Interleukin 1beta (IL1B) signaling is a critical component of radiation-induced skin fibrosis

Portrait of inflammatory response to ionizing radiation treatment

Ionizing radiation (IR) activates both pro-and anti-proliferative signal pathways producing an imbalance in cell fate decision. IR is able to regulate several genes and factors involved in cell-cycle progression, survival and/or cell death, DNA repair and inflammation modulating an intracellular radiation-dependent response. Radiation therapy can modulate anti-tumour immune responses, modifying tumour and its microenvironment. In this review, we report how IR could stimulate inflammatory factors to affect cell fate via multiple pathways, describing their roles on gene expression regulation, fibrosis and invasive processes. Understanding the complex relationship between IR, inflammation and immune responses in cancer, opens up new avenues for radiation research and therapy in order to optimize and personalize radiation therapy treatment for each patient.

Endothelial perturbations and therapeutic strategies in normal tissue radiation damage

Most cancer patients are treated with radiotherapy, but the treatment can also damage the surrounding normal tissue. Radiotherapy side-effects diminish patients’ quality of life, yet effective biological interventions for normal tissue damage are lacking. Protecting microvascular endothelial cells from the effects of irradiation is emerging as a targeted damage-reduction strategy. We illustrate the concept of the microvasculature as a mediator of overall normal tissue radiation toxicity through cell death, vascular inflammation (hemodynamic and molecular changes) and a change in functional capacity. Endothelial cell targeted therapies that protect against such endothelial cell perturbations and the development of acute normal tissue damage are mostly under preclinical development. Since acute radiation toxicity is a common clinical problem in cutaneous, gastrointestinal and mucosal tissues, we also focus on damage in these tissues.

Identification of several hub-genes associated with periodontitis using integrated microarray analysis

The aim of the present study was to identify differentially expressed genes and biological processes associated with periodontitis. In this study, the most significant 200 differentially expressed genes associated with periodontitis were identified using integrated analysis of multiple microarray data in combination with screening for genome-wide relative significance and genome-wide global significance. Gene Ontology (GO) enrichment analysis and pathway analysis were performed using the GO website and Kyoto Encyclopedia of Genes and Genomes (KEGG). A protein-protein interaction (PPI) network was constructed based on the Search Tool for the Retrieval of Interacting Genes/Proteins. The top 200 differentially expressed genes were found to be highly associated with periodontitis. GO enrichment analyses revealed that the identified genes were significantly enriched in terms of response to organic substance, response to wounding and cell migration. The most common term of the KEGG pathway was cytokine-cytokine receptor interaction. PPI network analysis indicated that interleukin (IL)8, IL1β, vascular endothelial growth factor A, intercellular adhesion molecule 1, PTGS2 and CXCL10 were hub genes, which formed numerous interactions with several genes. In conclusion, the present study identified numerous genes that were differentially expressed in periodontitis, as well as determined the biological pathways and PPI network associated with those genes.

Combined drug and surgery treatment of plutonium-contaminated wounds: indications obtained using a rodent model

There is an important requirement following accidental actinide contamination of wounds to limit the dissemination and retention of such alpha-emitting radionuclides. To reduce wound and systemic contamination, treatment approaches include chelation therapy with or without wound excision. However, it has been hypothesized that wound excision could lead to increased contaminant release and systemic organ retention. This study in the rat addresses this question. Anesthetized rats were contaminated with plutonium nitrate following wounding by deep incision of hind leg muscle. Excision of tissue at the contaminated site was performed 7 d later with or without Diethylene Triamine Pentaacetic Acid (DTPA) treatment (30 μmol kg⁻¹ i.v.). Pu urinary excretion was then measured for a further 3 d, and animals were euthanized at 14 d after contamination. Tissue samples were evaluated for Pu activity and histology. At 7 d after contamination, around 50% of the initial activity remained at the wound site. An average of 16% of this activity was then removed by surgery. Surgery alone resulted in increased urinary excretion, suggesting release from the wound site, but no subsequent increases in organ retention (bone, liver) were observed at 14 d. Indeed, organ Pu activity was slightly reduced. The combination of surgery and DTPA or DTPA treatment alone was much more effective than excision alone as shown by the markedly increased urinary Pu excretion and decreased tissue levels. This is the first report in an experimental rodent model of resection of Pu-contaminated wound. Urinary excretion data provide evidence for the release of activity as a result of surgery, but this does not appear to lead to further Pu organ retention. However, a combination of prior DTPA treatment with wound excision is particularly effective.

Role of interleukin-1β in radiation-enhancement of MDA-MB-231 breast cancer cell invasion

The ability of radiation to increase the invasiveness of cancer cells is associated with the inflammatory response, which is induced in almost all irradiated patients. For breast cancer patients, elevated plasma levels of the inflammatory cytokine interleukin-1β (IL1β) persisted for a few weeks after completion of radiotherapy. The aim of this study was to determine whether IL1β is involved in the enhancement of breast cancer cell invasion induced by radiation. The role of IL1β was assessed with invasion chambers where irradiated fibroblasts were used as chemoattractant for the MDA-MB-231 breast cancer cells plated in the upper compartment. The ability of IL1β to stimulate the expression of cyclooxygenase-2 (COX-2) and biosynthesis of the prostaglandin E2 (PGE2) in MDA-MB-231 cells were also determined. Our results show that radiation-enhancement of MDA-MB-231 cell invasion was prevented with an anti-IL1β antibody. The production of IL1β was increased in irradiated fibroblasts, while the invasiveness of the MDA-MB-231 cells not exposed to irradiated fibroblasts was favored by adding this cytokine. Furthermore, addition of the COX-2 inhibitor NS-398 prevented the stimulation of cancer cell invasion induced either by irradiated fibroblasts or IL1β. We propose that the effect of IL1β on the invasiveness of the MDA-MB-231 cells involves elevation of matrix metalloproteinase-9 (MMP-9) production, induction of COX-2 expression and PGE2 biosynthesis. In conclusion, this study supports the involvement of IL1β in the radiation-enhancement of breast cancer cell invasion.

Protective effect of a Butea monosperma (Lam.) Taub. flowers extract against skin inflammation: antioxidant, anti-inflammatory and matrix metalloproteinases inhibitory activities

ETHNOPHARMACOLOGICAL RELEVANCE

Butea monosperma (Lam.) Taubert (Syn. Butea frondosa; family Fabaceae) is a common plant of the Indian continent (Das et al., 2011; Sharma and Deshwal, 2011). The brightly orange flowers of this plant are widely used in traditional medicine and more particularly for inflammatory disease.

AIM OF THE STUDY

In vitro anti-inflammatory mechanism of a hydroethanolic extract of B. monosperma flowers (BME) and more specifically of an enriched fraction in butrin and isobutrin (BI) was studied using cell culture of Normal Human Keratinocyte, cells involved in the skin inflammatory.

MATERIALS AND METHODS

Dried and crushed B. monosperma flowers were extracted with Ethanol/H2O (70/30 v/v). The butrin/isobutrin fraction was obtained by centrifugal Partition Chromatography (CPC). Experiments were conducted on UV-B treated normal human epidermis keratinocytes, cells involved in the skin inflammatory response. To evaluate extract anti-inflammatory activity, cytokines IL-1β, IL-6, IL-8, prostaglandin E2 and metalloproteinases MMP-1, -2, -9 and -10 were measured in the cells supernatant.

RESULTS

Our data clearly showed that hydroalcoholic B. monosperma flower extract was able to decrease the secretion of IL-1β, IL-6 and IL-8 pro-inflammatory cytokines of -32, -33 and -18% respectively. Interestingly, Prostaglandin E2 production and the secretion of MMP-1, -2, -9 and -10 were also inhibited. Same results were observed in presence of enriched fraction in butrin and isobutrin and confirmed the participation of these molecules in the anti-inflammatory activity.

CONCLUSION

These results explain the anti-inflammatory activity of B. monosperma and confirm the interest to use it in traditional Indian medicine. Moreover, its metalloproteinases inhibitory activities coupled with its anti-inflammatory action also give anti-aging property to this plant.

Reduced side effects by proton microchannel radiotherapy: study in a human skin model

The application of a microchannel proton irradiation was compared to homogeneous irradiation in a three-dimensional human skin model. The goal is to minimize the risk of normal tissue damage by microchannel irradiation, while preserving local tumor control through a homogeneous irradiation of the tumor that is achieved because of beam widening with increasing track length. 20 MeV protons were administered to the skin models in 10- or 50-μm-wide irradiation channels on a quadratic raster with distances of 500 μm between each channel (center to center) applying an average dose of 2 Gy. For comparison, other samples were irradiated homogeneously at the same average dose. Normal tissue viability was significantly enhanced after microchannel proton irradiation compared to homogeneous irradiation. Levels of inflammatory parameters, such as Interleukin-6, TGF-Beta, and Pro-MMP1, were significantly lower in the supernatant of the human skin tissue after microchannel irradiation than after homogeneous irradiation. The genetic damage as determined by the measurement of micronuclei in keratinocytes also differed significantly. This difference was quantified via dose modification factors (DMF) describing the effect of each irradiation mode relative to homogeneous X-ray irradiation, so that the DMF of 1.21 ± 0.20 after homogeneous proton irradiation was reduced to 0.23 ± 0.11 and 0.40 ± 0.12 after microchannel irradiation using 10- and 50-μm-wide channels, respectively. Our data indicate that proton microchannel irradiation maintains cell viability while significantly reducing inflammatory responses and genetic damage compared to homogeneous irradiation, and thus might improve protection of normal tissue after irradiation.

IL-1 generated subsequent to radiation-induced tissue injury contributes to the pathogenesis of radiodermatitis

Radiation injury in the skin causes radiodermatitis, a condition in which the skin becomes inflamed and the epidermis can break down. This condition causes significant morbidity and if severe it can be an independent factor that contributes to radiation mortality. Radiodermatitis is seen in some settings of radiotherapy for cancer and is also of concern as a complication post-radiation exposure from accidents or weapons, such as a "dirty bomb". The pathogenesis of this condition is incompletely understood. Here we have developed a murine model of radiodermatitis wherein the skin is selectively injured by irradiation with high-energy electrons. Using this model we showed that the interleukin-1 (IL-1) pathway plays a significant role in the development of radiodermatitis. Mice that lack either IL-1 or the IL-1 receptor developed less inflammation and less severe pathological changes in their skin, especially at later time-points. These findings suggest that IL-1 pathway may be a potential therapeutic target for reducing the severity of radiodermatitis.

Response patterns of cytokines/chemokines in two murine strains after irradiation

PURPOSE

To determine the plasma concentrations of acute responding cytokines/chemokines following 9-Gy ionizing radiation in C57BL/6 (radiation tolerant) and C3H/HeN (radiation sensitive) murine strains.

METHODS AND MATERIALS

Mice (5/group) received 9-Gy total body irradiation (TBI), and the plasma from each mouse was collected at 6h or 1, 2, 4, or 10 days after TBI. A multiplex bead array was used to assess the levels of 32 cytokines/chemokines in plasma to determine their common and strain-specific temporal responses.

RESULTS

The plasma levels of five cytokines/chemokines (Axl, FasL, ICAM-1, TARC, and TSLP) were beyond the detectable level. Five (VEGF, IL-2, IL-5, IL-17, and CD30) were unaffected by irradiation in either strain. Temporal patterns were similar in both murine strains for 10 of the cytokines tested, including G-CSF, IL-6, TCA-3, MCP-1, MIP-1γ, KC, CXCL 13, CXCL 16, MDC, and TIMP-1; the other 12 molecules (GM-CSF, IL-3, SCF, IL-1β, IL-4, IL-10, IL-12p70, MIP-1α, Eotaxin, TNF-α, sTNF-R1, and CD40) showed strain-specific response patterns. While a number of cytokines had temporal response patterns following TBI, the strains exhibited quantitatively different results.

CONCLUSIONS

The levels of 27 of the 32 plasma cytokines measured indicate the following: (1) different cytokine concentrations and temporal patterns in the two strains may partly explain different radiation sensitivities and sequelae following irradiation; (2) many of the cytokines/chemokines exhibit similar temporal responses in the two strains. These responses suggest the potential value of using a panel of cytokine/chemokine temporal patterns for radiation dosimetry. Although radiation doses will be difficult to quantitate due to the large variation in levels and temporal responses exhibited in the two murine strains, serial measurements of cytokines might help identify subjects exposed to radiation.

Radiation-induced damage in different segments of the rat intestine after external beam irradiation of the liver

INTRODUCTION

The out-of-field effects on the intestine, caused by radiation treatment of a parenchymatous organ, have not previously been studied.

METHODS

A single dose of 25Gy was administered percutaneously to the liver of male Wistar rats after a planning CT-scan. Sham-irradiated animals served as controls. At 1, 6, 24, 96h, 1.5 and 3months the duodenum, jejunum, ileum and distal colon were removed, washed and deep-frozen or prepared for paraffin staining.

RESULTS

All animals survived the treatment. Epithelial cell damage occurred in all small-intestinal segments. However, prolonged denudation of the villi together with destruction of the crypt lining was only observed in the ileum, resulting in deficient regeneration. In the colon, changes were minor. Radiation mucositis with granulocyte (MP0+) infiltration was seen from 1 to 24h in the duodenum and jejunum, when ED1+ macrophages, CD3+ T-lymphocytes, and CD34+ hematopoietic precursor cells were recruited, accompanied by an increase in the chemokines MCP-1, MIP-1α, MIP3α and Il-8. In the ileum, early granulocyte infiltration was delayed but continuous. Recruitment of macrophages and lymphocytes was deficient and induction of chemokines as of the adhesion molecules PECAM-1, ICAM-1 was lacking.

CONCLUSION

Post-irradiation damage to the ileum was delayed and followed by an altered repair process with structural changes of the villi. The observed changes might result from a higher sensitivity to oxidative stress mechanisms with subsequent damage of the regenerative capacity of the crypt-villus axis, accompanied by a sustained "inflammatory response" and vascular damage with a lack of regeneratory cell recruitment.

Development of a combined radiation and burn injury model

Combined radiation and burn injuries are likely to occur after nuclear events, such as a meltdown accident at a nuclear energy plant or a nuclear attack. Little is known about the mechanisms by which combined injuries result in higher mortality than by either insult alone, and few animal models exist for combined radiation and burn injury. Herein, the authors developed a murine model of radiation and scald burn injury. Mice were given a single dose of 0, 2, 4, 5, 6, or 9 Gray (Gy) alone, followed by a 15% TBSA scald burn. All mice receiving ≤4 Gy of radiation with burn survived combined injury. Higher doses of radiation (5, 6, and 9 Gy) followed by scald injury had a dose-dependent increase in mortality (34, 67, and 100%, respectively). Five Gy was determined to be the ideal dose to use in conjunction with burn injury for this model. There was a decrease in circulating white blood cells in burn, irradiated, and combined injury (5 Gy and burn) mice by 48 hours postinjury compared with sham (49.7, 11.6, and 57.3%, respectively). Circulating interleukin-6 and tumor necrosis factor-α were increased in combined injury at 48 hours postinjury compared with all other treatment groups. Prolonged overproduction of proinflammatory cytokines could contribute to subsequent organ damage. Decreased leukocytes might exacerbate immune impairment and susceptibility to infections. Future studies will determine whether there are long lasting consequences of this early proinflammatory response and extended decrease in leukocytes.

Protective role of Vernonia cinerea L. against gamma radiation—induced immunosupression and oxidative stress in mice

The radioprotective effect of Vernonia cinerea extract was studied in balb/c mice. Whole-body irradiation of γ-rays (6 Gy) given to animals reduced the white blood cell count, bone marrow cellularity and α-esterase positive cells in control animals, which were elevated by the administration of V. cinerea extract (20 mg/kg body weight [b.wt.], intraperitoneally [i.p.]). The elevated levels of serum enzymes alkaline phosphatase (ALP), glutamate pyruvate transferases (GPT) and lipid peroxidation (LPO) after irradiation were also reduced with V. cineria extract administration. V. cinerea treatment also significantly enhanced the animal’s antioxidant status by enhancing the activities superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx) and reduced glutathione (GSH) level in irradiated animals. Histopathological analysis of liver and small intestine also suggests that V. cinerea could reduce the tissue damages induced by radiation. The level of pro-inflammatory cytokines such as interleukin 1β (IL-1β), tumour necrosis factor α (TNF-α) and C-reactive protein (CRP) elevated after irradiation, which were significantly reduced by V. cinerea extract administration. On the other hand, the extract stimulated the production of other cytokines such as granulocyte monocyte—colony stimulating factor (GM-CSF) and interferon-γ (IFN-γ) in animals exposed to radiation. Agarose gel electrophoresis of DNA isolated from bone marrow of control animals showed heavy DNA damage, but a reduced DNA damage was seen in animals treated with V. cinerea extract. Administration of V. cinerea did not compromise the anti-neoplastic efficiency of radiation. In fact, there was a synergistic action of radiation and V. cinerea in reducing the solid tumours in mice. Methanolic extract of V. cinerea given i.p. showed a significant radioprotective activity without compromising the radiotherapeutic efficacy of radiation, indicating its possible use as an adjuvant during radiotherapy.

Gene signatures in wound tissue as evidenced by molecular profiling in the chick embryo model

BACKGROUND

Modern functional genomic approaches may help to better understand the molecular events involved in tissue morphogenesis and to identify molecular signatures and pathways. We have recently applied transcriptomic profiling to evidence molecular signatures in the development of the normal chicken chorioallantoic membrane (CAM) and in tumor engrafted on the CAM. We have now extended our studies by performing a transcriptome analysis in the "wound model" of the chicken CAM, which is another relevant model of tissue morphogenesis.

RESULTS

To induce granulation tissue (GT) formation, we performed wounding of the chicken CAM and compared gene expression to normal CAM at the same stage of development. Matched control samples from the same individual were used. We observed a total of 282 genes up-regulated and 44 genes down-regulated assuming a false-discovery rate at 5% and a fold change > 2. Furthermore, bioinformatics analysis lead to the identification of several categories that are associated to organismal injury, tissue morphology, cellular movement, inflammatory disease, development and immune system. Endothelial cell data filtering leads to the identification of several new genes with an endothelial cell signature.

CONCLUSIONS

The chick chorioallantoic wound model allows the identification of gene signatures and pathways involved in GT formation and neoangiogenesis. This may constitute a fertile ground for further studies.

Action of IL-1beta during fracture healing

After bone injury, developmental processes such as endochondral and intramembranous ossification are recapitulated as the skeleton regenerates. In contrast to development, skeletal healing involves inflammation. During the early stages of healing a variety of inflammatory cells infiltrate the injured site, debride the wound, and stimulate the repair process. Little is known about the inflammatory process during bone repair. In this work, we examined the effect of a pro-inflammatory cytokine, Interleukin-1 beta (IL-1beta), on osteoblast and stem cell differentiation and on intramembranous and endochondral ossification, because IL-1beta exerts effects on skeletal homeostasis and is upregulated in response to fracture. We determined that IL-1beta stimulated proliferation of osteoblasts and production of mineralized bone matrix, but suppressed proliferation and inhibited differentiation of bone marrow derived MSCs. We next performed loss- and gain-of-function experiments to determine if altering IL-1beta signaling affects fracture healing. We did not detect any differences in callus, cartilage, and bone matrix production during healing of nonstabilized or stabilized fractures in mice that lacked the IL-1beta receptor compared to wild-type animals. We observed subtle alterations in the healing process after administering IL-1beta during the early phases of repair. At day 10 after injury, the ratio of cartilage to callus was increased, and by day 14, the proportion of cartilage to total callus and to bone was reduced. These changes could reflect a slight acceleration of endochondral ossification, or direct effects on cartilage and bone formation.

Inflammation and epithelial to mesenchymal transition in lung transplant recipients: role in dysregulated epithelial wound repair

Epithelial to mesenchymal transition (EMT) has been implicated in the pathogenesis of obliterative bronchiolitis (OB) after lung transplant. Although TNF-alpha accentuates TGF-beta1 driven EMT in primary human bronchial epithelial cells (PBECs), we hypothesized that other acute pro-inflammatory cytokines elevated in the airways of patients with OB may also accentuate EMT and contribute to dysregulated epithelial wound repair. PBECs from lung transplant recipients were stimulated with TGF-beta1+/-IL-1beta, IL-8, TNF-alpha or activated macrophages in co-culture and EMT assessed. The quality and rate of wound closure in a standardized model of lung epithelial injury was assessed in response to above stimuli. Co-treatment with TGF-beta1+TNF-alpha or IL-1beta significantly accentuates phenotypic and some functional features of EMT compared to TGF-beta1 alone. Co-treatment with TGF-beta1+TNF-alpha or IL-1beta accelerates epithelial wound closure however the quality of repair is highly dysregulated. Co-treatment with TGF-beta1+IL-8 has no significant effect on EMT or the speed or quality of wound healing. Activated macrophages dramatically accentuate TGF-beta1-driven EMT and cause dysregulated wound repair. Crosstalk between macrophage-derived acute inflammation in the airway and elevated TGF-beta1 may favor dysregulated airway epithelial repair and fibrosis in the lung allograft via EMT.

Ghrelin as a novel therapy for radiation combined injury

The threat of nuclear terrorism has led to growing worldwide concern about exposure to radiation. Acute radiation syndrome, or radiation sickness, develops after whole-body or a partial-body irradiation with a high dose of radiation. In the terrorist radiation exposure scenario, however, radiation victims likely suffer from additional injuries such as trauma, burns, wounds or sepsis. Thus, high-dose radiation injuries and appropriate therapeutic interventions must be studied. Despite advances in our understanding of the pathophysiology of radiation injury, very little information is available on the therapeutic approaches to radiation combined injury. In this review, we describe briefly the pathological consequences of ionizing radiation and provide an overview of the animal models of radiation combined injury. We highlight the combined radiation and sepsis model we recently established and suggest the use of ghrelin, a novel gastrointestinal hormone, as a potential therapy for radiation combined injury.

Interleukin-1 participates in the progression from liver injury to fibrosis

Interleukin-1 (IL-1) is rapidly expressed in response to tissue damage; however, its role in coordinating the progression from injury to fibrogenesis is not fully understood. Liver fibrosis is a consequence of the activation of hepatic stellate cells (HSCs), which reside within the extracellular matrix (ECM) of subsinusoids. We have hypothesized that, among the hepatic inflammatory cytokines, IL-1 may directly activate HSCs through autocrine signaling and stimulate the matrix metalloproteinases (MMPs) produced by HSCs within the space of Disse, resulting in liver fibrogenesis. In this study, we first established a temporal relationship between IL-1, MMPs, HSC activation, and early fibrosis. The roles of IL-1 and MMP-9 in HSC activation and fibrogenesis were determined by mice deficient of these genes. After liver injury, IL-1, MMP-9, and MMP-13 levels were found to be elevated before the onset of HSC activation and fibrogenesis. IL-1 receptor-deficient mice exhibited ameliorated liver damage and reduced fibrogenesis. Similarly, advanced fibrosis, as determined by type-I and -III collagen mRNA expression and fibrotic septa, was partially attenuated by the deficiency of IL-1. In the early phase of liver injury, the MMP-9, MMP-13, and TIMP-1 expression correlated well with IL-1 levels. In injured livers, MMP-9 was predominantly colocalized to desmin-positive cells, suggesting that HSCs are MMP-producing cells in vivo. MMP-9-deficient mice were partially protected from liver injury and HSC activation. Thus IL-1 is an important participant, along with other cytokines, and controls the progression from liver injury to fibrogenesis through activation of HSCs in vivo.

Interleukin-1 participates in the progression from liver injury to fibrosis

Interleukin-1 (IL-1) is rapidly expressed in response to tissue damage; however, its role in coordinating the progression from injury to fibrogenesis is not fully understood. Liver fibrosis is a consequence of the activation of hepatic stellate cells (HSCs), which reside within the extracellular matrix (ECM) of subsinusoids. We have hypothesized that, among the hepatic inflammatory cytokines, IL-1 may directly activate HSCs through autocrine signaling and stimulate the matrix metalloproteinases (MMPs) produced by HSCs within the space of Disse, resulting in liver fibrogenesis. In this study, we first established a temporal relationship between IL-1, MMPs, HSC activation, and early fibrosis. The roles of IL-1 and MMP-9 in HSC activation and fibrogenesis were determined by mice deficient of these genes. After liver injury, IL-1, MMP-9, and MMP-13 levels were found to be elevated before the onset of HSC activation and fibrogenesis. IL-1 receptor-deficient mice exhibited ameliorated liver damage and reduced fibrogenesis. Similarly, advanced fibrosis, as determined by type-I and -III collagen mRNA expression and fibrotic septa, was partially attenuated by the deficiency of IL-1. In the early phase of liver injury, the MMP-9, MMP-13, and TIMP-1 expression correlated well with IL-1 levels. In injured livers, MMP-9 was predominantly colocalized to desmin-positive cells, suggesting that HSCs are MMP-producing cells in vivo. MMP-9-deficient mice were partially protected from liver injury and HSC activation. Thus IL-1 is an important participant, along with other cytokines, and controls the progression from liver injury to fibrogenesis through activation of HSCs in vivo.

Differential effects of irradiation with carbon ions and x-rays on macrophage function

Macrophages are potent elicitors of inflammatory reactions that can play both positive and negative roles in radiotherapy. While several studies have investigated the effects of X-rays or gamma-rays on macrophages, virtually no work has been done on the responses of these cells to irradiation with carbon ions. Investigations into the effects of carbon ion irradiation are of particular interest in light of the fact that this type of radiation is being used increasingly for cancer therapy. In the present investigation we compared the effects of 250 kV X-rays with those of 9.8 MeV/u carbon ions on RAW 264.7 macrophages over a wide range of radiation doses. Macrophage functions including vitality, phagocytic activity, production of the proinflammatory cytokines IL-1beta and TNFalpha and production of nitric oxide (NO) were measured. In comparison to lymphocytes and fibroblasts, macrophages showed only a small decrease in vitality after irradiation with either X-rays or carbon ions. Proinflammatory cytokines and NO were induced in macrophages by LPS but not by irradiation alone. X-rays or carbon ions had little modulating effect on LPS-induced TNFalpha production. However, LPS-induced NO increased in a dose dependent manner up to 6-fold after carbon ion irradiation, while X-ray irradiation did not have this effect. Carbon ion irradiation mediated a concomitant decrease in IL-1beta production. Carbon ions also had a greater effect than X-rays in enhancing the phagocytic activity of macrophages. These results underscore the greater potential of carbon ion irradiation with regard to radiobiological effectiveness.

Pravastatin limits radiation-induced vascular dysfunction in the skin

About half of people with cancer are treated with radiation therapy; however, normal tissue toxicity still remains a dose-limiting factor for this treatment. The skin response to ionizing radiation may involve multiple inflammatory outbreaks. The endothelium is known to play a critical role in radiation-induced vascular injury. Furthermore, endothelial dysfunction reflects a decreased availability of nitric oxide. Statins have been reported to preserve endothelial function through their antioxidant and anti-inflammatory activities. In this study, wild type and endothelial nitric oxide synthase (eNOS)(-/-) mice were subjected to dorsal skin irradiation and treated with pravastatin for 28 days. We demonstrated that pravastatin has a therapeutic effect on skin lesions and abolishes radiation-induced vascular functional activation by decreasing interactions between leukocytes and endothelium. Pravastatin limits the radiation-induced increase of blood CCL2 and CXCL1 production expression of inflammatory adhesion molecules such as E-selectin and intercellular adhesion molecule-1, and inflammatory cell migration in tissues. Pravastatin limits the in vivo and in vitro radiation-induced downregulation of eNOS. Moreover, pravastatin has no effect in eNOS(-/-) mice, demonstrating that eNOS plays a key role in the beneficial effect of pravastatin in radiation-induced skin lesions. In conclusion, pravastatin may be a good therapeutic approach to prevent or reduce radiation-induced skin damage.

Medical countermeasures for radiation combined injury: radiation with burn, blast, trauma and/or sepsis. report of an NIAID Workshop, March 26-27, 2007

Non-clinical human radiation exposure events such as the Hiroshima and Nagasaki bombings or the Chernobyl accident are often coupled with other forms of injury, such as wounds, burns, blunt trauma, and infection. Radiation combined injury would also be expected after a radiological or nuclear attack. Few animal models of radiation combined injury exist, and mechanisms underlying the high mortality associated with complex radiation injuries are poorly understood. Medical countermeasures are currently available for management of the non-radiation components of radiation combined injury, but it is not known whether treatments for other insults will be effective when the injury is combined with radiation exposure. Further research is needed to elucidate mechanisms behind the synergistic lethality of radiation combined injury and to identify targets for medical countermeasures. To address these issues, the National Institute of Allergy and Infectious Diseases convened a workshop to make recommendations on the development of animal models of radiation combined injury, possible mechanisms of radiation combined injury, and future directions for countermeasure research, including target identification and end points to evaluate treatment efficacy.

Wound healing is impaired in MyD88-deficient mice: a role for MyD88 in the regulation of wound healing by adenosine A2A receptors

Synergy between Toll-like receptor (TLR) and adenosine A2A receptor (A2AR) signaling switches macrophages from production of inflammatory cytokines such as tumor necrosis factor-alpha to production of the angiogenic growth factor vascular endothelial growth factor (VEGF). We show in this study that this switch critically requires signaling through MyD88, IRAK4, and TRAF6. Macrophages from mice lacking MyD88 (MyD88(-/-)) or IRAK4 (IRAK4(-/-)) lacked responsiveness to TLR agonists and did not respond to A2AR agonists by expressing VEGF. Suppression of TRAF6 expression with siRNA in RAW264.7 macrophages also blocked their response to TLR and A2AR agonists. Excisional skin wounds in MyD88(-/-) mice healed at a markedly slower rate than wounds in wild-type MyD88(+/+) mice, showing delayed contraction, decreased and delayed granulation tissue formation, and reduced new blood vessel density. Although macrophages accumulated to higher levels in MyD88(-/-) wounds than in controls, expression of VEGF and HIF1-alpha mRNAs was elevated in MyD88(+/+) wounds. CGS21680, an A2AR agonist, promoted repair in MyD88(+/+) wounds and stimulated angiogenesis but had no significant effect on healing of MyD88(-/-) wounds. These results suggest that the synergistic interaction between TLR and A(2A)R signaling observed in vitro that switches macrophages from an inflammatory to an angiogenic phenotype also plays a role in wound healing in vivo.

Responses of normal cells to ionizing radiation

Radiation-induced alterations in cellular tissue homeostasis triggered by various molecular responses at the level of inter- and intracellular signaling processes cause both acute and late effects in normal tissue after radiation therapy. Some of the underlying molecular and cellular response pathways leading to radiation-induced tissue remodeling will be discussed, with special emphasis on vascular and parenchymal tissues.

Molecular mechanisms of late normal tissue injury

Irradiation perturbs the homeostatic network linking parenchymal, mesenchymal, and vascular cells within tissues. Normal communication between cells through soluble, matrix, and cell-associated ligands and receptors is altered so as to set in motion a seemingly inexorable series of events aimed at tissue regeneration and healing. In late responding normal tissues where cell death is not compensated for by rapid regeneration, this process unfortunately often culminates in symptomatic complications of radiation exposure. Cytokines and their receptors are prominent in driving the cascade of molecular responses using the balance between seemingly mutually antagonistic molecules to control and direct the healing processes. There is strong evidence from preclinical models for the importance of cytokine-driven pathways in late radiation damage and growing evidence in humans for their relevance to radiation-induced disease. This review aims to show some general aspects of the molecular torrents that drive responses in irradiated tissues before and during the development of late effects. It attempts to collate some of the findings from preclinical models of late lung, central nervous system, skin, and intestinal damage and from clinical studies in the belief that understanding how irradiation perturbs the cellular communication networks will allow rationale intervention for mitigating late radiation tissue damage and carcinogenesis.

Radiation-induced alterations in cytokine production by skin cells

Ionizing radiation exposure of skin results in a cutaneous radiation reaction comprising all pathophysiological reactions and clinical symptoms in irradiated skin. Biological responses of skin occur in a characteristic temporal pattern and mainly depend on radiation quality, dose rate, total dose, and cellular conditions. Immediately after irradiation, production of cytokines by skin cells is initiated and continues as a cascade during all stages of the cutaneous radiation syndrome leading to progressive late symptoms, the predominant of which is fibrosis. Cytokines are important signaling molecules mediating communicative interactions both locally between different cell types within dermal tissues and distantly between organs. Although during recent years much progress has been made in dissecting the complex cytokine network, the role of cytokines in the pathophysiology of the cutaneous radiation reaction is only beginning to be elucidated. Previous studies indicate that the major cytokines in the response of skin cells to ionizing radiation include IL (interleukin)-1, IL-6, tumor necrosis factor (TNF)-alpha, transforming growth factor (TGF)-beta, and the chemokines IL-8 and eotaxin. In this paper, existing data on the radiation-induced modulation of cytokine expression by skin cells are reviewed.