ERK5 signalling pathway is essential for fluid shear stress-induced COX-2 gene expression in MC3T3-E1 osteoblast.

Bone cells respond to various mechanical stimuli including fluid shear stress (FSS) in vitro. Induction of cyclooxygenase-2 (COX-2) is thought to be important for the anabolic effects of mechanical loading. Recently, extracellular-signal-regulated kinase 5 (ERK5) has been found to be involved in multiple cellular processes. However, the relationship between ERK5 and the induction of COX-2 is still unknown. Here, we investigated the potential involvement of ERK5 in the response of pre-osteoblastic MC3T3-E1 cells upon FSS. MC3T3-E1 cells were subjected to 12 dyn/cm(2) FSS. Then, we established a ERK5 small interfering RNA (siRNA) transfected cell line using the MC3T3-E1 cells. After the successful transfection confirmed by real-time reverse transcription-polymerase chain reaction and Western blotting, the expression of COX-2, cAMP response element-binding protein (CREB), and nuclear factor kappa B cells (NF-κB) were assayed for downstream effectors of activated ERK5 under FSS by Western blotting. Our results showed that FSS could stimulate COX-2 activity, and induce the phosphorylation of ERK5, CREB, and NF-κB. When the MC3T3-E1 cells were transfected using siRNA before exposure to FSS, COX-2 activity was suppressed, and the phosphorylation of CREB and NF-κB was significantly downregulated. In summary, we demonstrated that ERK5 pathway is essential in the induction of COX-2 gene.

The MEK5/ERK5 pathway mediates fluid shear stress promoted osteoblast differentiation.

The aim of this study was to determine the role of the mitogen-activated protein kinase kinase (MEK) 5/extracellular signal-regulated kinase (ERK) 5 pathway in osteoblast differentiation promoted by intermittent fluid shear stress (FSS). MC3T3-E1 osteoblastic cells were subjected to 12 dyn/cm(2) intermittent FSS, and the phenotypic markers for osteoblast differentiation, such as alkaline phosphatase (ALP) activity and expression of osteopontin (OPN) and osteocalcin (OCN), were then examined. The results showed that intermittent FSS could stimulate ERK5 phosphorylation, ALP activity and the expression of OPN and OCN. When the MEK5/ERK5 pathway was selectively inhibited by BIX02189, ALP activity was suppressed, and the expression of OPN and OCN was downregulated. Intermittent FSS induce the expression of Runt-related transcription factor-2 (Runx-2), which is involved in osteoblast differentiation by promoting the transcription of the above genes. Furthermore, the expression of Runx-2 was also reduced after treatment with BIX02189. Finally, we found that intermittent FSS was a more intense stimulus than steady FSS for promoting osteoblast differentiation. In summary, our results suggest that the MEK5/ERK5 pathway mediates osteoblast differentiation promoted by intermittent FSS, which was more effective than steady FSS in the differentiation process. The MEK5/ERK5 pathway also mediates FSS-induced Runx-2 expression in osteoblast differentiation.

[Study on the diagnostic value of different posterior cruciate ligament index measurement methods for anterior cruciate ligament injury].

OBJECTIVE: To compare the posterior cruciate ligament(PCL) index with six different measurement methods, and analyze and verify its clinical diagnostic value in anterior cruciate ligament (ACL) injury. METHODS: The Magnetic resonance imaging (MRI) data of 225 knee joints in our hospital from May 2018 to March 2022 were retrospectively analyzed, aged from 18 to 60 years old, with a median of 32 years old. On the sagittal MRI images of 114 patients with ACL injury and 111 patients with intact ACL, Measure the straight-line distance (A) between the femoral attachment point and the tibial attachment point of the PCL on the MRI sagittal image and the maximum vertical distance (B) between the straight line and the arcuate mark point of the PCL on the sagittal image, calculate the PCL index and evaluate the diagnostic value of the PCL index for ACL injury. RESULTS: The PCL index of the ACL normal group and the ACL injury group were statistically described. There was no significant difference in PCL index 1, 2, 3 and 6 between the two groups(P>0.05). The difference of PCL index 4 and 5 between the two groups was statistically significant (P<0.001). This study only found that the PCL index 2, 6 in the ACL normal group had a negative correlation with the patient's age (correlation coefficient=-0.213, -0.819;P<0.05), and the PCL index 5 in the ACL injury group was significantly correlated with the patient's body mass index(BMI)had a negative correlation (correlation coefficient=-0.277, P<0.05). CONCLUSION: The change of PCL index is helpful for the diagnosis of ACL injury, PCL index 4 and 5 can be used as effective reference indexes for diagnosing ACL injury in clinic.

A meta-analysis of randomized controlled trials of fixation versus nonfixation of mesh in laparoscopic total extraperitoneal inguinal hernia repair.

BACKGROUND: Mesh fixation during laparoscopic total extraperitoneal (TEP) inguinal hernia repair is still controversial. Although many surgeons considered it necessary to fix the mesh, some published studies supported elimination of mesh fixation. Therefore, a meta-analysis based on randomized controlled trials (RCTs) was conducted to compare the effectiveness and safety of fixation versus nonfixation of mesh in TEP. METHODS: RCTs were identified from PubMed, Embase, the Cochrane Library, SCI, and the Chinese Biomedical Literature Database (CBM). Two reviewers assessed the quality of the studies and extracted data independently. The methodological quality was evaluated according to the Cochrane Handbook 5.0.2. Statistical analysis was conducted using the Cochrane software RevMan 5.0.21. RESULTS: Six RCTs involving 772 patients were included. The nonfixation group had advantages in length of hospital stay [MD =-0.37, 95% CI (-0.57, -0.17), p = 0.0003], operative time [MD = -4.19, 95% CI (-7.77, -0.61), p = 0.02], and costs. However, there was no statistically significant difference in hernia recurrence [OR = 2.01, 95% CI (0.37, 11.03), p = 0.42], time to return to normal activities [MD = -0.13, 95% CI (-0.45, 0.19), p = 0.43], seroma [OR = 1.25, 95% CI (0.30, 5.18), p = 0.75], and postoperative pain on postoperative day 1 [MD = -0.21, 95% CI (-0.52, 0.10), p = 0.18] and day 7 [MD = -0.11, 95% CI (-0.42, 0.20), p = 0.47]. CONCLUSIONS: Without increasing the risk of early hernia recurrence, the nonfixation of mesh in TEP appears to be a safe alternative that is associated with less costs, shorter operative time, and hospital stay for the selected patients. Further adequately powered RCTs are required to clarify whether mesh fixation is necessary for the patients with different types of hernias and larger hernia defects.