Carpaine alleviates tendinopathy in mice by promoting the ubiquitin-proteasomal degradation of p65 via targeting the E3 ubiquitin ligase LRSAM1.

BACKGROUND: Currently, there are no specific drugs or targets available for the treatment of tendinopathy. However, inflammation has recently been found to play a pivotal role in tendinopathy progression, thereby identifying it as a potential therapeutic target. Carpaine (CA) exhibits potential anti-inflammatory pharmacological properties and may offer a therapeutic option for tendinopathy. PURPOSE: This study aimed to investigate the effectiveness of CA in addressing tendinopathy and uncovering its underlying mechanisms. METHODS: Herein, the efficacy of CA by local administration in vivo in comparison to the first-line drug indomethacin was evaluated in a mouse collagenase-induced tendinopathy (CIT) model. Furthermore, IL-1ß induced a simulated pathological inflammatory microenvironment in tenocytes to investigate its underlying mechanisms in vitro. Further confirmation experiments were performed by overexpressing or knocking down the selective targets of CA in vivo. RESULTS: The findings demonstrated that CA was dose-dependent in treating tendinopathy and that the high-dose group outperformed the first-line drug indomethacin. Mechanistically, CA selectively bound to and enhanced the activity of the E3 ubiquitin ligase LRSAM1 in tendinopathy. This effect mediated the ubiquitination of p65 at lysine 93, subsequently promoting its proteasomal degradation. As a result, the NF-κB pathway was inactivated, leading to a reduction in inflammation of tendinopathy. Consequently, CA effectively mitigated the progression of tendinopathy. Moreover, the LRSAM1 overexpression demonstrated effectiveness in mitigating the tendinopathy progression and its knockdown abolished the therapeutic effects of CA. CONCLUSION: CA attenuates the progression of tendinopathy by promoting the ubiquitin-proteasomal degradation of p65 via increasing the enzyme activity of LRSAM1. The exploration of LRSAM1 has also unveiled a new potential target for treating tendinopathy based on the ubiquitin-proteasomal pathway.

Electroacupuncture Attenuates Cancer-Induced Bone Pain via NF-κB/CXCL12 Signaling in Midbrain Periaqueductal Gray.

Electroacupuncture (EA) is effective in various chronic pains. NF-κB and CXCL12 modulate the formation of chronic pain. Herein, we hypothesized that EA alleviates cancer-induced bone pain (CIBP) through NF-κB/CXCL12 axis in midbrain periaqueductal gray (PAG), which participates in "top-down" pain modulatory circuits. In order to filter the optimum EA frequency for CIBP treatment, 2, 100, or 2/100 Hz EA was set up. In addition, ipsilateral, contralateral, and bilateral EA groups were established to affirm the optimal EA scheme. Bilateral 2/100 Hz EA was considered as the optimal therapeutic scheme and was applied in a subsequent experiment. Western blotting along with immunofluorescence illustrated that CIBP induces a rapid and substantial increase in CXCL12 protein level and NF-κB phosphorylation in vlPAG from day 6 to day 12. Anti-CXCL12 neutralizing antibody and pAAV-U6-shRNA(CXCL12)-CMV-EGFP-WPRE in vlPAG remarkably improved the mechanical pain threshold of the hind paw in CIBP model relative to the control. EA inhibited the upregulation of pNF-κB and CXCL12 in vlPAG of CIBP. The recombinant CXCL12 and pAAV-CMV-CXCL12-EF1a-EGFP-3Xflag-WPRE reversed the abirritation of EA in the CIBP rat model. NF-κB phosphorylation mediated-CXCL12 expression contributed to CIBP allodynia, whereas EA suppressed NF-κB phosphorylation in CIBP. According to the above evidence, we conclude that bilateral 2/100 Hz EA is an optimal therapeutic scheme for CIBP. The abirritation mechanism of EA might reduce the expression of CXCL12 by inhibiting the activation of NF-κB, which might lead to the restraint of descending facilitation of CIBP.