LIPUS suppressed LPS-induced IL-1α through the inhibition of NF-κB nuclear translocation via AT1-PLCβ pathway in MC3T3-E1 cells

Low-Intensity Pulsed Ultrasound: A Physical Stimulus with Immunomodulatory and Anti-inflammatory Potential

Ultrasound has expanded into the therapeutic field as a medical imaging and diagnostic technique. Low-intensity pulsed ultrasound (LIPUS) is a kind of therapeutic ultrasound that plays a vital role in promoting fracture healing, wound repair, immunomodulation, and reducing inflammation. Its anti-inflammatory effects are manifested by decreased pro-inflammatory cytokines and chemokines, accelerated regression of immune cell invasion, and accelerated damage repair. Although the anti-inflammatory mechanism of LIPUS is not very clear, many in vitro and in vivo studies have shown that LIPUS may play its anti-inflammatory role by activating signaling pathways such as integrin/Focal adhesion kinase (FAK)/Phosphatidylinositol 3-kinase (PI3K)/Serine threonine kinase (Akt), Vascular endothelial growth factor (VEGF)/endothelial nitric oxide synthase (eNOS), or inhibiting signaling pathways such as Toll-like receptors (TLRs)/Nuclear factor kappa-B (NF-κB) and p38-Mitogen-activated protein kinase (MAPK). As a non-invasive physical therapy, the anti-inflammatory and immunomodulatory effects of LIPUS deserve further exploration.

Epimedium-Curculigo herb pair enhances bone repair with infected bone defects and regulates osteoblasts through LncRNA MALAT1/miR-34a-5p/SMAD2 axis

Infected bone defects (IBDs) are the common condition in the clinical practice of orthopaedics. Although surgery and anti-infective medicine are the firstly chosen treatments, in many cases, patients experience a prolonged bone union process after anti-infective treatment. Epimedium-Curculigo herb pair (ECP) has been proved to be effective for bone repair. However, the mechanisms of ECP in IBDs are insufficiency. In this study, Effect of ECP in IBDs was verified by micro-CT and histological examination. Qualitative and quantitative analysis of the main components in ECP containing medicated serum (ECP-CS) were performed. The network pharmacological approaches were then applied to predict potential pathways for ECP associated with bone repair. In addition, the mechanism of ECP regulating LncRNA MALAT1/miRNA-34a-5p/SMAD2 signalling axis was evaluated by molecular biology experiments. In vivo experiments indicated that ECP could significantly promote bone repair. The results of the chemical components analysis and the pathway identification revealed that TGF-β signalling pathway was related to ECP. The results of in vitro experiments indicated that ECP-CS could reverse the damage caused by LPS through inhibiting the expressions of LncRNA MALAT1 and SMAD2, and improving the expressions of miR-34a-5p, ALP, RUNX2 and Collagen type І in osteoblasts significantly. This research showed that ECP could regulate the TGF-β/SMADs signalling pathway to promote bone repair. Meanwhile, ECP could alleviate LPS-induced bone loss by modulating the signalling axis of LncRNA MALAT1/miRNA-34a-5p/ SMAD2 in IBDs.

Co-Stimulation of AGEs and LPS Induces Inflammatory Mediators through PLCγ1/JNK/NF-κB Pathway in MC3T3-E1 Cells

Advanced glycation end-products (AGEs) are increased under hyperglycemia in vivo and are associated with the onset of diabetes. According to previous studies, AGEs exacerbate inflammatory diseases. However, the mechanism by which AGEs aggravate osteoblast inflammation remains unknown. Therefore, the aim of this study was to determine the effects of AGEs on the production of inflammatory mediators in MC3T3-E1 cells and the underlying molecular mechanisms. Co-stimulation with AGEs and lipopolysaccharide (LPS) was found to increase the mRNA and protein levels of cyclooxygenase 2 (COX2), interleukin-1α (IL-1α), S100 calcium-binding protein A9 (S100A9), and the production of prostaglandin E2 (PGE2) compared to no stimulation (untreated control) or individual stimulation with LPS or AGEs. In contrast, the phospholipase C (PLC) inhibitor, U73122, inhibited these stimulatory effects. Co-stimulation with AGEs and LPS also increased the nuclear translocation of nuclear factor-kappa B (NF-κB) compared to no stimulation (untreated control) or individual stimulation with LPS or AGE. However, this increase was inhibited by U73122. Co-stimulation with AGEs and LPS-induced phosphorylated phospholipase Cγ1 (p-PLCγ1) and phosphorylated c-Jun N-terminal kinase (p-JNK) expression compared to no stimulation or individual stimulation with LPS or AGEs. U73122 inhibited the effects induced by co-stimulation. siPLCγ1 did not increase the expression of p-JNK and the translocation of NF-κB. Overall, co-stimulation with AGEs and LPS may promote inflammation mediators in MC3T3-E1 cells by activating the nuclear translocation of NF-κB via PLCγ1-JNK activation.

Antibacterial and Anti-Inflammatory Properties of a Novel Antimicrobial Peptide Derived from LL-37

Peri-implantitis is a pathological condition involving tissues around dental implants that are characterized by inflammation of the peri-implant mucosa and progressive loss of supporting bone. We found that the antimicrobial peptide KR-12-3 (KRIVKWIKKFLR) derived from LL-37 had antibacterial properties against Streptococcus gordonii. The purpose of this study was to evaluate its antibacterial and anti-inflammatory activities and its underlying mechanisms. We evaluated the antibacterial activities of antimicrobial peptides in planktonic and biofilm states by measuring their minimum inhibitory concentration, minimum bactericidal concentration, and biofilm susceptibility. The effects of antimicrobial peptides on the production of IL-6 and IL-8 in LPS-stimulated RAW264.7 cells were detected by enzyme-linked immunosorbent assay and other experiments, and their toxicity to MC3T3-E1 cells was also studied. While maintaining low cytotoxicity, KR-12-3 exhibited growth inhibitory effects on S. gordonii in planktonic and biofilm states. Lower concentrations of KR-12-3 treatment reduced the production of inflammatory cytokines in LPS-stimulated RAW264.8 cells. The mechanisms underlying the inhibition of biofilm formation and anti-inflammatory effects have been associated with the low expression of related genes. KR-12-3 may be used to develop an antibacterial, anti-infective, and anti-inflammatory drugs for peri-implantitis.

Erxian herbal pair enhances bone formation in infected bone nonunion models and attenuates lipopolysaccharide-induced osteoblastinhibition by regulating miRNA-34a-5p

Bacterium-induced inflammatory responses cause bone nonunion. Although antibiotics suppress infection, bone loss after antibacterial treatment remains a critical challenge. Erxian herbal pair (EHP) has been proven effective in promoting bone formation. Our study aimed to investigate the effect of EHP on bone repair after anti-infection treatment, explore its effect on a lipopolysaccharide (LPS)-induced osteoblast. We evaluated effects of EHP on bone repair with Micro-CT, and morphology detecting. Chemical constituents of EHP and EHP-containing serum (EHP-CS) were identified by UHPLC-Q/TOF-MS. In addition, osteoblast induced by LPS was established and administrated with EHP-CS. Cell proliferationwas assessed by MTT. Target prediction identified SMAD2 as a potential target of miRNA-34a-5p. MiRNA mimic, inhibitor and siRNA were transiently transfected into osteoblasts. The mRNA levels and protein expressions of miRNA-34a-5p, BMP2, Runx2, SMAD2 were assessed. The results showed that the main biocactivity ingredients in EHP-CS were Baohuoside Ι and Orcinol Glucoside. EHP could promote bone remolding after anti-infection therapy and restore the activity of LPS-induced osteoblasts. Moreover, miRNA-34a-5p was dramatically downregulated and SMAD2 was upregulated after LPS stimulation, while EHP resisted the inhibition of LPS by promoting miRNA-34a-5p, ALP, and BMP2 expressions. Whereas downregulation of miRNA-34a-5p reversed these effects. Silencing endogenous SMAD2 expression markedly promoted BMP2 and ALP activity and enhanced osteogenesis. Taken together, EHP restored LPS-induced bone loss by regulating miRNA-34a-5p levels and repressing its target gene SMAD2. EHP might be a potential adjuvant herbal remedy for the treatment of bone nonunion, and miRNA-34a-5p is a novel target for controlling bone and metabolic diseases.

Ultrasound stimulation improves inflammatory resolution, neuroprotection, and functional recovery after spinal cord injury

Spinal cord injury (SCI) is associated with limited functional recovery. Despite advances in neuroscience, realistic therapeutic treatments for SCI remain unavailable. In this study, the effects of non-invasive ultrasound (US) treatment on behavior and inflammatory responses were evaluated in a rat model of SCI. Adult female Sprague–Dawley rats were subjected to spinal cord contusion injury. Two different US parameters (SCIU5: 5% and SCIU40: 40% duty cycle) were applied, and their effects on behavioral recovery after SCI were quantified. Tissue and neuronal responses were detected. Immunofluorescence was used to detect inflammatory markers. In the rat model of SCI, motor function was more effectively restored, and the lesion cavity area was smaller in the SCIU5 group. Furthermore, the SCIU5 protocol elicited an anti-inflammatory response at the injury site by reducing degenerative FJC-labeled neurons, macrophage/microglia activation, and infiltration. Thus, the lesion area decreased, and tissue density increased. Meanwhile, the SCIU40 protocol did not improve motor function or induce an anti-inflammatory response at the injury site. The SCIU5 protocol effectively accelerated the rate of improved exercise performance in the rat model while reducing inflammation. Accordingly, appropriate US stimulation may represent a promising treatment modality for SCI with beneficial anti-inflammatory effects.

Control of inflammation using non-invasive neuromodulation: past, present and promise

The nervous system has been increasingly recognized as a novel and accessible target in the regulation of inflammation. The use of implantable and invasive devices targeting neural circuits has yielded successful results in clinical settings but does have some risk or adverse effects. Recent advances in technology and understanding of mechanistic pathways have opened new avenues of non-invasive neuromodulation. Through this review we discuss the novel research and outcomes of major modalities of non-invasive neuromodulation in the context of inflammation including transcutaneous electrical, magnetic and ultrasound neuromodulation. In addition to highlighting the scientific observations and breakthroughs, we discuss the underlying mechanisms and pathways for neural regulation of inflammation.

LIPUS inhibits inflammation and catabolism through the NF-κB pathway in human degenerative nucleus pulposus cells

Background

Low-intensity pulsed ultrasound (LIPUS) is a safe and noninvasive rehabilitative physical therapy with anti-inflammatory effects. The current study investigated the effect of LIPUS on the inflammation of nucleus pulposus (NP) cells and its underlying mechanism.

Methods

Human NP cells were acquired from lumbar disc herniation tissue samples and cultured for experiments. Human NP cells were treated with LPS and then exposed to LIPUS (15 mW/cm², 30 mW/cm² and 60 mW/cm²) for 20 min daily for 3 days to determine the appropriate intensity to inhibit the expression of the inflammatory factors TNF-α and IL-1β. The gene and protein expression of aggrecan, collagen II, MMP-3 and MMP-9 was measured by real‐time PCR and western blotting, respectively. The activity of the nuclear factor‐kappa B (NF‐κB) pathway was examined by western blotting and immunofluorescence. After pretreatment with the NF-κB inhibitor PDTC, the expression of TNF-α, IL-1β, MMP-3 and MMP-9 was measured by real‐time PCR.

Results

LIPUS at intensities of 15 mW/cm², 30 mW/cm² and 60 mW/cm² inhibited LPS-induced NP cell expression of the inflammatory factors TNF-α and IL-1β, especially at 30 mW/cm². LIPUS significantly upregulated the gene and protein expression of aggrecan and collagen II and downregulated the gene and protein expression of MMP-3 and MMP-9 in LPS-induced NP cells. The NF‐κB signaling pathway was inhibited by LIPUS through inhibiting the protein expression of p-P65 and the translocation of P65 into the nucleus in LPS-induced NP cells. In addition, LIPUS had similar effects as the NF-κB inhibitor PDTC by inhibiting the NF-κB signaling pathway, inflammation and catabolism in LPS-induced human degenerative nucleus pulposus cells.

Conclusion

LIPUS inhibited inflammation and catabolism through the NF‐κB pathway in human degenerative nucleus pulposus cells.

Irisin enhances osteogenic differentiation of mouse MC3T3-E1 cells via upregulating osteogenic genes

Osteoporosis affects millions of individuals and remains a clinical challenge in terms of prevention and treatment. The present study aimed to investigate the effect of irisin on osteogenic differentiation by exposing MC3T3-E1 cells to different concentrations of irisin. Treated cells were assayed for osteoblast proliferation and osteogenic differentiation by measuring alkaline phosphatase (ALP) activity, calcium deposition, formation of mineralized nodules and the expression of osteogenic genes using reverse transcription-quantitative PCR. The proliferation of MC3T3-E1 cells was unaffected by irisin at the concentrations tested of up to 100 ng/ml (P>0.05). ALP activity and mineralized nodule formation were significantly enhanced by irisin in a dose- and time-dependent manner, indicating that irisin promotes osteoblast differentiation of MC3T3-E1 cells. The expression of osteogenic genes, including ALP, collagen I, runt-related transcription factor 2, osterix, osteopontin, osteocalcin, osteoprotegerin and estrogen receptor α, increased significantly after irisin treatment. The present study demonstrated that irisin promoted the osteogenic differentiation of MC3T3-E1 cells, possibly by upregulating the expression of osteogenic genes and markers. Therefore, irisin may be worthy of further investigation as a potential therapeutic agent for osteoporosis.

AT1 and AT2 Receptor Knockout Changed Osteonectin and Bone Density in Mice in Periodontal Inflammation Experimental Model

BACKGROUND

The aim of this study was to evaluate the role of AT1 and AT2 receptors in a periodontal inflammation experimental model.

METHODS

Periodontal inflammation was induced by LPS/Porphyromonas gingivalis. Maxillae, femur, and vertebra were scanned using Micro-CT. Maxillae were analyzed histopathologically, immunohistochemically, and by RT-PCR.

RESULTS

The vertebra showed decreased BMD in AT1 H compared with WT H (p < 0.05). The femur showed increased Tb.Sp for AT1 H and AT2 H, p < 0.01 and p < 0.05, respectively. The Tb.N was decreased in the vertebra (WT H-AT1 H: p < 0.05; WT H-AT2 H: p < 0.05) and in the femur (WT H-AT1 H: p < 0.01; WT H-AT2 H: p < 0.05). AT1 PD increased linear bone loss (p < 0.05) and decreased osteoblast cells (p < 0.05). RANKL immunostaining was intense for AT1 PD and WT PD (p < 0.001). OPG was intense in the WT H, WT PD, and AT2 PD when compared to AT1 PD (p < 0.001). AT1 PD showed weak immunostaining for osteocalcin compared with WT H, WT PD, and AT2 PD (p < 0.001). AT1 H showed significantly stronger immunostaining for osteonectin in fibroblasts compared to AT2 H (p < 0.01).

CONCLUSION

AT1 receptor knockout changed bone density, the quality and number of bone trabeculae, decreased the number of osteoblast cells, and increased osteonectin in fibroblasts.

Functional identification of a rare vascular endothelial growth factor a (VEGFA) variant associating with the nonsyndromic cleft lip with/without cleft palate

Vascular endothelial growth factor A (VEGFA) is a crucial growth factor, which participates in multiple processes of human growth and development, such as angiogenesis and osteogenesis and is also necessary for development of palate. The purpose of this study was to investigate the effect of a rare VEGFA mutation (NM_001025366.2 773 T > C p.Val258Ala) on the cell functions and osteogenesis. Here, we found that the VEGFA mutation has adverse effects on the function of human embryonic palatal plate mesenchymal (HEPM) cells, and may affect the development of palate. The VEGFA mutation has adverse effects on promoting cell proliferation and migration and inhibiting apoptosis in HEPM and HEK–293 cells. In addition, the mutant VEGFA allele has a negative influence on osteogenesis. Taken together, the rare variant of the VEGFA gene had an adverse effect on cell functions and osteogenesis, which may impact the development of the palate. And these findings suggested that VEGFA mutation (c.773 T > C) may lead to nonsyndromic cleft lip with or without cleft palate and also provide a new insight into the mechanism of VEGFA gene in osteogenesis and palatogenesis.

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.

Application of low-intensity pulsed therapeutic ultrasound on mesenchymal precursors does not affect their cell properties

Ultrasound is considered a safe and non-invasive tool in regenerative medicine and has been used in the clinic for more than twenty years for applications in bone healing after the approval of the Exogen device, also known as low-intensity pulsed ultrasound (LIPUS). Beyond its effects on bone health, LIPUS has also been investigated for wound healing of soft tissues, with positive results for various cell processes including cell proliferation, migration and angiogenesis. As LIPUS has the potential to treat chronic skin wounds, we sought to evaluate the effects produced by a conventional therapeutic ultrasound device at low intensities (also considered LIPUS) on the migration capacity of mouse and human skin mesenchymal precursors (s-MPs). Cells were stimulated for 3 days (20 minutes per day) using a traditional ultrasound device with the following parameters: 100 mW/cm2 with 20% duty cycle and frequency of 3 MHz. At the parameters used, ultrasound failed to affect s-MP proliferation, with no evident changes in morphology or cell groupings, and no changes at the cytoskeletal level. Further, the migration and invasion ability of s-MPs were unaffected by the ultrasound protocol, and no major changes were detected in the gene/protein expression of ROCK1, integrin β1, laminin β1, type I collagen and transforming growth factor β1. Finally, RNA-seq analysis revealed that only 10 genes were differentially expressed after ultrasound stimulation. Among them, 5 encode for small nuclear RNAs and 2 encode for proteins belonging to the nuclear pore complex. Considering the results overall, while the viability of s-MPs was not affected by ultrasound stimulation and no changes were detected in proliferation/migration, RNA-seq analysis would suggest that s-MPs do respond to ultrasound. The use of 100 mW/cm2 intensity or conventional therapeutic ultrasound devices might not be optimal for the stimulation the properties of cell populations. Future studies should investigate the potential application of ultrasound using variations of the tested parameters.

Ultrasound May Suppress Tumor Growth, Inhibit Inflammation, and Establish Tolerogenesis by Remodeling Innatome via Pathways of ROS, Immune Checkpoints, Cytokines, and Trained Immunity/Tolerance

BACKGROUND

The immune mechanisms underlying low-intensity ultrasound- (LIUS-) mediated suppression of inflammation and tumorigenesis remain poorly determined.

METHODS

We used microarray datasets from the NCBI GEO DataSet repository and conducted comprehensive data-mining analyses, where we examined the gene expression of 1376 innate immune regulators (innatome genes (IGs) in cells treated with LIUS.

RESULTS

We made the following findings: (1) LIUS upregulates proinflammatory IGs and downregulates metastasis genes in cancer cells, and LIUS upregulates adaptive immunity pathways but inhibits danger-sensing and inflammation pathways and promote tolerogenic differentiation in bone marrow (BM) cells. (2) LIUS upregulates IGs encoded for proteins localized in the cytoplasm, extracellular space, and others, but downregulates IG proteins localized in nuclear and plasma membranes, and LIUS downregulates phosphatases. (3) LIUS-modulated IGs act partially via several important pathways of reactive oxygen species (ROS), reverse signaling of immune checkpoint receptors B7-H4 and BTNL2, inflammatory cytokines, and static or oscillatory shear stress and heat generation, among which ROS is a dominant mechanism. (4) LIUS upregulates trained immunity enzymes in lymphoma cells and downregulates trained immunity enzymes and presumably establishes trained tolerance in BM cells. (5) LIUS modulates chromatin long-range interactions to differentially regulate IGs expression in cancer cells and noncancer cells.

CONCLUSIONS

Our analysis suggests novel molecular mechanisms that are utilized by LIUS to induce tumor suppression and inflammation inhibition. Our findings may lead to development of new treatment protocols for cancers and chronic inflammation.

Suppression of adipocyte differentiation by low-intensity pulsed ultrasound via inhibition of insulin signaling and promotion of CCN family protein 2

Adipocyte differentiation is regulated by several transcription factors such as the CCAAT/enhancer-binding proteins (C/EBPs) and peroxisome proliferator-activated receptor-γ (PPARγ). Here, we demonstrate that low-intensity pulsed ultrasound (LIPUS) suppressed differentiation into mature adipocytes via multiple signaling pathways. When C3H10T1/2, a mesenchymal stem cell line, was treated with LIPUS (3.0 MHz, 60 mW/cm2 ) for 20 minutes once a day for 4 days during adipogenesis, and both the number of lipid droplets and the gene expression of PPARγ and C/EBPα were significantly decreased. Furthermore, LIPUS treatment decreased the phosphorylation of the insulin receptor and also that of Akt and ERK1/2, which are located downstream of this receptor. Next, we showed that LIPUS suppressed the gene expression of angiotensinogen (AGT), which is an adipokine produced by mature adipocytes, as well as that of angiotensin-converting enzyme 1 (ACE1) and angiotensin receptor type 1 (AT1 R) during adipogenesis of pre-adipogenic 3T3-L1 cells. Next, the translocation of Yes-associated protein (YAP) into the nucleus of 3T3-L1 cells was promoted by LIPUS, leading to upregulation of CCN family protein 2 (CCN2), a cellular communication network factor. Moreover, forced expression of CCN2 in 3T3-L1 cells decreased PPARγ gene expression, but it did not increase alkaline phosphatase and osterix gene expression. Finally, gene silencing of CCN2 in C3H10T1/2 cells diminished the effect of LIPUS on the gene expression of PPARγ and C/EBPα. These findings suggest that LIPUS suppressed adipogenesis through inhibition of insulin signaling and decreased PPARγ expression via increased CCN2 production, resulting in a possible decrease of mature adipocytes.

Antiarthritic Effects of a Root Extract from Harpagophytum procumbens DC: Novel Insights into the Molecular Mechanisms and Possible Bioactive Phytochemicals

Harpagophytum procumbens (Burch.) DC. ex Meisn. is a traditional remedy for osteoarticular diseases, including osteoarthritis (OA), although the bioactive constituents and mechanisms involved are yet to be clarified. In the present study, an aqueous H. procumbens root extract (HPE; containing 1.2% harpagoside) was characterized for its effects on synoviocytes from OA patients and phytochemical composition in polyphenols, and volatile compounds were detected. HPE powder was dissolved in different solvents, including deionized water (HPE_H2O), DMSO (HPE_DMSO), 100% v/v ethanol (HPE_EtOH100), and 50% v/v ethanol (HPE_EtOH50). The highest polyphenol levels were found in HPE_DMSO and HPE_EtOH50, whereas different volatile compounds, mainly β-caryophyllene and eugenol, were detected in all the extracts except for HPE_H2O. HPE_H2O and HPE_DMSO were able to enhance CB2 receptor expression and to downregulate PI-PLC β2 in synovial membranes; moreover, all the extracts inhibited FAAH activity. The present results highlight for the first time a multitarget modulation of the endocannabinoid system by HPE, likely ascribable to its hydrosoluble compounds, along with the presence of volatile compounds in H. procumbens root. Although hydrosoluble compounds seem to be mainly responsible for endocannabinoid modulation by HPE, a possible contribution of volatile compounds can be suggested, strengthening the hypothesis that the entire phytocomplex can contribute to the H. procumbens healing properties.

Effectiveness of low-intensity pulsed ultrasound on osteoarthritis of the temporomandibular joint: A review

Loading is indispensable for the growth, development, and maintenance of joint tissues, including mandibular condylar cartilage, but excessive loading or reduced host adaptive capacity can considerably damage the temporomandibular joint (TMJ), leading to temporomandibular joint osteoarthritis (TMJ-OA). TMJ-OA, associated with other pathological conditions and aging processes, is a highly degenerative disease affecting the articular cartilage. Many treatment modalities for TMJ-OA have been developed. Traditional clinical treatment includes mainly nonsurgical options, such as occlusal splints. However, non-invasive therapy does not achieve joint tissue repair and regeneration. Growing evidence suggests that low-intensity pulsed ultrasound (LIPUS) accelerates bone fracture healing and regeneration, as well as having extraordinary effects in terms of soft tissue repair and regeneration. The latter have received much attention, and various studies have been performed to evaluate the potential role of LIPUS in tissue regeneration including that applied to articular cartilage. The present article provides an overview of the status of LIPUS stimulation used to prevent the onset and progression of TMJ-OA and enhance the tissue regeneration of mandibular condylar cartilage. The etiology and management of TMJ-OA are explained briefly, animal models of TMJ-OA are described, and the effectiveness of LIPUS on cell metabolism and tissue regeneration in the TMJ is discussed.

Low-intensity pulsed ultrasound activates autophagy in periodontal ligament cells in the presence or absence of lipopolysaccharide

OBJECTIVE

This study aims to determine if low-intensity pulsed ultrasound (LIPUS) activates autophagy in human periodontal ligament cells (PDLCs) irrespective of lipopolysaccharide.

DESIGN

Six groups were designed: control, LIPUS, lipopolysaccharide, LIPUS + lipopolysaccharide, LIPUS+3-Methyladenine, LIPUS + lipopolysaccharide+3-Methyl- adenine. LIPUS pretreated PDLCs for 2 h and lipopolysaccharide treated for different times. Real-time PCR and Western-blot were performed to evaluate mRNA and protein expression levels of autophagic genes Beclin-1 and LC3 respectively. A transmission electronic microscope was used to observe the autophagosome. ELISA was used to test interleukin-6 expression.

RESULTS

Compared with the non-treatment, LIPUS pretreatment increased mRNA expression levels of LC3 (P < 0.05) and Beclin-1 (P < 0.05) at 4 h and 8 h, and enhanced the protein expression levels of LC3-Ⅱ at 8 h (P<0.05) and Beclin-1 at 4 h, 8 h and 16 h(P<0.05). After LIPUS pretreatment and lipopolysaccharide treatment for 8 h, LC3-Ⅱ and Beclin-1 protein expression levels were elevated (P < 0.05) compared with the control. Following further treatment by 3-Methyladenine, Beclin-1 protein expression was decreased (P < 0.05) compared with the LIPUS plus lipopolysaccharide group, but LC3-Ⅱ protein expression was not. Autophagosomes were not found in the LIPUS+3-Methyladenine and LIPUS+lipopolysaccharide+3-Methyladenine groups. After LIPUS pretreatment and lipopolysaccharide treatment for 36 h, intreleukin-6 expression was decreased (P<0.05) compared with the lipopolysaccharide group. However, after addition of 3-Methyladenine, intreleukin-6 expression was elevated (P < 0.05) compared with the LIPUS +lipopolysaccharide group.

CONCLUSIONS

LIPUS can promote autophagy in PDLCs irrespective of lipopolysaccharide. Autophagy might be involved in LIPUS anti-inflammatory mechanism in PDLCS.

Low-Intensity Pulsed Ultrasound Alleviates Hypoxia-Induced Chondrocyte Damage in Temporomandibular Disorders by Modulating the Hypoxia-Inducible Factor Pathway

Temporomandibular disorders are a common cause of chronic pain in the orofacial region and have a complex and multi-factorial pathophysiology. Mechanical loading or inflammatory conditions have been shown to decrease oxygen tension within the joint cartilage and activate the hypoxia-inducible factor (HIF) pathway, which in turn aggravates the pathological processes underlying temporomandibular joint (TMJ) disorders. We previously showed that low-intensity pulsed ultrasound (LIPUS) treatment effectively repairs TMJ injury induced by chronic sleep deprivation (CSD). Here, we explored the effects of LIPUS treatment on hypoxia-induced chondrocyte injury. We found that it effectively restored the proliferation capacity of mandibular chondrocytes under hypoxic conditions and lowered their rate of apoptosis. Chondrogenic capacity, as assessed by type II collagen levels, and mucin-positive areas were also significantly increased after LIPUS treatment. Levels of matrix metalloprotein-3 and interleukin-6 decreased in mandibular chondrocytes following this treatment, whereas the expression of tissue inhibitor of metalloproteinase-1 increased. We also found that HIF-1α expression was upregulated in mandibular chondrocytes under hypoxic conditions and was further enhanced by LIPUS treatment. Similarly, HIF-2α levels increased in mandibular chondrocytes under hypoxic conditions but decreased following LIPUS treatment. Subsequently, we established a CSD-induced TMJ injury model and found that LIPUS increased mucin-positive areas as well as HIF-1α expression and decreased HIF-2 level in the chondrocyte layer. Together, our results indicate that the protective effect of LIPUS on chondrocyte is partly associated with the HIF pathway.

METTL3 Regulates Osteoblast Differentiation and Inflammatory Response via Smad Signaling and MAPK Signaling

Osteoblasts are crucial bone-building cells that maintain bone homeostasis, whereas inflammatory stimuli can inhibit osteogenesis and activate inflammatory response. N6-methyladenosine (m⁶A) is the most abundant mRNA modification in eukaryotes and plays important roles in multiple biological processes. However, whether m⁶A modification affects osteoblast differentiation and inflammatory response remains unknown. To address this issue, we investigated the expression of the N6-adenosine methyltransferase METTL3 and found that it was upregulated during osteoblast differentiation and downregulated after LPS stimulation. We then knocked down METTL3 and observed decreased levels of osteogenic markers, ALP activity, and mineralized nodules, as well as Smad1/5/9 phosphorylation, in LPS-induced inflammation. METTL3 knockdown promoted the mRNA expression and stability of negative regulators of Smad signaling, Smad7 and Smurf1, the same regulatory pattern identified when the m⁶A-binding protein YTHDF2 was silenced. Moreover, METTL3 depletion enhanced proinflammatory cytokine expression and increased the phosphorylation of ERK, p38, JNK, and p65 in MAPK and NF-κB signaling pathways. The increase in cytokine expression was inhibited after MAPK signaling inhibitor treatment. All data suggest that METTL3 knockdown inhibits osteoblast differentiation and Smad-dependent signaling by stabilizing Smad7 and Smurf1 mRNA transcripts via YTHDF2 involvement and activates the inflammatory response by regulating MAPK signaling in LPS-induced inflammation.

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

Synovitis is implicated in the pathology of osteoarthritis (OA) and significantly contributes to the development of OA. As a noninvasive physical therapy, low-intensity pulsed ultrasound (LIPUS) has been reported to possess anti-inflammatory effect in recent years. However, the role of LIPUS on synovitis of OA and the underlying mechanisms are little known. The present study showed that LIPUS ameliorated synovial inflammation in destabilization of the medial meniscus (DMM) mouse model and air pouch model, and alleviated pain gait patterns of DMM mouse. LIPUS dramatically inhibited the production of mature IL1B/IL-1β (interleukin 1 beta) in vitro and in vivo. In addition, LIPUS upregulated the macroautophagy/autophagy level as well as accelerated the formation of an SQSTM1 (sequestosome1)-PKM (pyruvate kinase, muscle) complex in the lipopolysaccharide (LPS)-adenosine triphosphate (ATP)-treated macrophages. Besides, LIPUS downregulated the level of PKM2 in LPS-ATP-treated macrophages, which could be reversed by SQSTM1 knockdown. In brief, the present study for the first time demonstrates that LIPUS inhibits the production of mature IL1B partially via SQSTM1-dependent autophagic degradation of PKM2 in LPS-ATP-treated macrophages, which may further ameliorate the synovial inflammation and gait patterns in animal models. Our data provide new clues for the treatments of synovitis and other inflammatory diseases using LIPUS.

ABBREVIATIONS

3-MA: 3-methyladenene; ATG7: autophagy-related 7; ATP: adenosine triphosphate; BafA1: bafilomycin A₁; BMDMs: bone marrow derived macrophages; CHX: cycloheximide; DMM: destabilization of the medial meniscus; ELISA: enzyme-linked immunosorbent assay; GFP: green fluorescent protein; IL1B/IL-1β: interleukin 1 beta; LIPUS: low-intensity pulsed ultrasound; LIR: LC3-interacting region; LPS: lipopolysaccharide; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MDP: muramyl dipeptide; NFKB/NF-κB: nuclear factor kappa B; NLRP3: NLR family, pyrin domain containing 3; OA: osteoarthritis; PKM/PKM2: pyruvate kinase M1/2; PMA: phorbol-12-myristate-13-acetate; PYCARD/ASC; PYD and CARD domain containing; RFP: red fluorescent protein; siRNAs: small interfering RNAs; SQSTM1: sequestosome 1; TEM: transmission electron microscopy.

LIPUS inhibited the expression of inflammatory factors and promoted the osteogenic differentiation capacity of hPDLCs by inhibiting the NF-κB signaling pathway

BACKGROUND AND OBJECTIVES

As a chronic infectious disease, periodontitis could lead to tooth and bone loss. Low-intensity pulsed ultrasound (LIPUS) is a safe, noninvasive treatment method to effectively inhibit inflammation and promote bone differentiation. However, the application of LIPUS in curing periodontitis is still rare. Our study aimed to explore the ability of LIPUS to inhibit inflammatory factors and promote the osteogenic differentiation capacity of human periodontal ligament cells (hPDLCs), and its underlying mechanism.

MATERIAL AND METHODS

Human periodontal ligament cells were obtained and cultured from the premolar tissue samples for experiments. First, hPDLCs were treated for 24 hours using lipopolysaccharide (LPS) and then exposed to LIPUS (10 mW/cm² , 30 mW/cm² , 60 mW/cm² , and 90 mW/cm² ) to determine the appropriate intensity to inhibit expression of the inflammatory factors interleukin-6 (IL-6) and interleukin-8 (IL-8) expression. The expression of IL-6 and IL-8 was detected by real-time PCR and enzyme-linked immunosorbent assay. The safety of the most appropriate intensity of LIPUS was tested by a cell counting kit 8 test and an apoptosis assay. Then, LPS-induced hPDLCs were treated in osteogenic medium for 7-21 days with or without LIPUS (90 mW/cm² , 30 min/d) stimulation. The osteogenic genes RUNX2, OPN, OSX, and OCN were measured by real-time PCR. Additionally, osteogenic differentiation capacity was determined using alkaline phosphatase (ALP) staining, ALP activity analysis, and Alizarin red staining. The activity of the nuclear factor-kappa B (NF-κB) signaling pathway was determined by western blotting, real-time PCR, immunofluorescence, and pathway blockade assays.

RESULTS

Lipopolysaccharide significantly upregulated the production and gene expression of IL-6 and IL-8, while LIPUS stimulation significantly inhibited IL-6 and IL-8 expression in an intensity-dependent manner. LIPUS (90 mW/cm² ) was chosen as the most appropriate intensity, and there was no detrimental influence on cell proliferation and status with or without osteogenic medium. In addition, consecutive stimulation with LIPUS (90 mW/cm² ) for 30 min/d for 7 days could also inhibit IL-6 and IL-8 gene expression, upregulate the expression of the osteogenesis-related genes RUNX2, OPN, OSX, and OCN, and promote osteogenic differentiation capacity in osteogenic medium in inflamed hPDLCs. The NF-κB signaling pathway was inhibited with LIPUS (90 mW/cm² ) via inhibition of the phosphorylation of IκBα and the translocation of p65 into the nucleus in inflamed hPDLCs. Additional investigations of the NF-κB inhibitor, BAY 11-7082, revealed that LIPUS (90 mW/cm² ) acted similarly to BAY 11-7802 to inhibit the NF-κB signaling pathway and increase osteogenesis-related genes and promote the osteogenic differentiation capacity of inflamed hPDLCs.

CONCLUSION

Low-intensity pulsed ultrasound (90 mW/cm² ) stimulation could be a safe method to inhibit IL-6 and IL-8 in hPDLCs by inhibiting the NF-κB signaling pathway. The effect of LIPUS (90 mW/cm² ) and BAY 11-7082 on LPS-induced inflammation demonstrated that both of these agents were capable of promoting osteogenesis-related gene expression and osteogenic differentiation in hPDLCs, suggesting that the effect of LIPUS on the promotion of osteogenic activity could be mediated in part through its ability to inhibit the NF-κB signal pathway. Hence, LIPUS could be a potential therapeutic method to cure periodontitis.

Exosomes Derived From Low-Intensity Pulsed Ultrasound-Treated Dendritic Cells Suppress Tumor Necrosis Factor-Induced Endothelial Inflammation

OBJECTIVES

Endothelial cell inflammation plays an important role in atherosclerosis. Low-intensity pulsed ultrasonography (LIPUS) exerts an anti-inflammatory function on endothelial cells, whereas the underlying mechanism has not been fully elucidated.

METHODS

Bone marrow dendritic cells (BMDCs) derived from bone barrow cells were treated with LIPUS, and exosomes secreted into the supernatant were purified. The isolated exosomes were incubated with human umbilical vein endothelial cells (HUVECs) to investigate their effect on tumor necrosis factor (TNF)-α-induced endothelial inflammation. Ultrastructure was analyzed by transmission electron microscopy. Messenger RNA levels were determined by quantitative reverse transcription polymerase chain reaction, and protein levels were analyzed by western blot.

RESULTS

The isolated exosomes presented a typical exosomal size of 30 to 100 nm in diameter and expressed exosome positive markers (Alix, CD63, and TSG101) but not the exosome negative marker (Calnexin). Exosomes derived from LIPUS-treated BMDCs were rich in miR-16 and miR-21, which could be engulfed by HUVECs. Pretreatment with exosomes impeded TNFα-induced HUVEC activation and downregulated TNFα-stimulated expression of vascular cell adhesion molecule-1 and intercellular adhesion molecule-1, thus preventing TNFα-induced activation of the nuclear factor-κB signaling pathway.

CONCLUSION

Exosomes derived from LIPUS-treated BMDC inhibit TNFα-induced endothelial inflammation by inhibiting the nuclear factor-κB signaling pathway.

Experimental Data-Mining Analyses Reveal New Roles of Low-Intensity Ultrasound in Differentiating Cell Death Regulatome in Cancer and Non-cancer Cells via Potential Modulation of Chromatin Long-Range Interactions

Background: The mechanisms underlying low intensity ultrasound (LIUS) mediated suppression of inflammation and tumorigenesis remain poorly determined. Methods: We used microarray datasets from NCBI GEO Dataset databases and conducted a comprehensive data mining analyses, where we studied the gene expression of 299 cell death regulators that regulate 13 different cell death types (cell death regulatome) in cells treated with LIUS. Results: We made the following findings: (1) LIUS exerts a profound effect on the expression of cell death regulatome in cancer cells and non-cancer cells. Of note, LIUS has the tendency to downregulate the gene expression of cell death regulators in non-cancer cells. Most of the cell death regulator genes downregulated by LIUS in non-cancer cells are responsible for mediating inflammatory signaling pathways; (2) LIUS activates different cell death transcription factors in cancer and non-cancer cells. Transcription factors TP-53 and SRF- were induced by LIUS exposure in cancer cells and non-cancer cells, respectively; (3) As two well-accepted mechanisms of LIUS, mild hyperthermia and oscillatory shear stress induce changes in the expression of cell death regulators, therefore, may be responsible for inducing LIUS mediated changes in gene expression patterns of cell death regulators in cells; (4) LIUS exposure may change the redox status of the cells. LIUS may induce more of antioxidant effects in non-cancer cells compared to cancer cells; and (5) The genes modulated by LIUS in cancer cells have distinct chromatin long range interaction (CLRI) patterns to that of non-cancer cells. Conclusions: Our analysis suggests novel molecular mechanisms that may be utilized by LIUS to induce tumor suppression and inflammation inhibition. Our findings may lead to development of new treatment protocols for cancers and chronic inflammation.

Bone function, dysfunction and its role in diseases including critical illness

The skeleton is one of the largest organs in the human body. In addition to its conventional functions such as support, movement and protection, the skeleton also contributes to whole body homeostasis and maintenance of multiple important non-bone organs/systems (extraskeletal functions). Both conventional and extraskeletal functions of the skeleton are defined as bone function. Bone-derived factors (BDFs) are key players regulating bone function. In some pathophysiological situations, including diseases affecting bone and/or other organs/systems, the disorders of bone itself and the subsequently impaired functions of extraskeletal organs/systems caused by abnormal bone (impaired extraskeletal functions of bone) are defined as bone dysfunction. In critical illness, which is a health status characterized by the dysfunction or severe damage of one or multiple important organs or systems, the skeleton shows rapid bone loss resulting from bone hyper-resorption and impaired osteoblast function. In addition, the dysfunctions of the skeleton itself are also closely related to the severity and prognosis of critical illness. Therefore, we propose that there is bone dysfunction in critical illness. Some methods to inhibit osteoclast activity or promote osteoblast function by the treatment of bisphosphonates or PTH1-34 benefit the outcome of critical illness, which indicates that enhancing bone function may be a potential novel strategy to improve prognosis of diseases including critical illness.

Monotropein attenuates ovariectomy and LPS-induced bone loss in mice and decreases inflammatory impairment on osteoblast through blocking activation of NF-κB pathway

Estrogen deficiency and inflammation are known to play important roles in bone metabolism and occurrence of osteoporosis. Monotropein as an iridoid glycoside is reported to decrease estrogen deficiency-induced bone loss and inhibit inflammatory response in LPS-induced RAW 264.7 macrophages. However, the effect of monotropein on bone loss in chronic inflammatory conditions remains unclear. It was found in the present study that monotropein significantly inhibited bone mass reduction and improved bone micro-architectures by enhancing bone formation and blocking increased secretion of inflammatory cytokines in osteoporotic mice induced by combined ovariectomy and LPS. Our in vitro experiment further demonstrated that monotropein was able to increase the proliferation and activity of alkaline phosphatase (ALP), bone matrix mineralization and the expression of bone matrix protein osteopontin (OPN) in osteoblastic MC3T3-E1 cells injured by LPS. In addition, monotropein significantly decreased the production of IL-6 and IL-1β, inhibited the nuclear translocation of p65 and NF-κB P50, and down-regulated the phosphorylation of NF-κB p65 and IKK, indicating that monotropein could attenuate inflammatory impairment to MC3T3-E1 cells by suppressing the activation of NF-κB pathway. All these results suggest that monotropein may prove to be a promising candidate for the prevention and treatment of inflammatory bone loss.

Resveratrol Attenuates Lipopolysaccharides (LPS)-Induced Inhibition of Osteoblast Differentiation in MC3T3-E1 Cells

Background

LPS-inhibited osteoblastic differentiation plays an important role in the pathogenesis of osteomyelitis. Thus, searching for drugs that affect LPS-mediated osteoblastic differentiation may be crucial in developing therapies for osteomyelitis. The purpose of this study was to investigate the role and mechanisms of resveratrol, a natural polyphenol present in red wine, on LPS-inhibited osteoblastic differentiation.

Material/Methods

Cell viability was measured by MMT assay. Mitochondrial ATP levels, membrane potential, and superoxide production were measured to evaluate the effects of LPS and resveratrol on mitochondrial functions in osteoblast-like MC3T3-E1 cells. Osteoblast-related genes, including ALP, OCN, OPN, and RUNX2, were measured by ELISA analysis and RT-PCR in differentiated osteoblast cells treated with LPS and resveratrol. Cellular Sirt1 and PCG-1α levels were measured by Western blot to probe the impact of resveratrol treatment in LPS-stimulated MC3T3-E1 osteoblasts.

Results

The results showed that LPS caused significant mitochondrial dysfunctions of MC3T3-E1 cells in a dose-dependent manner, which were attenuated by resveratrol. Furthermore, LPS markedly decreased the expression of ALP, OCN, OPN, and RUNX2 in MC3T3-E1 cells cultivated in osteoblast differentiation medium, suggesting that LPS inhibited the osteoblastic differentiation of MC3T3-E1 cells. However, resveratrol obviously alleviated the suppressive impact of LPS on osteoblast differentiation. In addition, resveratrol increased expression of Sirt1 and PGC-1α in MC3T3-E1 cells treated with LPS.

Conclusions

Taken together, these results show that resveratrol alleviated the suppression of LPS on osteoblast differentiation by improving, at least in part, mitochondrial function.

Low-Intensity Ultrasound-Induced Anti-inflammatory Effects Are Mediated by Several New Mechanisms Including Gene Induction, Immunosuppressor Cell Promotion, and Enhancement of Exosome Biogenesis and Docking

Background: Low-intensity ultrasound (LIUS) was shown to be beneficial in mitigating inflammation and facilitating tissue repair in various pathologies. Determination of the molecular mechanisms underlying the anti-inflammatory effects of LIUS allows to optimize this technique as a therapy for the treatment of malignancies and aseptic inflammatory disorders. Methods: We conducted cutting-edge database mining approaches to determine the anti-inflammatory mechanisms exerted by LIUS. Results: Our data revealed following interesting findings: (1) LIUS anti-inflammatory effects are mediated by upregulating anti-inflammatory gene expression; (2) LIUS induces the upregulation of the markers and master regulators of immunosuppressor cells including MDSCs (myeloid-derived suppressor cells), MSCs (mesenchymal stem cells), B1-B cells and Treg (regulatory T cells); (3) LIUS not only can be used as a therapeutic approach to deliver drugs packed in various structures such as nanobeads, nanospheres, polymer microspheres, and lipidosomes, but also can make use of natural membrane vesicles as small as exosomes derived from immunosuppressor cells as a novel mechanism to fulfill its anti-inflammatory effects; (4) LIUS upregulates the expression of extracellular vesicle/exosome biogenesis mediators and docking mediators; (5) Exosome-carried anti-inflammatory cytokines and anti-inflammatory microRNAs inhibit inflammation of target cells via multiple shared and specific pathways, suggesting exosome-mediated anti-inflammatory effect of LIUS feasible; and (6) LIUS-mediated physical effects on tissues may activate specific cellular sensors that activate downstream transcription factors and signaling pathways. Conclusions: Our results have provided novel insights into the mechanisms underlying anti-inflammatory effects of LIUS, and have provided guidance for the development of future novel therapeutic LIUS for cancers, inflammatory disorders, tissue regeneration and tissue repair.