COVID-19 and low-dose radiation therapy

Low-moderate dose whole-brain γ-ray irradiation modulates the expressions of glial fibrillary acidic protein and intercellular adhesion molecule-1 in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-induced Parkinson's disease mouse model

The anti-inflammatory efficacy of radiation therapy (RT) with single fractions below 1.0 Gy has been demonstrated in Alzheimer's disease mouse models. As neuroinflammation is also a major pathological feature of Parkinson's disease (PD), RT may also be effective in PD treatment. Therefore, this study aimed to investigate the anti-inflammatory effect of low-moderate dose RT (LMDRT, 0.6 Gy/single dose, for 5 days) exposure in a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP; 30 mg/kg, intraperitoneally, for 5 consecutive days)-induced PD mouse model. Importantly, LMDRT reduced the levels of glial fibrillary acidic protein and intercellular adhesion molecule-1 (CD54) in the striatum region, which increased following MPTP administration. LMDRT also modulated inflammatory gene expression patterns in the substantia nigra region of the MPTP-treated mice. However, LMDRT had no direct effects on the severe loss of dopaminergic neurons and impaired motor behavior in the rotarod test. These results indicate that LMDRT has anti-inflammatory effects by modulating neuroinflammatory factors, including glial fibrillary acidic protein and intercellular adhesion molecule-1, but showed no behavioral improvements or neuroprotection in the MPTP-induced mouse model of PD.

The Hormesis Concept: Strengths and Shortcomings

Hormesis implies that the effects of various materials or conditions that organisms are exposed to, may not have linear dose-response characteristics but rather, can be biphasic. Thus the response to a low dose of a stressor may be the opposite to that occurring at higher doses. Such a dual response is postulated for many toxicants and physical conditions and may involve a beneficial adaptive response. Such a non-linear effect is undoubtedly present in many useful pharmacological and nutraceutical agents with can be toxic at high concentrations. This somewhat divisive topic is an area of study that should be objectively studied and not clouded by political and policy considerations. The objective of this review is to examine claims concerning those exposures where hormesis seems to exist and also those where there is no good supporting evidence. The breadth of this phenomenon and potential mechanisms underlying hormetic events are discussed together with their limitations.

Low-dose radiation therapy suppresses viral pneumonia by enhancing broad-spectrum anti-inflammatory responses via transforming growth factor-β production

Low-dose radiation therapy (LDRT) can suppress intractable inflammation, such as that in rheumatoid arthritis, and is used for treating more than 10,000 rheumatoid arthritis patients annually in Europe. Several recent clinical trials have reported that LDRT can effectively reduce the severity of coronavirus disease (COVID-19) and other cases of viral pneumonia. However, the therapeutic mechanism of LDRT remains unelucidated. Therefore, in the current study, we aimed to investigate the molecular mechanism underlying immunological alterations in influenza pneumonia after LDRT. Mice were irradiated to the whole lung 1 day post-infection. The changes in levels of inflammatory mediators (cytokines and chemokines) and immune cell populations in the bronchoalveolar lavage (BALF), lungs, and serum were examined. LDRT-treated mice displayed markedly increased survival rates and reduced lung edema and airway and vascular inflammation in the lung; however, the viral titers in the lungs were unaffected. Levels of primary inflammatory cytokines were reduced after LDRT, and transforming growth factor-β (TGF-β) levels increased significantly on day 1 following LDRT. Levels of chemokines increased from day 3 following LDRT. Additionally, M2 macrophage polarization or recruitment was increased following LDRT. We found that LDRT-induced TGF-β reduced the levels of cytokines and polarized M2 cells and blocked immune cell infiltration, including neutrophils, in BALF. LDRT-induced early TGF-β production was shown to be a key regulator involved in broad-spectrum anti-inflammatory activity in virus-infected lungs. Therefore, LDRT or TGF-β may be an alternative therapy for viral pneumonia.

How the Science of Radiation Biology Can Help Reduce the Crippling Fear of Low-level Radiation

ABSTRACT

The fear of radiation has been present almost since the discovery of radiation, but has intensified since the "dawn of the atomic age" over 75 y ago. This fear has often served as an impediment to the safe and beneficial uses of radiation and radioactive material. The underlying causes of such fear are varied, can be complex, and are often not associated with any scientific knowledge or understanding. The authors believe that a clear understanding of the current scientific knowledge and understanding of the effects of radiation exposure may be useful in helping to allay some of the fear of radiation. This manuscript attempts to (1) address several scientific questions that we believe have contributed to the fear of radiation, (2) review the data derived from research that can be used to address these questions, and (3) summarize how the results of such scientific research can be used to help address the fear of low-dose and low-dose-rate radiation. Several examples of how fear of radiation has affected public perception of radiological events are discussed, as well as a brief history of the etiology of radiation fear. Actions needed to reduce the public fear of radiation and help fulfill the full societal benefits of radiation and radioactive materials are suggested.

Low-Dose Radiotherapy for Patients with Pneumonia Due to COVID-19: A Single-Institution Prospective Study

Purpose: Results of the low-dose radiation therapy (LDRT) in patients with pneumonia due to COVID-19 has been presented. Methods: Fifteen patients received a single-fraction radiation dose of 1 Gy to the bilateral lungs due to pre-ARDS pneumonia in the course of COVID-19. Follow-up was performed on days 1, 3, 5, 7, 14 after LDRT. Results: Eleven patients (73%) were released up until day 28. Median hospitalization was 20 days; 28-day mortality was 13%. Median O2 saturation improved within 24 h after LDRT in 14/15, with median SpO2 values of 84.5% vs. 87.5% p = 0.016, respectively. At day 14 of hospitalization, 46% did not require oxygen supplementation. Significant decline in CRP and IL-6 was observed within 24 h post LDRT. No organ toxicities were noted. Conclusion: LDRT is feasible, well tolerated and may translate to early clinical recovery in patients with severe pneumonia. Further studies are needed to determine optimal candidate, time and dose of LDRT for COVID-19 patients with pneumonia.

Role of low-dose radiation in senescence and aging: A beneficial perspective

Cellular senescence refers to the permanent arrest of cell cycle caused by intrinsic and/or extrinsic stressors including oncogene activation, irradiation, DNA damage, oxidative stress, and certain cytokines (including senescence associated secretory phenotype). Cellular senescence is an important factor in aging. Accumulation of senescent cells has been implicated in the causation of various age-related organ disorders, tissue dysfunction, and chronic diseases. It is widely accepted that the biological effects triggered by low-dose radiation (LDR) are different from those caused by high-dose radiation. Experimental evidence suggests that LDR may promote growth and development, enhance longevity, induce embryo production, and delay the progression of chronic diseases. The underlying mechanisms of these effects include modulation of immune response, stimulation of hematopoietic system, antioxidative effect, reduced DNA damage and improved ability for DNA damage repair. In this review, we discuss the possible mechanisms by which LDR prevents senescence and aging from the perspectives of inhibiting cellular senescence and promoting the removal of senescent cells. We review a wide broad of evidence about the beneficial impact of LDR in senescence and aging models (including cardiovascular diseases, neurological diseases, arthritis and osteoporosis, chronic obstructive pulmonary disease and idiopathic pulmonary fibrosis) to highlight the potential value of LDR in preventing aging and age-related diseases. However, there is no consensus on the effect of LDR on human health, and several important aspects require further investigation.

Covid-19 and radiotherapy: a systematic review after 2 years of pandemic

Introduction

Following the Covid-19 pandemic spread, changes in clinical practice were necessary to limit the pandemic diffusion. Also, oncological practice has undergone changes with radiotherapy (RT) treatments playing a key role.Although several experiences have been published, the aim of this review is to summarize the current evidence after 2 years of pandemic to provide useful conclusions for clinicians.

Methods

A Pubmed/MEDLINE and Embase systematic review was conducted. The search strategy was "Covid AND Radiotherapy" and only original articles in the English language were considered.

Results

A total of 2.733 papers were obtained using the mentioned search strategy. After the complete selection process, a total of 281 papers were considered eligible for the analysis of the results.

Discussion

RT has played a key role in Covid-19 pandemic as it has proved more resilient than surgery and chemotherapy. The impact of the accelerated use of hypofractionated RT and telemedicine will make these strategies central also in the post-pandemic period.

Preliminary Approach to Implementing a COVID-19 Thoracic Radiation Therapy Program

The value of low-dose whole thoracic radiation therapy (LD-WTRT) for SARS-CoV-2 (COVID-19) pneumonia is unknown. Should ongoing clinical trials demonstrate that LD-WTRT proves effective for COVID-19 pneumonia recovery, widespread rapid implementation will be helpful globally. Our aim was to outline a pragmatic process for safe and efficient administration of LD-WTRT to patients with COVID-19 pneumonia that could be implemented successfully in a community hospital setting based on participation in the PreVent clinical trial of LD-WTRT.