Effect of Aloe Vera Polypeptide Fraction for Bone Repair in Adjuvant-Induced Arthritic Rats

Yang Chenhui, Qingling Liu, Zhiheng Guo and Zemin Jiang

Background and Objective: Osteoarthritis (OA) is a degenerative, debilitative, multifactorial illness affecting the knee joints of millions of people globally. The peptide/polypeptide fraction from Aloe Vera (AV-PP) has shown anti-inflammatory potential by inhibiting inflammatory cytokines. To evaluate the efficacy and potential mechanism of action of AV-PP against bone healing during surgically induced bone damage in a rat model of Adjuvant-Induced Arthritis (AIA). Materials and Methods: A bone fracture was created in adjuvant-induced arthritis rats using a surgical drill in the anterolateral wall of the lateral condyle of the femur. Then rats were treated with either distilled water or alendronate (3.0 mg kg^–1) or AV-PP (0.25, 0.5 and 1.0 mg kg^–1) for the next 28 days. Results: AIA-induced increased paw volume and spleen weight was effectively (p<0.05) reduced by AV-PP (0.5 and 1.0 mg kg^–1) treatment. The elevated levels of synovial TNF-α, IL-1β, IL-6 and IL-17 and diminished levels of IL-4 and IL-10 were distinctly (p<0.05) restored by AV-PP treatment. Bone injury-induced up-regulated synovial RANKL and osteocalcin, whereas down-regulated OPG and Runx2 mRNA expressions were prominently (p<0.05) inhibited by AV-PP treatment. Histopathology findings of the tibiotarsal joint showed administration of AV-PP effectively (p<0.05) reduced bone inflammation and improved bone healing. Conclusion: AV-PP showed efficacy against surgically induced bone damage in a rat model of adjuvant-induced arthritis by inhibiting RANKL/OPG signalling pathway, activating osteocalcin and balancing inflammatory cytokine levels in AIA rats.

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