Induction of interleukin 6 by ionizing radiation in a human epithelial cell line: control by corticosteroids

Dietary Oat Bran Reduces Systemic Inflammation in Mice Subjected to Pelvic Irradiation

Patients undergoing radiotherapy to treat pelvic-organ cancer are commonly advised to follow a restricted fiber diet. However, reducing dietary fiber may promote gastrointestinal inflammation, eventually leading to deteriorated intestinal health. The goal of this study was to evaluate the influence of dietary fiber on radiation-induced inflammation. C57BL/6J male mice were fed a High-oat bran diet (15% fiber) or a No-fiber diet (0% fiber) and were either irradiated (32 Gy delivered in four fractions) to the colorectal region or only sedated (controls). The dietary intervention started at 2 weeks before irradiation and lasted for 1, 6, and 18 weeks after irradiation, at which time points mice were sacrificed and their serum samples were assayed for 23 cytokines and chemokines. Our analyses show that irradiation increased the serum cytokine levels at all the time points analyzed. The No-fiber irradiated mice had significantly higher levels of pro-inflammatory cytokines than the High-oat irradiated mice at all time points. The results indicate that a fiber-rich oat bran diet reduces the intensity of radiation-induced inflammation, both at an early and late stage. Based on the results, it seems that the advice to follow a low-fiber diet during radiotherapy may increase the risk of decreased intestinal health in cancer survivors.

Randomized, self-controlled, prospective assessment of the efficacy of mometasone furoate local application in reducing acute radiation dermatitis in patients with head and neck squamous cell carcinomas

BACKGROUND

Acute radiation dermatitis (ARD) is a common adverse effect in patients undergoing radiotherapy. Mometasone furoate cream (MMF) was reported to significantly reduce ARD, especially in breast cancer. Clinically, ARD is more critical and more difficult to prevent in patients with head and neck squamous cell carcinoma (HNSCC) than in those with breast cancer, because a higher dose of radiotherapy is required in HNSCC cases. The aim of this study was to evaluate the effect of MMF local application on radiation dermatitis in patients with HNSCC.

METHODS

HNSCC patients scheduled for bilateral radical radiotherapy to the neck with identical radiation doses were enrolled. One side of the neck skin (test groups) of the patients were randomized to apply a thin layer of MMF once a day from the date of first radiotherapy until either 2 weeks after end of radiotherapy or until the test side skin developed ARD lesions, while the other side of neck (control groups) didn't apply any medication. The severity of ARD was evaluated weekly by using the modified radiation therapy oncology group score, pain intensity, and itch stages.

RESULTS

Forty-one patients (82 targets) were analyzed. There was a significant difference between the ARD scores on the test side and the control side. MMF reduced the stages of ARD when the radiotherapy dose was <6000 cGY (P = .01) but showed no improvement when the dose was ≥6000 cGY (P = .699). Compared to the control side, local application of MMF significantly reduced the itch and pain scores of the test side skin regardless of the radiotherapy dose and ARD stage (P < .001) during radiotherapy.

CONCLUSIONS

This study showed that MMF inunction after high-dose radiotherapy (>50 Gy) can prevent ARD, especially when the radiation dose is <6000 cGY.

Radiation-induced skin reactions: mechanism and treatment

Radiotherapy (RT) is a major treatment for malignant tumors. The latest data show that >70% of patients with malignant tumors need RT at different periods. Skin changes can be experienced by up to 95% of patients who underwent RT. Inflammation and oxidative stress (OS) have been shown to be generally associated with radiation-induced skin reactions (RISRs). Inflammatory response and OS interact and promote each other during RISRs. Severe skin reactions often have a great impact on the progress of RT. The treatment of RISRs is particularly critical because advanced RT technology can also lead to skin reactions. RISRs are classified into acute and chronic reactions. The treatment methods for acute RISRs include steroid treatment, creams, ointments, and hydrocolloid dressings, depending on the reaction grading. Chronic RISRs includes chronic ulcerations, telangiectasias, and fibrosis of the skin, and advanced treatments such as mesenchymal stem cells, hyperbaric oxygen therapy, superoxide dismutase, and low-intensity laser therapy can be considered. Here, we review and summarize the important mechanisms that cause RISRs as well as the standard and advanced treatments for RISRs.

Involvement of SULF2 in y-irradiation-induced invasion and resistance of cancer cells by inducing IL-6 expression

Cancer cells that survive radiotherapy often display enhanced invasiveness and resistance to death stimuli. Previous findings have suggested that ionizing radiation (IR) induces such undesirable effects by stimulating the STAT3/Bcl-XL pathway. To identify novel cellular components that mediate these actions of IR, we irradiated lung cancer cells with sublethal doses of y-rays and screened for the induction of IR-responsive genes by microarray analysis. The genes encoding 2 extracellular proteins, SULF2 and IL-6, were found to be upregulated, and these results were confirmed by polymerase chain reactions and western blot analyses. Because the IR-mediated induction of SULF2 was a novel finding, we also confirmed the phenomenon in vivo using xenograft tumors in mice. Analyses of signaling processes revealed that IR induced SULF2 expression via p53, which then promoted IL-6 expression by stabilizing β-catenin, followed by stimulation of the STAT3/Bcl-XL pathway. Consistently, both SULF2 and IL-6 mediated IR-induced invasion and resistance to death stimuli. To investigate whether SULF2 contributes to IR-induced tumor metastasis, we irradiated tumors in mice with sublethal doses of IR. This treatment promoted the entry of tumor cells into the blood stream (intravasation), which was abolished by downregulating SULF2 expression in tumor cells. These results demonstrated that SULF2 can mediate the detrimental effects of IR in vivo. Therefore, SULF2 may be potentially used as a therapeutic and diagnostic target to predict and overcome the malignant effects of IR, particularly in tumors expressing p53 wild-type.

Immunotherapy Combined with Large Fractions of Radiotherapy: Stereotactic Radiosurgery for Brain Metastases-Implications for Intraoperative Radiotherapy after Resection

Brain metastases (BM) affect approximately a third of all cancer patients with systemic disease. Treatment options include surgery, whole-brain radiotherapy, or stereotactic radiosurgery (SRS) while chemotherapy has only limited activity. In cases where patients undergo resection before irradiation, intraoperative radiotherapy (IORT) to the tumor bed may be an alternative modality, which would eliminate the repopulation of residual tumor cells between surgery and postoperative radiotherapy. Accumulating evidence has shown that high single doses of ionizing radiation can be highly efficient in eliciting a broad spectrum of local, regional, and systemic tumor-directed immune reactions. Furthermore, immune checkpoint blockade (ICB) has proven effective in treating antigenic BM and, thus, combining IORT with ICB might be a promising approach. However, it is not known if a low number of residual tumor cells in the tumor bed after resection is sufficient to act as an immunizing event opening the gate for ICB therapies in the brain. Because immunological data on tumor bed irradiation after resection are lacking, a rationale for combining IORT with ICB must be based on mechanistic insight from experimental models and clinical studies on unresected tumors. The purpose of the present review is to examine the mechanisms by which large radiation doses as applied in SRS and IORT enhance antitumor immune activity. Clinical studies on IORT for brain tumors, and on combined treatment of SRS and ICB for unresected BM, are used to assess the safety, efficacy, and immunogenicity of IORT plus ICB and to suggest an optimal treatment sequence.

Acute radiation dermatitis in breast cancer patients: challenges and solutions

Nearly all women who receive radiotherapy (RT) for breast cancer experience some degree of radiation dermatitis. However, evidence describing the appropriate management of radiation dermatitis is often lacking or contradictory. Here, we summarize the available literature regarding radiation dermatitis causes, the presentation and timing of symptoms, methods for dermatitis assessment and prevention, and review evidence-based management strategies.

Evaluating biomarkers to model cancer risk post cosmic ray exposure

Robust predictive models are essential to manage the risk of radiation-induced carcinogenesis. Chronic exposure to cosmic rays in the context of the complex deep space environment may place astronauts at high cancer risk. To estimate this risk, it is critical to understand how radiation-induced cellular stress impacts cell fate decisions and how this in turn alters the risk of carcinogenesis. Exposure to the heavy ion component of cosmic rays triggers a multitude of cellular changes, depending on the rate of exposure, the type of damage incurred and individual susceptibility. Heterogeneity in dose, dose rate, radiation quality, energy and particle flux contribute to the complexity of risk assessment. To unravel the impact of each of these factors, it is critical to identify sensitive biomarkers that can serve as inputs for robust modeling of individual risk of cancer or other long-term health consequences of exposure. Limitations in sensitivity of biomarkers to dose and dose rate, and the complexity of longitudinal monitoring, are some of the factors that increase uncertainties in the output from risk prediction models. Here, we critically evaluate candidate early and late biomarkers of radiation exposure and discuss their usefulness in predicting cell fate decisions. Some of the biomarkers we have reviewed include complex clustered DNA damage, persistent DNA repair foci, reactive oxygen species, chromosome aberrations and inflammation. Other biomarkers discussed, often assayed for at longer points post exposure, include mutations, chromosome aberrations, reactive oxygen species and telomere length changes. We discuss the relationship of biomarkers to different potential cell fates, including proliferation, apoptosis, senescence, and loss of stemness, which can propagate genomic instability and alter tissue composition and the underlying mRNA signatures that contribute to cell fate decisions. Our goal is to highlight factors that are important in choosing biomarkers and to evaluate the potential for biomarkers to inform models of post exposure cancer risk. Because cellular stress response pathways to space radiation and environmental carcinogens share common nodes, biomarker-driven risk models may be broadly applicable for estimating risks for other carcinogens.

Particle Radiation-Induced Nontargeted Effects in Bone-Marrow-Derived Endothelial Progenitor Cells

Bone-marrow- (BM-) derived endothelial progenitor cells (EPCs) are critical for endothelial cell maintenance and repair. During future space exploration missions astronauts will be exposed to space irradiation (IR) composed of a spectrum of low-fluence protons ((1)H) and high charge and energy (HZE) nuclei (e.g., iron-(56)Fe) for extended time. How the space-type IR affects BM-EPCs is limited. In media transfer experiments in vitro we studied nontargeted effects induced by (1)H- and (56)Fe-IR conditioned medium (CM), which showed significant increase in the number of p-H2AX foci in nonirradiated EPCs between 2 and 24 h. A 2-15-fold increase in the levels of various cytokines and chemokines was observed in both types of IR-CM at 24 h. Ex vivo analysis of BM-EPCs from single, low-dose, full-body (1)H- and (56)Fe-IR mice demonstrated a cyclical (early 5-24 h and delayed 28 days) increase in apoptosis. This early increase in BM-EPC apoptosis may be the effect of direct IR exposure, whereas late increase in apoptosis could be a result of nontargeted effects (NTE) in the cells that were not traversed by IR directly. Identifying the role of specific cytokines responsible for IR-induced NTE and inhibiting such NTE may prevent long-term and cyclical loss of stem and progenitors cells in the BM milieu.

Effects of Ligustrazine on DNA damage and apoptosis induced by irradiation

Ligustrazine has been used to treat heart and blood vessel disease in China. In the present study, we investigated the potential action of Ligustrazine as a component of chuanxiong (a Chinese herb) in scavenging hydroxyl radical and superoxide radical as indicated in the ESR spin-trapping measurement. Treatment of Ligustrazine in mice decreased mortality after whole body γ-irradiation. The anti-radiation action of Ligustrazine was studied by measuring DNA damage (Comet assay and γ-H2AX formation) and apoptosis induced by irradiation. It was triggered by altering the level of DNA-PKcs protein, a critical component of DNA double-strand break (DSB) repair pathways in mice after irradiation. Consistently, the phosphorylation of Akt protein, a mediator of survival signaling, was concurrently increased by Ligustrazine treatment. Additionally, the cytokines along with the phosphorylation of the p38 protein which is activated by a variety of environmental stresses and inflammatory cytokines decreased in the Ligustrazine-treated group as compared to irradiation group. Our results suggest that Ligustrazine has radioprotective effect through its capabilities as a powerful antioxidant, in reducing reactive oxygen species (ROS) level induced by irradiation, minimizing DNA damage and apoptosis, and activating survival signal Akt pathways. This study will be of value in the development of novel radioprotective compounds.

3M Cavilon No-Sting Barrier Film or topical corticosteroid (mometasone furoate) for protection against radiation dermatitis: A clinical trial

BACKGROUND/PURPOSE

Evidence on the prevention of radiation dermatitis is lacking. The aim of this study was to investigate the effect of 3M Cavilon No Sting Barrier Film and topical corticosteroids on irradiated skin.

METHODS

Thirty-nine postoperative breast cancer patients were randomized into three groups for intraindividual comparison (skin to be irradiated was divided into 2 parts): (1) 3M No Sting Barrier Film versus no treatment; (2) corticosteroid versus no treatment; and (3) corticosteroid versus 3M No Sting Barrier Film. The primary end points monitored were the time to first occurrence of grade 1 pruritus, pain score of 3 and grade 2 radiation dermatitis. The secondary end points studied were the incidence of grade 3 radiation dermatitis and total pain scores. Data analysis was done using the SPSS software version 10.

RESULTS

Skin given the 3M barrier film experienced a later occurrence of pruritus compared to both corticosteroids and untreated, although this was statistically insignificant. Corticosteroids delayed the time to occurrence of grade 2 dermatitis compared to both untreated skin and 3M barrier film, (mean day of onset = corticosteroid: 52 vs. untreated: 43, p = 0.092; corticosteroid: 53.4 vs. 3M barrier film: 44.5, p = 0.002, t test). Skin given corticosteroids had the lowest incidence of grade 3 dermatitis among all three conditions, although the differences were statistically insignificant. No statistically significant differences were noted in total pain scores.

CONCLUSION

The 3M barrier film may be helpful against dermatitis associated pruritus. Corticosteroids may delay the time of onset of severe skin reactions and also reduce the incidence of severe radiation dermatitis.

Interleukin-6 counteracts therapy-induced cellular oxidative stress in multiple myeloma by up-regulating manganese superoxide dismutase

IL (interleukin)-6, an established growth factor for multiple myeloma cells, induces myeloma therapy resistance, but the resistance mechanisms remain unclear. The present study determines the role of IL-6 in re-establishing intracellular redox homoeostasis in the context of myeloma therapy. IL-6 treatment increased myeloma cell resistance to agents that induce oxidative stress, including IR (ionizing radiation) and Dex (dexamethasone). Relative to IR alone, myeloma cells treated with IL-6 plus IR demonstrated reduced annexin/propidium iodide staining, caspase 3 activation, PARP [poly(ADP-ribose) polymerase] cleavage and mitochondrial membrane depolarization with increased clonogenic survival. IL-6 combined with IR or Dex increased early intracellular pro-oxidant levels that were causally related to activation of NF-κB (nuclear factor κB) as determined by the ability of N-acetylcysteine to suppress both pro-oxidant levels and NF-κB activation. In myeloma cells, upon combination with hydrogen peroxide treatment, relative to TNF (tumour necrosis factor)-α, IL-6 induced an early perturbation in reduced glutathione level and increased NF-κB-dependent MnSOD (manganese superoxide dismutase) expression. Furthermore, knockdown of MnSOD suppressed the IL-6-induced myeloma cell resistance to radiation. MitoSOX Red staining showed that IL-6 treatment attenuated late mitochondrial oxidant production in irradiated myeloma cells. The present study provides evidence that increases in MnSOD expression mediate IL-6-induced resistance to Dex and radiation in myeloma cells. The results of the present study indicate that inhibition of antioxidant pathways could enhance myeloma cell responses to radiotherapy and/or chemotherapy.

Dexamethasone-induced oxidative stress enhances myeloma cell radiosensitization while sparing normal bone marrow hematopoiesis

Dexamethasone (Dex) and radiation therapy are established modalities in multiple myeloma. In this study, we propose a novel combination of Dex plus radiation that shows superior clonogenic cell killing and apoptosis of myeloma cells and selectively eliminates myeloma cells when cocultured with bone marrow stromal cells (BMSCs). Dex was found to inhibit the release of interleukin-6 from irradiated BMSCs, which is an established myeloma cell proproliferative cytokine. In 5TGM1 model, the combination of Dex with skeletal targeted radiotherapy (153-Sm-EDTMP) prolonged median survival time and inhibited radiation-induced myelosuppression. A two-cycle treatment of Dex plus 153-Sm-EDTMP was well tolerated and further improved median survival time. Mechanistically, Dex increased superoxide and hydrogen peroxide production and augmented radiation-induced oxidative stress and cell death of myeloma cells. In contrast, Dex inhibited radiation-induced increase in pro-oxidant levels and enhanced the clonogenic survival in normal hematopoietic stem and progenitor cells. Treatment with either N-acetylcysteine or the combination of polyethylene glycol (PEG)-conjugated copper, zinc-superoxide dismutase, and PEG-catalase significantly protected myeloma cells from Dex-induced clonogenic death. Overall, these results demonstrate that Dex in combination with radiotherapy enhances the killing of myeloma cells while protecting normal bone marrow hematopoiesis through a mechanism that involves selective increases in oxidative stress.

Regulation of glucocorticoid receptor activity by a stress responsive transcriptional cofactor

The activity of the glucocorticoid receptor (GR) is modulated by posttranslational modifications, protein stability, and cofactor recruitment. In this report, we investigated the role of the stress-responsive activator of p300/tetratricopeptide repeat domain 5 (TTC5), in the regulation of the GR. TTC5 is a member of the TTC family of proteins and has previously been shown to participate in the cellular response to DNA damage and heat shock. Here, we demonstrate that TTC5 is an important cofactor for the nuclear hormone receptors GR and estrogen receptor. GR and TTC5 interact through multiple tetratricopeptide repeat and LXXLL motifs. TTC5 stabilizes GR and increases its half-life, through a proteasome-dependent process and by inhibiting the actions of the ubiquitin ligase murine double minute 2. Cellular stress, including DNA damage, proteasome inhibition, and heat shock, modulates the interaction pattern of GR/TTC5, thereby altering GR stability and transcriptional activity. Furthermore, GR transcriptional activity is regulated by TTC5 in both a positive and negative fashion under DNA damage conditions in a target gene-specific way. In this report we provide evidence supporting the notion that TTC5 is a novel cofactor regulating GR function in a stress-dependent manner.

High-throughput antibody-based assays to identify and quantify radiation-responsive protein biomarkers

PURPOSE

After a radiological 'dirty bomb' incident in a major metropolitan center, substantial numbers of people may be exposed to radiation. However, only a fraction of those individuals will need urgent medical attention. Consequently, a rapid screening test is needed to identify those people who require immediate treatment.

MATERIAL AND METHODS

Ten normal human cell lines were screened by enzyme-linked immunosorbent assay (ELISA) for the expression of a dozen secreted cytokines that have been reported to have changes in protein or mRNA levels at 1, 2, and 3 days after 0-10 Gy irradiation using (137)Cs gamma rays at 0.82 Gy min(-1). After this systematic in vitro screen, we measured changes in the level of a subset of these candidate proteins in plasma from irradiated C57BL/6 mice (n = 3 per group), comparing shams with a single radiation dose (5 Gy X-rays) at 3.7 Gy min(-1) at 6 h after irradiation.

RESULTS

We identified four cytokine molecules that had altered levels after radiation exposure, one of which, Interleukin (IL) 6, was consistently elevated after irradiation in vitro and in vivo.

CONCLUSIONS

Our findings underscore the potential for IL6 as a marker for an immunoassay-based, rapid, high-throughput biodosimeter.

Candidate protein biodosimeters of human exposure to ionizing radiation

PURPOSE

To conduct a literature review of candidate protein biomarkers for individual radiation biodosimetry of exposure to ionizing radiation.

MATERIALS AND METHODS

Reviewed approximately 300 publications (1973 - April 2006) that reported protein effects in mammalian systems after either in vivo or in vitro radiation exposure.

RESULTS

We found 261 radiation-responsive proteins including 173 human proteins. Most of the studies used high doses of ionizing radiation (>4 Gy) and had no information on dose- or time-responses. The majority of the proteins showed increased amounts or changes in phosphorylation states within 24 h after exposure (range: 1.5- to 10-fold). Of the 47 proteins that are responsive at doses of 1 Gy and below, 6 showed phosphorylation changes at doses below 10 cGy. Proteins were assigned to 9 groups based on consistency of response across species, dose- and time-response information and known role in the radiation damage response.

CONCLUSIONS

ATM (Ataxia telengiectasia mutated), H2AX (histone 2AX), CDKN1A (Cyclin-dependent kinase inhibitor 1A), and TP53 (tumor protein 53) are top candidate radiation protein biomarkers. Furthermore, we recommend a panel of protein biomarkers, each with different dose and time optima, to improve individual radiation biodosimetry for discriminating between low-, moderate-, and high-dose exposures. Our findings have applications for early triage and follow-up medical assessments.

Study of qingre liyan decoction in treating and preventing acute radioactive oral mucositis

OBJECTIVE

To study the effect of Qingre Liyan Decoction (QRLYD) in the prevention and treatment of acute radiative oral mucositis (AROM), and to explore the mechanism of QRLYD by detecting epidermal growth factor (EGF) and T lymphocytes (CD3, CD4, and CD8).

METHODS

Sixty patients conforming with the standard were randomly assigned to two groups, 30 patients in each group. Patients in the trial group were treated with QRLYD, and those in the control group were treated with Dobell's solution, both groups receiving conventional radiation treatment. The treatment course for both groups was 6 weeks on average. Blood routine test, CD3, CD4, and CD8 in the peripheral blood and EGF in the saliva were detected one day before and on the 14th and 28th day of radio-therapy.

RESULTS

Patients in the trial group were in good condition with normal spirits and intake of food and drinks. The incidence of AROM is lower and the effect in preventing AROM is higher in the trial group than those in the control group (P<0.05). The EGF in saliva, and CD4 and CD8 in the blood of patients in the trial group were higher than those in the control group (P<0.05).

CONCLUSION

QRLYD can cure and prevent AROM. The mechanism may be related with its effects in enhancing body immunity and promoting salivary EGF.

The clinical and histopathological effects of prednisone on acute radiation-induced dermatitis in dogs: a placebo-controlled, randomized, double-blind, prospective clinical trial

This study evaluated and compared the clinical and histopathological effects of prednisone on acute radiation-induced dermatitis (ARID) in dogs treated with 48 Gray of fractionated irradiation targeted to the skin surface. The study was designed as a double-blind, randomized, placebo-controlled prospective clinical trial. Twenty-two otherwise healthy companion dogs completed the clinical study. Three dogs were excluded from complete histopathological analysis because the owner declined one (one dog) or both (two dogs) biopsies. The study duration for each dog was 36 days from the start of radiation therapy (RT) to the first re-examination post RT. Dogs were treated with either oral prednisone at 0.5 mg kg(-1) or sugar pill, daily. All dogs received 48 Gray of fractionated, standardized RT, beginning 2 weeks after tumour excision. Acute Radiation Morbidity Scores, Cutaneous Toxicity Extent and Severity scores, digital images, and impression cytology were carried out on days 1, 8, 15, 22 and 36. Four-millimetre skin specimens from days 15 (RT-11) and 36 (2 weeks after the last RT dose) were scored by a pathologist and a dermatologist, blind to specimen identity. A one-way analysis of variance for longitudinal data was used to compare scores between groups. Spearman's rho correlation coefficient was used to measure strength of association between clinical and histopathology scores (HPS). There was no significant difference in CUTES, AMS or HPS scores between groups. There was a strong correlation between clinical and HPS scores. Prednisone did not decrease ARID severity clinically or histopathologically.

Non-invasive time-lapsed monitoring and quantification of engineered bone-like tissue

The formation of bone-like tissue from human mesenchymal stem cells (hMSC) cultured in osteogenic medium on silk fibroin scaffolds was monitored and quantified over 44 days in culture using non-invasive time-lapsed micro-computed tomography (microCT). Each construct was imaged nine times in situ. From microCT imaging, detailed morphometrical data on bone volume density, surface-to-volume ratio, trabecular thickness, trabecular spacing, and the structure model index and tissue mineral density were obtained. microCT irradiation did not impact the osteogenic performance of hMSCs based on DNA content, alkaline phosphatase activity, and calcium deposition when compared to non-exposed control samples. Bone-like tissue formation initiated at day 10 of the culture with the deposition of small mineralized clusters. Tissue mineral density increased linearly over time. The surface-to-volume ratio of the bone-like tissues converged asymptotically to 26 mm(-1). Although in vitro formation of bone-like tissue started from clusters, the overall bone volume was not predictable from the time, number, and size of initially formed bone-like clusters. Based on microstructural analysis, the morphometry of the tissue-engineered constructs was found to be in the range of human trabecular bone. In future studies, non-invasive, time-lapsed monitoring may enable researchers to culture tissues in vitro, right until the development of a desired morphology is accomplished. Our data demonstrate the feasibility of qualitatively and quantitatively detailing the spatial and temporal mineralization of bone-like tissue formation in tissue engineering.

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.

Collapse of Skin Antioxidant Status during the Subacute Period of Cutaneous Radiation Syndrome: A Case Report

This case report describes a patient suffering from accidental cutaneous radiation syndrome. Clinical symptoms were characterized by the presence of moist epidermal denudation over approximately 8% of the body surface without signs of necrosis 88 days after radiation exposure. The skin transcriptional profile was obtained and provides a comprehensive overview of the changes in gene expression associated with skin wound healing after irradiation. In particular, our data show a specific set of genes, i.e. SOD1, GPX1, TDX1, TDX2 and HSP60, implicated in the redox control of normal skin repair after radiation exposure, whereas HOX1 and HOX2 were involved in the pathological skin repair. A reduction in the antioxidant capacity of the irradiated tissue concomitant with a progressive establishment of an uncontrolled inflammatory response was noted. Our data corroborate the hypothesis that ROS modulation is a key element of the healing response after cutaneous exposure to radiation and that the collapse of skin antioxidant status interferes directly with wound healing in skin after radiation exposure. Thus a better understanding of the molecular events through which oxidative stress modulates the healing response could result in a more rational therapeutic approach to the pathological process induced after exposure of skin to radiation.

Intercellular adhesion molecule-1: a consistent inflammatory marker of the cutaneous radiation reaction both in vitro and in vivo

BACKGROUND

Radiation damage to skin is a key diagnostic and prognostic parameter for patients accidentally exposed to radiation. Moreover, skin is a target organ for crucial side-effects of routine radiotherapy. The pathophysiology of the cutaneous radiation reaction is in many respects still unknown. The acute inflammatory radiation reaction of skin has been shown to involve alterations in cell-cell and cell-matrix interactions, which are mediated by cellular adhesion molecules.

OBJECTIVES

To evaluate the effect of ionizing radiation on intercellular adhesion molecule-1 (ICAM-1) expression in human skin cells.

METHODS

Dermal monolayer cells, a three-dimensional skin model and skin biopsies were investigated for ICAM-1 expression after ionizing radiation using flow cytometry, quantitative reverse transcription-polymerase chain reaction and immunohistochemistry. ICAM-1 expression in monolayer cells pretreated with protein kinase inhibitors and dexamethasone prior to irradiation was analysed by flow cytometry.

RESULTS

Using different sources of skin cells, we demonstrated a consistent upregulation of both ICAM-1 mRNA and protein expression by ionizing radiation. Blocking experiments revealed that tumour necrosis factor-alpha, another ICAM-1 inducer, does not account for the effect of radiation. Radiation-induced upregulation of ICAM-1 expression was significantly attenuated by inhibitors to protein kinase C, mitogen-activated protein (MAP) ERK kinase, p38 MAP kinase and phosphatidylinositol 3-kinase. The anti-inflammatory agent dexamethasone suppressed the effect of radiation on ICAM-1 expression, suggesting its usefulness to treat the cutaneous radiation reaction.

CONCLUSIONS

Our data suggest that ICAM-1 is a consistent inflammatory parameter of the cutaneous radiation reaction both in vitro and in vivo that might provide new therapeutic options for diagnosis and treatment of effects of radiation.

Prostaglandin E receptor EP3 deficiency modifies tumor outcome in mouse two-stage skin carcinogenesis

We have recently shown that the prostaglandin E(2) (PGE(2)) receptor EP(3) plays an important role in suppression of colon cancer cell proliferation and that its deficiency enhances late stage colon carcinogenesis. Here we examined the effects of EP(3)-deficiency on two-stage skin carcinogenesis. 7,12-Dimethylbenz[a]anthracene (50 microg/200 microl of acetone) was thus applied to the back skin of female EP(3)-knockout and wild-type mice at 8 weeks of age, followed by treatment with 12-O-tetradecanoylphorbol-13-acetate (5 microg/200 microl of acetone) twice a week for 25 weeks. First tumor appearance was observed in EP(3)-knockout mice at week 10, which was 3 weeks later than in EP(3) wild-type mice, and multiplicity observed at week 11 was significantly lower in the EP(3)-knockout case. However, histological examination showed that the tumor incidence and multiplicity at week 25 were not significantly changed in knockout mice and wild-type mice (incidence, 19/19 versus 23/24; multiplicity, 3.58 +/- 0.51 versus 3.17 +/- 0.63, respectively). Interestingly, there were no squamous cell carcinomas (SCCs) in the EP(3)-knockout mice, while SCCs were observed in 3 out of 24 wild-type mice. Furthermore, benign keratoacanthomas only developed in EP(3)-knockout mice (6/19 versus 0/24, P < 0.01). The results suggest that PGE(2) receptor EP(3) signaling might contribute to development of SCCs in the skin.

Skin toxicity during breast irradiation: pathophysiology and management

Radiotherapy is a critical component in the treatment of breast cancer, a disease that is estimated to have affected 203,500 US women in 2002. According to the data from some series, an estimated 90% of patients treated with radiotherapy for breast cancer will develop a degree of radiation-induced dermatitis. This review describes the indications and techniques of radiotherapy for breast cancer. The pathophysiology, clinical presentation, and contributing factors of radiation-related skin injury are discussed. A review of recent clinical research addressing skin toxicity is provided.

Fibrosis and cytokine mechanisms: Relevant in hadron therapy?

BACKGROUND

Cytokines are important for signalling between cells and tissues and constitute a humoral component of the response of cells and tissues to radiotherapy. Although several cytokines have been implicated in mediating radiation-induced reactions of normal tissues to both conventional photon and heavy ion irradiation, the mechanisms are only beginning to be elucidated.

MATERIAL AND METHODS

Published and own data on radiation-induced cytokine expression from cell culture and clinical studies are reviewed. Current models of cytokine-mediated multicellular interactions in radiation-induced reactions are presented.

RESULTS AND CONCLUSION

The major cytokines in the radiation response of non-hemopoietic tissues include IL-6, IL-1, TNF-alpha and TGF-beta. Different cell types interact via cytokines in a complex network of effector and receptor cells, including inflammatory cells, tissue-specific functional cells and fibroblasts. TGF-beta appears to be of particular importance in the development of late reactions to radiation therapy, such as fibrosis, in response to both conventional therapy as well as hadron therapy.

Ionizing radiation affects human MART-1 melanoma antigen processing and presentation by dendritic cells

Radiation is generally considered to be an immunosuppressive agent that acts by killing radiosensitive lymphocytes. In this study, we demonstrate the noncytotoxic effects of ionizing radiation on MHC class I Ag presentation by bone marrow-derived dendritic cells (DCs) that have divergent consequences depending upon whether peptides are endogenously processed and loaded onto MHC class I molecules or are added exogenously. The endogenous pathway was examined using C57BL/6 murine DCs transduced with adenovirus to express the human melanoma/melanocyte Ag recognized by T cells (AdVMART1). Prior irradiation abrogated the ability of AdVMART1-transduced DCs to induce MART-1-specific T cell responses following their injection into mice. The ability of these same DCs to generate protective immunity against B16 melanoma, which expresses murine MART-1, was also abrogated by radiation. Failure of AdVMART1-transduced DCs to generate antitumor immunity following irradiation was not due to cytotoxicity or to radiation-induced block in DC maturation or loss in expression of MHC class I or costimulatory molecules. Expression of some of these molecules was affected, but because irradiation actually enhanced the ability of DCs to generate lymphocyte responses to the peptide MART-1(27-35) that is immunodominant in the context of HLA-A2.1, they were unlikely to be critical. The increase in lymphocyte reactivity generated by irradiated DCs pulsed with MART-1(27-35) also protected mice against growth of B16-A2/K(b) tumors in HLA-A2.1/K(b) transgenic mice. Taken together, these results suggest that radiation modulates MHC class I-mediated antitumor immunity by functionally affecting DC Ag presentation pathways.

A Sense of Danger from Radiation1

Tissue damage caused by exposure to pathogens, chemicals and physical agents such as ionizing radiation triggers production of generic "danger" signals that mobilize the innate and acquired immune system to deal with the intrusion and effect tissue repair with the goal of maintaining the integrity of the tissue and the body. Ionizing radiation appears to do the same, but less is known about the role of "danger" signals in tissue responses to this agent. This review deals with the nature of putative "danger" signals that may be generated by exposure to ionizing radiation and their significance. There are a number of potential consequences of "danger" signaling in response to radiation exposure. "Danger" signals could mediate the pathogenesis of, or recovery from, radiation damage. They could alter intrinsic cellular radiosensitivity or initiate radioadaptive responses to subsequent exposure. They may spread outside the locally damaged site and mediate bystander or "out-of-field" radiation effects. Finally, an important aspect of classical "danger" signals is that they link initial nonspecific immune responses in a pathological site to the development of specific adaptive immunity. Interestingly, in the case of radiation, there is little evidence that "danger" signals efficiently translate radiation-induced tumor cell death into the generation of tumor-specific immunity or normal tissue damage into autoimmunity. The suggestion is that radiation-induced "danger" signals may be inadequate in this respect or that radiation interferes with the generation of specific immunity. There are many issues that need to be resolved regarding "danger" signaling after exposure to ionizing radiation. Evidence of their importance is, in some areas, scant, but the issues are worthy of consideration, if for no other reason than that manipulation of these pathways has the potential to improve the therapeutic benefit of radiation therapy. This article focuses on how normal tissues and tumors sense and respond to danger from ionizing radiation, on the nature of the signals that are sent, and on the impact on the eventual consequences of exposure.

Effect of steroidal and non-steroidal anti-inflammatory drugs in combination with long-acting oxytetracycline on non-specific immunity of calves suffering from enzootic bronchopneumonia

The aim of this paper was to compare the effect of flumethasone and meloxicam in combination with oxytetracycline on clinical and immunological parameters of calves suffering from enzootic bronchopneumonia. The study was performed on 30 Black-and-White Lowland Breed calves with clinical signs of enzootic bronchopneumonia divided randomly into three equal groups and, respectively, treated with-Group I: oxytetracycline and meloxicam; Group II: oxytetracycline and flumethasone; Group III (control): oxytetracycline only. Treatment of calves with the combination of oxytetracycline and meloxicam (Group I) caused a significantly faster, in comparison to other groups, improvement in the clinical illness index score (CIIS: cough, nasal discharge, dyspnea, depression and anorexia) and a faster normalization of body temperature. A slow decrease in white blood cell (WBC) count, the number of neutrophils, MID (mixed number of monocytes, eosinophils and basophils) and in the individual number of monocytes (CD14/CD45 positive cells) was observed in Groups I and III. In the blood of the calves which received oxytetracycline and flumethasone (Group II), leukocytosis, neutrophilia and monocytosis with concomitant lymphopenia and a low number of T cells (CD2+) was observed. Moreover, the calves treated with flumethasone exhibited a decrease in gamma-globulin concentration, and phagocytic parameters. Both drugs, flumethasone and meloxicam slightly decreased tumor necrosis factor (TNF) but meloxicam slightly increased the levels of interferon (IFN) in sera and in bronchoalveolar lavages (BALs). These results suggest that the combination of meloxicam with an antibiotic in calves suffering from enzootic bronchopneumonia is superior to the antibiotic alone and also to the combination of the antibiotic with flumethasone.

The role of the ubiquitin/proteasome system in cellular responses to radiation

In the last few years, the ubiquitin(Ub)/proteasome system has become increasingly recognized as a controller of numerous physiological processes, including signal transduction, DNA repair, chromosome maintenance, transcriptional activation, cell cycle progression, cell survival, and certain immune cell functions. This is in addition to its more established roles in the removal of misfolded, damaged, and effete proteins. This review examines the role of the Ub/proteasome system in processes underlying the classical effects of irradiation on cells, such as radiation-induced gene expression, DNA repair and chromosome instability, oxidative damage, cell cycle arrest, and cell death. Furthermore, recent evidence suggests that the proteasome is a redox-sensitive target for ionizing radiation and other oxidative stress signals. In other words, the Ub/proteasome system may not simply be a passive player in radiation-induced responses, but may modulate them. The extent of the modulation will be influenced by the functional and structural diversity that is expressed by the system. Cell types vary in the Ub/proteasome structures they possess and the level at which they function, and this changes as they go from the normal to the cancerous condition. Cancer-related functional changes within the Ub/proteasome system may therefore present unique targets for cancer therapy, especially when targeting agents are used in combination with radio- or chemotherapy. The peptide boronic acid compound PS-341, which was designed to inhibit proteasome chymotryptic activity, is in clinical trials for the treatment of solid and hematogenous tumors. It has shown some efficacy on its own and in combination with chemotherapy. Preclinical studies have shown that PS-341 will also potentiate the cytotoxic effects of radiation therapy. In addition, other drugs in common clinical use have been shown to affect proteasome function, and their activities may be valuably reconsidered from this perspective.

The radioprotective activities of turpentine-induced inflammation and alpha2-macroglobulin: the effect of dexamethasone on the radioprotective efficacy of the inflammation

This work was aimed at the radioprotective efficacy of turpentine oil (TO), alpha2-Macroglobulin (alpha2-M), Amifostine (Ami) and/or dexamethasone (Dex). These agents were administrated, alone or in combination, prior to irradiation of rats with 6.7 Gy (LD(50/30)). The survival was recorded daily for 4 weeks after irradiation and body weight, peripheral leukocytes and thrombocytes were measured. The plasma concentration of alpha2-M and other acute phase proteins were determined by crossed immunoelectrophoresis. All rats receiving alpha2-M and Ami alone or in combination survived the radiation injury, whereas the rate of survival of TO-treated rats was 90%. Radiation and therapy-induced changes in the expression of acute phase protein genes were atypical for the acute phase reaction. Dex alone was lethal for 45% and 55% of control and irradiated rats, respectively. Pretreatment with 1mg Dex reduced radioprotective efficacy of TO and Ami to 30% and 40%, respectively. Given together TO and Ami provided 70% protection to rats receiving Dex. The TO and alpha2-M enhanced the rate of survival from 50% to 90% and 100%, respectively. In the presence of 1mg Dex the TO-induced radioprotectors and Ami exhibited radiosensitizing rather than radioprotecting activities.

The action of a dietary retinoid on gene expression and cancer induction in electron-irradiated rat skin

Current models of radiation carcinogenesis generally assume that the DNA is damaged in a variety of ways by the radiation and that subsequent cell divisions contribute to the conversion of the damage to heritable mutations. Cancer may seem complex and intractable, but its complexity provides multiple opportunities for preventive interventions. Mitotic inhibitors are among the strongest cancer preventive agents, not only slowing the growth rate of preneoplasias but also increasing the fidelity of DNA repair processes. Ionizing radiation, including electrons, is a strong inducer of cancer in rat skin, and dietary retinoids have shown potent cancer preventive activity in the same system. A non-toxic dietary dose of retinyl acetate altered gene expression levels 24 hours after electron irradiation of rat skin. Of the 8740 genes on an Affymetrix rat expression array, the radiation significantly (5 fold or higher) altered 188, while the retinoid altered 231, including 16 radiation-altered genes that were reversely altered. While radiation strongly affected the expression of stress response, immune/inflammation and nucleic acid metabolism genes, the retinoid most strongly affected proliferation-related genes, including some significant reversals, such as, keratin 14, retinol binding protein, and calcium binding proteins. These results point to reversal of proliferation-relevant genes as a likely basis for the anti-radiogenic effects of dietary retinyl acetate.

Review of the molecular and cellular mechanisms of action of glucocorticoids for use in asthma

Asthma is characterized by inflammation in the lung and glucocorticoids (GCs) are the most clinically effective treatment available. The success of chronic GC therapy for asthma stems largely from the ability of the GC-GC receptor (GR) complex to alter transcription of a wide array of molecules involved in the inflammatory process. Many of the adverse effects of elevated systemic GC levels have been reduced through the use of inhalation as a method of administration, as opposed to oral GC. GCs exert their effects by binding to the wild-type GR, GR(alpha). The GR(alpha) complex can directly or indirectly alter gene transcription by binding to specific DNA sites or by activating transcription factors. There is also evidence to support GR(alpha) involvement in post-translational activities. In the management of asthma, the GR(alpha) down-regulates proinflammatory mediators such as interleukin-(IL)-1, 3, and 5, and up-regulates anti-inflammatory mediators such as IkappaB [inhibitory molecule for nuclear factor kappaB1 IL-10, and 12. Newer GCs are being designed to increase potency and topical activity. Mometasone furoate (MF), has recently been developed for the treatment of asthma and inhibits key anti-inflammatory processes with a potency equal to or greater than that of fluticasone propionate. A better understanding of the molecular mechanisms involved might provide strategies for optimizing the effectiveness of GC in the treatment of asthma.

IL-6 a key cytokine in in vitro and in vivo response of Sertoli cells to external gamma irradiation

Interleukin 1(IL-1) and IL-6 are cytokines involved in the response to radiation and are known for their radioprotective properties with respect to total-body irradiation. We previously showed that after gamma irradiation of Sertoli cells (SC), we observed an increase in the activity of IL-6 but not of IL-1. The aim of this study was to see whether this response is a function of the differentiation of SC, to analyse the mechanisms responsible for this induction, and to test whether this cytokine has a radioprotective role on germ cells. Unlike IL-1, a dose-dependent increase of IL-6 activity in SC following gamma irradiation at high doses was observed at all ages studied. On the other hand, radio-induction observed at low doses (<1Gy) was dose-independent. IL-6 up-regulation resulted from transcriptional activation as shown by the use of specific inhibitors. The injection of IL-1 and IL-6 in mice prior to whole-body irradiation resulted in an increased survival rate. Moreover, cytokines protected DNA from remaining cells following irradiation as shown by comet assay on germ cells. In conclusion, IL-6 seems to constitute a good marker of exposure to gamma irradiation, both at low and high doses. In addition, we showed that IL-1 and IL-6 have a radioprotective effect at testicular level.

Fatigue, serum cytokine levels, and blood cell counts during radiotherapy of patients with breast cancer

PURPOSE

To assess the level of fatigue during the course of adjuvant radiotherapy (RT) of breast cancer patients and its relation to anxiety, depression, serum cytokines, and blood count levels.

METHODS AND MATERIALS

Forty-one patients who received adjuvant RT after breast-conserving surgery were prospectively studied. All patients underwent RT without concomitant chemotherapy. Patients rated their fatigue with two standardized self-assessment instruments, the Fatigue Assessment Questionnaire and a visual analog scale on fatigue intensity, before RT, during weeks 1-5 of RT, and 2 months after RT completion. In addition, the anxiety and depression levels were assessed with the Hospital Anxiety and Depression Scale. A differential blood cell count and the serum levels of the cytokines interleukin (IL)-1beta, IL-6, and tumor necrosis factor-alpha were determined in parallel to the fatigue assessments.

RESULTS

Fatigue intensity as assessed with the visual analog scale increased (p <0.001) until treatment week 4 and remained elevated until week 5. Two months after RT, the values had fallen to the pretreatment levels. Fatigue measured with the Fatigue Assessment Questionnaire did not increase significantly during treatment, but the subscores on physical (p = 0.035) and cognitive (p = 0.015) fatigue were elevated during treatment weeks 4 and 5. Affective fatigue did not change significantly. Anxiety, as rated with the Hospital Anxiety and Depression Scale, declined during RT (p = 0.002), but the Hospital Anxiety and Depression Scale depression score did not change significantly. IL-1beta, IL-6, and tumor necrosis factor-alpha levels did not change during therapy and did not correlate with fatigue. Peripheral blood cell levels declined significantly during therapy and were still low 2 months after treatment. Until treatment week 5, lymphocytes were reduced to almost 50% of their initial values. Hemoglobin levels did not correlate with fatigue.

CONCLUSIONS

We observed an increase in fatigue during adjuvant RT of patients with breast cancer. Fatigue returned to pretreatment levels 2 months after treatment. No evidence was found that anxiety, depression, serum levels of IL-1beta, IL-6, tumor necrosis factor-alpha, or declining hemoglobin levels were responsible for the treatment-induced fatigue.

Can short-term administration of dexamethasone abrogate radiation-induced acute cytokine gene response in lung and modify subsequent molecular responses?

PURPOSE

To investigate the effects of short-term administration of dexamethasone (DEX) on radiation-induced responses in the mouse lung, focusing on expression of pro-inflammatory cytokine and related genes.

METHODS AND MATERIALS

At indicated times after thoracic irradiation and/or drug treatment, mRNA expression levels of cytokines (mTNF-alpha, mIL-1 alpha, mIL-1 beta, mIL-2, mIL-3, mIL-4, mIL-5, mIL-6, mIFN-gamma) and related genes in the lungs of C3H/HeN mice were measured by RNase protection assay.

RESULTS

Radiation-induced pro-inflammatory cytokine mRNA expression levels in lung peak at 6 h after thoracic irradiation. DEX (5 mg/kg) suppresses both basal cytokine mRNA levels and this early response when given immediately after irradiation. However, by 24 h, in mice treated with DEX alone or DEX plus radiation, there was a strong rebound effect that lasted up to 3 days. Modification of the early radiation-induced response by DEX did not change the second wave of cytokine gene expression in the lung that occurs at 1 to 2 weeks, suggesting that early cytokine gene induction might not determine subsequent molecular events. A single dose of DEX attenuated, but did not completely suppress, increases in cytokine mRNA levels induced by lipopolysaccharide (2.5 mg/kg) treatment, but, unlike with radiation, no significant rebound effect was seen. Five days of dexamethasone treatment in the pneumonitic phase also inhibited pro-inflammatory cytokine gene expression and, again, there was a rebound effect after withdrawal of the drug.

CONCLUSIONS

Our findings suggest that short-term use of dexamethasone can temporarily suppress radiation-induced pro-inflammatory cytokine gene expression, but there may be a rebound after drug withdrawal and the drug does little to change the essence and course of the pneumonitic process.

Potent corticosteroid cream (mometasone furoate) significantly reduces acute radiation dermatitis: results from a double-blind, randomized study

PURPOSE

Radiation-induced dermatitis is a very common side effect of radiation therapy, and may necessitate interruption of the therapy. There is a substantial lack of evidence-based treatments for this condition. The aim of this study was to investigate the effect of mometasone furoate cream (MMF) on radiation dermatitis in a prospective, double-blind, randomized study.

MATERIAL AND METHODS

The study comprised 49 patients with node-negative breast cancer. They were operated on with sector resection and scheduled for postoperative radiotherapy using photons with identical radiation qualities and dosage to the breast parenchyma. The patients were randomized to receive either MMF or emollient cream. The cream was applied on the irradiated skin twice a week from the start of radiotherapy until the 12th fraction (24 Gy) and thereafter once daily until 3 weeks after completion of radiation. Both groups additionally received non-blinded emollient cream daily. The intensity of the acute radiation dermatitis was evaluated on a weekly basis regarding erythema and pigmentation, using a reflectance spectrophotometer together with visual scoring of the skin reactions.

RESULTS

MMF in combination with emollient cream treatment significantly decreased acute radiation dermatitis (P=0.0033) compared with emollient cream alone. There was no significant difference in pigmentation between the two groups.

CONCLUSIONS

Adding MMF, a potent topical corticosteroid, to an emollient cream is statistically significantly more effective than emollient cream alone in reducing acute radiation dermatitis.

The physical parameters and molecular events associated with radiation-induced lung toxicity

Radiation therapy (RT) is frequently used to treat patients with tumors in and around the thorax. Clinical radiation pneumonitis is a common side effect, occurring in 5% to 20% of patients. Efforts to identify patients at risk for pneumonitis have focused on physical factors, such as dose and volume. Recently, the underlying molecular biological mechanisms behind RT-induced lung injury have come under study. Improved knowledge of the molecular events associated with RT-induced lung injury may translate into a better ability to individualized therapy. This review discusses our current understanding of the physical and molecular factors contributing to RT-induced pulmonary injury.

Apoptosis and cytokine release induced by ionizing or ultraviolet B radiation in primary and immortalized human keratinocytes

We have compared the induction of apoptosis and cytokine release by UVB and gamma-radiation in primary (untransformed) and in two immortalized human epithelial/keratinocyte cell lines, HaCaT and KB (KB is now known to be a subline of the ubiquitous keratin-forming tumour cell line HeLa and we therefore designate it HeLa-KB). In both the primary and the immortalized cell lines apoptosis and release of the inflammatory cytokine interleukin-6 are induced rapidly following UVB irradiation. In contrast, only the immortalized cells undergo apoptosis and release interleukin-6 after gamma-irradiation and here the onset of apoptosis and cytokine release are delayed. The same distinction between primary and immortalized cells was observed when double-strand breaks were induced with the anticancer drug mitoxantrone, which stabilizes topoisomerase II-cleavable complexes. We suggest that immortalization may sensitize keratinocytes to the apoptogenic effect of ionizing radiation or mitoxantrone by deregulating normal cell cycle checkpoints. In both human keratinocytes and fibroblasts, cell killing, as assayed by loss of colony-forming ability, is not coupled to apoptosis. Immortalization increases resistance to gamma-radiation killing but sensitizes to apoptosis. In contrast, although immortalization also sensitizes to UVB-induced apoptosis, it does not affect UVB-induced cell killing. Apoptosis unambiguously indicates death at the single cell level but clonal cell survival integrates all the cellular and genetic processes which prevent or permit a scorable clone to develop.

Hemoglobin stimulates the release of proinflammatory cytokines from leukocytes in whole blood

Isolated mononuclear leukocytes, when incubated with purified hemoglobin Ao (HbAo), release the proinflammatory cytokines interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-alpha). In this study we examined whether leukocytes in whole blood, when incubated with HbAo, release IL-8, TNF-alpha, and IL-6. Leukocytes in whole blood incubated with HbAo for 4 hours at 37 degrees C, 5% CO2, and 95% humidity released 187, 1313, and 50 pg/mL of IL-6, IL-8, and TNF-alpha, respectively, as compared with 6, 192, and 2 pg/mL released by leukocytes in blood incubated with human serum albumin (HSA). Furthermore, plasma from blood incubated with HbAo exhibited chemotactic activity and stimulated human umbilical vein endothelial cells to become adherent to neutrophils. These activities were 3.3 and 2.6 times those measured in plasma from blood incubated with HSA. Hydrocortisone (0.05 micromol/L to 50 micromol/L) inhibited cytokine release in a dose-dependent manner with ED50 values of 0.23 micromol/L, 0.19 micromol/L, and 0.10 micromol/L for IL-6, IL-8, and TNF-alpha, respectively. The release of proinflammatory cytokines in whole blood after exposure to hemoglobin solutions is consistent with the possibility that an inflammatory reaction could develop on infusion of hemoglobin, whereas inhibition of cytokine release by hydrocortisone suggests that the inclusion of anti-inflammatory compounds in hemoglobin solutions may prevent undesirable effects caused by inflammation after infusion.