Kewei Ren

Periodic Mechanical Stress Activates PKCδ-Dependent EGFR Mitogenic Signals in Rat Chondrocytes via PI3K-Akt and ERK1/2.

Background/Aims: The present study aimed to analyze the mechanisms by which periodic mechanical stress is translated into biochemical signals, and to verify the important role of signaling molecules including phosphatidylinositol-3-kinase (PI3K)-Akt, protein kinase C (PKC), and epidermal growth factor receptor (EGFR) in chondrocyte proliferation. The effects of periodic mechanical stress on the mitogenesis of chondrocytes have been studied extensively in recent years. However, the mechanisms underlying the ability of chondrocytes to sense and respond to periodic mechanical stress need further investigation. Methods: Two steps were undertaken in the experiment. In the first step, the cells were pretreated with shRNA targeted to Akt or EGFR or PKCδ or control scrambled shRNA. Moreover, they were pretreated with LY294002, GF109203X, Gö6976, rottlerin, and AG1478. They were maintained under static conditions or periodic mechanical stress for 3 days, 8 h per day, prior to direct cell counting and CCK-8 assay, respectively. In the second step, the cells were pretreated with shRNA targeted to Akt or EGFR or PKCδ or control scrambled shRNA. Moreover, they were pretreated with LY294002, AG1478, and rottlerin. They were maintained under static conditions or periodic mechanical stress for 1 h prior to Western blot analysis. Results: Proliferation was inhibited by pretreatment with PKC or PKCδ inhibitor GF109203X or rottlerin and by short hairpin RNA (shRNA) targeted to PKCδ, but not by PKCα inhibitor Gö6976 in chondrocytes in response to periodic mechanical stress. Meantime, rottlerin and shRNA targeted to PKCδ also attenuated EGFR, Akt, and ERK1/2 activation. Furthermore, inhibiting EGFR activity by AG1478 and shRNA targeted to EGFR abrogated chondrocyte proliferation and phosphorylation levels of Akt and extracellular signal-regulated kinase (ERK)1/2 subjected to periodic mechanical stress, while the phosphorylation site of PKCδ was not affected. In addition, pretreatment with the PI3K-Akt-selective inhibitor LY294002 and shRNA targeted to Akt reduced periodic mechanical stress-induced chondrocyte proliferation and phosphorylation of ERK1/2, while the phosphorylation levels of EGFR and PKCδ were not inhibited. Conclusion: These findings suggested that periodic mechanical stress promoted chondrocyte proliferation through PKCδ-EGFR-PI3K-Akt-ERK1/2. They provide a stronger viewpoint for further investigations into chondrocyte mechanobiology under periodic mechanical stress and the ways to improve the quality of tissue-engineered cartilage.

An updated meta-analysis of the signal transducer and activator of transcription 4 (STAT4) rs7574865 G/T polymorphism and rheumatoid arthritis risk in an Asian population.

Objectives: Signal transducer and activator of transcription 4 (STAT4) transmits signals induced by the cytokines interleukin (IL)-12, IL-23, and interferon (IFN)-γ, which play an important role in the development of rheumatoid arthritis (RA). Studies have shown conflicting results concerning the association between the rs7574865 G/T polymorphism in the STAT4 gene and RA in an Asian population. We have performed a meta-analysis to examine this relationship. Method: We searched PubMed and WanFang databases for all papers published up to 5 October 2013. Eight case–control studies with 6029 cases and 4685 controls were retrieved based on the search criteria for RA susceptibility related to the STAT4 rs7574865 G/T polymorphism. Risk ratios (RRs) and 95% confidence intervals (CIs) were used to assess the strength of this association. Publication bias was assessed using Begg’s test. Results: A significant association was found between the STAT4 rs7574865 G/T polymorphism and RA risk (e.g. GG+GT vs. TT: RR 0.96, 95% CI 0.95–0.97; GG+TT vs. GT: RR 0.94, 95% CI 0.91–0.97). Subgroup analysis of rheumatoid factor (RF) status revealed a protective relationship between the STAT4 rs7574865 G/T polymorphism and RF+/RF− RA risk. A similar relationship was detected in the anti-cyclic citrullinated peptide (CCP) status subgroup. No clear evidence of publication bias was detected in the overall analysis. Conclusions: Our study indicates that the STAT4 rs7574865 G/T polymorphism was significantly associated with a decreased RA risk in an Asian population.

Three single nucleotide polymorphisms of TNFAIP3 gene increase the risk of rheumatoid arthritis

Rheumatoid arthritis (RA) is a systemic autoimmune disease characterized by chronic destructive inflammation in synovial joints. To date, many studies explored the associations between tumor necrosis factor alpha inducible protein 3 (TNFAIP3) gene rs6920220, rs2230926, and rs5029937 polymorphisms and the risk of rheumatoid arthritis (RA), but with contradictory results. We therefore conducted a comprehensive meta-analysis to address the associations. We searched in the databases of PubMed and Embase. Pooled odds ratios (ORs) and 95% confidence intervals (CIs) were calculated by the Stata 11.0 software. A total of 21 case-control studies for these three single nucleotide polymorphisms (SNPs) were included in this meta-analysis. Meta-analysis indicated that TNFAIP3 gene rs6920220, rs2230926, and rs5029937 polymorphisms were associated with the increased risk of RA. Stratification analysis of ethnicity found that rs6920220 and rs5029937 polymorphisms increased the risk of RA among Caucasians, while rs2230926 polymorphism increased the risk of RA among Asians. In summary, this meta-analysis confirms that TNFAIP3 gene polymorphisms may play important roles in the pathogenesis of RA.

An updated meta-analysis of the Fc receptor-like 3 –169T/C polymorphism and rheumatoid arthritis risk

Objectives: Published studies have shown conflicting results concerning the association between the –169T/C promoter polymorphism in the Fc receptor-like 3 (FCRL3) gene and rheumatoid arthritis (RA). In this study we conducted an up-to-date meta-analysis to examine the relationship. Method: We searched the PubMed database for all papers published up to 20 April 2012. Overall, 18 case–control studies with 12 620 cases and 12 613 controls were retrieved based on the search criteria for RA susceptibility related to the FCRL3 –169T/C polymorphism. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of this association. Publication bias was assessed using the Egger test. Results: We found that the FCRL3 –169T/C polymorphism increased the risk for RA overall in genetic models (allelic contrast: OR 1.09, 95% CI 1.03–1.14, p = 0.001; homozygote comparison: OR 1.20, 95% CI 1.08–1.34, p = 0.001; dominant genetic model: OR 1.03, 95% CI 1.01–1.05, p = 0.001). Stratified analysis by race also showed a significant positive association with Asians and Caucasians. Subgroup analysis of rheumatoid factor (RF) revealed a slightly positive relationship between the FCRL3 –169T/C polymorphism and RF-positive RA risk. No obvious evidence of publication bias was detected in the overall analysis. Conclusion: Our study indicates that the FCRL3 –169T/C polymorphism is significantly associated with increased RA risk.

Exploration about changes of IL-10, NF-κB and MMP-3 in a rat model of cervical spondylosis

Objectives To investigate the relationship and mechanism between IL‐10, NF‐&kgr;B and MMP‐3 in cervical degenerative disease induced by unbalanced dynamic and static forces in rats. Methods Sixty Sprague Dawley rats were randomized into test (n = 45) and control (n = 15) groups, which were randomly subdivided into three groups corresponding to one‐month, three‐month and six‐month post‐operation. Test group included 10, 15, 20 rats at corresponding postoperative stage and control group had five rats at each time point. By excising cervicodorsal muscles and ligaments of rats to establish unbalanced dynamic and static rat model in test group. The expression of IL‐10, NF‐&kgr;B and MMP‐3 in the intervertebral disc tissue samples of both test and control group rats were detected by immunohistochemistry at one‐month, three‐month and six‐month post‐operation. The results were analyzed and compared among groups. Results Compared with the control group, the positive expression of IL‐10 in test group was significantly higher at three‐month (P < 0.05). In the same model group, IL‐10 was highest at one‐month. Compared with the control group, NF‐kB in test group was higher at one‐month, three‐month and six‐month. In the same model group, NF‐kB was the highest at one‐month, followed by the time at three‐month and six‐month. And, compared with the control group, MMP‐3 was significantly higher in test group at one‐month (P < 0.05). Conclusion Cervical degeneration may accompanied with the changes of IL‐10, NF‐&kgr;B and MMP‐3. HighlightsWe successfully established the rat cervical model with non‐equilibrium of dynamic and static forces, histologic evidence of different degrees of cervical disc degeneration was seen in all test group at each time point postoperation.Cervical degeneration may accompanied with the changes of IL‐10, NF‐&kgr;B and MMP‐3.On the basis of our research, we speculate that some IL‐10 were produced in the process of IVD degeneration, which may activate NF‐&kgr;B signaling pathway.Activated NF‐&kgr;B drives expression of target genes that release of IL‐10 to activate the immune response in turn.IL‐10 suggests a dysregulation of aggrecan aseactivity in human degenerative IVD by damaging the balance between MMPs and TIMPs.

Therapeutic effect of MIPPSO in the thoracolumbar vertebra fracture

The purpose of this study was to compare the efficacy of minimally invasive percutaneous pedicle screw osteosynthesis (MIPPSO) and traditional open pedicle screw osteosynthesis (TOPSO) in the treatment of thoracolumbar vertebra fracture. A retrospective case-control study was conducted in 120 patients with thoracolumbar vertebral fractures treated in the Affiliated Jiangyin Hospital of Southeast University Medical School (Jiangyin, China) from January 2013 to September 2014. They were randomly divided into two groups: MIPPSO and TOPSO groups with 60 cases in each group. The operation time, blood loss, incision length, post-operative bed rest time, hospital stay, visual analogue scale (VAS) pain scores and Oswestry disability index (ODI) scores before and after operation were recorded and analyzed. Inflammatory indexes including serum C-reactive protein (CRP) and creatine kinase (CK), the anterior vertebral height ratio and kyphosis Cobbs angle changes were also observed. The basic data of the two groups were similar, and there was no significant difference in the operation time between the two groups. The perioperative blood loss, length of incision, bed rest time and total hospital stay in the minimally invasive group were less than those in the open group. Levels of post-operative inflammation indicators such as CRP and CK were significantly higher than those of pre-operative (P<0.05), which was more obvious in the TOPSO group (P<0.05). VAS, ODI scores, anterior vertebral height and Cobbs angle were significantly improved at three days, one and 12 months after surgery compared with those before operation. MIPPSO for the treatment of thoracolumbar fractures can achieve similar clinical effects with traditional incision surgery. In addition, it has the advantages of less trauma, less bleeding and shorter post-operative bed rest time and hospital stay.

Periodic Mechanical Stress Induces Extracellular Matrix Expression and Migration of Rat Nucleus Pulposus Cells Through Src-GIT1-ERK1/2 Signaling Pathway

Background/Aims: Periodic mechanical stress has been shown to promote extracellular matrix (ECM) synthesis and cell migration of nucleus pulposus (NP) cells, however, the mechanisms need to be fully elucidated. The present study aimed to investigate the signal transduction pathway in the regulation of NP cells under periodic mechanical stress. Methods: Primary rat NP cells were isolated and seeded on glass slides, and then treated in our self-developed periodic stress field culture system. To further explore the mechanisms, data were analyzed by scratch-healing assay, quantitative reverse transcription polymerase chain reaction (RT-qPCR) analysis, western blotting, and co-immunoprecipitation assay. Results: Under periodic mechanical stress, the mRNA expression of ECM collagen 2A1 (Col2A1) and aggrecan, and migration of NP cells were significantly increased (P < 0.05 for each), associating with increases in the phosphorylation of Src, GIT1, and ERK1/2 (P < 0.05 for each). Pretreatment with the Src inhibitor PP2 reduced periodic mechanical stress-induced ECM synthesis and cell migration of NP cells (P < 0.05 for each), while the phosphorylation of GIT1 and ERK1/2 were inhibited. ECM synthesis, cell migration, and phosphorylation of ERK1/2 were inhibited after pretreatment with the small interfering RNA for GIT1 in NP cells under periodic mechanical stress (P < 0.05 for each), whereas the phosphorylation of Src was not affected. Pretreatment with the ERK1/2 inhibitor PD98059 reduced periodic mechanical stress-induced ECM synthesis and cell migration of NP cells (P < 0.05 for each). Co-immunoprecipitation assay showed that there was a direct interaction between Src and GIT1 and between GIT1 and ERK1/2. Conclusion: In conclusion, periodic mechanical stress induced ECM expression and migration of NP cells via Src-GIT1-ERK1/2 signaling pathway, playing an important role in regulation of NP cells.

Association of ADAM12 gene polymorphisms with knee osteoarthritis susceptibility

Previous studies that evaluated the association between a disintegrin and metalloprotease 12 (ADAM12) gene polymorphisms and knee osteoarthritis (KOA) have given controversial and indefinite results. Therefore, we performed a meta-analysis to confirm this correlation. We searched the PubMed, Embase, and SinoMed databases for all papers published up to April 11, 2017. Overall, five different studies, totaling 2,353 cases and 3,668 controls, were retrieved on the basis of the search criteria for KOA susceptibility related to four polymorphisms (rs3740199, rs1278279, rs1871054, and rs1044122) in the ADAM12 gene. Odds ratios (ORs) and 95% confidence intervals (CIs) were used to assess the strength of this association. Publication bias was assessed using Eggers and Beggs tests. The rs3740199 G/C polymorphism was found to be associated with increased KOA risk in men (e.g., CG versus GG: OR = 1.44, 95% CI = 1.02–2.04, P = 0.040), but not in the overall analysis and in analyses of other subgroups. Significantly increased associations were also found for the rs1871054 polymorphism (e.g., C versus T allele: OR = 1.85, 95% CI = 1.49–2.30, P < 0.001). However, there were no associations for the rs1278279 and rs1044122 polymorphisms. Furthermore, no obvious evidence of publication bias was detected. Our study indicated that the rs1871054 polymorphism of ADAM12 was significantly associated with increased KOA risk.

Interleukin 10 gene rs1800896 polymorphism is associated with the risk of prostate cancer

Numerous studies have uncovered the association of Interleukin-10 (IL-10) gene rs1800896 polymorphism with the risk of prostate cancer (PCa); however, their conclusions were inconsistent. Therefore, we conducted this meta-analysis to evaluate the role of IL-10 rs1800896 polymorphism in the risk of PCa. 16 eligible studies in 15 articles involving 6,301 cases and 6,510 controls were identified by researching PubMed, Google, CNKI, and EMBASE up to April 1, 2017. Our results revealed that IL-10 rs1800896 polymorphism was associated with the decreased risk of PCa under the homozygous model. Subgroup analysis by ethnicity revealed that rs1800896 polymorphism decreased the risk of PCa among Caucasians. In conclusion, IL-10 gene rs1800896 polymorphism is associated with the decreased risk of PCa. Larger studies with more diverse ethnic populations are needed to confirm these results.

Correlation between protein kinase catalytic subunit alpha-1 gene rs13361707 polymorphism and gastric cancer susceptibility in asian populations

A single nucleotide polymorphism (SNP) of the protein kinase catalytic subunit alpha-1 gene (PRKAA1) that confers susceptibility to gastric cancer (GC) was identified by genome-wide association in several case-control studies. However, the results remained controversial and ambiguous. Therefore, we performed a larger meta-analysis to confirm this association. We searched the PubMed, Embase, WanFang, and CNKI databases, without any restriction on language, covering all papers published until Feb 22, 2017. Overall, 14 case-control studies with 14,485 cases and 14,792 controls were retrieved based on the search criteria. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to quantify the strength of the association. Publication bias was assessed by Eggers and Beggs tests. We found that the PRKAA1 rs13361707 C/T polymorphism had no association with GC risk in any of the pooled genetic models (for example, the T-allele vs. C-allele allelic contrast model yielded the following estimates: OR = 0.87, 95% CI = 0.73-1.05, Pheterogeneity = 0.000). Furthermore, in analyses stratified by either source of control or geographical origin of subjects, a statistically significant inverse relationship was detected between PRKAA1 rs13361707 C/T polymorphism and GC risk. No obvious evidence of publication bias was detected in the pooled meta-analysis. Furthermore, we observed that individuals carrying T-allele (TT or TC) genotypes had a lower expression of PRKAA1. Our present study indicated that PRKAA1 rs13361707 C/T was not significantly associated with GC risk, despite few positive results in the subgroups.A single nucleotide polymorphism (SNP) of the protein kinase catalytic subunit alpha-1 gene (PRKAA1) that confers susceptibility to gastric cancer (GC) was identified by genome-wide association in several case-control studies. However, the results remained controversial and ambiguous. Therefore, we performed a larger meta-analysis to confirm this association. We searched the PubMed, Embase, WanFang, and CNKI databases, without any restriction on language, covering all papers published until Feb 22, 2017. Overall, 14 case-control studies with 14,485 cases and 14,792 controls were retrieved based on the search criteria. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to quantify the strength of the association. Publication bias was assessed by Egger’s and Begg’s tests. We found that the PRKAA1 rs13361707 C/T polymorphism had no association with GC risk in any of the pooled genetic models (for example, the T-allele vs. C-allele allelic contrast model yielded the following estimates: OR = 0.87, 95% CI = 0.73–1.05, Pheterogeneity = 0.000). Furthermore, in analyses stratified by either source of control or geographical origin of subjects, a statistically significant inverse relationship was detected between PRKAA1 rs13361707 C/T polymorphism and GC risk. No obvious evidence of publication bias was detected in the pooled meta-analysis. Furthermore, we observed that individuals carrying T-allele (TT or TC) genotypes had a lower expression of PRKAA1. Our present study indicated that PRKAA1 rs13361707 C/T was not significantly associated with GC risk, despite few positive results in the subgroups.