Protective Effects of Phellinus linteus Mycelium on the Development of Osteoarthritis after Monosodium Iodoacetate Injection

Abstract

Objective: The aim of this study was to identify the protective effects of Phellinus linteus mycelium (PLM) and its possible mechanisms in a model of monosodium iodoacetate- (MIA-) induced osteoarthritis (OA).

Methods: Intra-articular injection of MIA was injected to 50 μL with 80 mg/mL using a 0.3 mL insulin syringe into the right knee joint. Changes in hindpaw weight-bearing distribution between the right (osteoarthritic) and left (contralateral control) legs were used as an index of joint discomfort. PLM (50, 100, and 200 mg/kg body weight) was orally administered once daily for 14 days from day 7 after MIA treatment. And then, various factors associated with inflammatory response and cartilage degeneration in cartilage tissues detected by western blotting.

Results: PLM treatment showed a concentration-dependent elevation in change in hindpaw weight-bearing distribution (HWBD). PLM200 demonstrated the capacity to significantly increase HWBD, indicating that the change in weight-bearing distribution means the reduction of spontaneous pain. Our results indicate that PLM suppressed the inflammatory factors via NF-κB signaling pathway induced by p38 phosporlyation. Moreover, PLM200 exhibited a significant reduction of ROS produced by the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. PLM100 and PLM200 inhibited the levels of matrix metalloproteinase (MMP)-1, one of proteinase that degrades extracellular matrix (ECM).

Conclusions: Taken together, our results indicated that PLM has a strong chondroprotective effect through the suppression both ROS production and inflammation.

Figure 1

Change in Hindpaw weight-bearing distribution. Values are the mean ± SEM (n = 7). Nor: normal rats; Con: MIA-induced osteoarthritis rats; GLM200: MIA-induced osteoarthritis rats administrated with green-lipped mussel 200 mg/kg body weight; PLM50: MIA-induced osteoarthritis rats administrated with PLM 50 mg/kg body weight; PLM100: MIA-induced osteoarthritis rats administrated with PLM 100 mg/kg body weight; PLM200: MIA-induced osteoarthritis rats administrated with PLM 200 mg/kg body weight. Significance: ^#P < 0.05, ^##P < 0.01 vs. normal rat values. ∗After 2 weeks, the decreased HWBD was significantly increased at GLM200 and PLM200 groups (P < 0.05).

Figure 2

NADPH oxidases: NOX4, p47^phox, and p22^phox in cartilage tissues. Values are the mean ± SEM (n = 6). Nor: normal rats; Con; MIA-induced osteoarthritis rats; GLM200: MIA-induced osteoarthritis rats administrated with green-lipped mussel 200 mg/kg body weight; PLM50: MIA-induced osteoarthritis rats administrated with PLM 50 mg/kg body weight; PLM100: MIA-induced osteoarthritis rats administrated with PLM 100 mg/kg body weight; PLM200: MIA-induced osteoarthritis rats administrated with PLM 200 mg/kg body weight. Significance: ^#P< 0.05, ^###P < 0.001 vs. normal rat values and ^∗P < 0.05, ^∗∗P < 0.01 vs. MIA control rat values.

Figure 3

p-p38 and NF-κBp65 protein expressions in cartilage tissues. Values are the mean ± SEM (n = 6). Nor: normal rats; Con: MIA-induced osteoarthritis rats; GLM200: MIA-induced osteoarthritis rats administrated with green-lipped mussel 200 mg/kg body weight; PLM50: MIA-induced osteoarthritis rats administrated with PLM 50 mg/kg body weight; PLM100: MIA-induced osteoarthritis rats administrated with PLM 100 mg/kg body weight; PLM200: MIA-induced osteoarthritis rats administrated with PLM 200 mg/kg body weight. Significance: ^##P < 0.01 vs. normal rat values and ^∗P < 0.05, ^∗∗∗P < 0.001 vs. MIA control rat values.

Figure 4

iNOS, and COX-2, TNF-α, IL-6, and IL-1β protein expressions in cartilage tissues. Values are the mean ± SEM (n = 6). Nor: normal rats; Con: MIA-induced osteoarthritis rats; GLM200: MIA-induced osteoarthritis rats administrated with green-lipped mussel 200 mg/kg body weight; PLM50: MIA-induced osteoarthritis rats administrated with PLM 50 mg/kg body weight; PLM100: MIA-induced osteoarthritis rats administrated with PLM 100 mg/kg body weight; PLM200: MIA-induced osteoarthritis rats administrated with PLM 200 mg/kg body weight. Significance: ^##P < 0.01: ^###P < 0.001 vs. normal rat values and ^∗P < 0.05: ^∗∗P < 0.01: ^∗∗∗P < 0.001 vs. MIA control rat values.

Figure 5

MMP-1 and TIMP-1 protein expressions in cartilage tissues. Values are the mean ± SEM (n = 6). Nor: normal rats; Con: MIA-induced osteoarthritis rats; GLM200: MIA-induced osteoarthritis rats administrated with green-lipped mussel 200 mg/kg body weight; PLM50: MIA-induced osteoarthritis rats administrated with PLM 50 mg/kg body weight; PLM100: MIA-induced osteoarthritis rats administrated with PLM 100 mg/kg body weight; PLM200: MIA-induced osteoarthritis rats administrated with PLM 200 mg/kg body weight. Significance: ^#P< 0.05 vs. normal rat values and ^∗P < 0.05, ^∗∗P < 0.01 vs. MIA control rat values.

Figure 6

Catalase and GPx-1/2 protein expressions in cartilage tissues. Values are the mean ± SEM (n = 6). Nor: normal rats; Con: MIA-induced osteoarthritis rats; GLM200: MIA-induced osteoarthritis rats administrated with green-lipped mussel 200 mg/kg body weight; PLM50: MIA-induced osteoarthritis rats administrated with PLM 50 mg/kg body weight; PLM100: MIA-induced osteoarthritis rats administrated with PLM 100 mg/kg body weight; PLM200: MIA-induced osteoarthritis rats administrated with PLM 200 mg/kg body weight. Significance: ^##P < 0.01 vs. normal rat values and ^∗P < 0.05 vs. MIA control rat values.

Figure 7

Possible mechanism of Phellinus linteus mycelium (PLM) in MIA-induced osteoarthritis rats.