Low dose ionizing radiation effects on the immune system

Abstract

Ionizing radiation interacts with the immune system in many ways with a multiplicity that mirrors the complexity of the immune system itself: namely the need to maintain a delicate balance between different compartments, cells and soluble factors that work collectively to protect, maintain, and restore tissue function in the face of severe challenges including radiation damage. The cytotoxic effects of high dose radiation are less relevant after low dose exposure, where subtle quantitative and functional effects predominate that may go unnoticed until late after exposure or after a second challenge reveals or exacerbates the effects. For example, low doses may permanently alter immune fitness and therefore accelerate immune senescence and pave the way for a wide spectrum of possible pathophysiological events, including early-onset of age-related degenerative disorders and cancer. By contrast, the so called low dose radiation therapy displays beneficial, anti-inflammatory and pain relieving properties in chronic inflammatory and degenerative diseases. In this review, epidemiological, clinical and experimental data regarding the effects of low-dose radiation on the homeostasis and functional integrity of immune cells will be discussed, as will be the role of immune-mediated mechanisms in the systemic manifestation of localized exposures such as inflammatory reactions. The central conclusion is that ionizing radiation fundamentally and durably reshapes the immune system. Further, the importance of discovery of immunological pathways for modifying radiation resilience amongst other research directions in this field is implied.

Perturbed transcriptional profiles after chronic low dose rate radiation in mice

“…It should be kept in mind that the gene expression profiles observed may be an indirect effect of biological response in other tissues due to the whole-body exposure regime. The liver acts as a surveillance and response hub for the whole body by regulating systemic metabolism and maintaining homeostasis after external stimulus, particularly related to inflammatory responses and vascular damage [ 69 , 70 ].…”

Low-Dose Radiation Therapy for COVID-19: A Systematic Review

“…Emory University Hospital used 1.5 Gy, and Ameri et al tried both 0.5 Gy and 1.0 Gy. Interestingly, a paper published recently in Environment International [42] clearly indicates that while doses <1 Gy have anti-inflammatory effects, doses >1 Gy have proinflammatory effects and cause fibrosis, as illustrated in Figure 4. Thus, the doses used in the clinical trials such as the study conducted by Emory University Hospital were possibly unjustified.…”

“…Some of the most important immune-and inflammation-related processes that develop after low-, intermediate-, and high-dose irradiation. (Reproduced from[42]).…”

Microbeam Radiotherapy—A Novel Therapeutic Approach to Overcome Radioresistance and Enhance Anti-Tumour Response in Melanoma

“…A review of Haikerwal et al [ 54 ] comparing the immune effects of low- and high-dose radiation indicates that low-dose irradiation (less or equal to 2 Gy) induces DNA damage response (DDR), vascular normalization, and anti-inflammatory immune responses. The effects of low-dose radiation on the immune system may be subtle and may go unnoticed until long after exposure; these effects were comprehensively reviewed recently by Lumniczky et al [ 65 ]. Delivery of high doses of radiation increases tumour antigen release, enhancing antigen presentation and T cell infiltration [ 58 , 66 ].…”