Targeting P38 Pathway Regulates Bony Formation via MSC Recruitment during Mandibular Distraction Osteogenesis in Rats

Gene expression supports a single origin of horns and antlers in hoofed mammals

Horns, antlers, and other bony cranial appendages of even-toed hoofed mammals (ruminant artiodactyls) challenge traditional morphological homology assessments. Cranial appendages all share a permanent bone portion with family-specific integument coverings, but homology determination depends on whether the integument covering is an essential component or a secondary elaboration of each structure. To enhance morphological homology assessments, we tested whether juvenile cattle horn bud transcriptomes share homologous gene expression patterns with deer antlers relative to pig outgroup tissues, treating the integument covering as a secondary elaboration. We uncovered differentially expressed genes that support horn and antler homology, potentially distinguish them from non-cranial-appendage bone and other tissues, and highlight the importance of phylogenetic outgroups in homology assessments. Furthermore, we found differentially expressed genes that could support a shared cranial neural crest origin for horns and antlers and expression patterns that refine our understanding of the timing of horn and antler differentiation.

Identification of Functional Modules and Key Pathways Associated with Innervation in Graft Bone-CGRP Regulates the Differentiation of Bone Marrow Mesenchymal Stem Cells via p38 MAPK and Wnt6/β-Catenin

Bone resorption occurs after bone grafting, however, contemporaneous reconstruction of the innervation of the bone graft is a potential treatment to maintain the bone mass of the graft. The innervation of bone is an emerging research topic. To understand the potential molecular mechanisms of bone innervation after bone grafting, we collected normal iliac bone tissue as well as bone grafts with or without innervation from nine patients 1 year after surgery and performed RNA sequencing. We identified differentially expressed genes) from these samples and used the gene ontology and Kyoto Encyclopedia of Genes and Genomes databases for functional enrichment and signaling pathway analysis. In parallel, we established protein-protein interaction networks to screen functional modules. Based on bioinformatic results, we validated in vitro the osteogenic differentiation potential of rat bone marrow mesenchymal stem cells (BMMSCs) after calcitonin gene-related peptide (CGRP) stimulation and the expression of p38 MAPK and Wnt6/β-catenin pathways during osteogenesis. Our transcriptome analysis of bone grafts reveals functional modules and signaling pathways of innervation which play a vital role in the structural and functional integration of the bone graft. Simultaneously, we demonstrate that CGRP regulates the differentiation of BMMSCs through p38 MAPK and Wnt6/β-catenin.

Immunomodulatory effects and mechanisms of distraction osteogenesis

Distraction osteogenesis (DO) is widely used for bone tissue engineering technology. Immune regulations play important roles in the process of DO like other bone regeneration mechanisms. Compared with others, the immune regulation processes of DO have their distinct features. In this review, we summarized the immune-related events including changes in and effects of immune cells, immune-related cytokines, and signaling pathways at different periods in the process of DO. We aim to elucidated our understanding and unknowns about the immunomodulatory role of DO. The goal of this is to use the known knowledge to further modify existing methods of DO, and to develop novel DO strategies in our unknown areas through more detailed studies of the work we have done.

H19 Promotes HCC Bone Metastasis Through Reducing Osteoprotegerin Expression in a Protein Phosphatase 1 Catalytic Subunit Alpha/p38 Mitogen-Activated Protein Kinase-Dependent Manner and Sponging microRNA 200b-3p

BACKGROUND AND AIMS

Bone is the second most frequent site of metastasis for HCC, which leads to an extremely poor prognosis. HCC bone metastasis is typically osteolytic, involving the activation of osteoclasts. Long noncoding RNA H19 plays an important role in the pathogenesis of human cancers. Nonetheless, the mechanism underlying the participation of H19 in HCC bone metastasis remains unclear.

APPROACH AND RESULTS

The current study established a mouse HCC bone metastasis model by using serial intracardiac injection and cell isolation to obtain cells with distinct bone metastasis ability. H19 was highly expressed in these cells and in clinical HCC bone metastasis specimens. Both osteoclastogenesis in vitro and HCC bone metastasis in vivo were promoted by H19 overexpression, whereas these processes were suppressed by H19 knockdown. H19 overexpression attenuated p38 phosphorylation and further down-regulated the expression of osteoprotegerin (OPG), also known as osteoclastogenesis inhibitory factor. However, up-regulated OPG expression as well as suppressed osteoclastogenesis caused by H19 knockdown were recovered by p38 interference, indicating that p38 mitogen-activated protein kinase (MAPK)-OPG contributed to H19-promoted HCC bone metastasis. Furthermore, we demonstrated that H19 inhibited the expression of OPG by binding with protein phosphatase 1 catalytic subunit alpha (PPP1CA), which dephosphorylates p38. SB-203580-mediated inactivation of p38MAPK reversed the down-regulation of HCC bone metastasis caused by H19 knockdown in vivo. Additionally, H19 enhanced cell migration and invasion by up-regulating zinc finger E-box binding homeobox 1 through the sequestration of microRNA (miR) 200b-3p.

CONCLUSIONS

H19 plays a critical role in HCC bone metastasis by reducing OPG expression, which is mediated by the PPP1CA-induced inactivation of the p38MAPK pathway; and H19 also functions as a sponge for miR-200b-3p.

Local administration of allogeneic or autologous bone marrow-derived mesenchymal stromal cells enhances bone formation similarly in distraction osteogenesis

BACKGROUND AIMS

Distraction osteogenesis (DO) is a surgical technique to promote bone regeneration that requires a long time for bone healing. Bone marrow-derived mesenchymal stromal cells (MSCs) have been applied to accelerate bone formation in DO. Allogeneic MSCs are attractive, as they could be ready to use in clinics. Whether allogeneic MSCs would have an effect similar to autologous MSCs with regard to promoting bone formation in DO is still unknown. This study compares the effect of autologous MSCs versus allogeneic MSCs on bone formation in a rat DO model.

METHODS

Rat bone marrow-derived MSCs were isolated, characterized and expanded in vitro. Adult rats were subjected to right tibia transverse osteotomy. On the third day of distraction, each rat received one injection of phosphate-buffered saline (PBS), autologous MSCs or allogeneic MSCs at the distraction site. Tibiae were harvested after 28 days of consolidation for micro-computed tomography examination, mechanical test and histological analysis.

RESULTS

Results showed that treatment with both allogeneic and autologous MSCs promoted bone formation, with significantly higher bone mass, mechanical properties and mineral apposition rate as well as expression of angiogenic and bone formation markers at the regeneration sites compared with the PBS-treated group. No statistical difference in bone formation was found between the allogeneic and autologous MSC treatment groups.

CONCLUSIONS

This study indicates that allogeneic and autologous MSCs have a similar effect on promoting bone consolidation in DO. MSCs from an allogeneic source could be used off-the-shelf with DO to achieve early bone healing.

Lipoxin A4-Mediated p38 MAPK Signaling Pathway Protects Mice Against Collagen-Induced Arthritis

The aim of the article was to study the mechanism of Lipoxin A4 (LXA4)-mediated p38 MAPK pathway protecting mice against collagen-induced arthritis (CIA). The impact of LXA4 (0, 5, 10, 15 nM) on synoviocytes proliferation of CIA mice was detected using 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. CIA mice were treated with LXA4, SB203580 (a p38 inhibitor), and/or anisomycin (a p38 agonist), and the arthritis severity score in each mouse was determined. The gene or protein expressions were detected with Western Blotting, ELISA, or qRT-PCR. LXA4 inhibited the synoviocytes proliferation of CIA mice with decreased levels of TNF-α, IL-6, IL-1β, and IFN-γ and reduced p-p38/total p38 expression in synoviocytes in a dose-dependent manner. LXA4 levels were decreased in synovial tissues and plasma of CIA mice, but p-p38/total p38 expression was increased in synovial tissues. LXA4 could downregulate p-p38/total p38 expression in synovial tissues of CIA mice. Both LXA4 and SB203580 reduced arthritis severity score of CIA mice with the reduction of synovial tissue hyperplasia and inflammatory cell infiltration. CIA mice treated with LXA4 and SB203580 had lower levels of TNF-α, IL-6, IL-1β, and IFN-γ, accompanying decreased MDA as well as increased SOD, CAT,and GPx. However, anisomycin could reverse the protect effects of LXA4 on CIA mice regarding the abovementioned inflammatory factors and oxidative stress indexes. LXA4 protected mice against collagen-induced arthritis via inhibiting p38 MAPK signaling pathway, which may be a potential new therapeutic target for rheumatoid arthritis.

The neural system regulates bone homeostasis via mesenchymal stem cells: a translational approach

Large bone reconstruction is a major clinical issue associated with several challenges, and autograft is the main method for reconstructing large defects of maxillofacial bone. However, postoperative osteoporosis of the bone graft, even with sufficient vascularization, remains a primary problem. Therefore, better understanding of the mechanisms and clinical translation of bone homeostasis is required. Neuronal innervation of the bone is an emerging research topic, especially with regards to the role of peripheral nerves in regulating bone homeostasis. Moreover, sensory and autonomic nerves regulate this process via different types of neurotransmitters, but the specific mechanism is still elusive. In this review article, the current understanding of the interaction between the peripheral nerve and the skeleton system is summarized, with a particular focus on bone marrow mesenchymal stem cells (BMMSCs), except for osteoblasts and osteoclasts. The novel application of nerve-based bone regeneration via BMMSCs may provide a new strategy in tissue engineering and clinical treatment of osteoporosis and bone disorders.

Calcitonin gene-related peptide enhances osteogenic differentiation and recruitment of bone marrow mesenchymal stem cells in rats

The present study evaluated the effects of calcitonin gene-related peptide (CGRP) on bone marrow mesenchymal stem cells (BMMSCs) in vitro and in a rat model of mandibular distraction osteogenesis (MDO). Rat BMMSCs were isolated then treated with CGRP or CGRP antagonist (CGRP8-37). The proliferation and migration ability of BMMSCs was determined using 5-bromo-2′-deoxyuridine and Transwell assays, respectively. Osteogenic-related gene expression was analyzed with reverse transcription-quantitative polymerase chain reaction. For the in vivo analysis, thirty MDO rats were randomly assigned to control, CGRP or CGRP8-37 groups. To evaluate the mobilization of BMMSCs, nestin and stromal cell-derived factor 1 (SDF-1) were detected by immunohistochemistry and ELISA. Rats were sacrificed following 14 days and new bone formation was assessed by histological and micro-computed tomography analysis. In the in vitro results, the CGRP group demonstrated significantly higher migration and proliferation, as well as enhanced alkaline phosphatase and runt-related transcription factor 2 expression compared with the control. In the in vivo experiments, bone mineral density of the newly formed bone in the CGRP group was significantly higher than controls. The nestin and SDF-1 expression in the CGRP group was also significantly upregulated. In conclusion, the present study demonstrated that CGRP administration increased new bone formation, possibly via enhancing BMMSC migration and differentiation in MDO rats.

Molecular mechanisms involved in drug-induced liver injury caused by urate-lowering Chinese herbs: A network pharmacology study and biology experiments

As an important part of the comprehensive treatment methods, the urate-lowering Chinese herbs could provide favorable clinical effects on hyperuricemia in its ability to invigorate spleen and remove dampness. Owing to the long-term duration, it brought up the potential adverse reactions (ADRs) and concerns about the drug-induced liver injury from these herbs. To address this problem, the bioinformatics approaches which combined the network pharmacology, computer simulation and molecular biology experiments were undertaken to elucidate the underlying drug-induced liver injury molecular mechanisms of urate-lowering Chinese herbs. Several electronic databases were searched to identify the potential liver injury compounds in published research. Then, the putative target profile of liver injury was predicted, and the interaction network was constructed based on the links between the compounds, corresponding targets and core pathways. Accordingly, the molecular docking simulation was performed to recognize the representative compounds with hepatotoxicity. Finally, the cell experiments were conducted to investigate the biochemical indicators and expression of the crucial protein that were closely associated with liver injury. In conclusion, the current research revealed that the compounds with potential liver injury including diosgenin, baicalin, saikosaponin D, tetrandrine, rutaecarpine and evodiamine from urate-lowering Chinese herbs, could lead to decline the survival rate of L-02 cell, increase the activities of aspartate aminotransferase (AST), alanine aminotransferase (ALT), lactate dehydrogenase (LDH) and alkaline phosphatase (ALP) in cell-culture medium, enhance the expression of p-p38/p38, while the p38 inhibitor could achieve the trend of regulating and controlling liver injury. These research findings bring further support to the growing evidence that the mechanism of the liver injury induced by the compounds from urate-lowering Chinese herbs may be associated with the activation of p38α.