Loss of TLR4 in Mouse Müller cells inhibits both MyD88-dependent
and –independent signaling

Abstract

Purpose : To investigate whether the loss of TLR4 in Müller cells alters MyD88-dependent or MyD88-independent signaling in retinal Müller cells.

Methods : TLR4 floxed mice (B6(Cg)-Tlr4^tm1.1Karp/J mice) and PDGFRa-Cre (C57BL/6-Tg(Pdgfra-cre)1Clc/J ) mice were purchased from Jackson Laboratories and cross bred to generate conditional knockout mice in which TLR4 is eliminated in Müller cells. TLR4 expression in Müller cells were examined by immunofluorenscence with confocal microscope. Changes in protein levels of TLR4, MyD88, TIR domain-containing adaptor inducing IFN-b (TRIF), tumor necrosis factor receptor-associated factor 6 (TRAF6), interleukin 1 receptor associated kinase 1 (IRAK1), interferon regulator factor 3 (IRF3), IL-1b and TNFa were analyzed by Western blot or ELISA.

Results : TLR4 levels were almost absent in Müller cells in TLR4-PDGFRa-Cre mice by using double staining with glutamine synthase compared to TLR4 floxed mice. Protein levels of TLR4, MyD88, IRAK1, TRAF6, TRIF and IRF3 were decreased in whole retinal lysates from TLR4-PDGFRa-Cre mice compare to TLR4 floxed mice. Both TNFa and IL1b were also reduced in TLR4 conditional KO mice.

Conclusions : We developed and confirmed successful knockdown of TLR4 in retinal Müller cells. We also found that loss of TLR4 caused a reduction in both MyD88-dependent and –independent signaling in whole retinal lysates from Müller cell specific TLR4 knockout out mice.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.