Effects of different corticosteroid doses and durations on smoke inhalation-induced acute lung injury and pulmonary fibrosis in the rat

Prophylactic Systemic Antibiotic and Systemic Glucocorticoid Therapy After Burn Inhalation Injury: A Report of Two Cases and Review of Literature

Burn inhalation injury is a significant risk factor for mortality in burn patients. Despite the considerable progress made in the treatment of burn inhalation injury, there remains no consensus on the appropriate course of treatment, leading to ongoing controversy regarding the use of prophylactic systemic antibiotics and systemic glucocorticoids. This study presents two cases of burn inhalation injury diagnosed by fiberoptic bronchoscopy and treated with systemic glucocorticoids and prophylactic systemic antibiotics. By conducting a literature review, this study aimed to discuss the application of systemic glucocorticoids and prophylactic systemic antibiotics in patients with burn inhalation injuries. The suitability of prophylactic systemic antibiotics and systemic glucocorticoids for treating burn inhalation injury patients necessitates a comprehensive assessment of the patient's condition and an accurate judgment of the course of their disease.

Ameliorative Potential of Bone Marrow-Derived Mesenchymal Stem Cells Versus Prednisolone in a Rat Model of Lung Fibrosis: A Histological, Immunohistochemical, and Biochemical Study

Idiopathic pulmonary fibrosis (IPF) is a progressive lung disease of unknown origin with limited treatment options and poor prognosis. The encouraging findings from preclinical investigations utilizing mesenchymal stem cells (MSCs) indicated that they could serve as a promising therapeutic alternative for managing chronic lung conditions, such as IPF. The objective of this study was to compare the efficiency of bone marrow-derived MSCs (BM-MSCs) versus prednisolone, the standard anti-inflammatory medication, in rats with bleomycin (BLM)-induced lung fibrosis. Four groups were created: a control group, a BLM group, a prednisolone-treated group, and a BM-MSCs-treated group. To induce lung fibrosis, 5 mg/kg of BLM was administered intratracheally. BLM significantly increased serum levels of pro-inflammatory cytokines and oxidative stress markers. The disturbed lung structure was also revealed by light and transmission electron microscopic studies. Upregulation in the immune expression of alpha-smooth muscle actin, transforming growth factor beta-1, and Bax was demonstrated. Interestingly, all findings significantly regressed on treatment with prednisolone and BM-MSCs. However, treatment with BM-MSCs showed better results than with prednisolone. In conclusion, BM-MSCs could be a promising approach for managing lung fibrosis.

High Targeting Specificity toward Pulmonary Inflammation Using Mesenchymal Stem Cell-Hybrid Nanovehicle for an Efficient Inflammation Intervention

Pulmonary inflammation is one of the most reported tissue inflammations in clinic. Successful suppression of inflammation is vital to prevent further inevitably fatal lung degeneration. Glucocorticoid hormone, such as methylprednisolone (MP), is the most applied strategy to control the inflammatory progression yet faces the challenge of systemic side effects caused by the requirement of large-dosage and frequent administration. Highly efficient delivery of MP specifically targeted to inflammatory lung sites may overcome this challenge. Therefore, the present study develops an inflammation-targeted biomimetic nanovehicle, which hybridizes the cell membrane of mesenchymal stem cell with liposome, named as MSCsome. This hybrid nanovehicle shows the ability of high targeting specificity toward inflamed lung cells, due to both the good lung endothelium penetration and the high uptake by inflamed lung cells. Consequently, a single-dose administration of this MP-loaded hybrid nanovehicle achieves a prominent treatment of lipopolysaccharide-induced lung inflammation, and negligible treatment-induced side effects are observed. The present study provides a powerful inflammation-targeted nanovehicle using biomimetic strategy to solve the current challenges of targeted inflammation intervention.

Protective effects of methylprednisolone-cyclophosphamide treatment on bleomycin-induced pulmonary fibrosis

BACKGROUND

Methylprednisolone (MP) and cyclophosphamide (CTX) combination treatment has shown great benefits in improving pulmonary fibrosis (PF) and high safety. Currently, the mechanism underlying the effects of MP-CTX on improving PF remains unclear. This study determined the effects of MP-CTX combination treatment on the modulation of inflammation, oxidative stress, and T-cell immunity in PF.

METHODS

PF rat models were induced by bleomycin stimulation. MP (3 mg/kg) and MP-CTX (MP: 3 mg/kg; CTX: 8 mg/kg) combination were administered in the PF + MP and PF + MP + CTX groups, respectively. Transmission electron microscopy, hematoxylin and eosin staining, Ashcroft score, and Masson trichrome staining were performed to measure lung morphology in PF. Enzyme-linked immunosorbent assay and quantitative polymerase chain reaction assay were performed to quantify inflammatory factors. Malondialdehyde (MDA), superoxide dismutase (SOD), and glutathione peroxidase (GSH-PX) levels were determined using commercial kits. α-Smooth muscle actin (SMA) and collagen I levels were determined using western blotting and immunohistochemistry. The T-cell count was evaluated using flow cytometry.

RESULTS

MP-CTX reduced lung injury, collagen deposition, and α-SMA and collagen I levels in a bleomycin-induced PF rat model. Additionally, MP-CTX decreased the levels of MDA and inflammatory factors (tumor necrosis factor-α, interleukin-1β, and interleukin-6) but increased the activities of SOD and GSH-PX. Furthermore, MP-CTX changed T-cell types in lung tissues, such as increasing CD4⁺CD25⁺Foxp3⁺ cell count.

CONCLUSIONS

MP-CTX combination treatment improved the degree of PF by reducing inflammation and oxidative stress and improving T-cell immunity. These findings provide novel insights into the mechanisms underlying the effects of MP-CTX on PF.

Role of Mesenchymal Stem Cells and Extracellular Vesicles in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive interstitial fibrotic disease that leads to disability and death within 5 years of diagnosis. Pulmonary fibrosis is a disease with a multifactorial etiology. The concept of aberrant regeneration of the pulmonary epithelium reveals the pathogenesis of IPF, according to which repeated damage and death of alveolar epithelial cells is the main mechanism leading to the development of progressive IPF. Cell death provokes the migration, proliferation and activation of fibroblasts, which overproduce extracellular matrix, resulting in fibrotic deformity of the lung tissue. Mesenchymal stem cells (MSCs) and extracellular vesicles (EVs) are promising therapies for pulmonary fibrosis. MSCs, and EVs derived from MSCs, modulate the activity of immune cells, inhibit the expression of profibrotic genes, reduce collagen deposition and promote the repair of damaged lung tissue. This review considers the molecular mechanisms of the development of IPF and the multifaceted role of MSCs in the therapy of IPF. Currently, EVs-MSCs are regarded as a promising cell-free therapy tool, so in this review we discuss the results available to date of the use of EVs-MSCs for lung tissue repair.

Effects of different doses of methylprednisolone therapy on acute respiratory distress syndrome: results from animal and clinical studies

Background

The optimal dose of glucocorticoids for acute respiratory distress syndrome (ARDS) is uncertain. This study aimed to evaluate the effects of different doses of methylprednisolone on sepsis-induced acute lung injury (ALI) rats and a cohort of moderate and severe ARDS patients.

Methods

ALI rats, challenged with lipopolysaccharide, were randomly received intraperitoneal injection of normal saline (model group) and different doses of methylprednisolone (0.5, 2, 8 mg/kg, named as low-, moderate- and high-dose group, respectively) for 5 days. The body weight changes of rats, inflammatory factors in bronchoalveolar lavage fluid (BALF), lung wet/dry ratio, histopathological score, and the mRNA expressions of glucocorticoid receptor α (GRα), GRβ and nuclear factor-κB (NF-κB) were measured. Forty moderate and severe ARDS patients were treated with standard of care or plus different doses of methylprednisolone (40, 80, 120 mg/day, named as low-, moderate- and high-dose group, respectively) for 5 days. Clinical outcomes were PaO₂/FiO₂ ratio and C-reactive protein (CRP) level at day 5, intubation rate, hospital stay, 28-day mortality, and adverse events rate.

Results

In animal experiment, different doses of methylprednisolone could increase the body weight of rats, and reduce inflammatory factors in BALF and the degree of lung injury compared with model group. The efficacy of methylprednisolone at moderate-dose was better than that at low-dose, but was equivalent to that at high-dose, which was consistent with the differential changes in the mRNA expression of GRα, GRβ and NF-κB. In clinical study, the moderate-dose group was associated with higher PaO₂/FiO₂ ratio and lower CRP level. No significant difference in other clinical outcomes among groups was detected.

Conclusions

This study showed that the efficacy of methylprednisolone in ARDS treatment was not always dose-dependent due to the differential regulation of related receptors. The moderate-dose of methylprednisolone may be the potential optimal dose for ARDS treatment, which needs to be further verified by larger clinical trials.

Therapeutic effect of pH-Responsive dexamethasone prodrug nanoparticles on acute lung injury

Acute lung injury/inflammation (ALI) is usually caused by various injury factors inside and outside the lung, which can be transformed into acute respiratory distress syndrome (ARDS) in severe cases. Alveolar macrophages play a key role in the pathogenesis of ALI, which regulate inflammatory responses by secreting inflammatory mediators. Therefore, we prepared dexamethasone (DXM)/mannose co-modified branched polyethyleneimine (PEI) (DXM-PEI-mannose, DPM) prodrug nanopartcales, which could effectively target the mannose receptor (MR) on the surface of alveolar macrophages and be used for the treatment of ALI. The DXM-PEI (DP) prodrug was obtained by linking DXM with branched PEI through Schiff base reaction. Subsequently, the pH-responsive DPM prodrug was obtained by using mannose-targeted head modification. The DPM prodrug NPs with a particle size of 115 ± 1 nm, a polydispersity index (PDI) value of 0.054 ± 0.018, and a zeta potential of 31 ± 1 mV were obtained by cross-linking. The drug loading of DPM prodrug NPs measured by the acid hydrolysis method was 51.88%, which had good serum stability and biocompatibility. By comparing the stability and property release of prodrug NPs under different pH (7.4 and 5.0) conditions, it showed that DPM prodrug NPs had certain sensitivity to the micro-acid environment. To study the targeting of mouse mononuclear macrophages, mannose-modified prodrug NPs showed significant in vitro targeting. Moreover, prodrug NPs showed good anti-inflammatory activity in vitro, which was significantly different from free drugs. In vivo biodistribution experiments also showed that it had a long-term lung targeting effect. DPM prodrug NPs also had a good therapeutic effect on ALI. In conclusion, the mannose-modified DXM prodrug NPs delivery system could specifically target lung tissues and have a good therapeutic effect, which might be useful for the treatment of lung diseases.

Pulmonary coagulation and fibrinolysis abnormalities that favor fibrin deposition in the lungs of mouse antibody-mediated transfusion-related acute lung injury

Transfusion-related acute lung injury (TRALI) is a life-threatening disease caused by blood transfusion. However, its pathogenesis is poorly understood and specific therapies are not available. Experimental and clinical studies have indicated that alveolar fibrin deposition serves a pathological role in acute lung injuries. The present study investigated whether pulmonary fibrin deposition occurs in a TRALI mouse model and the possible mechanisms underlying this deposition. The TRALI model was established by priming male Balb/c mice with lipopolysaccharide (LPS) 18 h prior to injection of an anti-major histocompatibility complex class I (MHC-I) antibody. Untreated mice and mice administered LPS plus isotype antibody served as controls. At 2 h after TRALI induction, blood and lung tissue were collected. Disease characteristics were assessed based on lung tissue histology, inflammatory responses and alterations in the alveolar-capillary barrier. Immunofluorescence staining was used to detect pulmonary fibrin deposition, platelets and fibrin-platelet interactions. Levels of plasminogen activator inhibitor-1 (PAI-1), thrombin-antithrombin complex (TATc), tissue factor pathway inhibitor (TFPI), coagulation factor activity and fibrin degradation product (FDP) in lung tissue homogenates were measured. Severe lung injury, increased inflammatory responses and a damaged alveolar-capillary barrier in the LPS-primed, anti-MHC-I antibody-administered mice indicated that the TRALI model was successfully established. Fibrin deposition, fibrin-platelet interactions and platelets accumulation in the lungs of mouse models were clearly promoted. Additionally, levels of TATc, coagulation factor V (FV), TFPI and PAI-1 were elevated, whereas FDP level was decreased in TRALI mice. In conclusion, both impaired fibrinolysis and enhanced coagulation, which might be induced by boosted FV activity, increased pulmonary platelets accumulation and enhanced fibrin-platelet interactions and contributed to pulmonary fibrin deposition in TRALI mice. The results provided a therapeutic rationale to target abnormalities in either coagulation or fibrinolysis pathways for antibody-mediated TRALI.

Construction of mannose-modified polyethyleneimine-block-polycaprolactone cationic polymer micelles and its application in acute lung injury

This study evaluated the D-mannose modified polyethyleneimine-block-polycaprolactone biomacromolecule copolymer micelles (PCL-PEI-mannose) as a targeted delivery of the glucocorticoid dexamethasone (DXM) to lung inflammation tissues and enhances the vehicle for its anti-inflammatory effects. Dexamethasone was encapsulated in the hydrophobic core of cationic polymer micelles by solvent evaporation. The polymeric micelles exhibited sustained-release within 48 h, good blood compatibility, and colloidal stability in vitro. The cellular uptake of mannose-modified micelles was higher compared with the non-modified micelles. And drug-loaded targeted micelles could inhibit the production of inflammatory factors in activated RAW264.7 cells. The distribution results indicated that drug-loaded targeted micelles highly improved the lung targeting ability, reduced the wet/dry ratio of injured lung tissue, and relieved the lung inflammation, accompanied by the decrease of inflammatory cell infiltration, myeloperoxidase activity, and inflammatory mediator levels in bronchoalveolar lavage fluid. These findings suggested that PCL-PEI-mannose delivery system could facilitate the lung-specific delivery and inhibit the inflammatory response. Collectively, PCL-PEI-mannose polymer micelles could be used as a potential delivery system for the treatment of acute lung injury (ALI).

MHTP, a synthetic alkaloid, attenuates combined allergic rhinitis and asthma syndrome through downregulation of the p38/ERK1/2 MAPK signaling pathway in mice

The combined allergic rhinitis and asthma syndrome (CARAS) is a chronic airway inflammation of allergic individuals, with a type 2 immune response. Pharmacotherapy is based on drugs with relevant side effects. Thus, the goal of this study was to evaluate the synthetic alkaloid, MHTP in the experimental model of CARAS. Therefore, BALB/c mice were ovalbumin (OVA) -sensitized and -challenged and treated with MHTP by intranasal or oral routes. Treated animals showed a decrease (p < 0.05) of sneezing, nasal rubbings, and histamine nasal hyperactivity. Besides, MHTP presented binding energy and favorable interaction for adequate anchoring in the histamine H1 receptor. MHTP treatment inhibited the eosinophil migration into the nasal (NALF) and the bronchoalveolar (BALF) fluids. Histological analysis showed that the alkaloid decreased the inflammatory cells in the subepithelial and perivascular regions of nasal tissue and in the peribronchiolar and perivascular regions of lung tissue. The MHTP treatment also reduced the pulmonary hyperactivity by decreasing the smooth muscle layer hypertrophy and the collagen fiber deposition in the extracellular matrix. The immunomodulatory effect of the alkaloid was due to the decrease of cytokines like IL-5 and IL-17A (type 2 and 3), TSLP (epithelial), and the immunoregulatory cytokine, TGF-β. These MHTP effects on granulocytes were dependent on the p38/ERK1/2 MAP kinase signaling pathway axis. Indeed, the synthetic alkaloid reduced the frequency of activation of both kinases independent of the NF-κB (p65) pathway indicating that the molecule shut down the intracellular transduction signals underlie the cytokine gene transcription.

Efficacy and safety of low-dose corticosteroids for acute respiratory distress syndrome: A systematic review and meta-analysis

BACKGROUND

There are conflicting results regarding whether corticosteroids have better efficacy than placebo in acute respiratory distress syndrome (ARDS) patients. Therefore, we aim to further evaluate the efficacy and safety of corticosteroids in adult ARDS patients.

METHODS

The databases, including Medline, EMBASE, and Cochrane Central Register of Controlled Trials (CENTRAL) in the Cochrane Library, were searched from their inception to May 2, 2020. Randomized controlled trials (RCTs) and observational cohort studies were selected to assess the use of corticosteroids in adult ARDS patients. The quality of the results was judged by the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology. The inverse-variance method with random or fixed effects modeling was used to compute pooled odds ratio (OR), standardized mean difference (SMD), and their 95% confidence interval (CI).

RESULTS

Eight eligible RCTs and six cohort studies were included. The use of corticosteroids was associated with reduced mortality (OR 0.57, 95% CI 0.43-0.76, I2=35.1%, P=0.148) in ARDS patients, and the result was confirmed in the included cohort studies (OR 0.51, 95% CI 0.27-0.95, I2=66.7%, P=0.010). The subgroup analysis stratified by the initiation time and duration of corticosteroid use showed that early ARDS and prolonged corticosteroid use had significant survival benefits in the RCTs. The low-dose corticosteroid use was also associated with significantly more ventilator-free days and a reduced rate of new infections in ARDS patients.

CONCLUSIONS

The low-dose corticosteroid therapy may be safe and reduce mortality, especially in patients with prolonged treatment and early ARDS.

Hypoxia-Inducible Factor-1: A Potential Target to Treat Acute Lung Injury

Acute lung injury (ALI) is an acute hypoxic respiratory insufficiency caused by various intra- and extrapulmonary injury factors. Presently, excessive inflammation in the lung and the apoptosis of alveolar epithelial cells are considered to be the key factors in the pathogenesis of ALI. Hypoxia-inducible factor-1 (HIF-1) is an oxygen-dependent conversion activator that is closely related to the activity of reactive oxygen species (ROS). HIF-1 has been shown to play an important role in ALI and can be used as a potential therapeutic target for ALI. This manuscript will introduce the progress of HIF-1 in ALI and explore the feasibility of applying inhibitors of HIF-1 to ALI, which brings hope for the treatment of ALI.

A comparative study of a preclinical survival model of smoke inhalation injury in mice and rats

Smoke inhalation injury increases morbidity and mortality. Clinically relevant animal models are necessary for the continued investigation of the pathophysiology of inhalation injury and the development of therapeutics. The goal of our research was threefold: 1) to develop a reproducible survival model of smoke inhalation injury in rats that closely resembled our previous mouse model, 2) to validate the rat smoke inhalation injury model using a variety of laboratory techniques, and 3) to compare and contrast our rat model with both the well-established mouse model and previously published rat models to highlight our improvements on smoke delivery and lung injury. Mice and rats were anesthetized, intubated, and placed in custom-built smoke chambers to passively inhale woodchip-generated smoke. Bronchoalveolar lavage fluid (BALF) and lung tissue were collected for confirmatory tests. Lung sections were hematoxylin and eosin stained, lung edema was assessed with wet-to-dry (W/D) ratio, and inflammatory cell infiltration and cytokine elevation were evaluated using flow cytometry, immunohistochemistry, and ELISA. We confirmed that our mouse and rat models of smoke inhalation injury mimic the injury seen after human burn inhalation injury with evidence of pulmonary edema, neutrophil infiltration, and inflammatory cytokine elevation. Interestingly, rats mounted a more severe immunological response compared with mice. In summary, we successfully validated a reliable and clinically translatable survival model of lung injury and immune response in rats and mice and characterized the extent of this injury. These animal models allow for the continued study of smoke inhalation pathophysiology to ultimately develop a better therapeutic.

BMSC-derived exosomes alleviate smoke inhalation lung injury through blockade of the HMGB1/NF-κB pathway

AIMS

To investigate the role of bone marrow mesenchymal stem cell (BMSC)-derived exosomes in smoke inhalation lung injury.

MAIN METHODS

In this study, we initially isolated exosomes from BMSCs and identified them by western blot and transmission electron microscopy. BMSC-derived exosomes were then used to treat in vitro and in vivo models of smoke inhalation lung injury. Pathologic alterations in lung tissue, the levels of inflammatory factors and apoptosis-related factors, and the expression of HMGB1 and NF-κB were determined to evaluate the therapeutic effect of BMSC-derived exosomes.

KEY FINDINGS

We found that BMSC-derived exosomes could alleviate the injury caused by smoke inhalation. Smoke inhalation increased the levels of inflammatory factors and apoptosis-related factors and the expression of HMGB1 and NF-κB, and these increases were reversed by BMSC-derived exosomes. HMGB1 overexpression abrogated the exosome-induced decreases in inflammatory factors, apoptosis-related factors and NF-κB.

SIGNIFICANCE

Collectively, these results indicate that BMSC-derived exosomes can effectively alleviate smoke inhalation lung injury by inhibiting the HMGB1/NF-κB pathway, suggesting that exosome, a noncellular therapy, is a potential therapeutic strategy for inhalation lung injury.

Effectiveness of glucocorticoid therapy in patients with severe coronavirus disease 2019: protocol of a randomized controlled trial

BACKGROUND

At the end of 2019, a novel coronavirus outbreak causative organism has been subsequently designated the 2019 novel coronavirus (2019-nCoV). The effectiveness of adjunctive glucocorticoid therapy in the management of 2019-nCoV-infected patients with severe lower respiratory tract infections is not clear, and warrants further investigation.

METHODS

The present study will be conducted as an open-labeled, randomized, controlled trial. We will enrol 48 subjects from Chongqing Public Health Medical Center. Each eligible subject will be assigned to an intervention group (methylprednisolone via intravenous injection at a dose of 1-2 mg/kg/day for 3 days) or a control group (no glucocorticoid use) randomly, at a 1:1 ratio. Subjects in both groups will be invited for 28 days of follow-up which will be scheduled at four consecutive visit points. We will use the clinical improvement rate as our primary endpoint. Secondary endpoints include the timing of clinical improvement after intervention, duration of mechanical ventilation, duration of hospitalization, overall incidence of adverse events, as well as rate of adverse events at each visit, and mortality at 2 and 4 weeks.

DISCUSSION

The present coronavirus outbreak is the third serious global coronavirus outbreak in the past two decades. Oral and parenteral glucocorticoids have been used in the management of severe respiratory symptoms in coronavirus-infected patients in the past. However, there remains no definitive evidence in the literature for or against the utilization of systemic glucocorticoids in seriously ill patients with coronavirus-related severe respiratory disease, or indeed in other types of severe respiratory disease. In this study, we hope to discover evidence either supporting or opposing the systemic therapeutic administration of glucocorticoids in patients with severe coronavirus disease 2019.

TRIAL REGISTRATION

ClinicalTrials.gov, ChiCTR2000029386, http://www.chictr.org.cn/showproj.aspx?proj=48777.