CCL2 is a critical mechano-responsive mediator in crosstalk between osteoblasts and bone mesenchymal stromal cells.

It has been known that moderate mechanical loading, like that caused by exercise, promotes bone formation. However, its underlying mechanisms remain elusive. Here we showed that moderate running dramatically improved trabecular bone in mice tibias with an increase in bone volume fraction and trabecular number and a decrease in trabecular pattern factor. Results of immunohistochemical and histochemical staining revealed that moderate running mainly increased the number of osteoblasts but had no effect on osteoclasts. In addition, we observed a dramatic increase in the number of colony forming unit-fibroblast in endosteal bone marrow and the percentage of CD45- Leptin receptor+ (CD45- LepR+ ) endosteal mesenchymal progenitors. Bioinformatics analysis of the transcriptional data from gene expression omnibus (GEO) database identified chemokine c-c-motif ligands (CCL2) as a critical candidate induced by mechanical loading. Interestingly, we found that CCL2 was up-regulated mainly in osteoblastic cells in the tibia of mice after moderate running. Further, we found that mechanical loading up-regulated the expression of CCL2 by activating ERK1/2 pathway, thereby stimulating migration of endosteal progenitors. Finally, neutralizing CCL2 abolished the recruitment of endosteal progenitors and the increased bone formation in mice after 4 weeks running. These results therefore uncover an unknown connection between osteoblasts and endosteal progenitors recruited in the increased bone formation induced by mechanical loading.

Analysis of Molecular Mechanism of Erxian Decoction in Treating Osteoporosis Based on Formula Optimization Model.

Osteoporosis (OP) is a highly prevalent orthopedic condition in postmenopausal women and the elderly. Currently, OP treatments mainly include bisphosphonates, receptor activator of nuclear factor kappa-B ligand (RANKL) antibody therapy, selective estrogen receptor modulators, teriparatide (PTH1-34), and menopausal hormone therapy. However, increasing evidence has indicated these treatments may exert serious side effects. In recent years, Traditional Chinese Medicine (TCM) has become popular for treating orthopedic disorders. Erxian Decoction (EXD) is widely used for the clinical treatment of OP, but its underlying molecular mechanisms are unclear thanks to its multiple components and multiple target features. In this research, we designed a network pharmacology method, which used a novel node importance calculation model to identify critical response networks (CRNs) and effective proteins. Based on these proteins, a target coverage contribution (TCC) model was designed to infer a core active component group (CACG). This approach decoded the mechanisms underpinning EXD's role in OP therapy. Our data indicated that the drug response network mediated by the CACG effectively retained information of the component-target (C-T) network of pathogenic genes. Functional pathway enrichment analysis showed that EXD exerted therapeutic effects toward OP by targeting PI3K-Akt signaling (hsa04151), calcium signaling (hsa04020), apoptosis (hsa04210), estrogen signaling (hsa04915), and osteoclast differentiation (hsa04380) via JNK, AKT, and ERK. Our method furnishes a feasible methodological strategy for formula optimization and mechanism analysis and also supplies a reference scheme for the secondary development of the TCM formula.

A Novel Strategy for Decoding and Validating the Combination Principles of Huanglian Jiedu Decoction From Multi-Scale Perspective.

Traditional Chinese medicine (TCM) formulas treat complex diseases through combined botanical drugs which follow specific compatibility rules to reduce toxicity and increase efficiency. "Jun, Chen, Zuo and Shi" is one of most used compatibility rules in the combination of botanical drugs. However, due to the deficiency of traditional research methods, the quantified theoretical basis of herbal compatibility including principles of "Jun, Chen, Zuo and Shi" are still unclear. Network pharmacology is a new strategy based on system biology and multi-disciplines, which can systematically and comprehensively observe the intervention of drugs on disease networks, and is especially suitable for the research of TCM in the treatment of complex diseases. In this study, we systematically decoded the "Jun, Chen, Zuo and Shi" rules of Huanglian Jiedu Decoction (HJD) in the treatment of diseases for the first time. This interpretation method considered three levels of data. The data in the first level mainly depicts the characteristics of each component in single botanical drug of HJD, include the physical and chemical properties of component, ADME properties and functional enrichment analysis of component targets. The second level data is the characterization of component-target-protein (C-T-P) network in the whole protein-protein interaction (PPI) network, mainly include the characterization of degree and key communities in C-T-P network. The third level data is the characterization of intervention propagation properties of HJD in the treatment of different complex diseases, mainly include target coverage of pathogenic genes and propagation coefficient of intervention effect between target proteins and pathogenic genes. Finally, our method was validated by metabolic data, which could be used to detect the components absorbed into blood. This research shows the scientific basis of "Jun-Chen-Zuo-Shi" from a multi-dimensional perspective, and provides a good methodological reference for the subsequent interpretation of key components and speculation mechanism of the formula.