Biocompatible N-acetyl-nanoconstruct alleviates lipopolysaccharide-induced acute lung injury in vivo

Intermittent fasting attenuates lipopolysaccharide-induced acute lung injury in mice by modulating macrophage polarization

Acute lung injury (ALI) is a spectrum of acute and life-threatening pulmonary inflammatory conditions. Treatment of ALI remains a clinical challenge. Recently, intermittent fasting (IF) has been shown to improve health and alleviate many diseases. In this study, we tested whether IF attenuated ALI and investigated the mechanism underlying this process. In vivo, the effects of IF on ALI were evaluated in a lipopolysaccharide (LPS)-induced murine ALI model. We found that two times of 24-h fasting in a week before ALI efficiently ameliorated LPS-induced lung injury in mice, characterized by alleviated lung lesions, wet-to-dry weight ratio, myeloperoxidase activity, malondialdehyde content, and lower levels of tumor necrosis factor-α, interleukin-6, and interleukin-1β. In vitro, functional assays were conducted to assess IF on the inflammatory response and macrophage polarization of bone marrow-derived macrophages (BMDMs) treated with LPS or IL-4. And PPARγ antagonist GW9662 and AMPK siRNA were used to test the role of PPARγ and AMPK in the IF-mediated improvement of ALI. The results showed that IF (serum deprivation) suppressed macrophage M1 activation and promoted M2 activation in LPS-treated BMDMs. While, IF also augmented macrophage M2 polarization in IL-4-treated BMDMs. Further mechanistic studies showed that the promotive effect of IF on M2 polarization was related to the activation of the PPARγ and AMPK pathways. In conclusion, this study suggests that IF enhances M2 polarization by activating the AMPK and PPARγ pathways, thus facilitating anti-inflammatory response and ameliorating ALI.

The Role of Antioxidant Agent (N-Acetylcysteine) in Oleic Acid-Induced Acute Lung Injury in a Rat Model

Context

Reactive oxygen species (ROS) produced by inflammatory cells play a major role in mediating lung injury in sepsis or hyperoxic lung injury.

Aims

N-Acetylcysteine (NAC), an antioxidant, was examined in this research to see whether it helps prevent acute lung injury (ALI).

Materials and methods

Experiments were performed on Charles-Foster strain healthy male adult albino rats. All the animals were randomly divided into one control and two experimental groups. In control/group I, saline was administered, and cardiorespiratory parameters were recorded. Oleic acid (OA) was administered in group II to produce ALI. In group III, OA was administered to NAC-pretreated rats, and cardiorespiratory parameters were recorded to observe the effect of NAC on ALI. This study used analysis of variance (ANOVA) with two factors and a post hoc test (multiple comparisons - least significant difference (LSD) test) for statical analysis. For determining survival time, the Mantel-Cox test and Kaplan-Meier survival curves were used. A P value < 0.05 was considered significant.

Results

Respiratory arrest, pulmonary edema, and reduced partial pressure of oxygen (PaO₂)/fraction of inspired oxygen (FiO₂) ratio were all indications of OA-induced ALI in rats. The animals in the NAC + OA group had better respiratory and cardiac statistics than those in the OA alone group, and their survival duration was extended. However, NAC pretreatment could not protect the animals against the development of pulmonary edema.

Conclusions

These observations indicate that NAC (an antioxidant agent) protected rats against ALI in the initial phase and prolonged the survival time but failed to prevent the development of pulmonary edema.