Activation of the mTOR/HIF-1α/VEGF axis promotes M1 macrophage polarization in non-eosinophilic chronic rhinosinusitis with nasal polyps

Exosome-shuttled miR-150-5p from LPS-preconditioned mesenchymal stem cells down-regulate PI3K/Akt/mTOR pathway via Irs1 to enhance M2 macrophage polarization and confer protection against sepsis

Rationale

Sepsis is a life-threatening organ dysfunction and lack of effective measures in the current. Exosomes from mesenchymal stem cells (MSCs) reported to alleviate inflammation during sepsis, and the preconditioning of MSCs could enhance their paracrine potential. Therefore, this study investigated whether exosomes secreted by lipopolysaccharide (LPS)-pretreated MSCs exert superior antiseptic effects, and explored the underlying molecular mechanisms.

Methods

Exosomes were isolated and characterized from the supernatants of MSCs. The therapeutic efficacy of normal exosomes (Exo) and LPS-pretreated exosomes (LPS-Exo) were evaluated in terms of survival rates, inflammatory response, and organ damage in an LPS-induced sepsis model. Macrophages were stimulated with LPS and treated with Exo or LPS-Exo to confirm the results of the in vivo studies, and to explain the potential mechanisms.

Results

LPS-Exo were shown to inhibit aberrant pro-inflammatory cytokines, prevent organ damages, and improve survival rates of the septic mice to a greater extent than Exo. In vitro, LPS-Exo significantly promoted the M2 polarization of macrophages exposed to inflammation. miRNA sequencing and qRT-PCR analysis identified the remarkable expression of miR-150-5p in LPS-Exo compared to that in Exo, and exosomal miR-150-5p was transferred into recipient macrophages and mediated macrophage polarization. Further investigation demonstrated that miR-150-5p targets Irs1 in recipient macrophages and subsequently modulates macrophage plasticity by down-regulating the PI3K/Akt/mTOR pathway.

Conclusion

The current findings highly suggest that exosomes derived from LPS pre-conditioned MSCs represent a promising cell-free therapeutic method and highlight miR-150-5p as a novel molecular target for regulating immune hyperactivation during sepsis.

Deficiency of INPP4A promotes M2 macrophage polarization in eosinophilic chronic rhinosinusitis with nasal polyps

OBJECTIVE

The treatment of eosinophilic chronic rhinosinusitis with nasal polyps (E-CRSwNP) remains a challenge due to its complex pathogenesis. Inositol polyphosphate-4-phosphatase type IA (INPP4A), a lipid phosphatase, has been implicated in allergic asthma. However, the expression and function of INPP4A in E-CRSwNP remain unclear. This study aims to investigate the role of INPP4A in macrophages in E-CRSwNP.

METHODS

We assessed the expression of INPP4A in human and mouse nasal mucosal tissues via immunofluorescence staining. THP-1 cells were cultured and exposed to various cytokines to investigate the regulation of INPP4A expression and its functional role. Additionally, we established a murine nasal polyp (NP) model and administrated an INPP4A-overexpressing lentivirus evaluate its impact on NP.

RESULTS

The percentage of INPP4A + CD68 + macrophages among total macrophages decreased in the E-CRSwNP group compared to the control and the non-eosinophilic CRSwNP (NE-CRSwNP) groups, exhibiting an inverse correlation with an increased percentage of CD206 + CD68 + M2 macrophages among total macrophages. Overexpression of INPP4A led to a reduced percentage of THP-1 cells polarizing towards the M2 phenotype, accompanied by decreased levels of associated chemotactic factors including CCL18, CCL22, CCL24, and CCL26. We also validated the involvement of the PI3K-AKT pathway in the function of INPP4A in vitro. Furthermore, INPP4A overexpression in the murine NP model resulted in the attenuation of eosinophilic inflammation in the nasal mucosa.

CONCLUSIONS

INPP4A deficiency promotes macrophage polarization towards the M2 phenotype, leading to the secretion of chemokines that recruit eosinophils and Th2 cells, thereby amplifying eosinophilic inflammation in E-CRSwNP. INPP4A may exert a suppressive role in eosinophilic inflammation and could potentially serve as a novel therapeutic strategy.

Systemic Lipopolysaccharide Exposure Exacerbates Choroidal Neovascularization in Mice

This study aims to investigate the effect of a systemic lipopolysaccharide (LPS) stimulus in the course of laser-induced choroidal neovascularization (CNV) in C57BL/6 J mice. A group of CNV-subjected mice received 1 mg/kg LPS via the tail vein immediately after CNV induction. Mouse eyes were monitored in vivo with fluorescein angiography for 2 weeks. In situ hybridization and flow cytometry were performed in the retina at different time points. LPS led to increased fluorescein leakage 3 days after CNV, correlated with a large influx of monocyte-derived macrophages and increase of pro-inflammatory microglia/macrophages in the retina. Additionally, LPS enhanced Vegfα mRNA expression by Glul-expressing cells but not Aif1 positive microglia/macrophages in the laser lesion. These findings suggest that systemic LPS exposure has transient detrimental effects in the course of CNV through activation of microglia/macrophages to a pro-inflammatory phenotype and supports the important role of these cells in the CNV course.

Functionalized Magnesium Phosphate Cement Induces In Situ Vascularized Bone Regeneration via Surface Lyophilization of Chondroitin Sulfate

Bone defect repair poses significant challenges in orthopedics, thereby increasing the demand for bone substitutes. Magnesium phosphate cements (MPCs) are widely used for bone defect repair because of their excellent mechanical properties and biodegradability. However, high crystallinity and uncontrolled magnesium ion (Mg2+) release limit the surface bioactivity of MPCs in bone regeneration. Here, we fabricate chondroitin sulfate (CS) as a surface coating via the lyophilization method, namely CMPC. We find that the CS coating is uniformly distributed and improves the mechanical properties of MPC through anionic electrostatic adsorption, while mediating degradation-related controlled ion release of Mg2+. Using a combination of in vitro and in vivo analyses, we show that the CS coating maintained cytocompatibility while increasing the cell adhesion area of MC3T3-E1s. Furthermore, we display accelerated osteogenesis and angiogenesis of CMPC, which are related to appropriate ion concentration of Mg2+. Our findings reveal that the preparation of a lyophilized CS coating is an effective method to promote surface bioactivity and mediate Mg2+ concentration dependent osteogenesis and angiogenesis, which have great potential in bone regeneration.

Nuciferine protects against lipopolysaccharide-induced endometritis via inhibiting ferroptosis and modulating AMPKα/mTOR/HIF-1α signaling axis

Nuciferine (NF) is an alkaloid isolated from Nelumbo nucifera and has been reported to exhibit a wide range of pharmacological effects. However, whether NF treatment exhibits a protective effect in endometritis remains unclear. Here, the protective effects of NF on lipopolysaccharide (LPS)-induced endometritis in mice were investigated in our research. The results showed that NF significantly reversed the uterine histopathological changes, inflammatory factor levels and myeloperoxidase (MPO) activity caused by LPS. Furthermore, we found that NF administration improved the reproductive capacity of mice with endometritis. Mechanistically, the expression of MyD88/nuclear factor-kappa B (NF-κB) and MAPK-related proteins in uterine tissue were decreased by NF treatment. Moreover, we observed the occurrence of ferroptosis in the LPS-induced endometritis mouse model, which was noticeably inhibited by NF treatment. In addition, we showed that NF exhibited anti-endometritis activity by modulating AMPKα/mTOR/HIF1α signaling axis. Finally, the molecular mechanism of the NF anti-inflammatory effect was clarified in mouse endometrial epithelial cells (mEECs). NF inhibited the releases of pro-inflammatory factors in LPS-induced mEECs via inhibiting NF-κB signaling pathway. All these findings suggest that NF may ameliorate LPS-induced endometritis caused by LPS, the mechanism of action is related to the ferroptosis, MyD88/NF-κB, MAPK and AMPKα/mTOR/HIF1α signaling pathway.

Hypoxic State of Cells and Immunosenescence: A Focus on the Role of the HIF Signaling Pathway

Hypoxia activates hypoxia-related signaling pathways controlled by hypoxia-inducible factors (HIFs). HIFs represent a quick and effective detection system involved in the cellular response to insufficient oxygen concentration. Activation of HIF signaling pathways is involved in improving the oxygen supply, promoting cell survival through anaerobic ATP generation, and adapting energy metabolism to meet cell demands. Hypoxia can also contribute to the development of the aging process, leading to aging-related degenerative diseases; among these, the aging of the immune system under hypoxic conditions can play a role in many different immune-mediated diseases. Thus, in this review we aim to discuss the role of HIF signaling pathways following cellular hypoxia and their effects on the mechanisms driving immune system senescence.

The role of hypoxia in the pathophysiology of chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a chronic inflammatory disease of the nasal cavity characterized by excessive nasal mucus secretion and nasal congestion. The development of CRS is related to pathological mechanisms induced by hypoxia. Under hypoxic conditions, the stable expression of both Hypoxia inducible factor-1 (HIF-1) α and HIF-2α are involved in the immune response and inflammatory pathways of CRS. The imbalance in the composition of nasal microbiota may affect the hypoxic state of CRS and perpetuate existing inflammation. Hypoxia affects the differentiation of nasal epithelial cells such as ciliated cells and goblet cells, induces fibroblast proliferation, and leads to epithelial-mesenchymal transition (EMT) and tissue remodeling. Hypoxia also affects the proliferation and differentiation of macrophages, eosinophils, basophils, and mast cells in sinonasal mucosa, and thus influences the inflammatory state of CRS by regulating T cells and B cells. Given the multifactorial nature in which HIF is linked to CRS, this study aims to elucidate the effect of hypoxia on the pathogenic mechanisms of CRS.

Echinococcus multilocularis protoscoleces enhance glycolysis to promote M2 Macrophages through PI3K/Akt/mTOR Signaling Pathway

Alveolar Echinococcosis (AE) is a zoonotic parasitic disease caused by Echinococcus multilocularis, but its pathogenesis remains unclear. The primary objective of this study is to explore whether Echinococcus multilocularis protoscoleces (PSCs) regulate macrophage polarization and glucose metabolism by PI3K/Akt/mTOR signaling pathway. We found that large numbers of CD68⁺ macrophages gathered in close liver issue from the lesion in AE patients. PSCs preferentially differentiated into M2 macrophages and the expressions of HK1, PFKL, PKM2, PI3K, Akt, p-Akt, mTOR and p-mTOR increased. The above results show that Echinococcus multilocularis protoscoleces enhance glycolysis to promote M2 macrophages through PI3K/Akt/mTOR signaling pathway.

XBP1 Regulates the Transcription of HIF-1a in BALB/c Mice with Chronic Rhinosinusitis without Polyps

X-box binding protein 1 (XBP1) is a transcription factor that recognizes the CRE-like element in enhancers of human T-cell leukemia virus and MHC class II gene and induces their transcription. This study was performed to characterize the function of XBP1, which was identified to be a differentially expressed gene via GEO database, in chronic rhinosinusitis (CRS) without nasal polyps (CRSsNP). XBP1 expression was significantly elevated in both CRSsNP patients and mice who were accompanied with mucosal thickening, goblet cell hyperplasia and chemosis, glandular hyperplasia, and dense infiltration of inflammatory cells. Silencing of XBP1 suppressed the development of CRSsNP in mice. Mechanistically, knockdown of XBP1 downregulated the expression of hypoxia-inducible factor 1-alpha (HIF-1a), and overexpression of XBP1 led to the opposite result. Silencing of HIF-1a inhibited β-catenin expression and impaired the Wnt/β-catenin pathway. Further overexpression of HIF-1a in XBP1-silenced CRSsNP mice exacerbated pathological changes in mouse nasal mucosal tissues, promoted inflammation, and activated the Wnt/β-catenin pathway. Taken together, overexpression of XBP1 may be associated with increased expression of HIF-1a and possibly contribute to the Wnt/β-catenin pathway activation and the development of CRSsNP.

Advances in chronic rhinosinusitis in 2020 and 2021

Major progress has been achieved in the understanding and clinical practice of chronic rhinosinusitis, with or without nasal polyps. These advances resulted in a better understanding of the pathophysiology, the distribution into subgroups, and consequently in a better management perspective using classical approaches and biologics. Pathomechanisms, endotypes and biomarkers, and finally innovative therapeutic approaches are themes especially for the more severe forms of chronic rhinosinusitis, those with uncontrolled severe nasal polyps. Biologicals against key type 2 cytokines are gaining ground in the long-term treatment approaches of often recurrent nasal polyps, and should be integrated in care pathways making use of classical and innovative treatment pathways. These areas of interest show a fast development and will profoundly change our disease management within a decade.