Effects Of TLR4 Knockout On Immune Cells And Adipokines In Mouse Visceral Adipose Tissue

BackgroundToll-like receptors（Toll-like receptors,TLRs）are a major class of pattern recognition receptors,TLR now been found in a mammal 13 species.TLR4 is the earliest and most studied TLR,mainly distributed on the membranes of monocytes,macrophages,NK cells,and adipocytes.TLR4 binds to ligands to produce and release pro-inflammatory cytokines via the NF-kB signaling pathway.Therefore,TLR4 plays an important role in the body’s growth and immune function.Adipose tissue is an important tissue and organ involved in lipid metabolism.Recent studies suggest that saturated fatty acids in foods can be used as ligands of TLR4 to participate in the relevant signaling pathways for TLR4 activation.What happens if the body’s TLR4 gene is lost will affect adipose tissue?No literature has been reported.This study was to investigate the effect of loss of TLR4 gene on immune cells and adipokines in visceral adipose tissue of mice.ObjectiveTo investigate the effects of TLR4 knockout on the major immune cells/inflammatory factors and adipokines in mouse visceral adipose tissue.Methods1.Male C57BL/6 mice and TLR4 knockout mice were randomly selected and routinely reared at ages of 20 weeks.Mice were sacrificed by cervical dislocation,and spleen cells and epididymal adipose tissue cells were isolated.Flow cytometry was used to detect the expression of F4/80,CD11b,CD11c,CD3,CD4,and CD8 molecules.2.The epididymal adipose tissue of wild-type C57BL/6 mice and TLR4 knockout mice was taken and q-PCR was used to detect the expression of IL-6,HMGB1,TNF-α,adiponectin and resistin in adipose tissue of the epididymis.Results1.Compared with wild-type C57BL/6 mice,the proportion of M1 macrophages in spleen and epididymal adipose tissue increased in TLR4^-/-mice（P<0.05）,and the proportion of M2macrophages decreased（P<0.05）.This trend was more pronounced in epididymal adipose tissue,with M1/M2 in the epididymal adipose tissue being more pronounced than in the spleen.2.Compared with wild-type C57BL/6 mice,the proportion of CD4⁺T cells in epididymal adipose tissue of TLR4^-/-mice decreased（P<0.05）,but the proportion of CD8+T cells increased（P<0.05）;Compared with wild-type C57BL/6 mice,the expression of IL-6,HMGB1 and resistin in epididymal adipose tissue of TLR4^-/-mice was significantly increased（P<0.05）;and TNF-αand adiponectin were expressed.Significantly decreased（P<0.05）.ConclusionTLR4 knockout can lead to disorders of visceral adipose tissue adipokines and immune cells.