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.