Effect of Pharmacological Blocking of TLR-4 on Osteoarthritis in Mice

Abstract

Receptors for Advanced Glycation End Products (RAGE) and Toll Like Receptor 4 (TLR-4) have been shown to play a role in the development of Osteoarthritis (OA). We have previously shown that knocking out RAGE in mice slows the disease progression in articular cartilage of the knee. The objective of this study was to determine if application of the compound TAK-242, a TLR-4 specific inhibitor, in conjunction with knocking out RAGE could further attenuate the disease. Destabilization of the medial meniscus of RAGE KO and Wild Type (WT mice) was performed, and severity of OA was qualitatively analyzed through two standardized scoring systems (Mankin and OARSI). We also performed immunohistochemistry to analyze levels of HtrA1, Mmp-13 and Tgf-β1, known biomarkers for the disease. Surprisingly, addition of the TLR blocker did not offer additional protection against OA in mice when RAGE had been knocked out, and its application to WT mice exacerbated the severity of OA. We conclude that while blockage of the RAGE pathway alone is beneficial to the attenuation of OA, hampering the TLR-4 pathway offers no protective benefits.Citation: Siebert M,

Osteoarthritis-Like Changes in Bardet–Biedl Syndrome Mutant Ciliopathy Mice (Bbs1M390R/M390R): Evidence for a Role of Primary Cilia in Cartilage Homeostasis and Regulation of Inflammation

“…Knees from wild type (WT) n = 44 ( n = 8 10–14 weeks old; n = 24 15–18 weeks old; n = 12 21+ weeks old) and Bbs1 M390R/M390R n = 61 ( n = 18 10–14 weeks old; n = 39 15–18 weeks old; n = 4 21+ weeks old) mutant mice were obtained from the laboratory of Val Sheffield at the University of Iowa. Knees were harvested and fixed in 4% paraformaldehyde prior to decalcification and embedding according to a previously reported procedure ( Spencer et al, 2015 ). Knees were serially sectioned and sections analyzed histologically after staining with Safranin O and fast green as previously reported ( Spencer et al, 2015 ).…”

“…Knees were harvested and fixed in 4% paraformaldehyde prior to decalcification and embedding according to a previously reported procedure ( Spencer et al, 2015 ). Knees were serially sectioned and sections analyzed histologically after staining with Safranin O and fast green as previously reported ( Spencer et al, 2015 ). Using a light microscope equipped with a digital camera, photographs of each knee joint were taken at 100× and 200× magnifications.…”