Cistanche deserticola Y.C.Ma protects rats against osteoporotic osteoarthritis by inhibiting the phosphatidylinositol 3-kinase/serine-threonine protein kinase B/hypoxia-inducible factor 1 alpha signaling pathway

Ethnopharmacological relevance: Osteoporotic osteoarthritis (OPOA) is characterized by kidney deficiency, muscle debility, and lumbar weakness, which is align closely with "deficiency in kidney yang" in Traditional Chinese Medicine (TCM) theory. As a tonic TCM herb, Cistanche deserticola Y.C.Ma. (CD) has been used for "reinforcing kidney yang" for thousand years. Although CD has been extensively studied for OP management, active components and mechanism of CD on OPOA treatment remain elusive.

Aim of the study: This study aims to investigate the impact of osteoporosis (OP) conditions on OPOA progression and elucidate the active components and mechanisms underlying the therapeutic effects of CD in OPOA.

Materials and methods: OP rat model was established by ovariectomy (OVX) and OPOA rat model was established by combining the established OP model with destabilization of the medial meniscus surgery. The bone-protective effects of CD on OP and OPOA rats were evaluated by assessing serum estrogen levels, bone metabolism markers, inflammatory cytokines, micro-CT scanning, and cartilage histology. UPLC-Q-TOF/MS was employed to analyze constituents of CD present in the bloodstream of OPOA rats. Network pharmacology, molecular docking, qRT-PCR, cellular thermal shift assay (CETSA), molecular dynamics simulations were used to screen and verify interaction between the active compound secologanic acid (SA) and key pathway genes. Finally, the expression of the phosphatidylinositol 3-kinase/serine-threonine protein kinase B/hypoxia-inducible factor 1 alpha (PI3K/Akt/HIF-1α) pathway proteins and extracellular matrix (ECM)-related proteins was detected both in vivo and in vitro using Western blotting and immunohistochemistry.

Results: CD significantly ameliorated estrogen levels, serum bone turnover markers, and inflammatory cytokine levels in OP rats. Additionally, CD substantially alleviated pain behaviors, reversed bone microstructure deterioration, and inhibited cartilage degradation in OPOA rats. Fourteen prototype components were detected in the systemic circulation of OPOA rats after CD intervention, among which SA was identified as the key active constituent. Molecular docking, qRT-PCR, CETASA and molecular dynamics simulations revealed Akt1 emerged as a key potential target of SA. OPOA was ameliorated by CD and SA both in vivo and in vitro through suppression of the PI3K/Akt/HIF-1α pathway and restoration of cartilage ECM homeostasis.

Conclusions: This study reveals that OP represents a potential driver for OPOA progression. CD ameliorated the progression of both OP and OPOA by alleviating bone metabolic imbalance and restoring ECM homeostasis. Mechanistically, CD could inhibit PI3K/Akt/HIF-1α signaling pathway, thereby restoring bone metabolic equilibrium and cartilage ECM homeostasis. This study provides modern pharmacological substantiation for CD's traditional kidney-tonifying and bone-strengthening effects in OPOA treatment.

Cistanche deserticola Y.C.Ma.; Network pharmacology; OPOA; PI3K/AKT/HIF-1α; Serum medicinal chemistry.