Restoration of lung surfactant protein D by IL-6 protects against secondary pneumonia following hemorrhagic shock

The Reaction Pathway of miR-30c-5p Activates Lipopolysaccharide Promoting the Course of Traumatic and Hemorrhagic Shock Acute Lung Injury

Acute lung injury (ALI) is an acute hypoxic respiratory failure caused by diffuse inflammatory injury in alveolar epithelial cells during severe infection, trauma, and shock. Among them, trauma/hemorrhagic shock (T/HS) is the main type of indirect lung injury. Despite a great number of clinical studies, indirect factor trauma/hemorrhagic shock to the function and the mechanism in acute lung injury is not clear yet. Therefore, it is still necessary to carry on relevant analysis in order to thoroughly explore its molecular and cellular mechanisms and the pathway of disease function. In our research, we aimed to identify potential pathogenic genes and do modular analysis by downloading disease-related gene expression profile data. And our dataset is from the NCBI-GEO database. Then, we used the Clusterprofiler R package, GO function, and KEGG pathway enrichment analysis to analyze the core module genes. In addition, we also identified key transcription factors and noncoding RNAs. Based on the high degree of interaction of potential pathogenic genes and their involved functions and pathways, we identified 17 dysfunction modules. Among them, up to 9 modules significantly regulate the response to bacterial-derived molecules, and the response to lipopolysaccharide and other related functional pathways that mediate disease development. In addition, miR-290, miR-30c-5p, miR-195-5p, and miR-1-3p-based ncRNA and Jun, Atf1, and Atf3-based transcription factors have a total of 80 transcription drivers for functional modules. In summary, this study confirmed that miR-30c-5p activates lipopolysaccharide response pathway to promote the pathogenesis of ALI induced by hemorrhagic shock. This result can be an important direction for further research on related deepening diseases such as acute respiratory distress syndrome (ARDS). It further provides a piece of scientific medical evidence for revealing the pathogenic principle and cure difficulty of acute lung injury and also provides important guidance for the design of therapeutic strategies and drug development.

Mammals' humoral immune proteins and peptides targeting the bacterial envelope: from natural protection to therapeutic applications against multidrug‐resistant Gram ‐negatives

Mammalian innate immunity employs several humoral ‘weapons’ that target the bacterial envelope. The threats posed by the multidrug‐resistant ‘ESKAPE’ Gram‐negative pathogens (Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) are forcing researchers to explore new therapeutic options, including the use of these immune elements. Here we review bacterial envelope‐targeting (peptidoglycan and/or membrane‐targeting) proteins/peptides of the mammalian immune system that are most likely to have therapeutic applications. Firstly we discuss their general features and protective activity against ESKAPE Gram‐negatives in the host. We then gather, integrate, and discuss recent research on experimental therapeutics harnessing their bactericidal power, based on their exogenous administration and also on the discovery of bacterial and/or host targets that improve the performance of this endogenous immunity, as a novel therapeutic concept. We identify weak points and knowledge gaps in current research in this field and suggest areas for future work to obtain successful envelope‐targeting therapeutic options to tackle the challenge of antimicrobial resistance.

Protective effect of extracorporeal membrane pulmonary oxygenation combined with cardiopulmonary resuscitation on post-resuscitation lung injury

BACKGROUND

Cardiac arrest (CA) is a critical condition that is a concern to healthcare workers. Comparative studies on extracorporeal cardiopulmonary resuscitation (ECPR) and conventional cardiopulmonary resuscitation (CCPR) technologies have shown that ECPR is superior to CCPR. However, there is a lack of studies that compare the protective effects of these two resuscitative methods on organs. Therefore, we aim to perform experiments in swine models of ventricular fibrillation-induced CA to study whether the early application of ECPR has advantages over CCPR in the lung injury and to explore the protective mechanism of ECPR on the post-resuscitation pulmonary injury.

METHODS

Sixteen male swine were randomized to CCPR (CCPR; n=8; CCPR alone) and ECPR (ECPR; n=8; extracorporeal membrane oxygenation with CCPR) groups, with the restoration of spontaneous circulation at 6 hours as an endpoint.

RESULTS

For the two groups, the survival rates between the two groups were not statistically significant (P>0.05), the blood and lung biomarkers were statistically significant (P<0.05), and the extravascular lung water and pulmonary vascular permeability index were statistically significant (P<0.01). Compared with the ECPR group, electron microscopy revealed mostly vacuolated intracellular alveolar type II lamellar bodies and a fuzzy lamellar structure with widening and blurring of the blood-gas barrier in the CCPR group.

CONCLUSIONS

ECPR may have pulmonary protective effects, possibly related to the regulation of alveolar surface-active proteins and mitigated oxidative stress response post-resuscitation.

Targeting Janus Kinases and Signal Transducer and Activator of Transcription 3 to Treat Inflammation, Fibrosis, and Cancer: Rationale, Progress, and Caution

Before it was molecularly cloned in 1994, acute-phase response factor or signal transducer and activator of transcription (STAT)3 was the focus of intense research into understanding the mammalian response to injury, particularly the acute-phase response. Although known to be essential for liver production of acute-phase reactant proteins, many of which augment innate immune responses, molecular cloning of acute-phase response factor or STAT3 and the research this enabled helped establish the central function of Janus kinase (JAK) family members in cytokine signaling and identified a multitude of cytokines and peptide hormones, beyond interleukin-6 and its family members, that activate JAKs and STAT3, as well as numerous new programs that their activation drives. Many, like the acute-phase response, are adaptive, whereas several are maladaptive and lead to chronic inflammation and adverse consequences, such as cachexia, fibrosis, organ dysfunction, and cancer. Molecular cloning of STAT3 also enabled the identification of other noncanonical roles for STAT3 in normal physiology, including its contribution to the function of the electron transport chain and oxidative phosphorylation, its basal and stress-related adaptive functions in mitochondria, its function as a scaffold in inflammation-enhanced platelet activation, and its contributions to endothelial permeability and calcium efflux from endoplasmic reticulum. In this review, we will summarize the molecular and cellular biology of JAK/STAT3 signaling and its functions under basal and stress conditions, which are adaptive, and then review maladaptive JAK/STAT3 signaling in animals and humans that lead to disease, as well as recent attempts to modulate them to treat these diseases. In addition, we will discuss how consideration of the noncanonical and stress-related functions of STAT3 cannot be ignored in efforts to target the canonical functions of STAT3, if the goal is to develop drugs that are not only effective but safe. SIGNIFICANCE STATEMENT: Key biological functions of Janus kinase (JAK)/signal transducer and activator of transcription (STAT)3 signaling can be delineated into two broad categories: those essential for normal cell and organ development and those activated in response to stress that are adaptive. Persistent or dysregulated JAK/STAT3 signaling, however, is maladaptive and contributes to many diseases, including diseases characterized by chronic inflammation and fibrosis, and cancer. A comprehensive understanding of JAK/STAT3 signaling in normal development, and in adaptive and maladaptive responses to stress, is essential for the continued development of safe and effective therapies that target this signaling pathway.

Surfactant Protein D in Respiratory and Non-Respiratory Diseases

Surfactant protein D (SP-D) is a multimeric collectin that is involved in innate immune defense and expressed in pulmonary, as well as non-pulmonary, epithelia. SP-D exerts antimicrobial effects and dampens inflammation through direct microbial interactions and modulation of host cell responses via a series of cellular receptors. However, low protein concentrations, genetic variation, biochemical modification, and proteolytic breakdown can induce decomposition of multimeric SP-D into low-molecular weight forms, which may induce pro-inflammatory SP-D signaling. Multimeric SP-D can decompose into trimeric SP-D, and this process, and total SP-D levels, are partly determined by variation within the SP-D gene, SFTPD. SP-D has been implicated in the development of respiratory diseases including respiratory distress syndrome, bronchopulmonary dysplasia, allergic asthma, and chronic obstructive pulmonary disease. Disease-induced breakdown or modifications of SP-D facilitate its systemic leakage from the lung, and circulatory SP-D is a promising biomarker for lung injury. Moreover, studies in preclinical animal models have demonstrated that local pulmonary treatment with recombinant SP-D is beneficial in these diseases. In recent years, SP-D has been shown to exert antimicrobial and anti-inflammatory effects in various non-pulmonary organs and to have effects on lipid metabolism and pro-inflammatory effects in vessel walls, which enhance the risk of atherosclerosis. A common SFTPD polymorphism is associated with atherosclerosis and diabetes, and SP-D has been associated with metabolic disorders because of its effects in the endothelium and adipocytes and its obesity-dampening properties. This review summarizes and discusses the reported genetic associations of SP-D with disease and the clinical utility of circulating SP-D for respiratory disease prognosis. Moreover, basic research on the mechanistic links between SP-D and respiratory, cardiovascular, and metabolic diseases is summarized. Perspectives on the development of SP-D therapy are addressed.

Low-dose AgNPs reduce lung mechanical function and innate immune defense in the absence of cellular toxicity

Multiple studies have examined the direct cellular toxicity of silver nanoparticles (AgNPs). However, the lung is a complex biological system with multiple cell types and a lipid-rich surface fluid; therefore, organ level responses may not depend on direct cellular toxicity. We hypothesized that interaction with the lung lining is a critical determinant of organ level responses. Here, we have examined the effects of low dose intratracheal instillation of AgNPs (0.05 μg/g body weight) 20 and 110 nm diameter in size, and functionalized with citrate or polyvinylpyrrolidone. Both size and functionalization were significant factors in particle aggregation and lipid interaction in vitro. One day post-intratracheal instillation lung function was assessed, and bronchoalveolar lavage (BAL) and lung tissue collected. There were no signs of overt inflammation. There was no change in surfactant protein-B content in the BAL but there was loss of surfactant protein-D with polyvinylpyrrolidone (PVP)-stabilized particles. Mechanical impedance data demonstrated a significant increase in pulmonary elastance as compared to control, greatest with 110 nm PVP-stabilized particles. Seven days post-instillation of PVP-stabilized particles increased BAL cell counts, and reduced lung function was observed. These changes resolved by 21 days. Hence, AgNP-mediated alterations in the lung lining and mechanical function resolve by 21 days. Larger particles and PVP stabilization produce the largest disruptions. These studies demonstrate that low dose AgNPs elicit deficits in both mechanical and innate immune defense function, suggesting that organ level toxicity should be considered.

Deficiency of the two-pore-domain potassium channel TREK-1 promotes hyperoxia-induced lung injury

OBJECTIVES

We previously reported the expression of the two-pore-domain K channel TREK-1 in lung epithelial cells and proposed a role for this channel in the regulation of alveolar epithelial cytokine secretion. In this study, we focused on investigating the role of TREK-1 in vivo in the development of hyperoxia-induced lung injury.

DESIGN

Laboratory animal experiments.

SETTING

University research laboratory.

SUBJECTS

Wild-type and TREK-1-deficient mice.

INTERVENTIONS

Mice were anesthetized and exposed to 1) room air, no mechanical ventilation, 2) 95% hyperoxia for 24 hours, and 3) 95% hyperoxia for 24 hours followed by mechanical ventilation for 4 hours.

MEASUREMENTS AND MAIN RESULTS

Hyperoxia exposure accentuated lung injury in TREK-1-deficient mice but not controls, resulting in increase in lung injury scores, bronchoalveolar lavage fluid cell numbers, and cellular apoptosis and a decrease in quasi-static lung compliance. Exposure to a combination of hyperoxia and injurious mechanical ventilation resulted in further morphological lung damage and increased lung injury scores and bronchoalveolar lavage fluid cell numbers in control but not TREK-1-deficient mice. At baseline and after hyperoxia exposure, bronchoalveolar lavage cytokine levels were unchanged in TREK-1-deficient mice compared with controls. Exposure to hyperoxia and mechanical ventilation resulted in an increase in bronchoalveolar lavage interleukin-6, monocyte chemotactic protein-1, and tumor necrosis factor-α levels in both mouse types, but the increase in interleukin-6 and monocyte chemotactic protein-1 levels was less prominent in TREK-1-deficient mice than in controls. Lung tissue macrophage inflammatory protein-2, keratinocyte-derived cytokine, and interleukin-1β gene expression was not altered by hyperoxia in TREK-1-deficient mice compared with controls. Furthermore, we show for the first time TREK-1 expression on alveolar macrophages and unimpaired tumor necrosis factor-α secretion from TREK-1-deficient macrophages.

CONCLUSIONS

TREK-1 deficiency resulted in increased sensitivity of lungs to hyperoxia, but this effect is less prominent if overwhelming injury is induced by the combination of hyperoxia and injurious mechanical ventilation. TREK-1 may constitute a new potential target for the development of novel treatment strategies against hyperoxia-induced lung injury.