[Radiation-induced superficial fibrosis and TGF-alpha 1]

Molecular biological mechanisms of radiotherapy-induced skin injury occurrence and treatment

Radiotherapy-Induced Skin Injury (RISI) is radiation damage to normal skin tissue that primarily occurs during tumor Radiotherapy and occupational exposure. The risk of RISI is high due to the fact that the skin is not only the first body organ that ionizing radiation comes into contact with, but it is also highly sensitive to it, especially the basal cell layer and capillaries. Typical clinical manifestations of RISI include erythema, dry desquamation, moist desquamation, and ulcers, which have been established to significantly impact patient care and cancer treatment. Notably, our current understanding of RISI's pathological mechanisms and signaling pathways is inadequate, and no standard treatments have been established. Radiation-induced oxidative stress, inflammatory responses, fibrosis, apoptosis, and cellular senescence are among the known mechanisms that interact and promote disease progression. Additionally, radiation can damage all cellular components and induce genetic and epigenetic changes, which play a crucial role in the occurrence and progression of skin injury. A deeper understanding of these mechanisms and pathways is crucial for exploring the potential therapeutic targets for RISI. Therefore, in this review, we summarize the key mechanisms and potential treatment methods for RISI, offering a reference for future research and development of treatment strategies.

[Radiation induced brachial plexopathy: Diagnosis, risk factors, principles of care]

Radiation plexitis, also known as radiation-induced brachial neuropathy is a rare toxicity following axillary, breast, cervical or thoracic radiotherapy, first described in 1966 by Stoll and Andrew. Although improvements in radiotherapy techniques have greatly reduced its risk over the past seventy years, its severe form remains a dreaded complication that is difficult to manage in patients with increased life expectancy. This article summarizes the epidemiological elements, risk factors, diagnostic methods, doses and constraints to be respected in radiotherapy and the treatment strategies of radiation plexitis.

The effect of interferon gamma on conventional fractionated radiation-induced damage and fibrosis in the pelvic tissue of rabbits

We aim to investigate the effect of interferon gamma (IFN-γ) on conventional fractionated radiation–induced damage and fibrosis in ureter and colorectal mucosa. Fifty-two rabbits were randomly divided into three groups comprising a conventional radiation group, an IFN-γ group, and a control group. X-rays were used to irradiate the pelvic tissues of the rabbits in the IFN-γ and conventional radiation groups. Five days after radiation exposure, the rabbits in the IFN-γ group were administered 250,000 U/kg IFN-γ intramuscularly once a week for 5 weeks. The rabbits in the conventional radiation group received 5.0 mL/kg saline. The rabbits were sacrificed at 4, 8, 12, and 16 weeks postradiation, and the rectal and ureteral tissues within the radiation areas were collected. The results showed that the morphology of rectal and ureteral tissues was changed by X-ray radiation. The degree of damage at 4, 8, and 12 weeks, but not at 16 weeks, postradiation was significantly different between the IFN-γ and conventional radiation groups. The expression of transforming growth factor beta 1 mRNA in the ureter and colorectal mucosa of the IFN-γ group was significantly lower than that in the conventional radiation group at 4, 8, 12, and 16 weeks postradiation, but it was still higher than that in the control group. There were significant differences in the expression of collagen III among the three groups. IFN-γ can inhibit the radiation-induced upregulation of transforming growth factor beta 1 mRNA and collagen III protein in the ureter and colorectal mucosa and attenuate radiation-induced damage and fibrosis.

Induction of MiR-21 by Stereotactic Body Radiotherapy Contributes to the Pulmonary Fibrotic Response

Radiation-induced lung fibrosis, the most serious effect of lung cancer radiotherapy on normal tissue, remains a major technical obstacle to the broader application of radiotherapy to patients with lung cancer. This study describes the use of an image-guided irradiation system in mice mimicking stereotactic body radiotherapy (SBRT) to examine the molecular features of chronic fibrotic response after radiation injury. MicroRNA (miR) array analysis of injured pulmonary tissue identified a set of miRs whose expression was significantly increased in damaged lung tissue. In particular, miR-21 expression was increased at the radiation injury site, concurrent with collagen deposition. Although the inhibition of miR-21 by its specific inhibitor anti-miR-21 only marginally affected endothelial-mesenchymal transition (EndMT) in lung endothelial cells, this inhibition significantly reduced collagen synthesis in lung fibroblasts. Furthermore, ectopic expression of miR-21 was sufficient to promote a fibrotic response in lung fibroblasts, enhancing Smad2 phosphorylation concurrent with Smad7 downregulation. These findings indicate that the induction of miR-21 expression is responsible for fibrotic responses observed in mesenchymal cells at the injury site through the potentiation of TGF-β signaling. Local targeting of miR-21 at the injured area could have potential therapeutic utility in mitigating radiation-induced lung fibrosis.

Long-term alterations of cytokines and growth factors expression in irradiated tissues and relation with histological severity scoring

Purpose

Beside its efficacy in cancer treatment, radiotherapy induces degeneration of healthy tissues within the irradiated area. The aim of this study was to analyze the variations of proinflammatory (IL-1α, IL-2, IL-6, TNF-α, IFN-γ), profibrotic (TGF-β1), proangiogneic (VEGF) and stem cell mobilizing (GM-CSF) cytokines and growth factors in an animal model of radiation-induced tissue degeneration.

Materials and Methods

24 rats were irradiated unilaterally on the hindlimb at a monodose of 30 Gy. Six weeks (n = 8), 6 months (n = 8) and 1 year (n = 8) after irradiation the mediators expression in skin and muscle were analyzed using Western blot and the Bio-Plex® protein array (BPA) technology. Additional histological severity for fibrosis, inflammation, vascularity and cellularity alterations scoring was defined from histology and immnunohistochemistry analyses.

Results

A significant increase of histological severity scoring was found in irradiated tissue. Skin tissues were more radio-sensitive than muscle. A high level of TGF-β1 expression was found throughout the study and a significant relation was evidenced between TGF-β1 expression and fibrosis scoring. Irradiated tissue showed a chronic inflammation (IL-2 and TNF-α significantly increased). Moreover a persistent expression of GM-CSF and VEGF was found in all irradiated tissues. The vascular score was related to TGF-β1 expression and the cellular alterations score was significantly related with the level of IL-2, VEGF and GM-CSF.

Conclusion

The results achieved in the present study underline the complexity and multiplicity of radio-induced alterations of cytokine network. It offers many perspectives of development, for the comprehension of the mechanisms of late injuries or for the histological and molecular evaluation of the mode of action and the efficacy of rehabilitation techniques.

Feasibility of treating irradiated bone with intramedullary delivered autologous mesenchymal stem cells

Background. We aimed to explore (i) the short-term retention of intramedullary implanted mesenchymal stem cells BMSCs and (ii) their impact on the bone blood flow and metabolism in a rat model of hindlimb irradiation. Methods. Three months after 30 Gy irradiation, fourteen animals were referred into 2 groups: a sham-operated group (n = 6) and a treated group (n = 8) in which ¹¹¹In-labelled BMSCs (2 × 10⁶ cells) were injected in irradiated tibias. Bone blood flow and metabolism were assessed by serial ^99mTc-HDP scintigraphy and 1-wk cell retention by recordings of ^99mTc/¹¹¹In activities. Results. The amount of intramedullary implanted BMSCs was of 70% at 2 H, 40% at 48 H, and 38% at 168 H. Bone blood flow and bone metabolism were significantly increased during the first week after cell transplantation, but these effects were found to reduce at 2-mo followup. Conclusion. Short-term cell retention produced concomitant enhancement in irradiated bone blood flow and metabolism.

[Reirradiation of normal tissues: preclinical radiobiological data]

Reirradiation represent an unfrequent particular clinical situation. The risk/benefit ratio assessment must be taken into account, considering both clinical and dosimetric aspects. There is a relatively limited amount of preclinical data available to date and clinicians should cautiously perform reirradiations in selected indications. This review summarizes the experimental data available on reirradiation of normal tissues, the consequences on early and late toxicities as well as the intrinsic limitations of these models.

Curcumin protects against radiation-induced acute and chronic cutaneous toxicity in mice and decreases mRNA expression of inflammatory and fibrogenic cytokines

PURPOSE

To determine whether curcumin ameliorates acute and chronic radiation skin toxicity and to examine the expression of inflammatory cytokines (interleukin [IL]-1, IL-6, IL-18, IL-1Ra, tumor necrosis factor [TNF]-alpha, and lymphotoxin-beta) or fibrogenic cytokines (transforming growth factor [TGF]-beta) during the same acute and chronic phases.

METHODS AND MATERIALS

Curcumin was given intragastrically or intraperitoneally to C3H/HeN mice either: 5 days before radiation; 5 days after radiation; or both 5 days before and 5 days after radiation. The cutaneous damage was assessed at 15-21 days (acute) and 90 days (chronic) after a single 50 Gy radiation dose was given to the hind leg. Skin and muscle tissues were collected for measurement of cytokine mRNA.

RESULTS

Curcumin, administered before or after radiation, markedly reduced acute and chronic skin toxicity in mice (p < 0.05). Additionally, curcumin significantly decreased mRNA expression of early responding cytokines (IL-1 IL-6, IL-18, TNF-alpha, and lymphotoxin-beta) and the fibrogenic cytokine, TGF-beta, in cutaneous tissues at 21 days postradiation.

CONCLUSION

Curcumin has a protective effect on radiation-induced cutaneous damage in mice, which is characterized by a downregulation of both inflammatory and fibrogenic cytokines in irradiated skin and muscle, particularly in the early phase after radiation. These results may provide the molecular basis for the application of curcumin in clinical radiation therapy.

Treatment of Radiation-Induced Fibrosis of the Face with Manual Compression Therapy

Radiation-induced fibrosis (RIF) is an uncommon complication of radiation therapy. RIF most often occurs in the extremities; it is rare in the head and neck. Only a few medical treatments for RIF are available, and they have been mediocre at best. We describe a case of RIF of the face that was treated successfully with a nonmedical modality: manual compression therapy.

Delayed effects of accidental cutaneous radiation exposure: fifteen years of follow-up after the Chernobyl accident

BACKGROUND

During the Chernobyl accident in 1986, 237 individuals were identified as having the most severe exposure to ionizing radiation. In the period between 1998 and 2000, 99 long term survivors out of this group were reassessed for radiation-induced cutaneous lesions.

OBJECTIVE

To identify sequelae of accidental cutaneous irradiation.

METHODS

Detailed dermatologic examinations, including biopsies of suspicious cutaneous lesions for histopathologic examination and 20 MHz sonography, were performed in all patients.

RESULTS

Twenty-two of the 99 patients displayed radiation-induced cutaneous lesions. Epidermal atrophy, telangiectases, and pigment alterations were present in all these individuals. Keratotic lesions were found in 14 patients. Cutaneous fibrosis was documented in 8 individuals by the use of 20 MHz sonography, while a radiation ulcer was found in 5. In one patient, two basal cell carcinomas were found.

CONCLUSION

The life-long follow-up of irradiated persons is of great importance in order to identify cutaneous neoplasms at an early treatable stage.

ESTRO Breur Gold Medal Award Lecture 2001: irradiation accidents-- lessons for oncology?

Considering the number of radioactive sources in use all over the world (both in industry and medicine) irradiation accidents are exceedingly rare, as demonstrated by the main databases registering such cases: UNSCEAR, IAEA, REAC/TS (Oak Ridge, USA), the German group in Ulm and the Paris Institut Curie. The precise causes of most accidents have been openly analyzed, allowing to reduce the risk of subsequent identical accidental exposures. In addition, a rapid retrospective overview shows that positive lessons could be drawn from such accidents: 1)Lessons for patient management: one should keep in mind that the first ever allogeneic bone marrow transplantations were performed in 1958, on scientists from Yugoslavia who had been severely irradiated in a nuclear Research laboratory. Apart from what was learned from such accidents for the management of severe aplasia, the treatment of superficial accidental exposures has also benefited radiotherapy patients in certain specific situations. 2) Lessons for technology: the efforts to improve safety in nuclear plants are well known; the (successful) efforts to reduce the once-elevated risks when changing the therapeutic Cobalt 60 sources are less well known. Today, most irradiation accidents (by far) are related to misuse or loss of radioactive sources from industrial radiography sets. However, here again, various technological improvements significantly reduced the risks. 3) Lessons for radiobiology: the need for more and more sophisticated biological dosimetry has led to studies allowing better understanding of the short- and long-term effects of radiation on human cells. Analyses of samples taken in areas which were heavily accidentally irradiated also helped to identify, in particular, the cardinal role of TGF beta and TNF alpha in the development of fibrosis and necrosis after irradiation. 4) Lessons for prevention of accidents in radiotherapy: only three large-scale accidents involving external radiotherapy have been registered in the last decade, but deciphering the cause(s) of such problems clearly participated in the setting of demanding Quality Assurance programmes and strict national and international recommendations. Such open circulation of the information about these (fortunately rare) accidents appears to be one of the ways to improve Quality Assurance in Radiotherapy.

Latent-TGF-beta: an overview

The latency associated with the transforming growth factor-betas (TGF-betas) was discovered in 1984. Since the two publications on this subject in that year, there has been on average over sixty reports in which latency was the dominant theme for each of the past 10 years, proof enough of the interest in this field of growth factor research. As the mature 25 kD forms of the TGF-betas are required for them to exert their many, diverse biological effects, it was inevitable that an explanation of the structure and of the activation of the latent complexes be sought. This overview provides a description of these essential points. Now that it has been clearly shown that dysregulation of particular components of the TGF-beta signalling pathway is implicated in many human diseases, the activation of the latent TGF-beta complexes has taken on added importance. Technical improvements enable the distinction of active and latent TGF-beta proteins in vivo and have started to reveal anomalies in the control of activation in relation to various pathological situations.