The antibacterial activity of erythrocytes from Clarias fuscus associated with phagocytosis and respiratory burst generation

Zizheng Xu; Youcheng Yang; V Sarath Babu; Jiajun Chen; Feng Li; Minxuan Yang; Ningqiu Li; Jun Li; Li Lin; Zhendong Qin

doi:10.1016/j.fsi.2021.10.001

The antibacterial activity of erythrocytes from Clarias fuscus associated with phagocytosis and respiratory burst generation

Fish Shellfish Immunol. 2021 Dec:119:96-104. doi: 10.1016/j.fsi.2021.10.001. Epub 2021 Oct 3.

Authors

Zizheng Xu¹, Youcheng Yang¹, V Sarath Babu¹, Jiajun Chen¹, Feng Li¹, Minxuan Yang¹, Ningqiu Li², Jun Li³, Li Lin⁴, Zhendong Qin⁵

Affiliations

¹ Guangdong Provincial Water Environment and Aquatic Products Security Engineering Technology Research Center, Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, College of Animal Sciences and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong Province, 510222, China.
² Guangdong Provincial Water Environment and Aquatic Products Security Engineering Technology Research Center, Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, College of Animal Sciences and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong Province, 510222, China; Pearl River Fisheries Research Institute, Chinese Academy of Fishery Sciences, China.
³ Guangdong Provincial Water Environment and Aquatic Products Security Engineering Technology Research Center, Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, College of Animal Sciences and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong Province, 510222, China; School of Science and Medicine, Lake Superior State University, Sault Ste. Marie, MI, 49783, USA.
⁴ Guangdong Provincial Water Environment and Aquatic Products Security Engineering Technology Research Center, Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, College of Animal Sciences and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong Province, 510222, China. Electronic address: linli@zhku.edu.cn.
⁵ Guangdong Provincial Water Environment and Aquatic Products Security Engineering Technology Research Center, Guangzhou Key Laboratory of Aquatic Animal Diseases and Waterfowl Breeding, College of Animal Sciences and Technology, Zhongkai University of Agriculture and Engineering, Guangzhou, Guangdong Province, 510222, China. Electronic address: qinzhendongsc@163.com.

PMID: 34614395
DOI: 10.1016/j.fsi.2021.10.001

Abstract

It is widely known that red blood cells (RBCs) are responsible for respiration and the transport of gas. However, recent reports have also described the immune properties of RBCs, therefore creating new understanding for the functionality of RBCs. However, little is known about the immunological role of RBCs in bony fish. In this study, we used RBCs from Clarias fuscus as a model and demonstrate that these cells exhibited phagocytic ability with both latex beads and bacteria. Scanning electron microscopy and transmission electron microscopy provided visual confirmation of the phagocytotic process in RBCs. In addition, we used flow cytometry and fluorescence microscopy to analyse the rate of phagocytosis in RBCs. We found that RBCs exhibited stable phagocytotic ability with latex beads ranging from 0.5 to 1.0 μm in size. In response to bacterial stimulation, RBCs produced reactive oxygen species (ROS) and nitric oxide synthase (NOS), which are harmful to bacteria. RBCs also have an antioxidant system. Under conditions of oxidative stress, the expression levels of antioxidant enzymes, and particularly those of superoxide dismutase（SOD） increased significantly. Our results show that the erythrocytes of bony fish are phagocytic and also produce ROS which are toxic to bacteria. In addition, RBCs have an antioxidant system that removes excess ROS production to protect cells from oxidative damage.

Keywords: Antibacterial activity; Antioxidant enzymes; Clarias fuscus; Phagocytosis; RBCs; ROS.

MeSH terms

Animals
Anti-Bacterial Agents / pharmacology
Antioxidants*
Erythrocytes
Phagocytosis
Reactive Oxygen Species
Respiratory Burst*

Substances

Anti-Bacterial Agents
Antioxidants
Reactive Oxygen Species