MiR-24 inhibits inflammatory responses in LPS-induced acute lung injury of neonatal rats through targeting NLRP3

Gender and sex hormone effects on neonatal innate immune function

OBJECTIVES

Scientific evidence provides a widened view of differences in immune response between male and female neonates. The X-chromosome codes for several genes important in the innate immune response and neonatal innate immune cells express receptors for, and are inhibited by, maternal sex hormones. We hypothesized that sex differences in innate immune responses may be present in the neonatal population which may contribute to the increased susceptibility of premature males to sepsis. We aimed to examine the in vitro effect of pro-inflammatory stimuli and hormones in neutrophils and monocytes of male and female neonates, to examine the expression of X-linked genes involved in innate immunity and the miRNA profiles in these populations.

METHODS

Preterm infants (n = 21) and term control (n = 19) infants were recruited from the Coombe Women and Infants University Hospital Dublin with ethical approval and explicit consent. The preterm neonates (eight female, 13 male) were recruited with a mean gestation at birth (mean ± SD) of 28 ± 2 weeks and corrected gestation at the time of sampling was 30 + 2.6 weeks. The mean birth weight of preterm neonates was 1084 ± 246 g. Peripheral blood samples were used to analyze immune cell phenotypes, miRNA human panel, and RNA profiles for inflammasome and inflammatory genes.

RESULTS

Dividing neutrophil results by sex showed no differences in baseline CD11b between sexes among either term or preterm neonates. Examining monocyte CD11b by sex shows, that at baseline, total and classical monocytes have higher CD11b in preterm females than preterm males. Neutrophil TLR2 did not differ between sexes at baseline or following lipopolysaccharide (LPS) exposure. CD11b expression was higher in preterm male non-classical monocytes following Pam3CSK treatment when compared to females, a finding which is unique to our study. Preterm neonates had higher TLR2 expression at baseline in total monocytes, classical monocytes and non-classical monocytes than term. A sex difference was evident between preterm females and term females in TLR2 expression only. Hormone treatment showed no sex differences and there was no detectable difference between males and females in X-linked gene expression. Two miRNAs, miR-212-3p and miR-218-2-3p had significantly higher expression in preterm female than preterm male neonates.

CONCLUSIONS

This study examined immune cell phenotypes and x-linked gene expression in preterm neonates and stratified according to gender. Our findings suggest that the responses of females mature with advancing gestation, whereas male term and preterm neonates have very similar responses. Female preterm neonates have improved monocyte activation than males, which likely reflects improved innate immune function as reflected clinically by their lower risk of sepsis. Dividing results by sex showed changes in preterm and term infants at baseline and following LPS stimulation, a difference which is reflected clinically by infection susceptibility. The sex difference noted is novel and may be limited to the preterm or early neonatal population as TLR2 expression on monocytes of older children does not differ between males and females. The differences shown in female and male innate immune cells likely reflect a superior innate immune defense system in females with sex differences in immune cell maturation. Existing human studies on sex differences in miRNA expression do not include preterm patients, and most frequently use either adult blood or cord blood. Our findings suggest that miRNA profiles are similar in neonates of opposite sexes at term but require further investigation in the preterm population. Our findings, while novel, provide only very limited insights into sex differences in infection susceptibility in the preterm population leaving many areas that require further study. These represent important areas for ongoing clinical and laboratory study and our findings represent an important contribution to exiting literature.

Hypermethylation of microRNA-497-3p contributes to progression of thyroid cancer through activation of PAK1/β-catenin

MicroRNA-497 (miR-497) has been reported to be a tumor-suppressive miRNA in thyroid cancer (TC), yet the mechanism is not clearly defined. In this study, we aim to determine the mechanism by which miR-497-3p affects the progression of TC. After characterization of low miR-497-3p expression pattern in TC and normal tissues, we assessed the correlation between miR-497-3p expression and clinicopathological features of TC patients. Its low expression shared associations with advanced tumor stage and lymph node metastasis. ChIP and methylation-specific PCR provided data showing that downregulation of miR-497-3p in TC tissues was induced by DNA methyltransferase-mediated hypermethylation. By performing dual-luciferase reporter assay, we identified that miR-497-3p targeted PAK1 while PAK1 could inhibit β-catenin expression. Through this mechanism, miR-497-3p exerted the anti-proliferative, anti-invasive, pro-apoptotic, and anti-tumorigenic effects on TC cells on the strength of the results from gain-of-function and rescue experiments. This study suggested that hypermethylation of miR-497-3p resulted in upregulation of β-catenin dependent on PAK1 and contributed to cancer progression in TC, which highlighted one of miR-mediated tumorigenic mechanism.

Changes and Clinical Value of Serum miR-24 and miR-223 Levels in Patients with Severe Pneumonia

Introduction

Severe pneumonia progresses rapidly, so early assessment of the severity and prognosis is crucial for reducing mortality rates.

Objective

We explore the role of serum microRNA-24 (miR-24) and microRNA-223 (miR-223) in the prognosis of severe pneumonia.

Methods

There were a total of 96 patients with general pneumonia, 94 patients with severe pneumonia, and 93 healthy people, who were enrolled in this study. The levels of serum miR-24 and miR-223 were detected by real-time fluorescent quantitative PCR in all groups.

Results

The serum miR-223 level in the severe group was higher than that in the common group and the control group, and the miR-24 level was lower than that in the common group and the control group (P<0.05). The serum miR-223 levels and APACHEII scores in the death group were higher than those in the survival group on the first, third, and seventh day after admission, while the miR-24 levels were lower than those in the survival group (P<0.05). The proportion of patients with mechanical ventilation in the death group was higher than that in the survival group (P<0.05). The level of serum miR-24 was negatively correlated with APACHEII score and mechanical ventilation in patients who died of severe pneumonia (P<0.05), and miR-223 was positively correlated with APACHEII score and mechanical ventilation (P<0.05). The AUC predicted by serum miR-24, miR-223, and APACHEII scores alone and jointly were 0.867, 0.839, 0.791, and 0.952, respectively. MiR-24 and miR-223 are protective and independent risk factors for mortality in severe pneumonia patients, respectively (P<0.05). MiR-24 was a protective factor affecting the death of patients with severe pneumonia, and miR-223 was an independent risk factor affecting the death of patients with severe pneumonia (P<0.05).

Conclusion

The combination of serum miR-24 and miR-223 levels on the first day after admission and APACHEII score can effectively predict prognosis.

Endoplasmic Reticulum Stress in Elderly Patients with COVID-19: Potential of Melatonin Treatment

Aging processes, including immunosenescence, inflammation, inflammasome formation, genomic instability, telomeric attrition, and altered autophagy, are involved in viral infections and they may contribute to increased pathophysiological responses to the SARS-CoV-2 infection in the elderly; this poses additional risks of accelerated aging, which could be found even after recovery. Aging is associated with oxidative damage. Moreover, SARS-CoV-2 infections may increase the production of reactive oxygen species and such infections will disturb the Ca++ balance via an endoplasmic reticulum (ER) stress-mediated unfolded protein response. Although vaccine development and anti-inflammation therapy lower the severity of COVID-19, the prevalence and mortality rates are still alarming in some countries worldwide. In this review, we describe the involvement of viral proteins in activating ER stress transducers and their downstream signals and in inducing inflammation and inflammasome formation. Furthermore, we propose the potential of melatonin as an ER stress modulator, owing to its antioxidant, anti-inflammatory, and immunoregulatory effects in viral infections. Considering its strong safety profile, we suggest that additive melatonin supplementation in the elderly could be beneficial in treating COVID-19.

Cannabidiol (CBD) Protects Adipose-Derived Mesenchymal Stem Cells (ASCs) against Endoplasmic Reticulum Stress Development and Its Complications

BACKGROUND

Recent studies suggested that individuals with metabolic disorders have altered function of adipocytes and adipose stem cell subpopulations, which impairs tissue homeostasis, promoting insulin resistance and diabetes development. The non-psychoactive phytocannabinoid CBD was found to modulate adipose tissue metabolism, however, its exact role in controlling ASCs' fate is still poorly understood.

OBJECTIVES

This investigation aimed to elucidate whether pretreatment of ASCs with CBD can protect against ER stress development and maintain the cytophysiological properties of cells.

METHODS

Human ASCs were cultured under control and adipogenic conditions. Prior to the experiments, cells in the experimental group were pretreated with CBD following the addition of an ER stress inducer-tunicamycin. After the experiments, the cells were subsequently tested for expression of the apoptotic, ER stress, and anti-inflammatory-related genes using RT-qPCR. Oxidative stress was analysed with flow cytometric assays.

RESULTS

Cells pretreated with CBD displayed decreased apoptosis and enhanced proliferation rate. Additionally, the expression of pro-inflammatory cytokines and miRNAs was significantly reduced. The obtained results also demonstrated an obvious reduction in intracellular accumulated ROS and NO, as well as mitigated ER stress through the down-regulation of IRE-1, PERK, CHOP, and ATF6 transcripts upon CBD treatment.

CONCLUSION

The presented data provide the evidence that CBD protects ASCs against ER stress development and its complications and, thus, offers new insights for the management of obesity through the regulation of adipose tissue dynamics.

Pellino2 accelerate inflammation and pyroptosis via the ubiquitination and activation of NLRP3 inflammation in model of pediatric pneumonia

BACKGROUND

Mycoplasma pneumoniae pneumonia (MPP) is a common and frequently-occurring disease in pediatrics. This study aims to via unveiling the novel effects and mechanisms of Pellino2 in model of pediatric pneumonia.

MATERIALS AND METHODS

Male infancy C57BL/6 mice were injected with 2 mg/kg of LPS (Sigma-Aldrich Merck KGaA). THP-1 cells were induced with LPS and ATP.

RESULTS

The expression of Pellino2 mRNA and protein in patients with pediatric pneumonia or mice with pediatric pneumonia were reduced. Pellino2 accelerated lung injury and expanded inflammation and pyroptosis in lung tissue of pediatric pneumonia in vivo and vitro model. Furthermore, the inhibition of Pellino2 reduced lung injury and weakened inflammation and pyroptosis in lung tissue of pediatric pneumonia in vivo and vitro model. Pellino2 protein catenated NLRP3 protein, and Pellino2 promoted ubiquitination and activation of NLRP3 inflammation in model of pediatric pneumonia. Pellino2 accelerate inflammation and pyroptosis in model of pediatric pneumonia by NLRP3.

CONCLUSIONS

These results suggest that Pellino2 accelerate inflammation and pyroptosis via the induction of ubiquitination and activation of NLRP3 inflammation in model of pediatric pneumonia, Pellino2 may serve as a potential approach for the treatment of pediatric pneumonia and other inflammatory diseases.

Integrated Pharmacology Reveals the Molecular Mechanism of Gegen Qinlian Decoction Against Lipopolysaccharide-induced Acute Lung Injury

ALI is a severe inflammatory disease of the lungs. In previous studies, we found that GQD was effective against ALI, but specific molecular mechanism is still unclear. Therefore, this study was to examine effect of GQD on LPS-induced ALI rats and underlying mechanisms using multi-omics and molecular methods. The results showed that GQD significantly improved lung tissue damage, reduced pulmonary edema, inhibited MPO activity, and improved respiratory function in ALI rat. Additionally, GQD significantly reduced the levels of TNF-α, IL-1β, and IL-6 in serum and BALF. Furthermore, metabolomic analysis showed that GQD reduced pulmonary inflammation by improving metabolic remodeling. Moreover, transcriptomic analysis showed that GQD inhibited the activation of complement pathway and regulated Th17 and Treg cells balance. Additionally, GQD inhibited the expression of C3, C5a, and IL-17, and promoted the expression of TGF-β and CYP1A1 at the mRNA and protein levels. Gut microbial assay showed that GQD treatment increased the relative abundance of Firmicutes and their genera in intestinal microbiota, and increased short-chain fatty acids concentration. Overall, GQD treated ALI by improving metabolic remodeling, affecting immune-related pathways and regulating intestinal microbiota. This study provides a solid scientific basis for promoting the clinical use of GQD in treating ALI.

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.

Circ_0026579 alleviates LPS-induced WI-38 cells inflammation injury in infantile pneumonia

Circular RNA (circRNA) represents an important regulator in infantile pneumonia progression. To clarify the role of circ_0026579 in this disease, LPS was used to treat WI-38 cells to mimic inflammation injury. The levels of inflammatory factors were determined by ELISA assay. Cell proliferation and apoptosis were measured by MTT assay, EdU staining and flow cytometry. The protein levels of cyclinD1, cleaved-caspase-3 and insulin-like growth factor 2 (IGF2) were examined using Western blot analysis. Cell oxidative stress was assessed by detecting MDA level and SOD activity. The expression of circ_0026579, miR-24-3p and IGF2 were analyzed using quantitative real-time PCR, and the interaction between miR-24-3p and circ_0026579 or IGF2 was confirmed by dual-luciferase reporter assay and RIP assay. LPS induced inflammation in WI-38 cells. Circ_0026579 expression was promoted in LPS-induced WI-38 cells, and its knockdown alleviated LPS-induced WI-38 cells inflammation. MiR-24-3p was sponged by circ_0026579, and its expression was reduced by LPS. MiR-24-3p inhibitor reversed the regulation of circ_0026579 knockdown on LPS-induced WI-38 cells inflammation. IGF2 was targeted by miR-24-3p, and its expression could be enhanced by LPS. MiR-24-3p relieved the inflammation of WI-38 cells which could be abolished by IGF2 overexpression. Circ_0026579 positively regulated IGF2 expression through sponging miR-24-3p. Circ_0026579 knockdown alleviated LPS-induced WI-38 cells inflammation by miR-24-3p/IGF2 axis, suggesting that circ_0026579 might contribute to infantile pneumonia progression.

MicroRNA miR-24-3p Mediates the Negative Regulation of Lipopolysaccharide-Induced Endometrial Inflammatory Response by Targeting TNF Receptor-Associated Factor 6 (TRAF6)

Purpose

Endometritis is a female reproductive disease that affects the cattle industries development and microRNAs (miRNAs) play a pivotal role and critical regulators of the innate immune response in varieties of diseases. The present study intends to investigate the regulatory role of miR‐24-3p in the innate immune response involved in endometritis and evaluate its therapeutic potential.

Methods

Whole mice uteri and bovine endometrial epithelial cells (BEECs) were separately stimulated with LPS. The BEECs were also transfected with miR-24-3p mimic and negative control; siTRAF6 and siNC; pcDNA3.1 empty and pcDNA3.1(+)TRAF6 separately with LPS stimulation. The expression levels of miR‐24-3p and TRAF6 were measured via quantitative real‐time polymerase chain reaction (qRT-PCR) and Western blot, respectively. LPS‐induced inflammatory response assessed by inflammatory cytokines secretion and expression via ELISA and qRT-PCR. Bioinformatics analysis and luciferase reporter assay validated the interaction between miR‐24-3p and TRAF6. The activation of the NF‐ĸB/MAPK pathway and p65 phosphorylation was investigated by Western blot and immunofluorescence assay, respectively.

Results

The expression of miR‐24-3p was decreased, and TRAF6 was elevated with an increased level of pro-inflammatory cytokines in LPS‐treated BEECs and mice uterus. The overexpression of miR‐24-3p suppressed LPS‐induced secretion of inflammatory cytokines (IL‐1β, IL‐6, IL-8 and TNF-α) and deactivation of NF‐ĸB/MAPK pathways. The downregulation of TRAF6 inhibited LPS‐induced inflammatory response in BEECs. TRAF6 is validated as a target of miR‐24-3p, and miR‐24-3p reversed the overexpression of cloned TRAF6 on inflammation response in BEECs.

Conclusion

Our findings demonstrate that the overexpression of miR‐24-3p attenuates endometrial inflammation and the expression of pro-inflammatory mediators via suppressing TRAF6. Therefore, modulating the pathogenesis of endometritis and possibly, a therapeutic potential against endometritis.

Antipharyngitis Effects of Syringa oblata L. Ethanolic Extract in Acute Pharyngitis Rat Model and Anti-Inflammatory Effect of Ir-Idoids in LPS-Induced RAW 264.7 Cells

Acute pharyngitis is an inflammation of the pharyngeal mucous membrane and submucous lymphoid tissues. Unsatisfactory treatment and repeated occurrences might cause chronic pharyngitis and other complications. Syringa oblata L. (S. oblata) is a traditional Chinese medicine that exhibited a significant therapeutic effect on various inflammatory diseases. Its commercial drug Yan Li Xiao (YLX) capsule is used as a cure for the treatment of inflammatory diseases, such as bacillary dysentery, tonsillitis, bronchitis, and acute gastroenteritis. However, studies about S. oblata relieving acute pharyngitis are rare. In this study, high-performance liquid chromatography (HPLC) was used to analyze the chemical profile of S. oblata, and the bioactive phytoconstituents were isolated and identified by nuclear magnetic resonance (NMR) and mass spectrometry. An ammonia-induced acute pharyngitis rat model was established to estimate the protective effect of S. oblata in vivo for the first time. The severity of pharyngitis was observed by appearance index and HE staining. The cytokines expression was performed by ELISA. Crucial proteins expression associated with TLR4/NF-κB/MAPK and NLRP3 inflammasome signaling pathways were analyzed by western blotting and immunohistochemistry. Furthermore, the anti-inflammatory effect of isolated compounds was evaluated by suppressing lipopolysaccharide- (LPS-) induced NO generation and regulating the cytokines levels in RAW 264.7 cells. The results showed that S. oblata exhibited a protective effect in the ammonia-induced acute pharyngitis rat model, and the compounds exert potential anti-inflammatory properties against LPS-activated RAW 254.7 cells.

Cardioprotection of M2 macrophages-derived exosomal microRNA-24-3p/Tnfsf10 axis against myocardial injury after sepsis

OBJECTIVE

Some reports have suggested the involvement of microRNA-24-3p (miR-24-3p) in heart diseases. Here, the intention of this work was to unmask whether miR-24-3p from M2 macrophages-derived exosomes (M2-exo) could protect against myocardial injury after sepsis.

METHODS

Mice model of sepsis was induced by intraperitoneal injection of lipopolysaccharide (LPS). miR-24-3p and tumor necrosis factor superfamily member 10 (Tnfsf10) expression levels were measured in the myocardial tissue of septic mice. M2-exo were isolated, in which miR-24-3p expression was altered. Then, septic mice were alone or in combination injected with the miR-24-3p-modified M2-exo or siRNA of Tnfsf10. Subsequently, cardiac function, apoptosis and serum inflammatory response were examined.

RESULTS

miR-24-3p expression dropped while Tnfsf10 expression raised in the myocardial tissue of septic mice. M2-exo-derived miR-24-3p or deficiency of Tnfsf10 had cardioprotective effects on LPS-induced myocardial injury in mice through improving cardiac function and reducing cardiomyocyte apoptosis in the myocardial tissue and serum inflammation. A binding relation exhibited between miR-24-3p and Tnfsf10, and M2-exo-derived miR-24-3p alleviated LPS-induced myocardial injury by inhibiting Tnfsf10.

CONCLUSION

Up-regulating miR-24-3p from M2-exo imposes cardioprotection against myocardial injury after sepsis through reducing Tnfsf10 expression.

MicroRNA Bta-miR-24-3p Suppressed Galectin-9 Expression through TLR4/NF-ĸB Signaling Pathway in LPS-Stimulated Bovine Endometrial Epithelial Cells

Endometritis is a major infectious disease affecting dairy development. MicroRNAs are recognized as critical regulators of the innate immune response. However, the role and mechanism of Bta-miR-24-3p in the development of endometritis are still unclear. This study aimed to investigate the effect of Bta-miR-24-3p on the inflammatory response triggered by lipopolysaccharide (LPS) and to clarify the possible mechanism. LPS-treated bovine endometrial epithelial cells (BEECs) were cultured to investigate the role of Bta-miR-24-3p. The expression levels of Bta-miR-24-3p were downregulated, and galectin-9 (LGALS9) were measured by quantitative real-time polymerase chain reaction. The LPS-induced inflammatory response was assessed by the elevated secretion of inflammatory cytokines measured by using enzyme-linked immunosorbent assay and quantitative real-time polymerase chain reaction. Activation of nuclear factor-κB (NF-κB) and TLR4 pathway was assessed by Western blot. The interaction between Bta-miR-24-3p and LGALS9 was validated by bioinformatics analysis and a luciferase reporter assay. LPS-induction in BEECs with Bta-miR-24-3p was overexpressed leads inhibition of pro-inflammatory cytokines, LGALS9 expression, and TLR4/NF-ĸB pathway deactivation. Knockdown of LGALS9 inhibited the LPS-induced inflammatory response in BEECs. LGALS9 was validated as a target of Bta-miR-24-3p. Cloned overexpression of LGALS9 failed to alter the effect of Bta-miR-24-3p on the inflammatory response in BEECs. Overall, Bta-miR-24-3p attenuated the LPS-induced inflammatory response via targeting LGALS9. The immunotherapeutic stabilisation of Bta-miR-24-3p could give a therapeutic option for endometritis and other disorders commonly associated with endometritis, suggesting a novel avenue for endometritis treatment.

DF-1 cells prevent MG-HS infection through gga-miR-24-3p/RAP1B mediated decreased proliferation and increased apoptosis

Mycoplasma gallisepticum (MG) is a major poultry pathogen that can induce Chronic Respiratory Disease (CRD) in chickens, causing serious economic losses in the poultry industry worldwide. Increasing evidence suggests that microRNAs (miRNAs) act as a vital role in resisting microbial pathogenesis and maintaining cellular mechanism. Our previous miRNAs sequencing data showed gga-miR-24-3p expression level was significantly increased in MG-infected chicken lungs. The aim of this study is to reveal the cellular mechanism behind the MG-HS infection. We found that gga-miR-24-3p was significantly upregulated and Ras-related protein-B (RAP1B) was downregulated in chicken fibroblast cells (DF-1) with MG infection. Dual luciferase reporting assay and rescue assay confirmed that RAP1B was the target gene of gga-miR-24-3p. Meanwhile, overexpressed gga-miR-24-3p increased the levels of tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β), and significantly inhibited cell proliferation as well as promoted MG-infected DF-1 cell apoptosis, whereas inhibition of gga-miR-24-3p had the opposite effect. More importantly, the results of overexpression and knockdown of target gene RAP1B demonstrated that the presence of RAP1B promoted cell proliferation and it saved the reduced or increased cell proliferation caused by overexpression or inhibition of gga-miR-24-3p. Furthermore, the overexpression of gga-miR-24-3p could significantly inhibit the expression of MG-HS adhesion protein. Taken together, these findings demonstrate that DF-1 cells can resist MG-HS infection through gga-miR-24-3p/RAP1B mediated decreased proliferation and increased apoptosis, which provides a new mechanism of resistance to MG infection in vitro.

Suppression of lncRNA NLRP3 inhibits NLRP3-triggered inflammatory responses in early acute lung injury

Acute lung injury (ALI) is a common lung pathology that is accompanied by alveolar macrophage (AM) activation and inflammatory response. This study investigated the role of the long non-coding RNA NONRATT004344 (hereafter named lncRNA NLRP3) in regulating the Nod-like receptor protein 3 (NLRP3)-triggered inflammatory response in early ALI and the underlying mechanism as well. We established LPS-induced ALI models to explore their interactive mechanisms in vitro and in vivo. Luciferase reporter assays were performed to determine that miR-138-5p could bind to lncRNA NLRP3 and NLRP3. We observed increased lncRNA NLRP3 expression, decreased miR-138-5p expression, NLRP3 inflammasome activation, and upregulated caspase-1, IL-1β, and IL-18 expression in the LPS-induced ALI model. Furthermore, lncRNA NLRP3 overexpression activated the NLRP3 inflammasome and promoted IL-1β and IL-18 secretion; the miR-138-5p mimic abolished these effects in vivo and in vitro. Consistently, miR-138-5p inhibition reversed the effects of lncRNA NLRP3 silencing on the expression of NLRP3-related molecules and inhibition of the NLRP3/caspase-1/IL-1β signalling pathway. Mechanistically, lncRNA NLRP3 sponging miR-138-5p facilitated NLRP3 activation through a competitive endogenous RNA (ceRNA) mechanism. In summary, our results suggested that lncRNA NLRP3 binding miR-138-5p promotes NLRP3-triggered inflammatory response via lncRNA NLRP3/miR-138-5p/NLRP3 ceRNA network (ceRNET) and provides insights into the treatment of early ALI.

Expression Profiling of microRNA From Peripheral Blood of Dairy Cows in Response to Staphylococcus aureus-Infected Mastitis

As the main pathogen causing dairy cow mastitis, Staphylococcus aureus can cause subclinical mastitis, which is difficult to be diagnosed. It seriously affects milk quality and the economic benefits of the dairy industry. Therefore, it is very necessary to find biomarkers for early diagnosis of S. aureus-infected mastitis in peripheral blood of dairy cows. In this study, S. aureus was used to infect the mammary gland tissues of dairy cows, and a mastitis model was successfully constructed. The RNAseq technology was used to determine the expression profiles of microRNA (miRNA) from peripheral blood of dairy cows infected with S. aureus at 0, 1, 3, 5, and 7 days. A total of 288 differentially expressed miRNAs (DIE-miRNAs) were found, of which 108 were known miRNAs and 180 were novel predicted miRNAs. Bioinformatics analysis results showed that the above DIE-miRNAs might be involved in 10 immune system-related signaling pathways (i.e., chemokine signaling pathway, leukocyte transendothelial migration, natural killer cell-mediated cytotoxicity, toll-like receptor signaling pathway, Jak-STAT signaling pathway, MAPK signaling pathway, Wnt signaling pathway, cell adhesion molecules, cytokine-cytokine receptor interaction, and ECM-receptor interaction), thus regulating the process of S. aureus mastitis. It was also found that the expression variation of up-regulated expression of miR-320a, miR-19a, and miR-19b as well as down-regulated expression of miR-143, miR-205, and miR-24 reached a significant level on the 5th and 7th day of infection, suggesting that they might play an important biological role in mastitis and provide a direction for the research and development of molecular therapy technology for mastitis. However, at different times after S. aureus infection, miR-1301 was significantly up-regulated in peripheral blood. miR-2284r was significantly down-regulated, suggesting that these two miRNAs might be the new blood biomarkers for S. aureus-infected dairy cow mastitis. The above results laid a new foundation for the research and development of molecular diagnosis and biological therapy technology for S. aureus-infected mastitis in dairy cow.

A Blood Exosomal miRNA Signature in Acute Respiratory Distress Syndrome

Acute respiratory distress syndrome (ARDS) is a diffuse, acute, inflammatory lung disease characterized by a severe respiratory failure. Recognizing and promptly treating ARDS is critical to combat the high mortality associated with the disease. Despite a significant progress in the treatment of ARDS, our ability to identify early patients and predict outcomes remains limited. The development of novel biomarkers is crucial. In this study, we profiled microRNA (miRNA) expression of plasma-derived exosomes in ARDS disease by small RNA sequencing. Sequencing of 8 ARDS patients and 10 healthy subjects (HSs) allowed to identify 12 differentially expressed exosomal miRNAs (adjusted p < 0.05). Pathway analysis of their predicted targets revealed enrichment in several biological processes in agreement with ARDS pathophysiology, such as inflammation, immune cell activation, and fibrosis. By quantitative RT-PCR, we validated the alteration of nine exosomal miRNAs in an independent cohort of 15 ARDS patients and 20 HSs, among which seven present high capability in discriminating ARDS patients from HSs (area under the curve > 0.8) (miR-130a-3p, miR-221-3p, miR-24-3p, miR-98-3p, Let-7d-3p, miR-1273a, and miR-193a-5p). These findings highlight exosomal miRNA dysregulation in the plasma of ARDS patients which provide promising diagnostic biomarkers and open new perspectives for the development of therapeutics.

Narciclasine attenuates LPS-induced acute lung injury in neonatal rats through suppressing inflammation and oxidative stress

Acute lung injury (ALI) is a life-threatening disorder related to serious pulmonary inflammation. Narciclasine exhibits strong anti-inflammation activity and attenuates the reactive oxygen species (ROS) production. The present study aims to investigate the underlying mechanism related to the effect of narciclasine on the pathogenesis of neonatal acute lung injury (ALI). Narciclasine attenuated LPS-induced pathological injury and pulmonary edema. In addition, narciclasine suppressed the secretion of inflammatory cytokines, including necrosis factor-α (TNF-α), Interleukin (IL-6), IL-1β, monocyte chemotactic protein-1 (MCP-1) in serum, and inhibited the expressions of intercellular adhesion molecule-1 (ICAM-1) and vascular cell adhesion molecule-1 (VCAM-1) in lung tissues of neonatal ALI rats. Furthermore, narciclasine alleviated oxidative stress and apoptosis in lung tissues. Importantly, narciclasine exerted an inhibition effect on NF-κB nuclear translocation and activation of Toll-like Receptor 4 (TLR4)/Nuclear factor (NF)-κB/Cyclooxygenase 2 (Cox2) signaling pathway. Taken together, narciclasine protected against lung injury via inhibition effect on excessive inflammation, oxidative stress and apoptosis, hence, narciclasine may be considered as an effective and novel agent for clinical therapeutic strategy of ALI Treatment.

MicroRNA-24-3p Inhibits Microglia Inflammation by Regulating MK2 Following Spinal Cord Injury

Spinal cord injury (SCI) is a functional impairment of the spinal cord caused by external forces, accompanied by limb movement disorders and permanent paralysis, which seriously lowers the life quality of SCI patients. Secondary injury caused by inflammation attenuated the therapeutic effects of SCI. Therefore, the exploration of biomarkers associated with the inflammatory response following SCI might provide novel therapy strategy against SCI.SCI rat model was established as previously reported and evaluated by BBB score. The expression of microRNA-24-3p (miR-24-3p) and MAPK-activated protein kinase 2 (MK2) in spinal cord tissues of SCI rats and HAPI cells was analyzed by qRT-PCR. Protein expression of MK2, ionized calcium-binding adapter molecule-1 (Iba-1), tumor necrosis factor-alpha (TNF-α), and interleukin-1β (IL-1β) was assessed by western blot assay. The release of inflammatory cytokines TNF-α and IL-1β was measured by enzyme-linked immunosorbent assay (ELISA). The interaction between miR-24-3p and MK2 was examined by the luciferase reporter system. Basso-Beattie-Bresnahan (BBB) score dramatically reduced in rats following SCI compared with sham rats. Moreover, the expression of miR-24-3p was down-regulated, while MK2 was up-regulated in the spinal cord tissues of SCI rats and LPS-induced microglia cells compared with the corresponding control group. Luciferase reporter system confirmed the interaction between miR-24-3p and MK2. In addition, miR-24-3p upregulation or MK2 knockdown attenuated LPS induced activation of microglial cells and expression of inflammatory cytokine TNF-α and IL-1β. Besides, we discovered that miR-24-3p regulated inflammation of highly aggressively proliferating immortalized (HAPI) cells by targeting MK2.In our study, we clarified that miR-24-3p repressed inflammation of microglia cells following SCI by regulating MK2, thereby providing promising biomarkers for SCI therapy.

Emodin protects against intestinal and lung injury induced by acute intestinal injury by modulating SP-A and TLR4/NF-κB pathway

Objective: Our aim was to investigate the effect of emodin on intestinal and lung injury induced by acute intestinal injury in rats and explore potential molecular mechanisms.

Methods: Healthy male Sprague–Dawley (SD) rats were randomly divided into five groups (n=10, each group): normal group; saline group; acute intestinal injury model group; model + emodin group; model+NF-κB inhibitor pynolidine dithiocarbamate (PDTC) group. Histopathological changes in intestine/lung tissues were observed by Hematoxylin and Eosin (H&E) and terminal deoxynucleotidyl transferase biotin-dUTP nick-end labeling (TUNEL) staining. Serum IKBα, p-IKBα, surfactant protein-A (SP-A) and toll-like receptor 4 (TLR4) levels were examined using enzyme-linked immunosorbent assay (ELISA). RT-qPCR was performed to detect the mRNA expression levels of IKBα, SP-A and TLR4 in intestine/lung tissues. Furthermore, the protein expression levels of IKBα, p-IKBα, SP-A and TLR4 were detected by Western blot.

Results: The pathological injury of intestinal/lung tissues was remarkedly ameliorated in models treated with emodin and PDTC. Furthermore, the intestinal/lung injury scores were significantly decreased after emodin or PDTC treatment. TUNEL results showed that both emodin and PDTC treatment distinctly attenuated the apoptosis of intestine/lung tissues induced by acute intestinal injury. At the mRNA level, emodin significantly increased the expression levels of SP-A and decreased the expression levels of IKBα and TLR4 in intestine/lung tissues. According to ELISA and Western blot, emodin remarkedly inhibited the expression of p-IKBα protein and elevated the expression of SP-A and TLR4 in serum and intestine/lung tissues induced by acute intestinal injury.

Conclusion: Our findings suggested that emodin could protect against intestinal and lung injury induced by acute intestinal injury by modulating SP-A and TLR4/NF-κB pathway.

Chicoric acid alleviates LPS-induced inflammatory response through miR-130a-3p/IGF-1pathway in human lung A549 epithelial cells

To investigate the effects and potential mechanisms of chicoric acid (CA) on LPS-induced inflammatory response in A549 cells. 0–800 μM CA was added to A549 cells to determine the toxicity of CA using MTT assay. Then, 2 μg/mL LPS and 50 μM CA were simultaneously added to A549 cells to investigate the effects of CA. In order to investigate the effects of miR-130a-3p and IGF-1 on LPS-induced A549 cells, cells were infected with inhibitor of miR-130a-3p and si RNA IGF-1. The levels of inflammatory cytokines such as IL-1β, IL-6, and TNF-α were measured by real-time RT-PCR and enzyme-linked immunosorbent (ELISA) assay. The IGF-1 pathway and NF-κB expression were measured using immunoblot assay. Moreover, a luciferase activity assay was used to indicate the binding site of miR-130a-3p on the 3′UTR of IGF-1. 0–50 μM CA had no toxicity on A549 cells. Thus, we chose 50 μM CA for the following study. CA attenuated the inflammatory response by LPS through decreasing IL-1β, IL-6, and TNF-α levels and increasing IGF-1/IGF-1R expression. Inhibition of miR-130a-3p reduced the inflammatory response and restored IGF-1/IGF-1R pathway induced by LPS. Furthermore, luciferase activity results indicated that miR-130a-3p directly targeted IGF-1 to regulate inflammatory response. CA alleviates LPS-induced inflammatory response through miR-130a-3p/IGF-1pathway in A549 cells.

miR-642a-5p partially mediates the effects of lipopolysaccharide on human pulmonary microvascular endothelial cells via eEF2

Inhalation or systemic administration of lipopolysaccharide (LPS) can induce acute pulmonary inflammation and lung injury. The pulmonary vasculature is composed of pulmonary microvascular endothelial cells (PMVECs), which form a semiselective membrane for gas exchange. The miRNA miR‐642a‐5p has previously been reported to be up‐regulated in patients with acute respiratory distress syndrome; thus, here, we examined whether this miRNA is involved in the effects of LPS on PMVECs. The levels of miR‐642a‐5p and mRNA encoding eukaryotic elongation factor 2 (eEF2) were detected by quantitative RT‐PCR. Moesin and eEF2 protein levels were tested by western blot assay. Dual‐luciferase reporter assay was used to examine the relationship between miR‐642a‐5p and eEF2. Cell viability was assessed using the 3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide assay, and cell permeability was analyzed using the transendothelial electrical resistance assay. We report that miR‐642a‐5p levels are significantly up‐regulated in LPS‐stimulated PMVECs, and miR‐642a‐5p contributes to LPS‐induced hyperpermeability and apoptosis of PMVECs. LPS treatment results in down‐regulation of eEF2 in PMVECs. Overexpression of eEF2, a direct target of miR‐642a‐5p, inhibited the effect of LPS on PMVECs. miR‐642a‐5p promoted LPS‐induced hyperpermeability and apoptosis by targeting eEF2. Thus, miR‐642a‐5p and eEF2 may serve as potential targets for acute lung injury/acute respiratory distress syndrome diagnosis or treatment.

Decreased expression of miR-24 in peripheral plasma of type 2 diabetes mellitus patients associated with diabetic foot ulcer

To examine the correlations of miR-24 expression in peripheral plasma with the onset of diabetic foot ulcer (DFU) and diabetic foot osteomyelitis (DFO) in type 2 diabetes mellitus (T2DM) patients and explore the clinical value of miR-24 as a potential biomarker for the diagnosis and treatment outcomes of DFU and DFO, a total of 60 newly diagnosed T2DM patients without DFU (T2DM group), 112 T2DM patients with DFU (DFU group), and 60 healthy controls (NC group) were included. DFU group were further divided into DFO group (n = 64) and non-DFO group (n = 48). MiR-24 levels were determined by quantitative real-time PCR, while clinical features and risk factors of DFU and DFO were explored. The expression level of miR-24 in T2DM and DFU group was significantly lower than in NC group (P < .05), and that in DFU group was significantly lower than in T2DM group (P < .01). Additionally, the level of miR-24 significantly decreased in DFO group compared to non-DFO group (P < .01). Moreover, it was negatively correlated with the amputation rate in DFU group (P = .043) and positively correlated with healing rate after 8 weeks (P = .036). The multivariate logistic regression analysis confirmed that a low expression of miR-24 was an independent risk factor for DFU and DFO. The ROC curve analysis indicated that the AUC of miR-24 for the diagnosis of DFU and DFO was 0.849 (95% CI, 0.618-0.879, P < .001) and 0.782 (95% CI, 0.595-0.813, P < .001). Thus, a decreased expression of miR-24 of T2DM patients was closely related to the occurrence, development and prognosis of DFU and DFO, suggesting the use of miR-24 as a potential biomarker for the prediction of DFU and DFO.

Crosstalk between ER stress, NLRP3 inflammasome, and inflammation

Endoplasmic reticulum stress (ERS) is a protective response to restore protein homeostasis by activating the unfolded protein response (UPR). However, UPR can trigger cell death under severe and/or persistently high ERS. The NLRP3 inflammasome is a complex of multiple proteins that activates the secretion of the proinflammatory cytokine IL-1β in a caspase-1-dependent manner to participate in the regulation of inflammation. The NLRP3 inflammasome involvement in ERS-induced inflammation has not been completely described. The intersection of ERS with multiple inflammatory pathways can initiate and aggravate chronic diseases. Accumulating evidence suggests that ERS-induced activation of NLRP3 inflammasome is the pathological basis of various inflammatory diseases. In this review, we have discussed the networks between ERS and NLRP3 inflammasome, with the view to identifying novel therapeutic targets in inflammatory diseases. KEY POINTS: • Endoplasmic reticulum stress (ERS) is an important factor for the activation of the NLRP3 inflammasomes that results in pathological processes. • ERS can activate the NLRP3 inflammasome to induce inflammatory responses via oxidative stress, calcium homeostasis, and NF-κB activation. • The interactions between ERS and NLRP3 inflammasome are associated with inflammation, which represent a potential therapeutic opportunity of inflammatory diseases.

MicroRNA‑93 contributes to the suppression of lung inflammatory responses in LPS‑induced acute lung injury in mice via the TLR4/MyD88/NF‑κB signaling pathway

Acute lung injury (ALI) is a severe inflammatory lung disease with a rapid onset. The anti-inflammatory functions of microRNA-93 (miRNA/miR-93) have been described in various types of tissue injury and disease. However, the biological role of miR-93 and its molecular mechanisms underlying the initiation and progression of ALI have not yet been reported, at least to the best of our knowledge. The present study aimed to investigate the regulatory effects exerted by miR-93 in ALI. Using an in vivo murine model of ALI induced by lipopolysaccharide (LPS), miR-93 expression was found to be downregulated in the lung tissues and bronchoalveolar lavage fluid (BALF) compared with the control group. Following agomiR-93 injection, it was observed that agomiR-93 attenuated lung injury, as evidenced by decreased lung permeability, a reduced lung wet/dry weight ratio and an increased survival rate of the mice. Concomitantly, agomiR-93 significantly reduced LPS-induced the interleukin (IL)-6, IL-1β, and tumor necrosis factor (TNF)-α levels in BALF. Of note, Toll-like receptor 4 (TLR4), an upstream regulator of the nuclear factor (NF)-κB signaling pathway, was directly suppressed by miR-93 in RAW 264.7 cells. Importantly, agomiR-93 induced a significant suppression of the TLR4/myeloid differentiation primary response 88 (MyD88)/NF-κB signaling pathway, as demonstrated by the downregulation of MyD88, and the phosphorylation of IκB-α and p65 in the lung tissues of mice with ALI. Taken together, the findings of the present study indicate that miR-93 attenutes LPS-induced lung injury by regulating the TLR4/MyD88/NF-κB signaling pathway, suggesting that miR-93 may prove to be a potential therapeutic target for ALI.

MicroRNA‑24 attenuates diabetic vascular remodeling by suppressing the NLRP3/caspase‑1/IL‑1β signaling pathway

Vascular remodeling plays an important role in the pathogenesis of diabetic cardiovascular complications. Previous published research has indicated that microRNA-24 (miR-24) is involved in diabetic vascular remodeling, but the underlying molecular mechanisms have yet to be fully elucidated. The aim of the present study was to investigate whether adenovirus-mediated miR-24 overexpression can suppress the NOD-like receptor family pyrin domain-containing 3 (NLRP3)-related inflammatory signaling pathway and attenuate diabetic vascular remodeling. The carotid arteries of diabetic rats were harvested and prepared for analysis. Reverse transcription-quantitative PCR and western blotting assays were used to detect the expressions of related mRNAs and proteins. Morphological examinations, including hematoxylin and eosin, immunohistochemical and Masson’s trichrome staining, were also performed. The results of the present study demonstrated that miR-24 upregulation suppressed neointimal hyperplasia and accelerated reendothelialization in the injured arteries, lowered the expression of NLRP3, apoptosis-associated speck-like protein, caspase-1, proliferating cell nuclear antigen, CD45, interleukin (IL)-1β, IL-18 and tumor necrosis factor-α, and increased the expression of CD31, smooth muscle (SM) α-actin and SM-myosin heavy chain. These data indicated that miR-24 overexpression can attenuate vascular remodeling in a diabetic rat model through suppressing the NLRP3/caspase-1/IL-1β signaling pathway.

A novel inhibitory role of microRNA-224 in particulate matter 2.5-induced asthmatic mice by inhibiting TLR2

Epidemiological studies have shown that elevated concentrations of particulate matter 2.5 (PM2.5) correlate with increased incidence of asthma. Studies have highlighted the implication of microRNAs (miRNAs) in asthmatic response. Here, the objective of this study is to explore the effect of miR-224 on PM2.5-induced asthmatic mice. Ovalbumin (OVA) was utilized to establish asthmatic mouse models, which were then exposed to PM2.5, followed by miR-224 expression detection. Next, lesions and collagen deposition area in lung tissue, ratio Treg/Th17, the expression of TLR4 and MYD88, inflammation, eosinophils (EOS) and airway remodelling were evaluated in OVA mice after injection with miR-224 agomir. Following isolation of mouse primary bronchial epithelial cells, miR-224 mimic and TLR2/TLR4 inhibitor were introduced to assess inflammation and the expression of TGF-β, MMP9, TIMP-1, Foxp3, RORγt, TLR2, TLR4 and MYD88. After exposure to PM2.5, lesions and collagen deposition were promoted in lung tissues, inflammation and EOS were increased in bronchoalveolar lavage fluid (BALF), and airway remodelling was enhanced in OVA mice. miR-224 was down-regulated, whereas TLR2/TLR4/MYD88 was up-regulated in OVA mice after treatment with PM2.5, accompanied by Treg/Th17 immune imbalance. Of note, bioinformatic prediction and dual luciferase reporter gene assay confirmed that TLR2 was a target gene of miR-224. Overexpressed miR-224 reduced expression of TGF-β, MMP9, TIMP-1 and RORγt and inflammation but increased Foxp3 expression in bronchial epithelial cells through down-regulating TLR2. In summary, overexpressed miR-224 suppressed airway epithelial cell inflammation and airway remodelling in PM2.5-induced asthmatic mice through decreasing TLR2 expression.

Novel noncoding RNAs biomarkers in acute respiratory distress syndrome

Introduction: Acute respiratory distress syndrome (ARDS) is a very common condition associated with critically ill patients, which causes substantial morbidity and mortality. Currently, there is no effective clinical ARDS treatment strategy. Novel targets that effectively treat ARDS need to be found.Areas covered: Data sources were published articles through June 2019 in PubMed using the following keywords: 'acute respiratory distress syndrome,' 'miRNAs,' 'lncRNAs,' and 'biomarkers.' The selection of studies focused on in cellular model, animal model, and clinical studies of ARDS.Expert commentary: Accumulated evidence revealed that some specific miRNAs and lncRNAs could regulate the signaling pathways of the pathophysiology by targeting specific molecule in ARDS. The differentially expressed miRNAs exert a crucial role in apoptosis of neutrophil, antigen-presenting cells and lung epithelial cell, and the dysfunction of mitochondrial. Recently, the influence of lncRNAs upon miRNA function is also rapidly emerging. In some cases, lncRNA MALAT1 target TLR4 to mediate the p38 MAPK and NF-κB signaling pathway in ARDS rat model. In other cases, lncRNA CASC2 was found to act as a ceRNA of miR-144-3p which directly targeted AQP1 in LPS-induced A549 cell. In addition, other miRNA-lncRNA regulatory patterns in ARDS and novel biomarkers still require deeper research.

Bta-miR-24-3p Controls the Myogenic Differentiation and Proliferation of Fetal, Bovine, Skeletal Muscle-Derived Progenitor Cells by Targeting ACVR1B

Simple Summary

MicroRNAs play pivotal roles in skeletal muscle development, but the molecular basis of their functions in fetal bovine skeletal muscle development is largely unknown. Here, we report a mechanistic study of bta-miR-24-3p, a key miRNA regulator of the myogenic differentiation of fetal bovine platelet-derived growth factor receptor alpha negative (PDGFRα^-) progenitor cells. We isolated progenitor cells from the bovine fetal longissimus dorsi muscle and purified them with PDGFRα antibodies to remove fibro-adipogenic progenitors. We observed elevated bta-miR-24-3p expression during differentiation, and bta-miR-24-3p overexpression led to promoted myogenic differentiation but suppressed proliferation. Moreover, activin receptor type 1B (ACVR1B) was identified as a direct target of bta-miR-24-3p, and ACVR1B-silencing cells exhibited similar phenotypes to bta-miR-24-3p-overexpressing bovine PDGFRα^- progenitor cells. These results extended our understanding on the roles of miRNA in fetal muscle development. The method of removing fibro-adipogenic progenitors in our study will also provide useful information for other investigators.

Abstract

MicroRNAs modulate a variety of cellular events, including skeletal muscle development, but the molecular basis of their functions in fetal bovine skeletal muscle development is poorly understood. In this study, we report that bta-miR-24-3p promotes the myogenic differentiation of fetal bovine PDGFRα^- progenitor cells. The expression of bta-miR-24-3p increased during myogenic differentiation. Overexpression of bta-miR-24-3p significantly promoted myogenic differentiation, but inhibited proliferation. A dual-luciferase assay identified ACVR1B as a direct target of bta-miR-24-3p. Similarly, knocking down ACVR1B by RNA interference also significantly inhibited proliferation and promoted the differentiation of bovine PDGFRα^- progenitor cells. Thus, our study provides a mechanism in which bta-miR-24-3p regulates myogenesis by inhibiting ACVR1B expression.

Carbon Monoxide Attenuates Lipopolysaccharides (LPS)-Induced Acute Lung Injury in Neonatal Rats via Downregulation of Cx43 to Reduce Necroptosis

Background

Acute lung injury (ALI) is one of major causes of death in newborns, making it urgent to improve therapy. Administration of low dose carbon monoxide (CO) plays a protective role in ALI but the mechanisms are not fully understood. This study was designed to test the therapeutic effect of monoxide-releasing molecule 3 (MORM3) in lipopolysaccharide (LPS) induced neonatal ALI and the possibly associated molecular mechanisms.

Material/Methods

For this study, 3- to 8-day old Newborn Sprague-Dawley rats were subjected to intraperitoneal injection of 3 mg/kg LPS to induce ALI. Then animals received intraperitoneal injection of carbon monoxide-releasing molecules 3 (CORM3) (8 mg/kg) or inactive CORM3 (iCORM3) for 7 consecutive days. Lung tissues were collected for histological examination and total cell counts and protein content in bronchoalveolar lavage fluid (BALF) were measured. Expression of Cx43 and necroptosis-related markers were detected by quantitative real-time polymerase chain reaction (qRT-PCR) and western blot.

Results

LPS exposure induced significant lung injury indicated by histological damage, increased lung wet/dry weight ratio (W/D) and increased total cell counts and protein concentration in BALF. These changes were significantly ameliorated by administration of CORM3 but not iCORM3. LPS also increased necroptosis-related markers RIP1, RIP3, and MLKL and their elevation was blocked by CORM3. CORM3 administration ameliorated LPS induced elevation of Cx43 expression and adenoviral overexpression of Cx43 abolished lung protective effect of CORM3. CORM3 administration attenuated LPS induced activation of extracellular-signal-regulated kinase (ERK) and its protection against necroptosis was abolished by ERK inhibitor U0126.

Conclusions

CORM3 attenuates LPS-Induced ALI in neonatal rats and its lung protective effect might be through downregulation of Cx43 to attenuate ERK signaling and ameliorate necroptosis, suggesting CORM3 as a potential therapeutic drug for ALI in neonates.