Fig. 1.

(A) TLR4 signaling pathway can be activated via GAG fragments requiring CD44 and MyD88 or through LPS, which requires MyD88, LBP, and CD14. (B) CD44 adhesion receptor (55 kDa) is a hyaluronan-binding cell surface glycoprotein involved in the initiation of GAG-induced inflammation via TLR4. Elevated CD44 expression was detected in 6-month-old MPS VI rat FLSs and articular chondrocytes, confirming the activation of TLR4 via the GAG pathway in MPS. Protein kinase C-α (PKC-α; 82 kDa) was used as a loading control.