Investigation Into the Effects of Intra-Articular Steroid on Post-Traumatic Osteoarthritis in Distal Radius Fractures: A Randomized Controlled Pilot Study.

PURPOSE: The aim of this prospective, randomized, controlled, double-blinded pilot study was to determine the rates of post-traumatic osteoarthritis and assess joint space width in the presence or absence of a single intra-articular injection of corticosteroid after an acute, intra-articular distal radius fracture (DRF). METHODS: Forty patients received a single, intra-articular, radiocarpal joint injection of 4 mg of dexamethasone (DEX) (n = 19) or normal saline placebo (n = 21) within 2 weeks of a surgically or nonsurgically treated intra-articular DRF. The primary outcome measure was minimum radiocarpal joint space width (mJSW) on noncontrast computed tomography scans at 2 years postinjection. Secondary outcomes were obtained at 3 months, 6 months, 1 year, and 2 years postinjection and included Disabilities of the Arm, Shoulder, and Hand; Michigan Hand Questionnaire; Patient-Rated Wrist Evaluation; wrist range of motion; and grip strength. RESULTS: At 2-year follow-up, there was no difference in mean mJSW between the DEX group (2.2 mm; standard deviation, 0.6; range, 1.4-3.2) and the placebo group (2.3 mm; standard deviation, 0.7; range, 0.9-3.9). Further, there were no differences in any secondary outcome measures at any postinjection follow-up interval. CONCLUSIONS: Radiocarpal joint injection of corticosteroid within 2 weeks of an intra-articular DRF does not appear to affect the development of post-traumatic osteoarthritis within 2 years follow-up in a small pilot cohort. TYPE OF STUDY/LEVEL OF EVIDENCE: Therapeutic II.

Dexamethasone Sensitizes Acute Monocytic Leukemia Cells to Ara-C by Upregulating FKBP51.

In this study, we demonstrated that the expression of FK506 binding protein 51 (FKBP51) is upregulated in acute monocytic leukemia (AML-M5) cells by dexamethasone and aimed to investigate the possible effects of FKBP51 on the growth and cytarabine sensitivity of AML-M5 cells. THP-1 and U937cells were used to establish AML-M5 cell models with FKBP51 overexpression and knockdown, respectively. Cell proliferation, apoptosis and response to cytarabine were investigated by cell cycle, CCK-8 and Flow cytometry analyses. The mice experiment was conducted to detect the role of FKBP51 on AML-M5 cells proliferation and antileukemia effect of Ara-C/Dexamethasone co-therapy in vivo. Western blots were employed to determine protein expression levels. FKBP51 upregulation significantly attenuated THP-1 cell proliferation and sensitized the cells to cytarabine treatment which was further enhanced by dexamethasone. These effects were indicated by decreases in cell viability, S-G2/M phase cell cycle distribution, cytarabine 50% inhibitory concentration (IC50) values and increases in apoptosis and were supported by decreased phosphorylation levels of AKT, GSK3ß and FOXO1A and decreased levels of BCL-2 and increased levels of P21 and P27. In contrast, FKBP51 knockdown led to excessive U937 cell proliferation and cytarabine resistance, as indicated by increased cell viability and S-G2/M phase cell cycle distribution, decreased apoptosis, increased phosphorylation levels of AKT, GSK3ß and FOXO1A, and increased BCL-2 and decreased P21 and P27 expression. In addition, an AKT inhibitor blocked cell cycle progression and reduced cell viability in all groups of cells. Furthermore, SAFit2, a specific FKBP51 inhibitor, increased U937 cell viability and cytarabine resistance as well as AKT phosphorylation. In conclusion, FKBP51 decelerates proliferation and improves the cytarabine sensitivity of AML-M5 cells by inhibiting AKT pathways, and dexamethasone in combination with Ara-C improves the chemosensitivity of AML-M5.

Diphlorethohydroxycarmalol Derived from Ishige okamurae Improves Behavioral and Physiological Responses of Muscle Atrophy Induced by Dexamethasone in an In-Vivo Model.

Muscle atrophy refers to the loss of skeletal muscle mass, myofiber size, and related physical functions such as walking speed or grip strength caused by aging or a lack of physical activity due to injury or illness and can also be attributed to excessive exposure to corticosteroids. Ishige okamurae (IO) and its active component, diphlorethohydroxycarmalol (DPHC), have been known to improve glucose homeostasis by controlling the contraction of skeletal muscles. Based on this idea, we hypothesized that the effects of DPHC and IO extract on muscle metabolism are associated with their role in improving muscle physical function. This study assessed the effects of DPHC or IO extract on muscle behavioral responses with their metabolic properties in muscle atrophy induced by glucocorticoids and dexamethasone (DEX) in vivo. In addition to the improvement in muscle behavioral response by DPHC or IO extract, the loss of muscle fiber and the related metabolic properties by DEX exposure in the gastrocnemius and soleus of calf muscle was prevented. These findings suggest that IO extract and its active component DPHC can potentially prevent muscle atrophy caused by exposure to corticosteroids and could be used to treat reverse skeletal atrophy.

Risk factor analysis for taxane-associated acute pain syndrome under the dexamethasone prophylaxis.

PURPOSE: Taxane-associated acute pain syndrome (T-APS) reportedly occurs in approximately 70% of patients undergoing therapy. We have previously reported that additional dexamethasone (DEX) administration attenuates T-APS. The aim of this study was to reveal risk factor(s) associated with the incidence of T-APS under prophylactic DEX administration. METHODS: In total, 143 patients with breast cancer who received docetaxel (75 mg/m2) or paclitaxel (175 mg/m2)-containing treatment regimens were enrolled. DEX (4-8 mg) was orally administered on days 2-4. Risk factors for the incidence of ≥ G2 and all-grade T-APS, as well as T-APS incidence between taxane-containing regimens in the first cycle, were retrospectively evaluated. RESULTS: Approximately 90% of the patients received taxanes for adjuvant or neoadjuvant chemotherapy. Overall, 55% of patients administered 4 mg DEX, whereas 45% received 8 mg DEX. Pegfilgrastim was administered in 27% of patients. Incidence of ≥ G2 and all-grade T-APS was 23.8%, and 69.2%, respectively. Univariate and multivariate analyses revealed that administration of pegfilgrastim is an independent risk factor for the incidence of ≥ G2 and all-grade T-APS; age younger than 55 years is also a risk factor for all-grade T-APS. Moreover, the incidence of ≥ G2 and all-grade T-APS was 45.5% and 81.8% in a paclitaxel regimen, and 22.0% and 68.2% in docetaxel-including regimens, respectively, revealing increased tendency with paclitaxel administration, with no significant differences. CONCLUSION: Pegfilgrastim co-administration is an independent risk factor for ≥ G2 and all-grade T-APS, and age younger than 55 years is a risk factor of all-grade T-APS under prophylactic DEX administration.

Dexamethasone reduces autoantibody levels in MRL/lpr mice by inhibiting Tfh cell responses.

Previous studies have shown that dexamethasone (Dex) reduces the levels of anti-nuclear (ANA) and anti-dsDNA antibodies in MRL/lpr mice (a mouse model of SLE). However, the effect of Dex on T follicular helper (Tfh) cells is less documented. Here, using the MRL/lpr mouse model, we investigated the influence of Dex on Tfh cells and potential underlying mechanisms. The data showed that the proportion of Tfh cells, identified as CD4+ CXCR5+ ICOS+ , CD4+ CXCR5+ PD-1+ or CD4+ BCL-6+ cells, markedly decreased after treatment with the Dex, in both Balb/c mice and MRL/lpr mice. Dex significantly inhibited IL-21 expression at both the mRNA and the protein levels. Dex also significantly reduced the proportion of germinal centre B cells and decreased serum IgG, IgG2a/b and IgA levels. Moreover, a positive correlation between the proportion of Tfh cells (CD4+ CXCR5+ ICOS+ , CD4+ CXCR5+ PD-1+ or CD4+ BCL-6+ ) and autoantibodies was observed. Dex significantly increased the Prdm1 and Stat5b mRNA expression and decreased the Bcl-6 and c-Maf mRNA expression of CD4+ T cells. In brief, Dex inhibited the Tfh development, which relies on many other transcription factors in addition to Bcl-6. Our data indicate that Dex can be used as a Tfh cell inhibitor in SLE.

Strontium gluconate potently promotes osteoblast development and restores bone formation in glucocorticoid-induced osteoporosis rats.

Glucocorticoid-induced osteoporosis (GIOP) has emerged as a challenge after long-term glucocorticoid administration during the clinical therapy of diverse diseases. Although some candidates for GIOP treatment have been explored, there is still a lack of reliable drugs for GIOP prevention. In this study, rat bone marrow stem cells (rBMSCs) were utilized to investigate the feasibility of applying strontium gluconate (GluSr), which displays mild activity, easy absorption and good biocompatibility, for GIOP prevention. Thirty-two SD rats were divided into 4 groups to explore the effects of GluSr on osteoporosis rescue in vivo. Our results suggested that GluSr markedly alleviated dexamethasone (DEX)-induced apoptosis of osteoblast precursor cells and rBMSCs and enhanced rBMSC osteogenesis differentiation in vitro. GluSr also effectively promoted osteoblast survival, inhibited osteoclast differentiation and restored bone formation in GIOP rat models. Microarray analysis of the femora from GIOP rats treated with GluSr revealed that the signalling pathways of the glucocorticoid receptor (GR), oestrogen receptor gene (ESR) and vitamin D receptor (VDR) were involved in bone restoration by GluSr. In summary, our study proved that GluSr enhanced osteoblast differentiation and suppressed osteoclast activity both in vitro and in vivo. GluSr might function as a novel strontium reagent for GIOP prevention.

Bevacizumab for radiation necrosis following radiotherapy of brain metastatic disease: a systematic review & meta-analysis.

BACKGROUND: Radiotherapy is the mainstay of brain metastasis (BM) management. Radiation necrosis (RN) is a serious complication of radiotherapy. Bevacizumab (BV), an anti-vascular endothelial growth factor monoclonal antibody, has been increasingly used for RN treatment. We systematically reviewed the medical literature for studies reporting the efficacy and safety of bevacizumab for treatment of RN in BM patients. MATERIALS AND METHODS: PubMed, Medline, EMBASE, and Cochrane library were searched with various search keywords such as "bevacizumab" OR "anti-VEGF monoclonal antibody" AND "radiation necrosis" OR "radiation-induced brain necrosis" OR "RN" OR "RBN" AND "Brain metastases" OR "BM" until 1st Aug 2020. Studies reporting the efficacy and safety of BV treatment for BM patients with RN were retrieved. Study selection and data extraction were carried out by independent investigators. Open Meta Analyst software was used as a random effects model for meta-analysis to obtain mean reduction rates. RESULTS: Two prospective, seven retrospective, and three case report studies involving 89 patients with RN treated with BV were included in this systematic review and meta-analysis. In total, 83 (93%) patients had a recorded radiographic response to BV therapy, and six (6.7%) had experienced progressive disease. Seven studies (n = 73) reported mean volume reductions on gadolinium-enhanced T1 (mean: 47.03%, +/- 24.4) and T2-weighted fluid-attenuated inversion recovery (FLAIR) MRI images (mean: 61.9%, +/- 23.3). Pooling together the T1 and T2 MRI reduction rates by random effects model revealed a mean of 48.58 (95% CI: 38.32-58.85) for T1 reduction rate and 62.017 (95% CI: 52.235-71.799) for T2W imaging studies. Eighty-five patients presented with neurological symptoms. After BV treatment, nine (10%) had stable symptoms, 39 (48%) had improved, and 34 (40%) patients had complete resolution of their symptoms. Individual patient data was available for 54 patients. Dexamethasone discontinuation or reduction in dosage was observed in 30 (97%) of 31 patients who had recorded dosage before and after BV treatment. Side effects were mild. CONCLUSIONS: Bevacizumab presents a promising treatment strategy for patients with RN and brain metastatic disease. Radiographic response and clinical improvement was observed without any serious adverse events. Further class I evidence would be required to establish a bevacizumab recommendation in this group of patients.

Increased Hydrostatic Pressure Promotes Primary M1 Reaction and Secondary M2 Polarization in Macrophages.

Patients with chronic anterior uveitis are at particularly high risk of developing secondary glaucoma when corticosteroids [e.g., dexamethasone (Dex)] are used or when inflammatory activity has regressed. Macrophage migration into the eye increases when secondary glaucoma develops and may play an important role in the development of secondary glaucoma. Our aim was to evaluate in vitro if increased hydrostatic pressure and corticosteroids could induce changes in macrophages phenotype. By using a pressure chamber cell culture system, we assessed the effect of increased hydrostatic pressure (HP), inflammation, and immunosuppression (Dex) on the M1/M2 phenotype of macrophages. Bone marrow-derived macrophages (BMDMs) were stimulated with medium, lipopolysaccharide (LPS, 100 ng/ml), Dex (200 ng/ml), or LPS + Dex and incubated with different HP (0, 20, or 60 mmHg) for 2 or 7 days. The numbers of CD86+/CD206- (M1 phenotype), CD86-/CD206+ (M2 phenotype), CD86+/CD206+ (intermediate phenotype), F4/80+/TNF-α+, and F4/80+/IL-10+ macrophages were determined by flow cytometry. TNF-α and IL-10 levels in cell culture supernatants were quantified by ELISA. TNF-α, IL-10, fibronectin, and collagen IV expression in BMDMs were detected by immunofluorescence microscopy. Higher HP polarizes macrophages primarily to an M1 phenotype (LPS, 60 vs. 0 mmHg, d2: p = 0.0034) with less extra cellular matrix (ECM) production and secondary to an M2 phenotype (medium, 60 vs. 0 mmHg, d7: p = 0.0089) (medium, 60 vs. 20 mmHg, d7: p = 0.0433) with enhanced ECM production. Dex induces an M2 phenotype (Dex, medium vs. Dex, d2: p < 0.0001; d7: p < 0.0001) with more ECM production. Higher HP further increased M2 polarization of Dex-treated macrophages (Dex, 60 vs. 0 mmHg, d2: p = 0.0417; d7: p = 0.0454). These changes in the M1/M2 phenotype by high HP or Dex treatment may play a role in the pathogenesis of secondary uveitic glaucoma- or glucocorticoid (GC)-induced glaucoma.

Neonatal DEX exposure leads to hyperanxious and depressive-like behaviors as well as a persistent reduction of BDNF expression in developmental stages.

Brain-derived neurotrophic factor (BDNF), which regulates the neuronal survival, differentiation and synaptic plasticity, has been proved to play a critical role in the pathology and treatment of several psychiatric disorders including depression. Dexamethaone (DEX) is indicated for a number of conditions in perinatal medicine, however, the long-term impact of early-life DEX exposure on BDNF expression in hippocampus remains unknown. Here we found that neonatal DEX(ND) exposure leads to insignificant change of BDNF expression levels in the adulthood, albeit increased hyperanxious and depressive-like behaviors. However, the bdnf mRNA and BDNF protein levels were significantly reduced in all the hippocampal subregions during the developmental stages, including the perinatal period and puberty. We conclude that early life DEX exposure leads to a persistent disturbance of BDNF signaling during the developmental stages, which might be associated with the life-long impairment of hippocampal function.

Folic acid rescues corticosteroid-induced vertebral malformations in chick embryos through targeting TGF-ß signaling.

Folic acid (FA) is routinely supplemented in the food of pregnant women or women planning a pregnancy, but whether FA exerts a positive effect on preventing fetal bone malformation remains obscure. In this study, we first exposed chick embryos with different concentrations of FA (1-10,000 pmol/egg) and studied vertebral mineralization and ossification through alcian blue and alizarin red as well as hematoxylin and eosin staining. Morphological measurements of the thoracic vertebral bodies demonstrated that 100 pmol/egg FA exhibited the tendency of shortening the growth plate, extended the ossification center, and increased the amount of Type I collagen. Second, we suggested that FA treatment promotes osteogenesis by demonstrating increased RUNX family transcription factor 2 (Runx2) and Osterix expressions in MC3T3-E1 and ATDC5 cells. Transforming growth factor-ß (TGF-ß) signaling was also upregulated by FA exposure, and addition of smad2/3 small interfering RNA knocks down FA-induced increased p-smad2/3, Runx2, and Osterix expression in vitro during chondrogenesis induction. Third, we employed dexamethasone (Dex), exposed chick embryos as an animal model of skeletal developmental retardation, to explore whether FA could rescue the loss of embryonic bone mass. Micro-computed tomography imaging showed that the addition of FA improved the reduction of bone mass in our model. Histological analysis of the vertebral bodies revealed that FA dramatically improved the delayed turnover of the zones of growth plate caused by Dex exposure. Immunofluorescence on the chick embryonic vertebrae and chondrocytes showed that FA supplementation upregulated the expression of TGF-ß1, p-smad2/3, and improved Runx2 as well as Osterix expression in the Dex + FA group compared with the Dex group. Lastly, we found that supplementation with TGF-ß1 (1 ng/egg) rescued bone mass loss caused by Dex as was also seen in FA exposure. Taken together these results, our data revealed that FA supplementation was able to rescue Dex exposure-induced inhibitive osteogenesis through targeting on the TGF-ß signaling pathway.

Effects of fluvoxamine on nerve growth factor-induced neurite outgrowth inhibition by dexamethasone in PC12 cells.

In the present study, we examined the effects of fluvoxamine on nerve growth factor (NGF)-induced neurite outgrowth inhibition by dexamethasone (DEX) in PC12 cells. Fluvoxamine increased NGF-induced neurite outgrowth. Compared with co-treatment with NGF and fluvoxamine, p-Akt levels were higher than the values without fluvoxamine. The phosphorylated extracellular regulated kinase 1/2 levels were slightly increased by co-treatment with NGF and fluvoxamine. Fluvoxamine concentration-dependently improved NGF-induced neurite outgrowth inhibition by DEX. Fluvoxamine also improved the decrease in the NGF-induced p-Akt level caused by DEX. Interestingly, the sigma-1 receptor antagonist NE-100 blocked the improvement effects of fluvoxamine on NGF-induced neurite outgrowth inhibition by DEX. The selective sigma-1 receptor agonist PRE-084 also improved NGF-induced neurite outgrowth inhibition by DEX, which is blocked by NE-100. These results indicate that the improvement effects of fluvoxamine on NGF-induced neurite outgrowth inhibition by DEX may be attributable to the phosphorylation of Akt and the sigma-1 receptor.

An in Vitro and in Vivo Study of the Effect of Dexamethasone on Immunoinhibitory Function of Induced Pluripotent Stem Cell-Derived Mesenchymal Stem Cells.

Induced pluripotent stem cell-derived mesenchymal stem cells (iPSC-MSCs) represent a promising cell source for patient-specific cell therapy. We previously demonstrated that they display an immunomodulatory effect on allergic airway inflammation. Glucocorticoids are powerful anti-inflammatory compounds and widely used in the therapy of allergic diseases. However, the effect of glucocorticoids on the immunomodulatory function of iPSC-MSCs remains unknown. This study aimed to determine the effect of dexamethasone (Dex) on the immunomodulatory function of iPSC-MSCs in vitro and in vivo. A total of three human iPSC-MSC clones were generated from amniocyte-derived iPSCs. Anti-CD3/CD28-induced peripheral blood mononuclear cell (PBMC) proliferation was used to assess the effect of Dex on the immunoinhibitory function of iPSC-MSCs in vitro. Mouse models of contact hypersensitivity (CHS) and allergic airway inflammation were induced, and the levels of inflammation in mice were analyzed with the treatments of iPSC-MSCs and Dex, alone and combined. The results showed that Dex did not interfere with the immunoinhibitory effect of iPSC-MSCs on PBMC proliferation. In CHS mice, simultaneous treatment with Dex did not affect the effect of iPSC-MSCs on the inflammation, both in regional draining lymph nodes and in inflamed ear tissue. In addition, co-administration of iPSC-MSCs with Dex decreased the local expression of interferon (IFN)-γ and tumor necrosis factor (TNF)-α in the ears of CHS mice. In the mouse model of allergic airway inflammation, iPSC-MSC treatment combined with Dex resulted in a similar extent of reduction in pulmonary inflammation as iPSC-MSCs or Dex treatment alone. In conclusion, Dex does not significantly affect the immunomodulatory function of iPSC-MSCs both in vitro and in vivo. These findings may have implications when iPSC-MSCs and glucocorticoids are co-administered.

Efficacy of the combination neurokinin-1 receptor antagonist, palonosetron, and dexamethasone compared to others for the prophylaxis of chemotherapy-induced nausea and vomiting: a systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: Chemotherapy-induced nausea and vomiting (CINV), a common side effect of chemotherapy, can substantially impair a patient's quality of life, interfere with a patient's compliance with anticancer therapy, and result in the manifestation of adverse events such as electrolyte imbalance, dehydration and malnutrition. The most recent guidelines published by the Multinational Association of Supportive Care in Cancer (MASCC) and European Society of Medical Oncology (ESMO) recommend the combination of dexamethasone (DEX), a 5-hydroxytrypatmine-3 receptor antagonist (5-HT3RA), preferably palonosetron (PALO), and a neurokinin-1 receptor antagonist (NK1RA) for prophylactic treatment of CINV in patients receiving highly emetogenic chemotherapy (HEC). The aim of this review was to examine the efficacy of triple agent, as reported in randomized controlled trials (RCTs), compared to any other prophylactic treatments. METHODS: A literature search was conducted in Ovid MEDLINE(R), Embase Classic & Embase, and the Cochrane Central Register of Controlled Trials. The primary endpoint was the proportion of patients achieving complete response (CR) in the acute, delayed and overall phase. Secondary endpoints included the percentage of patients who achieved complete control (CC), no nausea and no vomiting in the acute, delayed and overall phases. RESULTS: A total of 17 RCTs were included in this review, of which 3,146 patients were randomized to receive NK1RA, PALO and DEX, and 2,987 patients to receive other antiemetic treatments. The combination was not superior to other treatments in five endpoints-CC and CR in the acute phase, nausea and emesis control in the delayed phase, and nausea in the overall phase-but was superior in the other 11 endpoints. When looking only at HEC and moderately emetogenic chemotherapy (MEC) studies, the combination was only superior to others in three endpoints (delayed and overall CC, and overall emesis control) in HEC setting, which is less than the nine identified endpoints (delayed and overall CR, delayed and overall CC, acute and overall nausea control, and acute, delayed and overall phases for emesis control) in the MEC setting. CONCLUSIONS: The combination of NK1RA, PALO and DEX is superior in the majority of assessed endpoints of this meta-analysis. Further studies should investigate the efficacy and safety of the triple regimen compared to regimens lacking NK1RA, to add to the discussions about whether future CINV prophylaxis guidelines should include NK1RA as a first-line treatment in the MEC setting.

MicroRNA351 targeting TRAF6 alleviates dexamethasone-induced myotube atrophy.

BACKGROUND: Glucocorticoids, including dexamethasone (Dex), are corticosteroids secreted by the adrenal gland, which are used as potent anti-inflammatory, anti-shock, and immunosuppressive agents. Dex is commonly used in patients with malignant tumors, such lung cancer. However, administration of high-dose Dex induces severe atrophy of the skeletal muscle, and the underlying mechanisms of this skeletal muscle atrophy remain unclear. Abundant miRNAs of skeletal muscle, such as miR-351, play an important role in the regulation of extenuating the process of muscle atrophy. METHODS: The mRNA and protein expression of TRAF6, MuRF1, MAFbx was determined by real-time PCR and western blot, while the expression of miR-351 was detected by real-time PCR. The myotubes were transfected with miR-351 mimic, negative control, or miR-351 inhibitor. The C2C12 myotubes diameter was measured. RESULTS: MicroRNA351 (miR-351) level was markedly reduced and the mRNA and protein levels of tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6) were increased in Dex-induced C2C12 myotube atrophy. miR-351 directly interacted with the 3'-untranslated region (3'UTR) of TRAF6. Interestingly, miR-351 administration notably inhibited the reduction of the C2C12 myotube diameter induced by Dex treatment and reduced the levels of TRAF6, muscle-RING-finger protein-1 (MuRF1), and muscle atrophy F-box (MAFbx). CONCLUSIONS: miR-351 counteracts Dex-induced C2C12 myotube atrophy by repressing the TRAF6 expression as well as E3 ubiquitin ligase MuRF1 and MAFbx. miR-351 maybe a potential target for development of a new strategy for skeletal muscle atrophy.

Comparison of polycytidylic acid-induced and dexamethasone-induced thymic atrophy and their thymic expression of RIG-Ⅰ like receptors signaling pathway / 中国免疫学杂志

Objective:To provide experimental evidences for choosing murine models in the pathogenesis research of thymic impairment induced by viral infection,we compared the impacts of polycytidylic acid(Poly(I:C)) and dexamethasone(DEX) on the thymic morphology and thymic output function,and explored the implication of RLR signaling pathway.Methods: 24 male C57BL/6 mice were randomly assigned into three groups and treated with Poly(I:C),DEX,or saline respectively.Thereafter,their thymic morphology,pathological changes,thymic index,and thymic pathology were examined.Their contents of T-cell receptor excision circles (TRECs) and proportions of the naive CD4+T cell in the peripheral blood were determined to evaluate their thymic output function.The expression levels of thymic RLR/MAVS/IFN-α/β signaling pathway and IL-1β were also measured.Results: Both Poly (I:C) and DEX treatment caused thymic atrophy in appearance and structural destruction under the microscope inspection,and DEX treatment did much more severe damage,especially to the thymic cortex.TRECs decreased significantly in both groups.The proportions of na?ve/memory CD4+T cell subsets remained stable,though total CD4+T cell decreased in DEX group,while the proportion of na?ve CD4+T cell in Poly (I:C) group increased significantly.The expression of RIG-Ⅰ,MDA5,LGP2,and IFN-α/β were up-regulated in DEX group, while it remained unchanged in Poly (I:C) group.Conclusion:Both Poly (I:C) and DEX induced thymic atrophy and the impaired thymic output function.Nevertheless,the expression of RLR-IFN signaling pathway up-regulated more significantly in DEX group instead of in Poly (I:C) group.These results implied the existence of different pathological manifestations and mechanisms underlying the impaired thymic function in different animal models,as well as impact on na?ve/memory CD4+T cell proportions.Our research provides references for choosing animal models in the basic research and drug development for viral infection induced thymic atrophy based on the RLR signaling pathway.

From the Cover: Usage of Dexamethasone Increases the Risk of Cranial Neural Crest Dysplasia in the Chick Embryo.

Dexamethasone (Dex) is commonly used in the treatment of a variety of benign and malignant conditions. Unfortunately, although it has a variety of teratogenic effects, it remains used in clinical practice for pregnant women mainly due to limited alternatives. However, there is limited knowledge of the mechanisms that lead to the observed teratogenic effects. In this study, the effects of Dex during embryogenesis on neural crest development were evaluated in the early chick embryos. First, we demonstrated that 100 µl 10-6 M Dex treatment leads to craniofacial developmental defects, and also retards embryo growth and plausibly can cause embryo demise. Second, we demonstrated that Dex represses the production of HNK-1, PAX7, and AP-2α labeled cranial neural crest cells, the progenitor cells of the craniofacial skeleton. Third, double immunofluorescent staining of pHIS3/PAX7 and AP-2α/c-Caspase3 revealed that Dex promotes cell apoptosis but does not change cell proliferation rates. Last, fibroblast growth factor signaling molecules were inhibited by Dex treatment. Dex also inhibited neural crest cells production by repressing Msx1 expression in the developing neural tube and by altering expression of epithelial-mesenchymal transition-related adhesion molecules and cell migration genes. Overall, we obtained experimental evidence that Dex treatment during embryogenesis disrupts cranial neural crest development which in turn causes defective cranial bone development.

False responses of Renilla luciferase reporter control to nuclear receptor TR4.

Renilla luciferase reporter is a widely used internal control in dual luciferase reporter assay system, where its transcription is driven by a constitutively active promoter. However, the authenticity of the Renilla luciferase response in some experimental settings has recently been questioned. Testicular receptor 4 (TR4, also known as NR2C2) belongs to the subfamily 2 of nuclear receptors. TR4 binds to a direct repeat regulatory element in the promoter of a variety of target genes and plays a key role in tumorigenesis, lipoprotein regulation, and central nervous system development. In our experimental system using murine pituitary corticotroph tumor AtT20 cells to investigate TR4 actions on POMC transcription, we found that overexpression of TR4 resulted in reduced Renilla luciferase expression whereas knockdown TR4 increased Renilla luciferase expression. The TR4 inhibitory effect was mediated by the TR4 DNA-binding domain and behaved similarly to the GR and its agonist, Dexamethasone. We further demonstrated that the chimeric intron, commonly present in various Renilla plasmid backbones such as pRL-Null, pRL-SV40, and pRL-TK, was responsible for TR4's inhibitory effect. The results suggest that an intron-free Renilla luciferase reporter may provide a satisfactory internal control for TR4 at certain dose range. Our findings advocate caution on the use of Renilla luciferase as an internal control in TR4-directed studies to avoid misleading data interpretation.

SC79 rescues osteoblasts from dexamethasone though activating Akt-Nrf2 signaling.

Dexamethasone (Dex) causes osteoblast cell injuries. In the present research, we tested the potential effect of SC79, a novel and specific Akt activator, against Dex in osteoblasts. In primary murine osteoblasts and osteoblastic MC3T3-E1 cells, pretreatment with SC79 significantly attenuated Dex-induced cell death. Further, Dex-induced mitochondrial permeability transition pore (mPTP) opening, cytochrome C release and apoptosis activation were dramatically alleviated with SC79 pretreatment in above cells. At the molecular level, SC79 activated Akt, which was indispensable for subsequent osteoblast protection against Dex. Akt inhibitors (LY294002, perifosine and MK-2206) blocked SC79-induced Akt activation and abolished its anti-Dex actions in osteoblasts. Further, SC79 activated Akt downstream Nrf2 (NF-E2-related factor 2) signaling and attenuated Dex-induced oxidative stress in osteoblasts. Nrf2 shRNA knockdown or S40T mutation almost reversed SC79-mediated anti-oxidant and cytoprotective activities in osteoblasts. Together, these results suggest that SC79 activates Akt-Nrf2 signaling to protect osteoblasts from Dex.

miR-135b expression downregulates Ppm1e to activate AMPK signaling and protect osteoblastic cells from dexamethasone.

Activation of AMP-activated protein kinase (AMPK) could potently protect osteoblasts/osteoblastic cells from dexamethasone (Dex). We aim to induce AMPK activation via microRNA ("miRNA") downregulation of its phosphatase Ppm1e. We discovered that microRNA-135b ("miR-135b") targets the 3' untranslated regions (UTRs) of Ppm1e. In human osteoblasticOB-6 cells and hFOB1.19 cells, forced-expression of miR-135b downregulated Ppm1e and activated AMPK signaling. miR-135b also protected osteoblastic cells from Dex. shRNA-induced knockdown of Ppm1e similarly activated AMPK and inhibited Dex-induced damages. Intriguingly, in the Ppm1e-silenced osteoblastic cells, miR-135b expression failed to offer further cytoprotection against Dex. Notably, AMPK knockdown (via shRNA) or dominant negative mutation abolished miR-135b-induced AMPK activation and cytoprotection against Dex. Molecularly, miR-135b, via activating AMPK, increased nicotinamide adenine dinucleotide phosphate (NADPH) activity and inhibited Dex-induced oxidative stress. At last, we found that miR-135b level was increased in human necrotic femoral head tissues, which was correlated with Ppm1e downregulation and AMPK activation. There results suggest that miR-135b expression downregulates Ppm1e to activate AMPK signaling, which protects osteoblastic cells from Dex.

Relationship between hypothalamic-pituitary-adrenal axis dysregulation and insulin resistance in elderly patients with depression.

Cortisol dysregulation has been proposed to be involved in depression. Hypothalamic-pituitary-adrenal (HPA) axis dysregulation associated with major depressive disorder (MDD) was previously reported to be higher in the elderly. Furthermore, insulin resistance and the prevalence of type 2 diabetes are known to increase with aging. The aim of the present study was to determine whether a relationship existed between plasma cortisol levels following the dexamethasone/corticotrophin-releasing hormone (DEX/CRH) test and insulin resistance evaluated by the homeostasis model assessment of insulin resistance (HOMA-R) in elderly MDD subjects. Fifteen unmedicated MDD inpatients and 17 age- and sex-matched healthy controls participated in this study. After overnight fasting, blood samples were collected to measure plasma glucose and insulin concentrations, estimate HOMA-R, and perform the DEX/CRH test to evaluate HPA axis function. The value of the area under the time curve of plasma cortisol concentrations (CortAUC) and peak cortisol values (Cortpeak) following the administration of DEX/CRH both correlated with HOMA-R in MDD group. In contrast, neither CortAUC nor Cortpeak correlated with HOMA-R in controls. This is the first study to directly demonstrate the relationship between HPA axis dysregulation assessed with the DEX/CRH test and the index of insulin resistance estimated as HOMA-R in elderly MDD patients.