Mechanisms underlying the antiapoptotic and anti-inflammatory effects of monotropein in hydrogen peroxide-treated osteoblasts

Human Osteoblasts' Response to Biomaterials for Subchondral Bone Regeneration in Standard and Aggressive Environments

Osteochondral lesions, when not properly treated, may evolve into osteoarthritis (OA), especially in the elderly population, where altered joint function and quality are usual. To date, a collagen/collagen-magnesium-hydroxyapatite (Col/Col-Mg-HAp) scaffold (OC) has demonstrated good clinical results, although suboptimal subchondral bone regeneration still limits its efficacy. This study was aimed at evaluating the in vitro osteogenic potential of this scaffold, functionalized with two different strategies: the addition of Bone Morphogenetic Protein-2 (BMP-2) and the incorporation of strontium (Sr)-ion-enriched amorphous calcium phosphate (Sr-ACP) granules. Human osteoblasts were seeded on the functionalized scaffolds (OC+BMP-2 and OC+Sr-ACP, compared to OC) under stress conditions reproduced with the addition of H2O2 to the culture system, as well as in normal conditions, and evaluated in terms of morphology, metabolic activity, gene expression, and matrix synthesis. The OC+BMP-2 scaffold supported a better osteoblast morphology and stimulated scaffold colonization, cell activity, and extracellular matrix secretion, especially in the stressed culture environment but also in normal culture conditions, with increased expression of genes related to osteoblast differentiation. In conclusion, the incorporation of BMP-2 into the Col/Col-Mg-HAp scaffold also represents an improvement of the osteochondral scaffold in more challenging conditions, supporting further preclinical studies to optimize it for use in clinical practice.

Monotropein alleviates sepsis-elicited acute lung injury via the NF-κB pathway

OBJECTIVES

To address the effect and mechanism of Monotropein (Mon) on sepsis-induced acute lung injury (ALI).

METHODS

ALI model was established by lipopolysaccharide (LPS)-stimulated mouse lung epithelial cell lines (MLE-12) and cecal ligation and puncture (CLP)-treated mice, respectively. The function of Mon was examined by cell counting kit-8 (CCK-8), pathological staining, the pulmonary function examination, flow cytometry, enzyme-linked immunosorbent assay, terminal deoxynucleotidyl transferase deoxyuridine triphosphate nick end labellingand western blot.

RESULTS

Mon increased the LPS-reduced viability but decreased the LPS-evoked apoptosis rate in MLE-12 cells. Mon suppressed the concentrations and protein expressions of proinflammatory factors, and the expressions of fibrosis-related proteins in LPS-challenged MLE-12 cells compared with LPS treatment alone. Mechanically, Mon downregulated the levels of NF-κB pathway, which was confirmed with the application of the receptor activator of nuclear factor-κB ligand (RANKL). Correspondingly, RANKL reversed the ameliorative effect of Mon on the proliferation, apoptosis, inflammation and fibrosis. Moreover, Mon improved the pathological manifestations, apoptosis, the W/D ratio and pulmonary function indicators in CLP-treated mice. Consistently, Mon attenuated inflammation, fibrosis and NF-κB pathway in CLP-treated mice.

CONCLUSION

Mon inhibited apoptosis, inflammation and fibrosis to alleviate sepsis-evoked ALI via the NF-κB pathway.

Monotropein: A comprehensive review of biosynthesis, physicochemical properties, pharmacokinetics, and pharmacology

Monotropein, a principal natural compound in iridoid glycosides extracted from Morindae officinalis radix, has potent pharmacological activities. To understand and utilize monotropein, we systematically summarized the studies on monotropein, including its biosynthetic pathway, physicochemical properties, pharmacokinetics, and pharmacology. Interestingly, we found that the multiple bioactivities of monotropein, such as anti-osteoporosis, anti-inflammation, anti-oxidation, anti-nociception, and hepatic or renal protection, are closely associated with its capability of downregulating the nuclear factor-κB signaling pathway, inhibiting the mitogen-activated protein kinase signaling pathway, attenuating the activation of nuclear factor E2-related factor 2/heme oxygenase-1 signaling pathway, and regulating the mammalian target of rapamycin/autophagy signaling pathway. However, the clinically therapeutic effects and the potential problems need to be addressed. This review highlights the current research progress on monotropein, which provides a reference for further investigation of monotropein.

Monoterpenes as Sirtuin-1 Activators: Therapeutic Potential in Aging and Related Diseases

Sirtuin 1 (SIRT) is a class III, NAD+-dependent histone deacetylase that also modulates the activity of numerous non-histone proteins through deacylation. SIRT1 plays critical roles in regulating and integrating cellular energy metabolism, response to stress, and circadian rhythm by modulating epigenetic and transcriptional regulation, mitochondrial homeostasis, proteostasis, telomere maintenance, inflammation, and the response to hypoxia. SIRT1 expression and activity decrease with aging, and enhancing its activity extends life span in various organisms, including mammals, and improves many age-related diseases, including cancer, metabolic, cardiovascular, neurodegenerative, respiratory, musculoskeletal, and renal diseases, but the opposite, that is, aggravation of various diseases, such as some cancers and neurodegenerative diseases, has also been reported. Accordingly, many natural and synthetic SIRT1 activators and inhibitors have been developed. Known SIRT1 activators of natural origin are mainly polyphenols. Nonetheless, various classes of non-polyphenolic monoterpenoids have been identified as inducers of SIRT1 expression and/or activity. This narrative review discusses current information on the evidence that supports the role of those compounds as SIRT1 activators and their potential both as tools for research and as pharmaceuticals for therapeutic application in age-related diseases.

Pro-Inflammatory Signalling PRRopels Cisplatin-Induced Toxicity

Cisplatin is a platinum-based chemotherapeutic that has long since been effective against a variety of solid-cancers, substantially improving the five-year survival rates for cancer patients. Its use has also historically been limited by its adverse drug reactions, or cisplatin-induced toxicities (CITs). Of these reactions, cisplatin-induced nephrotoxicity (CIN), cisplatin-induced peripheral neuropathy (CIPN), and cisplatin-induced ototoxicity (CIO) are the three most common of several CITs recognised thus far. While the anti-cancer activity of cisplatin is well understood, the mechanisms driving its toxicities have only begun to be defined. Most of the literature pertains to damage caused by oxidative stress that occurs downstream of cisplatin treatment, but recent evidence suggests that the instigator of CIT development is inflammation. Cisplatin has been shown to induce pro-inflammatory signalling in CIN, CIPN, and CIO, all of which are associated with persisting markers of inflammation, particularly from the innate immune system. This review covered the hallmarks of inflammation common and distinct between different CITs, the role of innate immune components in development of CITs, as well as current treatments targeting pro-inflammatory signalling pathways to conserve the use of cisplatin in chemotherapy and improve long-term health outcomes of cancer patients.

Melatonin alleviates hydrogen peroxide induced oxidative damage in MC3T3-E1 cells and promotes osteogenesis by activating SIRT1

Oxidative stress is an important contributor to the development of osteoporosis. Melatonin, an indoleamine secreted by the pineal gland, has antioxidant properties. This study aims to explore whether melatonin can promote bone formation and elucidate the mechanisms underlying this process. In this study, we used an in vitro hydrogen peroxide (H₂O₂)-induced oxidative stress model in MC3T3-E1 cells and an in vivo ovariectomized osteoporotic bone defect model in rats to explore the protective effects of melatonin against osteoporotic bone defects along with the mechanism underlying these effects. We found that melatonin significantly increased alkaline phosphatase activity, mineralization capacity, and the expression of BMP2, RUNX2, and OPN in MC3T3-E1 cells treated with H₂O₂. Furthermore, melatonin was found to activate SIRT1, SIRT3 and inhibit p66Shc, reduce the intracellular reactive oxygen species levels, stabilize mitochondria, reduce malondialdehyde levels, increase superoxide dismutase activity, and reduce apoptosis in MC3T3-E1 cells treated with H₂O₂. Intriguingly, these effects could be reversed by the SIRT1 inhibitor EX527. In vivo experiments confirmed that melatonin improves the microstructure and bone mineral density of the distal femoral bone trabecula and promotes bone formation. Meanwhile, melatonin activated SIRT1, inhibited p66Shc and increased SIRT3 expression. Taken together, our findings showed that melatonin can restrain oxidative damage in MC3T3-E1 cells and promote osteogenesis by activating SIRT1 which regulate the activity of SIRT3 and inhibit the expression of p66Shc, suggesting that melatonin could be a potential therapeutic agent for osteoporosis-related bone metabolic diseases.

Monotropein alleviates H2O2‑induced inflammation, oxidative stress and apoptosis via NF‑κB/AP‑1 signaling

Aging is a major risk factor in cardiovascular disease (CVD). Oxidative stress and inflammation are involved in the pathogenesis of CVD, and are closely associated with senescent vascular endothelial cells. Monotropein (Mtp) exerts various bioactive roles, including anti‑inflammatory and antioxidative effects. The aim of the present study was to investigate the function of Mtp in senescent endothelial cells. An MTT assay was performed to evaluate the influence of Mtp on H2O2‑stimulated human umbilical vein endothelial cells (HUVECs). Senescent cells were assessed by determining the expression of senescence‑associated β‑galactosidase, high mobility group AT‑hook 1 and DNA damage marker γ‑H2A.X variant histone. Malondialdehyde (MDA), superoxide dismutase (SOD), glutathione peroxidase (GSH‑Px) and proinflammatory cytokine concentrations were estimated using assay kits to evaluate the levels of oxidative stress and inflammation in HUVECs. The TUNEL assay was performed to identify apoptotic cells. Furthermore, the expression levels of endothelial cell adhesion factors, NF‑κB, activator protein‑1 (AP‑1) and apoptotic proteins were determined via western blotting. Mtp enhanced HUVEC viability following H2O2 stimulation. H2O2‑mediated increases in MDA, proinflammatory cytokine and endothelial cell adhesion factor levels were decreased by Mtp treatment, whereas Mtp reversed H2O2‑mediated downregulation of SOD and GSH‑Px activity. Furthermore, Mtp inhibited cell apoptosis, NF‑κB activation and AP‑1 expression in H2O2‑stimulated HUVECs; however, NF‑κB activator counteracted the anti‑inflammatory, antioxidative and antiapoptotic effects of Mtp. The present study indicated that Mtp ameliorated H2O2‑induced inflammation and oxidative stress potentially by regulating NF‑κB/AP‑1.

The effect of monotropein on alleviating cisplatin-induced acute kidney injury by inhibiting oxidative damage, inflammation and apoptosis

Although cisplatin is a common drug in the treatment of malignant tumors, its clinical application is limited due to various side effects, especially acute kidney injury (AKI). Till now, few effective pharmacological strategies can be applied to inhibit cisplatin-induced AKI. Here, we aimed to investigate the protective effects and possible mechanisms of monotropein on cisplatin-induced AKI. In this study, an AKI model was established in cisplatin-treated mice, and serum level of inflammatory cytokines, protein expressions of biochemical indicators and renal pathology were analyzed. Our results showed that our results showed that monotropein could significantly attenuate cisplatin-induced nephrotoxicity and reduce the levels of blood urea nitrogen (BUN) and serum creatinine (CRE). Furthermore, monotropein inhibited cisplatin-induced oxidative stress by reducing MDA level and increasing the activities of GSH, SOD and CAT. The underlying mechanisms of monotropein on alleviating cisplatin-induced AKI were associated with the activation of Nrf2/HO-1 pathway against oxidative stress and the inhibition on NF-κB signaling to suppress inflammation as well as the regulation on the expressions of proteins in apoptosis pathway in this renal injury model. This study firstly provided the evidence that monotropein could significantly attenuate cisplatin-induced AKI and suggested that monotropein might be used as a potential agent to alleviate side effects of cisplatin.

The PI3K/Akt and NF-κB signaling pathways are involved in the protective effects of Lithocarpus polystachyus (sweet tea) on APAP-induced oxidative stress injury in mice

Acetaminophen (APAP)-induced acute liver injury (ALI) is a health issue that has gradually attracted attention, and is often regarded as a model of drug-induced hepatotoxicity. The leaves of Lithocarpus polystachyus Rehd. (named as “sweet tea”, ST) usually serve as tea drink and folk medicine for healthcare in the southwest part of China. In previous reports, it has been proven to protect various animal models, except for APAP-induced liver injury model. Therefore, this study initially explored the protective effect of ST leaf extract (STL-E) on hepatotoxicity induced by APAP in ICR mice. STL-E of 50 and 100 mg kg⁻¹ were given to each group for 7 days. ALI was intraperitoneally induced by APAP treatment (i.p. 250 mg per kg body weight). Biochemical markers, levels of inflammatory factors, histopathological staining and western blotting were used to analyze the inflammation and apoptosis of liver tissues. Interestingly, the treatment with STL-E significantly attenuated APAP-induced liver injury (p < 0.05). Moreover, STL-E partially mitigated APAP-induced liver injury by effectively activating the PI3K/Akt pathway and inhibiting the NF-κB pathway. In a word, STL-E protected liver against APAP-induced hepatotoxicity by inhibiting the PI3K/Akt-mediated apoptosis signal pathway and inhibiting the NF-κB-mediated signaling pathway.

Acetaminophen (APAP)-induced acute liver injury (ALI) is a health issue that has gradually attracted attention, and is often regarded as a model of drug-induced hepatotoxicity.

Monotropein attenuates oxidative stress via Akt/mTOR-mediated autophagy in osteoblast cells

Oxidative stress is a crucial pathogenic factor in osteoporosis. Autophagy is a cellular self-digestion process that can selectively remove damaged organelles under oxidative stress, and thus presents a potential therapeutic target against osteoporosis. Monotropein is an iridoid glycoside which can increase osteoblastic bone formation and be applied for medicinal purpose in China. The aim of this work is to investigate whether autophagy participates the protection effects of monotropein in osteoblasts under oxidative stress and the possible mechanism of such involvement. Here, monotropein was capable of inhibiting the H₂O₂-induced reactive oxygen species generation in osteoblasts. Monotropein induced autophagy and protected osteoblasts from cytotoxic effects of H₂O₂, as assessed by viability assays, apoptosis and western blotting. Moreover, it significantly attenuated H₂O₂-evoked oxidative stress as measured by malondialdehyde, catalase, and superoxide dismutase levels. Importantly, monotropein reduced the phosphorylation of protein kinase B (Akt), mammalian target of rapamycin (mTOR) and its two downstream proteins (p70S6K and 4EBP1). The autophagy level increased in osteoblasts treated with monotropein as represented by an increased in both Beclin1 expression and the LC3-II/LC3-I ratio. However, the Akt activator (SC79) and mTOR activator (MHY1485) suppressed the autophagy level induced by monotropein in H₂O₂-treated cells. Consequently, the antioxidant effects of monotropein were mediated, at least in part, by enhancing autophagy through the Akt/mTOR pathway. These results suggested that monotropein might be a promising candidate for osteoporosis treatment.

The Evidence Behind Peroxide in Orthopedic Surgery

Peroxide is a strong oxidizing agent and disinfectant frequently used in orthopedic surgery. The authors conducted a systematic literature review of peroxide in orthopedic surgery, evaluating use, complications, efficacy, and appropriate concentrations. One hundred seventy-five reports were identified, with 24 being eligible for analysis. Orthopedic surgeons used peroxide for irrigation and bacterial reduction in various procedures. Complications included cytotoxicity, allergic reactions, suture damage, and inflammation. Use of the standard concentration of 3% peroxide and standard time in situ are without evidence. Laboratory studies suggest that diluted concentrations retain the benefit of bacterial decolonization without increasing the risk for complications. [Orthopedics. 2018; 41(6):e756-e764.].

Monotropein promotes angiogenesis and inhibits oxidative stress-induced autophagy in endothelial progenitor cells to accelerate wound healing

Attenuating oxidative stress‐induced damage and promoting endothelial progenitor cell (EPC) differentiation are critical for ischaemic injuries. We suggested monotropein (Mtp), a bioactive constituent used in traditional Chinese medicine, can inhibit oxidative stress‐induced mitochondrial dysfunction and stimulate bone marrow‐derived EPC (BM‐EPC) differentiation. Results showed Mtp significantly elevated migration and tube formation of BM‐EPCs and prevented tert‐butyl hydroperoxide (TBHP)‐induced programmed cell death through apoptosis and autophagy by reducing intracellular reactive oxygen species release and restoring mitochondrial membrane potential, which may be mediated viamTOR/p70S6K/4EBP1 and AMPK phosphorylation. Moreover, Mtp accelerated wound healing in rats, as indicated by reduced healing times, decreased macrophage infiltration and increased blood vessel formation. In summary, Mtp promoted mobilization and differentiation of BM‐EPCs and protected against apoptosis and autophagy by suppressing the AMPK/mTOR pathway, improving wound healing in vivo. This study revealed that Mtp is a potential therapeutic for endothelial injury‐related wounds.