Thymosin β4 Reduces H₂O₂ Induced Oxidative Stress in MC3T3-E1 Cells on Titanium Surface

Enhancing osteogenic potential of hDPSCs by resveratrol through reducing oxidative stress via the Sirt1/Nrf2 pathway

CONTEXT

The osteogenic potential of the human dental pulp stromal cells (hDPSCs) was reduced in the state of oxidative stress. Resveratrol (RSV) possesses numerous biological properties, including osteogenic potential, growth-promoting and antioxidant activities.

OBJECTIVE

This study investigates the osteogenic potential of RSV by activating the Sirt1/Nrf2 pathway on oxidatively stressed hDPSCs and old mice.

MATERIALS AND METHODS

The hDPSCs were subjected to reactive oxygen species (ROS) fluorescence staining, cell proliferation assay, ROS activity assay, superoxide dismutase (SOD) enzyme activity, the glutathione (GSH) concentration assay, alkaline phosphatase staining, real-time polymerase chain reaction (RT-PCR) and Sirt1 immunofluorescence labelling to assess the antioxidant stress and osteogenic ability of RSV. Forty female Kunming mice were divided into Old, Old-RSV, Young and Young-RSV groups to assess the repair of calvarial defects of 0.2 mL RSV of 20 mg/kg/d for seven days by injecting intraperitoneally at 4 weeks after surgery using micro-computed tomography, nonlinear optical microscope and immunohistochemical analysis.

RESULTS

RSV abates oxidative stress by alleviating the proliferation, mitigating the ROS activity, increasing the SOD enzyme activity and ameliorating the GSH concentration (RSV IC₅₀ in hDPSCs is 67.65 ± 9.86). The antioxidative stress and osteogenic capabilities of RSV were confirmed by the up-regulated gene expression of SOD1, xCT, RUNX2 and OCN, as well as Sirt1/Nrf2. The collagen, bone matrix formation and Sirt1 expression, are significantly increased after RSV treatment in mice.

DISCUSSION AND CONCLUSIONS

For elderly or patients with oxidative stress physiological states such as hypertension, heart disease, diabetes, etc., RSV may potentially improve bone augmentation surgery in regenerative medicine.

Hypermethylation of thymosin β4 predicts a poor prognosis for patients with acute-on-chronic hepatitis B liver failure

BACKGROUND

It has been demonstrated that thymosin β4 (Tβ4) could inflect the severity of acute-on-chronic hepatitis B liver failure (ACHBLF), but the relationship between its methylation status and the prognosis of liver failure is not clear. This study aimed to determine Tβ4 promoter methylation status in patients with ACHBLF and to evaluate its prognostic value.

METHODS

The study recruited 115 patients with ACHBLF, 80 with acute-on-chronic hepatitis B pre-liver failure (pre-ACHBLF), and 86 with chronic hepatitis B (CHB). In addition, there were 36 healthy controls (HCs) from the Department of Hepatology, Qilu Hospital of Shandong University. The 115 patients with ACHBLF were divided into three subgroups: 33 with early stage ACHBLF (E-ACHBLF), 42 with mid-stage ACHBLF (M-ACHBLF), and 40 with advanced stage ACHBLF (A-ACHBLF). Tβ4 promoter methylation status in peripheral blood mononuclear cells (PBMCs) was measured by methylation-specific polymerase chain reaction, and mRNA was detected by quantitative real-time polymerase chain reaction.

RESULTS

Methylation frequency of Tβ4 was significantly higher in patients with ACHBLF than in those with pre-ACHBLF, CHB or HC. However, expression of Tβ4 mRNA showed the opposite trend. In patients with ACHBLF, Tβ4 promoter methylation status correlated negatively with mRNA levels. The 3-month mortality of ACHBLF in the methylated group was significantly higher than that in the unmethylated group. Also, Tβ4 promoter methylation frequency was lower in survivors than in non-survivors. When used to predict the 1-, 2-, and 3-month incidence of ACHBLF, Tβ4 methylation status was better than the model for end-stage liver disease (MELD) score. The predictive value of Tβ4 methylation was higher than that of MELD score for the mortality of patients with E-ACHBLF and M-ACHBLF, but not for A-ACHBLF.

CONCLUSIONS

Tβ4 methylation might be an important early marker for predicting disease incidence and prognosis in patients with ACHBLF.

Hypomethylation of thymosin β4 promoter is associated with glucocorticoid therapy in patients with acute-on-chronic hepatitis B-induced liver failure

BACKGROUND

We aimed to determine whether the methylation status of thymosin β4 (Tβ4) promoter reflects the severity of acute-on-chronic hepatitis B liver failure (ACHBLF) and whether glucocorticoids affect this status.

METHODS

Fifty-six patients with ACHBLF, 45 with chronic hepatitis B (CHB) and 32 healthy controls (HCs), were retrospectively enrolled. Methylation-specific PCR and real-time PCR were used to detect Tβ4 methylation frequency and mRNA level. The expression of Tβ4 was measured before and after glucocorticoid treatment in patients with ACHBLF. Clinical and laboratory parameters were obtained.

RESULTS

Tβ4 mRNA expression of patients with ACHBLF was lower than in patients with CHB or HCs, but the methylation frequency was higher. Tβ4 promoter methylation frequency was correlated with serum total bilirubin, prothrombin activity and model for end-stage liver disease score. Moreover, Tβ4 promoter methylation frequency decreased and demethylation occurred during glucocorticoid therapy. After glucocorticoid therapy, Tβ4 mRNA expression and liver function were better in patients with low levels of methylation than in those with higher levels. After 90 d, the survival of patients with low levels of methylation was significantly higher than those with high levels.

CONCLUSIONS

Patients with ACHBLF who have low levels of Tβ4 methylation may show a more favorable response to glucocorticoid treatment.

Protection of Icariin Against Hydrogen Peroxide-Induced MC3T3-E1 Cell Oxidative Damage

Objective

The aim of the present study was to evaluate the potential protective mechanism of icariin against oxidative damage caused by hydrogen peroxide in MC3T3‐E1 cells.

Methods

MC3T3‐E1 cells were treated with different concentrations of icariin to explore the optimal dose of icariin. MC3T3‐E1 cells were divided into groups treated with various concentrations of hydrogen peroxide (H₂O₂; 0, 0.1, 0.2, 0.5, 1, and 2 mM) for 24 h to induce oxidative damage and cell viability was assessed by Cell Counting Kit‐8 (CCK‐8) assay. Then, cells were divided into five groups: control, H₂O₂ (0.2 mM), icariin (0.1 μM) and H₂O₂ (0.2 mM), + icariin (0.1 μM). Cell viability was detected by CCK‐8 assay. In addition, the content of glutathione and superoxide dismutase and the activity level of malondialdehyde in these treatment groups were determined. Alkaline phosphatase (ALP) and alizarin red S (ARS) staining were also performed to measure the early and late osteogenesis, respectively. Protein expression of β‐catenin and cyclin D1 was measured by western blot assay. Then, we used an antagonist of Wnt/β‐catenin signaling pathway (DKK‐1) and western blot analysis to further explore potential mechanism.

Results

After 24 h of exposure to 0.2 mM H₂O₂, the viability of MC3T3‐E1 cells was significantly decreased compared to that of the control cells. We first found that icariin can promote cell proliferation of MC3T3‐E1 cells in a dose‐dependent manner, with the dosage 0.1 μM showing the best pro‐proliferative effect. Furthermore, icariin could promote the protein expression of OSX and RUNX2. The results showed that icariin can reverse the inhibitory osteogenic effects of MC3T3‐E1 caused by H₂O₂. In addition, icariin could increase the Wnt‐signaling related proteins. The results showed that MC3T3‐E1 cells in the H₂O₂ (0.2 mM) + icariin (0.1 μM) + Wnt‐signaling antagonist (DKK‐1) group had weaker ALP and ARS staining compared with that observed in the control and H₂O₂ (0.2 mM) + icariin (0.1 μM) groups. The ALP activity and calcium content were decreased in the 0.2 mM H₂O₂ + 0.1 μM icariin + DKK‐1 group compared to that observed in the 0.2 mM H₂O₂ + 0.1 μM icariin group.

Conclusion

The results showed that icariin can increase the viability of MC3T3‐E1 cells, reverse the oxidative stress induced by H₂O₂ and protect MC3T3‐E1 cells against H₂O₂‐induced inhibition of osteogenic differentiation, which may occur through the Wnt/β‐catenin signaling pathway.

Thymosin beta 4 attenuates oxidative stress-induced injury of spinal cord-derived neural stem/progenitor cells through the TLR4/MyD88 pathway

Neural stem/progenitor cells (NSPCs) can enhance regeneration after spinal cord injury (SCI), but survival of transplanted cells remains poor. Understanding how NSPCs respond to the chemical mediators of secondary injury thus is essential for treating SCI. Thymosin β4 (Tβ4) has physiological functions that are highly relevant to SCI. We exposed NSPCs to oxidative stress and found reduced expression of Tβ4 in H₂O₂-injured NSPCs. Using an MTT assay, we found that Tβ4 dose dependently increased viability of the injured NSPCs. Tβ4 also reversed the decreases of intracellular Ca²⁺ concentration and increases of lactate dehydrogenase in NSPCs induced by H₂O₂ treatment. H₂O₂ exposure increased NSPC apoptosis, which Tβ4 decreased. In H₂O₂-induced NSPCs, ROS production and pro-inflammatory cytokines increased, and again, Tβ4 reversed these effects. We investigated the toll-like receptor 4 (TLR4) and myeloid differentiation primary response 88 (MyD88) signaling pathway as an underlying mechanism in Tβ4's protective effect on H₂O₂-exposed NSPCs. Our results showed that Tβ4 reduced expression of TLR4 and MyD88. Moreover, H₂O₂-exposed NSPCs that were treated with the TLR4/MyD88 pathway inhibitor showed a reversal of all the effects caused by H₂O_2, similar to Tβ4's effects. In conclusion, our study determined that Tβ4 attenuated H₂O₂-induced oxidative stress injury in NSPCs via the TLR4/MyD88 pathway.