SQSTM1-dependent autophagic degradation of PKM2 inhibits the production of mature IL1B/IL-1β and contributes to LIPUS-mediated anti-inflammatory effect

Extracellular vesicles derived from human umbilical cord mesenchymal stem cells alleviate osteoarthritis of the knee in mice model by interacting with METTL3 to reduce m6A of NLRP3 in macrophage

BACKGROUND

Osteoarthritis (OA) is a prevalent degenerative joint disease that not only significantly impairs the quality of life of middle-aged and elderly individuals but also imposes a significant financial burden on patients and society. Due to their significant biological properties, extracellular vesicles (EVs) have steadily received great attention in OA treatment. This study aimed to investigate the influence of EVs on chondrocyte proliferation, migration, and apoptosis and their protective efficacy against OA in mice.

METHODS

The protective impact of EVs derived from human umbilical cord mesenchymal stem cells (hucMSCs-EVs) on OA in mice was investigated by establishing a mouse OA model by surgically destabilizing the medial meniscus (DMM). Human chondrocytes were isolated from the cartilage of patients undergoing total knee arthroplasty (TKA) and cultured with THP-1 cells to mimic the in vivo inflammatory environment. Levels of inflammatory factors were then determined in different groups, and the impacts of EVs on chondrocyte proliferation, migration, apoptosis, and cartilage extracellular matrix (ECM) metabolism were explored. N6-methyladenosine (m6A) level of mRNA and methyltransferase-like 3 (METTL3) protein expression in the cells was also measured in addition to microRNA analysis to elucidate the molecular mechanism of exosomal therapy.

RESULTS

The results indicated that hucMSCs-EVs slowed OA progression, decreased osteophyte production, increased COL2A1 and Aggrecan expression, and inhibited ADAMTS5 and MMP13 overexpression in the knee joint of mice via decreasing pro-inflammatory factor secretion. The in vitro cell line analysis revealed that EVs enhanced chondrocyte proliferation and migration while inhibiting apoptosis. METTL3 is responsible for these protective effects. Further investigations revealed that EVs decreased the m6A level of NLRP3 mRNA following miR-1208 targeted binding to METTL3, resulting in decreased inflammatory factor release and preventing OA progression.

CONCLUSION

This study concluded that hucMSCs-EVs inhibited the secretion of pro-inflammatory factors and the degradation of cartilage ECM after lowering the m6A level of NLRP3 mRNA with miR-1208 targeting combined with METTL3, thereby alleviating OA progression in mice and providing a novel therapy for clinical OA treatment.

Capsaicin ameliorates inflammation in a TRPV1-independent mechanism by inhibiting PKM2-LDHA-mediated Warburg effect in sepsis

Sepsis is a systemic inflammatory response syndrome with high mortality and morbidity worldwide. In this study, we demonstrate that capsaicin not only suppresses inflammation in lipopolysaccharide (LPS)-induced macrophages, but also effectively inhibits endotoxemia or sepsis-related inflammation in vivo. We have designed and synthesized a series of capsaicin-based probes, which permit the profiling of the target proteins of capsaicin using activity-based protein profiling (ABPP). Among the identified protein targets, we discover that capsaicin directly binds to and inhibits PKM2 and LDHA, and further suppresses the Warburg effect in inflammatory macrophages. Moreover, capsaicin targets COX-2 and downregulates its expression in vivo and in vitro. Taken together, the present findings indicate that capsaicin alleviates the inflammation response and the Warburg effect in a TRPV1-independent manner by targeting PKM2-LDHA and COX-2 in sepsis. Thus, capsaicin may function as a novel agent for sepsis and inflammation treatment.

Single-Cell Profiles of Age-Related Osteoarthritis Uncover Underlying Heterogeneity Associated With Disease Progression

Objective: Osteoarthritis (OA) is the most common chronic degenerative joint disease, which represents the leading cause of age-related disability. Here, this study aimed to depict the intercellular heterogeneity of OA synovial tissues.

Methods: Single-cell RNA sequencing (scRNA-seq) data were preprocessed and quality controlled by the Seurat package. Cell cluster was presented and cell types were annotated based on the mRNA expression of corresponding marker genes by the SingleR package. Cell-cell communication was assessed among different cell types. After integrating the GSE55235 and GSE55457 datasets, differentially expressed genes were identified between OA and normal synovial tissues. Then, differentially expressed marker genes were overlapped and their biological functions were analyzed.

Results: Totally, five immune cell subpopulations were annotated in OA synovial tissues including macrophages, dendritic cells, T cells, monocytes and B cells. Pseudo-time analysis revealed the underlying evolution process in the inflammatory microenvironment of OA synovial tissue. There was close crosstalk between five cell types according to the ligand-receptor network. The genetic heterogeneity was investigated between OA and normal synovial tissues. Furthermore, functional annotation analysis showed the intercellular heterogeneity across immune cells in OA synovial tissues.

Conclusion: This study offered insights into the heterogeneity of OA, which provided in-depth understanding of the transcriptomic diversities within synovial tissue. This transcriptional heterogeneity may improve our understanding on OA pathogenesis and provide potential molecular therapeutic targets for OA.

Low-intensity pulsed ultrasound therapy suppresses coronary adventitial inflammatory changes and hyperconstricting responses after coronary stent implantation in pigs in vivo

Backgrounds

We demonstrated that coronary adventitial inflammation plays important roles in the pathogenesis of drug-eluting stent (DES)-induced coronary hyperconstricting responses in pigs in vivo. However, no therapy is yet available to treat coronary adventitial inflammation. We thus developed the low-intensity pulsed ultrasound (LIPUS) therapy that ameliorates myocardial ischemia by enhancing angiogenesis.

Aims

We aimed to examine whether our LIPUS therapy suppresses DES-induced coronary hyperconstricting responses in pigs in vivo, and if so, what mechanisms are involved.

Methods

Sixteen normal male pigs were randomly assigned to the LIPUS or the sham therapy groups after DES implantation into the left anterior descending (LAD) coronary artery. In the LIPUS group, LIPUS (32 cycles, 193 mW/cm²) was applied to the heart at 3 different levels (segments proximal and distal to the stent edges and middle of the stent) for 20 min at each level for every other day for 2 weeks. The sham therapy group was treated in the same manner but without LIPUS. At 4 weeks after stent implantation, we performed coronary angiography, followed by immunohistological analysis.

Results

Coronary vasoconstricting responses to serotonin in LAD at DES edges were significantly suppressed in the LIPUS group compared with the sham group. Furthermore, lymph transport speed in vivo was significantly faster in the LIPUS group than in the sham group. Histological analysis at DES edges showed that inflammatory changes and Rho-kinase activity were significantly suppressed in the LIPUS group, associated with eNOS up-regulation and enhanced lymph-angiogenesis.

Conclusions

These results suggest that our non-invasive LIPUS therapy is useful to treat coronary functional abnormalities caused by coronary adventitial inflammation, indicating its potential for the novel and safe therapeutic approach of coronary artery disease.

Low-intensity pulsed ultrasound inhibits fibroblast-like synoviocyte proliferation and reduces synovial fibrosis by regulating Wnt/β-catenin signaling

OBJECTIVE

Synovial fibrosis is a characteristic symptom of osteoarthritis (OA), which is closely associated with joint pain and stiffness. Previous studies have reported that low-intensity pulsed ultrasound (LIPUS) can alleviate cartilage degradation in OA. However, the functions and mechanisms of LIPUS in OA synovial fibrosis are still unknown.

METHODS

The destabilization of the medial meniscus (DMM) mouse model of OA was established in C57 male mice and fibroblast-like synoviocytes (FLS) were isolated from synovial tissue of OA patients. The knee joint diameter, Masson's trichrome (MT) and Hematoxylin-eosin (HE) staining were used to evaluate synovial fibrosis and hyperplasia. The Immunohistochemistry (IHC) staining was performed to detected the expression of synovial fibrosis makers and the activation of Wnt/β-catenin signaling in vivo. FLS were treated with TGF-β1 to serve as an in vitro model of synovial fibrosis, Wnt3a was used to activate the Wnt/β-catenin signaling in cells. Cell proliferation was detected by using EdU assay, cell viability was performed by CCK8 assay. The protein levels of α-SMA, CTGF, Col Ⅰ, β-catenin, active β-catenin, c-Myc and cyclin D1 were examined by western blot and immunofluorescence staining.

RESULTS

Two weeks after the LIPUS treatment, the synovial fibrosis, synovial hyperplasia and synoviocyte proliferation in the DMM model were significantly decreased. In vitro, LIPUS directly inhibited the TGF-β1-induced fibrotic response and proliferation of FLS. Meanwhile, LIPUS suppressed Wnt/β-catenin signaling in the synovium of DMM mice and cultured FLS. More importantly, we found that the synovial fibrosis makers, Wnt/β-catenin pathway downstream proteins and FLS proliferation were significantly decreased in Wnt3a-stimulated FLS following LIPUS treatment.

CONCLUSIONS

Our results present a novel role of LIPUS in OA-related synovial fibrosis, which is associated with its ability to repress Wnt/β-catenin signaling in FLS.

THE TRANSLATIONAL POTENTIAL OF THIS ARTICLE

This study provides new insight into the clinical application of LIPUS as a therapeutic option to manage synovial fibrosis in OA.

Glycitin Suppresses Cartilage Destruction of Osteoarthritis in Mice

Osteoarthritis (OA), a chronic joint disease, is characterized by cartilage surface erosion, subchondral bone rebuilding, and formation of osteophytes. To date, the nosogenesis and underlying mechanisms of OA have not yet been elucidated. However, it is widely accepted that TNF-α is a crucial cytokine in the development of OA. Glycitin, a natural isoflavone extracted from legumes, affects physiological reactions and pathological responses. Recently, the anti-inflammatory effect of glycitin has been reported. However, the function of glycitin in cartilage degeneration in OA remains to be investigated. In the current study, primary murine chondrocytes were isolated and stimulated by TNF-α to evaluate the anti-inflammatory effects and protective function of glycitin in chondrocytes. In vivo, the ACLT mouse model, a frequently-used OA model, was used to further examine the therapeutic role of glycitin in cartilage degeneration and inflammation in OA. Consequently, glycitin functions were examined both in vivo and in vitro. Moreover, the underlying mechanism of action of glycitin was investigated and was found to involve the NF-κB signaling pathway. Collectively, this study suggests that glycitin can be potentially used for the treatment of joint degenerative diseases, including OA.

Pyruvate Kinase M2 Contributes to TLR-Mediated Inflammation and Autoimmunity by Promoting Pyk2 Activation

Toll-like receptors (TLRs) play critical roles in regulating the abnormal activation of the immune cells resulting in the pathogenesis of inflammation and autoimmune diseases. Pyruvate kinase M2 (PKM2), which governs the last step of glycolysis, is involved in multiple cellular processes and pathological conditions. However, little is known about the involvement of PKM2 in regulating TLR-mediated inflammation and autoimmunity. Herein, we investigated the role of PKM2 in the activation of the TLR pathways and the pathogenesis of inflammation and autoimmune diseases. The activation of TLR4, TLR7 and TLR9 pathways was found to induce the up-regulation of PKM2 expression in macrophages, dendritic cells (DCs) and B cells. The over-expression of PKM2 promotes the activation of TLR4, TLR7 and TLR9 pathways while interference with the PKM2 expression or the addition of the PKM2 inhibitor (PKM-IN) markedly inhibited the activation of TLR4, TLR7 and TLR9 pathways. Mechanistically, PKM2 augmented the activation of TLR4, TLR7 and TLR9 pathways by promoting the activation of the proline-rich tyrosine kinase 2 (Pyk2). Intriguingly, the PKM2 inhibitor PKM2-IN significantly protected the mice from the endotoxic shock mediated by the TLR4-agonist LPS. Additionally, it alleviated the progression in the TLR7-agonist imiquimod-mediated lupus mice and spontaneous lupus MRL/lpr mice. Moreover, PKM2 expression was highly elevated in the monocytes, DCs and B cells from systemic lupus erythematous (SLE) patients compared with those from the healthy donors. Besides, the PKM2 expression level was positively correlated with the degree of activation of these immune cells. In summary, PKM2 contributed to TLR-mediated inflammation and autoimmunity and can be a valuable target to control inflammation and autoimmunity.

An update on the regulatory mechanisms of NLRP3 inflammasome activation

The NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome is a multiprotein complex involved in the release of mature interleukin-1β and triggering of pyroptosis, which is of paramount importance in a variety of physiological and pathological conditions. Over the past decade, considerable advances have been made in elucidating the molecular mechanisms underlying the priming/licensing (Signal 1) and assembly (Signal 2) involved in NLRP3 inflammasome activation. Recently, a number of studies have indicated that the priming/licensing step is regulated by complicated mechanisms at both the transcriptional and posttranslational levels. In this review, we discuss the current understanding of the mechanistic details of NLRP3 inflammasome activation with a particular emphasis on protein-protein interactions, posttranslational modifications, and spatiotemporal regulation of the NLRP3 inflammasome machinery. We also present a detailed summary of multiple positive and/or negative regulatory pathways providing upstream signals that culminate in NLRP3 inflammasome complex assembly. A better understanding of the molecular mechanisms underlying NLRP3 inflammasome activation will provide opportunities for the development of methods for the prevention and treatment of NLRP3 inflammasome-related diseases.

Low-intensity pulsed ultrasound inhibits IL-6 in subchondral bone of temporomandibular joint osteoarthritis by suppressing the TGF-β1/Smad3 pathway

OBJECTIVE

This study aimed to provide further information on the exact mechanisms involved in the anti-inflammatory effect of low-intensity pulsed ultrasound (LIPUS) on rabbit temporomandibular joint osteoarthritis (TMJOA) on interleukin-6 (IL-6) production in subchondral bone, IL-6 production in IL-1β stimulated via inhibition of the TGF-β1/Smad3 pathway in mouse embryo osteoblast precursor (MC3T3-E1) cells.

DESIGN

Bilateral joints were injected with type II collagenase to establish TMJOA models in two male and four female rabbits. The left joint was continuously stimulated by LIPUS, while the right joint was treated with the power off in this model. One male and two female rabbits were used as normal healthy controls without treatment. The histological features of subchondral bone were examined by Safranin-O/Fast staining. Immunohistochemistry was conducted to evaluate IL-6 expression. Then, cells were stimulated by LIPUS with IL-1β. IL-6 expression and activity of the TGF-β1/Smad3 pathway were evaluated by Enzyme-linked immunosorbent assay (ELISA), Immunofluorescence and Western blotting, respectively. Specific inhibition of the TGF-β1/Smad3 pathway was conducted by transfecting with small interfering RNA (siRNA) of type II receptor (siTβRII).

RESULTS

LIPUS significantly ameliorated the production of IL-6 in vitro and in vivo. Its inhibitory effect on the production of IL-6 induced by IL-1β in MC3T3-E1 cells was partly reversed by siTβRII knockdown.

CONCLUSIONS

LIPUS inhibited IL-6 production by suppressing the TGF-β1/Smad3 pathway of subchondral bone in TMJOA. These data revealed the part of the pathways involved in the anti-inflammatory effect of LIPUS and provided a possible treatment strategy for TMJOA patients and other inflammatory diseases.

Review on experimental study and clinical application of low-intensity pulsed ultrasound in inflammation

Low-intensity pulsed ultrasound (LIPUS), as physical therapy, is widely used in both research and clinical settings. It induces multiple bioeffects, such as alleviating pain, promoting tissue repair, and shortening disease duration. LIPUS can also mediate inflammation. This paper reviews the application of LIPUS in inflammation and discusses the underlying mechanism. In basic experiments, LIPUS can regulate inflammatory responses at the cellular level by affecting some signaling pathways. In a clinical trial, LIPUS has been shown to alleviate inflammatory responses efficiently. As a cheap, safe, and convenient physical method, LIPUS is promising as anti-inflammatory therapy.

Rapamycin-Induced Autophagy Promotes the Chondrogenic Differentiation of Synovium-Derived Mesenchymal Stem Cells in the Temporomandibular Joint in Response to IL-1β

Cartilage defects in temporomandibular disorders (TMD) lead to chronic pain and seldom heal. Synovium-derived mesenchymal stem cells (SMSCs) exhibit superior chondrogenesis and have become promising seed cells for cartilage tissue engineering. However, local inflammatory conditions that affect the repair of articular cartilage by SMSCs present a challenge, and the specific mechanism through which the function remains unclear. Thus, it is important to explore the chondrogenesis of SMSCs under inflammatory conditions of TMD such that they can be used more effectively in clinical treatment. In this study, we obtained SMSCs from TMD patients with severe cartilage injuries. In response to stimulation with IL-1β, which is well known as one of the most prevalent cytokines in TMD, MMP13 expression increased, while that of SOX9, aggrecan, and collagen II decreased during chondrogenic differentiation. At the same time, IL-1β upregulated the expression of mTOR and decreased the ratio of LC3-II/LC3-I and the formation of autophagosomes. Further study revealed that rapamycin pretreatment promoted the migration of SMSCs and the expression of chondrogenesis-related markers in the presence of IL-1β by inducing autophagy. 3-Benzyl-5-((2-nitrophenoxy)methyl)-dihydrofuran-2(3H)-one (3BDO), a new activator of mTOR, inhibited autophagy and increased the expression of p-GSK3βser9 and β-catenin, simulating the effect of IL-1β stimulation. Furthermore, rapamycin reduced the expression of mTOR, whereas the promotion of LC3-II/LC3-I was blocked by the GSK3β inhibitor TWS119. Taken together, these results indicate that rapamycin enhances the chondrogenesis of SMSCs by inducing autophagy, and GSK3β may be an important regulator in the process of rapamycin-induced autophagy. Thus, inducing autophagy may be a useful approach in the chondrogenic differentiation of SMSCs in the inflammatory microenvironment and may represent a novel TMD treatment.

Ultrasound Therapy: Experiences and Perspectives for Regenerative Medicine

Ultrasound has emerged as a novel tool for clinical applications, particularly in the context of regenerative medicine. Due to its unique physico-mechanical properties, low-intensity ultrasound (LIUS) has been approved for accelerated fracture healing and for the treatment of established non-union, but its utility has extended beyond tissue engineering to other fields, including cell regeneration. Cells and tissues respond to acoustic ultrasound by switching on genetic repair circuits, triggering a cascade of molecular signals that promote cell proliferation, adhesion, migration, differentiation, and extracellular matrix production. LIUS also induces angiogenesis and tissue regeneration and has anti-inflammatory and anti-degenerative effects. Accordingly, the potential application of ultrasound for tissue repair/regeneration has been tested in several studies as a stand-alone treatment and, more recently, as an adjunct to cell-based therapies. For example, ultrasound has been proposed to improve stem cell homing to target tissues due to its ability to create a transitional and local gradient of cytokines and chemokines. In this review, we provide an overview of the many applications of ultrasound in clinical medicine, with a focus on its value as an adjunct to cell-based interventions. Finally, we discuss the various preclinical and clinical studies that have investigated the potential of ultrasound for regenerative medicine.

The Optimal Regimen for the Treatment of Temporomandibular Joint Injury Using Low-Intensity Pulsed Ultrasound in Rats with Chronic Sleep Deprivation

Low-intensity pulsed ultrasound (LIPUS) is an emerging physical therapy for the treatment of early temporomandibular joint injury and has a good effect on promoting cartilage and subchondral bone tissue repair. However, the best LIPUS intensity and treatment duration remain unclear. This study is aimed at observing the preventive and therapeutic effects of different modes of LIPUS and at identifying the optimal LIPUS treatment regimen for temporomandibular joint injury. In the present study, rat models of temporomandibular joint injury were established using a chronic sleep deprivation (CSD) method, and the effect of LIPUS as intensities of 30, 45, and 60 mW/cm² was observed at 7, 14, and 21 days. After CSD, the condylar cartilage of the rats demonstrated variable degrees of surface roughening, collagen fiber disarrangement or even partial exfoliation, decreased proteoglycan synthesis and cartilage thickness, decreased chondrocyte proliferation, decreased type 2 collagen (COL-2) expression, and increased matrix metalloproteinase- (MMP-) 3 expression at all three time points. When the rats with CSD received different intensities of LIPUS treatment, the pathological changes were alleviated to various extents. The groups receiving 45 mW/cm² LIPUS showed the most significant relief of cartilage damage, and this significant effect was observed on days 14 and 21. These results demonstrated that LIPUS can effectively inhibit CSD-induced condylar cartilage damage in rats, and LIPUS treatment at an intensity of 45 mW/cm² for at least 2 weeks is the optimal regimen for temporomandibular joint injury.

Low-intensity pulsed ultrasound inhibits VEGFA expression in chondrocytes and protects against cartilage degeneration in experimental osteoarthritis

Low-intensity pulsed ultrasound (LIPUS), a noninvasive physical therapy, was recently demonstrated to be an effective treatment for osteoarthritis (OA). Vascular endothelium growth factor A (VEGFA) has been found to be upregulated in the articular cartilage, synovium and subchondral bone of OA patients, leading to cartilage degeneration, synovitis and osteophyte formation. However, the functions and mechanisms of LIPUS in regulating chondrocyte-derived VEGFA expression are still unclear. In this study, we investigated whether LIPUS attenuated OA progression by (a) decreasing the percentage of VEGFA-positive cells in mouse articular cartilage destabilised through medial meniscus surgery and (b) relieving interleukin-1β-induced VEGFA expression in mouse primary chondrocytes. However, this function was negated by a p38 mitogen-activated protein kinase (p38 MAPK) inhibitor. In addition, we found that LIPUS ameliorated VEGFA-mediated disorders in cartilage extracellular matrix metabolism and chondrocyte hypertrophy during OA development. In conclusion, our data indicate a novel effect of LIPUS in regulating the expression of osteoarthritic chondrocyte-derived VEGFA through the suppression of p38 MAPK activity.