The effect of hyperbaric oxygen treatment on aspiration pneumonia

Hyperbaric oxygen therapy: Can it be a novel supportive therapy in COVID-19?

The coronavirus disease 2019 (COVID-19) is a pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV2). Although 85% of infected patients remain asymptomatic, 5% show severe symptoms such as hypoxaemic respiratory failure and multiple end organ dysfunction (MODS) requiring intensive care unit (ICU) admission with a mortality rate of about 2.8%. Since a definitive treatment is yet to be identified, preventive and supportive strategies remain the mainstay of management. Supportive measures such as oxygen therapy with nasal cannula, face mask, noninvasive ventilation, mechanical ventilation and even extreme measures such as extracorporeal membrane oxygenation (ECMO) fail to improve oxygenation in some patients. Hence, hyperbaric oxygen therapy (HBOT) has been proposed as a supportive strategy to improve oxygenation in COVID-19 patients. HBOT is known to increase tissue oxygenation by increasing the amount of dissolved oxygen in plasma. HBOT also mitigates tissue inflammation thus reducing the ill effects of cytokine storm in COVID-19 patients. Though there is limited literature available on HBOT in COVID-19 patients, considering the present need for additional supportive therapy to improve oxygenation, HBOT has been proposed as a novel supportive treatment in COVID-19 patients.

Mesenchymal stem cells alleviate hydrochloric acid-induced lung injury through suppression of inflammation, oxidative stress and apoptosis in comparison to moxifloxacin and sildenafil

Introduction

Acute lung injury (ALI) is a severe life-threatening disease causing uncontrolled pulmonary inflammation and oxidative damage. There are still no effective therapies for this disease. The aim of this study was to evaluate the protective role of mesenchymal stem cells, moxifloxacin, sildenafil or a combination of moxifloxacin and sildenafil against hydrochloric Acid (HCl) - induced ALI.

Methods

HCl or saline was injected intra-tracheally and after 2 h, moxifloxacin, sildenafil, moxifloxacin + sildenafil or mesenchymal stem cells were injected. After 7 days, rats were sacrificed for evaluation of the blood chemistry and inflammation via determination of the level of oxidative stress markers, apoptosis and the histopathological alterations by H&E.

Results

In HCl-injected rats, there were a significant increase in total white blood cells (WBCs), lymphocytes, malondialdehyde (MDA) and caspase-3 gene expression. Also, there were a significant decrease in superoxide dismutase (SOD), catalase (CAT), reduced glutathione (GSH) and Hemeoxygenase-1 (HO-1) gene expression in lung tissue. On the other hand, treatment of lung injured rats with mesenchymal stem cell, moxifloxacin, sildenafil or a combination of moxifloxacin and sildenafil showed a significant decrease in WBCs and lymphocytes and ameliorated the histopathological changes. MDA level in lung tissue was only significantly lowered in rats treated with moxifloxacin alone or in combination with sildenafil or MSCs. GSH was just increased in rats treated with moxifloxacin, sildenafil or with MSCs. Antioxidant parameters and gene expression of HO-1 and caspase-3 were significantly modulated in rats treated with MSCs.

Conclusion

MSCs ameliorated the toxic effects of HCl through their ability to decrease inflammation, oxidative stress, and apoptosis in acute lung injury.

The effect of methylene blue treatment on aspiration pneumonia

BACKGROUND

The study aimed to examine whether methylene blue (MB) prevents different pulmonary aspiration materials-induced lung injury in rats.

METHODS

The experiments were designed in 60 Sprague-Dawley rats, ranging in weight from 250-300 g, randomly allotted into one of six groups (n = 10): saline control, Biosorb Energy Plus (BIO), hydrochloric acid (HCl), saline + MB treated, BIO + MB treated, and HCl + MB treated. Saline, BIO, and HCl were injected into the lungs in a volume of 2 mL/kg. After surgical procedure, MB was administered intraperitoneally for 7 days at a daily dose of 2 mg/kg per day. Seven days later, rats were killed, and both lungs in all groups were examined biochemically and histopathologically.

RESULTS

Our findings show that MB inhibits the inflammatory response reducing significantly (P < 0.05) peribronchial inflammatory cell infiltration, alveolar septal infiltration, alveolar edema, alveolar exudate, alveolar histiocytes, interstitial fibrosis, granuloma, and necrosis formation in different pulmonary aspiration models. Pulmonary aspiration significantly increased the tissue hydroxyproline content, malondialdehyde levels, and decreased (P < 0.05) the antioxidant enzyme (superoxide dismutase and glutathione peroxidase) activities. MB treatment significantly (P < 0.05) decreased the elevated tissue hydroxyproline content and malondialdehyde levels and prevented the inhibition of superoxide dismutase and glutathione peroxidase (P < 0.05) enzymes in the tissues. Furthermore, there is a significant reduction in the activity of inducible nitric oxide synthase (iNOS), terminal deoxynucleotidyl transferase dUTP nick end labeling, and arise in the expression of surfactant protein D in lung tissue of different pulmonary aspiration models with MB therapy.

CONCLUSIONS

MB treatment might be beneficial in lung injury and therefore shows potential for clinical use.

The effects of α-tocopherol on oxidative damage and serum levels of Clara cell protein 16 in aspiration pneumonitis induced by bile acids

Our aim in this study is to examine the effects of α-tocopherol (AT) on rats with aspiration pneumonitis induced with bile acids (BAs). The animals were divided in to four groups, namely saline group ( n = 7), saline + AT group ( n = 7), BA group ( n = 7), and BA + AT group ( n = 7). Saline and BA groups aspirated intratracheally with 1 ml/kg saline and 1 ml/kg bile acids, respectively. AT was given at 20 mg/kg/day dosage for 7 days to the groups. AT group was given 20 mg/kg/day AT for 7 days. Malondialdehyde (MDA), Clara cell protein 16 (CC-16), catalase (CAT), superoxide dismutase (SOD), as well as peribronchial inflammatory cell infiltration, alveolar septal infiltration, alveolar edema, alveolar exudate, alveolar histiocytes, and necrosis were evaluated. The CAT activity of the BA group was significantly lower than the saline group. In the BA + AT group, there was a significant increase in SOD and CAT activities when compared with that of the BA group. The CC-16 and MDA contents in the BA group were significantly higher than in the saline group. The CC-16 and MDA levels of the BA + AT group were significantly lower than BA group. Histopathologic changes were seen in BA group, and there was a significant decrease in the BA + AT group. In conclusion, AT might be beneficial in the treatment of aspiration pneumonitis induced by BAs because AT decreased oxidative damage and resulted in a decrease in CC-16 levels.