Mouse Bone Marrow Cell Isolation and Macrophage Differentiation

Sex-dimorphic gene regulation in murine macrophages across niches

Macrophages are a key cell type of the innate immune system and are involved at all steps of inflammation: (i) they present antigens to initiate inflammation, (ii) they clear up foreign bodies through phagocytosis and (iii) they resolve inflammation by removing or deactivating mediator cells. Many subtypes of macrophages have been identified, classified by their niche and/or embryonic origin. In order to better develop therapies for conditions with macrophage dysfunction, it is crucial to decipher potential sex differences in key physiological mediators of inflammation so that treatment efficacy can be ensured regardless of biological sex. Here, we conduct a meta-analysis approach of transcriptomics data sets for male vs. female mouse macrophages across 8 niches to characterize conserved sex-dimorphic pathways in macrophages across origins and niches. For this purpose, we leveraged new and publicly available RNA-sequencing data sets from murine macrophages, preprocessed these datasets and filtered them based on objective QC criteria, and performed differential gene expression analysis using sex as the covariate of interest. Differentially expressed (DE) genes were compared across data sets and macrophage subsets, and functional enrichment analysis was performed to identify sex-specific functional differences. Consistent with their presence on the sex chromosomes, three genes were found differentially expressed across datasets (i.e. Xist, Eif2s3y and Ddx3y). More broadly, we found that female-biased pathways across niches are more consistent than male-biased pathways, specifically relating to the extracellular matrix. Our findings increase our understanding of transcriptional similarities across macrophage niches and underscore the importance of including sex as a biological variable in immune-related studies.

Endothelial USP11 drives VEGFR2 signaling and angiogenesis via PRDX2/c-MYC axis

Angiogenesis is a crucial component of various physiological and pathological processes, including embryonic development, ischemic diseases, and tumor progression. Recent studies have highlighted the importance of ubiquitinases in angiogenesis. In this study, we utilized RNA sequencing data of the mouse retinal development model from the GEO database to identify the potential proangiogenic deubiquitinases and found USP11 was significantly upregulated. Although USP11 is known to regulate cell survival, DNA repair, and oxidative stress in cancers and ischemic conditions, its direct role in endothelial angiogenesis remains poorly understood. Here, we demonstrated that USP11 expression correlates with key pro-angiogenic genes and is significantly upregulated at both mRNA and protein levels in VEGF-treated human umbilical vein endothelial cells (HUVECs). USP11 knockout markedly inhibited angiogenesis both in vivo and in vitro, whereas USP11 overexpression promoted angiogenesis. Mechanistically, USP11 binds to PRDX2, facilitating the removal of its K63-linked polyubiquitination, which promotes its translocation into the nucleus. This facilitates the concurrent nuclear translocation of c-MYC, a PRDX2 interactor, which subsequently enhances the transcription of KDR (encoding VEGFR2) and activates the VEGFR2 signaling pathway. Our findings suggest that USP11 promotes angiogenesis by upregulating VEGFR2 expression through the PRDX2/c-MYC pathway, indicating that USP11 could serve as a potential target for clinical interventions in angiogenesis-related diseases.

Low-intensity ultrasound stimulation promotes differentiation of bone marrow mononuclear cells to nucleus pulposus cells for matrix synthesis

OBJECTIVE

To investigate the role of low-intensity ultrasound stimulation (LIUS) in facilitating the differentiation of bone marrow mononuclear cells (BMMNCs) into nucleus pulposus cells (NPCs) for matrix synthesis, offering a possible new therapeutic approach for intervertebral disc degeneration.

METHODS

Human BMMNCs and NPCs were cultured, and exosomes were extracted from NPCs using differential ultracentrifugation, followed by characterization. LIUS was utilized to evaluate exosome uptake, induce cell differentiation, measure apoptosis, and track DNA synthesis by EdU assays. Various experimental conditions were tested, including different LIUS intensities and differentiation durations. A range of detection techniques, such as RT-qPCR, western blotting, and cellular staining, were employed to monitor relevant indicators.

RESULTS

Exosomes were successfully isolated from NPCs, and their purity was confirmed using nanoparticle tracking analysis (NTA), transmission electron microscopy, and western blot. PKH67-labeled exosomes were internalized by BMMNCs during co-incubation. LIUS treatment at different intensities revealed that the LIUS-100 group exhibited the most significant cell proliferation, as shown by EdU assays. Flow cytometry revealed that the LIUS-100 and LIUS-150 groups demonstrated the most pronounced inhibition of apoptosis. In NPC exosome-induced differentiation experiments, the expression of relevant marker mRNA and protein levels increased over time under standard conditions, with even greater upregulation observed under LIUS-100 stimulation. Moreover, LIUS-100 enhanced the intracellular accumulation of glycosaminoglycans and proteoglycans, suggesting its role in promoting BMMNC differentiation into NPCs and matrix component synthesis.

CONCLUSION

NPC exosomes and LIUS are essential for guiding the differentiation of BMMNCs into NPCs, representing a promising therapeutic strategy for intervertebral disc degeneration. However, further in vivo studies are needed to refine LIUS technique, ensure safety, and evaluate long-term efficacy.

Polarized macrophage functions are affected differentially after CSF-1R inhibition with PLX5622

PLX5622 is a colony stimulating factor 1 receptor (CSF-1R) inhibitor that is known to deplete microglial cells in vivo. Recently its effects on macrophages (Mφ) were also observed in vivo. Therefore, we performed this study to assess its in vitro effects on the differentiation and functions of polarized Mφ derived from different tissues. Our findings show that addition of PLX5622 early on after ex vivo isolation hinders Mφ differentiation and survival. However, its addition post Mφ differentiation did not significantly affect the viability. Furthermore, PLX5622 affects certain functions and degree of polarization of IL-4 (M2a) Mφ but not polarization of M1-like Mφ. Our study provides novel aspects on the application of PLX5622 to study Mφ functions in vitro, where polarization is affected by CSF-1R signalling and provides distinctive evidence to its ability to affect certain populations of Mφ during in vitro differentiation and maturation.

Size-selective microfluidics delineate the effects of combinatorial immunotherapy on T-cell response dynamics at the single-cell level

Cellular communication at the single-cell level holds immense potential for uncovering response heterogeneity in immune cell behaviors. However, because of significant size diversity among different immune cell types, controlling the pairing of cells with substantial size differences remains a formidable challenge. We developed a microfluidic platform for size-selective pairing (SSP) to pair single cells with up to a fivefold difference in size, achieving over 40% pairing efficiency. We used SSP to investigate the real-time effects of combinatorial immunotherapeutic stimulation on macrophage T-cell interactions at the single-cell level via fluorescence microscopy and microfluidic sampling. While combinatorial activation involving toll-like receptor (TLR) agonists and rapamycin (an mTOR inhibitor) has improved therapeutic efficacy in mice, its clinical success has been limited. Here, we investigated immune synaptic interactions and outcomes at the single-cell level in real time and compared them with bulk-level measurements. Our findings, after tracking and computationally analyzing the effects of sequential and spatiotemporal stimulations of primary mouse macrophages, suggest a regulatory role of rapamycin in dampening inflammatory outputs in T cells.

Strain-specific differences in reovirus infection of murine macrophages segregate with polymorphisms in viral outer-capsid protein σ3

Mammalian orthoreovirus (reovirus) strains type 1 Lang (T1L) and type 3 Dearing-RV (T3D-RV) infect the intestine in mice but differ in the induction of inflammatory responses. T1L infection is associated with the blockade of oral immunological tolerance to newly introduced dietary antigens, whereas T3D-RV is not. T1L infection leads to an increase in infiltrating phagocytes, including macrophages, in gut-associated lymphoid tissues that are not observed in T3D-RV infection. However, the function of macrophages in reovirus intestinal infection is unknown. Using cells sorted from infected intestinal tissue and primary cultures of bone-marrow-derived macrophages (BMDMs), we discovered that T1L infects macrophages more efficiently than T3D-RV. Analysis of T1L × T3D-RV reassortant viruses revealed that the viral S4 gene segment, which encodes outer-capsid protein σ3, is responsible for strain-specific differences in infection of BMDMs. Differences in the binding of T1L and T3D-RV to BMDMs also segregated with the σ3-encoding S4 gene. Paired immunoglobulin-like receptor B (PirB), which serves as a receptor for reovirus, is expressed on macrophages and engages σ3. We found that PirB-specific antibody blocks T1L binding to BMDMs and that T1L binding to PirB-/- BMDMs is significantly diminished. Collectively, our data suggest that reovirus T1L infection of macrophages is dependent on engagement of PirB by viral outer-capsid protein σ3. These findings raise the possibility that macrophages function in the innate immune response to reovirus infection that blocks immunological tolerance to new food antigens.IMPORTANCEMammalian orthoreovirus (reovirus) infects humans throughout their lifespan and has been linked to celiac disease (CeD). CeD is caused by a loss of oral immunological tolerance (LOT) to dietary gluten and leads to intestinal inflammation following gluten ingestion, which worsens with prolonged exposure and can cause malnutrition. There are limited treatment options for CeD. While there are genetic risk factors associated with the illness, triggers for disease onset are not completely understood. Enteric viruses, including reovirus, have been linked to CeD induction. We found that a reovirus strain associated with oral immunological tolerance blockade infects macrophages by virtue of its capacity to bind macrophage receptor PirB. These data contribute to an understanding of the innate immune response elicited by reovirus, which may shed light on how viruses trigger LOT and inform the development of CeD vaccines and therapeutic agents.

Distinct immunomodulation elicited by young versus aged extracellular vesicles in bone marrow-derived macrophages

BACKGROUND

Previous research has indicated that extracellular vesicles (EVs) potentially play significant roles in multiple ageing phenotypes. This study uses a factorial experimental design to explore the interactions between circulating EVs and bone marrow-derived macrophages (BMDMs) isolated from young (7-12 weeks) and aged (70-90 weeks) mice.

RESULTS

In this study, plasma EVs from young (Y_EV) and aged (O_EV) mice were isolated and compared based on abundance, size, and miRNA cargo. Compared to some previous studies, we found relatively few differences in EV miRNA cargo between Y_EVs and O_EVs. Young and old EVs were then used to stimulate naïve BMDMs isolated from young (Y_BMDM) and aged (O_BMDM) mice. A panel of five "M1" and six "M2" macrophage markers were used to assess the degree of polarisation. Our results revealed differences in the immunomodulatory effects of Y_EVs and O_EVs in Y_BMDMs and O_BMDMs. Y_EVs induced less pro-inflammatory gene expression, while O_EVs exhibited a more varied impact, promoting both pro- and anti-inflammatory markers. However, neither EV population induced a clearly defined 'M1' or 'M2' macrophage phenotype. We also report that EVs elicited responses that differed markedly from those induced by whole plasma. Plasma from old mice had strong pro-inflammatory effects on Y_BMDMs, increasing Il1b, Nlrp3 and Tnfa. However, O_EVs did not have these effects, supporting current evidence that EVs are a separate component of circulating factors during ageing. More research is needed to elucidate specific factors involved in inflammageing processes.

CONCLUSIONS

Our findings reveal age-related differences in EV cargo and function, with young EVs tending to suppress inflammatory markers more effectively than aged EVs. However, this is not straightforward, and EVs often promoted both M1 and M2 markers. These results suggest that EVs are a distinct component of circulating factors and hold potential for therapeutic strategies aimed at mitigating age-related inflammation and immune dysregulation.

A Comprehensive Protocol for the Collection, Differentiation, Cryopreservation, and Resuscitation of Primary Murine Bone Marrow Derived Macrophages (BMDM)

BACKGROUND

The field of immunology has undoubtedly benefited from the in vitro use of cell lines for immunological studies; however, due to the "immortal" nature of many cell lines, they are not always the best model. Thus, direct collection and culture of primary cells from model organisms is a solution that many researchers utilize. To the best of our knowledge, there is not a singular protocol which encompasses the entire process of bone marrow cell collection through cryopreservation and resuscitation of cells from a murine model.

METHODS

Bone marrow cells were collected from mice with a C57BL6 genetic background. Cells were differentiated using L929 conditioned media. Cells were assessed using a combination of microscopy, differential staining, immunocytochemistry, and trypan blue. Results: Primary murine BMDMs that underwent cryopreservation followed by resuscitation retained a high degree of viability. Furthermore, these BMDMs retained on overall ability to clear S. aureus.

RESULTS

Primary murine BMDMs that underwent cryopreservation followed by resuscitation retained a high degree of viability. Furthermore, these BMDMs retained on overall ability to clear S. aureus.

CONCLUSION

Crypopreserved and resuscitated primary murine BMDMs were viable and retained their pverall S. aureus clearance ability.

Protocol for analyzing BCG-induced trained immunity in murine bone marrow-derived macrophages

Bacillus Calmette-Guérin (BCG), the only licensed tuberculosis vaccine, provides non-specific protection against non-tuberculosis diseases that is mediated by trained immunity, a functional reprogramming mediated by innate immune memory. Here, we present a protocol for analyzing BCG-induced trained immunity in murine bone marrow-derived macrophages (BMDMs). We describe steps for preparing BCG single bacterial suspensions, isolating BMDM cells, and the training process. This protocol can assist researchers to conveniently utilize BMDM cells to study trained immunity. For complete details on the use and execution of this protocol, please refer to Xu et al.1.

Y4 RNA fragments from cardiosphere-derived cells ameliorate diabetic myocardial ischemia‒reperfusion injury by inhibiting protein kinase C β-mediated macrophage polarization

The specific pathophysiological pathways through which diabetes exacerbates myocardial ischemia/reperfusion (I/R) injury remain unclear; however, dysregulation of immune and inflammatory cells, potentially driven by abnormalities in their number and function due to diabetes, may play a significant role. In the present investigation, we simulated myocardial I/R injury by inducing ischemia through ligation of the left anterior descending coronary artery in mice for 40 min, followed by reperfusion for 24 h. Previous studies have indicated that protein kinase Cβ (PKCβ) is upregulated under hyperglycemic conditions and is implicated in the development of various diabetic complications. The Y4 RNA fragment is identified as the predominant small RNA component present in the extracellular vesicles of cardio sphere-derived cells (CDCs), exhibiting notable anti-inflammatory properties in the contexts of myocardial infarction and cardiac hypertrophy. Our investigation revealed that the administration of Y4 RNA into the ventricular cavity of db/db mice following myocardial I/R injury markedly enhanced cardiac function. Furthermore, Y4 RNA was observed to facilitate M2 macrophage polarization and interleukin-10 secretion through the suppression of PKCβ activation. The mechanism by which Y4 RNA affects PKCβ by regulating macrophage activation within the inflammatory environment involves the inhibition of ERK1/2 phosphorylation In our study, the role of PKCβ in regulating macrophage polarization during myocardial I/R injury was investigated through the use of PKCβ knockout mice. Our findings indicate that PKCβ plays a crucial role in modulating the inflammatory response associated with macrophage activation in db/db mice experiencing myocardial I/R, with a notable exacerbation of this response observed upon significant upregulation of PKCβ expression. In vitro studies further elucidated the protective mechanism by which Y4 RNA modulates the PKCβ/ERK1/2 signaling pathway to induce M2 macrophage activation. Overall, our findings suggest that Y4 RNA plays an anti-inflammatory role in diabetic I/R injury, suggesting a novel therapeutic approach for managing myocardial I/R injury in diabetic individuals.

Phenotypic comparison and the potential antitumor function of immortalized bone marrow-derived macrophages (iBMDMs)

Introduction

Macrophages are an important component of innate immunity and involved in the immune regulation of multiple diseases. The functional diversity and plasticity make macrophages to exhibit different polarization phenotypes after different stimuli. During tumor progression, the M2-like polarized tumor-associated macrophages (TAMs) promote tumor progression by assisting immune escape, facilitating tumor cell metastasis, and switching tumor angiogenesis. Our previous studies demonstrated that functional remodeling of TAMs through engineered-modifying or gene-editing provides the potential immunotherapy for tumor. However, lack of proliferation capacity and maintained immune memory of infused macrophages restricts the application of macrophage-based therapeutic strategies in the repressive tumor immune microenvironment (TIME). Although J2 retrovirus infection enabled immortalization of bone marrow-derived macrophages (iBMDMs) and facilitated the mechanisms exploration and application, little is known about the phenotypic and functional differences among multi kinds of macrophages.

Methods

HE staining was used to detect the biosafety of iBMDMs, and real-time quantitative PCR, immunofluorescence staining, and ELISA were used to detect the polarization response and expression of chemokines in iBMDMs. Flow cytometry, scratch assay, real-time quantitative PCR, and crystal violet staining were used to analyze its phagocytic function, as well as its impact on tumor cell migration, proliferation, and apoptosis. Not only that, the inhibitory effect of iBMDMs on tumor growth was detected through subcutaneous tumor loading, while the tumor tissue was paraffin sectioned and flow cytometry was used to detect its impact on the tumor microenvironment.

Results

In this study, we demonstrated iBMDMs exhibited the features of rapid proliferation and long-term survival. We also compared iBMDMs with RAW264.7 cell line and mouse primary BMDMs with in vitro and in vivo experiments, indicating that the iBMDMs could undergo the same polarization response as normal macrophages with no obvious cellular morphology changes after polarization. What's more, iBMDMs owned stronger phagocytosis and pro-apoptosis functions on tumor cells. In addition, M1-polarized iBMDMs could maintain the anti-tumor phenotypes and domesticated the recruited macrophages of receptor mice, which further improved the TIME and repressed tumor growth.

Discussion

iBMDMs can serve as a good object for the function and mechanism study of macrophages and the optional source of macrophage immunotherapy.

Constitutive Plasma Membrane Turnover in T-REx293 cells via Ordered Membrane Domain Endocytosis under Mitochondrial Control

Clathrin/dynamin-independent endocytosis of ordered plasma membrane domains (ordered membrane domain endocytosis, OMDE) can become massive in response to cytoplasmic Ca elevations, G protein activation by non-hydrolyzable GTP analogs, and enhanced oxidative metabolism. In patch-clamped murine bone marrow macrophages (BMMs), cytoplasmic succinate and pyruvate, but not β-hydroxybutyrate, induce OMDE of 75% of the plasma membrane within 2 min. The responses require palmitoylation of membrane proteins, being decreased by 70% in BMMs lacking the acyltransferase, DHHC5, by treatment with carnitine to shift long-chain acyl groups from cytoplasmic to mitochondrial acyl-CoAs, by bromopalmitate/albumin complexes to block DHHCs, and by the mitochondria-specific cyclosporin, NIM811, to block permeability transition pores that may release mitochondrial coenzyme A into the cytoplasm. Using T-REx293 cells, OMDE amounts to 40% with succinate, pyruvate, or GTPγS, and it is inhibited by actin cytoskeleton disruption. Pyruvate-induced OMDE is blocked by the hydrophobic antioxidant, edaravone, which prevents permeability transition pore openings. Using fluorescent 3kD dextrans to monitor endocytosis, OMDE appears to be constitutively active in T-REx293 cells but not in BMMs. After 1 h without substrates or bicarbonate, pyruvate and hydroxybutyrate inhibit constitutive OMDE, as expected for a shift of CoA from long-chain acyl-CoAs to other CoA metabolites. In the presence of bicarbonate, pyruvate strongly enhances OMDE, which is then blocked by β-hydroxybutyrate, bromopalmitate/albumin complexes, cyclosporines, or edaravone. After pyruvate responses, T-REx293 cells grow normally with no evidence for apoptosis. Fatty acid-free albumin (15 μM) inhibits basal OMDE in T-REx293 cells, as do cyclosporines, carnitine, and RhoA blockade. Surprisingly, OMDE in the absence of substrates and bicarbonate is not inhibited by siRNA knockdown of the acyltransferases, DHHC5 or DHHC2, which are required for activated OMDE in patch clamp experiments. We verify biochemically that small CoA metabolites decrease long-chain acyl-CoAs. We verify also that palmitoylations of many PM-associated proteins decrease and increase when OMDE is inhibited and stimulated, respectively, by different metabolites. STED microscopy reveals that vesicles formed during constitutive OMDE in T-REX293 cells have 90 to 130 nm diameters. In summary, OMDE is likely a major G-protein-dependent endocytic mechanism that can be constitutively active in some cell types, albeit not BMMs. OMDE depends on different DHHC acyltransferases in different circumstances and can be limited by local supplies of fatty acids, CoA, and long-chain acyl-CoAs.

Low-density lipoprotein receptor-related protein 6 ablation in macrophages differentially inhibits lung injury-mediated inflammation and metastasis

Low-density lipoprotein receptor-related protein 6 (LRP6) is a receptor protein for Wnt ligands. Yet, their role in immune cell regulation remains elusive. Here we demonstrated that genetic deletion of LRP6 in macrophages using LysM-cre Lrp6fl/fl (Lrp6MKO) mice showed differential inhibition of inflammation in the bleomycin (BLM)-induced lung injury model and B16F10 melanoma lung metastasis model. Lrp6MKO mice showed normal immune cell populations in the lung and circulating blood in homeostatic conditions. In the BLM-induced lung injury model, Lrp6MKO mice showed a decreased number of monocyte-derived alveolar macrophages, reduced collagen deposition and alpha-smooth muscle actin (αSMA) protein levels in the lung. In B16F10 lung metastasis model, Lrp6MKO mice reduced lung tumor foci. Monocytic and granulocytic-derived myeloid-derived suppressor cells (M-MDSCs and G-MDSCs) were increased in the lung. In G-MDSCs, hypoxia-inducible factor 1α (HIF1α)+ PDL1+ population was markedly decreased but not in M-MDSCs. Taken together, our results show that the role of LRP6 in macrophages is differential depending on the inflammation microenvironment in the lung.

Thrombocyte-derived Dickkopf1 promotes macrophage polarization in the Bleomycin-induced lung injury model

Immune responses are crucial to maintaining tissue homeostasis upon tissue injury. Upon various types of challenges, macrophages play a central role in regulating inflammation and tissue repair processes. While an immunomodulatory role of Wnt antagonist Dickkopf1 (DKK1) has been implicated, the role of Wnt antagonist DKK1 in regulating macrophage polarization in inflammation and the tissue repair process remains elusive. Here we found that DKK1 induces gene expression profiles to promote inflammation and tissue repair in macrophages. Importantly, DKK1 induced various genes, including inflammation and tissue repair, via JNK (c-jun N-terminal kinase) in macrophages. Furthermore, DKK1 potentiated IL-13-mediated macrophage polarization and activation. The co-inhibition of JNK and STAT6 markedly decreased gene expressions relevant to inflammation and fibrosis by DKK1 and IL-13. Interestingly, thrombocyte-specific deletion of DKK1 in mice reduced collagen deposition and decreased Arg1, CD206, HIF1α, and IL1β protein expressions in monocyte-derived alveolar macrophages in the acute sterile bleomycin (BLM)-induced lung injury model. These data suggested that thrombocytes communicate with macrophages via DKK1 to orchestrate inflammation and repair in this model. Taken together, our study demonstrates DKK1's role as an important regulatory ligand for macrophage polarization in the injury-induced inflammation and repair process in the lung.

Vascular Cell Adhesion Molecule-1 (VCAM-1) contributes to macular fibrosis in neovascular age-related macular degeneration through modulating macrophage functions

BACKGROUND

Neovascular age-related macular degeneration (nAMD) is a major cause of blindness in the elderly. The disease is due to the growth of abnormal blood vessels into the macula, leading to the loss of central vision. Intravitreal injection of vascular endothelial growth factor (VEGF) inhibitors (e.g., anti-VEGF) is the standard of care for nAMD. However, nearly 50% of patients do not respond or respond poorly to the therapy. More importantly, up to 70% of nAMD patients develop macular fibrosis after 10 years of anti-VEGF therapy. The underlying mechanism of nAMD-mediated macular fibrosis is unknown although inflammation is known to play an important role in the development of abnormal macular blood vessels and its progression to fibro-vascular membrane. In this study, we measured the intraocular levels of adhesion molecule VCAM-1, ICAM-1, CD44, CD62L, and CD62P in nAMD patients with and without macular fibrosis and investigated the link between the levels of adhesion molecule and clinical features (e.g., visual improvement, retinal thickness, etc.). We further investigated the effect of VCAM-1 in macrophage function in vitro and the development of subretinal fibrosis in vivo using a two-stage laser-induced protocol.

RESULTS

The aqueous levels of ICAM-1, VCAM-1, CD44, and CD62L were significantly higher in nAMD patients compared to cataract controls. The aqueous level of VCAM-1 (but not other adhesion molecules) was significantly higher in patients with macular fibrosis than those without and the level correlated positively with the retinal thickness. VCAM-1 was highly expressed at the lesion site in the mouse model of subretinal fibrosis. Blocking VCAM-1 or its receptor VLA-4 significantly prevented macrophage infiltration and reduced subretinal fibrosis in vivo. VCAM-1 induced macrophage migration and upregulated the expression of Arg-1, Mmp12 and Il6 but down-regulated the expression of iNOS and Il1b in macrophages.

CONCLUSIONS

VCAM-1 may contribute to the development of macular fibrosis in nAMD patients by modulating macrophage functions, including migration and profibrotic polarization.

STING-Dependent Sensing of Self-DNA Driving Pyroptosis Contributes to Radiation-Induced Lung Injury

PURPOSE

Radiation therapy (RT) is indispensable for managing thoracic carcinomas. However, its application is limited by radiation-induced lung injury (RILI), one of the most common and fatal complications of thoracic RT. Nonetheless, the exact molecular mechanisms of RILI remain poorly understood.

METHODS AND MATERIALS

To elucidate the underlying mechanisms, various knockout mouse strains were subjected to 16 Gy whole-thoracic RT. RILI was assessed by quantitative real-time polymerase chain reaction, enzyme-linked immunosorbent assay, histology, western blot, immunohistochemistry, and computed tomography examination. To perform further mechanistic studies on the signaling cascade during the RILI process, pulldown, chromatin immunoprecipitation assay, and rescue assays were conducted.

RESULTS

We found that the cGAS-STING pathway was significantly upregulated after irradiation exposure in both the mouse models and clinical lung tissues. Knocking down either cGAS or STING led to attenuated inflammation and fibrosis in mouse lung tissues. NLRP3 is hardwired to the upstream DNA-sensing cGAS-STING pathway to trigger of the inflammasome and amplification of the inflammatory response. STING deficiency suppressed the expressions of the NLRP3 inflammasome and pyroptosis-pertinent components containing IL-1β, IL-18, GSDMD-N, and cleaved caspase-1. Mechanistically, interferon regulatory factor 3, the essential transcription factor downstream of cGAS-STING, promoted the pyroptosis by transcriptionally activating NLRP3. Moreover, we found that RT triggered the release of self-dsDNA in the bronchoalveolar space, which is essential for the activation of cGAS-STING and the downstream NLRP3-mediated pyroptosis. Of note, Pulmozyme, an old drug for the management of cystic fibrosis, was revealed to have the potential to mitigate RILI by degrading extracellular dsDNA and then inhibiting the cGAS-STING-NLRP3 signaling pathway.

CONCLUSIONS

These results delineated the crucial function of cGAS-STING as a key mediator of RILI and described a mechanism of pyroptosis linking cGAS-STING activation with the amplification of initial RILI. These findings indicate that the dsDNA-cGAS-STING-NLRP3 axis might be potentially amenable to therapeutic targeting for RILI.

Adipocyte- and Monocyte-Mediated Vicious Circle of Inflammation and Obesity (Review of Cellular and Molecular Mechanisms)

Monocytes play a key role in the development of metabolic syndrome, and especially obesity. Given the complex features of their development from progenitor cells, whose regulation is mediated by their interactions with bone marrow adipocytes, the importance of a detailed study of the heterogeneous composition of monocytes at the molecular and systemic levels becomes clear. Research argues for monocytes as indicators of changes in the body's metabolism and the possibility of developing therapeutic strategies to combat obesity and components of metabolic syndrome based on manipulations of the monocyte compound of the immune response. An in-depth study of the heterogeneity of bone-marrow-derived monocytes and adipocytes could provide answers to many questions about the pathogenesis of obesity and reveal their therapeutic potential.