3.3 TLR8 localizes in lysosomes mediating innate immune
responses during chondrocyte injury.
Previous studies have shown that TLRs may have different subcellular
distribution in different cells. TLR8 in the immune system is mainly
located in the cytoplasmic endosomes, while its location in cartilage
organelles remains unclear. In order to determine the expression
distribution of TLR8 in chondrocytes, the co-labeling of TLR8 with
lysosomal marker LAMP, endoplasmic reticulum marker Calnexin, and
endosomal marker EEA1 was detected by the double-target
immunofluorescence method, respectively. The results showed that TLR8
was mainly co-labeled with the lysosomal marker LAMP (Fig.3A) and the
endosomal marker EEA1(Fig.3C) in rabbit chondrocytes with impact knee
joint injury, but less co labeled with the endoplasmic reticulum marker
calnexin(Fig.3B).Therefore, we concluded that TLR8 was mainly expressed
in lysosomes and endosomes, and there was no intracellular metastasis of
TLR8 after chondrocyte injury.