Cleaved SPP1-rich extracellular vesicles from osteoclasts promote bone regeneration via TGFß1/SMAD3 signaling.

Bone remodeling is a tightly coupled process between bone forming osteoblasts (OBs) and bone resorbing osteoclasts (OCs) to maintain bone architecture and systemic mineral homeostasis throughout life. However, the mechanisms responsible for the coupling between OCs and OBs have not been fully elucidated. Herein, we first validate that secreted extracellular vesicles by osteoclasts (OC-EVs) promote osteogenic differentiation of mesenchymal stem cells (MSCs) and further demonstrate the efficacy of osteoclasts and their secreted EVs in treating tibial bone defects. Furthermore, we show that OC-EVs contain several osteogenesis-promoting proteins as cargo. By employing proteomic and functional analysis, we reveal that mature osteoclasts secrete thrombin cleaved phosphoprotein 1 (SPP1) through extracellular vesicles which triggers MSCs osteogenic differentiation into OBs by activating Transforming Growth Factor ß1 (TGFß1) and Smad family member 3 (SMAD3) signaling. In conclusion, our findings prove an important role of SPP1, present as cargo in OC-derived EVs, in signaling to MSCs and driving their differentiation into OBs. This biological mechanism implies a paradigm shift regarding the role of osteoclasts and their signaling toward the treatment of skeletal disorders which require bone formation.

Periodontal disease and emotional disorders: A meta-analysis.

OBJECTIVE: The objective of this study was to evaluate the relationship of periodontal disease with depression and anxiety via a systematic review and meta-analysis. METHOD: We systematically searched the EMBASE, PubMed, Web of Science, PsycINFO, and SinoMed databases (until August 4, 2019) with language restricted to English and Chinese. Case-control, cross-sectional, and cohort studies that calculated the risk ratio (RR), odds ratio (OR)/prevalence OR (POR), and hazard ratio (HR) of depression/anxiety with periodontal disease or the OR/POR/RR/HR of periodontal disease caused by depression/anxiety were included. Observational studies that reported the depression/anxiety scale score of patients with periodontal disease and healthy periodontal subjects aged ≥14 years were also included. We used the standard format to extract the following information from each included study: author/s, survey year, study design, age of participants, periodontal disease definition, depression/anxiety measurement, and summary of results. The Newcastle-Ottawa scale was used to ascertain the quality of the included citations. RESULTS: After screening, 40 studies were included. A meta-analysis of the case-control studies showed that periodontal disease was positively associated with depression (OR = 1.70, 95% confidence interval [CI] â€Š= 1.01-2.83). A meta-analysis of 12 studies showed that periodontal disease was significantly correlated with anxiety (OR = 1.36, 95% CI = 1.11-1.66). A meta-analysis of 18 studies showed that subjects with periodontal disease had higher depression scale score (standardized mean difference [SMD] = 1.05, 95% CI = 0.68-1.41) and anxiety scale score (SMD = 0.70, 95% CI = 0.44-0.96). CONCLUSION: Periodontal disease is associated with emotional disorders. However, the high degree of heterogeneity among studies should be considered. More high-quality prospective studies are required to confirm the relationship.

Porphyromonas gingivalis induces depression via downregulating p75NTR-mediated BDNF maturation in astrocytes.

Many cross-sectional epidemiological studies have shown the incidence of periodontitis is positive correlated with that of depression. However, their causal relationship and underlying mechanism are largely unknown. Porphyromonas gingivalis (Pg) is the main pathogen for periodontitis. Employing female mice treated with Pg every other day for 4 weeks, we found that Pg-mice showed obvious depression-like behavior, an increased number of activated astrocytes and decreased levels of mature brain derived neurotrophic factor (BDNF) and astrocytic p75NTR in the hippocampus. Both hippocampal injection of BDNF and overexpression of p75NTR in astrocytes alleviated Pg-induced depression-like behavior in mice. Moreover, Pg-lipopolysaccharides (LPS) generated similar phenotypes, which were reversed by the TLR-4 inhibitor TAK242. Our results suggest that Pg-LPS decreases the level of astrocytic p75NTR and then downregulates BDNF maturation, leading to depression-like behavior in mice. Our study provides the first evidence that Pg is a modifiable risk factor for depression and uncovers a novel therapeutic target for the treatment of depression.