(-)-Epigallocatechin gallate but not chlorogenic acid suppresses EGF-stimulated migration of osteoblasts via attenuation of p38 MAPK activity

Osteogenic mechanism of chlorogenic acid and its application in clinical practice

Natural polyphenols may have a role in counteracting oxidative stress, which is associated with aging and several bone-related diseases. Chlorogenic acid (CGA) is a naturally occurring polyphenolic compound formed by the esterification of caffeic and quininic acids with osteogenic, antioxidant, and anti-inflammatory properties. This review discusses the potential of CGA to enhance osteogenesis by increasing the osteogenic capacity of mesenchymal stem cells (MSCs), osteoblast survival, proliferation, differentiation, and mineralization, as well as its ability to attenuate osteoclastogenesis by enhancing osteoclast apoptosis and impeding osteoclast regeneration. CGA can be involved in bone remodeling by acting directly on pro-osteoclasts/osteoblasts or indirectly on osteoclasts by activating the nuclear factor kB (RANK)/RANK ligand (RANKL)/acting osteoprotegerin (OPG) system. Finally, we provide perspectives for using CGA to treat bone diseases.

Attenuation by HSP90 inhibitors of EGF-elicited migration of osteoblasts: involvement of p44/p42 MAP kinase

BACKGROUND

We have demonstrated that epidermal growth factor (EGF)-induced migration of osteoblast-like MC3T3-E1 cells is mediated through p44/p42 mitogen-activated protein (MAP) kinase, p38 MAP kinase, stress-activated protein kinase/ c-Jun N-terminal kinase (SAPK/JNK), and Akt.The molecular chaperone heat shock protein 90 (HSP90) is abundantly expressed in osteoblasts. However, the role of HSP90 in osteoblast migration remains obscure.

OBJECTIVE

In this study, we investigated the effect of HSP90 inhibitors on the EGF-induced migration of MC3T3-E1 cells and the mechanism.

METHODS

Clonal osteoblast-like MC3T3-E1 cells were treated with the HSP90 inhibitors geldanamycin or onalespib and then stimulated with EGF. Cell migration was evaluated using the transwell cell migration assay and wound-healing assay. The viability of MC3T3-E1 cells was analyzed using the Cell Counting Kit-8. The phosphorylation of p44/p42 MAP kinase, p38 MAP kinase, SAPK/JNK, Akt, and protein kinase-like endoplasmic reticulum kinase (PERK) was evaluated by western blot analysis.

RESULTS

EGF-induced migration was significantly suppressed by geldanamycin and onalespib, evaluated by both transwell cell migration assay and wound-healing assay. Geldanamycin and onalespib did not significantly alter cell viability. Geldanamycin and onalespib markedly reduced the EGF-induced phosphorylation of p44/p42 MAP kinase, but not p38 MAP kinase or Akt. By contrast, geldanamycin and onalespib increased the EGF-induced phosphorylation of SAPK/JNK. PERK phosphorylation was not significantly affected by geldanamycin or onalespib.

CONCLUSION

Our results strongly suggest that HSP90 inhibitors reduce the EGF-induced osteoblast migration through the p44/p42 MAP kinase.

Pre-Emptive Priming of Human Skin Improves Cutaneous Scarring and Is Superior to Immediate and Delayed Topical Anti-Scarring Treatment Post-Wounding: A Double-Blind Randomised Placebo-Controlled Clinical Trial

The concept of pre-emptive priming of skin pre-surgery offers a novel approach in optimizing cutaneous scarring outcome. We previously showed an anti-scarring topical (epigallocatechin-3-gallate (EGCG)) is effective in improving skin scarring when applied post-surgery. The objective was to deliver an active compound at the optimal time in order to maximize its impact and improve cutaneous scarring. Therefore, pre-emptive application of anti-scarring topical pre-surgery compared with post-surgery can potentially be superior on scarring outcome. This double-blinded randomized placebo-controlled trial compares the effects of pre-emptive priming of skin with an anti-scarring topical pre-surgery versus post-surgery. Healthy volunteers (n = 40) were split into 4-groups; each undergoing different modes of application versus placebo: Group-1 = priming (7Days) pre-injury, Group-2 = priming (3D) pre-injury, Group-3 = immediate (0D) day-of-injury, Group-4 = delayed application (14D) post-injury. Excisional skin-biopsies in upper-arms were evaluated weekly with multiple quantitative devices over 8-weeks. Histological, immunohistochemical, mRNA sequencing and QRT-PCR studies were performed on tissue-biopsies. EGCG reduced mast cells at weeks-4 and 8 by gene and protein analyses (p < 0.01). Group 1 was superior to other groups (p < 0.01) in both clinical (blood flow) and laboratory parameters (elastin and immune marker expression). Additionally, there was down-regulation of angiogenic-markers by mRNA-sequencing and of CD31 and VEGF-A at weeks-4 and 8 (p < 0.01) by immunohistochemistry and at week-4 (p < 0.05) by QRT-PCR. EGCG increased antioxidant levels (HO-1) at week-4 (p < 0.01) plus elastin at week-8 (p < 0.01). In conclusion, pre-emptive priming of skin pre-injury has significant beneficial effects on surgically induced skin scarring shown by reducing mast cells, blood flow and angiogenesis plus increasing elastin content. This clinical trial was registered with ISRCTN (ISRCTN70155584).

Pre-Emptive Priming of Human Skin Improves Cutaneous Scarring and Is Superior to Immediate and Delayed Topical Anti-Scarring Treatment Post-Wounding: A Double-Blind Randomised Placebo-Controlled Clinical Trial

The concept of pre-emptive priming of skin pre-surgery offers a novel approach in optimizing cutaneous scarring outcome. We previously showed an anti-scarring topical (epigallocatechin-3-gallate (EGCG)) is effective in improving skin scarring when applied post-surgery. The objective was to deliver an active compound at the optimal time in order to maximize its impact and improve cutaneous scarring. Therefore, pre-emptive application of anti-scarring topical pre-surgery compared with post-surgery can potentially be superior on scarring outcome. This double-blinded randomized placebo-controlled trial compares the effects of pre-emptive priming of skin with an anti-scarring topical pre-surgery versus post-surgery. Healthy volunteers (n = 40) were split into 4-groups; each undergoing different modes of application versus placebo: Group-1 = priming (7Days) pre-injury, Group-2 = priming (3D) pre-injury, Group-3 = immediate (0D) day-of-injury, Group-4 = delayed application (14D) post-injury. Excisional skin-biopsies in upper-arms were evaluated weekly with multiple quantitative devices over 8-weeks. Histological, immunohistochemical, mRNA sequencing and QRT-PCR studies were performed on tissue-biopsies. EGCG reduced mast cells at weeks-4 and 8 by gene and protein analyses (p < 0.01). Group 1 was superior to other groups (p < 0.01) in both clinical (blood flow) and laboratory parameters (elastin and immune marker expression). Additionally, there was down-regulation of angiogenic-markers by mRNA-sequencing and of CD31 and VEGF-A at weeks-4 and 8 (p < 0.01) by immunohistochemistry and at week-4 (p < 0.05) by QRT-PCR. EGCG increased antioxidant levels (HO-1) at week-4 (p < 0.01) plus elastin at week-8 (p < 0.01). In conclusion, pre-emptive priming of skin pre-injury has significant beneficial effects on surgically induced skin scarring shown by reducing mast cells, blood flow and angiogenesis plus increasing elastin content. This clinical trial was registered with ISRCTN (ISRCTN70155584).

Epidermal Growth Factor Protects Against High Glucose-Induced Podocyte Injury Possibly via Modulation of Autophagy and PI3K/AKT/mTOR Signaling Pathway Through DNA Methylation

AIM

Diabetic nephropathy (DN) is a serious health problem worldwide. Epidermal growth factor (EGF) has suggested as a potential biomarker for the progression of chronic kidney disease. In this study, we examined the effects of EGF on the high glucose (HG)-induced podocyte injury and explored the underlying molecular mechanisms.

METHODS

The cell proliferation, toxicity, and cell apoptosis of podocytes were determined by CCK-8 assay, lactate dehydrogenase release assay, and flow cytometry, respectively, and protein levels in the podocytes were determined by Western blot assay. Mechanistically, DNA methylation analysis, bioinformatic analysis, methylation‑specific PCR and quantitative real-time PCR were used to analyze functional pathways in differentially methylated genes and the expression of the key methylated genes in the podocytes after different interventions.

RESULTS

EGF treatment significantly increased the protein expression level of LC3 and decreased the protein level of P62 in HG-stimulated podocytes, which was attenuated by autophagy inhibitor, 3-methyladenine. EGF increased the cell proliferation and the protein expression levels of nephrin and synaptopodin, but reduced cell toxicity and cell apoptosis and protein expression level of cleaved caspase-3, which was partially antagonized by 3-methyladenine. DNA methylation expression profiles revealed the differential hypermethylation sites and hypomethylation sites among podocytes treated with normal glucose, HG and HG+EGF. GO enrichment analysis showed that DNA methylation was significantly enriched in negative regulation of phosphorylation, cell-cell junction and GTPase binding. KEGG pathway analysis showed that these genes were mainly enriched in PI3K-Akt, Hippo and autophagy pathways. Further validation studies revealed that six hub genes (ITGB1, GRB2, FN1, ITGB3, FZD10 and FGFR1) may be associated with the protective effects of EGF on the HG-induced podocyte injury.

CONCLUSION

In summary, our results demonstrated that EGF exerted protective effects on HG-induced podocytes injury via enhancing cell proliferation and inhibiting cell apoptosis. Further mechanistic studies implied that EGF-mediated protective effects in HG-stimulated podocytes may be associated with modulation of autophagy and PI3K/AKT/mTOR signaling pathway.

Plastrum Testudinis Extract Mitigates Thiram Toxicity in Broilers via Regulating PI3K/AKT Signaling

Tibial dyschondroplasia (TD) negatively affects broilers all over the world, in which the accretion of the growth plate (GP) develops into tibial proximal metaphysis. Plastrum testudinis extract (PTE) is renowned as a powerful antioxidant, anti-inflammatory, and bone healing agent. The current study was conducted to evaluate the efficacy of PTE for the treatment of thiram-induced TD chickens. Broilers (day old; n = 300) were raised for 3 days with normal feed. On the 4th day, three groups (n = 100 each) were sorted, namely, the control (normal diet), TD, and PTE groups (normal diet+ thiram 50 mg/kg). On the 7th day, thiram was stopped in the TD and PTE group, and the PTE group received a normal diet and PTE (30 mg/kg/day). Plastrum testudinis extract significantly restored (p < 0.05) the liver antioxidant enzymes, inflammatory cytokines, serum biochemicals, GP width, and tibia weight as compared to the TD group. The PTE administration significantly increased (p < 0.05) growth performance, vascularization, AKT (serine/threonine-protein kinase), and PI3K expressions and the number of hepatocytes and chondrocytes with intact nuclei were enhanced. In conclusion, PTE has the potential to heal TD lesions and act as an antioxidant and anti-inflammatory drug in chickens exposed to thiram via the upregulation of AKT and PI3K expressions.

Effect of Plastrum Testudinis Extracts on the Proliferation and Osteogenic Differentiation of rBMSCs by Regulating p38 MAPK-Related Genes

Extracts from plastrum testudinis (PTE) are active compounds that have been used to treat bone diseases in traditional Chinese medicine for thousands of years. In previous studies, we demonstrated their effects on glucocorticoid-induced osteoporosis both in vivo and in vitro. However, the mechanisms by which PTE regulates the osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells (rBMSCs) in vitro remain poorly understood. In this study, rBMSCs were treated with medium (CON), PTE, osteogenic induction (OI), and a combination of PTE and OI (PTE+OI) over a 21-day period. We found that PTE significantly promoted rBMSCs osteogenic differentiation and mineralisation after 21 days of culturing. Moreover, PTE+OI further enhanced the differentiation and mineralisation process. PTE upregulated STE20, IGF1R, and p38 MAPK mRNA expression and downregulated TRAF6 mRNA expression. The extracts inhibited TRAF6 protein expression and promoted STE20, IGF1R, and phosphorylated p38 MAPK protein expression. Our results imply that PTE promotes the proliferation and osteogenic differentiation of rBMSCs by upregulating p38 MAPK, STE20, and IGF1R and downregulating TRAF6 expression, which may provide experimental evidence of the potential of PTE in the treatment of osteoporosis.