The Effect of Radiation on the Immune System in Pigs Affected by the Fukushima Daiichi Nuclear Power Plant Accident

Ayaka Kato,Yasushi Kino,Tsutomu Sekine,Manabu Fukumoto,Kei Okuda,Tomokazu Fukuda,Motoko Morimoto,Yasuyuki Abe,Emiko Isogai,Yoshikazu Kuwahara,Jin Kobayashi

doi:10.1007/978-981-13-8218-5_11

Abstract

It is extremely important to understand the mechanisms underlying the effect of radiation on animals including humans. Radiation potentially induces alterations of the immune system, which may cause serious diseases. The Fukushima Daiichi Nuclear Power Plant (FNPP) accident occurred in 2011, in which radioactive contaminants were released over a wide area. After farmers evacuated from the ex-evacuation zone set within 20-km radius from FNPP, pigs were left behind and unleashed in the zone (abandoned pigs). Their small intestine was considered to have been affected by the dietary intake of radioactive contaminants. The present study thus aimed to clarify the effect of radiation by investigating whether there is any alteration in the expression of genes encoding immune-related molecules and in morphology of the intestine of abandoned pigs. Microarray analysis revealed changes of the expression of various genes involved in inflammation and oxidative stress including IFN-γ, which is an important inflammatory cytokine, was highly elevated in abandoned pigs, and its expression level was correlated with radioactive cesium concentration in skeletal muscle. On the other hand, there were no morphological changes in the intestine. At the sampling stage of this study, only 1 year passed since the FNPP accident occurred, it would be premature to conclude that the identified alteration of gene expression was caused only by artificial radionuclides attributed to the FNPP accident. We need to continue monitoring the effect of long-term radiation exposure in living organisms in the ex-evacuation zone.

Highlights

The immune system is essential for host defense against pathogens and for regulation of physiological functions
The immune system consists of innate immunity, which mediates the initial reaction by neutrophils, macrophages and innate lymphocytes (ILCs), and adaptive immunity, which develops more slowly but produces a specific reaction against antigens by lymphocytes [1]
To identify the genes that were up- or down-regulated by radiation in the ex- evacuation zone, RNA was extracted for cDNA microarray analysis from the small intestine, which is highly sensitive to radiation [17]

Summary

Introduction

The immune system is essential for host defense against pathogens and for regulation of physiological functions. The immune cells and nonimmune cells cooperate to maintain homeostasis in the body. Their interaction is regulated by a range of biologically active substances called cytokines. A large number of cytokines have been found to play key roles in regulating immune responses and inflammation. The lymphocytes, T and B lymphocytes, are the most important immune cells for the development of appropriate and effective reactions in various situations. Inappropriate immune responses, including cytokine imbalances, contribute to the development of persistent diseases [2]. Insufficient responses result in the establishment of infection, while excessive activation of the immune system may cause chronic inflammation, which is central to the pathogenesis of various diseases [3]

Methods

Results

Conclusion