Ozone induces autophagy by activating PPARγ/mTOR in rat chondrocytes treated with IL-1ß.

BACKGROUND: Osteoarthritis (OA) is the main cause of older pain and disability. Intra-articular injections of ozone (O3) commonly have been found to have antioxidative and anti-inflammatory effects to reduce pain and improve function in knee osteoarthritis. It has been reported that reduced autophagy in chondrocytes plays an important role in the development of OA. This study aimed to probe the role of O3 on the autophagy in chondrocytes treated with IL-1ß. METHODS: Primary chondrocytes were isolated from Wistar rats cartilage within 3 days. The OA chondrocytes model was induced via treatment with IL-1ß for 24 h. Then the cells were treated with O3 and GW9662, the inhibitor of PPARγ. Cell viability was assessed by CCK-8. Further, the cells subjected to Western blot analysis, qRT-PCR and immunofluorescence assay. The numbers of autophagosomes were observed via transmission electron microscopy. RESULTS: 30 µg/ml O3 improved the viability of chondrocytes treated with IL-1ß. The decreased level of autophagy proteins and the numbers of autophagosomes improved in IL-1ß-treated chondrocytes with O3 via activating PPARγ/mTOR. In addition, the qRT-PCR results showed that O3 decreased the levels of IL-6, TNF-α and MMP-3, MMP-13 in chondrocytes treated with IL-1ß. CONCLUSIONS: 30 µg/ml O3 improved autophagy via activating PPARγ/mTOR signaling and suppressing inflammation in chondrocytes treated with IL-1ß.

METTL3 suppresses neuropathic pain via modulating N6-methyladenosine-dependent primary miR-150 processing.

Methyltransferase-like 3 (METTL3)-modulated N6-methyladenosine (m6A) was recently identified as an important epigenetic regulation type during RNA processing and contributes to multiple pathological processes. Neuropathic pain (NP) is induced by a lesion of the somatosensory nervous system, and the detailed pathways by which METTL3/m6A regulated to modulate gene dysregulation and enable NP have remained unclear. Therefore, this study investigated the function of METTL3-mediated m6A methylation on miRNA maturation, and investigated how this regulation contributes to NP progression. A rat model characterized with typical NP was established by a spared nerve-injury (SNI) method. By analyzing the expression levels of METTL3 and m6A methylation, we found that METTL3, along with m6A methylation, was dramatically downregulated in NP rats in contrast to the sham ones. Functionally, enhanced METTL3 promoted the m6A methylation in total RNAs and inhibited NP progression, whereas silencing METTL3 suppressed m6A methylation and increased NP severity. Mechanistically, METTL3 accelerated miR-150 maturation via mediating m6A methylation of primiR-150 at locus 498, cooperating with the "m6A reader" YTHDF2. Meanwhile, miR-150 could directly target brain-derived neurotrophic factor (BDNF) mRNA, and the METTL3/miR-150/BDNF regulatory pathway was finally established. Clinically, we proved that serum METTL3 mRNA was also downregulated in Shingles patients with NP, suggesting its diagnostic potential. In conclusion, we demonstrated an essential function of METTL3-regulated N6-methyladenosine during NP progression via modulating primiR-150 maturation. Serum METTL3 could effectively differentiate NP patients from healthy people, and is useful for dynamic monitoring of diseases after treatment. Therefore, the METTL3/miR-150/BDNF pathway may be a promising therapeutic target for NP patients.

Dysfunction of inflammation-resolving pathways is associated with postoperative cognitive decline in elderly mice.

BACKGROUND: Postoperative cognitive dysfunction (POCD) refers to a reversible, perioperative mental disorder. POCD increases the likelihood of postoperative complications and the risk for postoperative mortality, typically among elderly patients (age 65 or older). The importance of the cholinergic anti-inflammatory pathway (CAP) in resolving neuro-inflammatory and cognitive decline caused by sterile trauma has been recognized. We speculate that the POCD in elderly mice is associated with dysfunction of CAP. METHODS: Mice were assigned to several groups (n = 5 in each group): AM (adult mice) Sham, AM (adult mice) Surgery, EM (elderly mice) Sham, EM (elderly mice) Surgery, and EMP (elderly mice with PNU) Surgery. At 24 h after surgery, assessed the cognitive levels. Pro-inflammatory cytokines in peripheral blood and splenic monocytes (TNF-α, IL-6 and IL-10) were assessed by ELISA and qPCR. Levels of M2 macrophages in hippocampus were visualized by immunofluorescence. Detecting CD11b/c+α7 nAChR+ cells in the spleens with flow cytometry. RESULTS: At postoperative 24 h, elderly mice exhibited significantly increased POCD compared with adult mice. The proinflammatory factor TNF-α and IL-6 were higher among elderly surgery mice (EM) compared with adult surgery (AM) and elderly-P surgery mice (EM-P); the anti-inflammatory factor IL-10 and M2 macrophages were lower among EM surgery mice compared with AM surgery and EM-P surgery mice. The CD11b/c+α7 nAChR+ population of splenocytes was reduced in the EM surgery mice. CONCLUSIONS: The exaggerated and persistent cognitive decline and inflammatory response among elderly mice were associated with dysfunction of CAP, and these phenomena were reversed by α7nAch receptor agonists.