Instilled air promotes lipopolysaccharide-induced acute lung injury

Sea Cucumber and Blueberry Extracts Suppress Inflammation and Reduce Acute Lung Injury through the Regulation of NF-κB/MAPK/JNK Signaling Pathway in Lipopolysaccharide-Treated C57BL/6 Mice

Acute lung injury (ALI) represents a life-threatening condition with high morbidity and mortality despite modern mechanical ventilators and multiple pharmacological strategies. Therefore, there is a need to develop efficacious interventions with minimal side effects. The anti-inflammatory activities of sea cucumber (Cucumaria frondosa) and wild blueberry (Vaccinium angustifolium) extracts have been reported recently. However, their anti-inflammatory activities and the mechanism of action against ALI are not fully elucidated. Thus, the present study aims to understand the mechanism of the anti-inflammatory activity of sea cucumber and wild blueberry extracts in the context of ALI. Experimental ALI was induced via intranasal lipopolysaccharide (LPS) instillation in C57BL/6 mice and the anti-inflammatory properties were determined by cytokine analysis, histological examination, western blot, and qRT-PCR. The results showed that oral supplementation of sea cucumber extracts repressed nuclear factor kappa B (NF-κB) and mitogen-activated protein kinase (MAPK) signaling pathways, thereby downregulating the expression of interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF) in the lung tissue and in the plasma. Wild blueberry extracts also suppressed the expression of IL-4. Furthermore, the combination of sea cucumber and wild blueberry extracts restrained MAPK signaling pathways by prominent attenuation of phosphorylation of NF-κB, c-Jun N-terminal kinase (JNK), and extracellular signal-regulated kinase (ERK) while the levels of pro-inflammatory cytokines were significantly suppressed. Moreover, there was a significant and synergistic reduction in varying degrees of ALI lesions such as distorted parenchyma, increased alveoli thickness, lymphocyte and neutrophil infiltrations, fibrin deposition, pulmonary emphysema, pneumonia, intra-alveolar hemorrhage, and edema. The anti-inflammatory effect of the combination of sea cucumber and wild blueberry extracts is associated with suppressing MAPK and NF-κB signaling pathways, thereby significantly reducing cytokine storm in LPS-induced experimental ALI.

Sodium Butyrate Inhibits the Inflammation of Lipopolysaccharide-Induced Acute Lung Injury in Mice by Regulating the Toll-Like Receptor 4/Nuclear Factor κB Signaling Pathway

Bacterial pneumonia is a common disease in dairy herds worldwide, which brings great economic losses to farmers. Sodium butyrate (SB), an inhibitor of histone deacetylase, plays an important role in limiting inflammation. The purpose of this study was to investigate the protective effects of SB on lipopolysaccharide (LPS)-induced acute lung injury (ALI) in mice and explore the potential mechanism of SB protection. A total of 30 ICR mice were randomly divided into three groups ( n = 10): a phosphate-buffered saline (PBS) intratracheal instillation group, a LPS intratracheal instillation group, and a SB gavage group (SB was given 1 h before the LPS stimulation). After 12 h, samples of the blood and lung tissue were collected from the mice for experimental analysis. The results showed that the concentration of inflammatory cytokines [interleukin 1β (IL1β) and tumor necrosis factor α (TNF-α)], myeloperoxidase (MPO) activity in the lung tissue and blood, protein abundance of toll-like receptor 4 (TLR4), nuclear factor κB (NF-κB, p65), phosphorylated p65 (p-p65), inhibitor κBα (IκBα), and phosphorylated IκBα (p-IκBα), and relative mRNA expression of genes associated with inflammation, such as TLR4, NF-κB, IL1β, interleukin 6 (IL6), and TNF-α, were significantly upregulated in the LPS group compared to the PBS group. However, the SB addition markedly downregulated the levels of these parameters in the LSB group compared to those in the LPS group. Furthermore, the structure of the lung tissue from the LPS group was severely disrupted in comparison to that of the PBS group. However, with SB administration, the severe structural disruption was relieved. In addition, an immunohistochemical analysis showed that positive immunoreactions to TLR4, p65, and TNF-α were significant in the LPS group; however, SB addition markedly attenuated this phenomenon. In conclusion, the ALI mouse model was successfully established with an intratracheal instillation of LPS. Furthermore, gavage with SB inhibited inflammation in LPS-induced ALI.

Milonine, an Alkaloid of Cissampelos sympodialis Eichl. (Menispermaceae) Inhibits Histamine Release of Activated Mast Cells

Milonine is an alkaloid of Cissampelos sympodialis Eichl. (Menispermaceae), a plant used in the northeast of Brazil to treat allergies such as asthma, rhinitis, and other conditions. Previously, several alkaloids were isolated from its roots and leaves with pharmacological properties in asthma and acute inflammation models. Therefore, the aim of this study was to evaluate the milonine effect on mast cells degranulation in vivo and in vitro. Swiss mice (n = 8) were used in models of paw edema induced by carrageenan, compound 48/80, or histamine. One hour before challenge, the animals were treated with milonine (at different doses) or standard drugs and, at different time points, the edema formation was measured. In addition, other different methods, such as anaphylactic shock reaction and scratching behavior models both induced by compound 48/80, a mast cell degranulator, were used to assess milonine effect histamine release in vivo. Moreover, milonine effect on mast cell degranulation in vitro was also carried out. Firstly, it was observed that milonine significantly decreased the carrageenan edema formation only at the beginning of the reaction (i.e., up to 2 h after challenge). Furthermore, this alkaloid decreased the edema induced by compound 48/80, maintained the paw tissue integrity, without modulating histamine-induced paw edema. In anaphylactic shock reaction, milonine increased the time of animal survival when compared with compound 48/80 group. Milonine also significantly decreased the scratching behavior induced by compound 48/80 with decreasing of mast cell degranulation in vitro. Therefore, these data indicated that milonine presents anti-allergic properties by decreasing mast cell degranulation rather than acting on histamine effect.

Effects of Glycyrrhizin on the Differentiation of Myeloid Cells of the Heart and Lungs in Lipopolysaccharide-Induced Septic Mice

BACKGROUND

This study investigated the effects of glycyrrhizin (GR) on the ratio of myeloid-derived suppressor cells (MDSCs) to cluster of differentiation (CD)11b+Gr1 myeloid cells in the heart and lungs in lipopolysaccharide (LPS)-induced septic mice.

METHODS

Mice were divided into three groups: Control, LPS, and LPS+GR. After intraperitoneal injection of phosphate-buffered saline for the Control group, LPS for the LPS group, and a combination of LPS and GR for the LPS+GR group, fluorescence-activated cell sorting was utilized to evaluate cytokines and immune cells in the blood, heart, and lungs. Histopathologic analysis of Toll-like receptor (TLR)4 was also performed.

RESULTS

The cytokine amounts in the LPS and LPS+GR groups were significantly higher than in the Control group; however, that in the LPS+GR group was significant lower than in the LPS group. The ratio of MDSCs to CD11b+Gr1 myeloid cells in the LPS+GR group was significantly higher than in the LPS group but was significantly lower than in the Control group. The staining intensity of TLR4 showed the same pattern as that of cytokines in the heart and lungs. TLR4 staining was significantly lower in the LPS+GR group than in the LPS group but was higher than that in the Control group.

CONCLUSION

GR exhibited protective effects on the heart and lungs in LPS-induced septic mice. The effects were associated with an elevated ratio of MDSCs to CD11b+Gr1 myeloid cells and the inhibition of cytokine release and TLR4 expression after GR injection.

Gut-lung axis: The microbial contributions and clinical implications

Gut microbiota interacts with host immune system in ways that influence the development of disease. Advances in respiratory immune system also broaden our knowledge of the interaction between host and microbiome in the lung. Increasing evidence indicated the intimate relationship between the gastrointestinal tract and respiratory tract. Exacerbations of chronic gut and lung disease have been shown to share key conceptual features with the disorder and dysregulation of the microbial ecosystem. In this review, we discuss the impact of gut and lung microbiota on disease exacerbation and progression, and the recent understanding of the immunological link between the gut and the lung, the gut-lung axis.

Thromboxane A2 exacerbates acute lung injury via promoting edema formation

Thromboxane A₂ (TXA₂) is produced in the lungs of patients suffering from acute lung injury (ALI). We assessed its contribution in disease progression using three different ALI mouse models. The administration of hydrochloric acid (HCl) or oleic acid (OA)+ lipopolysaccharide (LPS) caused tissue edema and neutrophil infiltration with TXA₂ production in the lungs of the experimental mice. The administration of LPS induced only neutrophil accumulation without TXA₂ production. Pretreatment with T prostanoid receptor (TP) antagonist attenuated the tissue edema but not neutrophil infiltration in these models. Intravital imaging and immunostaining demonstrated that administration of TP agonist caused vascular hyper-permeability by disrupting the endothelial barrier formation in the mouse ear. In vitro experiments showed that TP-stimulation disrupted the endothelial adherens junction, and it was inhibited by Ca²⁺ channel blockade or Rho kinase inhibition. Thus endogenous TXA₂ exacerbates ALI, and its blockade attenuates it by modulating the extent of lung edema. This can be explained by the endothelial hyper-permeability caused by the activation of TXA₂-TP axis, via Ca²⁺- and Rho kinase-dependent signaling.

Bufexamac ameliorates LPS-induced acute lung injury in mice by targeting LTA4H

Neutrophils play an important role in the occurrence and development of acute lung injury (ALI). Leukotriene B4 (LTB4), a hydrolysis product of epoxide leukotriene A4 (LTA4) catalyzed by LTA4 hydrolase (LTA4H), is one of the most potent chemoattractants for neutrophil. Bufexamac is a drug widely used as an anti-inflammatory agent on the skin, however, the mechanism of action is still not fully understood. In this study, we found bufexamac was capable of specifically inhibiting LTA4H enzymatic activity and revealed the mode of interaction of bufexamac and LTA4H using X-ray crystallography. Moreover, bufexamac significantly prevented the production of LTB4 in neutrophil and inhibited the fMLP-induced neutrophil migration through inhibition of LTA4H. Finally, bufexamac significantly attenuated lung inflammation as reflected by reduced LTB4 levels and weakened neutrophil infiltration in bronchoalveolar lavage fluid from a lipopolysaccharide-induced ALI mouse model. In summary, our study indicates that bufexamac acts as an inhibitor of LTB4 biosynthesis and may have potential clinical applications for the treatment of ALI.

A modified "double-hit" induced acute lung injury model in rats and protective effects of tetramethylpyrazine on the injury via Rho/ROCK pathway

We focused on the production and evaluation of a modified "double-hit" induced acute lung injury (ALI) model, which closely mimics the clinical situation. Further, tetramethylpyrazine (TMP), an alkaloid contained in ligustrazine was evaluated for its potent anti-inflammatory effects in this model. Rats were randomized into 4 groups: G1 (NS control group), G2 ("double-hit" group), G3 (low dosage TMP group) and G4 (high dosage TMP group). The rats in G2, G3 and G4 were intraperitoneally injected with a low dose of LPS followed by intratracheal injection with median dose of LPS to establish the "double-hit" model. The rats in G3, G4 were intraperitoneally injected with low (G3), high (G4) dosage TMP for the protection against ALI. Upon termination of the experiment, TMP attenuated the harmful changes in animal model reaction, breathing frequency, histological examination, lung W/D-weight ratio, BAL fluid PMNs percentage, MPO activity and ROCK2 mRNA expression. We found inhibiting RhoA/ROCK pathway might attribute to TMP-induced protection against ALI.