Relative roles of ICAM-1 and VCAM-1 in the pathogenesis of experimental radiation-induced intestinal inflammation

BAP31 regulates the expression of ICAM-1/VCAM-1 via MyD88/NF-κB pathway in acute lung injury mice model

AIMS

The cell adhesion molecules (CAMs) that mediate neutrophil-endothelium cell adhesion are deeply involved in the pathogenesis of acute lung injury (ALI). B-cell receptor associated protein 31 (BAP31) has been reported to engage in the expression of some CAMs. This study was undertaken to explore whether BAP31 in endotheliocyte affects the pathological process of ALI by regulating CAMs, and its possible mechanism.

MAIN METHODS

Our study used the shBAP31 endothelium cell lines and endothelial-specific BAP31 conditional knockdown mice constructed via Cre/loxP system. Hematoxylin and eosin staining was used to observe the histopathological manifestations. The adhesion of neutrophils to vascular wall was examined by intravital microscopy. The nuclear translocation of NF-κB was observed by immunofluorescence staining assay. Flow cytometric, real-time polymerase chain reaction and Western blot assay were performed to determine the expression of CAMs and key proteins in MyD88/NF-κB-related signaling pathway. Luciferase reporter and chromatin immunoprecipitation assay were analyzed for transcriptional activity of ICAM-1 and VCAM-1.

KEY FINDINGS

Mechanistic investigations indicated that endothelium-specific BAP31 depletion dramatically reduced the capacity of neutrophils adherence to endothelial cells (ECs), which was mainly attributed to the significant downregulation of ICAM-1 (p < 0.05) and VCAM-1 (p < 0.05) expression. Interestingly, BAP31 knockdown apparently deactivated MyD88/TRAF6-mediated TAK1/NF-κB and PI3K/Akt signaling cascades, resulting in the inhibition of NF-κB activation and nuclear translocation.

SIGNIFICANCE

Our data furnished convincing evidence that BAP31 deficiency performs a mitigative effect on ALI by decreasing neutrophils-ECs adhesion. These findings identified BAP31 as a promising protein for regulating the pathogenesis process of ALI.

Effects of Microbeam Irradiation on Rodent Esophageal Smooth Muscle Contraction

BACKGROUND

High-dose-rate radiotherapy has shown promising results with respect to normal tissue preservation. We developed an ex vivo model to study the physiological effects of experimental radiotherapy in the rodent esophageal smooth muscle.

METHODS

We assessed the physiological parameters of the esophageal function in ex vivo preparations of the proximal, middle, and distal segments in the organ bath. High-dose-rate synchrotron irradiation was conducted using both the microbeam irradiation (MBI) technique with peak doses greater than 200 Gy and broadbeam irradiation (BBI) with doses ranging between 3.5-4 Gy.

RESULTS

Neither MBI nor BBI affected the function of the contractile apparatus. While peak latency and maximal force change were not affected in the BBI group, and no changes were seen in the proximal esophagus segments after MBI, a significant increase in peak latency and a decrease in maximal force change was observed in the middle and distal esophageal segments.

CONCLUSION

No severe changes in physiological parameters of esophageal contraction were determined after high-dose-rate radiotherapy in our model, but our results indicate a delayed esophageal function. From the clinical perspective, the observed increase in peak latency and decreased maximal force change may indicate delayed esophageal transit.

Radiotherapy induced immunogenic cell death by remodeling tumor immune microenvironment

Emerging evidence indicates that the induction of radiotherapy(RT) on the immunogenic cell death (ICD) is not only dependent on its direct cytotoxic effect, changes in the tumor immune microenvironment also play an important role in it. Tumor immune microenvironment (TIME) refers to the immune microenvironment that tumor cells exist, including tumor cells, inflammatory cells, immune cells, various signaling molecules and extracellular matrix. TIME has a barrier effect on the anti-tumor function of immune cells, which can inhibit all stages of anti-tumor immune response. The remodeling of TIME caused by RT may affect the degree of immunogenicity, and make it change from immunosuppressive phenotype to immunostimulatory phenotype. It is of great significance to reveal the causes of immune escape of tumor cells, especially for the treatment of drug-resistant tumor. In this review, we focus on the effect of RT on the TIME, the mechanism of RT in reversing the TIME to suppress intrinsic immunity, and the sensitization effect of the remodeling of TIME caused by RT on the effectiveness of immunotherapy.

Do urinary metals associate with the homeostasis of inflammatory mediators? Results from the perspective of inflammatory signaling in middle-aged and older adults

OBJECTIVE

We aimed to investigate whether urinary metal mixtures are associated with the homeostasis of inflammatory mediators in middle-aged and older adults.

METHODS

A four-visit repeated-measures study was conducted with 98 middle-aged and older adults from five communities in Beijing, China. Only one person was lost to follow-up at the third visit. Ultimately, 391 observations were included in the analysis. The urinary concentrations of 10 metals were measured at each visit using inductively coupled plasma mass spectrometry (ICP-MS) with a limit of detection (LOD) ranging from 0.002 to 0.173 µg/L, and the detection rates were all above 84%. Similarly, 14 serum inflammatory mediators were measured using a Beckman Coulter analyzer and the Bio-Plex MAGPIX system. A linear mixed model (LMM), LMM with least absolute shrinkage and selection operator regularization (LMMLASSO), and Bayesian kernel machine regression (BKMR) were adopted to explore the effects of urinary metal mixtures on inflammatory mediators.

RESULTS

In LMM, a two-fold increase in urinary cesium (Cs) and chromium (Cr) was statistically associated with -35.22% (95% confidence interval [CI]: -53.17, -10.40) changes in interleukin 6 (IL-6) and -11.13% (95 %CI: -20.67, -0.44) in IL-8. Urinary copper (Cu) and selenium (Se) was statistically associated with IL-6 (88.10%, 95%CI: 34.92, 162.24) and tumor necrosis factor-alpha (TNF-α) (22.32%, 95%CI: 3.28, 44.12), respectively. Similar results were observed for the LMMLASSO and BKMR. Furthermore, Cr, Cs, Cu, and Se were significantly associated with other inflammatory regulatory network mediators. For example, urinary Cs was statistically associated with endothelin-1, and Cr was statistically associated with endothelin-1 and intercellular adhesion molecule 1 (ICAM-1). Finally, the interaction effects of Cu with various metals on inflammatory mediators were observed.

CONCLUSION

Our findings suggest that Cr, Cs, Cu, and Se may disrupt the homeostasis of inflammatory mediators, providing insight into the potential pathophysiological mechanisms of metal mixtures and chronic diseases.

Umbelliferone ameliorates ulcerative colitis induced by acetic acid via modulation of TLR4/NF-κB-p65/iNOS and SIRT1/PPARγ signaling pathways in rats

Ulcerative colitis (UC) is a common chronic, idiopathic inflammatory bowel disease associated with inflammatory perturbation and oxidative stress. Umbelliferone (UMB) is a potent anti-inflammatory and antioxidant coumarin derivative. Depending on the possible mechanisms, we aimed to explore and elucidate the therapeutic potential of UMB on UC-inflammatory response and oxidative injury-induced via intrarectal administration of acetic acid (AA) in rats. Animals were assigned into four groups: control group, UMB (30 mg/kg, oral)-treated group, AA-induced colitis model group (2 ml of AA; 3% v/v), and colitis treated with UMB group. The results showed that UMB improved macroscopic and histological tissue injury caused by the AA. Mechanistically, UMB reduced the elevated colonic TNF-α, IL-6, MPO, and VCAM-1 and downregulated the gene and protein expression of TLR4, NF-κB, and iNOS signaling factors, exhibiting potent anti-inflammatory effects. Moreover, UMB upregulated the gene and protein expression of both SIRT1 and PPARγ signaling pathways, thereby inhibiting both oxidative injury and inflammatory response. Conclusively, UMB protected rats against AA-induced UC by suppressing the TLR4/NF-κB-p65/iNOS signaling pathway and promoting the SIRT1/PPARγ signaling. Our results showed the effectiveness of UMB in alleviating the pathogenesis of UC and introduced it as a possible therapeutic applicant for clinical application.

Immunomodulation by radiotherapy in tumour control and normal tissue toxicity

Radiotherapy (RT) is a highly effective anticancer treatment that is delivered to more than half of all patients with cancer. In addition to the well-documented direct cytotoxic effects, RT can have immunomodulatory effects on the tumour and surrounding tissues. These effects are thought to underlie the so-called abscopal responses, whereby RT generates systemic antitumour immunity outside the irradiated tumour. The full scope of these immune changes remains unclear but is likely to involve multiple components, such as immune cells, the extracellular matrix, endothelial and epithelial cells and a myriad of chemokines and cytokines, including transforming growth factor-β (TGFβ). In normal tissues exposed to RT during cancer therapy, acute immune changes may ultimately lead to chronic inflammation and RT-induced toxicity and organ dysfunction, which limits the quality of life of survivors of cancer. Here we discuss the emerging understanding of RT-induced immune effects with particular focus on the lungs and gut and the potential immune crosstalk that occurs between these tissues.

VCAM-1 Is Upregulated in Uranium Miners Compared to Other Miners

The United States has a rich history of mining including uranium (U)-mining, coal mining, and other metal mining. Cardiovascular diseases (CVD) are largely understudied in miners and recent literature suggests that when compared to non-U miners, U-miners are more likely to report CVD. However, the molecular basis for this phenomenon is currently unknown. In this pilot study, a New Mexico (NM)-based occupational cohort of current and former miners (n = 44) were recruited via a mobile screening clinic for miners. Serum- and endothelial-based endpoints were used to assess circulating inflammatory potential relevant to CVD. Non-U miners reported significantly fewer pack years of smoking than U-miners. Circulating biomarkers of interest revealed that U-miners had significantly greater serum amyloid A (SAA), soluble intercellular adhesion molecule 1 (ICAM-1, ng/mL), soluble vascular cell adhesion molecule 1 (VCAM-1, ng/mL), and VCAM-1 mRNA expression, as determined by the serum cumulative inflammatory potential (SCIP) assay, an endothelial-based assay. Even after adjusting for various covariates, including age, multivariable analysis determined that U-miners had significantly upregulated VCAM-1 mRNA. In conclusion, VCAM-1 may be an important biomarker and possible contributor of CVD in U-miners. Further research to explore this mechanism may be warranted.

Biomarkers of Atherosclerotic Vascular Disease in Workers Chronically Exposed to Ionizing Radiation

ABSTRACT

It is well established that cohorts of individuals exposed to ionizing radiation demonstrate increased risks of cardio- and cerebrovascular diseases. However, mechanisms of these radiation-induced diseases developing in individuals exposed to ionizing radiation remain unclear. To identify biomarkers of the atherosclerotic vessel damage in workers chronically exposed to ionizing radiation, this study considered 49 workers of the Russian nuclear production facility-the Mayak Production Association (mean age of 68.73 ± 6.92 years)-and 38 unexposed individuals (mean age of 68.84 ± 6.20 y) who had never been exposed to ionizing radiation (control). All workers were chronically exposed to combined radiation (external gamma rays and internal alpha particles). The mean cumulative liver absorbed dose from external gamma-ray exposure was 0.18 ± 0.12 Gy; the mean cumulative liver absorbed dose from internal alpha-particles was 0.14 ± 0.21 Gy. Levels of biomarkers in blood serum of the study participants were measured using the ELISA method. Elevated levels of apolipoprotein B, superoxide dismutase, monocyte chemoattractant protein 1, vascular cell adhesion protein 1, and a decreased level of endothelin-1 were observed in blood serum of Mayak PA workers chronically exposed to combined radiation compared to control individuals. A significant positive correlation was demonstrated between the vascular cell adhesion protein 1 level and cumulative liver absorbed doses from external gamma radiation and internal alpha radiation. Findings of the study suggest that molecular changes in blood of individuals occupationally exposed to ionizing radiation (combined internal exposure to alpha particles and external exposure to gamma rays) may indicate dyslipidemia, oxidative stress, inflammation, and endothelial dysfunction involved in atherosclerosis development.

Inhibitory Effects of Bilirubin on Colonization and Migration of A431 and SK-MEL-3 Skin Cancer Cells Compared with Human Dermal Fibroblasts (HDF)

This study evaluated the inhibitory effects of bilirubin on colony formation and cell migration of melanoma and non-melanoma skin cancer cell lines SK-MEL-3 and A431, compared with normal human dermal fibroblasts (HDF). The IC₅₀ obtained from the MTT assay was 125, 100, and 75 μM bilirubin for HDF, A431, and SK-MEL-3 cells, respectively. The colony formation and cell migration of cancer cells, treated with 100 μM bilirubin, were reduced significantly (p < 0.05). Bilirubin decreased cell adhesion and inhibited cell colonization via inducing apoptosis and cell death. Also by interaction with migration main factors, bilirubin caused inhibition the cell migration.

Wound Healing After Alkali Burn Injury of the Cornea Involves Nox4-Type NADPH Oxidase

Purpose

Corneal injury that occurs after burning with alkali initiates wound-healing processes, including inflammation, neovascularization, and fibrosis. Excessive reactions to injury can reduce corneal transparency and thereby compromise vision. The NADPH oxidase (Nox) enzyme complex is known to be involved in cell signaling for wound-healing angiogenesis, but its role in corneal neovascularization has been little studied.

Methods

The center corneas of wild-type and Nox4 knockout (KO) mice were injured with 3 µL 1 M NaOH, while the contralateral corneas remained untouched. On day 7, mRNA expression levels of NADPH oxidase isoforms, the proangiogenic factors VEGF-A and TGFβ1, and proinflammatory genes ICAM-1 and VCAM-1 were determined. Corneal neovascularization and fibrosis were visualized using PECAM-1 antibody and picrosirius red staining, respectively, on the same day.

Results

Expressions of both Nox2 and Nox4 gene isoforms as well as the above genes were markedly increased in the injured corneas at 7 days. Injured corneas showed neovascularization and fibrosis as well as an increase in clinical opacity score. All responses stimulated by alkali burn were abrogated in Nox4 KO mice.

Conclusions

Nox4 could be a new target to treat pathologic corneal wound-healing responses and such targeting might prevent blindness caused by burn injuries.

Protective Effects of Biscoclaurine Alkaloids on Leukopenia Induced by 60Co-γ Radiation

Objective

Leukopenia, a common complication of tumor chemoradiotherapy, contributes serious damage to the hematopoietic, gastrointestinal, and immune systems of the body and can cause delay, discontinuation, or even failure to tumor treatment, thereby greatly threatening human health. The present study aims to investigate the protective effects of biscoclaurine alkaloids (BA) on leukopenia.

Methods

This study was conducted on 60 Kunming mice, which were randomly divided into six groups containing 10 animals each. A hematology analyzer was used to count white blood cells (WBC) in the peripheral blood cell. Mice serum was collected, and the granulocyte-macrophage colony-stimulating factor, vascular cell adhesion molecule 1 (VCAM-1), and interferon-γ (IFN-γ) were detected by enzyme-linked immunosorbent assays. Pathological changes were detected through hematoxylin and eosin staining in the liver and spleen of mice. The spleen and liver ultrastructures were observed via electron microscopy.

Results

Results showed that BA ameliorated WBC, PLT reduction in the peripheral blood and significantly increased the levels of IFN-γ and VCAM-1 in mice serum. BA reduced ionizing radiation-induced injuries to spleen, mitigated the reduction of superoxide dismutase (SOD), and significantly decreased the malonaldehyde (MDA) and xanthine oxidase (XOD) levels in the liver.

Conclusion

BA enhanced the immune and hematopoietic functions and ameliorated the oxidative stress induced by ⁶⁰Co-γ radiation, revealing its therapeutic potential both as a radioprotector and as a radiation mitigator for leukopenia induced by ⁶⁰Co-γ radiation.

Food Supplements to Mitigate Detrimental Effects of Pelvic Radiotherapy

Pelvic radiotherapy has been frequently reported to cause acute and late onset gastrointestinal (GI) toxicities associated with significant morbidity and mortality. Although the underlying mechanisms of pelvic radiation-induced GI toxicity are poorly understood, they are known to involve a complex interplay between all cell types comprising the intestinal wall. Furthermore, increasing evidence states that the human gut microbiome plays a role in the development of radiation-induced health damaging effects. Gut microbial dysbiosis leads to diarrhea and fatigue in half of the patients. As a result, reinforcement of the microbiome has become a hot topic in various medical disciplines. To counteract GI radiotoxicities, apart from traditional pharmacological compounds, adjuvant therapies are being developed including food supplements like vitamins, prebiotics, and probiotics. Despite the easy, cheap, safe, and feasible approach to protect patients against acute radiation-induced toxicity, clinical trials have yielded contradictory results. In this review, a detailed overview is given of the various clinical, intestinal manifestations after pelvic irradiation as well as the role of the gut microbiome herein. Furthermore, whilst discussing possible strategies to prevent these symptoms, food supplements are presented as auspicious, prophylactic, and therapeutic options to mitigate acute pelvic radiation-induced GI injury by exploring their molecular mechanisms of action.

Mechanisms of vascular dysfunction evoked by ionizing radiation and possible targets for its pharmacological correction

Ionizing radiation (IR) leads to a variety of the cardiovascular diseases, including the arterial hypertension. A number of studies have demonstrated that blood vessels represent important target for IR, and the endothelium is one of the most vulnerable components of the vascular wall. IR causes an inhibition of nitric oxide (NO)-mediated endothelium-dependent vasodilatation and generation of reactive oxygen (ROS) and nitrogen (RNS) species trigger this process. Inhibition of NO-mediated vasodilatation could be due to endothelial NO synthase (eNOS) down-regulation, inactivation of endothelium-derived NO, and abnormalities in diffusion of NO from the endothelial cells (ECs) leading to a decrease in NO bioavailability. Beside this, IR suppresses endothelial large conductance Ca²⁺-activated K⁺ channels (BK_Ca) activity, which control NO synthesis. IR also leads to inhibition of the BK_Ca current in vascular smooth muscle cells (SMCs) which is mediated by protein kinase C (PKC). On the other hand, IR-evoked enhanced vascular contractility may result from PKC-mediated increase in SMCs myofilament Ca²⁺ sensitivity. Also, IR evokes vascular wall inflammation and atherosclerosis development. Vascular function damaged by IR can be effectively restored by quercetin-filled phosphatidylcholine liposomes and mesenchymal stem cells injection. Using RNA-interference technique targeted to different PKC isoforms can also be a perspective approach for pharmacological treatment of IR-induced vascular dysfunction.

The importance of the vascular endothelial barrier in the immune-inflammatory response induced by radiotherapy

Altered by ionising radiation, the vascular network is considered as a prime target to limit normal tissue damage and improve tumour control in radiotherapy (RT). Irradiation damages and/or activates endothelial cells, which then participate in the recruitment of circulating cells, especially by overexpressing cell adhesion molecules, but also by other as yet unknown mechanisms. Radiation-induced lesions are associated with infiltration of immune-inflammatory cells from the blood and/or the lymph circulation. Damaged cells from the tissues and immune-inflammatory resident cells release factors that attract cells from the circulation, leading to the restoration of tissue balance by fighting against infection, elimination of damaged cells and healing of the injured area. In normal tissues that surround the tumours, the development of an immune-inflammatory reaction in response to radiation-induced tissue injury can turn out to be chronic and deleterious for the organ concerned, potentially leading to fibrosis and/or necrosis of the irradiated area. Similarly, tumours can elicit an immune-inflammation reaction, which can be initialised and amplified by cancer therapy such as radiotherapy, although immune checkpoints often allow many cancers to be protected by inhibiting the T-cell signal. Herein, we have explored the involvement of vascular endothelium in the fate of healthy tissues and tumours undergoing radiotherapy. This review also covers current investigations that take advantage of the radiation-induced response of the vasculature to spare healthy tissue and/or target tumours better.

Bowel Radiation Injury: Complexity of the Pathophysiology and Promises of Cell and Tissue Engineering

Ionizing radiation is effective to treat malignant pelvic cancers, but the toxicity to surrounding healthy tissue remains a substantial limitation. Early and late side effects not only limit the escalation of the radiation dose to the tumor but may also be life-threatening in some patients. Numerous preclinical studies determined specific mechanisms induced after irradiation in different compartments of the intestine. This review outlines the complexity of the pathogenesis, highlighting the roles of the epithelial barrier in the vascular network, and the inflammatory microenvironment, which together lead to chronic fibrosis. Despite the large number of pharmacological molecules available, the studies presented in this review provide encouraging proof of concept regarding the use of mesenchymal stromal cell (MSC) therapy to treat radiation-induced intestinal damage. The therapeutic efficacy of MSCs has been demonstrated in animal models and in patients, but an enormous number of cells and multiple injections are needed due to their poor engraftment capacity. Moreover, it has been observed that although MSCs have pleiotropic effects, some intestinal compartments are less restored after a high dose of irradiation. Future research should seek to optimize the efficacy of the injected cells, particularly with regard to extending their life span in the irradiated tissue. Moreover, improving the host microenvironment, combining MSCs with other specific regenerative cells, or introducing new tissue engineering strategies could be tested as methods to treat the severe side effects of pelvic radiotherapy.

Coordination of early cellular reactions during activation of bone resorption in the rat mandible periosteum: An immunohistochemical study

The activation step of bone remodeling remains poorly characterized. Activation comprises determination of the site to be remodeled, osteoclast precursor recruitment, their migration to the site of remodeling, and differentiation. These actions involve different compartments and cell types. The aim of this study was to investigate events and cell types involved during activation. We used a bone remodeling model in rats where extractions of the upper jaw molars initiate remodeling of the antagonist lower jaw (mandible) cortex along the periosteum. In this model osteoclastic resorption peaks 4 days after extractions. We previously reported that mast cell activation in the periosteum fibrous compartment is an early event of activation, associated with recruitment of circulating monocyte osteoclast precursors. By using immunohistochemistry, we observed 9 hours after induction a spatially oriented expression of InterCellular Adhesion Molecule-1 in the vessels that was inhibited by antagonists of histamine receptors 1 and 2. It was followed at 12 hours by the recruitment of ED1+ monocytes. In parallel, at 9 hours, Vascular Cellular Adhesion Molecule-1+ fibroblast-like cells scattered in the fibrous compartment of the periosteum between the vessels and the osteogenic compartment increased; these cells may be implicated in osteoclast precursor migration. Receptor Activator of NF KappaB Ligand+ cells increased at 12 hours in the osteogenic compartment and reached a peak at 18 hours. At 24 hours the numbers of osteogenic cells and subjacent osteocytes expressing semaphorin 3a, a repulsive for osteoclast precursors, decreased before returning to baseline at 48 hours. These data show that during activation the two periosteum compartments and several cell types are coordinated to recruit and guide osteoclast precursors towards the bone surface.

In vivo imaging of endothelial cell adhesion molecule expression after radiosurgery in an animal model of arteriovenous malformation

Focussed radiosurgery may provide a means of inducing molecular changes on the luminal surface of diseased endothelium to allow targeted delivery of novel therapeutic compounds. We investigated the potential of ionizing radiation to induce surface expression of intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) on endothelial cells (EC) in vitro and in vivo, to assess their suitability as vascular targets in irradiated arteriovenous malformations (AVMs). Cultured brain microvascular EC were irradiated by linear accelerator at single doses of 0, 5, 15 or 25 Gy and expression of ICAM-1 and VCAM-1 measured by qRT-PCR, Western, ELISA and immunocytochemistry. In vivo, near-infrared (NIR) fluorescence optical imaging using Xenolight 750-conjugated ICAM-1 or VCAM-1 antibodies examined luminal biodistribution over 84 days in a rat AVM model after Gamma Knife surgery at a single 15 Gy dose. ICAM-1 and VCAM-1 were minimally expressed on untreated EC in vitro. Doses of 15 and 25 Gy stimulated expression equally; 5 Gy was not different from the unirradiated. In vivo, normal vessels did not bind or retain the fluorescent probes, however binding was significant in AVM vessels. No additive increases in probe binding were found in response to radiosurgery at a dose of 15 Gy. In summary, radiation induces adhesion molecule expression in vitro but elevated baseline levels in AVM vessels precludes further induction in vivo. These molecules may be suitable targets in irradiated vessels without hemodynamic derangement, but not AVMs. These findings demonstrate the importance of using flow-modulated, pre-clinical animal models for validating candidate proteins for vascular targeting in irradiated AVMs.

Bilirubin Prevents Atherosclerotic Lesion Formation in Low-Density Lipoprotein Receptor-Deficient Mice by Inhibiting Endothelial VCAM-1 and ICAM-1 Signaling

Background

Numerous epidemiological studies support an inverse association between serum bilirubin levels and the incidence of cardiovascular disease; however, the mechanism(s) by which bilirubin may protect against atherosclerosis is undefined. The goals of the present investigations were to assess the ability of bilirubin to prevent atherosclerotic plaque formation in low‐density lipoprotein receptor‐deficient (Ldlr^−/−) mice and elucidate the molecular processes underlying this effect.

Methods and Results

Bilirubin, at physiological concentrations (≤20 μmol/L), dose‐dependently inhibits THP‐1 monocyte migration across tumor necrosis factor α–activated human umbilical vein endothelial cell monolayers without altering leukocyte binding or cytokine production. A potent antioxidant, bilirubin effectively blocks the generation of cellular reactive oxygen species induced by the cross‐linking of endothelial vascular cell adhesion molecule 1 (VCAM‐1) or intercellular adhesion molecule 1 (ICAM‐1). These findings were validated by treating cells with blocking antibodies or with specific inhibitors of VCAM‐1 and ICAM‐1 signaling. When administered to Ldlr^−/− mice on a Western diet, bilirubin (30 mg/kg intraperitoneally) prevents atherosclerotic plaque formation, but does not alter circulating cholesterol or chemokine levels. Aortic roots from bilirubin‐treated animals exhibit reduced lipid and collagen deposition, decreased infiltration of monocytes and lymphocytes, fewer smooth muscle cells, and diminished levels of chlorotyrosine and nitrotyrosine, without changes in VCAM‐1 or ICAM‐1 expression.

Conclusions

Bilirubin suppresses atherosclerotic plaque formation in Ldlr^−/− mice by disrupting endothelial VCAM‐1‐ and ICAM‐1‐mediated leukocyte migration through the scavenging of reactive oxygen species signaling intermediaries. These findings suggest a potential mechanism for the apparent cardioprotective effects of bilirubin.

Translational Research to Improve the Efficacy of Carbon Ion Radiotherapy: Experience of Gunma University

Carbon ion radiotherapy holds great promise for cancer therapy. Clinical data show that carbon ion radiotherapy is an effective treatment for tumors that are resistant to X-ray radiotherapy. Since 1994 in Japan, the National Institute of Radiological Sciences has been heading the development of carbon ion radiotherapy using the Heavy Ion Medical Accelerator in Chiba. The Gunma University Heavy Ion Medical Center (GHMC) was established in the year 2006 as a proof-of-principle institute for carbon ion radiotherapy with a view to facilitating the worldwide spread of compact accelerator systems. Along with the management of more than 1900 cancer patients to date, GHMC engages in translational research to improve the treatment efficacy of carbon ion radiotherapy. Research aimed at guiding patient selection is of utmost importance for making the most of carbon ion radiotherapy, which is an extremely limited medical resource. Intratumoral oxygen levels, radiation-induced cellular apoptosis, the capacity to repair DNA double-strand breaks, and the mutational status of tumor protein p53 and epidermal growth factor receptor genes are all associated with X-ray sensitivity. Assays for these factors are useful in the identification of X-ray-resistant tumors for which carbon ion radiotherapy would be beneficial. Research aimed at optimizing treatments based on carbon ion radiotherapy is also important. This includes assessment of dose fractionation, normal tissue toxicity, tumor cell motility, and bystander effects. Furthermore, the efficacy of carbon ion radiotherapy will likely be enhanced by research into combined treatment with other modalities such as chemotherapy. Several clinically available chemotherapeutic drugs (carboplatin, paclitaxel, and etoposide) and drugs at the developmental stage (Wee-1 and heat shock protein 90 inhibitors) show a sensitizing effect on tumor cells treated with carbon ions. Additionally, the efficacy of carbon ion radiotherapy can be improved by combining it with cancer immunotherapy. Clinical validation of preclinical findings is necessary to further improve the treatment efficacy of carbon ion radiotherapy.

Bilirubin acts as an endogenous regulator of inflammation by disrupting adhesion molecule-mediated leukocyte migration

There is a growing body of evidence that bilirubin, which is generated during the physiological breakdown of heme, exerts potent anti-inflammatory effects. Previous work by our group suggests that bilirubin is able to suppress inflammatory responses by preventing the migration of leukocytes into target tissues through disruption of vascular cell adhesion molecule-1 (VCAM-1)-dependent cell signaling. As VCAM-1 is an important mediator of tissue injury in the dextran sodium sulfate (DSS) murine model of inflammatory colitis, we examined whether bilirubin prevents colonic injury in DSS-treated mice. As anticipated, bilirubin-treated animals manifested significantly less colonic injury and reduced infiltration of inflammatory cells into colon tissues. We further observed that bilirubin administration was associated with a reduced number of eosinophils and monocytes in the small intestine, with a corresponding increase in peripheral blood eosinophilia, regardless of whether mice received DSS. These findings suggest that bilirubin impairs the normal migration of eosinophils into intestinal tissues, as supported by in vitro experiments showing that bilirubin blocks the VCAM-1-dependent movement of Jurkat cells across human endothelial cell monolayers. Taken together, our findings support that bilirubin ameliorates DSS-induced colitis and disrupts the physiological trafficking of leukocytes to the intestine by preventing transmigration across the vascular endothelium, potentially through the inhibition VCAM-1-mediated signaling. Our findings raise the possibility that bilirubin functions as an endogenous regulator of inflammatory responses.

Bilirubin prevents acute DSS-induced colitis by inhibiting leukocyte infiltration and suppressing upregulation of inducible nitric oxide synthase

Bilirubin is thought to exert anti-inflammatory effects by inhibiting vascular cell adhesion molecule-1 (VCAM-1)-dependent leukocyte migration and by suppressing the expression of inducible nitric oxide synthase (iNOS). As VCAM-1 and iNOS are important mediators of tissue injury in the dextran sodium sulfate (DSS) murine model of inflammatory colitis, we examined whether bilirubin prevents colonic injury in DSS-treated mice. Male C57BL/6 mice were administered 2.5% DSS in the drinking water for 7 days, while simultaneously receiving intraperitoneal injections of bilirubin (30 mg/kg) or potassium phosphate vehicle. Disease activity was monitored, peripheral blood counts and serum nitrate levels were determined, and intestinal specimens were analyzed for histological injury, leukocyte infiltration, and iNOS expression. The effect of bilirubin on IL-5 production by HSB-2 cells and on Jurkat cell transendothelial migration also was determined. DSS-treated mice that simultaneously received bilirubin lost less body weight, had lower serum nitrate levels, and exhibited reduced disease severity than vehicle-treated animals. Concordantly, histopathological analyses revealed that bilirubin-treated mice manifested significantly less colonic injury, including reduced infiltration of eosinophils, lymphocytes, and monocytes, and diminished iNOS expression. Bilirubin administration also was associated with decreased eosinophil and monocyte infiltration into the small intestine, with a corresponding increase in peripheral blood eosinophilia. Bilirubin prevented Jurkat migration but did not alter IL-5 production. In conclusion, bilirubin prevents DSS-induced colitis by inhibiting the migration of leukocytes across the vascular endothelium and by suppressing iNOS expression.

Osteopontin knockout does not influence the severity of rectal damage in a preclinical model of radiation proctitis in mice

BACKGROUND

Radiation damage to the normal gut is a dose-limiting factor in the application of radiation therapy to treat abdominal and pelvic cancers. All tissue cell types react in concert to orchestrate an acute inflammatory reaction followed by a delayed chronic scarring process. Osteopontin (OPN) is a matricellular protein known to be involved in various physiological but also pathological processes such as tissue inflammation and fibrosis.

AIMS

The aim of our study was to determine whether OPN knockout influences the severity of radiation proctitis and to investigate the role of OPN in the development of radiation-induced gut damage.

RESULTS

Here we show that human radiation proctitis is associated with increased immunostaining of the intracellular and extracellular/matrix-linked isoforms of OPN. Moreover, endothelial cells in vitro and rectal tissue in a preclinical model of radiation proctitis in mice both respond to radiation exposure by a sustained increase in OPN mRNA and protein levels. Genetic deficiency of OPN did not influence radiation-induced rectal damage and was associated with significantly decreased animal survival. The acute and late radiation injury scores were similar in OPN-null mice compared with their control littermates.

CONCLUSION

This study shows that in our model and given the pleiotropic actions of OPN in tissue inflammation and fibrosis, further studies are necessary to understand the precise roles of OPN in radiation-induced proctitis and to determine whether OPN is a useful therapeutic tool in prevention of radiation-induced intestinal tissue injury.

Control of CD8 T-Cell Infiltration into Tumors by Vasculature and Microenvironment

CD8 T-cells are a critical brake on the initial development of tumors. In established tumors, the presence of CD8 T-cells is correlated with a positive patient prognosis, although immunosuppressive mechanisms limit their effectiveness and they are rarely curative without manipulation. Cancer immunotherapies aim to shift the balance back to dominant antitumor immunity through antibody blockade of immunosuppressive signaling pathways, vaccination, and adoptive transfer of activated or engineered T-cells. These approaches have yielded striking responses in small subsets of patients with solid tumors, most notably those with melanoma. Importantly, the subset of patients who respond to vaccination or immunosuppression blockade therapies are those with CD8 T-cells present in the tumor prior to initiating therapy. While current adoptive cell therapy approaches can be dramatically effective, they require infusion of extremely large numbers of T-cells, but the number that actually infiltrates the tumor is very small. Thus, poor representation of CD8 T-cells in tumors is a fundamental hurdle to successful immunotherapy, over and above the well-established barrier of immunosuppression. In this review, we discuss the factors that determine whether immune cells are present in tumors, with a focus on the representation of cytotoxic CD8 T-cells. We emphasize the critically important role of tumor-associated vasculature as a gateway that enables the active infiltration of both effector and naïve CD8 T-cells that exert antitumor activity. We also discuss strategies to enhance the gateway function and extend the effectiveness of immunotherapies to a broader set of cancer patients.

New model for long-term investigations of cutaneous microcirculatory and inflammatory changes following irradiation

Radiotherapy is used for curative and palliative treatment. However, its negative effect on normal tissue is a limiting factor for the deliverable dose. Microcirculatory breakdown and prolonged inflammation in particular are major features of late side effects. The purpose of this study was to develop a reliable animal model that will allow a long-term in vivo analysis of microcirculation and inflammation following irradiation. A single dose of 90 Gy was delivered to the ears of hairless mice (n = 15). Intravital fluorescent microscopy was used to assess microcirculatory parameters and leukocyte behaviour. Values for the identical (control) areas were obtained before as well as during the following days, weeks and months following irradiation. The arteriolar and venular diameter increased up to Day 14, decreased during the following months, and increased again after one year. The red blood cell velocity increased up to 145% on Day 3, decreased on Day 7 to 115%, and stayed above baseline value the whole year. The integrity loss of the endothelium increased up to Day 7 and continued up to Day 75 after radiation. After one year, the oedema was at the baseline level. Leukocytes showed their maximal activity at one year after trauma. An increase was measured up to Day 25; the lowest values were measured at Day 40 post-irradiation, followed by a repeated increase. The present model allows a certain visualization of microcirculatory disturbances and inflammation over a period of months. This permits the possibility of long-term investigations of the underlying pathophysiology following irradiation, including possible drug interactions.

Low-dose irradiation affects expression of inflammatory markers in the heart of ApoE -/- mice

Epidemiological studies indicate long-term risks of ionizing radiation on the heart, even at moderate doses. In this study, we investigated the inflammatory, thrombotic and fibrotic late responses of the heart after low-dose irradiation (IR) with specific emphasize on the dose rate. Hypercholesterolemic ApoE-deficient mice were sacrificed 3 and 6 months after total body irradiation (TBI) with 0.025, 0.05, 0.1, 0.5 or 2 Gy at low (1 mGy/min) or high dose rate (150 mGy/min). The expression of inflammatory and thrombotic markers was quantified in frozen heart sections (CD31, E-selectin, thrombomodulin, ICAM-1, VCAM-1, collagen IV, Thy-1, and CD45) and in plasma samples (IL6, KC, MCP-1, TNFα, INFγ, IL-1β, TGFβ, INFγ, IL-10, sICAM-1, sE-selectin, sVCAM-1 and fibrinogen) by fluorescence analysis and ELISA. We found that even very low irradiation doses induced adaptive late responses, such as increases of capillary density and changes in collagen IV and Thy-1 levels indicating compensatory regulation. Slight decreases of ICAM-1 levels and reduction of Thy 1 expression at 0.025–0.5 Gy indicate anti-inflammatory effects, whereas at the highest dose (2 Gy) increased VCAM-1 levels on the endocardium may represent a switch to a pro-inflammatory response. Plasma samples partially confirmed this pattern, showing a decrease of proinflammatory markers (sVCAM, sICAM) at 0.025–2.0 Gy. In contrast, an enhancement of MCP-1, TNFα and fibrinogen at 0.05–2.0 Gy indicated a proinflammatory and prothrombotic systemic response. Multivariate analysis also revealed significant age-dependent increases (KC, MCP-1, fibrinogen) and decreases (sICAM, sVCAM, sE-selectin) of plasma markers. This paper represents local and systemic effects of low-dose irradiation, including also age- and dose rate-dependent responses in the ApoE^-/- mouse model. These insights in the multiple inflammatory/thrombotic effects caused by low-dose irradiation might facilitate an individual evaluation and intervention of radiation related, long-term side effects but also give important implications for low dose anti-inflammatory radiotherapy.

Late inflammatory and thrombotic changes in irradiated hearts of C57BL/6 wild-type and atherosclerosis-prone ApoE-deficient mice

BACKGROUND AND PURPOSE

Radiation-induced heart disease represents a late complication of thoracic radiotherapy. We investigated the inflammatory and thrombotic response after local heart irradiation in wild-type and atherosclerosis-prone mice.

MATERIAL AND METHODS

Atherosclerosis-prone ApoE(-/-) and C57BL/6 wild-type mice were sacrificed 20, 40, and 60 weeks after irradiation with 0.2, 2, 8, or 16 Gy. The expression of CD31, vascular cell adhesion molecule-1 (VCAM-1), thrombomodulin (TM), and CD45 were quantified by immunofluorescence staining of heart tissue sections.

RESULTS

Microvascular density decreased at 40 weeks after 16 Gy in C57BL/6 but not in ApoE(-/-) mice. CD31 expression declined in C57BL/6 mice at 40 weeks (8 Gy), but increased in ApoE(-/-) mice at 20 (2/8/16 Gy) and 60 weeks (16 Gy). Capillary area decreased in C57BL/6 at 40 weeks (8/16 Gy) but increased in ApoE(-/-) mice at 20 weeks (16 Gy). Endocardial VCAM-1 expression remained unchanged. TM-positive capillaries decreased at 40 weeks (8/16 Gy) in C57BL/6 and at 60 weeks (2/16 Gy) in ApoE(-/-) mice. Leukocyte infiltration transiently rose 40 weeks after 8 Gy (only ApoE(-/-)) and 16 Gy. After receiving a low irradiation dose of 0.2 Gy, no significant changes were observed in any of the mouse models.

CONCLUSION

This study demonstrated that local heart irradiation affects microvascular structure and induces inflammatory/thrombotic responses in mice in a dose- and time-dependent manner. Thereby, significant prothrombotic changes were found in both strains, although they were progressive in ApoE(-/-) mice only. Proinflammatory responses, like the increase of adhesion molecules and leukocyte infiltration, were more pronounced and occurred at lower doses in ApoE(-/-) vs. C57BL/6 mice. These findings indicate that metabolic risk factors, such as decreased ApoE lipoproteins, may lead to an enhanced proinflammatory and prothrombotic late response in locally irradiated hearts.

Enhanced and aberrant T cell trafficking following total body irradiation: a gateway to graft-versus-host disease?

Pre-transplant conditioning regimens play a major role in triggering graft-versus-host disease (GVHD). This study investigated the effect of irradiation on donor T cell trafficking to lymphoid and non-lymphoid tissues by comparing the migration of carboxy-fluorescein diacetate succinimidyl ester-labelled, naïve donor T lymphocytes in vivo in irradiated and non-irradiated syngeneic mice recipients. Recruitment of adoptively transferred naïve T cells to secondary lymphoid organs was increased in irradiated mice and naïve T cells also aberrantly localized to non-lymphoid tissues. Irradiation also induced aberrant effector memory T cell migration into lymph nodes and their localization to homing-privileged non-lymphoid sites, such as the gut. The presence of a minor histocompatibility mismatch further enhanced the aberrant accumulation of T cells in both lymphoid and non-lymphoid tissue, whilst their migratory pattern was not modified as compared to fully matched irradiated recipients. These effects correlated with decreased permeability of, and the secretion of chemotactic factors by the endothelium. Our findings are consistent with the possibility that excessive, dysregulated extravasation of T cells induced by irradiation promotes the development of GVHD.

Irradiation induces different inflammatory and thrombotic responses in carotid arteries of wildtype C57BL/6J and atherosclerosis-prone ApoE(-/-) mice

BACKGROUND AND PURPOSE

We have previously shown that irradiation to the carotid arteries of hypercholesterolemic ApoE(-/-) mice accelerated the development of macrophage-rich, inflammatory atherosclerotic lesions. We now investigated the mechanism underlying the development of radiation-induced atherosclerosis.

MATERIALS AND METHODS

ApoE(-/-) and wildtype C57BL/6J mice received 0, 8 or 14 Gy to the neck and the carotid arteries were harvested 1 day, 1 or 4 weeks later. Immunohistochemical stainings were performed to evaluate well-known inflammatory and thrombotic molecules. A hypothesis-generating approach was used to compare gene expression profiles of irradiated and unirradiated carotid arteries.

RESULTS

Basal levels of endothelial VCAM-1 and thrombomodulin immunoexpression were higher in ApoE(-/-) mice than in C57BL/6J mice. At 1 week after 14 Gy VCAM-1 immunoexpression was decreased in ApoE(-/-) mice, whereas ICAM-1 immunoexpression was decreased at 1 and 4 weeks after 14 Gy in C57BL/6J mice. Thrombomodulin and tissue factor immunoexpression were elevated at 4 weeks after 14 Gy in ApoE(-/-) mice and reduced in C57BL/6J mice. There were no changes in immunoexpression of eNOS, MCP-1 or endoglin. Several canonical pathways were differentially expressed after irradiation, including tight junction pathways, leukocyte extravasation signaling and PI3K/AKT signaling.

CONCLUSION

ApoE(-/-) and C57BL/6J mice respond differently to irradiation. The thrombotic pathways were activated after irradiation in ApoE(-/-) mice only. Genes involved in tight junction regulation were up-regulated in ApoE(-/-) mice and decreased in C57BL/6J mice. These factors may have contributed to fatty-streak formation in ApoE(-/-) mice.

Inflammation and immunity in radiation damage to the gut mucosa

Erythema was observed on the skin of the first patients treated with radiation therapy. It is in particular to reduce this erythema, one feature of tissue inflammation, that prescribed dose to the tumor site started to be fractionated. It is now well known that radiation exposure of normal tissues generates a sustained and apparently uncontrolled inflammatory process. Radiation-induced inflammation is always observed, often described, sometimes partly explained, but still today far from being completely understood. The thing with the gut and especially the gut mucosa is that it is at the frontier between the external milieu and the organism, is in contact with a plethora of commensal and foreign antigens, possesses a dense-associated lymphoid tissue, and is particularly radiation sensitive because of a high mucosal turnover rate. All these characteristics make the gut mucosa a strong responsive organ in terms of radiation-induced immunoinflammation. This paper will focus on what has been observed in the normal gut and what remains to be done concerning the immunoinflammatory response following localized radiation exposure.

The role of alveolar epithelium in radiation-induced lung injury

Pneumonitis and fibrosis are major lung complications of irradiating thoracic malignancies. In the current study, we determined the effect of thoracic irradiation on the lungs of FVB/N mice. Survival data showed a dose-dependent increase in morbidity following thoracic irradiation with single (11–13 Gy) and fractionated doses (24–36 Gy) of ¹³⁷Cs γ-rays. Histological examination showed a thickening of vessel walls, accumulation of inflammatory cells, collagen deposition, and regional fibrosis in the lungs 14 weeks after a single 12 Gy dose and a fractionated 30 Gy dose; this damage was also seen 5 months after a fractionated 24 Gy dose. After both single and fractionated doses, i] aquaporin-5 was markedly decreased, ii] E-cadherin was reduced and iii] prosurfactant Protein C (pro-SP-c), the number of pro-SP-c⁺ cells and vimentin expression were increased in the lungs. Immunofluorescence analysis revealed co-localization of pro-SP-c and α-smooth muscle actin in the alveoli after a single dose of 12 Gy. These data suggest that, i] the FVB/N mouse strain is sensitive to thoracic radiation ii] aquaporin-5, E-cadherin, and pro-SP-c may serve as sensitive indicators of radiation-induced lung injury; and iii] the epithelial-to-mesenchymal transition may play an important role in the development of radiation-induced lung fibrosis.

Alteration of the inflammatory molecule network after irradiation of soft tissue

Inflammatory molecules (IMs) play an important role in ionizing radiation (IR)-induced soft tissue damage. The alteration of IMs as a function of time was studied with a protein array containing 62 IMs in mouse cutaneous soft tissues exposed to 30 Gy. The results showed that: (1) 2 days after irradiation, the levels of TGF-β1, MIP-1γ, IL-1α, and sTNF RI increased, while IGFBP-3, CXCL16, and IL-1β decreased in IR skin as compared to control skin; (2) 21 days after IR, TGF-β1, and MIP-1 γ, IL-1α remained high, while CXCL16 and IL-1β remained low; (3) 3 months after IR, the cytokine pattern exhibited reversals. The levels of MIP-1γ decreased, while VCAM-1, IGFBP-3, and TGF-β1 production increased. The data indicated that: (a) IMs change as a function of time after soft tissue irradiation; (b) changing IM levels may reflect the altered balance of the cytokine network, leading to imbalance or homeostasis; and (c) an antibody-based protein array can be used to assess multiple IMs simultaneously, making it useful for bulk screening for changes in tissue cytokine levels.

Radiation as a risk factor for cardiovascular disease

Abstract population are ubiquitous background radiation and medical exposure of patients. From the early 1980s to 2006, the average dose per individual in the United States for all sources of radiation increased by a factor of 1.7-6.2 mSv, with this increase due to the growth of medical imaging procedures. Radiation can place individuals at an increased risk of developing cardiovascular disease. Excess risk of cardiovascular disease occurs a long time after exposure to lower doses of radiation as demonstrated in Japanese atomic bomb survivors. This review examines sources of radiation (atomic bombs, radiation accidents, radiological terrorism, cancer treatment, space exploration, radiosurgery for cardiac arrhythmia, and computed tomography) and the risk for developing cardiovascular disease. The evidence presented suggests an association between cardiovascular disease and exposure to low-to-moderate levels of radiation, as well as the well-known association at high doses. Studies are needed to define the extent that diagnostic and therapeutic radiation results in increased risk factors for cardiovascular disease, to understand the mechanisms involved, and to develop strategies to mitigate or treat radiation-induced cardiovascular disease.

Cardiovascular disease associated with radiotherapy: activation of nuclear factor kappa-B

There have been several recent reports of an increased risk of cardiovascular disease after radiotherapy. Hence, with an increasing number of cancer survivors, the incidence of cardiovascular disease caused by radiotherapy will increase. The existence of a type of vascular disease, or vasculopathy, induced by radiotherapy has been known for decades. It is important to identify and understand the molecular causes of this vasculopathy to determine preventive strategies. Recently, a chronic inflammation with similarities to atherosclerosis has been observed, with activation of the transcription factor nuclear factor kappa-B (NF-κB) as a possible cause. However, the trigger for NF-κB activation is unclear although it may be that reactive oxygen species or direct DNA damage is involved. To minimize the risk of cardiovascular disease in vulnerable patients, careful selection of patients, radiation dose and fractionation are important, together with the development of new techniques that reduce radiation dose to the blood vessels. In the light of the finding of an interaction between risk factors for cardiovascular disease and radiotherapy, it is reasonable to modify these factors including diabetes mellitus, hyperlipidaemia, hypertension and smoking. We believe that preventive strategies focusing on NF-κB can reduce the risk of future adverse cardiovascular events.

Radiation-induced ICAM-1 expression via TGF-β1 pathway on human umbilical vein endothelial cells; comparison between X-ray and carbon-ion beam irradiation

Adhesion of inflammatory cells to endothelial cells is considered to be involved in the process of radiation-induced damage and fibrosis. Intercellular adhesion molecule-1 (ICAM-1) and transforming growth factor-beta1 (TGF-β1) are thought to play important roles in this process. In this study, radiation-induced ICAM-1 expression on endothelial cells was investigated with the use of an inhibitor of TGF-β1 receptor kinase (SB431542) and the effects of X-ray and carbon-ion beam were compared. Cell cultures of human umbilical vein endothelial cells (HUVE cells) were incubated with TGF-β1 and irradiated with 140 KV X-ray. Next, HUVE cells were irradiated with X-ray and 220 MeV carbon-ion beam with or without SB431542. Immunofluorescence analysis was used to quantify ICAM-1 expression. The expression of ICAM-1 on HUVE cells was significantly increased by the stimulation with TGF-β1. Expression of ICAM-1 was increased by X-ray and carbon-ion beam irradiation and decreased significantly with SB431542 after both irradiations. The expression of ICAM-1 by 2 Gy of carbon-ion beam irradiation was 6.7 fold higher than that of non-irradiated cells, while 5 Gy of X-ray irradiation increased the expression of ICAM-1 by 2.5 fold. According to ICAM-1 expression, the effect of carbon-ion beam irradiation was about 2.2, 4.4 and 5.0 times greater than that of the same doses of X-ray irradiation (1, 2 and 5 Gy, respectively). The present results suggested that radiation-induced ICAM-1 expression on HUVE cells was, at least partially, regulated by TGF-β1. Carbon-ion beam induced significantly higher ICAM-1 expression than X-ray.

Expression of Endothelial Adhesion Molecules After Radiosurgery in an Animal Model of Arteriovenous Malformation

BACKGROUND:

Endothelial adhesion molecules may be important in the response of brain arteriovenous malformations (AVMs) to radiosurgery. In addition to a putative role in the occlusive process after radiosurgery, they may serve as potential targets for biological strategies to accelerate intravascular thrombosis.

OBJECTIVE:

To determine the temporal expression of E-selectin and vascular cell adhesion molecule-1 in an animal model of AVMs.

METHODS:

Forty-one Sprague-Dawley rats underwent surgical creation of a carotid-to-jugular anastomosis. Radiosurgery (25 Gy) was delivered to the model “nidus” after 6 weeks, and the tissue was harvested 1 to 84 days after radiosurgery. Control groups received sham irradiation. Immunofluorescence was used to study the expression of E-selectin and vascular cell adhesion molecule-1.

RESULTS:

Endothelial E-selectin expression was limited to regions receiving radiosurgery. E-selectin expression reached maximal expression at 24 hours after radiosurgery and was sustained for another 24 hours before gradually reducing to baseline at 84 days post-radiosurgery (P &lt; .01). Vascular cell adhesion molecule-1 expression remained at the baseline level for the first week; a 50% increase was observed at 21 days after radiosurgery, which was sustained for another 3 weeks before returning to the baseline at 84 days after radiosurgery (P &lt; .05).

CONCLUSION:

Radiosurgery stimulates early expression of E-selectin and delayed up-regulation of vascular cell adhesion molecule-1 on the endothelial surface of the AVM model nidus. Cell adhesion molecule expression may play an important role in the process leading to vascular obliteration after irradiation. These molecular alterations may be harnessed to promote thrombosis in the irradiated vasculature using a vascular targeting agent.

[Reirradiation of normal tissues: preclinical radiobiological data]

Reirradiation represent an unfrequent particular clinical situation. The risk/benefit ratio assessment must be taken into account, considering both clinical and dosimetric aspects. There is a relatively limited amount of preclinical data available to date and clinicians should cautiously perform reirradiations in selected indications. This review summarizes the experimental data available on reirradiation of normal tissues, the consequences on early and late toxicities as well as the intrinsic limitations of these models.

Sustained inflammation due to nuclear factor-kappa B activation in irradiated human arteries

OBJECTIVES

The aim of this study was to investigate gene expression networks related to cardiovascular disease in radiated human arteries.

BACKGROUND

Recent epidemiological studies have shown that radiotherapy is associated with cardiovascular disease years after treatment. However, the molecular mechanisms underlying late effects of radiation are poorly described.

METHODS

Arterial biopsies from radiated and nonradiated human conduit arteries, from the same patient, were simultaneously harvested during microvascular free tissue transfer for cancer-reconstruction in 13 patients, 4 to 500 weeks from radiation treatment. Radiated and nonradiated arteries were compared, with Affymetrix (Santa Clara, California) microarrays on a subset of the material to generate candidate genes. A Taqman (Applied Biosystems, Foster City, California) low-density array of 45 selected genes was designed for analysis of the whole material.

RESULTS

Thirteen genes were synchronously expressed in all patients (p = 0.0015), including CCL8, CCL3, CXCL2, DUSP5, FGFR2, HMOX1, HOXA9, IL-6, MMP-1, PTX3, RDH10, SOD2, and TNFAIP3. A majority of differentially regulated genes related to the nuclear factor-kappa B (NF-kappaB) signaling pathway and were dysregulated even years after radiation. The NF-kappaB activation was confirmed by immunohistochemistry and immunofluorescence.

CONCLUSIONS

In the present study, we found sustained inflammation due to NF-kappaB activation in human radiated arteries. The results are supported by previous in vitro findings suggesting that deoxyribonucleic acid injury, after radiation, activates NF-kappaB. We also suggest that HOXA9 might be involved in the regulation of NF-kappaB activation. The observed sustained inflammatory response can explain cardiovascular disease years after radiation.

Microbial influences on the small intestinal response to radiation injury

PURPOSE OF REVIEW

Injury to the small bowel from ionizing radiation occurs commonly in patients undergoing cancer therapy and less commonly in instances of accidental radiation overexposure. Several lines of evidence now suggest that dynamic interactions between the host's enteric microbiota and innate immune system are important in modulating the intestinal response to radiation. Here, we will review recent developments in the area of acute radiation enteropathy and examine the current state of knowledge regarding the impact of host-microbial interactions in the process.

RECENT FINDINGS

There is promise in the development and testing of new clinical biomarkers including serum citrulline. Toll-like receptor agonists and innate immune system signaling pathways including nuclear factor-kappa B profoundly alter intestinal epithelial cell apoptosis and crypt survival after radiation exposure. Germ-free conditions, probiotics and antibiotics are each identified as modifiers of disease development and course. A human study suggested that luminal microbiota composition may influence the host's intestinal response to radiation and may change in those developing postradiation diarrhea.

SUMMARY

New knowledge implies that investigations aimed at deciphering the microbiome-host interactions before and after small bowl radiation injury may eventually allow prediction of disease course and offer opportunities for the development of novel therapeutic or prophylactic strategies.

Effect of irradiation on gene expression of rat liver adhesion molecules: in vivo and in vitro studies

BACKGROUND AND PURPOSE

Migration of leukocytes into tissue is a key element of innate and adaptive immunity. An animal study showed that liver irradiation, in spite of induction of chemokine gene expression, does not lead to recruitment of leukocytes into the parenchyma. The aim of this study was to analyze gene expression of adhesion molecules, which mediate leukocyte recruitment into organs, in irradiated rat liver in vivo and rat hepatocytes in vitro.

MATERIAL AND METHODS

Rat livers in vivo were irradiated selectively at 25 Gy. Isolated hepatocytes in vitro were irradiated at 8 Gy. RNA extracted within 48 h after irradiation in vivo and in vitro was analyzed by real-time PCR (polymerase chain reaction) and Northern blot. Adhesion molecule concentration in serum was measured by ELISA (enzyme-linked immunosorbent assay). Cryostat sections of livers were used for immunohistology.

RESULTS

Significant radiation-induced increase of ICAM-1 (intercellular adhesion molecule-1), VCAM-1 (vascular cell adhesion molecule-1), JAM-1 (junctional adhesion molecule-1), beta1-integrin, beta2-integrin, E-cadherin, and P-selectin gene expression could be detected in vivo, while PECAM-1 (platelet-endothelial cell adhesion molecule-1) gene expression remained unchanged. In vitro, beta1-integrin, JAM-1, and ICAM-2 showed a radiation-induced increased expression, whereas the levels of P-selectin, ICAM-1, PECAM-1, VCAM-1, Madcam-1 (mucosal addressin cell adhesion molecule-1), beta2-integrin, and E-cadherin were downregulated. However, incubation of irradiated hepatocytes with either tumor necrosis factor-(TNF-)alpha, interleukin-(IL-)1beta, or IL-6 plus TNF-alpha led to an upregulation of P-selectin, ICAM-1 and VCAM-1.

CONCLUSION

The findings suggest that liver irradiation modulates gene expression of the main adhesion molecules in vivo and in cytokine-activated hepatocytes, with the exception of PECAM-1. This may be one reason for the lack of inflammation in the irradiated rat liver.

Cell carriers for oncolytic viruses: Fed Ex for cancer therapy

Oncolytic viruses delivered directly into the circulation face many hazards that impede their localization to, and infection of, metastatic tumors. Such barriers to systemic delivery could be overcome if couriers, which confer both protection, and tumor localization, to their viral cargoes, could be found. Several preclincal studies have shown that viruses can be loaded into, or onto, different types of cells without losing the biological activity of either virus or cell carrier. Importantly, such loading can significantly protect the viruses from immune-mediated virus-neutralizing activities, including antiviral antibody. Moreover, an impressive portfolio of cellular vehicles, which have some degree of tropism for tumor cells themselves, or for the biological properties associated with the tumor stroma, is already available. Therefore, it will soon be possible to initiate clinical protocols to test the hypopthesis that cell-mediated delivery can permit efficient shipping of oncolytic viruses from the loading bay (the production laboratory) directly to the tumor in immune-competent patients with metastatic disease.

[Radiotherapy: what therapeutic orientations against the digestive aftereffects?]

Despite constant progress in radiotherapy techniques such as tumour imaging and cartography, techniques of radiation delivery or fractionation schedules, damage to normal gastro-intestinal tissues is inevitably associated with radiation therapy of pelvic tumours. Acute radiation enteritis concerns 80% of patients. It is related to stem cell loss, default in epithelial regenerating capacity and inflammation-induced mucosal dystrophy and ulceration. Chronic injury may develop in 5 to 10% of patients and is characterized by intestinal wall fibrosis resulting from an exaggerated scarring process, chronic inflammation and tissue necrosis. Research in mechanistic processes of normal tissue damage paved the way for new therapeutic approaches to emerge. These new targets include mucosal regeneration, reduction of vascular activation, inflammation and thrombosis, and fight against mesenchymal cells sustained activation. Effective strategies are multiple on preclinical models, but numerous efforts have to be made to achieve the complicated goal of protection of normal tissues from the side effects of radiation therapy.