Prevention of radiation-induced pneumonitis by recombinant adenovirus-mediated transferring of soluble TGF-β type II receptor gene

Cytokine, chemokine alterations and immune cell infiltration in Radiation-induced lung injury: Implications for prevention and management

Radiation therapy is one of the primary treatments for thoracic malignancies, with radiation-induced lung injury (RILI) emerging as its most prevalent complication. RILI encompasses early-stage radiation pneumonitis (RP) and the subsequent development of radiation pulmonary fibrosis (RPF). During radiation treatment, not only are tumor cells targeted, but normal tissue cells, including alveolar epithelial cells and vascular endothelial cells, also sustain damage. Within the lungs, ionizing radiation boosts the intracellular levels of reactive oxygen species across various cell types. This elevation precipitates the release of cytokines and chemokines, coupled with the infiltration of inflammatory cells, culminating in the onset of RP. This pulmonary inflammatory response can persist, spanning a duration from several months to years, ultimately progressing to RPF. This review aims to explore the alterations in cytokine and chemokine release and the influx of immune cells post-ionizing radiation exposure in the lungs, offering insights for the prevention and management of RILI.

Macrophage-based delivery of anti-fibrotic proteins alleviates bleomycin-induced pulmonary fibrosis in mice

Idiopathic pulmonary fibrosis (IPF) is a fatal interstitial lung disease characterized by chronic, progressive, and fibrotic lung injury. Although remarkable progress has been made toward understanding the pathogenesis of PF, finding more effective treatments for this fatal disease remains a challenge. In this study, we describe an innovative macrophage-based approach to deliver anti-fibrotic protein to the lung and inhibit PF in a mouse model of bleomycin (BLM)-induced lung injury. We engineered macrophages to continuously secrete three types of proteins: interleukin-10, which prevents inflammation; TGFRcFc, a soluble truncated TGF-βR2 that blocks TGF-β; and CD147, which induces matrix metalloproteinases (MMPs) and causes collagen degradation. Infusing these engineered macrophages into the lungs of BLM-induced PF mouse models in an optimal pattern significantly ameliorated PF in mice. Specifically, the most effective therapeutic outcome was achieved by infusing IL-10-secreting macrophages on day 1, followed by TGFRcFc-secreting macrophages on day 7 and CD147-secreting macrophages on day 14 into the same mice after BLM treatment. Our data suggest that macrophage-based delivery of anti-fibrotic proteins to the lungs is a promising therapy for fibrotic lung disorders.

IPW-5371 mitigates the delayed effects of acute radiation exposure in WAG/RijCmcr rats when started 15 days after PBI with bone marrow sparing

PURPOSE

To test IPW-5371 for the mitigation of the delayed effects of acute radiation exposure (DEARE). Survivors of acute radiation exposure are at risk for developing delayed multi-organ toxicities; however, there are no FDA-approved medical countermeasures (MCM) to mitigate DEARE.

METHODS

WAG/RijCmcr female rat model of partial-body irradiation (PBI), by shielding part of one hind leg, was used to test IPW-5371 (7 and 20 mg kg-1 d-1) for mitigation of lung and kidney DEARE when started 15 d after PBI. Rats were fed known amounts of IPW-5371 using a syringe, instead of delivery by daily oral gavage, sparing exacerbation of esophageal injury by radiation. The primary endpoint, all-cause morbidity was assessed over 215 d. Secondary endpoints: body weight, breathing rate and blood urea nitrogen were also assessed.

RESULTS

IPW-5371 enhanced survival (primary endpoint) as well as attenuated secondary endpoints of lung and kidney injuries by radiation.

CONCLUSION

To provide a window for dosimetry and triage, as well as avoid oral delivery during the acute radiation syndrome (ARS), the drug regimen was started at 15 d after 13.5 Gy PBI. The experimental design to test mitigation of DEARE was customized for translation in humans, using an animal model of radiation that was designed to simulate a radiologic attack or accident. The results support advanced development of IPW-5371 to mitigate lethal lung and kidney injuries after irradiation of multiple organs.

Prevention and treatment of radiation-induced lung injury

Radiation-induced lung injury (RILI) is a common complication in cancer patients receiving local thoracic radiation and bone marrow transplantation conditioning. It is divided into early-stage radiation pneumonitis and advanced radiation fibrosis of the lung. This severely hampers the quality of life and survival of cancer patients. Meanwhile, RILI is a major factor limiting radiation doses in clinical practice, which affects the local control of cancer. Unfortunately, the mechanism of RILI is still not well defined, and there are no treatment options available for these patients. In this review we summarize the methods and agents used for the treatment and prevention of RILI, with the aim of increasing understanding of RILI.

Attenuation of Radiation-Induced Lung Injury by Hyaluronic Acid Nanoparticles

Purpose

Therapeutic thorax irradiation as an intervention in lung cancer has its limitations due to toxic effects leading to pneumonitis and/or pulmonary fibrosis. It has already been confirmed that hyaluronic acid (HA), an extracellular matrix glycosaminoglycan, is involved in inflammation disorders and wound healing in lung tissue. We examined the effects after gamma irradiation of hyaluronic acid nanoparticles (HANPs) applied into lung prior to that irradiation in a dose causing radiation-induced pulmonary injuries (RIPI).

Materials and Methods

Biocompatible HANPs were first used for viability assay conducted on the J774.2 cell line. For in vivo experiments, HANPs were administered intratracheally to C57Bl/6 mice 30 min before thoracic irradiation by 17 Gy. Molecular, cellular, and histopathological parameters were measured in lung and peripheral blood at days 113, 155, and 190, corresponding to periods of significant morphological and/or biochemical alterations of RIPI.

Results

Modification of linear hyaluronic acid molecule into nanoparticles structure significantly affected the physiological properties and caused long-term stability against ionizing radiation. The HANPs treatments had significant effects on the expression of the cytokines and particularly on the pro-fibrotic signaling pathway in the lung tissue. The radiation fibrosis phase was altered significantly in comparison with a solely irradiated group.

Conclusions

The present study provides evidence that application of HANPs caused significant changes in molecular and cellular patterns associated with RIPI. These findings suggest that HANPs could diminish detrimental radiation-induced processes in lung tissue, thereby potentially decreasing the extracellular matrix degradation leading to lung fibrosis.

The Yin and Yang of Cytoreductive SBRT in Oligometastases and Beyond

Background: Oligometastatic disease has emerged as a possibly distinct metastatic phenotype in numerous cancer histologies. With the advancement in treatment modalities including stereotactic body radiation therapy (SBRT), certain patients may derive benefits from local ablative therapy. SBRT alone has already shown to have potential benefits in certain oligometastatic disease types. However, more understanding of the immunologic modulation and microenvironment is needed to guide which patients may benefit from SBRT alone or with combination therapy, if at all. Purpose: The purpose of this review is to offer an update on the emerging data testing SBRT combined with immunotherapy, review the pro-inflammatory and immunosuppressive effects of the tumor microenvironment, discuss novel molecular targets used to augment the immune response, and review potential methods used to decrease toxicity in order to improve the therapeutic ratio.

Cytokines and radiation-induced pulmonary injuries

Radiation therapy is one of the most common treatment strategies for thorax malignancies. One of the considerable limitations of this therapy is its toxicity to normal tissue. The lung is the major dose-limiting organ for radiotherapy. That is because ionizing radiation produces reactive oxygen species that induce lesions, and not only is tumor tissue damaged, but overwhelming inflammatory lung damage can occur in the alveolar epithelium and capillary endothelium. This damage may result in radiation-induced pneumonitis and/or fibrosis. While describing the lung response to irradiation generally, the main focus of this review is on cytokines and their roles and functions within the individual stages. We discuss the relationship between radiation and cytokines and their direct and indirect effects on the formation and development of radiation injuries. Although this topic has been intensively studied and discussed for years, we still do not completely understand the roles of cytokines. Experimental data on cytokine involvement are fragmented across a large number of experimental studies; hence, the need for this review of the current knowledge. Cytokines are considered not only as molecular factors involved in the signaling network in pathological processes, but also for their diagnostic potential. A concentrated effort has been made to identify the significant immune system proteins showing positive correlation between serum levels and tissue damages. Elucidating the correlations between the extent and nature of radiation-induced pulmonary injuries and the levels of one or more key cytokines that initiate and control those damages may improve the efficacy of radiotherapy in cancer treatment and ultimately the well-being of patients.

CpG-oligodeoxynucleotides may be effective for preventing ionizing radiation induced pulmonary fibrosis

Pulmonary fibrosis is a serious adverse effect of radiotherapy for thoracic tumor, which is believed to be a process that is tightly regulated by the phenotype of the developing Th response after radiation. Here, we will investigate whether CpG-oligodeoxynucleotides (ODN) prevent radiation-induced pulmonary fibrosis by shifting the imbalance of Th1 and Th2 response and summarizes the possible mechanism. In this study, female C57BL/6 mice were chosen to preform pulmonary fibrosis model, the whole-thorax of mice was exposed to a single radiation dose of 15 Gy. When irradiated mice were administrated with CpG-ODN, forming of pulmonary fibrosis was significantly prevented. Th2-related cytokines (IL-4 and IL-13) expression decreased, Th1 related-cytokine (IFN-γ and IL-12) expression increased. Alveolar macrophage accumulation was reduced in irradiated tissue. Profibrotic cytokine TGF-β1 expression stayed at lower level. In TGF-β1-Smad-dependent pathways, TGF-β1, TβR and phosphor-Smad 2/3 were down regulated, and Smad 7 was up regulated. These suggested that CpG-ODN prevented pulmonary fibrosis after radiation. The mechanism might be associated with reduction of alveolar macrophages accumulation and profibrogenic cytokines secretion TGF-β1 through stimulating the combination of Th1-promoting and Th2-limiting responses after radiation, and finally inhibited the fibrosis-related downstream TGF-β1-Smad-dependent pathway.

Amelioration of Head and Neck Radiation-Induced Mucositis and Distant Marrow Suppression in Fanca-/- and Fancg-/- Mice by Intraoral Administration of GS-Nitroxide (JP4-039)

Squamous cell carcinomas of the head and neck are appearing with increased frequency in both marrow transplanted and non-transplanted Fanconi anemia (FA) patients. FA patients commonly display radiosensitivity of epithelial tissues, complicating effective radiotherapy. Fancd2^-/- mice (C57BL/6J and 129/Sv background) demonstrate epithelial tissue sensitivity to single-fraction or fractionated irradiation to the head and neck and distant marrow suppression (abscopal effect), both ameliorated by intraoral administration of the mitochondrial-targeted antioxidant, GS-nitroxide, JP4-039. We now report that mice of two other FA genotypes, Fancg^-/- (B6) and the most prevalent human genotype Fanca^-/- (129/Sv), also demonstrate: 1. reduced longevity of hematopoiesis in long-term bone marrow cultures; 2. radiosensitivity of bone marrow stromal cell lines; and 3. head and neck radiation-induced severe mucositis and abscopal suppression of distant marrow hematopoiesis. Intraoral administration of JP4-039/F15, but not non-mitochondrial-targeted 4-amino-Tempo/F15 or F15 alone, prior to each radiation treatment ameliorated both local and abscopal radiation effects. Head and neck irradiated TGF-β-resistant SMAD3^-/- (129/Sv) mice and double-knockout SMAD3^-/- Fancd2^-/- (129/Sv) mice treated daily with TGF-β receptor antagonist, LY364947, still displayed abscopal bone marrow suppression, implicating a non-TGF-β mechanism. Thus, amelioration of both local normal tissue radiosensitivity and distant marrow suppression by intraoral administration of JP4-039 in Fancg^-/- and Fanca^-/- mice supports a clinical trial of this locally administered normal tissue radioprotector and mitigator during head and neck irradiation in FA patients.

IPW-5371 Proves Effective as a Radiation Countermeasure by Mitigating Radiation-Induced Late Effects

There is an ongoing and significant need for radiation countermeasures to reduce morbidities and mortalities associated with exposure of the heart and lungs from a radiological or nuclear incidents. Radiation-induced late effects occur months to years after exposure, stemming from significant tissue damage and remodeling, resulting in fibrosis and loss of function. TGF-β is reported to play a role in both pulmonary and cardiac fibrosis. We investigated the ability of a small molecule TGF-β receptor 1 inhibitor, IPW-5371, to mitigate the effects of thoracic irradiation in C57L/J mice, a murine model that most closely resembles that observed in humans in the induction of fibrosis and dose response. To simulate a radiological event, radiation was administered in two doses: 5 Gy total-body irradiation (eliciting a whole-body response) and immediately after that, a thoracic "top-up" of 6.5 Gy irradiation, for a total dose of 11.5 Gy to the thorax. IPW-5371 was administered once daily, orally, starting 24 h postirradiation for 6 or 20 weeks at a dose of 10 mg/kg or 30 mg/kg. Animals were monitored for a period of 180 days for survival, and cardiopulmonary injury was assessed by echocardiography, breathing rate and arterial oxygen saturation. Exposure of the thorax (11.5 Gy) induced both pulmonary and cardiac injury, resulting in a reduced life span with median survival of 135 days. IPW-5371 treatment for 6 weeks, at both 10 mg/kg and 30 mg/kg, delayed disease onset and mortality, with median survival of 165 days. Twenty weeks of IPW-5371 treatment at 30 mg/kg preserved arterial O₂ saturation and cardiac contractile reserve and resulted in significant decreases in breathing frequency and cardiac and pulmonary fibrosis. This led to dramatic improvement in survival compared to the irradiated, vehicle-treated group (P < 0.001), and was statistically insignificant from the nonirradiated group. We observed that IPW-5371 treatment resulted in decreased pSmad3 tissue levels, confirming the effect of IPW-5371 on TGF-β signaling. These results demonstrate that IPW-5371 represents a potentially promising radiation countermeasure for the treatment of radiation-induced late effects.

Immunological Aspect of Radiation-Induced Pneumonitis, Current Treatment Strategies, and Future Prospects

Delivery of high doses of radiation to thoracic region, particularly with non-small cell lung cancer patients, becomes difficult due to subsequent complications arising in the lungs of the patient. Radiation-induced pneumonitis is an early event evident in most radiation exposed patients observed within 2-4 months of treatment and leading to fibrosis later. Several cytokines and inflammatory molecules interplay in the vicinity of the tissue developing radiation injury leading to pneumonitis and fibrosis. While certain cytokines may be exploited as biomarkers, they also appear to be a potent target of intervention at transcriptional level. Initiation and progression of pneumonitis and fibrosis thus are dynamic processes arising after few months to year after irradiation of the lung tissue. Currently, available treatment strategies are challenged by the major dose limiting complications that curtails success of the treatment as well as well being of the patient's future life. Several approaches have been in practice while many other are still being explored to overcome such complications. The current review gives a brief account of the immunological aspects, existing management practices, and suggests possible futuristic approaches.

Glycyrrhetinic acid alleviates radiation-induced lung injury in mice

Radiation-induced lung injury (RILI) is a common complication of thoracic radiotherapy, but efficacious therapy for RILI is lacking. This study ascertained whether glycyrrhetinic acid (GA; a functional hydrolyzed product of glycyrrhizic acid, which is extracted from herb licorice) can protect against RILI and investigated its relationship to the transforming growth factor (TGF)-β1/Smads signaling pathway. C57BL/6 mice were divided into four groups: a control group, a GA group and two irradiation (IR) groups. IR groups were exposed to a single fraction of X-rays (12 Gy) to the thorax and administered normal saline (IR + NS group) or GA (IR + GA group). Two days and 17 days after irradiation, histologic analyses were performed to assess the degree of lung injury, and the expression of TGF-β1, Smad2, Smad3 and Smad7 was recorded. GA administration mitigated the histologic changes of lung injury 2 days and 17 days after irradiation. Protein and mRNA expression of TGF-β1, Smad2 and Smad3, and the mRNA level of Smad7, in lung tissue were significantly elevated after irradiation. GA decreased expression of TGF-β1, Smad2 and Smad3 in lung tissue, but did not increase Smad7 expression. GA can protect against early-stage RILI. This protective effect may be associated with inhibition of the TGF-β1/Smads signaling pathway.

Lung

The lungs are particularly sensitive to RT, and are often the primary dose-limiting structure during thoracic therapy.

The alveolar/capillary units and pneumocytes within the alveoli appear to be particularly sensitive to RT.

Hypoxia may be important in the underlying physiology of RT-associated lung injury.

The cytokine transforming growth factor-beta (TGF-β), plays an important role in the development of RT-induced fibrosis.

The histopathological changes observed in the lung after RT are broadly characterized as diffuse alveolar damage.

The interaction between pre-treatment PFTs and the risk of symptomatic lung injury is complex. Similarly, the link between changes in PFTs and the development of symptoms is uncertain.

The incidence of symptomatic lung injury increases with increase in most dosimetric parameters. The mean lung dose (MLD) and V20 have been the most-often considered parameters. MLD might be a preferable metric since it considers the entire 3D dose distribution.

Radiation to the lower lobes appears to be more often associated with clinical symptoms than is radiation to the upper lobes. This might be related to incidental cardiac irradiation. In pre-clinical models, there appears to be a complex interaction between lung and heart irradiation.

TGF-β has been suggested in several studies to predict for RT-induced lung injury, but the data are still somewhat inconsistent.

Oral prednisone (Salinas and Winterbauer 1995), typically 40–60 mg daily for 1–2 weeks with a slow taper, is usually effective in treating pneumonitis. There are no widely accepted treatments for fibrosis.

A number of chemotherapeutic agents have been suggested to be associated with a range of pulmonary toxicities.

The impact of the myeloid response to radiation therapy

Radiation therapy is showing potential as a partner for immunotherapies in preclinical cancer models and early clinical studies. As has been discussed elsewhere, radiation provides debulking, antigen and adjuvant release, and inflammatory targeting of effector cells to the treatment site, thereby assisting multiple critical checkpoints in antitumor adaptive immunity. Adaptive immunity is terminated by inflammatory resolution, an active process which ensures that inflammatory damage is repaired and tissue function is restored. We discuss how radiation therapy similarly triggers inflammation followed by repair, the consequences to adaptive immune responses in the treatment site, and how the myeloid response to radiation may impact immunotherapies designed to improve control of residual cancer cells.

Expression of Angiotensin II and Aldosterone in Radiation-induced Lung Injury

OBJECTIVE

Radiation-induced lung injury (RILI) is the most common, dose-limiting complication in thoracic malignancy radiotherapy. Considering its negative impact on patients and restrictions to efficacy, the mechanism of RILI was studied.

METHODS

Wistar rats were locally irradiated with a single dose of 0, 16, and 20 Gy to the right half of the lung to establish a lung injury model. Two and six months after irradiation, the right half of the rat lung tissue was removed, and the concentrations of TGF-β1, angiotensin II, and aldosterone were determined via enzyme-linked immunosorbent assay.

RESULTS

Statistical differences were observed in the expression levels of angiotensin II and aldosterone between the non-irradiation and irradiation groups. Moreover, the expression level of the angiotensin II-aldosterone system increased with increasing doses, and the difference was still observed as time progressed.

CONCLUSIONS

Angiotensin II-aldosterone system has an important pathophysiological function in the progression of RILI.

Gene-modified mesenchymal stem cells protect against radiation-induced lung injury

Radiation-induced lung injury (RILI) presents a common and major obstacle in the radiotherapy of thoracic cancers. The aim of this study was to examine whether RILI could be alleviated by mesenchymal stem cells (MSCs) expressing soluble transforming growth factor-β (TGF-β) type II receptor via an adenovirus (Ad-sTβR). Here, we systemically administered male MSCs into female mice challenged with thoracic irradiation. The data showed that either MSCs or Ad-sTβR transduced MSCs (Ad-sTβR-MSCs) specifically migrated into radiation-injured lung. Ad-sTβR-MSCs obviously alleviated lung injury, as reflected by survival and histopathology data, as well as the assays of malondialdehyde (MDA), hydroxyproline, plasma cytokines, and the expression of connective tissue growth factor (CTGF) and α-smooth muscle actin (α-SMA). Furthermore, MSCs and Ad-sTβR-MSCs could adopt the characteristics of alveolar type II (ATII) cells. However, the MSCs levels in the lungs were relatively low to account for the noted therapeutic effects, suggesting the presence of other mechanisms. In vivo, MSCs-conditioned medium (MSCs CM) significantly attenuated RILI. In vitro, MSCs CM protected ATII cells against radiation-induced apoptosis and DNA damage, and modulated the inflammatory response, indicating the beneficial effects of MSCs are largely due to its paracrine activity. Our results provide a novel insight for RILI therapy that currently lack efficient treatments.

Cytokines in radiobiological responses: a review

Cytokines function in many roles that are highly relevant to radiation research. This review focuses on how cytokines are structurally organized, how they are induced by radiation, and how they orchestrate mesenchymal, epithelial and immune cell interactions in irradiated tissues. Pro-inflammatory cytokines are the major components of immediate early gene programs and as such can be rapidly activated after tissue irradiation. They converge with the effects of ionizing radiation in that both generate free radicals including reactive oxygen and nitrogen species (ROS/RNS). "Self" molecules secreted or released from cells after irradiation feed the same paradigm by signaling for ROS and cytokine production. As a result, multilayered feedback control circuits can be generated that perpetuate the radiation tissue damage response. The pro-inflammatory phase persists until such times as perceived challenges to host integrity are eliminated. Antioxidant, anti-inflammatory cytokines then act to restore homeostasis. The balance between pro-inflammatory and anti-inflammatory forces may shift to and fro for a long time after radiation exposure, creating waves as the host tries to deal with persisting pathogenesis. Individual cytokines function within socially interconnected groups to direct these integrated cellular responses. They hunt in packs and form complex cytokine networks that are nested within each other so as to form mutually reinforcing or antagonistic forces. This yin-yang balance appears to have redox as a fulcrum. Because of their social organization, cytokines appear to have a considerable degree of redundancy and it follows that an elevated level of a specific cytokine in a disease situation or after irradiation does not necessarily implicate it causally in pathogenesis. In spite of this, "driver" cytokines are emerging in pathogenic situations that can clearly be targeted for therapeutic benefit, including in radiation settings. Cytokines can greatly affect intrinsic cellular radiosensitivity, the incidence and type of radiation tissue complications, bystander effects, genomic instability and cancer. Minor and not so minor, polymorphisms in cytokine genes give considerable diversity within populations and are relevant to causation of disease. Therapeutic intervention is made difficult by such complexity; but the potential prize is great.

Mitigation of lung injury after accidental exposure to radiation

There is a serious need to develop effective mitigators against accidental radiation exposures. In radiation accidents, many people may receive nonuniform whole-body or partial-body irradiation. The lung is one of the more radiosensitive organs, demonstrating pneumonitis and fibrosis that are believed to develop at least partially because of radiation-induced chronic inflammation. Here we addressed the crucial questions of how damage to the lung can be mitigated and whether the response is affected by irradiation to the rest of the body. We examined the widely used dietary supplement genistein given at two dietary levels (750 or 3750 mg/kg) to Fischer rats irradiated with 12 Gy to the lung or 8 Gy to the lung + 4 Gy to the whole body excluding the head and tail (whole torso). We found that genistein had promising mitigating effects on oxidative damage, pneumonitis and fibrosis even at late times (36 weeks) when drug treatment was initiated 1 week after irradiation and stopped at 28 weeks postirradiation. The higher dose of genistein showed no greater beneficial effect. Combined lung and whole-torso irradiation caused more lung-related severe morbidity resulting in euthanasia of the animals than lung irradiation alone.

Adjuvant therapy with agonistic antibodies to CD134 (OX40) increases local control after surgical or radiation therapy of cancer in mice

The tumor recurrence from residual local or micrometastatic disease remains a problem in cancer therapy. In patients with soft tissue sarcoma and the patients with inoperable nonsmall cell lung cancer, local recurrence is common and significant mortality is caused by the subsequent emergence of metastatic disease. Thus, although the aim of the primary therapy is curative, the outcome may be improved by additional targeting of residual microscopic disease. We display in a murine model that surgical removal of a large primary sarcoma results in local recurrence in approximately 50% of animals. Depletion of CD8 T cells results in local recurrence in 100% of animals, indicating that these cells are involved in the control of residual disease. We further show that systemic adjuvant administration of αOX40 at surgery eliminates local recurrences. In this model, αOX40 acts to directly enhance tumor antigen-specific CD8 T-cell proliferation in the lymph node draining the surgical site, and results in increased tumor antigen-specific cytotoxicity in vivo. These results are also corroborated in a murine model of hypofractionated radiation therapy of lung cancer. Administration of αOX40 in combination with radiation significantly extended the survival compared with either agent alone, and resulted in a significant proportion of long-term tumor-free survivors. We conclude that αOX40 increases tumor antigen-specific CD8 T-cell cytotoxic activity resulting in improved endogenous immune control of residual microscopic disease, and we propose that adjuvant αOX40 administration may be a valuable addition to surgical and radiation therapy for cancer.

Radiation-induced liver fibrosis is mitigated by gene therapy inhibiting transforming growth factor-β signaling in the rat

PURPOSE

We determined whether anti-transforming growth factor-β (TGF-β) intervention could halt the progression of established radiation-induced liver fibrosis (RILF).

METHODS AND MATERIALS

A replication-defective adenoviral vector expressing the extracellular portion of human TβRII and the Fc portion of immunoglobulin G fusion protein (AdTβRIIFc) was produced. The entire rat liver was exposed to 30 Gy irradiation to generate a RILF model (RILFM). Then, RILFM animals were treated with AdTβRIIFc (1 × 10(11) plaque-forming units [PFU] of TβRII), control virus (1 × 10(11) PFU of AdGFP), or saline. Delayed radiation liver injury was assessed by histology and immunohistochemistry. Chronic oxidative stress damage, hepatic stellate cell activation, and hepatocyte regeneration were also analyzed.

RESULTS

In rats infected with AdTβRIIFc, fibrosis was significantly improved compared with rats treated with AdGFP or saline, as assessed by histology, hydroxyproline content, and serum level of hyaluronic acid. Compared with AdGFP rats, AdTβRIIFc-treated rats exhibited decreased oxidative stress damage and hepatic stellate cell activation and preserved liver function.

CONCLUSIONS

Our results demonstrate that TGF-β plays a critical role in the progression of liver fibrosis and suggest that anti-TGF-β intervention is feasible and ameliorates established liver fibrosis. In addition, chronic oxidative stress may be involved in the progression of RILF.

Imatinib therapy reduces radiation-induced pulmonary mast cell influx and delays lung disease in the mouse

PURPOSE

Radiotherapy can induce the inflammatory response of alveolitis and the excessive repair response of fibrosis through incompletely defined mechanisms. In previous murine studies we showed the alveolitis response to thoracic irradiation to correlate with pulmonary mast cell numbers and fibrosis severity to partially depend on the extent of alveolitis. Herein we investigate whether the mast cell blocker imatinib reduces the alveolitis and/or fibrosis response to irradiation.

MATERIAL AND METHODS

Mice of three strains received 18 Gy whole thorax irradiation and a subset of these were treated with imatinib (100 mg/kg) daily from the day of irradiation until euthanasia due to the presentation of distress symptoms.

RESULTS

Imatinib treatment increased the post irradiation survival time of the mice by an average of 23% and significantly reduced the pulmonary mast cell influx. The alveolitis and fibrosis phenotypes, evident histologically, were not altered by imatinib treatment in mice euthanised upon presentation of respiratory distress. The imatinib treated mice did, however, have less disease than did mice receiving radiation alone, when both groups were assessed at a common time point.

CONCLUSIONS

We conclude that imatinib treatment reduces radiation-induced mast cell influx into the lungs and delays the alveolitis or fibrosis response of mice.

Role of Radiation-induced TGF-beta Signaling in Cancer Therapy

TGF-β signaling regulates several different biological processes involving cell-growth, differentiation, apoptosis, motility, angiogenesis, epithelial mesenchymal transition and extracellular matrix production that affects embryonic development and pathogenesis of various diseases, including cancer, its effects depending on the cellular context and physiological environment. Growth suppression mediated by TGF-β signaling often associated with inhibition of c-myc, cdks and induction of p15, p27, Bax and p21. Despite its growth inhibitory effect, in certain conditions TGF-β may act as a promoter of cell proliferation and invasion. Loss of responsiveness to growth suppression by TGF-β due to mutation or loss of TGF-beta type II receptor (TβRII) and Smad4 in several different cancer cells are reported. In addition, TGF-β binding to its receptor activates many non-canonical signaling pathways. Radiation induced TGF-β is primarily involved in normal tissue injury and fibrosis. Seminal studies from our group have used radio-adjuvant therapies, involving classical components of the pathway such as TβRII and SMAD4 to overcome the growth promoting effects of TGF-β. The main impediment in the radiation-induced TGF-β signaling is the induction of SMAD7 that blocks TGF-β signaling in a negative feedback manner. It is well demonstrated from our studies that the use of neutralizing antibodies against TGF- β can render a robust radio-resistant effect. Thus, understanding the functional interactions of TGF-β signaling components of the pathway with other molecules may help tailor appropriate adjuvant radio-therapeutic strategies for treatment of solid tumors.

Protective effects of berberine on radiation-induced lung injury via intercellular adhesion molecular-1 and transforming growth factor-beta-1 in patients with lung cancer

PURPOSE

To investigate the protective effects of berberine on radiation-induced lung injury (RILI) in non-small cell lung cancer (NSCLC) patients treated with radiotherapy.

PATIENTS AND METHODS

In this randomised, double-blind study, 90 patients with NSCLC were divided into two groups. The trial group received radiation therapy plus berberine, and the control group received radiation therapy plus a placebo for 6 weeks. Soluble intercellular adhesion molecular-1 (sICAM-1) and transforming growth factor-beta-1 (TGF-beta1) were measured. RILI and pulmonary function were evaluated at 6 weeks and 6 months after treatment, respectively.

RESULTS

Of the 90 patients enroled, 43 in the control group and 42 in the trial group completed the study. The incidence of RILI was significantly lower in the trial group at 6 weeks and 6 months than that in the control group (45.2% versus 72.1% and 35.7% versus 65.1%, respectively, both P<0.05). sICAM-1 levels in the trial group were significantly lower at weeks 6 and 12 (373.64+/-89.33 versus 459.53+/-123.59 and 447.83+/-111.21 versus 513.91+/-150.46, both P<0.01), and plasma TGF-beta1 levels were lower at week 3 and 6 (5.43+/-1.47 versus 6.22+/-1.78 and 5.93+/-2.39 versus 7.67+/-2.74, P<0.05 and 0.01, respectively) in comparison with the control group. Significant differences were observed in FEV1 (P=0.033) and DLCO (P=0.003) between patients receiving berberine and those receiving placebo. Independent-samples T-test showed reductions from baseline FVC at week 6 (P<0.05), and FEV1 and DLCO at month 6 (P<0.05 and 0.01, respectively) in the trial group were significantly smaller than that in the control group.

CONCLUSION

Berberine significantly reduced the incidence of RILI, improved PF and decreased the levels of sICAM-1 and TGF-beta1. The exact mechanisms remain to be further explored.

Inhibition of integrin alpha(v)beta6, an activator of latent transforming growth factor-beta, prevents radiation-induced lung fibrosis

RATIONALE

In experimental models, lung fibrosis is dependent on transforming growth factor (TGF)-beta signaling. TGF-beta is secreted in a latent complex with its propeptide, and TGF-beta activators release TGF-beta from this complex. Because the integrin alpha(v)beta6 is a major TGF-beta activator in the lung, inhibition of alpha(v)beta6-mediated TGF-beta activation is a logical strategy to treat lung fibrosis.

OBJECTIVES

To determine, by genetic and pharmacologic approaches, whether murine radiation-induced lung fibrosis is dependent on alpha(v)beta6.

METHODS

Wild-type mice, alpha(v)beta6-deficient (Itgb6-/-) mice, and mice heterozygous for a Tgfb1 mutation that eliminates integrin-mediated activation (Tgfb1(+/RGE)) were exposed to 14 Gy thoracic radiation. Some mice were treated with an anti-alpha(v)beta6 monoclonal antibody or a soluble TGF-beta receptor fusion protein. Alpha(v)beta6 expression was determined by immunohistochemistry. Fibrosis, inflammation, and gene expression patterns were assessed 20-32 weeks postirradiation.

MEASUREMENTS AND MAIN RESULTS

Beta6 integrin expression increased within the alveolar epithelium 18 weeks postirradiation, just before onset of fibrosis. Itgb6-/- mice were completely protected from fibrosis, but not from late radiation-induced mortality. Anti-alpha(v)beta6 therapy (1-10 mg/kg/wk) prevented fibrosis, but only higher doses (6-10 mg/kg/wk) caused lung inflammation similar to that in Itgb6-/- mice. Tgfb1-haploinsufficient mice were also protected from fibrosis.

CONCLUSIONS

Alpha(v)beta6-mediated TGF-beta activation is required for radiation-induced lung fibrosis. Together with previous data, our results demonstrate a robust requirement for alpha(v)beta6 in distinct fibrosis models. Inhibition of alphavbeta6-mediated TGF-beta activation is a promising new approach for antifibrosis therapy.

The predictive role of plasma TGF-beta1 during radiation therapy for radiation-induced lung toxicity deserves further study in patients with non-small cell lung cancer

BACKGROUND

This study aimed to further investigate the role of circulating TGF-beta1 during radiation therapy (RT) in predicting radiation-induced lung toxicity (RILT).

METHODS AND MATERIALS

Patients with stages I-III non-small cell lung cancer treated with RT based therapy were included in this study. Platelet poor plasma was obtained pre-RT, at 2 and 4 weeks during-RT, and at the end of RT. TGF-beta1 was measured using an enzyme-linked immunosorbent assay. The primary endpoint for RILT was >or=grade 2 radiation pneumonitis or fibrosis.

RESULTS

Twenty-six patients with a minimum follow-up of 12 months were included. Six patients (23.1%) experienced >or=grade 2 RILT. There was no significant difference in absolute TGF-beta1 levels pre-RT, at 2 and 4 weeks during-RT, or at the end of RT between patients with and without RILT. The TGF-beta1 ratios (over the pre-RT levels) for patients with and without RILT at 2, 4 weeks during-, and the end of RT were 2.8+/-2.2 and 1.0+/-0.6 (P=0.123), 2.3+/-1.3 and 0.8+/-0.5 (P=0.001), 1.5+/-0.9 and 0.8+/-0.5 (P=0.098), respectively. Using 2.0 as a cut-off, the TGF-beta1 ratio at 4 weeks during-RT predicted RILT with a sensitivity and specificity of 66.7% and 95.0%, respectively.

CONCLUSION

Elevation of plasma TGF-beta1 level 4 weeks during-RT is significantly predictive of RILT. The role of plasma TGF-beta1 in predicting RILT deserves further study.

Molecular mechanisms of late normal tissue injury

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