of this study was to determine phosphoprotein profiles in normal human fibroblast cell lines in response to low-dose and high-dose γ-radiation. We examined the cellular response in MRC-5 cells 0.5 h after exposure to 0.05 or 2 Gy. Using 1318 antibodies by antibody array, we observed ≥1.3-fold increases in a number of identified phosphoproteins in cells subjected to low-dose (0.05 Gy) and high-dose (2 Gy) radiation, suggesting that both radiation levels stimulate distinct signaling pathways. Low-dose radiation induced nucleic acid-binding transcription factor activity, developmental processes, and multicellular organismal processes. By contrast, high-dose radiation stimulated apoptotic processes, cell adhesion and regulation, and cellular organization and biogenesis. We found that phospho-BTK (Tyr550) and phospho-Gab2 (Tyr643) protein levels at 0.5 h after treatment were higher in cells subjected to low-dose radiation than in cells treated with high-dose radiation. We also determined that the phosphorylation of BTK and Gab2 in response to ionizing radiation was regulated in a dose-dependent manner in MRC-5 and NHDF cells. Our study provides new insights into the biological responses to low-dose γ-radiation and identifies potential candidate markers for monitoring exposure to low-dose ionizing radiation.

Gene expression profiling in undifferentiated thyroid carcinoma induced by high-dose radiation.

Published gene expression studies for radiation-induced thyroid carcinogenesis have used various methodologies. In this study, we identified differential gene expression in a human thyroid epithelial cell line after exposure to high-dose γ-radiation. HTori-3 cells were exposed to 5 or 10 Gy of ionizing radiation using two dose rates (high-dose rate: 4.68 Gy/min, and low-dose rate: 40 mGy/h) and then implanted into the backs of BALB/c nude mice after 4 (10 Gy) or 5 weeks (5 Gy). Decreases in cell viability, increases in giant cell frequency, anchorage-independent growth in vitro, and tumorigenicity in vivo were observed. Particularly, the cells irradiated with 5 Gy at the high-dose rate or 10 Gy at the low-dose rate demonstrated more prominent tumorigenicity. Gene expression profiling was analyzed via microarray. Numerous genes that were significantly altered by a fold-change of >50% following irradiation were identified in each group. Gene expression analysis identified six commonly misregulated genes, including CRYAB, IL-18, ZNF845, CYP24A1, OR4N4 and VN1R4, at all doses. These genes involve apoptosis, the immune response, regulation of transcription, and receptor signaling pathways. Overall, the altered genes in high-dose rate (HDR) 5 Gy and low-dose rate (LDR) 10 Gy were more than those of LDR 5 Gy and HDR 10 Gy. Thus, we investigated genes associated with aggressive tumor development using the two dosage treatments. In this study, the identified gene expression profiles reflect the molecular response following high doses of external radiation exposure and may provide helpful information about radiation-induced thyroid tumors in the high-dose range.

Strong Correlation among Three Biodosimetry Techniques Following Exposures to Ionizing Radiation.

Three in vitro dose calibration curves for biodosimetry such as dicentric chromosome assay, fluorescence in situ hybridization (FISH) assay for translocation, and micronuclei (MNs) in binucleated cell assay were established after exposure to ionizing radiation. Peripheral blood lymphocyte samples obtained from healthy donors were irradiated with 60Co source at a dose rate of 0.5 Gy/min to doses of 0.1-6 Gy. The results from three in vitro dose calibration curves for biodosimetry were analyzed to understand the relationship among biodosimetry assay techniques. Our comparison demonstrates that there is a very strong positive correlation among the dicentric assay, FISH, and MNs analysis, and these three biodosimetry assays strongly support the in vitro dose reconstruction and the emergency preparedness of public or occupational radiation overexposure.

The Inhibitory Effects of Low-Dose Ionizing Radiation in IgE-Mediated Allergic Responses.

Ionizing radiation has different biological effects according to dose and dose rate. In particular, the biological effect of low-dose radiation is unclear. Low-dose whole-body gamma irradiation activates immune responses in several ways. However, the effects and mechanism of low-dose radiation on allergic responses remain poorly understood. Previously, we reported that low-dose ionizing radiation inhibits mediator release in IgE-mediated RBL-2H3 mast cell activation. In this study, to have any physiological relevance, we investigated whether low-dose radiation inhibits allergic responses in activated human mast cells (HMC-1(5C6) and LAD2 cells), mouse models of passive cutaneous anaphylaxis and the late-phase cutaneous response. High-dose radiation induced cell death, but low-dose ionizing radiation of <0.5 Gy did not induce mast cell death. Low-dose ionizing radiation that did not induce cell death significantly suppressed mediator release from human mast cells (HMC-1(5C6) and LAD2 cells) that were activated by antigen-antibody reaction. To determine the inhibitory mechanism of mediator released by low-dose ionizing radiation, we examined the phosphorylation of intracellular signaling molecules such as Lyn, Syk, phospholipase Cγ, and protein kinase C, as well as the intracellular free Ca2+ concentration ([Ca2+]i). The phosphorylation of signaling molecules and [Ca2+]i following stimulation of FcεRI receptors was inhibited by low dose ionizing radiation. In agreement with its in vitro effect, ionizing radiation also significantly inhibited inflammatory cells infiltration, cytokine mRNA expression (TNF-α, IL-4, IL-13), and symptoms of passive cutaneous anaphylaxis reaction and the late-phase cutaneous response in anti-dinitrophenyl IgE-sensitized mice. These results indicate that ionizing radiation inhibits both mast cell-mediated immediate- and delayed-type allergic reactions in vivo and in vitro.

Sam68 is cleaved by caspases under apoptotic cell death induced by ionizing radiation.

The RNA-binding protein Sam68, a mitotic substrate of tyrosine kinases, has been reported to participate in the cell cycle, apoptosis, and signaling. In particular, overexpression of Sam68 protein is known to suppress cell growth and cell cycle progression in NIH3T3 cells. Although Sam68 is involved in many cellular activities, the function of Sam68, especially in response to apoptotic stimulation, is not well understood. In this study, we found that Sam68 protein is cleaved in immune cells undergoing apoptosis induced by γ-radiation. Moreover, we found that Sam68 cleavage was induced by apoptotic stimuli containing γ-radiation in a caspase-dependent manner. In particular, we showed that activated casepase-3, 7, 8 and 9 can directly cleave Sam68 protein through in vitro protease cleavage assay. Finally, we found that the knockdown of Sam68 attenuated γ-radiation-induced cell death and growth suppression. Conclusively, the cleavage of Sam68 is a new indicator for the cell damaging effects of ionizing radiation.

Lactobacillus plantarum HY7712 protects against the impairment of NK-cell activity caused by whole-body γ-irradiation in mice.

While searching for lactic acid bacteria that can restore aging-impaired immune responses, we isolated the Toll-like receptor (TLR) 2/NF-kappaB-activating strain Lactobacillus plantarum HY7712 from kimchi and investigated its immunomodulating effect in whole-body γ-irradiated mice. Exposure to HY7712 strongly activated NF-kappaB signaling in RAW264.7 cells, but inhibited lipopolysaccharide-stimulated NF-kappaB activation. Moreover, HY7712 protected against the downregulation of interferon (IFN)-γ and upregulation of interleukin (IL)-13 caused by γ-irradiation in mice. In mice, γ-irradiation impaired NK-cell activity against YAC-1 tumor cells, but following HY7712 exposure, the activity of NK cells was restored to 91.5% of the level measured in control mice (p < 0.05). These findings suggest that HY7712 activates the TLR2/NF-kappaB signaling pathway and protects against the impairment of NK-cell activity caused by γ-irradiation or aging.

Chronic low-dose radiation inhibits the cells death by cytotoxic high-dose radiation increasing the level of AKT and acinus proteins via NF-κB activation.

PURPOSE: This study explored the effects of low-dose and low-dose-rate irradiation in human lung fibroblast CCD-18Lu cells and examined the role of AKT (protein kinase B, PKB) in cellular responses. MATERIALS AND METHODS: We examined cell survival after chronic low-dose irradiation (0.01 Gy or 0.05 Gy) with challenging high-dose (2 or 10 Gy) irradiation. We examined the effect of AKT activation on cell survival after chronic low-dose radiation using transduced cells with retroviral vector expressing constitutively active AKT (CA-AKT). RESULTS: Chronic low-dose priming irradiation increased cells viability against the challenging high-dose irradiation. Irradiation at 0.05 Gy increased cellular levels of AKT and acinus long form (L) and short form (S). The chronic low-dose radiation promoted cells proliferation in the exogenously expressed CA-AKT cells. It also increased nuclear factor-kappa B (NF-κB) activity in a biphasic induction pattern. Suppression of NF-κB activation by mutant form of inhibitor of kappa B alpha (IκBαM) antagonized the radiation-induced expression of AKT and acinus L and S. CONCLUSIONS: Chronic low-dose radiation increases the levels of AKT and acinus proteins via NF-κB activation, and the NF-κB/AKT pathway responding to chronic low-dose irradiation plays an important role in the radiation adaptive response.

TOPORS modulates H2AX discriminating genotoxic stresses.

H2AX plays an important role in chromatin reorganization implicated in DNA repair and apoptosis under various DNA damaging conditions. In this study, the interaction between TOPORS (topoisomerase I-binding protein) and H2AX was verified using mammalian cell extracts exposed to diverse DNA damaging stresses such as ionizing radiation, doxorubicin, camptothecin, and hydrogen peroxide. In vitro assays for ubiquitination revealed that TOPORS functions as a novel E3 ligase for H2AX ubiquitination. TOPORS was found to be dissociated from H2AX proteins when cells were exposed to oxidative stress, but not replication-inducing DNA damaging stress. The protein stability of H2AX was decreased when TOPORS was ectopically expressed in cells, and oxidative stresses such as hydrogen peroxide and ionizing radiation induced recovery of the H2AX protein level. Therefore, these biochemical data suggest that TOPORS plays a key role in the turnover of H2AX protein, discriminating the type of DNA damaging stress.

The effects of low-dose ionizing radiation in the activated rat basophilic leukemia (RBL-2H3) mast cells.

Mast cells play important roles in many biological responses, such as those during allergic diseases and inflammatory disorders. Although laser and UV irradiation have immunosuppressive effects on inflammatory diseases by suppressing mast cells, little is known about the effects of γ-ionizing radiation on mast cells. In this study, we investigated the effects of γ-ionizing radiation on RBL-2H3 cells, a convenient model system for studying regulated secretion by mast cells. Low-dose radiation (<0.1 gray (Gy)) did not induce cell death, but high-dose radiation (>0.5 Gy) induced apoptosis. Low-dose ionizing radiation significantly suppressed the release of mediators (histamine, ß-hexosaminidase, IL-4, and tumor necrosis factor-α) from immunoglobulin E (IgE)-sensitized RBL-2H3 cells. To determine the mechanism of mediator release inhibition by ionizing radiation, we examined the activation of intracellular signaling molecules such as Lyn, Syk, phospholipase Cγ, PKCs, and MAPK, and intracellular free calcium concentrations ([Ca(2+)](i)). The phosphorylation of signaling molecules following stimulation of high-affinity IgE receptor I (FcεRI) was specifically inhibited by low-dose ionizing radiation (0.01 Gy). These results were due to the suppression of FcεRI expression by the low-dose ionizing radiation. Therefore, low-dose ionizing radiation (0.01 Gy) may function as a novel inhibitor of mast cell activation.

Low-dose radiation induces Drosophila innate immunity through Toll pathway activation.

Numerous studies report that exposing certain organisms to low-dose radiation induces beneficial effects on lifespan, tumorigenesis, and immunity. By analyzing survival after bacterial infection and antimicrobial peptide gene expression in irradiated flies, we demonstrate that low-dose irradiation of Drosophila enhances innate immunity. Low-dose irradiation of flies significantly increased resistance against gram-positive and gram-negative bacterial infections, as well as expression of several antimicrobial peptide genes. Additionally, low-dose irradiation also resulted in a specific increase in expression of key proteins of the Toll signaling pathway and phosphorylated forms of p38 and JNK. These results indicate that innate immunity is activated after low-dose irradiation through Toll signaling pathway in Drosophila.

Psoralidin, a dual inhibitor of COX-2 and 5-LOX, regulates ionizing radiation (IR)-induced pulmonary inflammation.

Radiotherapy is the most significant non-surgical cure for the elimination of tumor, however it is restricted by two major problems: radioresistance and normal tissue damage. Efficiency improvement on radiotherapy is demanded to achieve cancer treatment. We focused on radiation-induced normal cell damage, and are concerned about inflammation reported to act as a main limiting factor in the radiotherapy. Psoralidin, a coumestan derivative isolated from the seed of Psoralea corylifolia, has been studied for anti-cancer and anti-bacterial properties. However, little is known regarding its effects on IR-induced pulmonary inflammation. The aim of this study is to investigate mechanisms of IR-induced inflammation and to examine therapeutic mechanisms of psoralidin in human normal lung fibroblasts and mice. Here, we demonstrated that IR-induced ROS activated cyclooxygenases-2 (COX-2) and 5-lipoxygenase (5-LOX) pathway in HFL-1 and MRC-5 cells. Psoralidin inhibited the IR-induced COX-2 expression and PGE(2) production through regulation of PI3K/Akt and NF-κB pathway. Also, psoralidin blocked IR-induced LTB(4) production, and it was due to direct interaction of psoralidin and 5-lipoxygenase activating protein (FLAP) in 5-LOX pathway. IR-induced fibroblast migration was notably attenuated in the presence of psoralidin. Moreover, in vivo results from mouse lung indicate that psoralidin suppresses IR-induced expression of pro-inflammatory cytokines (TNF-α, TGF-ß, IL-6 and IL-1 α/ß) and ICAM-1. Taken together, our findings reveal a regulatory mechanism of IR-induced pulmonary inflammation in human normal lung fibroblast and mice, and suggest that psoralidin may be useful as a potential lead compound for development of a better radiopreventive agent against radiation-induced normal tissue injury.

Ret finger protein 2 enhances ionizing radiation-induced apoptosis via degradation of AKT and MDM2.

Ret finger protein 2 (RFP2), a gene frequently deleted in multiple tumor types, encodes a protein with a RING finger, B-box, and coiled-coil domain that belongs to the RBCC/TRIM protein family. Although RBCC proteins are involved in diverse cellular processes such as apoptosis, proliferation, differentiation, and transcriptional regulation, the biological function of RFP2 has not been well defined. Here, we demonstrate that overexpression of RFP2 in cells induced apoptosis through proteasomal degradation of MDM2 and AKT. The expression of RFP2, which possesses RING domain-dependent E3 ubiquitin ligase activity, was increased by ionizing radiation dose- and time-dependently, and RFP2 overexpression induced cell death with increased expression of apoptotic molecules (p53, p21, and Bax). These results depended on the E3 ubiquitin ligase activity of RFP2 because mutant RFP2, which contains a mutated RING domain, failed to drive apoptosis compared with wild-type RFP2. We observed that RFP2 formed a complex with MDM2, a negative regulator of the p53 tumor suppressor, and AKT, a regulator of apoptosis inhibition at the cellular level. Additionally, we found that the interaction of RFP2 with MDM2 and AKT resulted in ubiquitination and proteasomal degradation of MDM2 and AKT in vivo and in vitro. Thus, these data suggest that irradiation causes RFP2 overexpression, which enhances ionizing radiation-induced apoptosis by increasing p53 stability and decreasing AKT kinase activity through MDM2 and AKT degradation.

Phosphorylation of CLK2 at serine 34 and threonine 127 by AKT controls cell survival after ionizing radiation.

AKT phosphorylates components of the intrinsic cell survival machinery and promotes survival to various stimuli. In the present study, we identified CDC-like kinase 2 (CLK2) as a new substrate of AKT activation and elucidated its role in cell survival to ionizing radiation. AKT directly binds to and phosphorylates CLK2 on serine 34 and threonine 127, in vitro and in vivo. CLK2 phosphorylation was detected in HeLa cells overexpressing active AKT. In addition, we demonstrated that ionizing radiation induces CLK2 phosphorylation via AKT activation. In contrast, the suppression of endogenous AKT expression by siRNA inhibited CLK2 phosphorylation in response to 2 gray of γ-ray or insulin. Furthermore, we examined the effect of CLK2 on the survival of irradiated CCD-18Lu cells overexpressing Myc-CLK2. CLK2 overexpression significantly increased cell growth and inhibited cell death induced by 2 gray. The role of CLK2 in cell survival to ionizing radiation was dependent on the phosphorylation of serine 34 and threonine 127. Our results suggest that AKT activation controls cell survival to ionizing radiation by phosphorylating CLK2, revealing an important regulatory mechanism required for promoting cell survival.

Alteration of cytokine profiles in mice exposed to chronic low-dose ionizing radiation.

While a high-dose of ionizing radiation is generally harmful and causes damage to living organisms, a low-dose of radiation has been shown to be beneficial in a variety of animal models. To understand the basis for the effect of low-dose radiation in vivo, we examined the cellular and immunological changes evoked in mice exposed to low-dose radiation at very low (0.7mGy/h) and low (3.95mGy/h) dose rate for the total dose of 0.2 and 2Gy, respectively. Mice exposed to low-dose radiation, either at very low- or low-dose rate, demonstrated normal range of body weight and complete blood counts. Likewise, the number and percentage of peripheral lymphocyte populations, CD4(+) T, CD8(+) T, B, or NK cells, stayed unchanged following irradiation. Nonetheless, the sera from these mice exhibited elevated levels of IL-3, IL-4, leptin, MCP-1, MCP-5, MIP-1alpha, thrombopoietin, and VEGF along with slight reduction of IL-12p70, IL-13, IL-17, and IFN-gamma. This pattern of cytokine release suggests the stimulation of innate immunity facilitating myeloid differentiation and activation while suppressing pro-inflammatory responses and promoting differentiation of naïve T cells into T-helper 2, not T-helper 1, types. Collectively, our data highlight the subtle changes of cytokine milieu by chronic low-dose gamma-radiation, which may be associated with the functional benefits observed in various experimental models.