Effects of acute and chronic administration of methylprednisolone on oxidative stress in rat lungs

Use of thiols and implications for the use of inhaled corticosteroids in the presence of oxidative stress in COPD

BACKGROUND

Oxidative stress and persistent airway inflammation are thought to be important contributors to the development of chronic obstructive pulmonary disease (COPD). This review summarizes the evidence for targeting oxidative stress and inflammation in patients with COPD with mucolytic/antioxidant thiols and inhaled corticosteroids (ICS), either alone or in combination.

MAIN BODY

Oxidative stress is increased in COPD, particularly during acute exacerbations. It can be triggered by oxidant air pollutants and cigarette smoke and/or by endogenous reactive oxygen species (ROS) released from mitochondria and activated inflammatory, immune and epithelial cells in the airways, together with a reduction in endogenous antioxidants such as glutathione (GSH). Oxidative stress also drives chronic inflammation and disease progression in the airways by activating intracellular signalling pathways and the release of further inflammatory mediators. ICS are anti-inflammatory agents currently recommended for use with long-acting bronchodilators to prevent exacerbations in patients with moderate-to-severe COPD, especially those with eosinophilic airway inflammation. However, corticosteroids can also increase oxidative stress, which may in turn reduce corticosteroid sensitivity in patients by several mechanisms. Thiol-based agents such as erdosteine, N-acetyl L-cysteine (NAC) and S-carboxymethylcysteine (S-CMC) are mucolytic agents that also act as antioxidants. These agents may reduce oxidative stress directly through the free sulfhydryl groups, serving as a source of reducing equivalents and indirectly though intracellular GSH replenishment. Few studies have compared the effects of corticosteroids and thiol agents on oxidative stress, but there is some evidence for greater antioxidant effects when they are administered together. The current Global Initiative for Chronic Obstructive Lung Disease (GOLD) report supports treatment with antioxidants (erdosteine, NAC, S-CMC) in addition to standard-of-care therapy as they have been demonstrated to reduce COPD exacerbations. However, such studies have demonstrated that NAC and S-CMC reduced the exacerbation risk only in patients not treated with ICS, whereas erdosteine reduced COPD exacerbations irrespective of concomitant ICS use suggesting that erdosteine has additional pharmacological actions to ICS.

CONCLUSIONS

Further clinical trials of antioxidant agents with and without ICS are needed to better understand the place of thiol-based drugs in the treatment of patients with COPD.

A Prospective Study on the Association between Oxidative Stress and Duration of Symptoms in Allergic Rhinitis

Oxidative stress has been known to play an important role in inflammatory responses of allergic rhinitis. We investigated the association between degree of oxidative stress and severity of allergic rhinitis. A total 226 allergic rhinitis students were classified by a history of allergic rhinitis into groups according to number and duration of symptoms within the previous year. The total antioxidant status (TAS) and total oxidant status (TOS) levels were compared among groups. Mean TAS level (14.03 ± 9.09 mmol/L) in the group with more than six months of symptoms had a tendency to be higher (p = 0.068) than that of the group with fewer than six months (12.33 ± 8.83 mmol/L). There was no statistically significant difference in mean TAS or TOS level with number of symptoms (nasal congestion, itching, sneezing and watery rhinorrhea). A multivariate logistic regression showed that the adjusted odds ratio of TAS was 1.655 and the adjusted odds ratio of TOS was 0.972 in more than a six-month duration group. The TAS level was significantly associated with a more than six-month symptom duration (p = 0.034). Our results suggest that antioxidant activity increased when allergic rhinitis became chronic and further research will be needed considering the disease severity.

The brief methylprednisolone administration is crucial to mitigate cardiac dysfunction after myocardial infarction

Acute myocardial infarction (AMI) is one of the major causes of heart failure and mortality. Glucocorticoids administration post-infarction has long been proposed, but it has shown conflicting results so far. This controversy may be associated with the glucocorticoid type and the period when it is administered. To elucidate these, the present aims to evaluate if the brief methylprednisolone acetate administration is determinant for heart adaptation after AMI. Male Wistar rats were divided into 3 groups: sham-operated (SHAM); infarcted (AMI); infarcted treated with methylprednisolone acetate (AMI+M). Immediately after surgery, the AMI+M group received a single dose of methylprednisolone acetate (40 mg/kg i.m.). After 56 days, the cardiac function was assessed and lungs, liver and heart were collected to determine rates of hypertrophy and congestion. Heart was used for oxidative stress and metalloproteinase activity analyses. Methylprednisolone acetate attenuated matrix metalloproteinase-2 activity, cardiac dilatation, and prevented the onset of pulmonary congestion, as well as avoided cardiac hypertrophy. Our data indicate that administration of methylprednisolone acetate shortly after AMI may be a therapeutic alternative for attenuation of detrimental ventricular remodeling.

Antioxidant defense in the eyes of immunocompetent and immunosuppressed mice infected with Acanthamoeba spp

Background

Acanthamoeba spp. are ubiquitous pathogens which cause granulomatous amoebic encephalitis and disseminated infection. Moreover, Acanthamoeba spp. infection of the cornea leads to Acanthamoeba keratitis. Our previous study showed that the infection of an eyeball may also take place via the migration of trophozoites through the optic nerve from the brain to the eyes. The aim of the study was to analyze the activity of enzymatic antioxidants and the concentration of non-enzymatic antioxidant in the eyes of immunocompetent and immunocompromised mice with disseminated acanthamoebiasis.

Results

In the immunocompetent mice infected with Acanthamoeba spp. we noted a significant decrease in catalase activity at 8 and 16 days post-infection (dpi). Glutathione reductase activity was significantly lower at 16 dpi compared to the control group and glutathione concentration was statistically higher at 24 dpi than in the control group. In the immunosuppressed mice, a statistically significant increase in glutathione concentration in the eye samples was found at 16 dpi compared to those not infected with Acanthamoeba spp. In the immunosuppressed mice infected with Acanthamoeba spp., glutathione peroxidase activity was statistically lower at 8 dpi, and glutathione concentration was statistically significantly higher at 16 dpi compared to the control group.

Conclusions

The inflammatory response in the eyes of hosts with experimental acanthamoebiasis led to changes in the activity of enzymatic antioxidants and the content of non-enzymatic antioxidant. Therefore, the dysregulation of antioxidants may play a role in the pathomechanism of Acanthamoeba eye infection.

Markers of Oxidant-Antioxidant Equilibrium in Patients with Sudden Sensorineural Hearing Loss Treated with Hyperbaric Oxygen Therapy

The concentration of thiobarbituric acid reactive substances (TBARSs) in plasma and erythrocytes, the activity of selected antioxidant enzymes in erythrocytes: catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx), and the levels of hemoglobin (HGB) and haematocrit (HCT) were determined in 40 patients with sudden sensorineural hearing loss (SSNHL) subjected to 14 treatment sessions in a Haux Starmed 2200 hyperbaric chamber. Hyperbaric oxygen (HBO) therapy involved breathing 100% oxygen at 0.25 MPa. Blood for analysis was collected from the basilic vein at three time points: before the first HBO session, approximately 5 min after the first session, and after the 14th session. The control group included 20 healthy individuals never before treated with HBO therapy. Compared to the pre-HBO values, a 10% increase (P < 0.05) in the TBARS concentration in erythrocytes, a 28% increase in the GPx activity (P < 0.05), and a 7% decrease in the SOD activity (P < 0.05) were observed after 14 HBO sessions. The CAT activity decreased by 6% (P < 0.05) after the first session. The TBARS concentration in plasma was 13% higher (P < 0.01), while that in erythrocytes was 24% lower (P < 0.001) in the SSNHL patients before the first HBO session compared to the control group. The CAT activity in the SSNHL patients before HBO therapy was 26% higher (P < 0.001) than that in the control group. A statistically significant reduction in HGB and HCT after 14 HBO sessions (P < 0.01) compared to the pre-HBO values was demonstrated. SSNHL is accompanied by disturbance in the oxidant-antioxidant equilibrium. Repeated stimulation with hyperbaric oxygen modulates the activity of antioxidant enzymes. It seems that the increased generation of hydrogen peroxide is responsible for the changes in the activity of antioxidant barrier enzymes observed after HBO sessions.

Relationship between antioxidant defense in Acanthamoeba spp. infected lungs and host immunological status

The role of oxidative stress in the pathogenicity of acanthamoebiasis is an important aspect of the intricate and complex host-parasite relationship. The aim of this experimental study was to determine oxidative stress through the assessment of lipid peroxidation product (LPO) levels and antioxidant defense mechanism in Acanthamoeba spp. lung infections in immunocompetent and immunosuppressed hosts. In Acanthamoeba spp. infected immunocompetent mice we noted a significant increase in lung lipid peroxidation products (LPO) at 8 days and 16 days post infection (dpi). There was a significant upregulation in lung LPO in immunocompetent and immunosuppressed mice infected by Acanthamoeba spp. at 16 dpi. The superoxide dismutase activity decreased significantly in lungs in immunosuppressed mice at 8 dpi. The catalase activity was significantly upregulated in lungs in immunocompetent vs. immunosuppressed group and in immunocompetent vs. control mice at 16 dpi. The glutathione reductase activity was significantly lower in immunosuppressed group vs. immunosuppressed control at 24 dpi. We found significant glutathione peroxidase downregulation in immunocompetent and immunosuppressed groups vs. controls at 8 dpi, and in immunosuppressed vs. immunosuppressed control at 16 dpi. The consequence of the inflammatory response in immunocompetent and immunosuppressed hosts in the course of experimental Acanthamoeba spp. infection was the reduction of the antioxidant capacity of the lungs resulting from changes in the activity of antioxidant enzymes. Therefore, the imbalance between oxidant and antioxidant processes may play a major role in pathology associated with Acanthamoeba pneumonia.

Microglia polarization by methylprednizolone acetate accelerates cuprizone induced demyelination

Glucocorticoids (GC) are known as inflammatory drugs, which are used in neuroinflammatory diseases. Unlike the classic picture, recent studies have revealed that some GC drugs exacerbate inflammatory responses in their acute and prolonged administration. Multiple sclerosis (MS) is a demyelinating inflammatory disorder, in which reactive M1 microglia phenotype play a central role. Since methylprednisolone (MP), as a synthetic GC, are commonly used by MS patients, in this study, we evaluated the effect of long-term administration of MP on microglia polarization in cuprizone (CPZ)-induced MS model. The immunostaining results showed that chronic exposure to MP in the CPZ treated mice increased the number of Iba-1 positive microglia, which significantly expressed IP10 as M1 marker than arginase as M2 marker. MP treatment induced significant amplification in the transcript levels of iNOS and TNF-α (M1-related markers) in the corpus callosum of the MS mice, whereas no change detected in the expression of IL-10 (M2-related marker) between the groups. In addition, evaluation of myelin by luxol fast blue staining and transmission electron microscopy revealed that prolonged MP administration increased demyelination in comparison to the CPZ group. In conclusion, our results show that chronic MP therapy in the CPZ-induced demyelination model of MS polarized microglia to M1 pro-inflammatory phenotype.

Porous Se@SiO2 nanocomposites protect the femoral head from methylprednisolone-induced osteonecrosis

Background

Methylprednisolone (MPS) is an important drug used in therapy of many diseases. However, osteonecrosis of the femoral head is a serious damage in the MPS treatment. Thus, it is imperative to develop new drugs to prevent the serious side effect of MPS.

Methods

The potential interferences Se@SiO₂ nanocomposites may have to the therapeutic effect of methylprednisolone (MPS) were evaluated by classical therapeutic effect index of acute respiratory distress syndrome (ARDS), such as wet-to-dry weight ratio, inflammatory factors IL-1β and TNF-α. And oxidative stress species (ROS) index like superoxide dismutase (SOD) and glutathione (GSH) were tested. Then, the protection effects of Se@SiO₂ have in osteonecrosis of the femoral head (ONFH) were evaluated by micro CT, histologic analysis and Western-blot analysis.

Results

In the present study, we found that in the rat model of ARDS, Se@SiO₂ nanocomposites induced SOD and GSH indirectly to reduce ROS damage. The wet-to-dry weight ratio of lung was significantly decreased after MPS treatment compared with the control group, whereas the Se@SiO₂ did not affect the reduced wet-to-dry weight ratio of MPS. Se@SiO₂ also did not impair the effect of MPS on the reduction of inflammatory factors IL-1β and TNF-α, and on the alleviation of structural destruction. Furthermore, micro CT and histologic analysis confirmed that Se@SiO₂ significantly alleviate MPS-induced destruction of femoral head. Moreover, compared with MPS group, Se@SiO₂ could increase collagen II and aggrecan, and reduce the IL-1β level in the cartilage of femoral head. In addition, the biosafety of Se@SiO₂ in vitro and in vivo were supported by cell proliferation assay and histologic analysis of main organs from rat models.

Conclusion

Se@SiO₂ nanocomposites have a protective effect in MPS-induced ONFH without influence on the therapeutic activity of MPS, suggesting the potential as effective drugs to avoid ONFH in MPS therapy.

The Crosstalk between ROS and Autophagy in the Field of Transplantation Medicine

Many factors during the transplantation process influence posttransplant graft function and survival, including donor type and age, graft preservation methods (cold storage, machine perfusion), and ischemia-reperfusion injury. Successively, they will lead to cellular and molecular alterations that determine cell and ultimately organ fate. Oxidative stress and autophagy are implicated in posttransplant outcome since they are both affected by the stress responses triggered in each step (donor, preservation, and recipient) of the transplantation process. Furthermore, oxidative stress influences autophagy and vice versa. Interestingly, both processes have positive as well as negative effects on graft outcome, suggesting they are tightly linked during the transplantation process. In this review, we discuss the importance, regulation and crosstalk of oxidative signals, and autophagy in the field of transplantation medicine.

Treatment of steroid-induced osteonecrosis of the femoral head using porous Se@SiO2 nanocomposites to suppress reactive oxygen species

Reducing oxidative stress (ROS) have been demonstrated effective for steroid-induced osteonecrosis of the femoral head (steroid-induced ONFH). Selenium (Se) plays an important role in suppressing oxidative stress and has huge potential in ONFH treatments. However the Se has a narrow margin between beneficial and toxic effects which make it hard for therapy use in vivo. In order to make the deficiency up, a control release of Se (Se@SiO₂) were realized by nanotechnology modification. Porous Se@SiO₂ nanocomposites have favorable biocompatibility and can reduced the ROS damage effectively. In vitro, the cck-8 analysis, terminal dexynucleotidyl transferase (TdT)-mediated dUTP nick end labeling (TUNEL) stain and flow cytometry analysis showed rare negative influence by porous Se@SiO₂ nanocomposites but significantly protective effect against H₂O₂ by reducing ROS level (detected by DCFH-DA). In vivo, the biosafety of porous Se@SiO₂ nanocomposites were confirmed by the serum biochemistry, the ROS level in serum were significantly reduced and the curative effect were confirmed by Micro CT scan, serum Elisa assay (inflammatory factors), Western blotting (quantitative measurement of ONFH) and HE staining. It is expected that the porous Se@SiO₂ nanocomposites may prevent steroid-induced ONFH by reducing oxidative stress.

Effects of Inhaled Corticosteroids on the Growth Plates of Infant Rats

The most significant adverse effect of inhaled steroid administration in children is suppression of hypothalamic-pituitary-adrenal axis responsiveness and suppression of growth. This study evaluates the effects of inhaled corticosteroids on the growth plates in infant rats. Rats aged 10 days were divided into five groups. Low and high doses of budesonide and fluticasone propionate (50-200-250 mcg/day) were applied with a modified spacer for 10 days. The rat's tibias were then removed and the effects of the steroids on the growth plates were compared. Growth cartilage chondrocyte proliferation and apoptosis rates; IGF-1 and glucocorticoid receptor levels; and resting, proliferative, hypertrophic, and total zone (TZ) measurements were compared using immunohistochemical-staining methods. With high doses of fluticasone, growth plates were affected much more than with high doses of budesonide (p = 0.01). Fluticasone, particularly at a dose of 250 mcg, inhibited the growth plate with an intensive negative impact on all parameters.