TLR7 Deficiency Leads to TLR8 Compensative Regulation of Immune Response against JEV in Mice.

Muhammad Awais,Chong Wang,Min Cui,Ke Wang,Zhen F Fu,Kunlun Wang,Nan Zhang,Wenjie Qian,Xianwu Lin,Ling Zhao

doi:10.3389/fimmu.2017.00160

Muhammad Awais, Chong Wang + Show 8 more

Open Access

https://doi.org/10.3389/fimmu.2017.00160

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Abstract

Japanese encephalitis virus (JEV) is a highly fatal pathogen to human beings. Toll-like receptor 7 (TLR7) plays a role as the first host defense against most single-stranded RNA flaviviruses. This study aims to investigate the role of TLR7 in inducing adaptive immune response in mice against JEV. In vitro and in vivo studies were conducted to examine the expression of toll-like receptors (TLRs) in mice. After JEV infection, physical parameters of mice (survival rate and body weight) were evaluated, and organs or cells were collected for further analysis. The expression of TLR7 was increased significantly as compare to other TLR molecules post-JEV infection. The expression of CD80, CD86, and CD273 on bone marrow-derived dendritic cells was increased significantly in TLR7−/− mice. Furthermore, viral load was also increased significantly in TLR7−/− mice as compare to C57BL/6 mice. But there was no significant difference among survival rate and body weight in TLR7−/− mice as compare to C57BL/6. Interestingly, we also found that TLR8 was upregulated in TLR7−/− mice. The study concluded that TLR8 was upregulated in TLR7-deficient mice, and it might play a compensatory role in the immune response in TLR7−/− mice.

Highlights

Japanese encephalitis virus (JEV), a single-stranded RNA virus, belongs to the family Flaviviridae that causes approximately 50,000 cases of encephalitis each year in human [1]
The JEV-P3 inoculated mice were monitored for the expression of two types of toll-like receptors (TLRs) (TLR7 and TLR8) using Quantitative reverse-transcription polymerase chain reaction (qRT-PCR)
To further confirm the increase in Toll-like receptor 7 (TLR7) expression following JEV infection, bone marrow-derived dendritic cells (bmDCs) were introduced by JEV-P3 for infection on day 11 post-culture

Summary

Introduction

Japanese encephalitis virus (JEV), a single-stranded RNA (ssRNA) virus, belongs to the family Flaviviridae that causes approximately 50,000 cases of encephalitis each year in human [1]. Within the CNS, JEV causes infection and directly kills the neurons [6]. Isolated bone marrow cells were plated in 12-well cell culture plates (LabServ®, Fisher Scientific, China) at a density of 2 × 106 cells/ml in DC media [RPMI 1640 supplemented with 10% FBS (Gibco, Grand Island, NY, USA), 100 μg/ml streptomycin, 100 Ul/ ml penicillin, and 10 ng/ml of rmGM-CSF and IL-4]. The incubation of these plates was performed at 37°C along with 5% CO2 in the incubator.

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