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Osteoimmunology focuses on the intermodulation between bone and the immune system. Lipopolysaccharide (LPS)-induced bone loss models are commonly used to investigate the interface between inflammation and osteoporosis. Circulating exosomes can regulate physiological and pathological processes through exosomal microRNAs and proteins. In this study, we observed reduced osteoblast number and bone formation in LPS-induced bone loss mice (LPS mice). Levels of circulating exosomes were increased by ~ twofold in LPS mice, and the expression of exosomal miRNAs was significantly changed. miRNAs (miRNA-125b-5p, miRNA-132-3p, and miRNA-214-3p) that were reported to inhibit osteoblast activity were significantly increased in the serum exosomes and bone tissues of LPS mice. Additionally, LPS-induced increases in exosomes significantly inhibited the osteogenic differentiation of MC3T3-E1 cells.

Researchers have linked microgravity in space to the significant imbalance between bone formation and bone resorption that induces persistent bone loss in load-bearing bones. However, the underlying molecular mechanisms are still unclear, which hinders the development of therapeutic measures. The aim of this study was to identify hub genes and explore novel molecular mechanisms underlying microgravity-induced bone loss using transcriptome datasets obtained from the GEO and SRA databases. In summary, comparative RNA expression pattern studies that differ in species (Homo or Mus), models (in vitro or in vivo), microgravity conditions (real microgravity or ground-based simulators) and microgravity duration showed that it is difficult to reach a consistent conclusion about the pathogenesis of microgravity-induced bone loss across these studies. Even so, we identified 11 hub genes and some miRNA-mRNA interactions mainly based on the GSE100930 dataset. Also, the expression of CCL2, ICAM1, IGF1, miR-101-3p and miR-451a markedly changed under clinorotation-microgravity condition. Remarkedly, ICAM1 and miR-451a were key mediators of the osteogenesis of hMSCs under clinorotation-microgravity condition. These findings provide novel insights into the molecular mechanisms of bone loss during microgravity and could indicate potential targets for further countermeasures against this condition.

Microgravity and radiation exposure-induced bone damage is one of the most significant alterations in astronauts after long-term spaceflight. However, the underlying mechanism is still largely unknown. Recent ground-based simulation studies have suggested that this impairment is likely mediated by increased production of reactive oxygen species (ROS) during spaceflight. The small Maf protein MafG is a basic-region leucine zipper-type transcription factor, and it globally contributes to regulation of antioxidant and metabolic networks. Our research investigated the role of MafG in the process of apoptosis induced by simulated microgravity and radiation in MC3T3-E1 cells. We found that simulated microgravity or radiation alone decreased MafG expression and elevated apoptosis in MC3T3-E1 cells, and combined simulated microgravity and radiation treatment aggravated apoptosis. Meanwhile, under normal conditions, increased ROS levels facilitated apoptosis and downregulated the expression of MafG in MC3T3-E1 cells. Overexpression of MafG decreased apoptosis induced by simulated microgravity and radiation. These findings provide new insight into the mechanism of bone damage induced by microgravity and radiation during space flight.

Background Stent-assisted coiling (SAC) has been reported as a feasible and effective treatment of wide-neck cerebral aneurysms. However, the evidence of SAC of ruptured cerebral aneurysm is lacking. There are no prospective multicenter studies regarding SAC of acutely ruptured aneurysms within 72 hours after subarachnoid hemorrhage. The purpose of the study is to evaluate the safety and efficiency of SAC of acutely ruptured cerebral aneurysms. Methods This study is a prospective, multicenter, and observation registry of consecutive patients with acutely ruptured cerebral aneurysms treated with SAC. Acutely ruptured aneurysms were confirmed within 72 h after the onset of the syndrome. This study will enroll at least 300 patients in 7 high-volume tertiary hospitals (more than 150 cerebral aneurysms treated per year). The primary outcomes are treatment-related thromboembolic complications within 30 days of the treatment. The secondary outcomes are any hemorrhagic complications and aneurysm recurrence at 6 months of angiographic follow-up. The clinical outcomes are measured with the Modified Rankin Scale (mRS) at discharge and at the 6 months of follow-up. The favorable outcomes are defined as an mRS of grades 0 and 2. Discussion We will perform a prospective, multicenter, and observational registry study of consecutive patients with wide-neck acutely ruptured cerebral aneurysms to improve the safety strategy of SAC of acutely ruptured cerebral aneurysms. Trial registration Chinese Clinic Trial Registry: ChiCTR2000036972; Registration date: Aug 26, 2020

Mechanical unloading-related bone loss adversely harms astronauts’ health. Nevertheless, the specific molecular basis underlying the phenomenon has not been completely elucidated. Although the bone microvasculature contributes significantly to bone homeostasis, the pathophysiological role of microvascular endothelial cells (MVECs) in bone loss induced by mechanical unloading is not apparent. Here, we discovered that MC3T3-E1 cells could take up exosomes produced by MVECs under clinorotation-unloading conditions (Clino Exos), which then prevented MC3T3-E1 cells from differentiating into mature osteoblasts. Moreover, miR-92b-3p was found to be highly expressed in both unloaded MVECs and derived exosomes. Further experiments demonstrated that miR-92b-3p was transferred into MC3T3-E1 cells by exosomes, resulting in the suppression of osteogenic differentiation, and that encapsulating miR-92b-3p inhibitor into the Clino Exos blocked their inhibitory effects. Furthermore, miR-92b-3p targeted ELK4 and the expression of ELK4 was lessened when cocultured with Clino Exos. The inhibitor-92b-3p-promoted osteoblast differentiation was partially reduced by siRNA-ELK4. Exosomal miR-92b-3p secreted from MVECs under mechanical unloading has been shown for the first time to partially attenuate the function of osteoblasts through downregulation of ELK4, suggesting a potential strategy to protect against the mechanical unloading-induced bone loss and disuse osteoporosis.

Unloading-induced bone loss is a threat to human health and can eventually result in osteoporotic fractures. Although the underlying molecular mechanism of unloading-induced bone loss has been broadly elucidated, the pathophysiological role of long noncoding RNAs (lncRNAs) in this process is unknown. Here, we identified a novel lncRNA, OGRU, a 1816-nucleotide transcript with significantly decreased levels in bone specimens from hindlimb-unloaded mice and in MC3T3-E1 cells under clinorotation-unloading conditions. OGRU overexpression promoted osteoblast activity and matrix mineralization under normal loading conditions, and attenuated the suppression of MC3T3-E1 cell differentiation induced by clinorotation unloading. Furthermore, this study found that supplementation of pcDNA3.1(+)–OGRU via (DSS)6–liposome delivery to the bone-formation surfaces of hindlimb-unloaded (HLU) mice partially alleviated unloading-induced bone loss. Mechanistic investigations demonstrated that OGRU functions as a competing endogenous RNA (ceRNA) to facilitate the protein expression of Hoxa10 by competitively binding miR-320-3p and subsequently promote osteoblast differentiation and bone formation. Taken together, the results of our study provide the first clarification of the role of lncRNA OGRU in unloading-induced bone loss through the miR-320-3p/Hoxa10 axis, suggesting an efficient anabolic strategy for osteoporosis treatment.

We identified a set of ecotype-specific cold-responsive genes, providing candidate genes for enhancing cold resistance in Phoebe bournei (Hemsl.) Yang and other woody plants. Phoebe bournei (Hemsl.) Yang is an indigenous, endangered, precious timber and ornamental tree in China. Cold stress greatly affects the survival of Phoebe species. To elucidate the molecular mechanisms of cold response and identify candidate genes for improving cold resistance, we used RNA-Seq and qRT-PCR to compare the transcriptomic profiles of two ecotypes of P. bournei, cold-resistant Wuyuan (WY) and cold-sensitive Wuping (WP), under cold stress. A total of 3970 and 4433 genes were differentially expressed in WY and WP, respectively, with 2030 differentially expressed genes (DEGs) were specific to WY. Specifically, the categories “defense response”, “secondary metabolites”, and “ABC transporters” were enriched among WY-specific DEGs. Several transcription factor genes might involve in cold stress response, including RAP2-3, NAC2, NAC43, WRKY47, and WRKY51, were induced only in WY, and CBF3, ZAT10, MYB308, and WER exhibited greater cold stress-induced expression changes in WY compared with WP, which may partially explain the distinct transcriptomic changes induced by cold stress between the two ecotypes. Greater fold changes in the expression of starch metabolism-related genes such as BAM1/3 and lower fold changes in the expression of DPE2 were detected in WY, which was consistent with its greater abundance of total soluble sugars. The stronger transcriptional differentiation of related genes under cold stress in WY may explain its greater cold resistance compared with the WP ecotype, providing important genetic resources for improving cold-resistant characteristics in P. bournei. In addition, two interaction networks were constructed, resulting in identification of a series of hub genes, which facilitates functional dissection of the molecular mechanisms involved in the response to cold stress of P. bournei and extends our ability to improve cold resistance in this valued species.

Disuse osteoporosis is common in prolonged therapeutic bed rest, space flight and immobilization due to limb fracture, which is related to reduction of mechanical stress on bone. Mechanical unloading can inhibit the differentiation of osteoblasts, but the detailed mechanism is still unclear. Runt-related transcription factor-2 (Runx2), is an important transcription factor, which plays a crucial role in disuse osteoporosis induced by unloading conditions. In this study, we found that Runx2-targeting mechano-sensitive miR-30 family members, miR-30b, miR-30c, miR-30d and miR-30e increased significantly, and were negatively correlated with the expression of Runx2 under unloading condition. Further studies found that the four miRNAs inhibited the expression of Runx2 and osteoblast differentiation under normal loading, and the knockdown of these miRNAs attenuated partly the inhibition of osteoblast differentiation induced by unloading condition in MC3T3-E1 cells. This study is the first to report miR-30 family members can regulate partly the dysfunction of osteoblasts under unloading condition, which is expected to be targets for the treatment of disuse osteoporosis.