Human lung macrophages: roll up for the MISTRG tour

Increased Levels of hsa-miR-199a-3p and hsa-miR-382-5p in Maternal and Neonatal Blood Plasma in the Case of Placenta Accreta Spectrum

Despite the increasing number of placenta accreta spectrum (PAS) cases in recent years, its impact on neonatal outcomes and respiratory morbidity, as well as the underlying pathogenetic mechanism, has not yet been extensively studied. Moreover, no study has yet demonstrated the effectiveness of antenatal corticosteroid therapy (CT) for the prevention of respiratory distress syndrome (RDS) in newborns of mothers with PAS at the molecular level. In this regard, microRNA (miRNA) profiling by small RNA deep sequencing and quantitative real-time PCR was performed on 160 blood plasma samples from preterm infants (gestational age: 33-36 weeks) and their mothers who had been diagnosed with or without PAS depending on the timing of the antenatal RDS prophylaxis. A significant increase in hsa-miR-199a-3p and hsa-miR-382-5p levels was observed in the blood plasma of the newborns from mothers with PAS compared to the control group. A clear trend toward the normalization of hsa-miR-199a-3p and hsa-miR-382-5p levels in the neonatal blood plasma of the PAS groups was observed when CT was administered within 14 days before delivery, but not beyond 14 days. Direct correlations were found among the hsa-miR-382-5p level in neonatal blood plasma and the hsa-miR-199a-3p level in the same sample (r = 0.49; p < 0.001), the oxygen requirements in the NICU (r = 0.41; p = 0.001), the duration of the NICU stay (r = 0.31; p = 0.019), and the severity of the newborn's condition based on the NEOMOD scale (r = 0.36; p = 0.005). Logistic regression models based on the maternal plasma levels of hsa-miR-199a-3p and hsa-miR-382-5p predicted the need for cardiotonic therapy, invasive mechanical ventilation, or high-frequency oscillatory ventilation in newborns during the early neonatal period, with a sensitivity of 95-100%. According to the literary data, these miRNAs regulate fetal organogenesis via IGF-1, the formation of proper lung tissue architecture, surfactant synthesis in alveolar cells, and vascular tone.

Crosstalk between macrophages and immunometabolism and their potential roles in tissue repair and regeneration

Immune metabolism is a result of many specific metabolic reactions, such as glycolysis, the tricarboxylic acid (TCA) pathway, the pentose phosphate pathway (PPP), mitochondrial oxidative phosphorylation (OXPHOS), fatty acid oxidation (FAO), fatty acid biosynthesis (FAs) and amino acid pathways, which promote cell proliferation and maintenance with structural and pathological energy to regulate cellular signaling. The metabolism of macrophages produces many metabolic intermediates that play important regulatory roles in tissue repair and regeneration. The metabolic activity of proinflammatory macrophages (M1) mainly depends on glycolysis and the TCA cycle system, but anti-inflammatory macrophages (M2) have intact functions of the TCA cycle, which enhances FAO and is dependent on OXPHOS. However, the metabolic mechanisms of macrophages in tissue repair and regeneration have not been well investigated. Thus, we review how three main metabolic mechanisms of macrophages, glucose metabolism, lipid metabolism, and amino acid metabolism, regulate tissue repair and regeneration.

Developing Humanized Animal Models with Transplantable Human iPSC-Derived Cells

Establishing reliable and reproducible animal models for disease modelling, drug screening and the understanding of disease susceptibility and pathogenesis is critical. However, traditional animal models differ significantly from humans in terms of physiology, immune response, and pathogenesis. As a result, it is difficult to translate laboratory findings into biomedical applications. Although several animal models with human chimeric genes, organs or systems have been developed in the past, their limited engraftment rate and physiological functions are a major obstacle to realize convincing models of humans. The lack of human transplantation resources and insufficient immune tolerance of recipient animals are the main challenges that need to be overcome to generate fully humanized animals. Recent advances in gene editing and pluripotent stem cell-based xenotransplantation technologies offer opportunities to create more accessible human-like models for biomedical research. In this article, we have combined our laboratory expertise to summarize humanized animal models, with a focus on hematopoietic/immune system and liver. We discuss their generation strategies and the potential donor cell sources, with particular attention given to human pluripotent stem cells. In particular, we discuss the advantages, limitations and emerging trends in their clinical and pharmaceutical applications. By providing insights into the current state of humanized animal models and their potential for biomedical applications, this article aims to advance the development of more accurate and reliable animal models for disease modeling and drug screening.

MiR-199a-3p-regulated alveolar macrophage-derived secretory autophagosomes exacerbate lipopolysaccharide-induced acute respiratory distress syndrome

Purpose

Acute respiratory distress syndrome (ARDS) is a prevalent illness in intensive care units. Extracellular vesicles and particles released from activated alveolar macrophages (AMs) assist in ARDS lung injury and the inflammatory process through mechanisms that are unclear. This study investigated the role of AM-derived secretory autophagosomes (SAPs) in lung injury and microRNA (MiR)-199a-3p-regulated inflammation associated with ARDS in vitro and in a murine model.

Methods

The ARDS model in mouse was established by intratracheal LPS lipopolysaccharide (LPS) injection. The agomirs or antagomirs of MiR-199a-3p were injected into the caudal vein to figure out whether MiR-199a-3p could influence ARDS inflammation and lung injury, whereas the mimics or inhibitors of MiR-199a-3p, siRNA of Rab8a, or PAK4 inhibitor were transfected or applied to RAW264.7 cells to evaluate the mechanism of SAP release. Culture supernatants of RAW264.7 cells treated with LPS or bronchoalveolar lavage fluid from mice were collected for the isolation of SAPs.

Results

We found that MiR-199a-3p was over-expressed in the lungs of ARDS mice. The MiR-199a-3p antagomir alleviated, whereas the MiR-199a-3p agomir exacerbated LPS-induced inflammation in mice by promoting AM-derived SAP secretion. In addition, MiR-199a-3p over-expression exacerbated LPS-induced ARDS via activating Rab8a, and Rab8a silencing significantly suppressed the promoting influence of the MiR-199a-3p mimic on SAP secretion. Furthermore, MiR-199a-3p mimic activated Rab8a by directly inhibiting PAK4 expression.

Conclusion

The novel finding of this study is that MiR-199a-3p participated in the regulation of SAP secretion and the inflammatory process via targeting of PAK4/Rab8a, and is a potential therapeutic candidate for ARDS treatment.

Secretory Autophagosomes from Alveolar Macrophages Exacerbate Acute Respiratory Distress Syndrome by Releasing IL-1β

Purpose

Activated alveolar macrophages (AMs) secrete extracellular vesicles and particles to mediate the inflammatory response in the acute respiratory distress syndrome (ARDS) although the underlying mechanisms are poorly understood. This study investigated whether secretory autophagosomes (SAPs) from AMs contribute to the inflammation-mediated lung injury of ARDS.

Methods

We first isolated SAPs from cell culture supernatants of RAW264.7 cells and AMs and quantified Interleukin (IL)-1β levels in SAPs. Next, we employed a lipopolysaccharide (LPS)-induced ARDS model to investigate whether SAP-derived IL-1β could exacerbate lung injury. Finally, we used siRNA to knockdown Rab8a, both in vitro and in vivo, to investigate the effect of Rab8a on SAP secretion and lung injury in ARDS.

Results

We found that AMs play an important role in ARDS by releasing a novel type of proinflammatory vesicles called SAPs that could exacerbate lung injury. SAPs are characterized as double-membrane vesicles (diameter ~200 nm) with the expression of light chain 3 (LC3). IL-1β in SAPs is the key factor that contributes to the inflammation and lung injury in ARDS. We found that Rab8a is necessary for AMs to release SAPs with IL-1β, and Rab8a knockdown alleviated lung injury in ARDS.

Conclusion

This study showed the novel finding that SAPs released from AMs play a vital role in ARDS by promoting an inflammatory response and the underlying mechanism was associated with IL-1β secretion.