Radiation-induced damage to mouse urothelial barrier

Radiation toxicity grading after chemoradiotherapy of canine urinary tract carcinomas: Comparing VRTOG to VRTOG_v2.0

Radiation toxicities may be underestimated after treatment of transitional cell carcinoma in dogs' lower urinary tract. Assessing acute and late toxicities and differentiating them from progressive disease (PD) impacts further therapeutic approach. We retrospectively assessed dogs treated with definitive-intent chemoradiotherapy (12 × 3.8 Gy, various first-line chemotherapeutics). Local tumour control, radiation toxicities and survival were evaluated. We classified radiation toxicities according to the previously published radiation toxicity scheme "VRTOG" as well as the updated version, "VRTOG_v2.0". Fourteen dogs with transitional cell carcinoma of bladder ± urethra (n = 8), +prostate (n = 3) or solely urethra (n = 3), were included. Median follow-up was 298 days (range 185-1798 days), median overall survival 305 days (95%CI = 209;402) and 28.6% deaths were tumour-progression-related. Acute radiation toxicity was mild and self-limiting with both classification systems: In VRTOG, 5 dogs showed grade 1, and 1 dog grade 2 toxicity. In VRTOG_v2.0, 2 dogs showed grade 1, 3 dogs grade 2, and 3 dogs grade 3 toxicity. Late toxicity was noted in 14.2% of dogs (2/14) with the VRTOG, both with grade 3 toxicity. With VRTOG_v2.0, a larger proportion of 42.9% of dogs (6/14) showed late toxicities: Four dogs grade 3 (persistent incontinence), 2 dogs grade 5 (urethral obstructions without PD resulting in euthanasia). At time of death, 5 dogs underwent further workup and only 3 were confirmed to have PD. With the updated VRTOG_v2.0 classification system, more dogs with probable late toxicity are registered, but it is ultimately difficult to distinguish these from disease progression as restaging remains to be the most robust determinant.

Progressive alteration of murine bladder elasticity in actinic cystitis detected by Brillouin microscopy

Bladder mechanical properties are critical for organ function and tissue homeostasis. Therefore, alterations of tissue mechanics are linked to disease onset and progression. This study aims to characterize the tissue elasticity of the murine bladder wall considering its different anatomical components, both in healthy conditions and in actinic cystitis, a state characterized by tissue fibrosis. Here, we exploit Brillouin microscopy, an emerging technique in the mechanobiology field that allows mapping tissue mechanics at the microscale, in non-contact mode and free of labeling. We show that Brillouin imaging of bladder tissues is able to recognize the different anatomical components of the bladder wall, confirmed by histopathological analysis, showing different tissue mechanical properties of the physiological bladder, as well as a significant alteration in the presence of tissue fibrosis. Our results point out the potential use of Brillouin imaging on clinically relevant samples as a complementary technique to histopathological analysis, deciphering complex mechanical alteration of each tissue layer of an organ that strongly relies on mechanical properties to perform its function.

Mesenchymal stem cells limit vascular and epithelial damage and restore the impermeability of the urothelium in chronic radiation cystitis

BACKGROUND

Cellular therapy seems to be an innovative therapeutic alternative for which mesenchymal stem cells (MSCs) have been shown to be effective for interstitial and hemorrhagic cystitis. However, the action of MSCs on chronic radiation cystitis (CRC) remains to be demonstrated. The aim of this study was to set up a rat model of CRC and to evaluate the efficacy of MSCs and their mode of action.

METHODS

CRC was induced by single-dose localized irradiation of the whole bladder using two beams guided by tomography in female Sprague-Dawley rat. A dose range of 20-80 Gy with follow-up 3-12 months after irradiation was used to characterize the dose effect and the kinetics of radiation cystitis in rats. For the treatment, the dose of 40 Gy was retained, and in order to potentiate the effect of the MSCs, MSCs were isolated from adipose tissue. After expansion, they were injected intravenously during the pre-chronic phase. Three injections of 5 million MSCs were administered every fortnight. Follow-up was performed for 12 months after irradiation.

RESULTS

We observed that the intensity and frequency of hematuria are proportional to the irradiation dose, with a threshold at 40 Gy and the appearance of bleeding from 100 days post-irradiation. The MSCs reduced vascular damage as well as damage to the bladder epithelium.

CONCLUSIONS

These results are in favor of MSCs acting to limit progression of the chronic phase of radiation cystitis. MSC treatment may afford real hope for all patients suffering from chronic radiation cystitis resistant to conventional treatments.

Intravesical IR-780 instillation prevents radiation cystitis by protecting urothelial integrity

PURPOSE

To explore an efficient preventive strategy for radiation cystitis.

METHODS

We instilled IR-780 into the bladders of rats 1 h before bladder irradiation, and its bio-distribution was observed at different times. Bladders were then examined for pathogenic alterations and inflammation levels by day 3 and week 12 postirradiation, and the functional characteristics of the bladder were tested via cystometry by week 12. Human uroepithelial sv-huc-1 cells were used to determine the effect of IR-780 on cell viability, regardless of irradiation. We measured the intracellular levels of oxidative stress, DNA damage, apoptosis proportion, and the expression of antioxidant proteases and apoptotic caspases in IR-780 pretreated cells after radiation.

RESULTS

IR-780 is localized in the urothelium after intravesical instillation in vivo. Ionizing radiation could induce acute impairment of the bladder urothelium and inflammation in the bladder on day 3. Fibrosis of the irradiated bladder progressed and eventually affected voiding function at 12 weeks. Treatment with IR-780 before irradiation ameliorated these changes. In vitro, IR-780 protected against cell viability and apoptosis of sv-huc-1 cells after irradiation. Additionally, IR-780 may assist in eliminating reactive oxygen species and repairing irradiation-induced DNA damage.

CONCLUSION

Our data indicate that IR-780 can be used before irradiation to prevent acute urinary mucosal injury and late bladder dysfunction. Moreover, early urothelial impairment plays a significant role in radiation cystitis development.

Molecular Mechanisms and Key Processes in Interstitial, Hemorrhagic and Radiation Cystitis

Simple Summary

Pathologies of the bladder are called cystitis. They cause discomfort for the patient. Due to persistent pain, bleeding, urinary incontinence, and uncontrolled urination, the chronic forms cause considerable degradation to patient quality of life. Currently, there is no curative treatment for the most severe forms. This is both an economic and a societal problem. Although the different forms of cystitis have different causes, they share common mechanisms. We propose to describe in detail the key processes and the associated mechanisms involved in abacterial cystitis.

Abstract

Cystitis is a bladder disease with a high rate of prevalence in the world population. This report focuses on Interstitial Cystitis (IC), Hemorrhagic Cystitis (HC) and Chronic Radiation Cystitis. These pathologies have different etiologies, but they share common symptoms, for instance, pain, bleeding, and a contracted bladder. Overall, treatments are quite similar for abacterial cystitis, and include bladder epithelium protective or anti-inflammatory agents, alleviating pain and reducing bleeding. This review summarizes the mechanisms that the pathologies have in common, for instance, bladder dysfunction and inflammation. Conversely, some mechanisms have been described as present in only one pathology, such as neural regulation. Based on these specificities, we propose identifying a mechanism that could be common to all the above-mentioned pathologies.

Understanding Molecular Mechanisms and Identifying Key Processes in Chronic Radiation Cystitis

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

Clinical characterization of radiation-associated muscle-invasive bladder cancer

OBJECTIVE

To characterize the presentation, patterns of care, and outcomes of radiation-associated muscle-invasive bladder cancer (RA-MIBC) compared to primary (non-radiation associated) MIBC. RA-MIBC has been suggested to represent a more aggressive disease variant and be more difficult to treat compared to primary (non-radiation associated) MIBC.

METHODS

We identified 60,090 patients diagnosed with MIBC between 1988-2015 using the Surveillance, Epidemiology, and End Results database and stratified patients based on whether radiation had been administered to a prior pelvic primary cancer. We used Fine-Gray competing risks regression to compare adjusted bladder cancer-specific mortality (BCSM) for RA-MIBC compared to primary MIBC.

RESULTS

There were 1,093 patients with RA-MIBC and 58,997 patients with primary MIBC. RA-MIBCs were more likely to be T4 at diagnosis (21.0% vs 17.3%, P < .001), and less likely to be node-positive (10.3% vs 17.1%, P < .001). The rate of 5-year BCSM was significantly higher for patients with RA-MIBC vs primary MIBC (56.1% vs 35.3%, AHR 1.24, P < .001), even after stratification by other tumor, treatment and patient-specific factors.

CONCLUSION

RA-MIBCs tended to present with higher grade and T stage disease and were less likely to receive curative treatment. Even when accounting for stage, grade, and receipt of treatment, patients with RA-MIBC had worse survival compared to those with primary MIBC. These findings suggest that RA-MIBC present unique clinical challenges and may also represent a biologically more aggressive disease compared to primary MIBC. Future research is needed to better understand the biology of RA-MIBC and develop improved treatment approaches.

Effect of irradiation on the expression of E-cadherin and β-catenin in early and late radiation sequelae of the urinary bladder and its modulation by NF-κB inhibitor thalidomide

Purpose

In a previous study we have shown in a mouse model that administration of nuclear factor-kappa B (NF-κB) inhibitor thalidomide has promising therapeutic effects on early radiation cystitis (ERC) and late radiation sequelae (LRS) of the urinary bladder. The aim of this study was to evaluate in the same mice the effect of thalidomide on adherens junction (AJ) proteins in ERC and LRS.

Methods

Urothelial expressions of E‑cadherin and β‑catenin were assessed by immunohistochemistry in formalin-fixed paraffin-embedded (FFPE) bladder specimens over 360 days post single-dose irradiation on day 0. First, the effect of irradiation on AJ expression and then effects of thalidomide on irradiation-induced AJ alterations were assessed using three different treatment times.

Results

Irradiation provoked a biphasic upregulation of E‑cadherin and β‑catenin in the early phase. After a mild decrease of E‑cadherin and a pronounced decrease of β‑catenin at the end of the early phase, both increased again in the late phase. Early administration of thalidomide (day 1–15) resulted in a steeper rise in the first days, an extended and increased expression at the end of the early phase and a higher expression of β‑catenin alone at the beginning of the late phase.

Conclusion

Upregulation of AJ proteins is an attempt to compensate irradiation-induced impairment of urothelial barrier function. Early administration of thalidomide improves these compensatory mechanisms by inhibiting NF-κB signaling and its interfering effects.

Pre-clinical Research on Bladder Toxicity After Radiotherapy for Pelvic Cancers: State-of-the Art and Challenges

Despite the dramatic advancements in pelvic radiotherapy, urinary toxicity remains a significant side-effect. The assessment of clinico-dosimetric predictors of radiation cystitis (RC) based on clinical data has improved substantially over the last decade; however, a thorough understanding of the physiopathogenetic mechanisms underlying the onset of RC, with its variegated acute and late urinary symptoms, is still largely lacking, and data from pre-clinical research is still limited. The aim of this review is to provide an overview of the main open issues and, ideally, to help investigators in orienting future research. First, anatomy and physiology of bladder, as well as the current knowledge of dose and dose-volume effects in humans, are briefly summarized. Subsequently, pre-clinical radiobiology aspects of RC are discussed. The findings suggest that pre-clinical research on RC in animal models is a lively field of research with growing interest in the development of new radioprotective agents. The availability of new high precision micro-irradiators and the rapid advances in small animal imaging might lead to big improvement into this field. In particular, studies focusing on the definition of dose and fractionation are warranted, especially considering the growing interest in hypo-fractionation and ablative therapies for prostate cancer treatment. Moreover, improvement in radiotherapy plans optimization by selectively reducing radiation dose to more radiosensitive substructures close to the bladder would be of paramount importance. Finally, thanks to new pre-clinical imaging platforms, reliable and reproducible methods to assess the severity of RC in animal models are expected to be developed.

Translational Aspects of Nuclear Factor-Kappa B and Its Modulation by Thalidomide on Early and Late Radiation Sequelae in Urinary Bladder Dysfunction

PURPOSE

This preclinical study aimed to investigate the role of nuclear factor (NF)-κB in early and late radiogenic sequelae of urinary bladder dysfunction in mice. Thalidomide was applied either during the early or late response phase to determine potential effects of NF-κB inhibition on functional bladder impairment.

METHODS AND MATERIALS

After pelvic irradiation on day 0, female C3H/Neu mice were observed over a period of 360 days and radiation response was evaluated for alterations in bladder functionality and NF-κB activation. Functionality was determined in graded dose experiments (14-24 Gy) and assessed by micturition frequency analysis and transurethral cystotonometry to reveal alterations in voiding and volume. The induction of the NF-κB proteins p50 and p65 was evaluated by immunohistochemistry in response to a single dose of 23 Gy (ED₉₀). Thalidomide (100 mg/kg/d) was applied intraperitoneally in 3 treatment groups: daily from day 1 to 15, daily from day 16 to 30, and in 2-day-intervals from day 150 to 180.

RESULTS

Immunohistochemical analysis showed a biphasic activation of p50 and p65 during the early radiation cystitis phase (day 1-30). After a transient decrease, p50, but not p65, was reactivated permanently leading to increased levels, which suggests an occurrence of chronic inflammation correlated with functional impairment. Both early thalidomide treatments reduced NF-κB activation and shifted the ED₅₀ value for early radiation cystitis and late radiation sequelae to higher doses.

CONCLUSIONS

These data clearly demonstrate the involvement of NF-κB signaling in the pathogenesis of radiation-induced urinary bladder dysfunction. Additionally, this study emphasizes that biological targeting of early radiogenic processes has enormous effect on chronic symptoms. The late administration of thalidomide showed no significant effect on functionality.

Radiation cystitis modeling: A comparative study of bladder fibrosis radio-sensitivity in C57BL/6, C3H, and BALB/c mice

A subset of patients receiving radiation therapy for pelvic cancer develop radiation cystitis, a complication characterized by mucosal cell death, inflammation, hematuria, and bladder fibrosis. Radiation cystitis can reduce bladder capacity, cause incontinence, and impair voiding function so severely that patients require surgical intervention. Factors influencing onset and severity of radiation cystitis are not fully known. We tested the hypothesis that genetic background is a contributing factor. We irradiated bladders of female C57BL/6, C3H, and BALB/c mice and evaluated urinary voiding function, bladder shape, histology, collagen composition, and distribution of collagen-producing cells. We found that the genetic background profoundly affects the severity of radiation-induced bladder fibrosis and urinary voiding dysfunction. C57BL/6 mice are most susceptible and C3H mice are most resistant. Irradiated C57BL/6 mouse bladders are misshapen and express more abundant collagen I and III proteins than irradiated C3H and BALB/c bladders. We localized Col1a1 and Col3a1 mRNAs to FSP1-negative stromal cells in the bladder lamina propria and detrusor. The number of collagen I and collagen III-producing cells can predict the average voided volume of a mouse. Collectively, we show that genetic factors confer sensitivity to radiation cystitis, establish C57BL/6 mice as a sensitive preclinical model, and identify a potential role for FSP1-negative stromal cells in radiation-induced bladder fibrosis.

An evaluation of the effect of bortezomib on radiation-induced urinary bladder dysfunction

PURPOSE

The urinary bladder is one major organ at risk in radiotherapy of pelvic malignancies. The radiation response manifests in early and chronic changes in bladder function. These are based on inflammatory effects and changes in urothelial cell function and proliferation. This study evaluates the effect of bortezomib as an anti-proliferative and anti-inflammatory compound in an established mouse bladder model. The early radiation-induced bladder dysfunction in the mouse occurs in two phases during the first month after irradiation (phase I: day 0-15, phase II: days 16-30).

MATERIALS AND METHODS

Daily bortezomib injections (0.02 mg/ml, subcutaneously) were administered between days 0-15 or 15-30 in separate groups. Single graded radiation doses were administered in five dose groups. Cystometry was carried out before (individual control) and during the first month after irradiation. When bladder capacity was decreased by ≥50%, mice were considered as responders. Statistical analysis was performed by the SPSS software version 24.

RESULTS

Daily bortezomib injections between days 0-15 resulted in a significant decrease in responders for phase I. There was no significant effect with daily bortezomib injections between days 16-30.

CONCLUSION

Two separate waves of acute radiation-induced urinary bladder dysfunction have distinct mechanisms that need further biological studies.

[Medical prevention and treatment of radiation-induced urological and nephrological complications]

Abdominal and pelvic irradiations play a major place in the management of patients with cancer and present a risk of acute and late side effects. Radiation-induced lesions can affect kidney or urological structures. These side effects can have an impact in the quality of life of patients. The aim of this article is to describe the physiopathology, the symptomatology, and the principles of management of radiation-induced nephropathy, uretheritis, cystitis, and urethritis.

Dual benefit of supplementary oral 5-aminolevulinic acid to pelvic radiotherapy in a syngenic prostate cancer model

BACKGROUND

Normal tissue damage caused by radiotherapy remains the largest dose-limiting factor in radiotherapy for cancer. Therefore, the aim of this study was to investigate the supplementary oral 5-aminolevulinic acid (ALA) to standard radiation therapy as a novel radioprotective approach that would not compromise the antitumor effect of radiation in normal rectal and bladder mucosa in a syngenic prostate cancer (PCa) model.

METHODS

To evaluate the radiosensitizing effect of ALA in vitro, clonogenic survival assays were performed in DU145, PC3, and MyC-CaP cell lines. To evaluate the effect of ALA in vivo a single dose (25 Gy) of radiation with or without ALA was given to healthy mice. Next, a syngenic PCa model of MyC-CaP cells in FVB mice was created, and multiple doses (12 Gy total) of radiation were administered to the mouse pelvic area with or without ALA administration. Resected tumors, recta, and urinary bladders were immunostained with antibodies against Ki-67, γ-H2AX, CD204, and uroplakin-III. Total RNA levels in recta and urinary bladders were analyzed via RT2 Profiler polymerase chain reaction (PCR) arrays related to "Stress & Toxicity PathwayFinder," "Mitochondria," and "Inflammasomes."

RESULTS

The addition of in vitro single or in vivo repeated administration of exogenous ALA acted as a radiosensitizer for PCa cells. Rectal toxicity was characterized by histological changes including loss of surface epithelium, fibrosis, severe DNA damage, and the aggregation of M2 macrophages. Urinary bladder toxicity was characterized by bladder wall thickening and urothelium denuding. The higher dose (300 mg/kg/day) of ALA exerted a better radioprotective profile than the lower dose (30 mg/kg/day) in normal recta and urinary bladders. Out of the 252 genes tested, 35 (13.4%) were detected as relevant genes which may be involved in the radioprotective role of ALA administration. These included interleukin-1a (IL-1a), IL-1b, IL-12, chemokine (C-X-C motif) ligand 1 (CXCL1), CXCL3, and NLRP3.

CONCLUSIONS

Our study provides novel and comprehensive insights into the dual benefits including radiosensitizing PCa tumor tissues and radioprotection of normal pelvic organs from radiation therapy. Knowledge of the underlying mechanism will facilitate the search for optimal treatment parameters for supplemental oral ALA during radiotherapy for PCa.

Impact of bladder volume on acute genitourinary toxicity in intensity modulated radiotherapy for localized and locally advanced prostate cancer

BACKGROUND AND PURPOSE

To evaluate the effect of changes in bladder volume during high-dose intensity-modulated-radiotherapy (IMRT) of prostate cancer on acute genitourinary (GU) toxicity and prospectively evaluate a simple biofeedback technique for reproducible bladder filling with the aim of reducing acute GU toxicity.

METHODS

One hundred ninety-three patients were trained via a biofeedback mechanism to maintain a partially filled bladder with a reproducible volume of 200-300 cc at planning CT and subsequently at each fraction of radiotherapy. We prospectively analyzed whether and to what extent the patients' ability to maintain a certain bladder filling influenced the degree of acute GU toxicity and whether cut-off values could be differentiated.

RESULTS

We demonstrated that the ability to reach a reproducible bladder volume above a threshold volume of 180 cc and maintain that volume via biofeedback throughout treatment predicts for a decrease in acute GU toxicity during curative high-dose IMRT of the prostate. Patients who were not able to reach a partial bladder filling to that cut-off value and were not able to maintain a partially filled bladder throughout treatment had a significantly higher risk of developing ≥grade 2 GU acute toxicity.

CONCLUSION

Our results support the hypothesis that a biofeedback training for the patient is an easy-to-apply, useful, and cost-effective tool for reducing acute GU toxicity in high-dose IMRT of the prostate. Patients who are not able to reach and maintain a certain bladder volume during planning and treatment-two independent risk factors-might need special consideration.

Acute radiation impacts contractility of guinea-pig bladder strips affecting mucosal-detrusor interactions

Radiation-induced bladder toxicity is associated with radiation therapy for pelvic malignancies, arising from unavoidable irradiation of neighbouring normal bladder tissue. This study aimed to investigate the acute impact of ionizing radiation on the contractility of bladder strips and identify the radiation-sensitivity of the mucosa vs the detrusor. Guinea-pig bladder strips (intact or mucosa-free) received ex vivo sham or 20Gy irradiation and were studied with in vitro myography, electrical field stimulation and Ca2+-fluorescence imaging. Frequency-dependent, neurogenic contractions in intact strips were reduced by irradiation across the force-frequency graph. The radiation-difference persisted in atropine (1μM); subsequent addition of PPADs (100μM) blocked the radiation effect at higher stimulation frequencies and decreased the force-frequency plot. Conversely, neurogenic contractions in mucosa-free strips were radiation-insensitive. Radiation did not affect agonist-evoked contractions (1μM carbachol, 5mM ATP) in intact or mucosa-free strips. Interestingly, agonist-evoked contractions were larger in irradiated mucosa-free strips vs irradiated intact strips suggesting that radiation may have unmasked an inhibitory mucosal element. Spontaneous activity was larger in control intact vs mucosa-free preparations; this difference was absent in irradiated strips. Spontaneous Ca2+-transients in smooth muscle cells within tissue preparations were reduced by radiation. Radiation affected neurogenic and agonist-evoked bladder contractions and also reduced Ca2+-signalling events in smooth muscle cells when the mucosal layer was present. Radiation eliminated a positive modulatory effect on spontaneous activity by the mucosa layer. Overall, the findings suggest that radiation impairs contractility via mucosal regulatory mechanisms independent of the development of radiation cystitis.

Dual effects of radiation bystander signaling in urothelial cancer: purinergic-activation of apoptosis attenuates survival of urothelial cancer and normal urothelial cells

Radiation therapy (RT) delivers tumour kill, directly and often via bystander mechanisms. Bladder toxicity is a dose limiting constraint in pelvic RT, manifested as radiation cystitis and urinary symptoms. We aimed to investigate the impact of radiation-induced bystander signaling on normal/cancer urothelial cells. Human urothelial cancer cells T24, HT1376 and normal urothelial cells HUC, SV-HUC were used. Cells were irradiated and studied directly, or conditioned medium from irradiated cells (CM) was transferred to naïve, cells. T24 or SV-HUC cells in the shielded half of irradiated flasks had increased numbers of DNA damage foci vs non-irradiated cells. A physical barrier blocked this response, indicating release of transmitters from irradiated cells. Clonogenic survival of shielded T24 or SV-HUC was also reduced; a physical barrier prevented this phenomenon. CM-transfer increased pro-apoptotic caspase-3 activity, increased cleaved caspase-3 and cleaved PARP expression and reduced survival protein XIAP expression. This effect was mimicked by ATP. ATP or CM evoked suramin-sensitive Ca²⁺-signals. Irradiation increased [ATP] in CM from T24. The CM-inhibitory effect on T24 clonogenic survival was blocked by apyrase, or mimicked by ATP. We conclude that radiation-induced bystander signaling enhances urothelial cancer cell killing via activation of purinergic pro-apoptotic pathways. This benefit is accompanied by normal urothelial damage indicating RT bladder toxicity is also bystander-mediated.

Evaluation of the Effects of Prostate Radiation Therapy on Occludin Expression and Ultrasonography Characteristics of the Bladder

PURPOSE

To evaluate the effects of radiation dose in prostate radiation therapy (RT) on occludin expression and ultrasonography characteristics of the bladder.

METHODS AND MATERIALS

Urine samples of 64 prostate RT patients were collected before, at regular intervals during, and 3 months after RT. Occludin expression analysis was performed, and bladder wall echogenicity and echotexture were investigated by ultrasound and the gray-scale histogram analysis method. The bladder equivalent uniform dose (EUD) was derived from individually produced dose treatment plan for each patient. Clinical scoring for bladder-specific symptoms was done using the Radiation Therapy Oncology Group Acute Radiation Morbidity Scoring Criteria Scale.

RESULTS

Thirty patients (47%) experienced at least 1 of the studied bladder symptoms (grade ≥1 endpoints), including urinary pain, frequency, urgency, straining, incontinence, hematuria, dysuria, and nocturia. For these patients there were significant changes in urine occludin levels after starting the treatment compared with the baseline urine samples (P=.023). The mean bladder EUD that caused a significant change in occludin level, which occurred after the 15th RT session, was 26.9 Gy (range, 13.2-36.5 Gy, P=.020). In all patients a significant reduction in bladder echogenicity (P=.0137) and a significant change in its echotexture (P=.047) was found after the 10th RT session, after which the EUD to the bladder reached 17.9 Gy (range, 8.8-24.3 Gy).

CONCLUSIONS

Significant changes in occludin expression level and bladder wall echogenicity and echotexture occurred during prostate RT. Our findings suggest that a significant reduction in bladder echogenicity and increase in occludin expression during treatment can be associated with acute urinary complications.

Modeling of chronic radiation-induced cystitis in mice

Purpose

Radiation cystitis (RC), a severe inflammatory bladder condition, develops as a side effect of pelvic radiation therapy in cancer patients. There are currently no effective therapies to treat RC, in part from the lack of preclinical model systems. In this study, we developed a mouse model for RC and used a Small Animal Radiation Research Platform to simulate the targeted delivery of radiation as used with human patients.

Methods and materials

To induce RC, C3H mice received a single radiation dose of 20 Gy delivered through 2 beams. Mice were subjected to weekly micturition measurements to assess changes in urinary frequency. At the end of the study, bladder tissues were processed for histology.

Results

Radiation was well-tolerated; no change in weight was observed in the weeks after treatment, and there was no hair loss at the irradiation sites. Starting at 17 weeks after treatment, micturition frequency was significantly higher in irradiated mice versus control animals. Pathological changes include fibrosis, inflammation, urothelial thinning, and necrosis. At a site of severe insult, we observed telangiectasia, absence of uroplakin-3 and E-cadherin relocalization.

Conclusions

We developed an RC model that mimics the human pathology and functional changes. Furthermore, radiation exposure attenuates the urothelial integrity long-term, allowing for potential continuous irritability of the bladder wall from exposure to urine. Future studies will focus on the underlying molecular changes associated with this condition and investigate novel treatment strategies.

The Therapeutic Effect of Adipose-Derived Mesenchymal Stem Cells for Radiation-Induced Bladder Injury

This study was designed to investigate the protective effect of adipose derived mesenchymal stem cells (AdMSCs) against radiation-induced bladder injury (RIBI). Female rats were divided into 4 groups: (a) controls, consisting of nontreated rats; (b) radiation-treated rats; (c) radiation-treated rats receiving AdMSCs; and (d) radiation-treated rats receiving AdMSCs conditioned medium. AdMSCs or AdMSCs conditioned medium was injected into the muscular layer of bladder 24 h after radiation. Twelve weeks after radiation, urinary bladder tissue was collected for histological assessment and enzyme-linked immunosorbent assay (ELISA) after metabolic cage investigation. At the 1 w, 4 w, and 8 w time points following cells injection, 3 randomly selected rats in RC group and AdMSCs group were sacrificed to track injected AdMSCs. Metabolic cage investigation revealed that AdMSCs showed protective effect for radiation-induced bladder dysfunction. The histological and ELISA results indicated that the fibrosis and inflammation within the bladder were ameliorated by AdMSCs. AdMSCs conditioned medium showed similar effects in preventing radiation-induced bladder dysfunction. In addition, histological data indicated a time-dependent decrease in the number of AdMSCs in the bladder following injection. AdMSCs prevented radiation induced bladder dysfunction and histological changes. Paracrine effect might be involved in the protective effects of AdMSCs for RIBI.

POMC expression of the urothelium of the urinary bladder of mice submitted to pelvic radiation

Objective:

Patients who have had pelvic radiotherapy as part of their cancer therapy may develop subsequent urinary bladder injury. The acute changes that the urothelium undergo after radiation are known, but the healing mechanism of the urothelium of the urinary bladder after pelvic radiotherapy is not clearly understood. Proopiomelanocortin (POMC) peptides, which have immunomodulatory effects, are produced locally in sites outside of the central nervous system. This study aims to determine the role of POMC expression in the urothelium during radiation injury.

Methods:

Twenty-four male Swiss Albino mice were divided into four groups. A single-fractioned 10 Gy of ionizing radiation was applied to the pelvic zone of all mice with Cobalt-60 radiotherapy. The first group 1, which consisted intact animal and not irradiated was the control group, and the second, third, and fourth groups were euthanized after 24 h (Group 2), 48 h (Group 3), and 7 days (Group 4) after irradiation. All bladders were prepared for histochemical analysis using hematoxylin eosin (H&E) and immunohistochemical analysis using anti-POMC antibody.

Results:

No morphological differences were seen in all the group samples stained with H&E. POMC expression of the urothelium of bladder tissue samples shows different staining levels. Group 1 (96.7 ± 7.68), Group 2 (88.3 ± 8.04), and Group 3 (85.10 ± 10.9) were very weakly stained, but the POMC immunoreactivity of Group 4 (113.0 ± 12.8) was observed to be strong.

Conclusion:

Expression of POMC from urothelium seems to prevent bladder damage from radiation supplying differentiation and restoration of the urothelium.

Basic Fibroblast Growth Factor Ameliorates Endothelial Dysfunction in Radiation-Induced Bladder Injury

This study was designed to explore the effect of basic fibroblast growth factor (bFGF) on radiation-induced endothelial dysfunction and histological changes in the urinary bladder. bFGF was administrated to human umbilical vein cells (HUVEC) or urinary bladder immediately after radiation. Reduced expression of thrombomodulin (TM) was indicated in the HUVEC and urinary bladder after treatment with radiation. Decreased apoptosis was observed in HUVEC treated with bFGF. Administration of bFGF increased the expression of TM in HUVEC medium, as well as in the urinary bladder at the early and delayed phases of radiation-induced bladder injury (RIBI). At the early phase, injection of bFGF increased the thickness of urothelium and reduced inflammation within the urinary bladder. At the delayed phase, bFGF was effective in reducing fibrosis within the urinary bladder. Our results indicate that endothelial dysfunction is a prominent feature of RIBI. Administration of bFGF can ameliorate radiation-induced endothelial dysfunction in urinary bladder and preserve bladder histology at early and delayed phases of RIBI.

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

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

Postradiation changes in tissues: evaluation by imaging studies with emphasis on fluorodeoxyglucose-PET/computed tomography and correlation with histopathologic findings

Efforts have been made to minimize the damage to adjacent normal tissues during radiotherapy, primarily by shifting from the use of conventional radiotherapy to more advanced techniques. Reviewing the overall pattern on combined anatomic and functional imaging can enhance diagnostic accuracy. Several radiotracers can be used; [(18)F]fluorodeoxyglucose is the most common. Familiarity with the type and timing of previous radiation therapy, the spectrum of imaging findings after radiation injury, and the appropriate use of the different radiotracers can be crucial. This article summarizes postradiation histologic findings and multimodality imaging findings, with emphasis on PET/computed tomography.

Mesenchymal stem cell therapy stimulates endogenous host progenitor cells to improve colonic epithelial regeneration

Patients who undergo pelvic radiotherapy may develop severe and chronic complications resulting from gastrointestinal alterations. The lack of curative treatment highlights the importance of novel and effective therapeutic strategies. We thus tested the therapeutic benefit of mesenchymal stem cells (MSC) treatment and proposed molecular mechanisms of action. MSC efficacy was tested in an experimental model of radiation-induced severe colonic ulceration histologically similar to that observed in patients. In this model, MSC from bone marrow were administered intravenously, immediately or three weeks (established lesions) after irradiation. MSC therapy reduces radiation-induced colonic ulceration and increases animal survival. MSC treatment induces therapeutic efficacy whatever the time of cell infusion. Infused-MSC engraft in the colon but also increase endogenous MSC mobilization in blood that have lasting benefits over time. In vitro analysis demonstrates that the MSC effect is mediated by paracrine mechanisms through the non-canonical WNT (Wingless integration site) pathway. In irradiated rat colons, MSC treatment increases the expression of the non-canonical WNT4 ligand by epithelial cells. The epithelial regenerative process is improved after MSC injection by stimulation of colonic epithelial cells positive for SOX9 (SRY-box containing gene 9) progenitor/stem cell markers. This study demonstrates that MSC treatment induces stimulation of endogenous host progenitor cells to improve the regenerative process and constitutes an initial approach to arguing in favor of the use of MSC to limit/reduce colorectal damage induced by radiation.

Hedgehog signaling influences gender-specific response of liver to radiation in mice

BACKGROUND

It is unclear why the response to radiation in the female liver is different from that of the male liver. Hedgehog (Hh) that remains latent in healthy adult livers is activated in the injured liver and promotes the proliferation of progenitors and myofibroblastic hepatic stellate cells, leading to hepatic fibrosis.

OBJECTIVE

These findings have led to the hypothesis that the gender-specific expression of Hh signaling could affect the different response of the female liver to radiation.

METHODS

Male and female mice irradiated with a single dose of 6 Gy were killed at 1 week post irradiation, and the livers were collected for biochemical analysis.

RESULTS

A greater accumulation of fatty hepatocytes and apoptotic cells was observed in irradiated female mice. Sox-9 and pancytokeratin-positive cells were expanded in the livers of irradiated female, but not male, mice. The expression of the Hh ligand, Sonic Hh, Hh receptor, Smoothened, and Hh-target gene, Gli2, showed a greater increase in the liver of radiation-treated female. The levels of epithelial-to-mesenchymal transition (EMT)-stimulating factor, transforming growth factor-β, collagen α1, and N-cadherin were upregulated, while the EMT inhibitor, bmp7, was downregulated in the damaged liver of females compared to controls. In addition, increased fibrosis was seen in the injured livers of female mice. No significant changes in Hh expression and EMT were detected in the irradiated male mice.

CONCLUSION

These results demonstrated that the increased expression of Hh signaling contributed to the different repair process in the irradiated female mice by promoting proliferation of progenitor and EMT process.

Protective effects of l-glutamine on the bladder wall of rats submitted to pelvic radiation

Radiotherapy is often used to treat prostate tumors, but the normal bladder is usually adversely affected. Using an animal model of pelvic radiation, we investigated whether glutamine nutritional supplementation can prevent radiation-induced damage to the bladder, especially in its more superficial layers. Male rats aged 3-4 months were divided into groups of 8 animals each: controls, which consisted intact animals; radiated-only rats, which were sacrificed 7 (R7) or 15 (R15) days after a radiation session (10Gy aimed at the pelvico-abdominal region); and radiated rats receiving l-glutamine supplementation (0.65g/kg body weight/day), which were sacrificed 7 (RG7) or 15 (RG15) days after the radiation session. Cells and blood vessels in the vesical lamina propria, as well as the urothelium, were then measured using histological methods. The effects of radiation were evaluated by comparing controls vs. either R7 or R15, while a protective effect of glutamine was assessed by comparing R7 vs. RG7 and R15 vs. RG15. The results showed that, in R7, epithelial thickness, epithelial cell density, and cell density in the lamina propria were not significantly affected. However, density of blood vessels in R7 was reduced by 48% (p<0.05) and this alteration was mostly prevented by glutamine (p<0.02). In R15, density of blood vessels in the lamina propria was not significantly modified. However, epithelial thickness was reduced by 25% (p<0.05) in R15, and this effect was prevented by glutamine (p<0.01). In R15, epithelial cell density was increased by 35% (p<0.02), but glutamine did not protect against this radiation-induced increase. Cell density in the lamina propria was likewise unaffected in R15. Density of mast cells in the lamina propria was markedly reduced in R7 and R15. The density was still reduced in RG7, but a higher density in RG15 suggested a glutamine-mediated recovery. Alpha-actin positive cells in the lamina propria formed a suburothelial layer and were identified as myofibroblasts. Thickness of this layer was increased in R7, but was similar to controls in RG7, while changes in R15 and RG15 were less evident. In conclusion, pelvic radiation leads to significant acute and post-acute alterations in the composition and structural features of the vesical lamina propria and epithelium. Most of these changes, however, can be prevented by glutamine nutritional supplementation. These results emphasize, therefore, the potential use of this aminoacid as a radioprotective drug.

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

PURPOSE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

ICRP publication 118: ICRP statement on tissue reactions and early and late effects of radiation in normal tissues and organs--threshold doses for tissue reactions in a radiation protection context

This report provides a review of early and late effects of radiation in normal tissues and organs with respect to radiation protection. It was instigated following a recommendation in Publication 103 (ICRP, 2007), and it provides updated estimates of 'practical' threshold doses for tissue injury defined at the level of 1% incidence. Estimates are given for morbidity and mortality endpoints in all organ systems following acute, fractionated, or chronic exposure. The organ systems comprise the haematopoietic, immune, reproductive, circulatory, respiratory, musculoskeletal, endocrine, and nervous systems; the digestive and urinary tracts; the skin; and the eye. Particular attention is paid to circulatory disease and cataracts because of recent evidence of higher incidences of injury than expected after lower doses; hence, threshold doses appear to be lower than previously considered. This is largely because of the increasing incidences with increasing times after exposure. In the context of protection, it is the threshold doses for very long follow-up times that are the most relevant for workers and the public; for example, the atomic bomb survivors with 40-50years of follow-up. Radiotherapy data generally apply for shorter follow-up times because of competing causes of death in cancer patients, and hence the risks of radiation-induced circulatory disease at those earlier times are lower. A variety of biological response modifiers have been used to help reduce late reactions in many tissues. These include antioxidants, radical scavengers, inhibitors of apoptosis, anti-inflammatory drugs, angiotensin-converting enzyme inhibitors, growth factors, and cytokines. In many cases, these give dose modification factors of 1.1-1.2, and in a few cases 1.5-2, indicating the potential for increasing threshold doses in known exposure cases. In contrast, there are agents that enhance radiation responses, notably other cytotoxic agents such as antimetabolites, alkylating agents, anti-angiogenic drugs, and antibiotics, as well as genetic and comorbidity factors. Most tissues show a sparing effect of dose fractionation, so that total doses for a given endpoint are higher if the dose is fractionated rather than when given as a single dose. However, for reactions manifesting very late after low total doses, particularly for cataracts and circulatory disease, it appears that the rate of dose delivery does not modify the low incidence. This implies that the injury in these cases and at these low dose levels is caused by single-hit irreparable-type events. For these two tissues, a threshold dose of 0.5Gy is proposed herein for practical purposes, irrespective of the rate of dose delivery, and future studies may elucidate this judgement further.

Radiation effects on cellularity, proliferation and EGFR expression in mouse bladder urothelium

This study was designed to determine changes in cell numbers, proliferation (using Ki-67) and EGFR expression in mouse bladder urothelium during the early and late radiation response. Groups of mice were irradiated with a single dose of 20 Gy and assayed 0-360 days later. Urothelial cells were counted. After immunohistochemistry, the absolute and relative numbers of Ki-67(+) and EGFR(+) cells were analyzed. Radiation exposure resulted in a decrease in total urothelial cell numbers to 49% by day 31, with restoration of cellularity by day 180. In contrast, at day 360, an increase in total cell number (143%) was seen. Slightly increased Ki-67 expression was found at days 120 and 180 after treatment, followed by a pronounced elevation at days 240 and 360. Compared to controls, higher EGFR expression was detected up to day 360 after irradiation. A positive correlation was found between total urothelial cells numbers and Ki-67 as well as EGFR expression. Radiation exposure results in an increased urothelial expression of EGFR that precedes urothelial restoration, indicating a contribution of the EGF/EGFR system to urothelial proliferation and differentiation. Further studies are needed to evaluate the impact of EGFR inhibition on radiation effects in the urinary bladder.

Effect of recombinant human keratinocyte growth factor (rHuKGF, Palifermin) on radiation-induced mouse urinary bladder dysfunction

PURPOSE

To determine the effect of Palifermin (rHuKGF) on acute and late radiation effects in mouse urinary bladder.

METHODS AND MATERIALS

Graded radiation doses were applied on day 0. Single subcutaneous injections of Palifermin (15 mg/kg) were given on day -2 or day +2. Changes in bladder function (i.e., a reduction in bladder volume by >or=50% of the individual preirradiation value) were assessed by cystometry.

RESULTS

Early changes in mouse bladder after irradiation occur in two phases. In the first early phase, a single injection of Palifermin on day -2 increased the ED(50) (dose associated with a positive bladder response in 50% of the mice) from 20.0 +/- 3.3 Gy to 27.1 +/- 6.9 Gy (p < .0051). Palifermin given on day +2 was not beneficial. No significant effects of Palifermin were seen in the second early phase. However, Palifermin administration before, but not after, irradiation, also modified late radiation effects, with an ED50 of 22.2 +/- 4.8 Gy compared with 16.2 +/- 4.9 Gy in control animals (p < .0187).

CONCLUSIONS

Initial early functional changes in the mouse urinary bladder after irradiation as well as late effects can be significantly reduced by a single administration of Palifermin before irradiation.