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Selective STAT3 Inhibitor Alantolactone Ameliorates Osteoarthritis via Regulating Chondrocyte Autophagy and Cartilage
Wenbin Pei1, Xiaojian Huang1, Bowei Ni1
1Department of Orthopedics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Abstract:
Osteoarthritis (OA), which is identified by chronic pain, impacts the quality of life. Cartilage degradation and inflammation are the most relevant aspects involved in its development. Signal transducer and activator of transcription 3(STAT3), a member of the STATs protein family, is associated with inflammation. Alantolactone (ALT), a sesquiterpene lactone compound, can selectively suppress the phosphorylation of STAT3. However, the pharmacological effect of ALT on OA is still imprecise. In this study, IL-1β (10 ng/ml) was applied to cartilage chondrocytes, which were treated with different concentrations of Alantolactone for 24 h. The expression of inducible nitric oxide synthase (iNOS), cyclooxygenase-2(COX2), matrix metalloproteinases (MMPs) and thrombospondin motifs-5 (ADAMTS5) were detected by western blot. Protein expression of Collagen Ⅱ was observed by western blot, safranin O staining and immunofluorescence. Manifestation of autophagy related proteins such as autophagy-related gene-5 (ATG5), P62, LC3Ⅱ/Ⅰ and PI3K/AKT/mTOR-related signaling molecules were measured by western blot and autophagic flux monitored by confocal microscopy. Expression of STAT3 and NF-κB-related signaling molecules were evaluated by western blot and immunofluorescence. In vivo, 2 mg/kg ALT or equal bulk of vehicle was engaged in the destabilization of medial meniscus (DMM) mouse models by intra-articular injection, the degree of cartilage destruction was classified by Safranin O/Fast green staining. Our findings reported that the enhance of inflammatory factors containing iNOS, COX2, MMPs and ADAMTS5 induced by IL-1β could be ameliorated by ALT. Additionally, the diminish of Collagen Ⅱ and autophagy which was stimulated by IL-1β could be alleviated by ALT. Mechanistically, STAT3, NF-κB and PI3K/AKT/mTOR signal pathways might be involved in the effect of ALT on IL-1β-induced mouse chondrocytes. In vivo, ALT protected cartilage in the DMM mouse model. Overall, this study illustrated that ALT attenuated IL-1β-induced inflammatory responses, relieved cartilage degeneration and promoted impaired autophagy via restraining of STAT3 and NF-κB signal pathways, implying its auspicious therapeutical effect for OA.
Insights
Alantolactone (ALT) reduces inflammation and cartilage damage in osteoarthritis (OA) by inhibiting STAT3 and NF-κB pathways. This natural compound shows therapeutic potential for OA by restoring autophagy and protecting cartilage.
Area of Science:
- Biochemistry
- Cell Biology
- Pharmacology
Background:
- Osteoarthritis (OA) is characterized by chronic pain and cartilage degradation, significantly impacting quality of life.
- Inflammation and the Signal Transducer and Activator of Transcription 3 (STAT3) pathway are key factors in OA development.
- Alantolactone (ALT), a sesquiterpene lactone, is known to suppress STAT3 phosphorylation, but its effects on OA are not fully understood.
Purpose of the Study:
- To investigate the pharmacological effects of Alantolactone (ALT) on osteoarthritis (OA) in vitro and in vivo.
- To elucidate the underlying molecular mechanisms of ALT's action, focusing on inflammatory and autophagy pathways.
- To evaluate ALT's potential as a therapeutic agent for OA.
Main Methods:
- In vitro: IL-1β-induced mouse chondrocytes were treated with ALT to assess inflammatory markers (iNOS, COX2, MMPs, ADAMTS5), Collagen II expression, and autophagy-related proteins (ATG5, P62, LC3II/I).
- Signaling pathways (STAT3, NF-κB, PI3K/AKT/mTOR) were analyzed using western blot and immunofluorescence.
- In vivo: Destabilization of the medial meniscus (DMM) mouse model was used to evaluate ALT's protective effects on cartilage via Safranin O/Fast green staining.
Main Results:
- ALT significantly ameliorated IL-1β-induced increases in inflammatory factors (iNOS, COX2, MMPs, ADAMTS5) in chondrocytes.
- ALT treatment alleviated the IL-1β-induced decrease in Collagen II expression and promoted autophagy.
- ALT administration protected cartilage in the DMM mouse model, reducing cartilage destruction.
Conclusions:
- Alantolactone (ALT) attenuates IL-1β-induced inflammatory responses and cartilage degeneration in OA models.
- ALT promotes autophagy and protects cartilage, likely through the inhibition of STAT3 and NF-κB signaling pathways.
- ALT demonstrates promising therapeutic potential for treating osteoarthritis.
