Effects of Human Interleukin-10 on Ventilator-Associated Lung Injury in Rats

The Wnt/β-catenin pathway regulates inflammation and apoptosis in ventilator-induced lung injury

Ventilator-induced lung injury (VILI) may be caused by incorrect mechanical ventilation (MV), and its progression is mainly related to inflammatory reaction, apoptosis, and oxidative stress. The Wnt/β-catenin pathway can modulate inflammation and apoptosis; however, its role in VILI is unknown. This research aims to explore the role of the Wnt/β-catenin pathway in VILI. VILI models were established using rats and type II alveolar epithelial (ATII) cells. Glycogen synthase kinase 3β (GSK-3β), β-catenin, and cyclin D1 were determined using western blotting and immunofluorescence. Apoptosis of lung tissues was evaluated using TUNEL, flow cytometry, Bax, and Bcl2 protein. Interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) were detected via enzyme-linked immunosorbent assay (ELISA). Lung pathological injury was evaluated through hematoxylin and eosin (H&E) staining. Lung permeability was evaluated by the ratio of dry to wet weight of lung tissue and the total protein level of bronchoalveolar lavage fluid (BALF). The results showed that GSK-3β expression was enhanced and β-catenin expression was diminished in lung tissue under MV. SB216763 increased β-catenin and cyclin D1 expression by inhibiting GSK-3β expression and inhibited the inflammatory response and apoptosis of lung, alleviated pulmonary edema and lung tissue permeability, and significantly mitigated lung injury. However, inhibition of β-catenin expression by MSAB attenuated the anti-inflammatory and antiapoptotic effects of SB216763 in VILI. Overall, the present study demonstrates that the Wnt/β-catenin pathway activation in MV may play an anti-inflammatory and antiapoptotic role, thereby alleviating lung injury and delaying VILI progression, which may be a key point of intervention in VILI.

Identifying biomarkers of ventilator induced lung injury during one-lung ventilation surgery: a scoping review

BACKGROUND

Ventilator-induced lung injury (VILI) can occur as a result of mechanical ventilation to two lungs. Thoracic surgery often requires one-lung ventilation (OLV). The potential for VILI is likely higher in OLV. The impact of OLV on development of post-operative pulmonary complications is not well understood. We aimed to perform a scoping review to determine reliable biomarkers of VILI after OLV.

METHODS

A scoping review was performed using Cochrane Collaboration methodology. We searched Medline, EMBASE and SCOPUS. Gray literature was searched. Studies of adult human or animal models without pre-existing lung damage exposed to OLV, with biomarker responses analyzed were included.

RESULTS

After screening 5,613 eligible papers, 89 papers were chosen for full text review, with 29 meeting inclusion. Approximately half (52%, n=15) of studies were conducted in humans in an intra-operative setting. Bronchoalveolar lavage (BAL) & serum analyses with enzyme-linked immunosorbent assay (ELISA)-based assays were most commonly used. The majority of analytes were investigated by a single study. Of the analytes that were investigated by two or more studies (n=31), only 16 were concordant in their findings. Across all sample types and studies 84% (n=66) of the 79 inflammatory markers and 75% (n=6) of the 8 anti-inflammatory markers tested were found to increase. Half (48%) of all studies showed an increase in TNF-α or IL-6.

CONCLUSIONS

A scoping review of the state of the evidence demonstrated that candidate biomarkers with the most evidence and greatest reliability are general markers of inflammation, such as IL-6 and TNF-α assessed using ELISA assays. Studies were limited in the number of biomarkers measured concurrently, sample size, and studies using human participants. In conclusion these identified markers can potentially serve as outcome measures for studies on OLV.

Coronavirus disease 2019 (COVID-19): cytokine storms, hyper-inflammatory phenotypes, and acute respiratory distress syndrome

Coronavirus Disease 2019 (COVID-19) was first identified in China at the end of 2019. Acute respiratory distress syndrome (ARDS) represents the most common and serious complication of COVID-19. Cytokine storms are a pathophysiological feature of COVID-19 and play an important role in distinguishing hyper-inflammatory subphenotypes of ARDS. Accordingly, in this review, we focus on hyper-inflammatory host responses in ARDS that play a critical role in the differentiated development of COVID-19. Furthermore, we discuss inflammation-related indicators that have the potential to identify hyper-inflammatory subphenotypes of COVID-19, especially for those with a high risk of ARDS. Finally, we explore the possibility of improving the quality of monitoring and treatment of COVID-19 patients and in reducing the incidence of critical illness and mortality via better distinguishing hyper- and hypo-inflammatory subphenotypes of COVID-19.

Endothelial Damage in Acute Respiratory Distress Syndrome

The pulmonary endothelium is a metabolically active continuous monolayer of squamous endothelial cells that internally lines blood vessels and mediates key processes involved in lung homoeostasis. Many of these processes are disrupted in acute respiratory distress syndrome (ARDS), which is marked among others by diffuse endothelial injury, intense activation of the coagulation system and increased capillary permeability. Most commonly occurring in the setting of sepsis, ARDS is a devastating illness, associated with increased morbidity and mortality and no effective pharmacological treatment. Endothelial cell damage has an important role in the pathogenesis of ARDS and several biomarkers of endothelial damage have been tested in determining prognosis. By further understanding the endothelial pathobiology, development of endothelial-specific therapeutics might arise. In this review, we will discuss the underlying pathology of endothelial dysfunction leading to ARDS and emerging therapies. Furthermore, we will present a brief overview demonstrating that endotheliopathy is an important feature of hospitalised patients with coronavirus disease-19 (COVID-19).

The effects of different ventilatory modes in female adult rats submitted to mechanical ventilation

This study aimed to analyze the effects of volume-controlled ventilation (VCV) and pressure-controlled ventilation (PCV) modes in female Wistar rats. 18 Wistar female adult rats were divided into three groups: control (CG), pressure-controlled ventilation (PCVG), and volume-controlled ventilation (VCVG). PCVG and VCVG were submitted to MV for one hour with a tidal volume (TV) of 8 mL/Kg, respiratory rate of 80 breaths/min, and positive end-expiratory pressure of 0 cmH₂O. At the end of the experiment, all animals were euthanized. The neutrophils and lymphocytes influx to lung were higher in VCVG and PCVG compared to CG. The activities of superoxide dismutase, catalase and myeloperoxidase were higher in PCVG compared to CG. There was an increase in lipid peroxidation and protein oxidation in PCVG compared to CG. The levels of CCL3 and CCL5 were higher in PCVG compared to CG. In conclusions, the PCV mode promoted structural changes in the lung parenchyma, redox imbalance and inflammation in healthy adult female rats submitted to MV.

Sigh maneuver protects healthy lungs during mechanical ventilation in adult Wistar rats

Mechanical ventilation (MV) is a tool used for the treatment of patients with acute or chronic respiratory failure. However, MV is a non-physiological resource, and it can cause metabolic disorders such as release of pro-inflammatory cytokines and production of reactive oxygen species. In clinical setting, maneuvers such as sigh, are used to protect the lungs. Thus, this study aimed to evaluate the effects of sigh on oxidative stress and lung inflammation in healthy adult Wistar rats submitted to MV. Male Wistar rats were divided into four groups: control (CG), mechanical ventilation (MVG), MV set at 20 sighs/h (MVG20), and MV set at 40 sighs/h (MVG40). The MVG, MVG20, and MVG40 were submitted to MV for 1 h. After the protocol, all animals were euthanized and the blood, bronchoalveolar lavage fluid, and lungs were collected for subsequent analysis. In the arterial blood, MVG40 presented higher partial pressure of oxygen and lower partial pressure of carbon dioxide compared to control. The levels of bicarbonate in MVG20 were lower compared to CG. The neutrophil influx in bronchoalveolar lavage fluid was higher in the MVG compared to CG and MVG40. In the lung parenchyma, the lipid peroxidation was higher in MVG compared to CG, MVG20, and MVG40. Superoxide dismutase and catalase activity were higher in MVG compared to CG, MVG20, and MVG40. The levels of IL-1, IL-6, and TNF in the lung homogenate were higher in MVG compared to CG, MVG20, and MVG40. The use of sigh plays a protective role as it reduced redox imbalance and pulmonary inflammation caused by MV.

Progranulin Improves Acute Lung Injury through Regulating the Differentiation of Regulatory T Cells and Interleukin-10 Immunomodulation to Promote Macrophage Polarization

Progranulin (PGRN), which plays an anti-inflammatory role in acute lung injury (ALI), is promising as a potential drug. Studies have shown that regulatory T cells (Tregs) and interleukin- (IL-) 10 can repress inflammation and alleviate tissue damage during ALI. In this study, we built a lipopolysaccharide- (LPS-) induced ALI mouse model to illustrate the effect of PGRN on regulation of Treg differentiation and modulation of IL-10 promoting macrophage polarization. We found that the proportion of Tregs in splenic mononuclear cells and peripheral blood mononuclear cells was higher after treatment with PGRN. The increased proportion of Tregs after PGRN intratracheal instillation was consistent with the decreased severity of lung injury, the reduction of proinflammatory cytokines, and the increase of anti-inflammatory cytokines. In vitro, the percentages of CD4⁺CD25⁺FOXP3⁺ Tregs from splenic naïve CD4⁺ T cells increased after PGRN treatment. In further research, it was found that PGRN can regulate the anti-inflammatory factor IL-10 and affect the polarization of M1/M2 macrophages by upregulating IL-10. These findings show that PGRN likely plays a protective role in ALI by promoting Treg differentiation and activating IL-10 immunomodulation.

Candida albicans-induced acute lung injury through activating several inflammatory signaling pathways in mice

Candida albicans infection-induced acute lung injury is one of the most prevalent diseases in immunosuppressive individual. Nevertheless, the mechanism by which Candida albicans induced acute lung injury remains unclear. The present study investigated the mechanism by which Candida albicans induced acute lung injury in mice. Mice were randomly divided into four groups and intratracheally injected with 60 μl Candida albicans (10⁶ CFU) or normal saline. Half of the mice were sacrificed at 6 h after Candida albicans. The rest of the mice for survival test were observed until 7 d after Candida albicans. As expected, immunosuppression aggravated Candida albicans-induced acute lung injury and death in mice. Additionally, Candida albicans infection elevated mRNA levels of pro-inflammatory and chemokines in lungs and the levels of IL-6, IL-1β and IL-17 in serum. Further study showed that Candida albicans promoted nuclear translocation of NF-κB p50 and p65 subunits in pulmonary epithelial cells and interstitial cells. Candida albicans induced pulmonary p38, ERK1/2 and Akt phosphorylation in normal and immunosuppressive mice. Moreover, Candida albicans infection activated pulmonary STAT3 signaling in normal and immunosuppressive mice. Overall, these results suggest that Candida albicans induced acute lung injury and death may be through activating several inflammatory signaling pathways.