[The effects of low-dose Co-60 irradiation on the course of aseptic arthritis in a rabbit knee joint]

Exploring low-dose radiotherapy to overcome radio-immunotherapy resistance

Immune checkpoint inhibitors (ICIs) have revolutionized the current treatment landscape for cancer, yet the response rates of ICIs remain unmet. Synergistic with immunotherapy, low-dose radiotherapy (LDRT) has been demonstrated to activate anti-tumor immunity - a transition from traditional radiation therapy geared toward local radical treatment to a type of immunological adjuvant. As such, studies utilizing LDRT to enhance the efficacy of immunotherapy have been increasing preclinically and clinically. This paper reviews the recent strategies of using LDRT to overcome the resistance of ICIs, as well as providing potential opportunities in cancer treatment. Despite the potential of LDRT in immunotherapy is recognized, the mechanisms behind this form of treatment remain largely elusive. Thus, we reviewed history, mechanisms and challenges associated with this form of treatment, as well as different modes of its application, to provide relatively accurate practice standards for LDRT as a sensitizing treatment when combined with immunotherapy or radio-immunotherapy.

The role of radiation treatment in the management of inflammatory musculoskeletal conditions: a revisit

Inflammatory musculoskeletal conditions are a common group of diseases among the elderly, worldwide. They are characterized by articular degenerative changes accompanied with often debilitating pain. Treatments often involve life-long analgesic therapy or joint replacement in extreme cases. The aim of this current review is to look at the role of radiation treatment with the hope of further study into the effectiveness of radiation treatment in reducing pain, eliminate or reduce the need for life-long analgesic therapy and thereby avoiding the analgesics’ side effects. Extensive literature search was done on PubMed and other available data base and the findings are presented and discussed. Literature showed that many countries in Europe, especially Germany use radiation routinely for the treatment of many degenerative disorders including osteoarthritis with good results and few side effects. A pilot study is therefore recommended with a view to establish the effectiveness or otherwise of this treatment method in patients.

Low-dose γ-radiation inhibits IL-1β-induced dedifferentiation and inflammation of articular chondrocytes via blockage of catenin signaling

Although low-dose radiation (LDR) regulates a wide range of biological processes, limited information is available on the effects of LDR on the chondrocyte phenotype. Here, we found that LDR, at doses of 0.5–2 centiGray (cGy), inhibited interleukin (IL)-1β-induced chondrocyte destruction without causing side effects, such as cell death and senescence. IL-1β treatment induced an increase in the expression of α-, β-, and γ-catenin proteins in chondrocytes via Akt signaling, thereby promoting dedifferentiation through catenin-dependent suppression of Sox-9 transcription factor expression and induction of inflammation through activation of the NF-κB pathway. Notably, LDR blocked cartilage disorders by inhibiting IL-1β-induced catenin signaling and subsequent catenin-dependent suppression of the Sox-9 pathway and activation of the NF-κB pathway, without directly altering catenin expression. LDR also inhibited chondrocyte destruction through the catenin pathway induced by epidermal growth factor, phorbol 12-myristate 13-acetate, and retinoic acid. Collectively, these results identify the molecular mechanisms by which LDR suppresses pathophysiological processes and establish LDR as a potentially valuable therapeutic tool for patients with cytokine- or soluble factors-mediated cartilage disorders.

Efficacy of low-dose radiotherapy in painful gonarthritis: experiences from a retrospective East German bicenter study

PURPOSE

To evaluate the efficacy of low-dose radiotherapy in painful gonarthritis.

METHODS

We assessed the medical records of 1037 patients with painful gonarthritis who had undergone low-dose radiotherapy between 1981 and 2008. The subjective patient perception of the response to irradiation as graded immediately or up to two months after the completion of a radiotherapy series was evaluated and correlated with age, gender, radiological grading and the duration of symptoms before radiotherapy. Moreover, we performed a mail survey to obtain additional long-term follow-up information and received one hundred and six evaluable questionnaires.

RESULTS

We assessed 1659 series of radiotherapy in 1037 patients. In 79.3% of the cases the patients experienced a slight, marked or complete pain relief immediately or up to two months after the completion of radiotherapy. Gender, age and the duration of pain before radiotherapy did not have a significant influence on the response to irradiation. In contrast, severe signs of osteoarthritis were associated with more effective pain relief. In more than 50% of the patients who reported a positive response to irradiation a sustained period of symptomatic improvement was observed.

CONCLUSIONS

Our results confirm that low-dose radiotherapy is an effective treatment for painful osteoarthritis of the knee. In contrast to an earlier retrospective study, severe signs of osteoarthritis constituted a positive prognostic factor for the response to irradiation. A randomized trial is urgently required to compare radiotherapy with other treatment modalities.

Immunomodulatory properties and molecular effects in inflammatory diseases of low-dose x-irradiation

Inflammatory diseases are the result of complex and pathologically unbalanced multicellular interactions. For decades, low-dose X-irradiation therapy (LD-RT) has been clinically documented to exert an anti-inflammatory effect on benign diseases and chronic degenerative disorders. By contrast, experimental studies to confirm the effectiveness and to reveal underlying cellular and molecular mechanisms are still at their early stages. During the last decade, however, the modulation of a multitude of immunological processes by LD-RT has been explored in vitro and in vivo. These include leukocyte/endothelial cell adhesion, adhesion molecule and cytokine/chemokine expression, apoptosis induction, and mononuclear/polymorphonuclear cell metabolism and activity. Interestingly, these mechanisms display comparable dose dependences and dose-effect relationships with a maximum effect in the range between 0.3 and 0.7 Gy, already empirically identified to be most effective in the clinical routine. This review summarizes data and models exploring the mechanisms underlying the immunomodulatory properties of LD-RT that may serve as a prerequisite for further systematic analyses to optimize low-dose irradiation procedures in future clinical practice.

Anti-inflammatory effects of low-dose radiotherapy. Indications, dose, and radiobiological mechanisms involved

Low-dose radiotherapy (LD-RT) has been used for several benign diseases, including arthrodegenerative and inflammatory pathologies. Despite its effectiveness in clinical practice, little is known about the mechanisms through which LD-RT modulates the various phases of the inflammatory response and about the optimal dose fractionation. The objective of this review is to deepen knowledge about the most effective LD-RT treatment schedule and radiobiological mechanisms underlying the anti-inflammatory effects of LD-RT in various in vitro experiments, in vivo studies, and clinical studies.

Radio-immunological mechanisms of anti-inflammatory treatment: is there a way from the past into the future?

The anti-inflammatory efficiency of low-dose radiotherapy (LD-RT) for degenerative joint disorders was demonstrated over decades but had no explanation on a cellular or molecular level. As inflammatory diseases are the results of complex and pathologically unbalanced cellular and molecular interactions more recent in-vivo and in-vitro data will be discussed for possible explanation of the mechanism underlying ant-inflammatory LD-RT.2.

Low‐dose radiotherapy (LD‐RT) and the modulation of iNOS expression in adjuvant‐induced arthritis in rats

PURPOSE

Low-dose radiotherapy (LD-RT) of arthritic joints applied during the peak of the acute inflammatory response improves the clinical and histomorphological development of adjuvant arthritis. The study was undertaken to investigate the cellular composition of the inflammatory infiltrate and the expression of the pro-inflammatory and anti-inflammatory enzymes, inducible nitric oxide synthase (iNOS), cyclo-oxygenase 2 (COX-2) and haem-oxygenase 1 (HO-1), in response to LD-RT.

MATERIALS AND METHODS

Adjuvant arthritis in female Lewis rats was induced by intradermal injection of heat-inactivated mycobacterium tuberculosis on day 0. Both arthritic hind paws were sham irradiated (group 1) or X-irradiated with either 5 x 1.0 Gy (group 2) or 5 x 0.5 Gy (group 3) from days 15 to 19 after induction (15 animals/group). On days 21 (n=12 joints/group) and 30 (n=18 joints/group), cryostat sections were analysed histologically and immunohistologically after specific staining for macrophages, iNOS, COX-2 and HO-1.

RESULTS

A total of 5 x 1.0 Gy or 5 x 0.5 Gy led to a significant reduction of clinical symptoms from days 21 to 29, and a highly significant reduction of cartilage and bone destruction on day 30. Macrophage-positive areas could be detected continuously throughout the periarticular infiltrate, and were slightly reduced after LD-RT on days 21 and 30. This reduction was more pronounced after 5 x 1.0 Gy. Following LD-RT, the iNOS score was reduced by about 45-50% on days 21 (p<0.05) and 30 (p<0.001). In contrast, the HO-1 score was increased by about 50% on days 21 (p=0.08) and 30 (p=0.03).

CONCLUSIONS

The clinically and histologically observed prevention of the progression of adjuvant arthritis after LD-RT given during the peak of the acute inflammatory response and the reduction of cartilage and bone destruction in the chronic phase appears to be related to the modulation of iNOS activity by low X-ray doses.

Radiation treatment of acute inflammation in mice

PURPOSE

Low-dose radiotherapy (RT) has often been used effectively for the treatment of a variety of benign diseases, particularly those with acute inflammatory features. Here we report findings on radiation treatment of acute inflammation using a murine carrageenin air pouch model.

MATERIALS AND METHODS

Air pouches raised on the dorsal surface of mice were injected with lambda carrageenin and were irradiated 6 h later with doses ranging from 0-5 Gy. Treatment success was evaluated at various times thereafter by volume of exudate and number of inflammatory cells, and levels of inflammation-related cytokines tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1beta) and transforming growth factor beta-1 (TGFbeta-1), and expression of inducible nitric oxide synthase (iNOS), heme oxygenase-1 (HO-1), cyclooxygenase-2 (COX-2) and inducible heat shock protein 70 (HSP70) as determined by enzyme-linked immunosorbent assay (ELISA) and Western blotting, respectively.

RESULTS

Crude inflammatory parameters such as the amount of exudates and number of inflammatory cells remained largely unaffected by radiation or were even a slightly and transiently increased. However, the expression of iNOS was attenuated by radiation concomitant with an increase in the levels of HO-1 and HSP70. Cytokine levels varied with the radiation dose and the time point.

CONCLUSIONS

Ionizing radiation, even at low doses, functionally modulates inflammatory cells. Our findings indicate possible mechanisms as to how low-dose radiation may exert anti-inflammatory effects and provide the first evidence that heat shock proteins may be involved in this response.

Long-term results of radiotherapy for periarthritis of the shoulder: a retrospective evaluation

Background

To evaluate retrospectively the results of radiotherapy for periarthritis of the shoulder

Methods

In 1983–2004, 141 patients were treated, all had attended at least one follow-up examination. 19% had had pain for several weeks, 66% for months and 14% for years. Shoulder motility was impaired in 137/140 patients. Nearly all patients had taken oral analgesics, 81% had undergone physiotherapy, five patients had been operated on, and six had been irradiated. Radiotherapy was applied using regular anterior-posterior opposing portals and Co-60 gamma rays or 4 MV photons. 89% of the patients received a total dose of 6 Gy (dose/fraction of 1 Gy twice weekly, the others had total doses ranging from 4 to 8 Gy. The patients and the referring doctors were given written questionnaires in order to obtain long-term results. The mean duration of follow-up was 6.9 years [0–20 years].

Results

During the first follow-up examination at the end of radiotherapy 56% of the patients reported pain relief and improvement of motility. After in median 4.5 months the values were 69 and 89%, after 3.9 years 73% and 73%, respectively. There were virtually no side effects. In the questionnaires, 69% of the patients reported pain relief directly after radiotherapy, 31% up to 12 weeks after radiotherapy. 56% of the patients stated that pain relief had lasted for "years", in further 12% at least for "months".

Conclusion

Low-dose radiotherapy for periarthropathy of the shoulder was highly effective and yielded long-lasting improvement of pain and motility without side effects.

Radiobiological mechanisms in inflammatory diseases of low-dose radiation therapy

PURPOSE

Whereas X-irradiation with high doses is established to exert pro-inflammatory effects, low-dose radiotherapy (LD-RT) with single fractions below 1.0 Gy and a total dose below 12 Gy is clinically well known to exert anti-inflammatory and analgesic effects on several inflammatory diseases and painful degenerative disorders. Experimental studies to confirm the effectiveness, the empirical dose and fractionation schemes, and the underlying radiobiological mechanisms are still fragmentary.

METHOD

The anti-inflammatory efficiency of LD-RT was confirmed in several experimental in vitro and in vivo models.

RESULTS

In vitro studies revealed a variety of mechanisms related to the anti-inflammatory effect, in particular the modulation of cytokine and adhesion molecule expression on activated endothelial cells and leukocytes, and of nitric oxide (NO) production and oxidative burst in activated macrophages and native granulocytes.

CONCLUSION

Inflammatory diseases are the result of complex and pathologically unbalanced multicellular interactions. It is, therefore, reasonable to assume that further molecular pathways and cellular components contribute to the anti-inflammatory effect of LD-RT. This review discusses data and models revealing aspects of the mechanisms underlying the anti-inflammation induced by low doses of X-irradiation and may serve as a basis for systematic analyses, necessary to optimize LD-RT in clinical practice.

Radiobiological mechanisms of anti-inflammatory radiotherapy

Radiotherapy with total doses of < or =6 Gy has been given as very effective and low risk treatment of painful degenerative joint diseases and other inflammatory processes. Recent radiobiological experiments in vitro and in vivo identified mechanisms which may be related to these anti-inflammatory radiation effects, in particular functional modulation of the adhesion of white blood cells to activated endothelial cells and modulation of the induction of nitric oxide synthase in activated macrophages.