Anti-inflammatory effects of low-dose radiotherapy

Abstract

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.

Low-dose Whole-lung Irradiation for COVID-19 Pneumonia: Short Course Results

“…Suppression of cytokine storm can potentially reduce the morbidity and mortality of COVID-19 [6]. Experimental studies have demonstrated the anti-in ammatory effect of low dose radiotherapy (LD-RT) by modulating the function of a variety of in ammatory cells, including endothelial cells, polymorphonuclear leukocytes, and macrophages [7][8][9][10][11][12]. Being such, LD-RT is considered as an opportunity to block the deadly cytokine storm and save the patients' lives.…”

Treatment of folliculitis decalvans using intensity-modulated radiation via tomotherapy

“…Owing to the sensitivity of scalp hair to radiation, in comparison with hair elsewhere on the body [13,22], and the benign nature of this disease, we decided to deliver a low radiation fraction dose (1 Gy). An additional anti-inflammatory effect of LD-IR that may result from radiation-induced depletion of inflammatory cells, including T lymphocytes and neutrophils, has been demonstrated in various experimental and clinical studies [10][11][12]. Other mechanisms, such as a decreased adhesion molecule expression and induction of apoptosis in the inflammatory cells, have also been hypothesized to reduce inflammation [10,12].…”

“…An additional anti-inflammatory effect of LD-IR that may result from radiation-induced depletion of inflammatory cells, including T lymphocytes and neutrophils, has been demonstrated in various experimental and clinical studies [10][11][12]. Other mechanisms, such as a decreased adhesion molecule expression and induction of apoptosis in the inflammatory cells, have also been hypothesized to reduce inflammation [10,12]. The effective total dose used in this study (11 Gy at 1 Gy per fraction using 6-MV photons) is nearly equivalent to the effective dose used by Smith et al (4.4 Gy single-dose radiotherapy using 50 kV).…”

“…Low doses of ionizing radiation (LD-IR) with single fractions ≤ 1.0 Gy and a total dose between 3 and 12 Gy is clinically well known to demonstrate anti-inflammatory and analgesic effects [10][11][12]. In addition, RT in higher doses (> 5-14 Gy) can sterilize the stem cells of hair follicles [13] that prove to be one etiological trigger of FD, resulting in subsequent permanent hair loss to achieve the desired effect.…”

Alteration of Cytokine Profiles in Uranium Miners Exposed to Long-Term Low Dose Ionizing Radiation

“…Inflammatory cytokines IL-1 β and TNF- α releases were reduced in peritoneal macrophages of Balb/c mice responding to exposure of 0.5 or 0.7 Gy of ionizing irradiation (X-ray) [27]. Meanwhile, low/moderate doses (0.5 Gy or 1.0 Gy) exposure is clinically used to treat benign inflammatory diseases and is therefore capable of downregulating inflammation [28, 29]. However, in our study, it seems to suggest that inflammatory responses occurred after long-term exposure to low dose ionizing radiation and the mechanism between them is an area of current research.…”