Alleviating allergic airway diseases by means of short-term administration of IL-2 and dexamethasone

Houttuynia cordata Thunb repairs steroid-induced avascular necrosis of the femoral head through regulating NF-κB signaling pathway

To investigate the influences of Houttuynia cordata Thunb (HCT) in steroid-induced avascular necrosis of the femoral head (SANFH), we conducted a comprehensive study evaluating the effects of HCT on various aspects. Cell Counting Kit-8 assay was used to examine bone marrow stem cells (BMSCs) cell viability. Flow cytometry and lactate dehydrogenase detection assay were conducted to determine cell apoptosis. The levels of apoptosis-related proteins, osteogenic-related markers, inflammatory factors, and nuclear factor kappa B (NF-κB) pathway-associated proteins were determined via western blotting. Hematoxylin and eosin and terminal deoxynucleotidyl transferase dUTP nick-end labeling assays were utilized to verify the effects of HCT in SANFH rats. Our findings revealed that HCT could enhanced cell viability and arrested cell apoptosis in dexamethasone (Dex)-treated BMSCs. Dex increased the levels of cleaved caspase-3, Bcl2-associated X, interleukin (IL)-1β, IL-18, IL-6, p65, and inhibitor of NF-κB kinase β (IKKβ), while this promoting trend was weakened by HCT. Moreover, pyrrolidine dithiocarbamate (PDTC, an inhibitor of NF-κB signaling pathway) further increased the inhibitory role of apoptosis and the levels of IL-1β, IL-18, and IL-6 and the promotional effect of the levels of RUNX2 and ALP in Dex-treated BMSCs. The in-vivo assays showed that HCT decreased the percentage of empty lacunae, apoptosis, and the levels of IL-1β, IL-18, IL-6, p65, and IKKβ in SANFH rats. In conclusion, our study demonstrated that HCT relieved SANFH, which might be possibly achieved by NF-κB pathway.

Epimedin C protects dexamethasone-induced osteoblasts through NRF1/RhoA pathway

Osteoporosis (OP) is a metabolic bone disease that leads to decrease of bone strength and increase bone brittle and fracture. Dexamethasone (DXMS) usage is a common risk factor of OP. In present study, we found that the Epimedin C protect the DXMS-induced OP, Ras Homolog Family Member A transforming protein (RhoA) was increased in osteoblasts (OBs) and OP models. We further revealed that Nrf1 is a transcription factor that responds to Epimedin C and DXMS in modulating RhoA promoter. The results collectively demonstrate that Epimedin C functions as a positive modifier of RhoA via alteration of Nrf1 transcriptional activity on RhoA promoter, thereby, protecting OBs against OP. Our work is the first study identifying the Epimedin C function in balancing the OBs in OP model via Nrf1-RhoA.

Dexamethasone induces osteoblast apoptosis through ROS-PI3K/AKT/GSK3β signaling pathway

BACKGROUND

Osteoblasts play important roles in the process of osteogenesis and prevention of osteonecrosis. Dexamethasone (Dex), a type of glucocorticoids (GCs), induces apoptosis of osteoblasts and leads to the occurrence of non-traumatic osteonecrosis. This study aimed to explore the effects of phosphatidylinositol 3-kinase/Protein kinase 3 (PI3K/AKT) and glycogen synthase kinase 3β (GSK3β) on Dex-induced osteoblasts apoptosis.

METHODS

Viabilities, proliferation, and apoptosis of primary osteoblasts and pre-osteoblast MC3T3-E1 cells after Dex treatment were detected using cell counting kit-8 (CCK-8) assay, 5-bromo-2'-deoxyuridine (BrdU) incorporation assay, FITC-Annexin V/PI staining and western blotting, respectively. 2',7'-Dichlorodihydrofluorescein diacetate (DCFH-DA) staining was performed to measure the intracellular reactive oxygen species (ROS) levels after Dex treatment. N-acetyl-l-cysteine (NAC) was used as ROS scavenger in this research. The expressions of PI3K/AKT and GSK3β in osteoblasts and MC3T3-E1 cells after Dex treatment were analyzed using western blotting and qRT-PCR, respectively. Then the effects of GSK3β knockdown on Dex-induced apoptosis of osteoblasts were explored. Alkaline phosphatase (ALP) activity assay was used to detect the role of Dex in regulating ALP activity.

RESULTS

Dex remarkably inhibited proliferation and induced apoptosis of osteoblasts and MC3T3-E1 cells. Dex potentially attenuated the osteoblast differentiation. The intracellular ROS levels were significantly increased after Dex treatment. Dex suppressed the activation of PI3K/AKT pathway in osteoblasts and MC3T3-E1 cells by down-regulating the expressions of p-PI3K and p-AKT. The expressions of GSK3β in osteoblasts and MC3T3-E1 cells were obviously up-regulated after Dex treatment. Knockdown of GSK3β alleviated Dex-induced osteoblast and MC3T3-E1 cell apoptosis by decreasing the expressions of Bax, cleaved-caspase 3, cleaved-caspase 9 and increasing the expression of Bcl-2.

CONCLUSION

Our research verified that Dex induced osteoblasts apoptosis by ROS-PI3K/AKT/GSK3β signaling pathway.

Short-term intratracheal use of PEG-modified IL-2 and glucocorticoid persistently alleviates asthma in a mouse model

Regulatory T (Treg) cells play an important role in allergic airway diseases, and upregulation of Treg cells is a potential therapeutic strategy for asthma. In this study, we show that short-term intratracheal use of IL-2 combined with glucocorticoid alleviates antigen-induced airway inflammation and reduces airway hyperresponsiveness by expanding antigen-nonspecific Treg cells, with a decrease in T helper 2 (Th2) cells and Th2-associated cytokines. We also designed a long-acting polyethylene glycol (PEG)-modified IL-2 and demonstrated that the optimal dosage form is IL-2(PEG) plus budesonide, which can upregulate Treg cells and ameliorate asthma at a lower dose. The therapeutic effect was faster than treatment with dexamethasone and was effective at a low dose suitable for humans that could last for at least 6 weeks. This study unveils a new therapeutic regimen and suggests that such endogenous Treg therapy could be a useful tool to persistently alleviate asthma.

High-intensity resistance training attenuates dexamethasone-induced muscle atrophy

INTRODUCTION

In this study we investigated the effects of high-intensity resistance training (RT) on dexamethasone (DEX)-induced muscle atrophy in flexor hallucis longus (FHL), tibialis anterior (TA), and soleus (SOL) muscles.

METHODS

Rats underwent either high-intensity RT or were kept sedentary. In the last 10 days they received either DEX (0.5 mg/kg/day, intraperitoneally) or saline.

RESULTS

DEX reduced body weight (-21%), food intake (-28%), FHL and TA muscle mass (-20% and -18%, respectively), and increased muscle-specific ring finger 1 (MuRF-1) protein level (+37% and +45.5%). RT attenuated FHL muscle atrophy through a combination of low increase in MuRF-1 protein level (-3.5%) and significant increases in mammalian target of rapamycin (mTOR) (+63%) and p70S6K (+46% and +49% for control and DEX, respectively) protein levels.

CONCLUSION

RT attenuated DEX-induced muscle atrophy through a combination of increases in mTOR and p70S6K protein levels and a low increase in MuRF-1 protein level.

Differential effects of rapamycin and dexamethasone in mouse models of established allergic asthma

The mammalian target of rapamycin (mTOR) plays an important role in cell growth/differentiation, integrating environmental cues, and regulating immune responses. Our lab previously demonstrated that inhibition of mTOR with rapamycin prevented house dust mite (HDM)-induced allergic asthma in mice. Here, we utilized two treatment protocols to investigate whether rapamycin, compared to the steroid, dexamethasone, could inhibit allergic responses during the later stages of the disease process, namely allergen re-exposure and/or during progression of chronic allergic disease. In protocol 1, BALB/c mice were sensitized to HDM (three i.p. injections) and administered two intranasal HDM exposures. After 6 weeks of rest/recovery, mice were re-exposed to HDM while being treated with rapamycin or dexamethasone. In protocol 2, mice were exposed to HDM for 3 or 6 weeks and treated with rapamycin or dexamethasone during weeks 4-6. Characteristic features of allergic asthma, including IgE, goblet cells, airway hyperreactivity (AHR), inflammatory cells, cytokines/chemokines, and T cell responses were assessed. In protocol 1, both rapamycin and dexamethasone suppressed goblet cells and total CD4(+) T cells including activated, effector, and regulatory T cells in the lung tissue, with no effect on AHR or total inflammatory cell numbers in the bronchoalveolar lavage fluid. Rapamycin also suppressed IgE, although IL-4 and eotaxin 1 levels were augmented. In protocol 2, both drugs suppressed total CD4(+) T cells, including activated, effector, and regulatory T cells and IgE levels. IL-4, eotaxin, and inflammatory cell numbers were increased after rapamycin and no effect on AHR was observed. Dexamethasone suppressed inflammatory cell numbers, especially eosinophils, but had limited effects on AHR. We conclude that while mTOR signaling is critical during the early phases of allergic asthma, its role is much more limited once disease is established.

Multiple in vitro and in vivo regulatory effects of budesonide in CD4+ T lymphocyte subpopulations of allergic asthmatics

BACKGROUND

Increased activation and increased survival of T lymphocytes characterise bronchial asthma.

OBJECTIVES

In this study the effect of budesonide on T cell survival, on inducible co-stimulator T cells (ICOS), on Foxp3 and on IL-10 molecules in T lymphocyte sub-populations was assessed.

METHODS

Cell survival (by annexin V binding) and ICOS in total lymphocytes, in CD4+/CD25+ and in CD4+/CD25- and Foxp3 and IL-10 in CD4+/CD25+ and in CD4+/CD25-cells was evaluated, by cytofluorimetric analysis, in mild intermittent asthmatics (n = 19) and in controls (n = 15). Allergen induced T lymphocyte proliferation and the in vivo effects of budesonide in mild persistent asthmatics (n = 6) were also explored.

RESULTS

Foxp3 was reduced in CD4+/CD25- and in CD4+/CD25+ cells and ICOS was reduced in CD4+/CD25+ cells but it was increased in CD4+CD25-in asthmatics when compared to controls. In asthmatics, in vitro, budesonide was able to: 1) increase annexin V binding and to reduce ICOS in total lymphocytes; 2) increase annexin V binding and Foxp3 and to reduce ICOS in CD4+/CD25- cells; 3) reduce annexin V binding and to increase IL-10 and ICOS in CD4+/CD25+ cells; 4) reduce cell allergen induced proliferation. In vivo, budesonide increased ICOS in CD4+/CD25+ while it increased Foxp3 and IL-10 in CD4+/CD25+ and in CD4+/CD25- cells.

CONCLUSIONS

Budesonide modulates T cell survival, ICOS, Foxp3 and IL-10 molecules differently in T lymphocyte sub-populations. The findings provided shed light on new mechanisms by which corticosteroids, drugs widely used for the clinical management of bronchial asthma, control T lymphocyte activation.