miR‑351‑5p aggravates lipopolysaccharide‑induced acute lung injury via inhibiting AMPK

AMPK regulates immature boar Sertoli cell proliferation through affecting CDK4/Cyclin D3 pathway and mitochondrial function

Sertoli cell (SC) proliferation plays an important role in sperm production and quality; however, the regulatory mechanism of SC proliferation is not well understood. This study investigated the role of adenosine monophosphate-activated protein kinase (AMPK) in the regulation of immature boar SC activity. Cell counting kit-8, Seahorse XFe96, mitochondrial respiratory enzyme-related assay kits, and transmission electron microscopy were used to detect SC proliferative viability, oxygen consumption rate (OCR), mitochondrial respiratory enzyme activity, and the ultrastructure of primary cultured SCs in vitro from the testes of 21-day-old boars. A dual luciferase reporter assay was performed to determine the miRNA-mRNA target interaction. Western blotting was used to analyze cell proliferation-related protein expression of p38, p21, proliferating cell nuclear antigen (PCNA), Cyclin-dependent kinase 4 (CDK4), Cyclin D3, and phosphorylated retinoblastoma protein (Rb). Each experiment had a completely randomized design, with three replicates in each experiment. The results showed that the AMPK inhibitor (Compound C, 20 μM-24 h) increased cell proliferation viability, ATP production, and maximal respiration of SCs by 0.64-, 0.12-, and 0.08-fold (p < 0.05), respectively; increased the SC protein expression of PCNA, CDK4, Cyclin D3, and p-Rb by 0.13-, 0.09-, 0.88-, and 0.12-fold (p < 0.05), respectively; and decreased the SC protein expression of p38 and p21 by 0.36- and 0.27-fold (p < 0.05), respectively. The AMPK agonist AICAR (2 mM-6 h) significantly inhibited SC ultrastructure, OCR, mitochondrial respiratory enzyme activity, and cell proliferation-related protein levels. AMPK was validated to be a target gene of miR-1285 based on the result in which the miR-1285 mimic inhibited the luciferase activity of wild-type AMPK by 0.54-fold (p < 0.001). MiR-1285 mimic promoted the OCR of SCs, with 0.45-, 0.15-, 0.21-, and 0.30-fold (p < 0.01) increases in ATP production, basal and maximal respiration, and spare capacity, respectively. MiR-1285 mimic increased the mitochondrial respiratory enzyme activity of SCs, with 0.63-, 0.70-, and 0.97-fold (p < 0.01) increases in NADH-Q oxidoreductase, cytochrome c oxidase, and ATP synthase, respectively. Moreover, the miR-1285 mimic increased the protein expression of PCNA, CDK4, Cyclin D3, and p-Rb by 0.24-, 0.30-, 0.22-, and 0.13-fold (p < 0.05), respectively, and reduced the protein expression of p38 and p21 by 0.58- and 0.66-fold (p < 0.001). MiR-1285 inhibitor showed opposite effects on the above indicators and induced numerous autophagosomes and large lipid droplets in SCs. A high dose of estradiol (10 μM-6 h, showed a promotion of AMPK activation in a previous study) significantly inhibited SC ultrastructure, mitochondrial function, and proliferation-related pathways, while these adverse effects were weakened by Compound C treatment or miR-1285 mimic transfection. Our findings suggest that the activation and inhibition of AMPK induced by specific drugs or synthesized targeted miRNA fragments could regulate immature boar SC proliferative activity by influencing the CDK4/Cyclin D3 pathway and mitochondrial function; this helps to provide a basis for the prevention and treatment of male sterility in clinical practice.

Recent advances in cell membrane camouflaged nanotherapeutics for the treatment of bacterial infection

Infectious diseases caused by bacterial infections are common in clinical practice. Cell membrane coating nanotechnology represents a pioneering approach for the delivery of therapeutic agents without being cleared by the immune system in the meantime. And the mechanism of infection treatment should be divided into two parts: suppression of pathogenic bacteria and suppression of excessive immune response. The membrane-coated nanoparticles exert anti-bacterial function by neutralizing exotoxins and endotoxins, and some other bacterial proteins. Inflammation, the second procedure of bacterial infection, can also be suppressed through targeting the inflamed site, neutralization of toxins, and the suppression of pro-inflammatory cytokines. And platelet membrane can affect the complement process to suppress inflammation. Membrane-coated nanoparticles treat bacterial infections through the combined action of membranes and nanoparticles, and diagnose by imaging, forming a theranostic system. Several strategies have been discovered to enhance the anti-bacterial/anti-inflammatory capability, such as synthesizing the material through electroporation, pretreating with the corresponding pathogen, membrane hybridization, or incorporating with genetic modification, lipid insertion, and click chemistry. Here we aim to provide a comprehensive overview of the current knowledge regarding the application of membrane-coated nanoparticles in preventing bacterial infections as well as addressing existing uncertainties and misconceptions.

Preclinical evidence using synthetic compounds and natural products indicates that AMPK represents a potential pharmacological target for the therapy of pulmonary diseases

Adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) is a highly conserved eukaryotic enzyme discovered as a key regulator of cellular energy homeostasis, with anti-inflammation, antioxidative stress, anticancer, and antifibrosis beneficial effects. AMPK is dysregulated in human pulmonary diseases such as acute lung injury, nonsmall cell lung cancer, pulmonary fibrosis, chronic obstructive pulmonary disease, and asthma. This review provides an overview of the beneficial role of natural, synthetic, and Chinese traditional medicines AMPK modulators in pulmonary diseases, and highlights the role of the AMPK signaling pathway in the lung, emphasizing the importance of finding lead compounds and drugs that can target and modulate AMPK to treat the lung diseases.

MicroRNA-1258 suppresses oxidative stress and inflammation in septic acute lung injury through the Pknox1-regulated TGF-β1/SMAD3 cascade

AIM

The study was to clarify the mechanism of miR-1258 targeting Prep1 (pKnox1) to control Transforming Growth Factor β1 (TGF-β1)/SMAD3 pathway in septic Acute Lung Injury (ALI)-induced oxidative stress and inflammation.

METHODS

BEAS-2B cells and C57BL/6 mice were used to make in vitro and in vivo septic ALI models, respectively. miR-1258 expression was checked by RT-qPCR. After transfection in the in vitro experimental model, inflammation, oxidative stress, viability, and apoptosis were observed through ELISA, MTT, and flow cytometry.

RESULTS

In the in vivo model after miR-1258 overexpression treatment, inflammation, oxidative stress, and lung injury were further investigated. The targeting relationship between miR-1258 and Pknox1 was tested. Low miR-1258 was expressed in septic ALI patients, LPS-treated BEAS-2B cells, and mice. Upregulated miR-1258 prevented inflammation, oxidative stress, and apoptosis but enhanced the viability of LPS-treated BEAS-2B cells. The impact of upregulated miR-1258 on LPS-treated BEAS-2B cells was mitigated by inhibiting Pknox1 expression. MiR-1258 overexpression had the alleviating effects on inflammation, oxidative stress, and lung injury of LPS-injured mice through suppressing Pknox1 expression and TGF-β1/SMAD3 cascade activation.

CONCLUSIONS

The study concludes that miR-1258 suppresses oxidative stress and inflammation in septic ALI through the Pknox1-regulated TGF-β1/SMAD3 cascade.

miRNA-Mediated Fine Regulation of TLR-Induced M1 Polarization

Macrophage polarization to the M1 spectrum is induced by bacterial cell wall components through stimulation of Toll-like family (TLR) receptors. By orchestrating the expression of relevant mediators of the TLR cascade, as well as associated pathways and feedback loops, macrophage polarization is coordinated to ensure an appropriate immune response. This is central to the successful control of pathogens and the maintenance of health. Macrophage polarization is known to be modulated at both the transcriptional and post-transcriptional levels. In recent years, the miRNA-based post-transcriptional regulation of M1 polarization has received increasing attention from the scientific community. Comparative studies have shown that TLR stimulation alters the miRNA profile of macrophages and that macrophages from the M1 or the M2 spectrum differ in terms of miRNAs expressed. Simultaneously, miRNAs are considered critical post-transcriptional regulators of macrophage polarization. In particular, miRNAs are thought to play a regulatory role in the switch between the early proinflammatory response and the resolution phase. In this review, we will discuss the current state of knowledge on the complex interaction of transcriptional and post-transcriptional regulatory mechanisms that ultimately determine the functionality of macrophages.

Bisdemethoxycurcumin alleviates LPS-induced acute lung injury via activating AMPKα pathway

OBJECTIVE

Inflammation and oxidative stress contribute to the pathogenesis of acute lung injury (ALI), and subsequently result in rapid deterioration in health. Considering the indispensable role of bisdemethoxycurcumin (BDMC) in inflammation and oxidative stress, the present study aims to examine the effect of BDMC on sepsis-related ALI.

METHODS

C57BL/6 mice were administered with BDMC (100 mg/kg) or an equal volume of vehicle, and then injected with lipopolysaccharides (LPS) to induce ALI. We assessed the parameters of lung injury, inflammatory response and oxidative stress in lung tissues. Consistently, the macrophages with or without BDMC treatment were exposed to LPS to verify the effect of BDMC in vitro.

RESULTS

BDMC suppressed LPS-induced lung injury, inflammation and oxidative stress in vivo and in vitro. Mechanistically, BDMC increased the phosphorylation of AMPKα in response to LPS stimulation, and AMPK inhibition with Compound C almost completely blunted the protective effect of BDMC in LPS-treated mice and macrophages. Moreover, we demonstrated that BDMC activated AMPKα via the cAMP/Epac pathway.

CONCLUSION

Our study identifies the protective effect of BDMC against LPS-induced ALI, and the underlying mechanism may be related to the activation of cAMP/Epac/AMPKα signaling pathway.

MiR-217-5p inhibits smog (PM2.5)-induced inflammation and oxidative stress response of mouse lung tissues and macrophages through targeting STAT1

Objective: To explore the roles of macrophages’ miR-217-5p in the process of PM2.5 induced acute lung injury.

Methods: GEO database and KEGG pathway enrichment analysis as well as GSEA were used to predicted the miRNA and associated target signals. And then mice and RAW246.7 macrophages treated with PM2.5 to imitate PM2.5 induced acute lung injury environment and then transfected with miR-217-5p NC or miR-217-5p mimic. The levels of inflammatory factors TNF-α and anti-inflammatory factor IL-10 of mice serum were tested by ELISA. And the pathological changes and ROS level of mouse lung tissues were stained by HE and DHE staining. The proteins expression of phosphorylated-STAT1, total-STAT1, TNF-α, IFN-γ as well as p47, gp91, NOX4 in mice or RAW264.7 cells were tested by western blot or immunofluorescence of RAW264.7 cell slides.

Results: The results of bioinformatics analysis indicated the miR-217 as well as STAT1 were involved PM2.5 associated lung injury. After exposure to PM2.5, the decreased levels of serum TNF-α but not IL-10, consistent with reduced macrophages’ accumulation as well as decreased ROS levels in lung tissues in miR-217-5p mimic group vs miR-217-5p NC group mice, and moreover, the protein expression levels of phosphorylated--STAT1, total-STAT1, TNF-α, IFN-γ, p47, gp91 and NOX4 in mouse lung tissues and RTAW246.7 macrophages cells were all significantly reduced with miR-217-5p mimic administration. The above phenomena were reversed by specific STAT1-inhibitor HY-N8107.

Conclusions: miR-217-5p suppressed the activated STAT1-signal induced inflammation and oxidative stress trigged by PM2.5 in macrophages and resulted in the decreased lung injure caused by PM2.5.

Emerging Role of cAMP/AMPK Signaling

The 5′-Adenosine monophosphate (AMP)-activated protein kinase (AMPK) is a natural energy sensor in mammalian cells that plays a key role in cellular and systemic energy homeostasis. At the cellular level, AMPK supports numerous processes required for energy and redox homeostasis, including mitochondrial biogenesis, autophagy, and glucose and lipid metabolism. Thus, understanding the pathways regulating AMPK activity is crucial for developing strategies to treat metabolic disorders. Mounting evidence suggests the presence of a link between cyclic AMP (cAMP) and AMPK signaling. cAMP signaling is known to be activated in circumstances of physiological and metabolic stress due to the release of stress hormones, such as adrenaline and glucagon, which is followed by activation of membrane-bound adenylyl cyclase and elevation of cellular cAMP. Because the majority of physiological stresses are associated with elevated energy consumption, it is not surprising that activation of cAMP signaling may promote AMPK activity. Aside from the physiological role of the cAMP/AMPK axis, numerous reports have suggested its role in several pathologies, including inflammation, ischemia, diabetes, obesity, and aging. Furthermore, novel reports have provided more mechanistic insight into the regulation of the cAMP/AMPK axis. In particular, the role of distinct cAMP microdomains generated by soluble adenylyl cyclase in regulating basal and induced AMPK activity has recently been demonstrated. In the present review, we discuss current advances in the understanding of the regulation of the cAMP/AMPK axis and its role in cellular homeostasis and explore some translational aspects.