Radioprotective effects of Dragon's blood and its extract against gamma irradiation in mouse bone marrow cells

PurposeThe radioprotective effects of Dragon's blood (DB) and its extracts (DBE) were investigated using the chromosomal aberrant test, micronucleus and oxidative stress assay for anti-clastogenic and anti-oxidative activity.Materials and methodsAdult BALB/C mice were exposed to the whole body irradiation with 4 Gy ⁶⁰Co γ-rays. DB and DBE were administered orally once a day from 5 days prior to irradiation treatment to 1 day after irradiation. The mice were sacrificed on 24 h after irradiation. The cells of bone marrow were measured by counting different types of chromosomal aberrations and the frequency of micronuclei. Oxidative stress response was carried out by analysis of serum from blood.ResultsDB and DBE significantly decreased the number of bone marrow cells with chromosome aberrations after irradiation with respect to irradiated alone group. The administration of DB and DBE also significantly reduced the frequencies of micronucleated polychromatic erythrocytes (MPCE) and micronucleated normochromatic erythrocytes (MNCE). In addition, DB and DBE markedly increased the activity of antioxidant enzymes and the level of antioxidant molecular. Malondialdehyde (MDA) and nitric oxide (NO) levels in serum were significantly reduced by DB and DBE treatment.ConclusionsOur data suggested that DB and DBE have potential radioprotective properties in mouse bone marrow after ⁶⁰Co γ-ray exposure, which support their candidature as a potential radioprotective agent.     

Radioprotective efficacy of tocopherol succinate is mediated through granulocyte-colony stimulating factor

The purpose of this study was to elucidate the role of granulocyte colony-stimulating factor (G-CSF) induced by α-tocopherol succinate (TS) in protecting mice from total-body irradiation. CD2F1 mice were injected with a radioprotective dose of TS and the levels of cytokine in serum induced by TS were determined by multiplex Luminex. Neutralization of G-CSF was accomplished by administration of a G-CSF antibody and confirmed by cytokine analysis. The role of G-CSF on gastrointestinal tissue protection afforded by TS after irradiation (11 Gy, 0.6 Gy/min of ⁶⁰Co γ-radiation) was determined by analysis of jejunum histopathology for crypt, villi, mitotic figures, apoptosis, and cell proliferation. Our results demonstrate that TS protected mice against high doses of radiation-induced gastrointestinal damage and TS also induced very high levels of G-CSF and keratinocyte-derived chemokine (KC) production in peripheral blood 24 h after subcutaneous administration. When TS-injected mice were administered a neutralizing antibody to G-CSF, there was complete neutralization of G-CSF in circulating blood, and the protective effect of TS was significantly abrogated by G-CSF antibody. Histopathology of jejunum from TS-injected and irradiated mice demonstrated protection of gastrointestinal tissue, yet the protection was abrogated by administration of a G-CSF antibody. In conclusion, our current study suggests that induction of G-CSF resulting from TS administration is responsible for protection from ⁶⁰Co γ-radiation injury.     

γ-射线对大鼠小肠粘膜上皮细胞RNA合成的影响及其机理的研究

本文观察了15戈瑞γ-射线全身照射后,大鼠小肠粘膜上皮细胞核体外转录活性,从染色质结合的RNA聚合酶和可溶性RNA聚合酶活性变化探讨辐射对核转录活性的抑制机理。实验结果表明:(1)照后2小时、8小时和24小时,核转录活性分别下降22.7％、20.8％和28.2％;(2)染色质结合的RNA聚合酶活性变化与细胞核转录活性变化基本平行,提示核转录活性降低与核内染色质损伤有关;(3)照后24小时,核分离的可溶性RNA聚合酶抑制58％,提示辐射至少部分是通过抑制RNA聚合酶而影响细胞核转录活性;(4)在细胞核和分离的RNA聚合酶都观察到RNA聚合酶Ⅱ抑制程度大于RNA聚合酶Ⅰ和酶Ⅲ,酶活性下降主要表现在RNA聚合酶Ⅱ提示不同类RNA聚合酶对辐射的敏感性不同,酶Ⅱ对辐射更敏感。     

In vivo radioprotection studies of 3,3′-diselenodipropionic acid,a selenocystine derivative

3,3′-Diselenodipropionic acid (DSePA), a diselenide and a derivative of selenocystine, was evaluated for in vivo radioprotective effects in Swiss albino mice, at an intraperitoneal dose of 2 mg/kg body wt, for 5 days before whole-body exposure to γ-radiation. The radioprotective efficacy was evaluated by assessing protection of the hepatic tissue, the spleen, and the gastrointestinal (GI) tract and survival against sub- and supralethal doses of γ-radiation. DSePA inhibited radiation-induced hepatic lipid peroxidation, protein carbonylation, loss of hepatic function, and damage to the hepatic architecture. DSePA also attenuated the depletion of endogenous antioxidants such as glutathione, glutathione peroxidase, superoxide dismutase, and catalase in the livers of irradiated mice. DSePA also restored the radiation-induced reduction in villus height, crypt cell numbers, and spleen cellularity, indicating protective effects on the GI tract and the hematopoietic system. The results from single-cell gel electrophoresis of the peripheral blood leukocytes showed that DSePA can attenuate radiation-induced DNA damage. The mRNA expression analysis of genes revealed that DSePA augmented GADD45α and inhibited p21 in both spleen and liver tissues. DSePA also inhibited radiation-induced apoptosis in the spleen and reversed radiation-induced alterations in the expression of the proapoptotic BAX and the antiapoptotic Bcl-2 genes. In line with these observations, DSePA improved the 30-day survival of irradiated mice by 35.3%. In conclusion, these findings clearly confirm that DSePA exhibits protective effects against whole-body γ-radiation and the probable mechanisms of action involve the maintenance of antioxidant enzymes, prophylactic action through the attenuation of the DNA damage, and inhibition of apoptosis.     

Phloroglucinol (1,3,5-trihydroxybenzene) protects against ionizing radiation-induced cell damage through inhibition of oxidative stress in vitro and in vivo

Exposure of cells to γ-rays induces the production of reactive oxygen species (ROS) that play a main role in ionizing radiation damage. We have investigated the radioprotective effect of phloroglucinol (1,3,5-trihydroxybenzene), phlorotannin compound isolated from Ecklonia cava, against γ-ray radiation-induced oxidative damage in vitro and in vivo. Phloroglucinol significantly decreased the level of radiation-induced intracellular ROS and damage to cellular components such as the lipid, DNA and protein. Phloroglucinol enhanced cell viability that decreased after exposure to γ-rays and reduced radiation-induced apoptosis via inhibition of mitochondria mediated caspases pathway. Phloroglucinol reduced radiation-induced loss of the mitochondrial membrane action potential, reduced the levels of the active forms of caspase 9 and 3 and elevated the expression of bcl-2. Furthermore, the anti-apoptotic effect of phloroglucinol was exerted via inhibition of mitogen-activated protein kinase kinase-4 (MKK4/SEK1), c-Jun NH₂-terminal kinase (JNK) and activator protein-1 (AP-1) cascades induced by radiation exposure. Phloroglucinol restored the level of reduced glutathione (GSH) and protein expression of a catalytically active subunit of glutamate-cysteine ligase (GCL), which is a rate-limiting enzyme in GSH biosynthesis. In in vivo study, phloroglucinol administration in mice provided substantial protection against death and oxidative damage following whole-body irradiation. We examined survival with exposure to various radiation doses using the intestinal crypt assay and determined a dose reduction factor (DRF) of 1.24. Based on our findings, phloroglucinol may be possibly useful as a radioprotective compound.     

Activation of interferon-stimulated genes by gamma-ray irradiation independently of the ataxia telangiectasia mutated-p53 pathway

The ataxia telangiectasia mutated (ATM)-p53 pathway is a well-known main signal transduction pathway for cellular responses, which is activated by γ-ray irradiation. Microarray analysis showed changes in the expressions of IFN-stimulated genes (ISG) in γ-ray-irradiated Balb/cA/Atm-deficient mouse embryonic fibroblasts (MEF) (ATM-KO), indicating that another pathway for cellular responses besides the ATM-p53 pathway was activated by γ-ray irradiation. The basal expression levels of Irf7 and Stat1 in ATM-KO and p53-deficient MEFs (p53-KO) were higher than those in Atm-wild-type MEFs (ATM-WT) and p53-wild-type MEFs (p53-WT), respectively. Irradiation stimulated the expressions of Irf7 and Stat1 in ATM-KO, p53-KO, ATM-WT, and p53-WT, indicating that upregulation of Irf7 and Stat1 expressions by irradiation did not depend on the ATM-p53 pathway. When conditioned medium (CM) obtained from irradiated ATM-WT or ATM-KO was added to nonirradiated MEFs, the expressions of Irf7 and Stat1 increased. We predicted that gene activation in nonirradiated MEFs was caused by IFN-α/β. Unexpectedly, significant amount of IFN-α/β could not be detected in the CM from irradiated ATM-WT or ATM-KO. Meanwhile, increased expression of Ccl5 (RANTES) protein was detected in the CM from irradiated MEFs. These results indicate that ISGs were activated by γ-ray irradiation independently of the ATM-p53 pathway and gene activation was caused by radiation-induced soluble factors.     

软枣猕猴桃总黄酮对V79细胞的辐射防护作用

目的:研究软枣猕猴桃总黄酮的辐射防护活性。方法:以V79细胞辐射损伤模型为体外验证模型,利用回流醇提法提取的软枣猕猴桃总黄酮于辐射前处理细胞,细胞经8 Gy60Coγ射线辐射后,用多功能酶标仪检测细胞的存活率,用流式细胞仪检测细胞内活性氧及细胞凋亡率的变化。结果:用50～200μg/mL的软枣猕猴桃总黄酮于辐射前给药细胞,进行24 h培育,能抑制细胞内因辐射引起的活性氧上升,从而提高细胞存活率。结论:软枣猕猴桃总黄酮能清除细胞内由辐射产生的活性氧,降低细胞凋亡率,达到保护V79细胞的效果。     

Radioprotection of lungs by amifostine is associated with reduction in profibrogenic cytokine activity

Radiation-induced pulmonary toxicity causes significant morbidity and mortality in patients irradiated for lung cancer, breast cancer, lymphoma or thymoma. Amifostine is an important drug in the emerging field of cytoprotection. Recent advances in our understanding of the mechanism of radiation-induced injury at the molecular and cellular levels have stimulated interest in the development of effective radioprotective strategies. Accumulation of macrophages with associated production of reactive oxygen species (ROS) and production and activation of cytokines is a key process involved in the pathophysiology of radiation injury in the lung. The purpose of this study was to determine whether the mechanism of radioprotection by amifostine includes reduction in both macrophage activity and the expression and activation of profibrogenic cytokines. Our results demonstrated a reduction in both functional and histological radiation-induced lung injury by amifostine. In addition, this study is the first to demonstrate that amifostine given prior to irradiation reduced both the accumulation of macrophages and the expression/activation of lung tissue Tgfb1 which was followed by the reduction of plasma Tgfb1 levels during the development of radiation-induced lung injury. Future studies are needed to determine whether administration of amifostine both during and after radiotherapy may further increase its radioprotective effect.     

Flavonoids of <Emphasis Type="Italic">Rosa roxburghii</Emphasis> Tratt exhibit radioprotection and anti-apoptosis properties via the Bcl-2(Ca<Superscript>2+</Superscript>)/Caspase-3/PARP-1 pathway

The objective of our study was to assess the radioprotective effect of flavonoids extracted from Rosa roxburghii Tratt (FRT) and investigate the role of Bcl-2(Ca²⁺)/Caspase-3/PARP-1 pathway in radiation-induced apoptosis. Cells and mice were exposed to ⁶⁰Co γ-rays at a dose of 6 Gy. The radiation treatment induced significant effects on tissue pathological changes, apoptosis, Ca²⁺, ROS, DNA damage, and expression levels of Bcl-2, Caspase-3 (C-Caspase-3), and PARP-1. The results showed that FRT acted as an antioxidant, reduced DNA damage, corrected the pathological changes of the tissue induced by radiation, promoted the formation of spleen nodules, resisted sperm aberration, and protected the thymus. FRT significantly reduced cell apoptosis compared with the irradiation group. The expression of Ca²⁺ and C-Caspase-3 was decreased after FRT treatment compared with the radiation-treated group. At the same time, expression of prototype PARP-1 and Bcl-2 increased, leading to a decrease in the percentage of apoptosis cells in FRT treatment groups. We conclude that FRT acts as a radioprotector. Apoptosis signals were activated via the Bcl-2(Ca²⁺)/Caspase-3/PARP-1 pathway in irradiated cells and FRT inhibited this pathway of apoptosis by down-regulation of C-Caspase-3 and Ca²⁺ and up-regulation of prototype PARP-1 and Bcl-2.     

Radiation attenuates physiological angiogenesis by differential expression of VEGF, Ang-1, tie-2 and Ang-2 in rat brain

The etiology of radiation-induced cerebrovascular rarefaction remains unknown. In the present study, we examined the effect of whole-brain irradiation on endothelial cell (EC) proliferation/apoptosis and expression of various angiogenic factors in rat brain. F344 × BN rats received either whole-brain irradiation (a single dose of 10 Gy γ rays) or sham irradiation and were maintained for 4, 8 and 24 h after irradiation. Double immunofluorescence staining was employed to visualize EC proliferation/apoptosis in brain. The mRNA and protein expression levels of vascular endothelial growth factor (VEGF), angiopoietin-1 (Ang-1), endothelial-specific receptor tyrosine kinase (Tie-2), and Ang-2 in brain were determined by real-time RT-PCR and immunofluorescence staining. A significant reduction in CD31-immunoreactive cells was detected in irradiated rat brains compared with sham-irradiated controls. Whole-brain irradiation significantly suppressed EC proliferation and increased EC apoptosis. In addition, a significant decrease in mRNA and protein expression of VEGF, Ang-1 and Tie-2 was observed in irradiated rat brains. In contrast, whole-brain irradiation significantly upregulated Ang-2 expression in rat brains. The present study provides novel evidence that whole-brain irradiation differentially affects mRNA and protein expression of VEGF, Ang-1, Tie-2 and Ang-2. These changes are closely associated with decreased EC proliferation and increased EC apoptosis in brain.     

唐古特大黄多糖组分1对急性电离辐射损伤小鼠的保护作用

目的：探讨唐古特大黄多糖组分1（RTP1）对急性电离辐射损伤小鼠的保护作用。方法：采用昆明种小鼠,随机分为5组：正常对照组（Normal Control,NC）、辐射对照组（Irradiation Control,IC）以及RTP1低剂量组（200 mg/kg）、中（400 mg/kg）和高剂量组（800 mg/kg）,采用灌胃给药方式,连续14 d,NC组和IC组则给予等量的生理盐水,第14 d除NC组外,各组小鼠均接受2.0 Gy/只60Coγ射线照射1次,照射后24 h,检测小鼠胸腺和脾脏指数,测定肝脏超氧化物歧化酶（SOD）和谷胱甘肽过氧化物酶（GSH-Px）活性及丙二酰二醛（MDA）水平以及小鼠外周血象和骨髓嗜多染红细胞（PCE）微核数。结果：RTP1能够升高小鼠的胸腺、脾脏指数,增加肝脏SOD和GSH-Px活性,降低MDA水平,升高外周血中白细胞数并降低骨髓PCE微核数,与IC组比较有统计学意义（P〈0.05或P〈0.01）。结论：RTP1对辐射所致的小鼠损伤具有一定的保护作用。     

Radioprotective effects of ATP in human blood ex vivo

Damage to healthy tissue is a major limitation of radiotherapy treatment of cancer patients, leading to several side effects and complications. Radiation-induced release of pro-inflammatory cytokines is thought to be partially responsible for the radiation-associated complications. The aim of the present study was to investigate the protective effects of extracellular ATP on markers of oxidative stress, radiation-induced inflammation and DNA damage in irradiated blood ex vivo. ATP inhibited radiation-induced TNF-α release and increased IL-10 release. The inhibitory effect of ATP on TNF- α release was completely reversed by adenosine 5′-O-thiomonophosphate, indicating a P2Y₁₁ mediated effect. Furthermore, ATP attenuated radiation-induced DNA damage immediate, 3 and 6 h after irradiation. Our study indicates that ATP administration alleviates radiation-toxicity to blood cells, mainly by inhibiting radiation-induced inflammation and DNA damage.     

Radioprotective potential of histamine on rat small intestine and uterus

The aim of this study was to improve knowledge about histamine radioprotective potential investigating its effect on reducing ionising radiation-induced injury and genotoxic damage on the rat small intestine and uterus. Forty 10-week-old male and 40 female Sprague-Dawley rats were divided into 4 groups. Histamine and histamine-5Gy groups received a daily subcutaneous histamine injection (0.1 mg/kg) starting 24 h before irradiation. Histamine-5Gy and untreated-5Gy groups were irradiated with a dose of whole-body Cesium-137 irradiation. Three days after irradiation animals were sacrificed and tissues were removed, fixed, and stained with haematoxylin and eosin, and histological characteristics were evaluated. Proliferation, apoptosis and oxidative DNA markers were studied by immunohistochemistry, while micronucleus assay was performed to evaluate chromosomal damage. Histamine treatment reduced radiation-induced mucosal atrophy, oedema and vascular damage produced by ionising radiation, increasing the number of crypts per circumference (239±12 vs 160±10; P<0.01). This effect was associated with a reduction of radiation-induced intestinal crypts apoptosis. Additionally, histamine decreased the frequency of micronuclei formation and also significantly attenuated 8-OHdG immunoreactivity, a marker of DNA oxidative damage. Furthermore, radiation induced flattening of the endometrial surface, depletion of deep glands and reduced mitosis, effects that were completely blocked by histamine treatment. The expression of a proliferation marker in uterine luminal and glandular cells was markedly stimulated in histamine treated and irradiated rats.The obtained evidences indicate that histamine is a potential candidate as a safe radio-protective agent that might increase the therapeutic index of radiotherapy for intra-abdominal and pelvic cancers. However, its efficacy needs to be carefully investigated in prospective clinical trials.Key words: histamine, ionising radiation, radio-protectors, small intestine, uterus.     

Modification of radiation myelopathy by the transplantation of neural stem cells in the rat

In a novel approach, neural stem cells were transplanted to ameliorate radiation-induced myelopathy in the spinal cords of rats. A 12-mm section of the cervical spinal cord (T2-C2) of 5-week-old female Sprague-Dawley rats was locally irradiated with a single dose of 22 Gy of (60)Co gamma rays. This dose is known to produce myelopathy in all animals within 6 months of irradiation. After irradiation, the animals were subdivided into three groups, and at 90 days after irradiation, neural stem cells or saline (for controls) were injected into the spinal cord, intramedullary, at two sites positioned 6 mm apart on either side of the center of the irradiated length of spinal cord. The injection volume was 2 microl. Group I received a suspension of MHP36 cells, Group II MHP15 cells, and Group III (controls) two injections of 2 microl saline. All rats received 10 mg/kg cyclosporin (10 mg/ml) daily i.p. to produce immunosuppression. All animals that received saline (Group III) developed paralysis within 167 days of irradiation. The paralysis-free survival rates of rats that received transplanted MHP36 and MHP15 cells (Groups I and II) were 36.4% and 32% at 183 days, respectively. It was concluded that transplantation of neural stem cells 90 days after irradiation significantly (P = 0.03) ameliorated the expression of radiation-induced myelopathy in the spinal cords of rats.     

Sodium Selenite Improves Folliculogenesis in Radiation-Induced Ovarian Failure: A Mechanistic Approach

Radiotherapy is a major factor contributing to female infertility by inducing premature ovarian failure (POF). Therefore, the need for an effective radioprotective agent is evident. The present study investigated the mechanism of potential radioprotective effect of sodium selenite on radiation-induced ovarian failure and whether sodium selenite can stimulate in-vivo follicular development in experimental rats. Immature female Sprague-Dawely rats were either exposed to gamma-radiation (3.2 Gy, LD₂₀), once and/or treated with sodium selenite (0.5 mg/kg), once daily for one week before irradiation. Follicular and oocyte development, apoptotic markers, proliferation marker as well as oxidative stress markers were assessed 24-h after irradiation. In addition, fertility assessment was performed after female rats became completely mature at two months of age. Sodium selenite significantly enhanced follicular development as compared to the irradiated group. Sodium selenite significantly reversed the oxidative stress effects of radiation that was evidenced by increasing in lipid peroxide level and decreasing in glutathione level, and glutathione peroxidase (GPx) activity. Assessment of apoptosis and cell proliferation markers revealed that caspase 3 and cytochrome c expressions markedly-increased, whereas, PCNA expression markedly-decreased in the irradiated group; in contrast, sodium selenite treatment prevented these alterations. Histopathological examination further confirmed the radioprotective efficacy of sodium selenite and its in-vivo effect on ovarian follicles’ maturation. In conclusion, sodium selenite showed a radioprotective effect and improved folliculogenesis through increasing ovarian granulosa cells proliferation, estradiol and FSH secretion, and GPx activity, whilst decreasing lipid peroxidation and oxidative stress, leading to inhibition of the apoptosis pathway through decreasing the expressions of caspase 3 and cytochrome c.     

The cAMP signaling system inhibits the repair of γ-ray-induced DNA damage by promoting Epac1-mediated proteasomal degradation of XRCC1 protein in human lung cancer cells

Cyclic AMP is involved in the regulation of metabolism, gene expression, cellular growth and proliferation. Recently, the cAMP signaling system was found to modulate DNA-damaging agent-induced apoptosis by regulating the expression of Bcl-2 family proteins and inhibitors of apoptosis. Thus, we hypothesized that the cAMP signaling may modulate DNA repair activity, and we investigated the effects of the cAMP signaling system on γ-ray-induced DNA damage repair in lung cancer cells. Transient expression of a constitutively active mutant of stimulatory G protein (GαsQL) or treatment with forskolin, an adenylyl cyclase activator, augmented radiation-induced DNA damage and inhibited repair of the damage in H1299 lung cancer cells. Expression of GαsQL or treatment with forskolin or isoproterenol inhibited the radiation-induced expression of the XRCC1 protein, and exogenous expression of XRCC1 abolished the DNA repair-inhibiting effect of forskolin. Forskolin treatment promoted the ubiquitin and proteasome-dependent degradation of the XRCC1 protein, resulting in a significant decrease in the half-life of the protein after γ-ray irradiation. The effect of forskolin on XRCC1 expression was not inhibited by PKA inhibitor, but 8-pCPT-2'-O-Me-cAMP, an Epac-selective cAMP analog, increased ubiquitination of XRCC1 protein and decreased XRCC1 expression. Knockdown of Epac1 abolished the effect of 8-pCPT-2'-O-Me-cAMP and restored XRCC1 protein level following γ-ray irradiation. From these results, we conclude that the cAMP signaling system inhibits the repair of γ-ray-induced DNA damage by promoting the ubiquitin-proteasome dependent degradation of XRCC1 in an Epac-dependent pathway in lung cancer cells.     

Alterations in histone acetylation following exposure to <Superscript>60</Superscript>Co γ-rays and their relationship with chromosome damage in human lymphoblastoid cells

Chromosome damage is related to DNA damage and erroneous repair. It can cause cell dysfunction and ultimately induce carcinogenesis. Histone acetylation is crucial for regulating chromatin structure and DNA damage repair. Ionizing radiation (IR) can alter histone acetylation. However, variations in histone acetylation in response to IR exposure and the relationship between histone acetylation and IR-induced chromosome damage remains unclear. Hence, this study investigated the variation in the total acetylation levels of H3 and H4 in human lymphocytes exposed to 0–2 Gy ⁶⁰Co γ-rays. Suberoylanilide hydroxamic acid (SAHA), a histone deacetylase (HDAC) inhibitor, was added to modify the histone acetylation state of irradiated cells. Then, the total acetylation level, enzyme activity, dicentric plus centric rings (dic?+?r) frequencies, and micronucleus (MN) frequencies of the treated cells were analyzed. Results indicated that the acetylation levels of H3 and H4 significantly decreased at 1 and 24 h, respectively, after radiation exposure. The acetylation levels of H3 and H4 in irradiated groups treated with SAHA were significantly higher than those in irradiated groups that were not treated with SAHA. SAHA treatment inhibited HDAC activity in cells exposed to 0–1 Gy ⁶⁰Co γ-rays. SAHA treatment significantly decreased dic?+?r/cell and MN/cell in cells exposed to 0.5 or 1.0 Gy ⁶⁰Co γ-rays relative to that in cells that did not receive SAHA treatment. In conclusion, histone acetylation is significantly affected by IR and is involved in chromosome damage induced by ⁶⁰Co γ-radiation.     

大鼠放射性肺损伤模型的建立与动态观察

目的：建立并鉴定大鼠放射性肺损伤模型,摸索大鼠放射性肺损伤的病理变化规律,阐明氧化应激在其发生发展过程中的作用。方法：采用60Co源22Gy单次照射SD大鼠全肺。分别于照射前、照后1天,7天,15天,21天,30天,60天,120天活杀大鼠,计算肺系数,右肺行HE染色、Masson染色及天狼猩红染色,观察肺组织病理变化并对大鼠肺泡炎及纤维化程度进行评分,免疫组化法检测肺组织廿SMA表达情况;左肺进行羟脯氨酸含量测定;血清测定MDA含量、总SOD活力和TGF-β1含量。结果：（1）大鼠肺脏于照后15天开始出现明显大体改变,病理学表现为间质性渗出性炎症并随时间延长逐渐加重,照后60天至120天肺脏塌陷,表面可见纤维化病灶,病理改变以肺间隔内细胞增生和胶原纤维沉积为主;（2）血清T-SOD活力照后1天至7天短暂增加后其活力持续降低;血清MDA含量和TGF-β1含量随时间时间延长逐渐增高;（3）照后60天肺组织a-SMA表达明显增加,至照后120天最为显著。结论：成功建立了大鼠放射性肺损伤模型并阐述了其病理变化规律;氧化应激参与了放射性肺损伤的病理过程。为其防治提供了实验基础和理论依据。     

Role of CD13/aminopeptidase N in rat lymphocytic alveolitis caused by thoracic irradiation

CD13/aminopeptidase N is a cell surface glycoprotein that is widely distributed in a variety of mammalian cells. It was recently shown to have chemotactic activity for T lymphocytes. This study examined the role of CD13/aminopeptidase N in lymphocytic alveolitis in radiation-induced lung injury caused by a single-dose thoracic irradiation (15 Gy) in rats. Significantly increased aminopeptidase activity was detected in bronchoalveolar lavage fluid obtained from irradiated rats at 4 weeks after irradiation compared to the activity in unirradiated rats. Significantly higher aminopeptidase activity was detected on alveolar macrophages from irradiated rats at 2 and 4 weeks than on those from unirradiated rats. Western blot analysis showed an increased expression of CD13/aminopeptidase N protein in alveolar macrophages from irradiated rats at 4 weeks. Chemotactic activity for normal rat lymphocytes was detected in bronchoalveolar lavage fluid from irradiated rats at 4 weeks, and approximately 60% of the activity was inhibited by pretreatment of bronchoalveolar lavage fluid with bestatin, a specific aminopeptidase inhibitor. This study suggests that CD13/aminopeptidase N may play an important role as a lymphocyte chemoattractant in lymphocyte-mediated alveolitis in experimental radiation-induced lung injury.     

Bone marrow stromal cell transplantation mitigates radiation-induced gastrointestinal syndrome in mice

Background

Nuclear accidents and terrorism presents a serious threat for mass casualty. While bone-marrow transplantation might mitigate hematopoietic syndrome, currently there are no approved medical countermeasures to alleviate radiation-induced gastrointestinal syndrome (RIGS), resulting from direct cytocidal effects on intestinal stem cells (ISC) and crypt stromal cells. We examined whether bone marrow-derived adherent stromal cell transplantation (BMSCT) could restitute irradiated intestinal stem cells niche and mitigate radiation-induced gastrointestinal syndrome.

Methodology/Principal Findings

Autologous bone marrow was cultured in mesenchymal basal medium and adherent cells were harvested for transplantation to C57Bl6 mice, 24 and 72 hours after lethal whole body irradiation (10.4 Gy) or abdominal irradiation (16–20 Gy) in a single fraction. Mesenchymal, endothelial and myeloid population were characterized by flow cytometry. Intestinal crypt regeneration and absorptive function was assessed by histopathology and xylose absorption assay, respectively. In contrast to 100% mortality in irradiated controls, BMSCT mitigated RIGS and rescued mice from radiation lethality after 18 Gy of abdominal irradiation or 10.4 Gy whole body irradiation with 100% survival (p<0.0007 and p<0.0009 respectively) beyond 25 days. Transplantation of enriched myeloid and non-myeloid fractions failed to improve survival. BMASCT induced ISC regeneration, restitution of the ISC niche and xylose absorption. Serum levels of intestinal radioprotective factors, such as, R-Spondin1, KGF, PDGF and FGF2, and anti-inflammatory cytokines were elevated, while inflammatory cytokines were down regulated.

Conclusion/Significance

Mitigation of lethal intestinal injury, following high doses of irradiation, can be achieved by intravenous transplantation of marrow-derived stromal cells, including mesenchymal, endothelial and macrophage cell population. BMASCT increases blood levels of intestinal growth factors and induces regeneration of the irradiated host ISC niche, thus providing a platform to discover potential radiation mitigators and protectors for acute radiation syndromes and chemo-radiation therapy of abdominal malignancies.