A mouse model of human TLR4 D299G/T399I SNPs reveals mechanisms of altered LPS and pathogen responses

• DOI: 10.1084/jem.20200675
• Publication Date: 2021-01-21T18:53:55Z
• Authors: Katharina Richard; Kurt H. Piepenbrink; Kari Ann Shirey; Archana Gopalakri...; Shreeram Nallar; Daniel J. Prantner; Darren J. Perkins; Wendy Lai; Alexandra Vlk; Vladimir Y. Toshc...; Chiguang Feng; Rachel Fanaroff; Andrei E. Medvedev; Jorge C.G. Blanco; Stefanie N. Vogel
• Keywords: Lipopolysaccharides; Male; 0303 health sciences; 610; Genetics and Genomics; Polymorphism, Single Nucleotide; Article; 3. Good health; Toll-Like Receptor 4; Disease Models, Animal; Mice; 03 medical and health sciences; Medicine and Health Sciences; Animals; Humans; Female; Genetic Predisposition to Disease; Dietetics and Clinical Nutrition; Food Science; Signal Transduction

Two cosegregating single-nucleotide polymorphisms (SNPs) in human TLR4, an A896G transition at SNP rs4986790 (D299G) and a C1196T transition at SNP rs4986791 (T399I), have been associated with LPS hyporesponsiveness and differential susceptibility to many infectious or inflammatory diseases. However, many studies failed to confirm these associations, and transfection experiments resulted in conflicting conclusions about the impact of these SNPs on TLR4 signaling. Using advanced protein modeling from crystallographic data of human and murine TLR4, we identified homologous substitutions of these SNPs in murine Tlr4, engineered a knock-in strain expressing the D298G and N397I TLR4 SNPs homozygously, and characterized in vivo and in vitro responses to TLR4 ligands and infections in which TLR4 is implicated. Our data provide new insights into cellular and molecular mechanisms by which these SNPs decrease the TLR4 signaling efficiency and offer an experimental approach to confirm or refute human data possibly confounded by variables unrelated to the direct effects of the SNPs on TLR4 functionality.