[Role of endothelium in radiation-induced normal tissue damages]

Inflammatory cells dynamics control neovascularization and tissue healing after localized radiation induced injury in mice

Local overexposure to ionizing radiation leads to chronic inflammation, vascular damage and cachexia. Here we investigate the kinetics of inflammatory cells from day (D)1 to D180 after mouse hindlimb irradiation and analyze the role of monocyte (Mo) subsets in tissue revascularization. At D1, we find that Mo and T cells are mobilized from spleen and bone marrow to the blood. New vessel formation during early phase, as demonstrated by ~1.4- and 2-fold increased angiographic score and capillary density, respectively, correlates with an increase of circulating T cells, and Mo^hi and type 1-like macrophages in irradiated muscle. At D90 vascular rarefaction and cachexia are observed, associated with decreased numbers of circulating Mo^lo and Type 2-like macrophages in irradiated tissue. Moreover, CCR2- and CX3CR1-deficency negatively influences neovascularization. However adoptive transfer of Mo^hi enhances vessel growth. Our data demonstrate the radiation-induced dynamic inflammatory waves and the major role of inflammatory cells in neovascularization.

Prostate Cancer Survivors Present Long-Term, Residual Systemic Immune Alterations

Simple Summary

The development of cancer is very often accompanied by systemic immune alterations which can be further aggravated by major anti-cancer therapies. However, there is very little known about how long these alterations persist in patients successfully cured of cancer. The aim of our work was to investigate how cancer and radiotherapy as major anti-cancer treatment modalities impact the immune system long after the successful treatment of a tumor. We investigated prostate cancer patients treated with a special form of radiotherapy (low-dose rate brachytherapy) often used for the treatment of prostate cancer and followed a wide range of immune parameters at regular intervals up to 3 years after the start of the treatment. Our results showed that some immune alterations did not recover after the treatment of the disease, on the contrary, they persisted, and in some cases got even worse. Further studies are needed to explain the causes and the potential long-term consequences of these alterations.

Abstract

Background: The development of cancer and anti-tumor therapies can lead to systemic immune alterations but little is known about how long immune dysfunction persists in cancer survivors. Methods: We followed changes in the cellular immune parameters of prostate cancer patients with good prognostic criteria treated with low dose rate brachytherapy before and up to 3 years after the initiation of therapy. Results: Patients before therapy had a reduced CD4+ T cell pool and increased regulatory T cell fraction and these alterations persisted or got amplified during the 36-month follow-up. A significant decrease in the total NK cell number and a redistribution of the circulating NK cells in favor of a less functional anergic subpopulation was seen in patients before therapy but tumor regression led to the regeneration of the NK cell pool and functional integrity. The fraction of lymphoid DCs was increased in patients both before therapy and throughout the whole follow-up. Increased PDGF-AA, BB, CCL5 and CXCL5 levels were measured in patients before treatment but protein levels rapidly normalized. Conclusions: while NK cell dysfunction recovered, long-term, residual alterations persisted in the adaptive and partly in the innate immune system.

The Relationship Between Cancer and Functional and Structural Markers of Subclinical Atherosclerosis: A Systematic Review and Meta-Analysis

Objectives

The relationship between cancer and subclinical atherosclerosis has always been the focus of people's attention. We conducted a systematic review and meta-analysis by evaluating the effects of cancer on functional and structural markers of subclinical atherosclerosis:intima-media thickness (IMT), pulse wave velocity (PWV), and flow-mediated vasodilation (FMD).

Methods

A comprehensive and systematic literature search was conducted on the internet. Sensitivity analysis, publication bias, standard mean difference (SMD), corresponding 95% confidence interval (95% CI), and subgroup analysis were performed for all relevant research indicators in the retrieved literature.

Results

Forty-six studies were included, including 3,729 cancer patients and 2,404 healthy controls. Cancer patients had significantly thicker IMT [SMD (95%CI) = 0.290 (0.069 to 0.511), P = 0.010] and higher PWV [SMD (95%CI) = 0.392 (0.136 to 0.647), P = 0.003] compared with healthy controls. There was no significant difference in FMD [SMD (95% CI) = −0.192 (−0.527 to 0.144), P > 0.05). After subgrouping by age, male proportion, and treatment, the analysis results of IMT ≥ 50 years old, PWV and FMD < 50 years old, male proportion ≥50%, chemotherapy group, IMT and PWV radiotherapy group, and PWV endocrine therapy group were statistically significant (P < 0.05). There were no significant differences in other subgroup analyses, overall sensitivity analysis, and publication bias (p < 0.05).

Conclusions

Cancer may promote subclinical atherosclerosis, and change the functional and structural markers of subclinical atherosclerosis such as IMT and PWV. Early intervention and prevention should be pursued.

Understanding Molecular Mechanisms and Identifying Key Processes in Chronic Radiation Cystitis

Chronic radiation cystitis (CRC) is a consequence of pelvic radiotherapy and affects 5–10% of patients. The pathology of CRC is without curative treatment and is characterized by incontinence, pelvic pain and hematuria, which severely degrades patients’ quality of life. Current management strategies rely primarily on symptomatic measures and have certain limitations. Thanks to a better understanding of the pathophysiology of radiation cystitis, studies targeting key manifestations such as inflammation, neovascularization and cell atrophy have emerged and are promising avenues for future treatment. However, the mechanisms of CRC are still better described in animal models than in human models. Preclinical studies conducted to elucidate the pathophysiology of CRC use distinct models and are most often limited to specific processes, such as fibrosis, vascular damage and inflammation. This review presents a synthesis of experimental studies aimed at improving our understanding of the molecular mechanisms at play and identifying key processes in CRC.

Inhibition of EphA2 by Dasatinib Suppresses Radiation-Induced Intestinal Injury

Radiation-induced multiorgan dysfunction is thought to result primarily from damage to the endothelial system, leading to a systemic inflammatory response that is mediated by the recruitment of leukocytes. The Eph–ephrin signaling pathway in the vascular system participates in various disease developmental processes, including cancer and inflammation. In this study, we demonstrate that radiation exposure increased intestinal inflammation via endothelial dysfunction, caused by the radiation-induced activation of EphA2, an Eph receptor tyrosine kinase, and its ligand ephrinA1. Barrier dysfunction in endothelial and epithelial cells was aggravated by vascular endothelial–cadherin disruption and leukocyte adhesion in radiation-induced inflammation both in vitro and in vivo. Among all Eph receptors and their ligands, EphA2 and ephrinA1 were required for barrier destabilization and leukocyte adhesion. Knockdown of EphA2 in endothelial cells reduced radiation-induced endothelial dysfunction. Furthermore, pharmacological inhibition of EphA2–ephrinA1 by the tyrosine kinase inhibitor dasatinib attenuated the loss of vascular integrity and leukocyte adhesion in vitro. Mice administered dasatinib exhibited resistance to radiation injury characterized by reduced barrier leakage and decreased leukocyte infiltration into the intestine. Taken together, these data suggest that dasatinib therapy represents a potential approach for the protection of radiation-mediated intestinal damage by targeting the EphA2–ephrinA1 complex.

Pravastatin Alleviates Radiation Proctitis by Regulating Thrombomodulin in Irradiated Endothelial Cells

Although radiotherapy plays a crucial in the management of pelvic tumors, its toxicity on surrounding healthy tissues such as the small intestine, colon, and rectum is one of the major limitations associated with its use. In particular, proctitis is a major clinical complication of pelvic radiotherapy. Recent evidence suggests that endothelial injury significantly affects the initiation of radiation-induced inflammation. The damaged endothelial cells accelerate immune cell recruitment by activating the expression of endothelial adhesive molecules, which participate in the development of tissue damage. Pravastatin, a cholesterol lowering drug, exerts persistent anti-inflammatory and anti-thrombotic effects on irradiated endothelial cells and inhibits the interaction of leukocytes and damaged endothelial cells. Here, we aimed to investigate the effects of pravastatin on radiation-induced endothelial damage in human umbilical vein endothelial cell and a murine proctitis model. Pravastatin attenuated epithelial damage and inflammatory response in irradiated colorectal lesions. In particular, pravastatin improved radiation-induced endothelial damage by regulating thrombomodulin (TM) expression. In addition, exogenous TM inhibited leukocyte adhesion to the irradiated endothelial cells. Thus, pravastatin can inhibit endothelial damage by inducing TM, thereby alleviating radiation proctitis. Therefore, we suggest that pharmacological modulation of endothelial TM may limit intestinal inflammation after irradiation.

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.

Endothelial Hey2 deletion reduces endothelial-to-mesenchymal transition and mitigates radiation proctitis in mice

The current study evaluated the role of Hey2 transcription factor in radiation-induced endothelial-to-mesenchymal transition (EndoMT) and its impact on radiation-induced tissue damage in mice. Phenotypic modifications of irradiated, Hey2 siRNA- and Hey2 vector plasmid-transfected human umbilical vein endothelial cells (HUVECs) resembling EndoMT were monitored by qPCR, immunocytochemistry and western blots. Subsequently, in mice, a Cre-LoxP strategy for inactivation of Hey2 specifically in the endothelium was used to study the biological consequences. Total body irradiation and radiation proctitis were monitored to investigate the impact of conditional Hey2 deletion on intestinal stem cells and microvascular compartment radiosensitivity, EndoMT and rectal damage severity. We found that EndoMT occurs in irradiated HUVECs with concomitant Hey2 mRNA and protein increase. While Hey2 silencing has no effect on radiation-induced EndoMT in vitro, Hey2 overexpression is sufficient to induce phenotypic conversion of endothelial cells. In mice, the conditional deletion of Hey2 reduces EndoMT frequency and the severity of rectal tissue damage. Our data indicate that the reduction in mucosal damage occurs through decline in stem/clonogenic epithelial cell loss mediated by microvascular protection. EndoMT is involved in radiation proctitis and this study demonstrates that a strategy based on the reduction of EndoMT mitigates intestinal tissue damage.

Synergistic effect of human Bone Morphogenic Protein-2 and Mesenchymal Stromal Cells on chronic wounds through hypoxia-inducible factor-1 α induction

Chronic skin ulcers and burns require advanced treatments. Mesenchymal Stromal Cells (MSCs) are effective in treating these pathologies. Bone Morphogenic Protein-2 (BMP-2) is known to enhance angiogenesis. We investigated whether recombinant human hBMP-2 potentiates the effect of MSCs on wound healing. Severe ulceration was induced in rats by irradiation and treated by co-infusion of MSCs with hBMP-2 into the ulcerated area which accelerated wound healing. Potentiation of the effect of MSCs by hBMP-2 on endothelial repair improved skin healing. HBMP-2 and MSCs synergistically, in a supra additive or enhanced manner, renewed tissue structures, resulting in normalization of the epidermis, hair follicles, sebaceous glands, collagen fibre density, and blood vessels. Co-localization of MSCs with CD31 + cells suggests recruitment of endothelial cells at the site of injection. HBMP-2 and MSCs enhanced angiogenesis and induced micro-vessel formation in the dermis where hair follicles were regenerated. HBMP-2 acts by causing hypoxia-inducible factor-1 α (HIF-1α) expression which impacts endothelial tube formation and skin repair. This effect is abolished by siRNA. These results propose that new strategies adding cytokines to MSCs should be evaluated for treating radiation-induced dermatitis, burns, and chronic ulcers in humans.

Mesenchymal Stem Cell Therapy Protects Lungs from Radiation-Induced Endothelial Cell Loss by Restoring Superoxide Dismutase 1 Expression

AIMS

Radiation-induced normal tissue toxicity is closely linked to endothelial cell (EC) damage and dysfunction (acute effects). However, the underlying mechanisms of radiation-induced adverse late effects with respect to the vascular compartment remain elusive, and no causative radioprotective treatment is available to date.

RESULTS

The importance of injury to EC for radiation-induced late toxicity in lungs after whole thorax irradiation (WTI) was investigated using a mouse model of radiation-induced pneumopathy. We show that WTI induces EC loss as long-term complication, which is accompanied by the development of fibrosis. Adoptive transfer of mesenchymal stem cells (MSCs) either derived from bone marrow or aorta (vascular wall-resident MSCs) in the early phase after irradiation limited the radiation-induced EC loss and fibrosis progression. Furthermore, MSC-derived culture supernatants rescued the radiation-induced reduction in viability and long-term survival of cultured lung EC. We further identified the antioxidant enzyme superoxide dismutase 1 (SOD1) as a MSC-secreted factor. Importantly, MSC treatment restored the radiation-induced reduction of SOD1 levels after WTI. A similar protective effect was achieved by using the SOD-mimetic EUK134, suggesting that MSC-derived SOD1 is involved in the protective action of MSC, presumably through paracrine signaling.

INNOVATION

In this study, we explored the therapeutic potential of MSC therapy to prevent radiation-induced EC loss (late effect) and identified the protective mechanisms of MSC action.

CONCLUSIONS

Adoptive transfer of MSCs early after irradiation counteracts radiation-induced vascular damage and EC loss as late adverse effects. The high activity of vascular wall-derived MSCs for radioprotection may be due to their tissue-specific action. Antioxid. Redox Signal. 26, 563-582.

Hemodynamic Flow-Induced Mechanotransduction Signaling Influences the Radiation Response of the Vascular Endothelium

Hemodynamic shear stress is defined as the physical force exerted by the continuous flow of blood in the vascular system. Endothelial cells, which line the inner layer of blood vessels, sense this physiological force through mechanotransduction signaling and adapt to maintain structural and functional homeostasis. Hemodynamic flow, shear stress and mechanotransduction signaling are, therefore, an integral part of endothelial pathophysiology. Although this is a well-established concept in the cardiovascular field, it is largely dismissed in studies aimed at understanding radiation injury to the endothelium and subsequent cardiovascular complications. We and others have reported on the differential response of the endothelium when the cells are under hemodynamic flow shear compared with static culture. Further, we have demonstrated significant differences in the gene expression of static versus shear-stressed irradiated cells in four key pathways, reinforcing the importance of shear stress in understanding radiation injury of the endothelium. This article further emphasizes the influence of hemodynamic shear stress and the associated mechanotransduction signaling on physiological functioning of the vascular endothelium and underscores its significance in understanding radiation injury to the vasculature and associated cardiac complications. Studies of radiation effect on endothelial biology and its implication on cardiotoxicity and vascular complications thus far have failed to highlight the significance of these factors. Factoring in these integral parts of the endothelium will enhance our understanding of the contribution of the endothelium to radiation biology. Without such information, the current approaches to studying radiation-induced injury to the endothelium and its consequences in health and disease are limited.

Identification of Endothelial-to-Mesenchymal Transition as a Potential Participant in Radiation Proctitis

The endothelial-to-mesenchymal transition (EndoMT) is a crucial cellular process during heart development necessary to the formation of cardiac valves. This embryonic process reappears in several pathological situations, such as vascular injury or organ fibrosis of various etiologies, as a mediator of extracellular matrix-producing cells. Because radiation induces both vascular damage and fibrosis, we investigated whether radiation exposure induces EndoMT in primary human intestinal microvascular endothelial cells (HIMECs) and whether EndoMT contributes to radiation-induced rectal damage in humans and in a preclinical model of radiation proctitis in mice. Irradiated HIMECs show phenotypic hallmarks of radiation-induced endothelial cell activation in vitro. Moreover, HIMECs undergo changes in molecular expression pattern compatible with EndoMT, with up-regulation of mesenchymal markers and down-regulation of endothelial markers via transforming growth factor/Smad pathway activation. In vivo, EndoMT readily occurs in the human rectum after radiation therapy for rectal adenocarcinoma. Finally, EndoMT was observed in rectal mucosal and submucosal microvessels in a preclinical model of radiation proctitis in Tie2-green fluorescent protein reporter-expressing mice all along radiation proctitis development, also associated with transforming growth factor/Smad pathway activation. In conclusion, radiation-induced cell activation and tissue inflammation constitute a setting that fosters the phenotypic conversion of endothelial cells into mesenchymal cells. Therefore, EndoMT is identified as a potential participant in radiation-induced gut damage and may represent an interesting therapeutic target in cases of radiation-induced pelvic disease.

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.

Chronic Gamma-Irradiation Induces a Dose-Rate-Dependent Pro-inflammatory Response and Associated Loss of Function in Human Umbilical Vein Endothelial Cells

A central question in radiation protection research is dose and dose-rate relationship for radiation-induced cardiovascular diseases. The response of endothelial cells to different low dose rates may contribute to help estimate risks for cardiovascular diseases by providing mechanistic understanding. In this study we investigated whether chronic low-dose-rate radiation exposure had an effect on the inflammatory response of endothelial cells and their function. Human umbilical vein endothelial cells (HUVECs) were chronically exposed to radiation at a dose of 1.4 mGy/h or 4.1 mGy/h for 1, 3, 6 or 10 weeks. We determined the pro-inflammatory profile of HUVECs before and during radiation exposure, and investigated the functional consequences of this radiation exposure by measuring their capacity to form vascular networks in matrigel. Expression levels of adhesion molecules such as E-selectin, ICAM-1 and VCAM-1, and the release of pro-inflammatory cytokines such as MCP-1, IL-6 and TNF-α were analyzed. When a total dose of 2 Gy was given at a rate of 4.1 mGy/h, we observed an increase in IL-6 and MCP-1 release into the cell culture media, but this was not observed at 1.4 mGy/h. The increase in the inflammatory profile induced at the dose rate of 4.1 mGy/h was also correlated with a decrease in the capacity of the HUVECs to form a vascular network in matrigel. Our results suggest that dose rate is an important parameter in the alteration of HUVEC inflammatory profile and function.

Mechanisms of cardiac radiation injury and potential preventive approaches

In addition to cytostatic treatment and surgery, the most common cancer treatment is gamma radiation. Despite sophisticated radiological techniques however, in addition to irradiation of the tumor, irradiation of the surrounding healthy tissue also takes place, which results in various side-effects, depending on the absorbed dose of radiation. Radiation either damages the cell DNA directly, or indirectly via the formation of oxygen radicals that in addition to the DNA damage, react with all cell organelles and interfere with their molecular mechanisms. The main features of radiation injury besides DNA damage is inflammation and increased expression of pro-inflammatory genes and cytokines. Endothelial damage and dysfunction of capillaries and small blood vessels plays a particularly important role in radiation injury. This review is focused on summarizing the currently available data concerning the mechanisms of radiation injury, as well as the effectiveness of various antioxidants, anti-inflammatory cytokines, and cytoprotective substances that may be utilized in preventing, mitigating, or treating the toxic effects of ionizing radiation on the heart.

Protective effects of nutritional supplementation with arginine and glutamine on the penis of rats submitted to pelvic radiation

Radiotherapy is widely used to treat pelvic malignancies, but normal tissues near the target tumour are often affected. Our aims were thus to determine whether the structural organization of the rat penis is altered by radiation, and whether supplementation with L-arginine (ARG) or L-glutamine (GLN) would have protective effects against these alterations. Groups of rats were treated with: no intervention (CONTR); pelvic radiation, followed by sacrifice 7 (RAD7) or 15 (RAD15) days later; and pelvic radiation, daily supplementation with ARG or GLN, followed by sacrifice 7 (RAD7+ARG, RAD7+GLN) or 15 (RAD15+ARG, RAD15+GLN) days after radiation. Structural components in the corpus cavernosum (CC), tunica albuginea of the corpus spongiosum (TACS) and urethral epithelium (UE) were analysed using stereological and immunohistochemical methods. The results showed that in the CC, connective tissue was increased by 18% in RAD15 (p < 0.04), but this change was partially prevented in RAD15+GLN (p < 0.05) and RAD15+ARG (p < 0.04). The fibrous matrix of the CC trabeculae stained evenly for collagen type I. In RAD15, the intensity of the labelling was increased, whereas in RAD15+GLN and RAD15+ARG the staining was similar to that of CONTR. No staining changes were seen in the groups that were sacrificed 7 days after radiation. Cavernosal elastic fibre content in RAD15 was increased by 61% (p < 0.004), and this was prevented in RAD15+ARG (p < 0.004) but not in RAD15+GLN. In TACS, the amino acids protected (p < 0.02) against the radiation-induced 92% increase in elastic fibre content, but only in RAD15. Cell density in the UE, as well as UE thickness, were reduced by 30% in RAD15 (p < 0.004), and there were protective effects of both amino acids. In conclusion, radiation-induced alterations in penile structures tend to be more pronounced 15 days after radiation session. Both ARG and GLN have protective effects against these changes, with the former being slightly more effective.

Membrane signaling induced by high doses of ionizing radiation in the endothelial compartment. Relevance in radiation toxicity

Tumor areas can now be very precisely delimited thanks to technical progress in imaging and ballistics. This has also led to the development of novel radiotherapy protocols, delivering higher doses of ionizing radiation directly to cancer cells. Despite this, radiation toxicity in healthy tissue remains a major issue, particularly with dose-escalation in these new protocols. Acute and late tissue damage following irradiation have both been linked to the endothelium irrigating normal tissues. The molecular mechanisms involved in the endothelial response to high doses of radiation are associated with signaling from the plasma membrane, mainly via the acid sphingomyelinase/ceramide pathway. This review describes this signaling pathway and discusses the relevance of targeting endothelial signaling to protect healthy tissues from the deleterious effects of high doses of radiation.

Serum Proteome Analysis for Profiling Predictive Protein Markers Associated with the Severity of Skin Lesions Induced by Ionizing Radiation

The finding of new diagnostic and prognostic markers of local radiation injury, and particularly of the cutaneous radiation syndrome, is crucial for its medical management, in the case of both accidental exposure and radiotherapy side effects. Especially, a fast high-throughput method is still needed for triage of people accidentally exposed to ionizing radiation. In this study, we investigated the impact of localized irradiation of the skin on the early alteration of the serum proteome of mice in an effort to discover markers associated with the exposure and severity of impending damage. Using two different large-scale quantitative proteomic approaches, 2D-DIGE-MS and SELDI-TOF-MS, we performed global analyses of serum proteins collected in the clinical latency phase (days 3 and 7) from non-irradiated and locally irradiated mice exposed to high doses of 20, 40 and 80 Gy which will develop respectively erythema, moist desquamation and necrosis. Unsupervised and supervised multivariate statistical analyses (principal component analysis, partial-least square discriminant analysis and Random Forest analysis) using 2D-DIGE quantitative protein data allowed us to discriminate early between non-irradiated and irradiated animals, and between uninjured/slightly injured animals and animals that will develop severe lesions. On the other hand, despite a high number of animal replicates, PLS-DA and Random Forest analyses of SELDI-TOF-MS data failed to reveal sets of MS peaks able to discriminate between the different groups of animals. Our results show that, unlike SELDI-TOF-MS, the 2D-DIGE approach remains a powerful and promising method for the discovery of sets of proteins that could be used for the development of clinical tests for triage and the prognosis of the severity of radiation-induced skin lesions. We propose a list of 15 proteins which constitutes a set of candidate proteins for triage and prognosis of skin lesion outcomes.

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.

Gastrointestinal radiation injury: Symptoms, risk factors and mechanisms

Ionising radiation therapy is a common treatment modality for different types of cancer and its use is expected to increase with advances in screening and early detection of cancer. Radiation injury to the gastrointestinal tract is important factor working against better utility of this important therapeutic modality. Cancer survivors can suffer a wide variety of acute and chronic symptoms following radiotherapy, which significantly reduces their quality of life as well as adding an extra burden to the cost of health care. The accurate diagnosis and treatment of intestinal radiation injury often represents a clinical challenge to practicing physicians in both gastroenterology and oncology. Despite the growing recognition of the problem and some advances in understanding the cellular and molecular mechanisms of radiation injury, relatively little is known about the pathophysiology of gastrointestinal radiation injury or any possible susceptibility factors that could aggravate its severity. The aims of this review are to examine the various clinical manifestations of post-radiation gastrointestinal symptoms, to discuss possible patient and treatment factors implicated in normal gastrointestinal tissue radiosensitivity and to outline different mechanisms of intestinal tissue injury.

Nutritional supplementation with L-arginine prevents pelvic radiation-induced changes in morphology, density, and regulating factors of blood vessels in the wall of rat bladder

PURPOSE

To determine whether L-arginine has protective effects against radiation-induced alterations in the morphology and regulatory factors of vesical blood vessels in rats.

METHODS

Male rats aged 3-4 months were divided into groups of 10 animals each: (a) controls, consisting of non-treated animals; (b) radiated-only rats; and (c) radiated rats receiving L-arginine supplementation. Radiation was in one session of 10 Gy and was aimed at the pelvic-abdominal region. L-arginine was administered once a day (0.65 g/kg body weight), starting 7 days before radiation and continuing until killing on the 16th day after radiation. The density, relative area, and wall thickness of blood vessels were measured in the vesical lamina propria using histological methods, and the expression of vascular endothelial growth factor (VEGF) and fibroblast growth factors (FGF) in the bladder wall was assessed by RT-PCR.

RESULTS

Compared with controls, radiation alone decreased the density and relative area of blood vessels by 32 % (p < 0.01) and 25 % (p < 0.05), respectively, and reduced the arterial wall thickness by 42 % (p < 0.004). VEGF and FGF mRNA levels after radiation were diminished by 67 % (p < 0.002) and 56 % (p < 0.04), respectively. The radiated animals supplemented with L-arginine were not significantly different from controls.

CONCLUSIONS

Pelvic radiation leads to significant vesical modifications, as in the morphology of blood vessels and in VEGF and FGF expression. All these changes, however, were prevented by L-arginine treatment. These results emphasize, therefore, the potential use of this amino acid as a radioprotective drug.

Long-term alterations of cytokines and growth factors expression in irradiated tissues and relation with histological severity scoring

Purpose

Beside its efficacy in cancer treatment, radiotherapy induces degeneration of healthy tissues within the irradiated area. The aim of this study was to analyze the variations of proinflammatory (IL-1α, IL-2, IL-6, TNF-α, IFN-γ), profibrotic (TGF-β1), proangiogneic (VEGF) and stem cell mobilizing (GM-CSF) cytokines and growth factors in an animal model of radiation-induced tissue degeneration.

Materials and Methods

24 rats were irradiated unilaterally on the hindlimb at a monodose of 30 Gy. Six weeks (n = 8), 6 months (n = 8) and 1 year (n = 8) after irradiation the mediators expression in skin and muscle were analyzed using Western blot and the Bio-Plex® protein array (BPA) technology. Additional histological severity for fibrosis, inflammation, vascularity and cellularity alterations scoring was defined from histology and immnunohistochemistry analyses.

Results

A significant increase of histological severity scoring was found in irradiated tissue. Skin tissues were more radio-sensitive than muscle. A high level of TGF-β1 expression was found throughout the study and a significant relation was evidenced between TGF-β1 expression and fibrosis scoring. Irradiated tissue showed a chronic inflammation (IL-2 and TNF-α significantly increased). Moreover a persistent expression of GM-CSF and VEGF was found in all irradiated tissues. The vascular score was related to TGF-β1 expression and the cellular alterations score was significantly related with the level of IL-2, VEGF and GM-CSF.

Conclusion

The results achieved in the present study underline the complexity and multiplicity of radio-induced alterations of cytokine network. It offers many perspectives of development, for the comprehension of the mechanisms of late injuries or for the histological and molecular evaluation of the mode of action and the efficacy of rehabilitation techniques.

[Radiotherapy and atherosclerosis: current data and issues]

The continuous optimization of cancer treatment with radiotherapy raises the problem of long-term issue of patients treated and cured by ionizing radiation, with the possible occurrence of second cancers or nonmalignant complications. Among these, cardiovascular diseases are prevalent and may affect up to 40 % of patients depending on the location of the irradiation. Recent epidemiological studies show that this problem is underestimated and with no real prospective studies. The management of these patients with vascular risk, or with very high vascular risk for those with pre-existing traditional cardiovascular risk factors, remains to be determined. The pathophysiological mechanisms of radiation-induced atherosclerosis have not yet been clarified. Many efforts are still needed to identify patients at risk and to find or to propose an appropriate treatment. Prolonged vascular follow-up of patients after their radiotherapy should now be integrated into patterns of care, especially because the setting up of sophisticated technical platforms of radiotherapy do not necessarily solve the issue of cardiovascular risk after treatment. double dagger.

Novel synthetic SOD/catalase mimetics can mitigate capillary endothelial cell apoptosis caused by ionizing radiation

Numerous in vitro and in vivo studies have shown that the endothelial cells of the microvasculature of the lung and kidney are damaged by exposure to ionizing radiation, and this sustained endothelial cell injury is involved in the early and late radiation effects observed in these tissues. It is well accepted that ionizing radiation causes the generation of reactive oxygen species during exposure that results in damage to DNA and cellular organelles. It is more controversial, however, whether additional biochemical events or long-lived radicals occur and persist postirradiation that amplify and initiate new forms of cellular damage. Two families of Eukarion (EUK) compounds have been synthesized that possess superoxide dismutase (SOD), catalase and peroxidase activities. The Mn porphyrins are available orally whereas the salen Mn complexes are administered by injection. In the present study we have examined the ability of these SOD/catalase mimetics to prevent apoptosis of endothelial cells when administered 1 h postirradiation (mitigation). A range of salen Mn complex (EUK-189 and EUK-207) and Mn porphyrins (EUK-418, -423, -425, -450, -451, -452, -453) were used to treat endothelial cells 1 h after the cells received 2-20 Gy ionizing radiation in vitro. Two lead compounds, EUK-207 at a dose of 30 microM and EUK-451 at a dose of 10 microM, exhibited low toxicity and mitigated radiation-induced apoptosis. Future animal studies will test whether these compounds protect when administered after radiation exposure as would be done after a radiological accident or a terrorism event.

Intensity-modulated radiotherapy for a rendu-osler-weber disease patient with recurrent severe epistaxis: a case report

We present a case of a Rendu-Osler-Weber disease patient with recurrent life threatening epistaxis demanding multiple blood transfusions despite of repetitive endoscopic laser and electrocoagulations, endovascular embolisation, septodermoplasty, and long-term intranasal dressings. As alternative treatment modalities repeatedly failed and the patient became almost permanently dependent on nasal dressing, we performed a highly conformal intensity-modulated radiotherapy of the nasal cavity; a total dose of 50 Gy in 2 Gy single fractions was applied. The therapy was very well tolerated, no acute toxicities occurred. Two weeks after the last radiation dose had been applied, the nasal dressing could be removed without problems. Endoscopical control revealed an almost avascular white mucosa without any trace of bleeding spots; previously existing hemangiomas and crusts had disappeared. After a 1-year-follow up, the patient had no significant recurrent epistaxis.