Antisense oligonucleotide inhibition of tumor necrosis factor receptor 1 protects the liver from radiation-induced apoptosis

Radiation-induced liver disease: beyond DNA damage

Radiation-induced liver disease (RILD), also known as radiation hepatitis, is a serious side effect of radiotherapy (RT) for hepatocellular carcinoma. The therapeutic dose of RT can damage normal liver tissue, and the toxicity that accumulates around the irradiated liver tissue is related to numerous physiological and pathological processes. RILD may restrict treatment use or eventually deteriorate into liver fibrosis. However, the research on the mechanism of radiation-induced liver injury has seen little progress compared with that on radiation injury in other tissues, and no targeted clinical pharmacological treatment for RILD exists. The DNA damage response caused by ionizing radiation plays an important role in the pathogenesis and development of RILD. Therefore, in this review, we systematically summarize the molecular and cellular mechanisms involved in RILD. Such an analysis is essential for preventing the occurrence and development of RILD and further exploring the potential treatment of this disease.

Antisense oligonucleotide is a promising intervention for liver diseases

As the body's critical metabolic organ, the liver plays an essential role in maintaining proper body homeostasis. However, as people's living standards have improved and the number of unhealthy lifestyles has increased, the liver has become overburdened. These have made liver disease one of the leading causes of death worldwide. Under the influence of adverse factors, liver disease progresses from simple steatosis to hepatitis, to liver fibrosis, and finally to cirrhosis and cancer, followed by increased mortality. Until now, there has been a lack of accepted effective treatments for liver disease. Based on current research, antisense oligonucleotide (ASO), as an alternative intervention for liver diseases, is expected to be an effective treatment due to its high efficiency, low toxicity, low dosage, strong specificity, and additional positive characteristics. In this review, we will first introduce the design, modification, delivery, and the mechanisms of ASO, and then summarize the application of ASO in liver disease treatment, including in non-alcoholic fatty liver disease (NAFLD), hepatitis, liver fibrosis, and liver cancer. Finally, we discuss challenges and perspectives on the transfer of ASO drugs into clinical use. This review provides a current and comprehensive understanding of the integrative and systematic functions of ASO for its use in liver disease.

Immunosuppressant Therapies in COVID-19: Is the TNF Axis an Alternative?

The study of cytokine storm in COVID-19 has been having different edges in accordance with the knowledge of the disease. Various cytokines have been the focus, especially to define specific treatments; however, there are no conclusive results that fully support any of the options proposed for emergency treatment. One of the cytokines that requires a more exhaustive review is the tumor necrosis factor (TNF) and its receptors (TNFRs) as increased values of soluble formats for both TNFR1 and TNFR2 have been identified. TNF is a versatile cytokine with different impacts at the cellular level depending on the action form (transmembrane or soluble) and the receptor to which it is associated. In that sense, the triggered mechanisms can be diversified. Furthermore, there is the possibility of the joint action provided by synergism between one or more cytokines with TNF, where the detonation of combined cellular processes has been suggested. This review aims to discuss some roles of TNF and its receptors in the pro-inflammatory stage of COVID-19, understand its ways of action, and let to reposition this cytokine or some of its receptors as therapeutic targets.

Radiation-induced liver injury and hepatocyte senescence

Radiation-induced liver injury (RILI) is a major complication of radiotherapy during treatment for liver cancer and other upper abdominal malignant tumors that has poor pharmacological therapeutic options. A series of pathological changes can be induced by radiation. However, the underlying mechanism of RILI remains unclear. Radiation can induce cell damage via direct energy deposition or reactive free radical generation. Cellular senescence can be observed due to the DNA damage response (DDR) caused by radiation. The senescence-associated secretory phenotype (SASP) secreted from senescent cells can cause chronic inflammation and aggravate liver dysfunction for a long time. Oxidative stress further activates the signaling pathway of the inflammatory response and affects cellular metabolism. miRNAs clearly have differential expression after radiation treatment and take part in RILI development. This review aims to systematically profile the overall mechanism of RILI and the effects of radiation on hepatocyte senescence, laying foundations for the development of new therapies.

Pre-treatment sTNFR1 and HGF levels predict toxicity and overall survival after 90Y radioembolization: potential novel application of biomarkers for personalized management of hepatotoxicity

Liver function may be negatively affected by radiation for treatment of hepatic malignancy. Pretreatment blood cytokine levels are biomarkers for prediction of toxicity and survival after external beam radiation therapy. We hypothesized that cytokines may also predict outcomes after radioembolization, enabling a biomarker-driven personalized approach to treatment. Methods: Pre-therapy blood samples from patients enrolled on a prospective protocol evaluating ⁹⁰Y radioembolization for management of intrahepatic malignancy were analyzed for two cytokines selected based on prior studies in stereotactic body radiotherapy (SBRT), soluble tumor necrosis factor receptor 1 (sTNFR1) and hepatocyte growth factor (HGF), via enzyme-linked immunosorbent assay (ELISA), and key dosimetric parameters were derived from post-treatment ⁹⁰Y PET/CT imaging. Toxicity was defined as a change in albumin-bilirubin score (ALBI) from baseline to follow up [3-6-month post-treatment (ΔALBI)]. Associations of cytokine levels, dose metrics, and baseline liver function with toxicity and overall survival were assessed. Results: Data from 43 patients treated with ⁹⁰Y radioembolization for primary [48.8% (21/43)] or secondary [51.2% (22/43)] malignancy were assessed. Examined dose metrics and baseline liver function were not associated with liver toxicity; however, levels of sTNFR1 (P = 0.045) and HGF (P = 0.005) were associated with liver toxicity in univariate models. Cytokines were the only predictors of toxicity in multivariable models including dose metrics and prior liver directed therapy. sTNFR1 (HR 12.3; CI 3.5-42.5, p<0.001) and HGF (HR 7.5; CI 2.4-23.1, p<0.001) predicted overall survival, and findings were similar when models were controlled for absorbed dose and presence of metastatic disease. Conclusion: Pretreatment cytokine levels predict liver toxicity and overall survival. These pathways can be targeted with available drugs, an advantage over previously studied dose metrics and liver function tests. Interventions directed at the TNF alpha axis should be considered in future studies for prevention of liver toxicity, and HGF should be explored further to determine whether its elevation drives toxicity or indicates ongoing liver regeneration after prior injury.

The biological effects of radiation-induced liver damage and its natural protective medicine

The biological damage caused by the environmental factors such as radiation and its control methods are one of the frontiers of life science research that has received widespread attention. Ionizing radiation can directly interact with target molecules (such as DNA, proteins and lipids) or decomposed by radiation from water, leading to changes in oxidative events and biological activities in cells. Liver is a radiation-sensitive organ, and its radiosensitivity is second only to bone marrow, lymph, gastrointestinal tissue, gonads, embryos and kidneys. In addition, as a key organ of mammals, liver performs a series of functions, including the production of bile, the metabolism of nutrients, the elimination of waste, the storage of glycogen, and the synthesis of proteins. Therefore, liver is prone to various pathophysiological changes. In this review, the effects of radiation on liver injury, its pathogenesis, bystander effect and the natural traditional Chinese medicine to protect the radiation induced liver damage are discussed.

TNFR1 and the TNFα axis as a targetable mediator of liver injury from stereotactic body radiation therapy

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Elevated soluble TNFR1 levels are predictive of liver toxicity among patients receiving radiation.

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Soluble TNFR1 levels do not independently predict liver toxicity when included in models with ALBI and mean liver dose.

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Data suggest that liver inflammation mediates toxicity after liver irradiation and that the TNFα axis is associated with this inflammation.

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Future studies of should evaluate approaches that target pre-treatment inflammation to reduce the risk of toxicity.

Introduction

Radiation therapy for the management of intrahepatic malignancies can adversely affect liver function. Liver damage has been associated with increased levels of inflammatory cytokines, including tumor necrosis factor alpha (TNFα). We hypothesized that an inflammatory state, characterized by increased soluble TNFα receptor (sTNFR1), mediates sensitivity of the liver to radiation.

Materials/Methods

Plasma samples collected during 3 trials of liver radiation for liver malignancies were assayed for sTNFR1 level via enzyme-linked immunosorbent assay (ELISA). Univariate and multivariate logistic regression and longitudinal models were used to characterize associations between liver toxicity (defined as a ≥2-point increase in Child-Pugh [CP] score within 6 months of radiation treatment) and sTNFR1 levels, ALBI score, biocorrected mean liver dose (MLD), age, and baseline laboratory values.

Results

Samples from 78 patients given liver stereotactic body radiation therapy [SBRT] (92%) or hypofractionated radiation were examined. There was a significant association between liver toxicity and sTNFR1 levels, and higher values were associated with increased toxicity over a range of mean liver doses. When ALBI score and biocorrected dose were included in the model with sTNFR1, baseline ALBI score and change in ALBI (ΔALBI) were significantly associated with toxicity, but sTNFR1 was not. Baseline aminotransferase levels also predicted toxicity but not independently of ALBI score.

Conclusions

Elevated plasma sTNFR1 levels are associated with liver injury after liver radiation, suggesting that elevated inflammatory cytokine activity is a predictor of radiation-induced liver dysfunction. Future studies should determine whether administration of agents that decrease inflammation prior to treatment is warranted.

A sparse orthogonal collimator for small animal intensity-modulated radiation therapy part I: Planning system development and commissioning

PURPOSE

To achieve more translatable preclinical research results, small animal irradiation needs to more closely simulate human radiotherapy. Although the clinical gold standard is intensity-modulated radiation therapy (IMRT), the direct translation of this method for small animals is impractical. In this study we describe the treatment planning system for a novel dose modulation device to address this challenge.

METHODS

Using delineated target and avoidance structures, a rectangular aperture optimization (RAO) problem was formulated to penalize deviations from a desired dose distribution and limit the number of selected rectangular apertures. RAO was used to create IMRT plans with highly concave targets in the mouse brain, and the plan quality was compared to that using a hypothetical miniaturized multileaf collimator (MLC). RAO plans were also created for a realistic application of mouse whole liver irradiation and for a highly complex two-dimensional (2D) dose distribution as a proof-of-principle. Beam commissioning data, including output and off-axis factors and percent depth dose (PDD) curves, were acquired for our small animal irradiation system and incorporated into the treatment planning system. A plan post-processing step was implemented for aperture size-specific dose recalculation and aperture weighting reoptimization.

RESULTS

The first RAO test case achieved highly conformal doses to concave targets in the brain, with substantially better dose gradient, conformity, and target dose homogeneity than the hypothetical miniaturized MLC plans. In the second test case, a highly conformal dose to the liver was achieved with significant sparing of the kidneys. RAO also successfully replicated a complex 2D dose distribution with three prescription dose levels. Energy spectra for field sizes 1 to 20 mm were calculated to match the measured PDD curves, with maximum and mean dose deviations of 4.47 ± 0.30% and 1.71 ± 0.18%. The final reoptimization of aperture weightings for the complex RAO test plan was able to reduce the maximum and mean dose deviations between the optimized and recalculated dose distributions from 10.3% to 6.6% and 4.0% to 2.8%, respectively.

CONCLUSIONS

Using the advanced optimization techniques, complex IMRT plans were achieved using a simple dose modulation device. Beam commissioning data were incorporated into the treatment planning process to more accurately predict the resulting dose distribution. This platform substantially reduces the gap in treatment plan quality between clinical and preclinical radiotherapy, potentially increasing the value and flexibility of small animal studies.

A translational concept of immuno-radiobiology

BACKGROUND

Traditional concepts of radiobiology model the direct radiation-induced cellular cytotoxicity but are not focused on late and sustained effects of radiation. Recent experimental data show the close involvement of immunological processes.

METHODS

Based on systematic PubMed searches, experimental data on immunological radiation effects are summarized and analyzed in a non-quantitative descriptive manner to provide a translational perspective on the immuno-modulatory impact of radiation in cancer.

RESULTS

Novel experimental findings document that sustained radiation effects are ultimately mediated through systemic factors such as cytotoxic CD8+ T cells and involve a local immuno-stimulation. Increased tumor infiltration of CD8+ T cell is a prerequisite for long-term radiation effects. CD8+ T cell depletion induces radio-resistance in experimental tumors. The proposed sequence of events involves radiation-damaged cells that release HMGB1, which activates macrophages via TLR4 to a local immuno-stimulation via TNF, which contributes to maturation of DCs. The mature DCs migrate to lymph nodes where they trigger effective CD8+ T cell responses. Radiation effects are boosted, when the physiological self-terminating negative feedback of immune reactions is antagonised via blocking of TGF-β or via checkpoint inhibition with involvement of CD8+ T cells as common denominator.

CONCLUSION

The concept of immuno-radiobiology emphasizes the necessity for a functional integrity of APCs and T cells for the long-term effects of radiotherapy. Local irradiation at higher doses induces tumor infiltration of CD8+ T cells, which can be boosted by immunotherapy. More systematic research is warranted to better understand the immunological effects of escalating radiation doses.

Serum Levels of Hepatocyte Growth Factor and CD40 Ligand Predict Radiation-Induced Liver Injury

BACKGROUND: Declining liver function is a concerning side effect associated with radiation therapy. Biomarkers of liver toxicity would be useful in personalizing therapy. METHODS: As part of two prospective clinical trials examining adaptive radiation therapy, we collected serum samples from patients receiving liver radiation. We performed a screen of 22 cytokines using a multiplex assay then used ELISA to quantify the cytokines of greatest interest. Subjects were split into screening and validation cohorts. Toxicity was defined as an increase in Child-Pugh score of 2 points or greater within 6 months. Logistic regression models were used to estimate the relationship between our toxicity endpoint and serum cytokine concentrations. RESULTS: Our initial screen (46 subjects, 11 events) identified hepatocyte growth factor (HGF), CD40L (CD154), and eotaxin (CCL11) as potentially predictive of toxicity. We then tested these markers in an expanded patient cohort (104 subjects, 18 events) with a batch correction due to varying age of the samples which confirmed that high HGF and low CD40L were associated with a subsequent decline in liver function following radiation therapy. Multivariate analysis factoring in baseline Child-Pugh score and mean liver radiation dose demonstrated that HGF and CD40L were potentially predictive of toxicity (HGF OR 4.3, P = .009; CD40L OR 0.5 P = .06). Additionally, higher than median baseline HGF levels (1.4 ng/ml) were significantly associated with decreased survival following liver radiation (27.1 vs 14.5 months, P = .03). CONCLUSIONS: Our study identifies high HGF and low CD40L as potential markers of liver toxicity following radiation therapy.

Transient Inhibition of mTORC1 Signaling Ameliorates Irradiation-Induced Liver Damage

Recurrent liver cancer after surgery is often treated with radiotherapy, which induces liver damage. It has been documented that activation of the TGF-β and NF-κB signaling pathways plays important roles in irradiation-induced liver pathologies. However, the significance of mTOR signaling remains undefined after irradiation exposure. In the present study, we investigated the effects of inhibiting mTORC1 signaling on irradiated livers. Male C57BL/6J mice were acutely exposed to 8.0 Gy of X-ray total body irradiation and subsequently treated with rapamycin. The effects of rapamycin treatment on irradiated livers were examined at days 1, 3, and 7 after exposure. The results showed that 8.0 Gy of irradiation resulted in hepatocyte edema, hemorrhage, and sinusoidal congestion along with a decrease of ALB expression. Exposure of mice to irradiation significantly activated the mTORC1 signaling pathway determined by pS6 and p-mTOR expression via western blot and immunostaining. Transient inhibition of mTORC1 signaling by rapamycin treatment consistently accelerated liver recovery from irradiation, which was evidenced by decreasing sinusoidal congestion and increasing ALB expression after irradiation. The protective role of rapamycin on irradiated livers might be mediated by decreasing cellular apoptosis and increasing autophagy. These data suggest that transient inhibition of mTORC1 signaling by rapamycin protects livers against irradiation-induced damage.

Clitoria ternatea flower petals: Effect on TNFR1 neutralization via downregulation of synovial matrix metalloproteases

ETHNOPHARMACOLOGICAL RELEVANCE

Clitoria ternatea Linn. (C. ternatea) is a traditionally used herb in arthritis, and its anti-arthritic activity has been attributed to polyphenols (e.g. quercetins) from its flower petal.

AIM OF THE STUDY

The present study was designed to investigate whether C. ternatea or quercetin-3ß-D-glucoside (QG) support the antibody mediated TNFα-receptor 1 (TNFR1) neutralization to ameliorate arthritis in mice.

MATERIALS AND METHODS

Development of collagen-induced arthritis (CIA) in male Swiss mice (20-22g, 3-4 weeks of age) was followed by estimation of synovial polymorphonuclear cell (PMN) accumulation (in terms of myeloperoxidase activity), synovial and systemic release of cytokines, chemokines and C-reactive protein (CRP) by enzyme-linked immunosorbent assay (ELISA), biochemical estimation of synovial free radical generation and antioxidant status, as well as immunoblot assessment of synovial TNFR1, toll-like receptor 2(TLR2), cyclooxygenase-2(COX-2) and inducible nitric oxide synthase (iNOS) expression; and zymographic analysis of synovial matrix-metalloprotease-2 (MMP-2) activity.

RESULTS

CIA was induced from day 2 post-secondary immunizations as evidenced from arthritic scores and joint swelling in parallel to increased inflammatory and oxidative stress parameters in synovial joints. Long term supplementation with extract from Clitoria ternatea flower petals CTE (50mg/kg) and QG (2.5mg/kg) upto 24 days post booster immunization augmented anti-arthritic potential of TNFR1 neutralization with anti-TNFR1 antibody (10μg per mice) in terms of reduced MPO activity, decrease in release of pro-inflammatory cytokines, chemokines, reactive oxygen species (ROS)/ reactive nitrogen species (RNS) production in parallel to significant (p<0.05) reduction in TNFR1, TLR2, iNOS, COX-2 and MMP-2 expression.

CONCLUSION

CTE and QG possess potential anti-arthritic activity which targets synovial MMP-2 in arthritic joints and TNFR1 targeting followed by CTE or QG treatment might become a combinatorial approach in future therapeutic research in treatment of arthritis.

放射性肝损伤的研究进展

我国是肝癌大国, 肝癌的年发病及死亡人数均占全球一半以上. 很多患者在肝癌发展的不同时期会接受放射治疗. 放射性肝损伤(radiation-induced liver damage, RILD)是由放射治疗导致的一种临床亚急性、慢性肝脏损伤, 是胸部和上腹部肿瘤放疗及骨髓移植前预处理中最严重的并发症之一. RILD极大地影响了胸腹部肿瘤, 特别是肝癌的放疗疗效. 因此, 本综述对RILD的病理、影像学特点、临床评估及防治作一归纳总结.

Pulmonary injury associated with radiation therapy - Assessment, complications and therapeutic targets

Pulmonary injury is more common in patients undergoing radiation therapy for lungs and other thoracic malignancies. Recently with the use of most-advanced technologies powerful doses of radiation can be delivered directly to tumor site with exquisite precision. The awareness of technical and clinical parameters that influence the chance of radiation induced lung injury is important to guide patient selection and toxicity minimization strategies. At the cellular level, radiation activates free radical production, leading to DNA damage, apoptosis, cell cycle changes, and reduced cell survival. Preclinical research shows the potential for therapies targeting transforming growth factor-β (TGF-B), Toll like receptor (TLRs), Tumour necrosis factor-alpha (TNF-alpha), Interferon gamma (IFN-γ) and so on that may restore lung function. At present Amifostine (WR-2721) is the only approved broad spectrum radioprotector in use for patients undergoing radiation therapy. Newer techniques also offer the opportunity to identify new biomarkers and new targets for interventions to prevent or ameliorate these late effects of lung damage.

Radioprotective effect of kupffer cell depletion on hepatic sinusoidal endothelial cells

Radiation-induced liver injury remains a clinical problem and data suggest that sinusoidal endothelial cells (SECs) are an important target. The purpose of this study was to determine whether the inhibition of Kupffer cells before exposure would protect SECs from radiation-induced injury. Sprague-Dawley rats were intravenously injected 24 h before irradiation with Kupffer cell inhibitor gadolinium chloride (GdCl3) (10 mg/kg body weight). Three groups of animals were treated: 1. control group (saline and sham irradiation); 2. GdCl3 + 30 Gy radiation group and 3. 30 Gy radiation only group. Specimens were collected at 2, 6, 12, 24 and 48 h after completion of each treatment. Liver tissue was assessed for inflammatory cytokine expression and radiation-induced SEC injury based on serum hyaluronic acid (HA) level, apoptosis and ultrastructural and histological analyses. The results showed that radiation exposure caused apoptosis of SECs, but not hepatocytes. Inflammatory cytokine expression, including tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) expression, was significantly attenuated in the GdCl3 + 30 Gy radiation group, compared with the 30 Gy radiation-only group (P < 0.05). The GdCl3 + radiation-treated rats exhibited significantly lower levels of HA and SEC apoptosis than the radiation-treated only rats at early time points, and radiation-induced liver injury was also attenuated. In conclusion, we hypothesize that selective Kupffer cell inhibition by gadolinium chloride was shown to reduce apoptosis in SECs caused by irradiation of the live and protected the liver against radiation-induced injury.

Regulation and dysregulation of tumor necrosis factor receptor-1

TNF is an essential regulator of the immune system. Dysregulation of TNF plays a role in the pathology of many auto-immune diseases. TNF-blocking agents have proven successful in the treatment of such diseases. Development of novel, safer or more effective drugs requires a deeper understanding of the regulation of the pro-inflammatory activities of TNF and its receptors. The ubiquitously expressed TNFR1 is responsible for most TNF effects, while TNFR2 has a limited expression pattern and performs immune-regulatory functions. Despite extensive knowledge of TNFR1 signaling, the regulation of TNFR1 expression, its modifications, localization and processing are less clear and the data are scattered. Here we review the current knowledge of TNFR1 regulation and discuss the impact this has on the host.

Differential effects of cyclosporin and etanercept treatment on various pathologic parameters in a murine model of irradiation-induced mucositis

BACKGROUND

Radiation therapy is the most prescribed treatment for many oncologic indications. One of its common side effects is mucositis with hallmark apoptosis in the intestinal crypt and diarrhea.

OBJECTIVE

We investigated the potential beneficial effects of etanercept and cyclosporin treatment during radiation exposure. The effects of these drugs on intestinal apoptosis, long-term weight loss, diarrhea severity, and survival were examined.

METHODS

For acute observation studies, animals pretreated with phosphate buffer saline (PBS) vehicle, either etanercept, or cyclosporin were challenged with either 1 Gy or 13 Gy irradiation and sacrificed 6 hours later. The animals' small intestines were then harvested for histologic analysis. For chronic survival studies, 14.5 Gy irradiation was applied. Etanercept or cyclosporin treatments were given 15 minutes before the irradiation, followed by daily administration.

RESULTS

At 6 hours postirradiation the maximum apoptotic index observed in the small intestine was ∼25% for both 1 Gy and 13 Gy irradiation. Etanercept and cyclosporin pretreatment had no effect on the irradiation-induced apoptosis. During chronic observation, the rate of weight loss was similar in all test groups. At 7 days postirradiation, the weight loss in phosphate buffered saline-treated control, etanercept, and cyclosporin groups reached a maximum at 19%, 24%, and 31.8%, respectively. The weight lost in the cyclosporin group was significantly higher than in the control group. Neither treatment reduced the severity of diarrhea, but cyclosporin increased the survival rate. Sixty percent of cyclosporin-treated animals survived compared with 27% in the PBS-treated control group and 47% in the etanercept-treated group. Serum tumor necrosis factor-α levels, a biomarker for both etanercept's mechanism of action and treatment efficacy, was inhibited by etanercept throughout the study, but cyclosporin only showed an inhibitory effect at 48 hours postirradiation.

CONCLUSIONS

Our study demonstrates that cyclosporin increases the survival rate of irradiated animals without affecting parameters such as intestinal histology, weight loss, and diarrhea severity.

Antisense oligonucleotides against TNFR1 prevent toxicity of TNF/IFNγ treatment in mouse tumor models

Tumor necrosis factor (TNF) has remarkable antitumor effects, but its systemic therapeutic use is prevented by its lethal inflammatory effects. TNFR1 (P55) is essential for both the antitumor and toxic effects because both of them are absent in P55-deficient mice. In previous work we demonstrated that P55+/- mice are completely resistant to TNF toxicity, while the antitumor effects induced by TNF combined with interferon gamma (IFNγ) remain fully functional in these mice. Hence, a high dose of TNF/IFNγ has an excellent therapeutic potential when P55 levels are reduced, because TNF induces tumor regression without systemic toxicity. Here, we provide proof of principle for therapeutic application of this approach by using antisense oligonucleotides (ASOs). Treatment of mice with ASOs targeting P55 resulted in a strong reduction in P55 protein levels in liver, small intestine and blood mononuclear cells. This P55 downregulation was associated with significant protection of mice against acute TNF toxicity as measured by hypothermia, systemic inflammation and lethality. This treatment also protected mice against toxicity of TNF/IFNγ treatment in several cancer models: B16Bl6, Lewis lung carcinoma and a lung colony model. Our results confirm the therapeutic value of this strategy, which could lead to the development of a safer and more effective TNF/IFNγ antitumor therapy.

Programmed cell death in a patient with hepatocellular carcinoma treated with yttrium-90 and doxorubicin-loaded beads

Molecular analysis of apoptosis and autophagy pathways was performed from a single hepatocellular carcinoma treated with yttrium-90 and doxorubicin-loaded beads before resection and compared with normal liver tissue from the margins. Both bead formulations activated apoptosis-associated mechanisms and increased autophagy pathway protein levels. Increased DNA fragmentation and autophagy markers were seen in tumor treated with drug-eluting beads compared with yttrium-90-treated tumor. These results suggest that both microembolic therapies activate cell death signaling, although differences in apoptosis and autophagy pathways were seen in this patient. Knowledge of mechanisms of action for each treatment may enhance future therapeutic strategies.

Antagonistic TNF receptor one-specific antibody (ATROSAB): receptor binding and in vitro bioactivity

Background

Selective inhibition of TNFR1 signaling holds the potential to greatly reduce the pro-inflammatory activity of TNF, while leaving TNFR2 untouched, thus allowing for cell survival and tissue homeostasis. ATROSAB is a humanized antagonistic anti-TNFR1 antibody developed for the treatment of inflammatory diseases.

Methodology/Principal Findings

The epitope of ATROSAB resides in the N-terminal region of TNFR1 covering parts of CRD1 and CRD2. By site-directed mutagenesis, we identified Arg68 and His69 of TNFR1 as important residues for ATROSAB binding. ATROSAB inhibited binding of ¹²⁵I-labeled TNF to HT1080 in the subnanomolar range. Furthermore, ATROSAB inhibited release of IL-6 and IL-8 from HeLa and HT1080 cells, respectively, induced by TNF or lymphotoxin alpha (LTα). Different from an agonistic antibody (Htr-9), which binds to a region close to the ATROSAB epitope but elicits strong TNFR1 activation, ATROSAB showed a negligible induction of IL-6 and IL-8 production over a broad concentration range. We further verified that ATROSAB, comprising mutations within the Fc region known to abrogate complement fixation and antibody-mediated cellular effector functions, indeed lacks binding activity for C1q, FcγRI (CD64), FcγRIIB (CD32b), and FcγRIII (CD16) disabling ADCC and CDC.

Conlusions/Significance

The data corroborate ATROSAB’s unique function as a TNFR1-selective antagonist efficiently blocking both TNF and LTα action. In agreement with recent studies of TNFR1 complex formation and activation, we suggest a model of the underlying mechanism of TNFR1 inhibition by ATROSAB.

Stimulation of hepatoma cell invasiveness and metastatic potential by proteins secreted from irradiated nonparenchymal cells

PURPOSE

To determine whether factors secreted by irradiated liver nonparenchymal cells (NPCs) may influence invasiveness and/or metastatic potential of hepatocellular carcinoma (HCC) cells and to elucidate a possible mechanism for such effect.

METHODS AND MATERIALS

Primary rat NPCs were cultured and divided into irradiated (10-Gy X-ray) and nonirradiated groups. Forty-eight hours after irradiation, conditioned medium from irradiated (SR) or nonirradiated (SnonR) cultures were collected and added to sublethally irradiated cultures of the hepatoma McA-RH7777 cell line. Then, hepatoma cells were continuously passaged for eight generations (RH10Gy-SR and RH10Gy-SnonR). The invasiveness and metastatic potential of McA-RH7777, RH10Gy-SnonR, and RH10Gy-SR cells were evaluated using an in vitro gelatinous protein (Matrigel) invasion and an in vivo metastasis assay. In addition, SR and SnonR were tested using rat cytokine antibody arrays and enzyme-linked immunosorbent assay (ELISA).

RESULTS

In vitro gelatinous protein invasion assay indicated that the numbers of invading cells was significantly higher in RH10Gy-SR (40 ± 4.74) than in RH10Gy-SnonR (30.6 ± 3.85) cells, and lowest in McA-RH7777 (11.4 ± 3.56) cells. The same pattern was observed in vivo in a lung metastasis assay, as evaluated by number of metastatic lung nodules seen with RH10Gy-SR (28.83 ± 5.38), RH10Gy-SnonR (22.17 ± 4.26), and McA-RH7777 (8.3 ± 3.8) cells. Rat cytokine antibody arrays and ELISA demonstrated that metastasis-promoting cytokines (tumor necrosis factor-α and interleukin-6), circulating growth factors (vascular endothelial growth factor and epidermal growth factor), and metalloproteinases (MMP-2 and MMP-9) were upregulated in SR compared with SnonR.

CONCLUSIONS

Radiation can increase invasiveness and metastatic potential of sublethally irradiated hepatoma cells, and soluble mediators released from irradiated NPCs promote this potential. Increased secretion of metastasis-related cytokines and factors from NPCs after irradiation may be a possible mechanism for the radiation-induced invasiveness and metastatic potential of HCC.

In vivo effects of immunomodulators in a murine model of Fluorouracil-induced mucositis

BACKGROUND

Fluorouracil (5-FU) is a pyrimidine analogue used as a cancer treatment. Its toxic side effects, including mucositis, are reported to occur in 40% of the treated patients. Because of the inflammatory component of mucositis, we explored the possibility of modulating this condition with an immunomodulatory agent and a tumor necrosis factor-α inhibitor.

OBJECTIVE

The aim of this study was to evaluate the effect of 2 immunosuppressive agents, etanercept and cyclosporine, in a murine model of 5-FU-induced mucositis.

METHODS

To study the short-term effects of 5-FU on mucositis, cyclosporine and etanercept were administered to mice after an injection of 5-FU. The animals (n = 8) were euthanized at 6 hours post-challenge. Hematoxylin and eosin-stained histologic sections of the small intestine were examined for signs of apoptosis. To further examine the potential of cyclosporine in the treatment of 5-FU-induced mucositis in a longer duration, the animals (N = 15) were given 2 challenges of 5-FU within 6 hours. All mice were dosed daily until day 9 with either cyclosporine (100 mg/kg) or phosphate-buffered saline (PBS).

RESULTS

Six hours after 5-FU challenge, 25 mg/kg etanercept and 50 mg/kg cyclosporine had no effect on 5-FU-induced apoptosis (P > 0.05). However, 100 mg/kg cyclosporine significantly reduced the cumulative level of apoptosis >41.6% of the intestinal crypt surface (P < 0.05). During long-term observation, all mice began to lose weight at a rate of approximately 0.8 g/day after 5-FU exposure. The rates of weight loss and survival were not affected by cyclosporine treatment. The diarrhea onset began on day 4 with 46.7% of the PBS-treated mice showing signs of diarrhea compared with 53.3% in the cyclosporine group. The diarrhea score for both groups plateaued on day 7, with a cumulative score of 41 for the PBS group and 50 for the cyclosporine group. Cyclosporine treatment did not affect the diarrhea onset day or severity compared with the PBS-treated group (P > 0.05).

CONCLUSIONS

Our data indicated that etanercept is not a suitable treatment for 5-FU-induced mucositis. Despite decreased apoptosis in the gut, cyclosporine did not affect the severity of the diarrhea or survival. Therefore, we concluded that cyclosporine treatment was only effective in mediating the short-term apoptotic events in the intestines but has no long-term effect on the animals' survival and diarrhea.

Treatment of TNF mediated diseases by selective inhibition of soluble TNF or TNFR1

The TNF signaling pathway is a valuable target in the therapy of autoimmune diseases, and anti-TNF drugs are successfully used to treat diseases such as rheumatoid arthritis, Crohn's disease and psoriasis. By their ability to interfere with inflammatory processes at multiple levels, these TNF blockers have become invaluable tools to inhibit the inflammation induced damage and allow recovery of the affected tissues. Unfortunately this therapy has some drawbacks, including increased risk of infection and malignancy, and remarkably, the onset of new auto-immune diseases. Some of these effects are caused by the unwanted abrogation of beneficial TNF signaling. More specific targeting of the pathological TNF-induced signaling might lead to broader applicability and improved safety. Specificity might be increased by inhibiting the soluble TNF/TNFR1 axis while leaving the often beneficial transmembrane TNF/TNFR2 signaling untouched. This approach looks promising because it inhibits the pathological effects of TNF and reduces the side effects, and it opens the way for the treatment of other diseases in which TNFR2 inhibition is detrimental. In this review we give an overview of in vivo mouse studies of TNF mediated pathologies demonstrating that the blockade or genetic deletion of sTNF or TNFR1 is preferable over total TNF blockade.

Potential targets for intervention in radiation-induced heart disease

Radiotherapy of thoracic and chest wall tumors, if all or part of the heart was included in the radiation field, can lead to radiation-induced heart disease (RIHD), a late and potentially severe side effect. RIHD presents clinically several years after irradiation and manifestations include accelerated atherosclerosis, pericardial and myocardial fibrosis, conduction abnormalities, and injury to cardiac valves. The pathogenesis of RIHD is largely unknown, and a treatment is not available. Hence, ongoing pre-clinical studies aim to elucidate molecular and cellular mechanisms of RIHD. Here, an overview of recent pre-clinical studies is given, and based on the results of these studies, potential targets for intervention in RIHD are discussed.

Administration of granulocyte colony-stimulating factor ameliorates radiation-induced hepatic fibrosis in mice

On the basis of the recent report that granulocyte colony-stimulating factor (G-CSF) treatment significantly improves survival and liver histology among chemically injured mice, we investigated whether G-CSF administration could contribute to faster recovery and promote tissue repair after local liver irradiation. Bone marrow chimeric female C57BL/6 mice were treated with G-CSF at days 7, 14, and 21 after local liver irradiation. We assessed the fibrosis index and the origin of proliferating cells reconstituting the liver at 2 or 5 weeks after radiation challenge. At day 35 after local irradiation, we observed G-CSF treatment to significantly reduce radiation-induced liver damage and collagen deposition. In addition, hepatic hydroxyproline levels and serum fibrosis markers in mice receiving G-CSF administration after radiation challenge were significantly lower compared with those of control mice. More importantly, histological examination suggested that recovery from hepatic damage was much better among the G-CSF-treated mice. Immunofluorescence and fluorescence in situ hybridization analyses revealed that donor cells engrafted into the host liver displayed epithelium-like morphology and expressed albumin, albeit at low frequency. These results suggested that G-CSF treatment initiated endogenous hepatic tissue regeneration in response to radiation injury and ameliorated its fibrogenic effects.

14-Deoxyandrographolide desensitizes hepatocytes to tumour necrosis factor-alpha-induced apoptosis through calcium-dependent tumour necrosis factor receptor superfamily member 1A release via the NO/cGMP pathway

BACKGROUND AND PURPOSE

Andrographis paniculata (AP) has been found to display hepatoprotective effect, although the mechanism of action of the active compounds of AP in this context still remains unclear. Here, we evaluated the hepatoprotective efficacy of 14-deoxyandrographolide (14-DAG), a bioactive compound of AP, particularly its role in desensitization of hepatocytes to tumour necrosis factor-alpha (TNF-alpha)-induced signalling of apoptosis.

EXPERIMENTAL APPROACH

TNF-alpha-mediated ligand receptor interaction in hepatocytes in the presence of 14-DAG was studied in vitro in primary hepatocyte cultures, with the help of co-immunoprecipitation, confocal microscopy and FACS analysis. Events associated with 14-DAG-induced TNFRSF1A release from hepatocytes were determined using immunoblotting, biochemical assay and fluorimetric studies. Pulse-chase experiments with radiolabelled TNF-alpha and detection of apoptotic nuclei by terminal transferase-mediated dUTP nick-end labelling were performed under in vivo conditions.

KEY RESULTS

14-DAG down-regulated the formation of death-inducing signalling complex, resulting in desensitization of hepatocytes to TNF-alpha-induced apoptosis. Pretreatment of hepatocytes with 14-DAG accentuated microsomal Ca-ATPase activity through induction of NO/cGMP pathway. This resulted in enhanced calcium influx into microsomal lumen with the formation of TNFRSF1A-ARTS-1-NUCB2 complex in cellular vesicles. It was followed by the release of full-length 55 kDa TNFRSF1A and a reduction in the number of cell surface TNFRSF1A, which eventually caused diminution of TNF-alpha signal in hepatocytes.

CONCLUSION AND IMPLICATION

Taken together, the results demonstrate for the first time that 14-DAG desensitizes hepatocytes to TNF-alpha-mediated apoptosis through the release of TNFRSF1A. This can be used as a strategy against cytokine-mediated hepatocyte apoptosis in liver dysfunctions.

Preclinical research into basic mechanisms of radiation-induced heart disease

Radiation-induced heart disease (RIHD) is a potentially severe side effect of radiotherapy of thoracic and chest wall tumors if all or part of the heart was included in the radiation field. RIHD presents clinically several years after irradiation and manifestations include accelerated atherosclerosis, pericardial and myocardial fibrosis, conduction abnormalities, and injury to cardiac valves. There is no method to prevent or reverse these injuries when the heart is exposed to ionizing radiation. This paper presents an overview of recent studies that address the role of microvascular injury, endothelial dysfunction, mast cells, and the renin angiotensin system in animal models of cardiac radiation injury. These insights into the basic mechanisms of RIHD may lead to the identification of targets for intervention in this late radiotherapy side effect.

Links between innate immunity and normal tissue radiobiology

The body senses "danger" from "damaged self" molecules through members of the same receptor superfamily it uses for microbial "non-self", triggering canonical signaling pathways that lead to the generation of acute inflammatory responses. For this reason, the biology of normal tissue responses to moderate and clinically relevant doses of radiation is inextricably connected to innate immunity. The complex sequence of inflammatory events that ensues causes further cell and tissue damage to eliminate potential invaders but also leads to cytoprotective responses that limit the spread of damage and to wound healing through tissue regeneration or replacement. These sequential processes are orchestrated through multiple feedback control mechanisms involving cyclical production of free radicals and cytokines that are common to both radiation and immune signaling. This requires a concerted effort by resident tissue and inflammatory cell types, with macrophages apparently leading the way. The initial response to moderate doses of radiation therefore feeds into a pro-inflammatory paradigm whose eventual outcome is critically dependent upon the properties of the immune cells that are involved in tissue damage, regeneration and repair and that are in part under genetic influence. Importantly, these canonical pathways provide targets for interventions aimed at modifying normal tissue radiation responses. In this review, we examine areas of intersection between innate immunity and normal tissue radiobiology.

Inactivation of kupffer cells by gadolinium chloride protects murine liver from radiation-induced apoptosis

PURPOSE

To determine whether the inhibition of Kupffer cells before radiotherapy (RT) would protect hepatocytes from radiation-induced apoptosis.

MATERIALS AND METHODS

A single 30-Gy fraction was administered to the upper abdomen of Sprague-Dawley rats. The Kupffer cell inhibitor gadolinium chloride (GdCl3; 10 mg/kg body weight) was intravenously injected 24 h before RT. The rats were divided into four groups: group 1, sham RT plus saline (control group); group 2, sham RT plus GdCl3; group 3, RT plus saline; and group 4, RT plus GdCl3. Liver tissue was collected for measurement of apoptotic cytokine expression and evaluation of radiation-induced liver toxicity by analysis of liver enzyme activities, hepatocyte micronucleus formation, apoptosis, and histologic staining.

RESULTS

The expression of interleukin-1beta, interleukin-6, and tumor necrosis factor-alpha was significantly attenuated in group 4 compared with group 3 at 2, 6, 24, and 48 h after injection (p <0.05). At early points after RT, the rats in group 4 exhibited significantly lower levels of liver enzyme activity, apoptotic response, and hepatocyte micronucleus formation compared with those in group 3.

CONCLUSION

Selective inactivation of Kupffer cells with GdCl3 reduced radiation-induced cytokine production and protected the liver against acute radiation-induced damage.

Regenerative capacity of normal and irradiated liver following partial hepatectomy in rats

PURPOSE

To investigate the regenerative capacity and proliferation related to cell cycle modulators in irradiated livers after partial hepatectomy (PH) in rats.

METHODS AND MATERIALS

Two experimental groups were given a single dose of either 4-Gy or 8-Gy photon radiation to the whole liver following PH. The control group underwent only PH, without irradiation. The liver specimens were analysed for apoptosis, proliferation and cell cycle related genes between 0.5 and 12 days.

RESULTS

Mean change in weight of the remnant liver in the 8-Gy group was significantly lower than in the control and 4-Gy groups. The apex of proliferating cell nuclear antigen labelling and bromodeoxyuridine incorporation index in two irradiated groups were also apparently lower than that in control group. After PH, transforming growth factor beta-1 (TGFbeta1), and the type II receptor of TGFbeta (TGFbetaR-II), anti-tumour protein 53(p53) and anti-tumour protein21(p21) protein expression in the irradiated livers was higher than in unirradiated ones. Significant apoptosis was noted in 8-Gy group. However, the maximal value of hepatocyte growth factor (HGF) mRNA and protein expression in the irradiated group was suppressed and restoration of liver function was delayed.

CONCLUSION

Whole liver lower dose irradiation can attenuate regenerative capacity following partial hepatectomy in rats.

Effect of tumour necrosis factor-alpha and irradiation alone or in combination on the viability of hepatocellular and biliary adenocarcinoma cell lines in vitro

BACKGROUND

Tumour necrosis factor alpha (TNF-alpha) may exhibit antitumoral activity and can influence the reaction of both tumour and normal tissue to radiation.

AIMS

To test the effect of TNF-alpha and/or irradiation on hepatocellular (HepG2, Hep3B, Sk-Hep1, HuH7) and cholangiocellular (Sk-chA1, Mz-chA1) tumour cell lines.

METHODS

Colony formation, apoptosis analysis and trypan blue exclusion were used to assess cell viability. Doses of radiation (2-25 Gy) and TNF-alpha (100-50,000 U) as well as their respective sequencing were varied (24 and 12 h before and 6 h after). The expression of TNF-alpha and TNF receptors 1/2 was determined using real-time polymerase chain reaction and IkappaBalpha protein expression was detected by Western blot.

RESULTS

Sole irradiation induced a reduction in colony formation in all cell lines and sole TNF-alpha in HepG2 and Sk-chA1 cells only. No difference in apoptosis induction after TNF-alpha or irradiation was observed. Cellular death induced by the combination of TNF-alpha and radiation was not superior to the use of any of the two agents alone. All cell lines revealed that radiation induced upregulation of TNF-alpha whereas the extent of TNF receptor-specific transcription did not change. Furthermore, radiation-induced changes in IkappaBalpha expression were not detectable.

CONCLUSIONS

Our data suggest that both TNF-alpha and radiation may be treatment options for hepatocellular and cholangiocellular carcinomas. Because TNF-alpha and radiation do not interact in terms of radiosensitization, anti-TNF-alpha treatment may have the potential to protect against hepatocellular injury after abdominal irradiation. However, further in vivo studies are needed to confirm that anti-TNF-alpha treatment does not compromise tumour control and actually attenuates radiation-induced liver injury.

Irradiation leads to sensitization of hepatocytes to TNF-alpha-mediated apoptosis by upregulation of IkappaB expression

This study aimed to reveal the pathophysiological signalling responsible for radiation-induced sensitization of hepatocytes to TNF-alpha-mediated apoptosis. IkappaB was upregulated in irradiated hepatocytes. Administration of IkappaB antisense oligonucleotides prior to irradiation inhibited occurrence of apoptosis after TNF-alpha administration. Caspases-8, -9 and -3 activities were increased in irradiated hepatocytes and downregulation of apoptosis by IkappaB antisense oligonucleotides was mediated by suppression of caspases-9 and -3 activation but not of caspase-8 activation, suggesting that radiation-induced sensitization of hepatocytes to TNF-alpha-mediated apoptosis additionally requires changes upstream of caspase-8 activation. Herein, upregulation of FLIP may play a crucial role. Cleavage of bid, upregulation of bax, downregulation of bcl-2 and release of cytochrome c after TNF-alpha-administration depend on radiation-induced upregulation of IkappaB, thus demonstrating an apoptosis permitting effect of IkappaB.

Inhibition of the tumor necrosis factor-alpha pathway is radioprotective for the lung

PURPOSE

Radiation-induced lung toxicity limits the delivery of high-dose radiation to thoracic tumors. Here, we investigated the potential of inhibiting the tumor necrosis factor-alpha (TNF-alpha) pathway as a novel radioprotection strategy.

EXPERIMENTAL DESIGN

Mouse lungs were irradiated with various doses and assessed at varying times for TNF-alpha production. Lung toxicity was measured by apoptosis and pulmonary function testing. TNF receptor 1 (TNFR1) inhibition, achieved by genetic knockout or antisense oligonucleotide (ASO) silencing, was tested for selective lung protection in a mouse lung metastasis model of colon cancer.

RESULTS

Lung radiation induced local production of TNF-alpha by macrophages in BALB/c mice 3 to 24 hours after radiation (15 Gy). A similar maximal induction was found 1 week after the start of radiation when 15 Gy was divided into five daily fractions. Cell apoptosis in the lung, measured by terminal deoxyribonucleotide transferase-mediated nick-end labeling staining (mostly epithelial cells) and Western blot for caspase-3, was induced by radiation in a dose- and time-dependent manner. Specific ASO inhibited lung TNFR1 expression and reduced radiation-induced apoptosis. Radiation decreased lung function in BALB/c and C57BL mice 4 to 8 weeks after completion of fractionated radiation (40 Gy). Inhibition of TNFR1 by genetic deficiency (C57BL mice) or therapeutic silencing with ASO (BALB/c mice) tended to preserve lung function without compromising lung tumor sensitivity to radiation.

CONCLUSION

Radiation-induced lung TNF-alpha production correlates with early cell apoptosis and latent lung function damage. Inhibition of lung TNFR1 is selectively radioprotective for the lung without compromising tumor response. These findings support the development of a novel radioprotection strategy using inhibition of the TNF-alpha pathway.

Comparative proteomic analysis of radiation-induced changes in mouse lung: fibrosis-sensitive and -resistant strains

To determine whether comparative proteomics could detect differential protein expression after lung irradiation in two mouse strains with different radiation responses, lung proteins were subjected to two-dimensional orthogonal liquid-phase separations, with chromatofocusing in the first dimension and nonporous silica reverse-phase high-performance liquid chromatography (NPS-RP-HPLC) in the second. Five weeks after 12 Gy whole-lung irradiation, 15 and 31 proteins had significantly altered expression levels in C3H/HeJ (less likely to develop lung fibrosis) and C57BL/6J mice (more likely to develop lung fibrosis), respectively. These proteins were analyzed by HPLC-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) and identified by matching sequences in a peptide database. The proteins are associated with redox, energy consumption, glycolysis, or chromatin/ RNA structure formation. Five of the six redox-related proteins, including superoxide dismutase 1 (SOD1), cytochrome c oxidase, glutamate dehydrogenase, biliverdin reductase, peroxiredoxin and carbonyl reductase, were down-regulated in the irradiated C57BL/6J mice, whereas SOD1, sulfurtransferase and carbonyl reductase increased in the irradiated C3H/ HeJ mice. Thus decreased antioxidant proteins in the irradiated C57BL/6J mice may be correlated with increased early lung toxicity. Changes in SOD1 and 8-hydroxydeoxy-guanosine (8-OHdG, an oxidative stress marker) were further confirmed by immunohistochemistry and/or Western blot analysis. These data suggest that a proteomics approach has the potential to detect protein changes relevant to early lung toxicity after irradiation.