RESUMO
Objectives: The aim of this study was to investigate the effects of low-intensity pulsed ultrasound (LIPUS) in a post-traumatic osteoarthritis (OA) rat model and in vitro. Methods: Thirty-eight male, four-month-old Sprague Dawley rats were randomly assigned to Sham, Sham â+ âUS, OA, and OA â+ âUS. Sham surgery was performed to serve as a negative control, and anterior cruciate ligament transection was used to induce OA. Three days after the surgical procedures, Sham â+ âUS and OA â+ âUS animals received daily LIPUS treatment, while the rest of the groups received sham ultrasound (US) signals. Behavioral pain tests were performed at baseline and every week thereafter. After 31 days, the tissues were collected, and histological analyses were performed on knees and innervated dorsal root ganglia (DRG) neurons traced by retrograde labeling. Furthermore, to assess the activation of osteoclasts by LIPUS treatment, RAW264.7 âcells were differentiated into osteoclasts and treated with LIPUS. Results: Joint degradation in cartilage and bone microarchitecture were mitigated in OA â+ âUS compared to OA. OA â+ âUS showed improvements in behavioral pain tests. A significant increase of large soma-sized DRG neurons was located in OA compared to Sham. In addition, a greater percentage of large soma-sized innervated neurons were calcitonin gene-related peptide-positive. Daily LIPUS treatment suppressed osteoclastogenesis in vitro, which was confirmed via histological analyses and mRNA expression. Finally, lower expression of netrin-1, a sensory innervation-related protein, was found in the LIPUS treated cells. Conclusion: Our findings demonstrate that early intervention using LIPUS treatment has protective effects from the progression of knee OA, including reduced tissue degradation, mitigated pain characteristics, improved subchondral bone microarchitecture, and less sensory innervation. Furthermore, daily LIPUS treatment has a suppressive effect on osteoclastogenesis, which may be linked to the suppression of sensory innervation in OA. The translational potential of this article: This study presents a new potential for early intervention in treating OA symptoms through the use of LIPUS, which involves the suppression of osteoclastogenesis and the alteration of DRG profiles. This intervention aims to delay joint degradation and reduce pain.
RESUMO
Cadmium (Cd) is one of the common heavy metal pollutants in soil, which can induce various diseases and pose a serious threat to human health. Metallothioneins (MTs) are well-known for their excellent metal binding ability due to a high content of cysteine, which has great potential for heavy metal chelation. In this study, we used the Escherichia coli (E. coli) surface display system LPP-OmpA to construct a recombinant plasmid pBSD-LCF encoding LPP-OmpA-CUP1-Flag fusion protein. Then we displayed the metallothionein CUP1 from Saccharomyces cerevisiae on E. coli DH5α surface for Cd removing. The feasibility of surface display of metallothionein CUP1 in recombinant E. coli DH5α (pBSD-LCF) by Lpp-OmpA system was proved by flow cytometry and western blot analysis, and the specificity of the fusion protein in the recombinant strain was also verified. The results showed that the Cd2+ resistance capacity of DH5α (pBSD-LCF) was highly enhanced by about 200%. Fourier-transform infrared spectroscopy showed that sulfhydryl and sulfonyl groups were involved in Cd2+ binding to cell surface of DH5α (pBSD-LCF). Meanwhile, Cd removal rate by DH5α (pBSD-LCF) was promoted to 95.2%. Thus, the recombinant strain E. coli DH5α (pBSD-LCF) can effectively chelate environmental metals, and the cell surface expression of metallothionein on E. coli can provide new ideas and directions for heavy metals remediation.