Accumulation of Glycosaminoglycans in Radiation-induced Muscular Fibrosis

Esophageal stenosis as an independent factor of poor prognosis in patients with ESCC treated with definitive chemoradiotherapy

Aim: To evaluate the clinical outcome and elucidate the prognostic factors in patients with esophageal squamous cell carcinoma (ESCC) treated with definitive chemoradiotherapy (CRT). Patients: Data for patients newly diagnosed with ESCC receiving definitive CRT at our institution between 2012 and 2018 were retrospectively reviewed. Results: A total of 201 patients were included. Severe stenosis after radiotherapy was an independent factor relevant to prognosis. Maximal esophageal wall thickness, short-term responses, severe stenosis at diagnosis and a high neutrophil-to-lymphocyte ratio were independent risk factors for the occurrence of severe stenosis after radiotherapy. Conclusion: Severe stenosis after radiotherapy is a useful predictive indicator in patients with ESCC receiving definitive CRT. Further studies are needed to verify these findings.

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.

Pathophysiology of Radiation-Induced Dysphagia in Head and Neck Cancer

Oncologic treatments, such as curative radiotherapy and chemoradiation, for head and neck cancer can cause long-term swallowing impairments (dysphagia) that negatively impact quality of life. Radiation-induced dysphagia comprised a broad spectrum of structural, mechanical, and neurologic deficits. An understanding of the biomolecular effects of radiation on the time course of wound healing and underlying morphological tissue responses that precede radiation damage will improve options available for dysphagia treatment. The goal of this review is to discuss the pathophysiology of radiation-induced injury and elucidate areas that need further exploration.

Radiation-induced camptocormia and dropped head syndrome: Review and case report of radiation-induced movement disorders

BACKGROUND

In recent years, camptocormia and dropped head syndrome (DHS) have gained attention as particular forms of movement disorders. Camptocormia presents with involuntary forward flexion of the thoracolumbar spine that typically increases during walking or standing and may severely impede walking ability. DHS is characterized by weakness of the neck extensors and a consecutive inability to extend the neck; in severe cases the head is fixed in a "chin to chest position." Many diseases may underlie these conditions, and there have been some reports about radiation-induced camptocormia and DHS.

METHODS

A PubMed search with the keywords "camptocormia," "dropped head syndrome," "radiation-induced myopathy," "radiation-induced neuropathy," and "radiation-induced movement disorder" was carried out to better characterize radiation-induced movement disorders and the radiation techniques involved. In addition, the case of a patient developing camptocormia 23 years after radiation therapy of a non-Hodgkin's lymphoma of the abdomen is described.

RESULTS

In total, nine case series of radiation-induced DHS (n = 45 patients) and-including our case-three case reports (n = 3 patients) about radiogenic camptocormia were retrieved. Most cases (40/45 patients) occurred less than 15 years after radiotherapy involving extended fields for Hodgkin's disease.

CONCLUSION

The use of wide radiation fields including many spinal segments with paraspinal muscles may lead to radiation-induced movement disorders. If paraspinal muscles and the thoracolumbar spine are involved, the clinical presentation can be that of camptocormia. DHS may result if there is involvement of the cervical spine. To prevent these disorders, sparing of the spine and paraspinal muscles is desirable.

Characterization and regulation of mechanical loading-induced compensatory muscle hypertrophy

In mammalian systems, skeletal muscle exists in a dynamic state that monitors and regulates the physiological investment in muscle size to meet the current level of functional demand. This review attempts to consolidate current knowledge concerning development of the compensatory hypertrophy that occurs in response to a sustained increase in the mechanical loading of skeletal muscle. Topics covered include: defining and measuring compensatory hypertrophy, experimental models, loading stimulus parameters, acute responses to increased loading, hyperplasia, myofiber-type adaptations, the involvement of satellite cells, mRNA translational control, mechanotransduction, and endocrinology. The authors conclude with their impressions of current knowledge gaps in the field that are ripe for future study.

Hyaluronan expressed by the hematopoietic microenvironment is required for bone marrow hematopoiesis

The contribution of hyaluronan (HA) to the regulatory network of the hematopoietic microenvironment was studied using knock-out mice of three hyaluronan synthase genes (Has1, Has2, and Has3). The number of hematopoietic progenitors was decreased in bone marrow and increased in extramedullary sites of Prx1-Cre;Has2(flox/flox);Has1(-/-);Has3(-/-) triple knock-out (tKO) mice as compared with wild type (WT) and Has1(-/-);Has3(-/-) double knock-out (dKO) mice. In line with this observation, decreased hematopoietic activity was observed in long term bone marrow cultures (LTBMC) from tKO mice, whereas the formation of the adherent layer and generation of hematopoietic cells in WT and dKO cultures was not different. 4-Methylumbelliferone (4MU) was used to pharmacologically inhibit the production of HA in LTBMC. Treatment with 4MU inhibited HA synthesis, decreased expression of HAS2 and HAS3, and eliminated hematopoiesis in LTBMC, and this effect was alleviated by the addition of exogenous HA. Exogenous HA also augmented the cell motility in LTBMC, which correlated with the HA-stimulated production of chemokines and growth factors. Conditioned media from HA-induced LTBMC enhanced the chemotaxis of hematopoietic stem/progenitor cells (HSPC) in response to SDF-1. Exposure of endothelial cells to 4MU decreased their ability to support HSPC rolling and adhesion. In addition, migration of transplanted HSPC into the marrow of 4MU-pretreated mice was lower than in untreated mice. Collectively, the results suggest that HA depletion reduces the ability of the microenvironment to support HSPC, and confirm a role for HA as a necessary regulatory element in the structure of the hematopoietic microenvironment.

Long-term functional outcome of brachytherapy for carcinoma of the mobile tongue: focus on the atrophic change of irradiated tongue

OBJECTIVE

To assess tongue atrophy and long-term functional outcome of mobile tongue cancer patients after interstitial radiotherapy.

METHODS

Of 493 patients whose squamous cell carcinoma of the mobile tongue had been treated with low dose rate brachytherapy, there were 57 patients evaluated between July 2002 and April 2004 whose tongue had not been modified by surgical procedures and who had no primary recurrence. The median time from treatment to evaluation was 96 months (range: 9-214 months). Almost all of the patients belonged to the early stage tongue cancer (T1/T2/T3/T4=30:24:3:0), and all had received interstitial radiotherapy with a single-plane implant. To evaluate the deformity of the tongue, we used a grading system that classified the atrophic changes of the tongue into four categories (G0-G3).

RESULTS

Thirty-nine patients (70%) showed mild tongue hemiatrophy (G1 or G2) in the irradiated side. However, no patients showed severe atrophy where the tongue cannot be made to protrude beyond the incisors (G3). The length of time after brachytherapy was >72 months and the age of the patients at brachytherapy had the same statistical significance (P=0.0366). As for functional outcome, understandability of speech and a normal diet were preserved for almost all patients.

CONCLUSION

The progression of atrophic change in the irradiated tongue occurred over a long term after brachytherapy. However, most patients could maintain their activities of daily life without severe restriction.

Quantification of masticatory muscle atrophy after high-dose radiotherapy

PURPOSE

To determine the rate of change in the cross-sectional area of the masticatory muscles after radiotherapy.

METHODS AND MATERIALS

Eligible patients had undergone unilateral radiotherapy between 1993 and 2000 and had a baseline CT scan, a comparable follow-up CT scan a minimum of 1 year later, and no recurrence of cancer. Fourteen patients had their CT series scanned into digital image files. Two anatomically selected CT slices were bisected by the midline sagittal plane and stored under randomly assigned file names. Three observers measured the masseter and medial pterygoid areas on two occasions.

RESULTS

The intraobserver reliability of the muscle area measurements was 96.3% for the masseter and 97.1% for the medial pterygoid. The interobserver reliability of the muscle area measurements was 96.7% for the masseter and 96.3% for the medial pterygoid. On the treated side, the muscles received a median dose of 56 Gy (range 47-63) in 2.0-0.4-Gy fractions. With a median follow-up of 2.9 years (range 1-7.6), mixed-effects regression analysis demonstrated a significant area of reduction of -0.17 cm(2)/y (p = 0.0001) for the masseter and -0.13 cm(2)/y (p = 0.001) for the medial pterygoid. The controlled rate of muscle atrophy was 3.9%/y (95% confidence interval 1.4-6.4) for the masseter and 2.3%/y (95% confidence interval -0.6 to 5.1) for the medial pterygoid.

CONCLUSION

Standard therapeutic radiation doses appear to cause significant masticatory muscle atrophy.

The radiotherapeutic injury--a complex 'wound'

Radiotherapeutic normal tissue injury can be viewed as two simultaneously ongoing and interacting processes. The first has many features in common with the healing of traumatic wounds. The second is a set of transient or permanent alterations of cellular and extracellular components within the irradiated volume. In contrast to physical trauma, fractionated radiation therapy produces a series of repeated insults to tissues that undergo significant changes during the course of radiotherapy. Normal tissue responses are also influenced by rate of dose accumulation and other factors that relate to the radiation therapy schedule. This article reviews the principles of organised normal tissue responses during and after radiation therapy, the effect of radiation therapy on these responses, as well as some of the mechanisms underlying the development of recognisable injury. Important clinical implications relevant to these processes are also discussed.

Striking regression of subcutaneous fibrosis induced by high doses of gamma rays using a combination of pentoxifylline and alpha-tocopherol: an experimental study

PURPOSE

To establish a successful treatment of subcutaneous fibrosis developing after high doses of gamma rays, suitable for use in clinical practice.

METHODS AND MATERIALS

We used an animal model of acute localized gamma irradiation simulating accidental overexposure in humans. Three groups of 5 Large White pigs were irradiated using a collimated 192Ir source to deliver a single dose of 160 Gy onto the skin surface (100%) of the outer side of the thigh. A well-defined block of necrosis developed within a few weeks which had healed after 26 weeks to leave a block of subcutaneous fibrosis involving skin and skeletal muscle. One experimental group of 5 pigs was dosed orally for 26 weeks starting 26 weeks after irradiation with 1600 mg/120 kg body weight of pentoxifylline (PTX) included in the reconstituted food during its fabrication, and another group of 5 was dosed orally for the same period with a daily dose of 1600 mg/120 kg body weight of PTX combined with 2000 IU/120 kg body weight of alpha-tocopherol. Five irradiated control pigs were given normal food only. Animals were assessed for changes in the density of the palpated fibrotic block and in the dimensions of the projected cutaneous surface. Depth of scar tissue was determined by ultrasound. Physical and sonographic findings were confirmed by autopsy 26 weeks after treatment started. The density, length, width, and depth of the block of fibrotic scar tissue, and the areas and volume of its projected cutaneous surface, were compared before treatment, 6 and 13 weeks thereafter, and at 26 weeks.

RESULTS

The experimental animals exhibited no change in behavior and no abnormal clinical or anatomic signs. No modifications were observed in the block of fibrotic scar tissue of pigs dosed with PTX alone. However, significant softening and shrinking of this block were noted in the pigs dosed with PTX + alpha-tocopherol 13 weeks after treatment started and at autopsy, when mean regression was approximately 30% for length, approximately 50% for width and depth, and approximately 70% for area and volume. Histologic examination showed completely normal muscle and subcutaneous tissue surrounding the residual scar tissue. The 50% decrease in the linear dimensions of the scar tissue, were comparable to the results obtained in our previous clinical studies, and were highly significant compared to the clinical and autopsy results for the controls. Histologic examination of the residual scar tissue revealed tissue which was more homogenous and less cellular and inflammatory than in control and PTX-dosed pigs. The tissular and cellular immunolocalization of tumor necrosis factor alpha (TNFalpha) was similar in the residual fibrotic tissues of all three groups of pigs, whereas the immunostaining of transforming growth factor beta-1(TGFbeta-1) diminished much more in the residual fibrotic scar tissue of the PTX + alpha-tocopherol-dosed pigs than in the two other groups.

CONCLUSIONS

The present results showed a striking regression of the subcutaneous fibrotic scar tissue that develops as a consequence of high doses of gamma rays.

Successful treatment of radiation-induced fibrosis using Cu/Zn-SOD and Mn-SOD: an experimental study

PURPOSE

To establish how far liposomal copper/zinc superoxide dismutase (Cu/Zn-SOD) and manganese superoxide dismutase (Mn-SOD), respectively, reduce radiation-induced fibrosis (RIF), using a well-characterized pig model of RIF permitting the design of a controlled laboratory experiment.

METHODS AND MATERIALS

In this model of acute localized gamma irradiation simulating accidental overexposure in humans, three groups of five large white pigs were irradiated using a collimated 192Ir source to deliver a single dose of 160 Gy onto the skin surface (100%) of the outer side of the thigh. A well-defined block of subcutaneous fibrosis involving skin and skeletal muscle developed 6 months after irradiation. One experimental group of five pigs was then injected i.m. with 10 mg/10 kg b.wt. of Cu/Zn-SOD, twice a week for 3 weeks, and another experimental group of five was injected with 10 mg/10 kg b.wt. of Mn-SOD, three times a week for 3 weeks. Five irradiated control pigs were injected with physiological serum. Animals were assessed for changes in the density of the palpated fibrotic block and in the dimensions of the projected cutaneous surface. Block depth was determined by ultrasound. Physical and sonographic findings were confirmed by autopsy 12-14 weeks after completing SOD injections. The density, length, width, and depth of the fibrotic block, and the areas and volume of its projected cutaneous surface were compared before treatment, 1, 3, and 6 weeks thereafter, and at autopsy, 12-14 weeks after treatment ended.

RESULTS

The experimental animals exhibited no change in behavior and no abnormal clinical or anatomic signs. Whether they were given Cu/Zn- or Mn-SOD, significant and roughly equivalent softening and shrinking of the fibrotic block were noted in all treated animals between the first week after treatment ended and autopsy, when mean regression was 45% for length and width, 30% for depth, and 70% for area and volume. Histologic examination showed completely normal muscle and subcutaneous tissue surrounding the residual scar. This replacement of scar tissue by normal tissue in experimental animals and the 50% decrease in the linear dimensions of the scar were comparable to the results obtained in previous clinical studies and highly significant compared to the clinical and autopsy results for the control animals.

CONCLUSIONS

Our results are striking and comparable to the results obtained in our previous clinical study after liposomal Cu/Zn-SOD treatment. To our knowledge, this is the first time that two agents have been shown to reverse the radiation-induced fibrotic process in experimental animals and to permit the regeneration of normal tissue in a zone of well-established postirradiation fibrosis.

Late radiation injury to muscle and peripheral nerves

Late radiation injury to muscles and peripheral nerves is infrequently observed. However, the success of radiation oncology has led to longer patient survival, providing a greater opportunity for late effects to develop, increase in severity and, possibly, impact the quality of life of the patient. In addition, when radiation therapy is combined with surgery and/or chemotherapy, the risk of late complications is likely to increase. It is clear that the incidence of complications involving muscles and nerves increases with time following radiation. The influence of volume has yet to be determined; however, an increased volume is likely to increase the risk of injury to muscles and nerves. Experimental and clinical studies have indicated that the alpha/beta ratio for muscle is approximately 4 Gy and, possibly, 2 Gy for peripheral nerve, indicating the great influence of fractionation on response of these tissues. This is of concern for intraoperative radiation therapy, and for high dose rate brachytherapy. This review of clinical and experimental data discusses the response of muscle and nerves late after radiation therapy. A grading system has been proposed and endpoints suggested.

Expression of 72-kDa gelatinase (MMP-2), collagenase (MMP-1), and tissue metalloproteinase inhibitor (TIMP) in primary pig skin fibroblast cultures derived from radiation-induced skin fibrosis

In addition to producing matrix degradation for normal tissue remodeling and repair, matrix metalloproteinases (MMPs) are also involved in various pathologic processes. MMPs and the tissue inhibitor of MMPs (TIMP) were investigated in primary cultures of pig fibroblasts from radiation-induced dermal fibrosis and compared to normal dermal fibroblasts. The free gelatinolytic, collagenolytic, and caseinolytic activities secreted into the culture medium were evaluated against specific 3H denatured collagen type I, native helical collagen, and casein alpha, respectively. The 72- and 68-kilodalton (kDa) forms of type IV collagenase were investigated by protease zymography and quantified by semi-automated image analysis. Transcription of the interstitial collagenase (MMP-1) and TIMP genes was studied by Northern hybridization analysis. Results revealed that in fibrotic fibroblasts, the amount of MMP-1 mRNA was greatly reduced to undetectable levels whereas the amount of TIMP mRNA was increased fourfold compared to controls. Functional assays using specific 3H substrates demonstrated an overall decrease in free MMP activities. Concomitantly, catheptic collagenolytic activity decreased in fibrotic fibroblast extracts compared to controls. These results indicate that in addition to accumulating large amounts of collagen, proteoglycans, and fibronectin, pig fibroblasts from radiation-induced dermal fibrosis also promote connective tissue matrix formation by repressing MMP-1 and stimulating TIMP expression at the transcriptional level, and by reducing overall free MMP and catheptic collagenolytic activities at the post-transcriptional level. In contrast, enzymography assays and automated image analysis demonstrated no significant change in the 72-kDa type IV collagenase activity of fibrotic pig skin fibroblasts. This opposite regulation of 72-kDa collagenase type IV to that of MMP-1 seems to indicate that it has a specific role in remodeling the extracellular matrix during wound healing, fibrogenesis, and angiogenesis.

Effects of gamma-irradiation on the M-CSF-promoter linked to a chloramphenicol aminoacyl transferase reporter gene expressed in a clonal murine bone marrow stromal cell line

The effects of cytokines produced by bone marrow stromal cells on closely associated hematopoietic cells constitute a major component of the physiology of the hematopoietic microenvironment. A major cytokine produced by marrow stromal cells is macrophage colony-stimulating factor (M-CSF). To determine the effect of gamma-irradiation on the M-CSF promoter in bone marrow stromal cells, we selected a clonal cell line from the C3H/HeJ mouse marrow stromal cell line D2XRII and stably transfected a reporter construct containing the murine M-CSF-promoter linked to a chloramphenicol aminoacyl transferase (CAT) gene. CAT activity was measured at serial time points after gamma-irradiation in vitro to doses between 500 and 10,000 cGy at a dose rate of 116 cGy/min. D2XRII marrow stromal cells treated with phorbol myristate acetate (40 micrograms/ml, four h), demonstrated a significant two-fold increase in CAT activity. In contrast, CAT activity measured immediately, 24 h, 72 h or 1 week after gamma-irradiation, showed no significant increase or decrease in CAT activity. An increase in CAT activity was detected 48 h after irradiation with cells that received 5,000 cGy. Thus, single fraction gamma-irradiation of plateau phase bone marrow stromal cells did not decrease M-CSF-promoter activity. These results are consistent with prior experimental data demonstrating stable levels of release of M-CSF protein following gamma-irradiation of bone marrow stromal cells and imply that the stability of transcription of the gene for this important cytokine is protected from irradiation.

Muscular fibrosis induced after pig skin irradiation with single doses of 192Ir gamma-rays

Localized irradiation of the skin and subcutaneous tissues with large single doses of gamma-rays can induce delayed effects characterized by fibrosis which invades the irradiated tissues. In this study the depth of penetration of muscle fibrosis was measured in the pig 30 weeks after irradiation of the skin surface with single doses of 192Ir gamma-rays of 16-256 Gy. Irradiation was directed either to the outer side of the thigh or to the back, close to the mid-dorsal line. Fibrosis only developed in irradiated muscle after doses that induced moist desquamation of the skin in the acute phase of the reaction, i.e. after skin surface doses of 48-64 Gy. In skeletal muscles, the limit of fibrotic expansion was reached at a depth dose of 14 +/- 4 Gy (+/- SD) for skin surface doses exceeding 48 Gy.