Icariin ameliorates dexamethasone‑induced bone deterioration in an experimental mouse model via activation of microRNA‑186 inhibition of cathepsin K

Lactobacillus plantarum attenuates glucocorticoid-induced osteoporosis by altering the composition of rat gut microbiota and serum metabolic profile

Introduction

Osteoporosis, one of the most common non-communicable human diseases worldwide, is one of the most prevalent disease of the adult skeleton. Glucocorticoid-induced osteoporosis(GIOP) is the foremost form of secondary osteoporosis, extensively researched due to its prevalence.Probiotics constitute a primary bioactive component within numerous foods, offering promise as a potential biological intervention for preventing and treating osteoporosis. This study aimed to evaluate the beneficial effects of the probiotic Lactobacillus plantarum on bone health and its underlying mechanisms in a rat model of glucocorticoid dexamethasone-induced osteoporosis, using the osteoporosis treatment drug alendronate as a reference.

Methods

We examined the bone microstructure (Micro-CT and HE staining) and analyzed the gut microbiome and serum metabolome in rats.

Results and discussion

The results revealed that L. plantarum treatment significantly restored parameters of bone microstructure, with elevated bone density, increased number and thickness of trabeculae, and decreased Tb.Sp. Gut microbiota sequencing results showed that probiotic treatment increased gut microbial diversity and the ratio of Firmicutes to Bacteroidota decreased. Beneficial bacteria abundance was significantly increased (Lachnospiraceae_NK4A136_group, Ruminococcus, UCG_005, Romboutsia, and Christensenellaceae_R_7_group), and harmful bacteria abundance was significantly decreased (Desulfovibrionaceae). According to the results of serum metabolomics, significant changes in serum metabolites occurred in different groups. These differential metabolites were predominantly enriched within the pathways of Pentose and Glucuronate Interconversions, as well as Propanoate Metabolism. Furthermore, treatment of L. plantarum significantly increased serum levels of Pyrazine and gamma-Glutamylcysteine, which were associated with inhibition of osteoclast formation and promoting osteoblast formation. Lactobacillus plantarum can protect rats from DEX-induced GIOP by mediating the "gut microbial-bone axis" promoting the production of beneficial bacteria and metabolites. Therefore L. plantarum is a potential candidate for the treatment of GIOP.

Alternative Medical Therapy

Background

Complementary/alternative medicine" (CAM) is defined as a diverse range of medical treatments, largely non-allopathic, mostly traditional, and not integrated into the authoritarian healthcare system. Interestingly for some schools, allopathy is alternative/complementary therapy. Osteoporosis is an ever-known disease treated before the era of allopathic medicine. Even though the customary medical system of India is among the most well-known in the world, every continent has its own alternative therapies for various chronic diseases.

Purpose

This review of the scientific information is to help the readers understand how crucial the conceptual underpinnings of alternative medical therapy systems are to the advancement of conventional allopathic practices.

Method

Many older and recent articles about alternative medical therapy in the management of osteoporosis published in scientific journals are reviewed. Relevant information from cross-references on methods of evaluating the efficacy of different modalities and their scientific pathways is included. An effort has been made to summarise the treatment of osteoporosis by these systems. Opinions, impressions, and inferences are added while describing various aspects of these modalities.

Result

The National Library of Medicine has played an active role in publishing studies of the management of osteoporosis by alternative therapies. Many issues of management of osteoporosis still lack reliable treatment. However, good information is now available about choosing alternate medical therapy that has been studied scientifically and has shown promising results.

Conclusion

Medicinal plants and certain natural treatments can treat osteoporosis and its problems. The use of alternate medical therapy has been proven recently by clinical practice and conventional wisdom. This sharing may help the medical practitioner to understand and judiciously allow complementary therapy while treating osteoporosis.

Therapeutic approach of natural products that treat osteoporosis by targeting epigenetic modulation

Osteoporosis (OP) is a metabolic disease that affects bone, resulting in a progressive decrease in bone mass, quality, and micro-architectural degeneration. Natural products have become popular for managing OP in recent years due to their minimal adverse side effects and suitability for prolonged use compared to chemically synthesized products. These natural products are known to modulate multiple OP-related gene expressions, making epigenetics an important tool for optimal therapeutic development. In this study, we investigated the role of epigenetics in OP and reviewed existing research on using natural products for OP management. Our analysis identified around twenty natural products involved in epigenetics-based OP modulation, and we discussed potential mechanisms. These findings highlight the clinical significance of natural products and their potential as novel anti-OP therapeutics.

Spontaneous Osteoclastogenesis, a risk factor for bone metastasis in advanced luminal A-type breast cancer patients

Introduction

Osteolytic bone metastasis in advanced breast cancer stages are a major complication for patient´s quality life and a sign of low survival prognosis. Permissive microenvironments which allow cancer cell secondary homing and later proliferation are fundamental for metastatic processes. The causes and mechanisms behind bone metastasis in breast cancer patients are still an unsolved puzzle. Therefore, in this work we contribute to describe bone marrow pre-metastatic niche in advanced breast cancer patients.

Results

We show an increase in osteoclasts precursors with a concomitant imbalance towards spontaneous osteoclastogenesis which can be evidenced at bone marrow and peripheral levels. Pro-osteoclastogenic factors RANKL and CCL-2 may contribute to bone resorption signature observed in bone marrow. Meanwhile, expression levels of specific microRNAs in primary breast tumors may already indicate a pro-osteoclastogenic scenario prior to bone metastasis.

Discussion

The discovery of prognostic biomarkers and novel therapeutic targets linked to bone metastasis initiation and development are a promising perspective for preventive treatments and metastasis management in advanced breast cancer patients.

Regulation of osteoclast-mediated bone resorption by microRNA

Osteoclast-mediated bone resorption is responsible for bone metabolic diseases, negatively impacting people's health and life. It has been demonstrated that microRNA influences the differentiation of osteoclasts by regulating the signaling pathways during osteoclast-mediated bone resorption. So far, the involved mechanisms have not been fully elucidated. This review introduced the pathways involved in osteoclastogenesis and summarized the related microRNAs binding to their specific targets to mediate the downstream pathways in osteoclast-mediated bone resorption. We also discuss the clinical potential of targeting microRNAs to treat osteoclast-mediated bone resorption as well as the challenges of avoiding potential side effects and producing efficient delivery methods.

Identification of circRNA Expression Profiles in BMSCs from Glucocorticoid-Induced Osteoporosis Model

Background. Circular RNAs (circRNAs) contribute to the regulation of many diseases. However, little is known about the role of circRNAs in the development of glucocorticoid-induced osteoporosis (GIOP). The present study is aimed at systematically characterizing the circRNA expression profiles in GIOP and predict the potential functions of the associated regulatory networks. Methods. A small animal GIOP model was developed in Sprague-Dawley rats given daily intraperitoneal doses of the synthetic glucocorticoid dexamethasone. Micro-CT and bone histomorphometry were performed to characterize the bone loss. Alizarin red S (ARS) staining and alkaline phosphatase (ALP) activity were assessed to determine the osteogenic differentiation potential of BMSCs. RNA sequencing was performed to identify differentially expressed circRNAs in BMSCs between the GIOP and normal groups, which were validated by qRT-PCR. siRNA interference experiments were used to demonstrate their function. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses were performed to predict the functions of differentially expressed circRNAs. The microRNA (miRNA) targets of the circRNAs and circRNA-miRNA interactions were predicted. Results. Micro-CT and bone histomorphometry confirmed the rat GIOP model. Both ARS intensity and ALP activity were decreased in GIOP BMSCs. Seventeen circRNAs were identified by $\text{fold}\text{change}=2.0$ , $p<0.05$ , and $\text{false}\text{discovery}\text{rate}<0.05$ , of which 7 were upregulated and 10 were downregulated. The qRT-PCR results of the selected circRNAs were consistent with the RNA-seq results and showed that circARSB and circAKT3 were significantly upregulated, while circPTEN and circTRPM7 were downregulated in the GIOP group. Further functional experiments found that downregulation of circARSB and circPTEN expression resulted in a corresponding change in osteogenic differentiation, suggesting that circARSB negatively, while circPTEN positively, regulates BMSC osteogenic differentiation. Analysis of circRNA-targeted miRNAs predicted that miR-135a-5p was associated with circARSB and circAKT3, and miR-881-3p was associated with circPTEN and circTRPM7. Furthermore, the signalling pathways associated with these differentially expressed circRNAs were predicted. Conclusions. The present study identified circARSB, circAKT3, circPTEN, and circTRPM7 as being associated with osteogenic differentiation during GIOP through a circRNA-targeted miRNA-mRNA axis, which might provide insight into the pathophysiological mechanism of GIOP.

MicroRNA-186 ameliorates Knee osteoarthritis via regulation of P2X7-mediated Cathepsin-K/Runx2/ADAMTS5 signalling axis in articular chondrocytes

Knee osteoarthritis (KOA) is a chronic joint disorder involving the articular cartilage and tissues around the synovial joint. The key objective of this study was to determine the effect of miR-186-5p administration on the expression of pathogenic signalling in the chondrocytes using a surgical destabilization of the medial meniscus (DMM) model of KOA, and to testify the mechanism of P2X7-mediated regulation of RUNX2/ADAMTS5 axis by miR-186 in the KOA rats. After eight weeks of intra-articular injection of the miR-186-5p and negative control lentivirus samples, the knee cartilage tissues were subjected to histopathological analysis Safranin-O/Fast green staining. Further, the articular chondrocytes were separated and analysed for various proteins including P2X7, cathepsin-K, RUNX2 and ADAMTS5 using Western blotting method. We observed that the protein expressions of P2X7, cathepsin-K/RUNX2/ADAMTS5, and also MMP-13 were upmodulated in the KOA rats, while intra-articular miR-186-5p lentivirus administration prevented these aberrations.

Hence, the study concludes that miR-186 orchestrates P2X7 expression and the P2X7-mediated cathepsin-K/RUNX2/ADAMTS5 axis and regulates the pathogenesis of KOA. In light of this evidence, we propose that molecular therapeutic interventions targeting miR-186 activation might attenuate osteoarthritic cartilage degeneration.

Lycii radicis cortex inhibits glucocorticoid‑induced bone loss by downregulating Runx2 and BMP‑2 expression

Lycii radicis cortex (LRC) has been used to regulate high blood pressure, body temperature, pain and bone disorders in East Asia. Glucocorticoids (GCs), also known as steroids, are potent immunity regulators widely used in the treatment of inflammatory diseases. However, despite their effectiveness, GC usage is strictly controlled due to severe side‑effects, such as osteoporosis. However, further research is required as to date, at least to the best of our knowledge, there is no appropriate model to overcome secondary osteoporosis as a side‑effect of GC use. Thus, the aim of the present study was to establish an experimental model of osteoporosis induced by GC. Furthermore, the present study aimed to establish the research methodology for medical evaluations of the effectiveness and side‑effects of GCs. A secondary osteoporosis animal model was established, and the animals were divided into two groups as follows: The allergic contact dermatitis (ACD)‑induced group and the non‑ACD‑induced group. In the ACD‑induced group, a GC topical application group was compared with a GC subcutaneous injection group. The results revealed that the presence of ACD affected the induction of GC‑mediated osteoporosis. Therefore, the group exhibiting induced ACD that was treated with a topical application of GC was selected for examining the side‑effects of GCs. The effects of LRC on secondary osteoporosis were confirmed in vivo and in vitro. The results indicated that LRC regulated dexamethasone‑induced osteoblast apoptotic markers, including caspase‑6, caspase‑9, X‑linked inhibitor of apoptosis, apoptosis inhibitor 1 and apoptosis inhibitor 2, and increased the expression of osteoblast differentiation‑related genes, such as Runt‑related transcription factor 2 and bone morphogenetic protein 2 in the MC3T3E‑1 cell line. LRC also significantly reduced GC‑induced osteoporosis and exerted anti‑inflammatory effects in vivo. In addition, LRC inhibited the reduction of calbindin‑D28k in the kidney. Overall, the results of the present study suggest that the use of LRC alleviates GC‑induced secondary osteoporosis.

Paeoniflorin Attenuates Dexamethasone-Induced Apoptosis of Osteoblast Cells and Promotes Bone Formation via Regulating AKT/mTOR/Autophagy Signaling Pathway

Paeoniflorin, a natural product derived from Paeonia lactiflora, possesses diverse pharmacological activities such as anti-inflammatory, antitumor, and antidiabetic effects. It has been reported for promoting osteoblastogenesis and inhibiting osteoclastogenesis. This study investigates the therapeutic effects of paeoniflorin in glucocorticoid-induced osteoporosis (GIOP) in vitro and in vivo. MC3T3-E1 cells were incubated with dexamethasone (DEX; 200 μM) and/or paeoniflorin (10 μM), followed by the investigation of cell proliferation, differentiation, mineralization, apoptosis, and autophagy. The AKT activator SC79 was used for evaluating the involvement of the AKT/mTOR signaling pathway. After DEX pretreatments, paeoniflorin promoted osteoblast differentiation and mineralization characterized by increase in Runx2, ALP, beclin-1, and LC3-II/LC3-I ratio levels and a decrease in apoptosis. The autophagy-promoting effects of paeoniflorin were reversed by SC79. C57BL/6 mice were given DEX (1 mg/kg) once daily and paeoniflorin (15 mg/kg) 48 hours for a total of 8 weeks followed by the investigation of histological changes, the trabecular bone microarchitecture, and the levels of bone turnover markers. The results showed that paeoniflorin increased alkaline phosphatase (ALP) activity and upregulated the expression of osteocalcin and beclin-1 but reduced the levels of Bax and C-terminal telopeptide of type I collagen (CTX-1). Thus, paeoniflorin may alleviate DEX-induced osteoporosis by promoting osteogenic differentiation and autophagy via inhibition of the AKT/mTOR signaling pathway.

miRNA Mechanisms Underlying the Association of Beta Blocker Use and Bone Mineral Density

Osteoporosis is a debilitating and costly disease that causes fractures in 33% of women and 20% of men over the age of 50 years. Recent studies have shown that beta blocker (BB) users have higher bone mineral density (BMD) and decreased risk of fracture compared with non-users. The mechanism underlying this association is thought to be due to suppression of adrenergic signaling in osteoblasts, which leads to increased BMD in rodent models; however, the mechanism in humans is unknown. Also, several miRNAs are associated with adrenergic signaling and BMD in separate studies. To investigate potential miRNA mechanisms, we performed a cross-sectional analysis using clinical data, dual-energy X-ray absorptiometry (DXA) scans, and miRNA and mRNA profiling of whole blood from the Framingham Study's Offspring Cohort. We found nine miRNAs associated with BB use and increased BMD. In parallel network analyses, we discovered a subnetwork associated with BMD and BB use containing two of these nine miRNAs, miR-19a-3p and miR-186-5p. To strengthen this finding, we showed that these two miRNAs had significantly higher expression in individuals without incident fracture compared with those with fracture in an external data set. We also noted a similar trend in association between these miRNA and Z-score as calculated from heel ultrasound measures in two external cohorts (SOS-Hip and SHIP-TREND). Because miR-19a directly targets the ADRB1 mRNA transcript, we propose BB use may downregulate ADRB1 expression in osteoblasts through increased miR-19a-3p expression. We used enrichment analysis of miRNA targets to find potential indirect effects through insulin and parathyroid hormone signaling. This analysis provides a starting point for delineating the role of miRNA on the association between BB use and BMD. © 2020 American Society for Bone and Mineral Research (ASBMR).

Noncoding RNAs in subchondral bone osteoclast function and their therapeutic potential for osteoarthritis

Osteoclasts are the only cells that perform bone resorption. Noncoding RNAs (ncRNAs) are crucial epigenetic regulators of osteoclast biological behaviors ranging from osteoclast differentiation to bone resorption. The main ncRNAs, including miRNAs, circRNAs, and lncRNAs, compose an intricate network that influences gene transcription processes related to osteoclast biological activity. Accumulating evidence suggests that abnormal osteoclast activity leads to the disturbance of subchondral bone remodeling, thus initiating osteoarthritis (OA), a prevalent joint disease characterized mainly by cartilage degradation and subchondral bone remodeling imbalance. In this review, we delineate three types of ncRNAs and discuss their related complex molecular signaling pathways associated with osteoclast function during bone resorption. We specifically focused on the involvement of noncoding RNAs in subchondral bone remodeling, which participate in the degradation of the osteochondral unit during OA progression. We also discussed exosomes as ncRNA carriers during the bone remodeling process. A better understanding of the roles of ncRNAs in osteoclast biological behaviors will contribute to the treatment of bone resorption-related skeletal diseases such as OA.

Icariin Attenuates Amyloid-β (Aβ)-Induced Neuronal Insulin Resistance Through PTEN Downregulation

Neuronal insulin resistance is implicated in neurodegenerative diseases. Icariin has been reported to improve insulin resistance in skeletal muscle cells and to restore impaired hypothalamic insulin signaling in the rats with chronic unpredictable mild stress. In addition, icariin can exert the neuroprotective effects in the mouse models of neurodegenerative diseases. However, the molecular mechanisms by which icariin affects neuronal insulin resistance are poorly understood. In the present study, amyloid-β (Aβ) was used to induce insulin resistance in human neuroblastoma SK-N-MC cells. Insulin sensitivity was evaluated by measuring insulin-stimulated Akt T308 phosphorylation and glucose uptake. We found that the phosphatase and tensin homologue deleted on chromosome 10 (PTEN) mediated Aβ-induced insulin resistance. Icariin treatment markedly reduced Aβ-enhanced PTEN protein levels, leading to an improvement in Aβ-induced insulin resistance. Accordingly, PTEN overexpression obviously abolished the protective effects of icariin on Aβ-induced insulin resistance. Furthermore, icariin activated proteasome activity. The proteasome inhibitor MG132 attenuated the effects of icariin on PTEN protein levels. Taken together, these results suggest that icariin protects SK-N-MC cells against Aβ-induced insulin resistance by activating the proteasome-dependent degradation of PTEN. These findings provide an experimental background for the identification of novel molecular targets of icariin, which may help in the development of alternative therapeutic approaches for neurodegenerative diseases.

Icariin Alleviates Glucocorticoid-Induced Osteoporosis through EphB4/Ephrin-B2 Axis

Purpose

Glucocorticoid (GC) is the most important risk factor for osteoporosis (OP); in the present study, we examined the potential mechanism of icariin, a natural bioactive compound isolated from the traditional Chinese herbal Epimedium, for GC-induced OP to explore its potential therapeutic effect.

Methods

We used a GC-induced OP mice model and treated with icariin. Pathological changes were measured by H&E staining, and the effects of icariin on osteoblasts and osteoclasts were measured by immunohistochemistry (IHC) staining and western blot (WB) analyses, while trabecular bone parameters were detected by micro-CT imaging in vivo.

Results

The results showed that in GC-induced OP symptoms, icariin treatment significantly increased the density of the trabecular bone when exposed to GC, revealed by H&E staining and micro-CT imaging. IHC staining showed that GC-induced OP had a lower EphB4 expression and higher Ephrin-B2 expression, but icariin could promote EphB4 while suppressing Ephrin-B2 expression. The WB results also provided evidence of the same protein expression trend, showing that the osteoblast marker OCN and the EphB4 downstream factor RhoA in the GC group were decreased, while both OCN and RhoA expression were significantly increased and the Ephrin-B2 downstream factor Grb4 in in GC group was increased after icariin treatment.

Conclusion

Icariin could improve the characteristics of OP through regulating the balance of the EphB4/Ephrin-B2 pathway. Further preclinical trial is needed to provide certainty of clinical benefits for OP patients.

Inhibition effect of miR-150 on the progression of oral squamous cell carcinoma by data analysis model based on independent sample T-test

To explore the influence of mir-150 (M-150) ornithine decarboxylase (ODC) or inhibition in the development of oral squamous cell carcinoma (OSCC), the malignant tumor (MT) textures removed by surgical resection of maxillofacial tumors in patients with OSCC and the normal neighbor oral textures were collected. Then human OSCC cal-27 cell line was cultivated in vitro. The expression differences of M-150 in MT textures, neighbor textures and cal-27 cells were explored by fluorescence polymerase chain reaction (PCR). Cal-27 cells were transfected with M-150 mimic, M-150 inhibitor (M-150-I) and negative control of different concentrations, respectively, to test the transfection rate. After transfection (AF) with the optimum transfection concentration, the migration rate of transfected cells was explored by cell scratch test. Transwell assay was used to detect the change of aggression rate of transfected cells. Finally, independent sample t-test model was used to explore and compare the results between groups. The results manifested that the expression of M-150 (Eom) in MT textures and cal-27 cells was obviously less than that in neighbor normal textures (P < 0.05). Transfection rate results manifested that M-150 mimic of 100 nmol/L and M-150-I of 50 noml/L had the best efficiency. AF, cell migration and aggression (M&A) rates in the M-150 mimic group were obviously less than those in the negative control group (CP) (P < 0.05), while those in the M-150-I group were obviously upper (P < 0.05), which indicates that the over Eom could inhibit the M&A of OSCC cells, and thus play an effect in inhibiting the development of OSCC.

Therapeutic Anabolic and Anticatabolic Benefits of Natural Chinese Medicines for the Treatment of Osteoporosis

Osteoporosis is a bone disease characterized by increasing osseous fragility and fracture due to the reduced bone mass and microstructural degradation. Primary pharmacological strategies for the treatment of osteoporosis, hormone replacement treatment (HRT), and alendronate therapies may produce adverse side-effects and may not be recommended for long-term usage. Some classic and bone-specific natural Chinese medicine are very popularly used to treat osteoporosis and bone fracture effectively in clinical with their potential value in bone growth and development, but with few adverse side-effects. Current evidence suggests that the treatments appear to improve bone metabolism and attenuate the osteoporotic imbalance between bone formation and bone resorption at a cellular level by promoting osteoblast activity and inhibiting the effects of osteoclasts. The valuable therapies might, therefore, provide an effective and safer alternative to primary pharmacological strategies. Therefore, the purpose of this article is to comprehensively review these classic and bone-specific drugs in natural Chinese medicines for the treatment of osteoporosis that had been deeply and definitely studied and reported with both bone formation and antiresorption effects, including Gynochthodes officinalis (F.C.How) Razafim. & B.Bremer (syn. Morinda officinalis F.C.How), Curculigo orchioides Gaertn., Psoralea corylifolia (L.) Medik Eucommia ulmoides Oliv., Dipsacus inermis Wall. (syn. Dipsacus asperoides C.Y.Cheng & T.M.Ai), Cibotium barometz (L.) J. Sm., Velvet Antler, Cistanche deserticola Ma, Cuscuta chinensis Lam., Cnidium monnieri (L.) Cusson, Epimedium brevicornum Maxim, Pueraria montana (Lour.) Merr. and Salvia miltiorrhiza Bunge., thus providing evidence for the potential use of alternative Chinese medicine therapies to effectively treat osteoporosis.

MicroRNAs: Key Regulators to Understand Osteoclast Differentiation?

MicroRNAs (miRNAs) are small non-coding single-stranded RNAs that represent important posttranscriptional regulators of protein-encoding genes. In particular, miRNAs play key roles in regulating cellular processes such as proliferation, migration, and cell differentiation. Recently, miRNAs emerged as critical regulators of osteoclasts (OCs) biology and have been involved in OCs pathogenic role in several disorders. OCs are multinucleated cells generated from myeloid precursors in the bone marrow, specialized in bone resorption. While there is a growing number of information on the cytokines and signaling pathways that are critical to control the differentiation of osteoclast precursors (OCPs) into mature OCs, the connection between OC differentiation steps and miRNAs is less well-understood. The present review will first summarize our current understanding of the miRNA-regulated pathways in the sequential steps required for OC formation, from the motility and migration of OCPs to the cell-cell fusion and the final formation of the actin ring and ruffled border in the functionally resorbing multinucleated OCs. Then, considering the difficulty of working on primary OCs and on the generation of robust data we will give an update on the most recent advances in the detection technologies for miRNAs quantification and how these are of particular interest for the understanding of OC biology and their use as potential biomarkers.

MicroRNAs are Critical Regulators of Osteoclast Differentiation

PURPOSE OF REVIEW

Our goal is to comprehensively review the most recent reports of microRNA (miRNA) regulation of osteoclastogenesis. We highlight validated miRNA-target interactions and their place in the signaling networks controlling osteoclast differentiation and function.

RECENT FINDINGS

Using unbiased approaches to identify miRNAs of interest and reporter-3'UTR assays to validate interactions, recent studies have elucidated the impact of specific miRNA-mRNA interactions during in vitro osteoclastogenesis. There has been a focus on signaling mediators downstream of the RANK and CSF1R signaling, and genes essential for differentiation and function. For example, several miRNAs directly and indirectly target the master osteoclast transcription factor, Nfatc1 (e.g. miR-124 and miR-214) and Rho-GTPases, Cdc42 and Rac1 (e.g. miR-29 family).

SUMMARY

Validating miRNA expression patterns, targets, and impact in osteoclasts and other skeletal cells is critical for understanding basic bone biology and for fulfilling the therapeutic potential of miRNA-based strategies in the treatment bone diseases.

Corticosteroids and perinatal hypoxic-ischemic brain injury

Perinatal hypoxic-ischemic (HI) brain injury is the major cause of neonatal mortality and severe long-term neurological morbidity. Yet, the effective therapeutic interventions currently available are extremely limited. Corticosteroids act on both mineralocorticoid (MR) and glucocorticoid (GR) receptors and modulate inflammation and apoptosis in the brain. Neuroinflammatory response to acute cerebral HI is a major contributor to the pathophysiology of perinatal brain injury. Here, we give an overview of current knowledge of corticosteroid-mediated modulations of inflammation and apoptosis in the neonatal brain, focusing on key regulatory cells of the innate and adaptive immune response. In addition, we provide new insights into targets of MR and GR in potential therapeutic strategies that could be beneficial for the treatment of infants with HI brain injury.