Therapeutic effects of Melittin acupoint injection on rheumatoid arthritis through autophagy activation and PI3K/AKT/mTOR pathway inhibition

Weizhe Xi; Fenfang Liu; Guangen Zhong; Fen Chen; Yin Xie; Meilian Lai; Qiting He; Yiqing Lu; Jiping Zhang; Ying Chen; Luo Meng; Lu Yang

doi:10.21037/qims-2025-540

Therapeutic effects of Melittin acupoint injection on rheumatoid arthritis through autophagy activation and PI3K/AKT/mTOR pathway inhibition

Quant Imaging Med Surg. 2026 Jan 1;16(1):18. doi: 10.21037/qims-2025-540. Epub 2025 Dec 31.

Authors

Weizhe Xi^#¹, Fenfang Liu^#², Guangen Zhong^#², Fen Chen³, Yin Xie¹, Meilian Lai¹, Qiting He¹, Yiqing Lu¹, Jiping Zhang¹, Ying Chen², Luo Meng², Lu Yang^{1

2}

Affiliations

¹ College of Traditional Chinese Medicine, Southern Medical University, Guangzhou, China.
² Department of Acupuncture and Rehabilitation, Integrated Hospital of Traditional Chinese Medicine, Southern Medical University, Guangzhou, China.
³ College of Traditional Chinese Medicine, Huizhou Health Sciences Polytechnic, Huizhou, China.

^# Contributed equally.

Abstract

Background: Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease that leads to cartilage degradation and bone destruction, significantly impacting daily life. Melittin acupoint injection (MAI) is a promising traditional Chinese medicine treatment, but its molecular mechanisms are not fully understood. This study aimed to investigate the therapeutic effects of MAI on RA and elucidate its underlying mechanisms.

Methods: A collagen-induced arthritis (CIA) mouse model was established using bovine type II collagen, administered every other day for 28 days. The mice were randomly divided into a CIA model group (MO group), melittin acupoint subcutaneous injection group (ST group), melittin acupoint intramuscular injection group (IT group), and methotrexate group (MTX group), with an additional normal control group (NC group) established. Each group contained 8 mice, all of which were treated for 28 days. Therapeutic outcomes were assessed by measuring body weight, swollen joint count (SJC), arthritis index (AI), ankle circumference, and plantar thickness. Radiological and histological changes were analyzed with micro-computed tomography (CT) imaging and pathological staining. Cytokine levels were measured via enzyme-linked immunosorbent assay (ELISA), and autophagy levels were assessed using immunofluorescence staining. The phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin (PI3K/AKT/mTOR) signaling pathway and autophagy status were examined through western blot (WB) and immunofluorescence techniques.

Results: MAI significantly improved clinical symptoms in CIA mice by reducing plantar thickness, AI scores, and swollen joints (P<0.05). Histopathological analysis showed decreased inflammatory cell infiltration, synovial proliferation, and cartilage damage (P<0.01). Micro-CT and immunohistochemistry revealed reduced inflammation, bone destruction, and cartilage erosion, along with decreased tumor necrosis factor-α (TNF-α) expression (P<0.05). MAI also lowered serum levels of interleukin (IL)-1β (P<0.05), IL-17A, and TNF-α (P<0.01), while increasing IL-10 levels (P<0.05). Immunofluorescence indicated increased microtubule-associated protein 1 light chain 3 beta (LC3B) fluorescence intensity (P<0.05). WB analysis showed elevated levels of Unc-51-like autophagy activating kinase 1 (ULK1), beclin-1 (P<0.01), and microtubule-associated protein 1 light chain 3 II (LC3II) (P<0.05), and reduced phosphorylation of PI3K, AKT, and mTOR (P<0.05).

Conclusions: MAI alleviates RA symptoms by inhibiting the PI3K/AKT/mTOR pathway and promoting autophagy.

Keywords: Melittin acupoint injection (MIA); autophagy; collagen-induced arthritis (CIA); phosphoinositide 3-kinase/protein kinase B/mammalian target of rapamycin signaling pathway (PI3K/AKT/mTOR signaling pathway).