Promotes Macrophage Activation Research Articles

Structural identification, rheological properties and immunological receptor of a complex galacturonoglucan from fruits of Schisandra chinensis (Turcz.) Baill

A complex heteropolysaccharide SCP-2 named schisanan B (Mw = 1.005 × 105 g/mol) was obtained from water extracts of Schisandra chinensis fruits, and its planar structure was finally deduced as a galacturonoglucan by a combination of monosaccharide compositions, methylation analysis, partial acid hydrolysis, enzymatic hydrolysis and 1D/2D-nuclear magnetic resonance spectroscopy. The conformation of SCP-2 exhibited a globular shape with branching in ammonium formate aqueous solutions. The rheological properties of SCP-2 were investigated on concentrations, temperature, pH and salts. The in vitro immunomodulatory activity assay demonstrated that SCP-2 significantly enhanced the production of nitric oxide (NO) and stimulated the secretion of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) in macrophages. Through a combination of high-resolution live-cell imaging, surface plasmon resonance, and molecular docking techniques, SCP-2 exhibited a strong binding affinity with the Toll-like receptor 4 (TLR4). Moreover, western blot analysis revealed that SCP-2 effectively induced downstream signaling proteins associated with TLR4 activation, thereby promoting macrophage activation. The evidence strongly indicates that TLR4 functions as a membrane protein target in the activation of macrophages and immune regulation induced by SCP-2.

MiR-331-depleted exosomes derived from injured endometrial epithelial cells promote macrophage activation during endometritis

Exosomes are natural carriers of biological macromolecules that are involved in the pathogenesis of a wide variety of inflammatory diseases. The purpose of this study was to investigate the role of exosomes derived from injured endometrial epithelial cells (EECs) in the development of endometritis. We isolated exosomes derived from LPS-injured EECs and identified these exosomes as proinflammatory mediators that can be internalized by macrophages and thus induce proinflammatory macrophage activation. We further found that miR-331 expression was sharply downregulated in exosomes derived from LPS-injured EECs and that macrophages treated with these exosomes also presented a lower level of miR-331. Importantly, the pathogenic role of exosomal miR-331 in promoting endometrial inflammation was revealed by the ability of adoptively transferred EECs-derived exosomes to cause macrophage activation, and this was reversed by miR-331 overexpression. Mechanistically, overexpression of miR-331 in macrophages mitigated NF-κB p65 phosphorylation by inhibiting the Notch1/IKKα pathway, which in turn curbed macrophage activation. In vivo assays further unveiled that miR-331 expression is negatively correlated with proinflammatory macrophage activation and that miR-331 upregulation markedly slowed disease progression in mice with endometritis. The exosome/miR-331/Notch1 axis plays a critical pathological role in endometrial inflammation, representing a new therapeutic target for endometritis.

LncRNA MAAMT facilitates macrophage recruitment and proinflammatory activation and exacerbates autoimmune myocarditis through the SRSF1/NF-κB axis

Long non-coding RNAs (lncRNAs) have been implicated in dilated cardiomyopathy (DCM). However, the biological functions and regulatory mechanisms of lncRNAs in DCM remain elusive. Using a mouse model of experimental autoimmune myocarditis (EAM) to mimic DCM, we successfully constructed a dynamic lncRNA expression library for EAM by lncRNA microarray and found that the expression of a macrophage-enriched lncRNA, MAAMT, was significantly increased in the myocardial tissue of mice at the acute stage of EAM. Functionally, MAAMT knockdown alleviated the recruitment and proinflammatory activation of macrophages in the heart, spleen, and peripheral blood of mice at the acute stage of EAM, reduced myocardial inflammation and injury, and eventually reversed ventricular remodelling and improved cardiac function in mice at the chronic stage of EAM. Mechanistically, we identified serine/arginine-rich splicing factor 1 (SRSF1) as an MAAMT-interacting protein in macrophages using RNA pull-down assays coupled with mass spectrometry. MAAMT knockdown attenuated the ubiquitination-mediated degradation of SRSF1, increased the protein expression of SRSF1, and restrained the activation of the NF-κB pathway in macrophages, thereby inhibiting the proinflammatory activation of macrophages. Collectively, our results demonstrate that MAAMT is a key proinflammatory regulator of myocarditis that promotes macrophage activation through the SRSF1-NF-κB axis, providing a new insight into early effective treatment strategies for DCM.

BDNF-VGF Pathway Aggravates Incision Induced Acute Postoperative Pain via Upregulating the Neuroinflammation in Dorsal Root Ganglia.

Approximately one-third of postoperative patients are troubled by postoperative pain. Effective treatments are still lacking. The aim of this study is to investigate the role of brain-derived neurotrophic factor (BDNF)-VGF (non-acronymic) in dorsal root ganglia (DRG) in postoperative pain.Pain behaviors were assessed through measurements of paw withdrawal threshold (PWT) and paw withdrawal latency (PWL). Transcriptome analysis was conducted to identify potential targets associated with postoperative pain. Western blotting, immunofluorescence, and ELISA were employed to further detect macrophage activationas well as the expression of BDNF, VGF, TNF-α, IL-1β, and IL-6.Results showed that plantar incision induced both mechanical and thermal hyperalgesia. Transcriptome analysis suggested that plantar incision caused upregulation of BDNF and VGF. The expressions of BDNF and VGF were upregulated in isolectin B4-positive (IB4+) and calcitonin gene-related peptide-positive (CGRP+) neurons, rather than neurofilament 200-positive (NF200+) neurons. The activation of BDNF-VGF pathway upregulated expression of IL-6, TNF-α, and IL-1β and promoted the activation of macrophages.In conclusion, BDNF-VGF pathway aggravates acute postoperative pain by promoting macrophage activation and pro-inflammatory cytokine production, which may provide a new target for the treatment of postoperative pain.

Serum interleukin-34 levels in dermatomyositis: a potential biomarker for anti-MDA5-antibody-associated interstitial lung disease.

Interleukin (IL)-34 is a hematopoietic cytokine that promotes macrophage activation. Macrophage activation in interstitial lung disease (ILD) in patients with dermatomyositis (DM), especially in those with anti-melanoma differentiation-associated gene 5 (MDA5) antibody suggests the involvement of IL-34 in the disease. However, the association between IL-34 and DM is unknown. In this study, we aimed to determine serum IL-34 levels in DM patients and evaluate their association with DM-ILD. We measured serum IL-34 levels in 56 DM patients and 14 age- and sex- matched healthy controls by enzyme-linked immunosorbent assay, and examined their correlation with clinical parameters. In addition, pre- and post-treatment serum IL-34 levels were examined using serum samples from 7 anti-MDA5 antibody-positive DM patients. Serum IL-34 levels were significantly elevated in DM patients, especially in those with anti-MDA5 antibody, compared with healthy controls. In anti-MDA5-antibody-positive DM patients, serum IL-34 levels positively correlated with serum levels of ferritin and anti-MDA5 antibody, which are known biomarkers for rapidly progressive (RP)-ILD. Following combined immunosuppressive therapy, serum IL-34 levels decreased along with ferritin and anti-MDA5 antibody. These data suggest that IL-34 may be involved in the development of RP-ILD in anti-MDA5 antibody-positive DM. Serum IL-34 levels can serve as a potential biomarker for RP-ILD in this clinical entity.

MS4A6D Promotes carrageenan-induced footpad swelling in mice through enhancing macrophages-derived inflammation

Our previous work has demonstrated that the tetraspan MS4A6D interacts with MHC-II to be a complex that promotes macrophage activation (Mol Immunol. 2023; 160: 121–132), however, the exact role of MS4A6D in controlling macrophage-derived inflammation is still poorly understood. Here, we showed that Ms4a6d-deficient (Ms4a6d-/-) mice manifested a lower level of footpad swelling induced by subcutaneous injection of 100 μL of 1% Carrageenan (CGN, w/v) plus CaCl2 (50 mM), a phenomenon that is similar to Nlrp3-/-, Casp-1-/-, and Ilr1-/- mice. Mechanistically, F4/80+ macrophages infiltrated in the footpad tissues of the Ms4A6d-/- mice was significantly lower than that of the WT littermates, leading to dramatically lower levels of proIL-1β in vivo. Moreover, macrophages from Ms4a6d-/- mice also showed a dramatical reduction of Il-1β secretion following NLRP3 inflammsome activation in vitro. Interestingly, both Ms4a6dC237G mutant (Interruption of MS4A6D homodimerization) and Ms4a6dY241G mutant (deletion of heITAM motif) mice also significantly inhibited CGN-induced footpad swelling due to lower levels of Il-1β secretion in vivo. Collectively, MS4A6D aggravates CGN-induced footpad swelling in mice by enhancing NLRP3 inflammasome in macrophages and inducing the release of IL-1β, indicating that MS4A6D promotes the progression of acute inflammation.

Obesity-induced downregulation of miR-192 exacerbates lipopolysaccharide-induced acute lung injury by promoting macrophage activation

BackgroundMacrophage activation may play a crucial role in the increased susceptibility of obese individuals to acute lung injury (ALI). Dysregulation of miRNA, which is involved in various inflammatory diseases, is often observed in obesity. This study aimed to investigate the role of miR-192 in lipopolysaccharide (LPS)-induced ALI in obese mice and its mechanism of dysregulation in obesity.MethodsHuman lung tissues were obtained from obese patients (BMI ≥ 30.0 kg/m2) and control patients (BMI 18.5–24.9 kg/m2). An obese mouse model was established by feeding a high-fat diet (HFD), followed by intratracheal instillation of LPS to induce ALI. Pulmonary macrophages of obese mice were depleted through intratracheal instillation of clodronate liposomes. The expression of miR-192 was examined in lung tissues, primary alveolar macrophages (AMs), and the mouse alveolar macrophage cell line (MH-S) using RT-qPCR. m6A quantification and RIP assays helped determine the cause of miR-192 dysregulation. miR-192 agomir and antagomir were used to investigate its function in mice and MH-S cells. Bioinformatics and dual-luciferase reporter gene assays were used to explore the downstream targets of miR-192.ResultsIn obese mice, depletion of macrophages significantly alleviated lung tissue inflammation and injury, regardless of LPS challenge. miR-192 expression in lung tissues and alveolar macrophages was diminished during obesity and further decreased with LPS stimulation. Obesity-induced overexpression of FTO decreased the m6A modification of pri-miR-192, inhibiting the generation of miR-192. In vitro, inhibition of miR-192 enhanced LPS-induced polarization of M1 macrophages and activation of the AKT/ NF-κB inflammatory pathway, while overexpression of miR-192 suppressed these reactions. BIG1 was confirmed as a target gene of miR-192, and its overexpression offset the protective effects of miR-192. In vivo, when miR-192 was overexpressed in obese mice, the activation of pulmonary macrophages and the extent of lung injury were significantly improved upon LPS challenge.ConclusionsOur study indicates that obesity-induced downregulation of miR-192 expression exacerbates LPS-induced ALI by promoting macrophage activation. Targeting macrophages and miR-192 may provide new therapeutic avenues for obesity-associated ALI.Graphical

Unveiling the immunomodulatory effect of the novel probiotic Akkermansia muciniphila and its protective effect in vitro

Akkermansia muciniphila, a bacterium found in the human microbiota, has gained interest due to its potential health benefits. Previous studies have linked its absence to inflammatory disorders, while also suggesting its role in maintaining a healthy gut barrier. However, there is limited information on its specific effects on the immune system. Therefore, the aim of this research was to analyze the in vitro response triggered by A. muciniphila employing RAW 264.7 macrophages. The study focused on investigating the production of cytokines and nitric oxide, along with evaluating the expression of inflammatory surface cellular markers. Additionally, we assessed its potential to protect against intestinal infections, using Salmonella enterica serovar Enteritidis as a model. Our findings reveal a modulation effect of A. muciniphila with pro-inflammatory features, including the release of pro-inflammatory cytokines and upregulation of CD40 and CD80 surface markers, in contrast with previous reported data. Importantly, A. muciniphila could protect against Salmonella infection by promoting macrophage activation, appearing as a promising probiotic candidate for the control of intestinal infections.

Macrophages Promote Atherosclerosis Development by Inhibiting CD8T Cell Apoptosis.

Atherosclerosis is an inflammatory cardiovascular disease. However, whether the association of immune cells in plaques promotes the progression of this disease has not yet been completely elucidated. Thus, this study aimed to investigate the relationship between C1q+ macrophages and CD8T cells through scRNA-seq data reanalysis, quantitative real-time PCR, and flow cytometry. Chromatin immunoprecipitation-quantitative polymerase chain reaction, western blot, and antibody-blocking experiments were performed to investigate the role of macrophage-CD8T interaction in atherosclerosis. An atherosclerotic mouse model was developed to confirm our findings. Mechanistically, Spi1 expression induced by granulocyte-macrophage colony-stimulating factor promoted C1q expression in the macrophages. Moreover, C1q+ macrophages suppressed CD8T cell apoptosis by upregulating Slc7a7 expression to enhance the L-arginine uptake of CD8T cells. CD8T-derived interferon-γ promoted macrophage activation to induce atherosclerosis. Blockade of the C1q-C1qbp axis attenuated atherosclerosis. In conclusion, macrophages interacting with CD8T promote atherosclerosis development via the C1q-C1qbp axis.

The role of proprotein convertase subtilisin/kexin 9 (PCSK9) in macrophage activation: a focus on its LDL receptor-independent mechanisms.

Recent clinical trials demonstrated that proprotein convertase subtilisin/kexin 9 (PCSK9) inhibitors reduce cardiovascular events without affecting systemic inflammation in the patients with coronary artery disease, as determined by high sensitivity C-reactive protein (CRP) levels. However, its pro-inflammatory effects in cardiovascular disease in humans and experimental animals beyond the traditional cholesterol receptor-dependent lipid metabolism have also called attention of the scientific community. PCSK9 may target receptors associated with inflammation other than the low-density lipoprotein receptor (LDLR) and members of the LDLR family. Accumulating evidence suggests that PCSK9 promotes macrophage activation not only via lipid-dependent mechanisms, but also lipid-independent and LDLR-dependent or -independent mechanisms. In addition to dyslipidemia, PCSK9 may thus be a potential therapeutic target for various pro-inflammatory diseases.

Phosphorylation of RGS16 at Tyr168 promote HBeAg-mediated macrophage activation by ERK pathway to accelerate liver injury.

Liver injury is closely associated with macrophage activation following HBV infection. Our previous study showed that only HBeAg, but not HBsAg and HBcAg, stably enhances inflammatory cytokine production in macrophages. And we also indicated that HBeAg could induce macrophage activation via TLR2 and thus aggravate the progression of liver fibrosis. However, the specific molecular mechanism of HBeAg in macrophage activation is not clear. We screened significantly overexpressed RGS16 from RNASeq results of HBeAg-stimulated macrophages and validated them with cellular assays, GSE83148 microarray dataset, and in clinical samples. Meanwhile, small interference, plasmid, and lentivirus transfection assays were used to establish cell models for knockdown and overexpression of RGS16, and q-PCR, ELISA, Transwell, and CCK-8 assays were used to analyze the role of RGS16 in HBeAg-induced macrophage activation. In addition, the upstream and downstream mechanisms of RGS16 in HBeAg-treated macrophage activation were explored using inhibitors, phostag gels, and RGS16 phosphorylation mutant plasmids. Finally, the effect of RGS16 on hepatic inflammation in murine tissues was evaluated by H&E staining, liver enzyme assay and immunofluorescence. RGS16 was significantly upregulated in HBeAg-induced macrophage activation, and its expression was enhanced with increasing HBeAg content and treatment time. Functional experiments showed that overexpression of RGS16 promoted the production of inflammatory factors TNF-α and IL-6 and boosted macrophage proliferation and migration, while knockdown of RGS16 exhibited the opposite effect. Mechanistically, we discovered that RGS16 is regulated by the TLR2/P38/STAT5 signaling pathway. Meanwhile, RGS16 enhanced ERK phosphorylation via its own Tyr168 phosphorylation to contribute to macrophage activation, thereby accelerating liver injury. Finally, in mice, overexpression of RGS16 markedly strengthened liver inflammation. HBeAg upregulates RGS16 expression through the TLR2-P38-STAT5 axis, and the upregulated expression of RGS16 enhances macrophage activation and accelerates liver injury by promoting ERK phosphorylation. In this process, phosphorylation of Tyr168 is necessary for RGS16 to function. KEY MESSAGES: RGS16 boosted HBeAg-induced macrophage inflammation, proliferation, and migration. Tyr168 phosphorylation of RGS16 affected by ERK promoted macrophage activation. HBeAg upregulated the expression of RGS16 through TLR2/P38/STAT5 signal pathway. RGS16 promoted liver injury by regulating macrophage functions in mouse model.

Flagellar hook protein FlgE promotes macrophage activation and atherosclerosis by targeting ATP5B

Background and aimsPseudomonas aeruginosa (P. aeruginosa) infections are strongly linked to the development of cardiovascular disease and atherosclerosis; however, the underlying mechanisms remain unclear. We previously confirmed that the flagellar hook protein FlgE in P. aeruginosa has immunostimulatory effects. This study investigated the effects and mechanisms of action of FlgE on atherogenesis. MethodsApoE−/− mice were intravenously challenged with FlgE or FlgEM recombinant proteins for eight weeks. A murine model of chronic lung colonization was established using beads containing either mutable- or wild-type bacteria. Aortic sinus sections were stained to assess atherosclerosis progression. THP-1 macrophages exposed to FlgE or FlgEM were evaluated for their effects on lipid uptake and inflammation in vitro. Western blotting and pull-down assays were used to identify the binding proteins and signaling pathways involved, and specific blocking experiments were performed to confirm these effects. ResultsFlgE accelerated atherosclerosis progression by triggering lipid deposition and inflammatory responses in high-fat diet (HFD)-fed ApoE−/− mice. In comparison to infection with wild-type PAO1, infection with PAO1/flgEΔBmF resulted in reduced atherosclerosis. Mechanistic analysis indicated that FlgE exacerbated lipoprotein uptake and foam cell formation by upregulating SR-A1 expression. Moreover, FlgE activated NF-κB and MAPK signaling, which subsequently led to inflammatory responses in THP-1-derived macrophages. Pull-down assays revealed that FlgE directly interacted with ATP5B, whereas blocking ATP5B attenuated FlgE-induced responses in macrophages. ConclusionsFlgE induces macrophage lipid uptake and pro-inflammatory responses mediated by ATP5B/NF-kB/AP-1 signaling, which eventually results in atherosclerosis. These findings support the development of therapeutic strategies for P. aeruginosa infection-induced atherosclerosis.

Construction of quercetin-fucoidan nanoparticles and their application in cancer chemo-immunotherapy treatment

Fucoidan (FU), a natural marine polysaccharide, is an immunomodulator with great potential in tumor immunotherapy. In this work, a FU encapsulated nanoparticle named QU@FU-TS was developed, which contained the anticancer phytochemical quercetin (QU) and had the potential for cancer chemo-immunotherapy. QU@FU-TS were constructed through molecular self-assembly using green material tea saponin (TS) as the linking molecule. The molecular dynamics (MD) simulation showed that QU was bound to the hydrophobic tail of TS. At the same time, FU spontaneously assembled with the hydrophilic head of TS to form the outer layer of the QU@FU-TS. The molecular interactions between QU and TS were mainly π-stacking and hydrogen bonds. The bonding of FU and TS was maintained through the formation of multiple hydrogen bonds between the sulfate ester group and the hydroxy group. The inhibitory effects of QU@FU-TS on A549 cell proliferation were more potent than that by free QU. The antitumor activity of QU@FU-TS was mediated through various mechanisms, including the induction of oxidative stress, blocking cell cycle progression, and promoting cell apoptosis. Moreover, QU@FU-TS has been demonstrated to impede the proliferation and migration of cancer cells in vivo. The expression levels of macrophage surface markers increased under the treatment of QU@FU-TS, suggesting the potential of QU@FU-TS to serve as an immunotherapeutic agent by promoting macrophage activation.

Augmented CD36 Stimulation by Fatty Acids Promotes Macrophage Activation and Endothelial Injury in ANCA-Associated Vasculitis

Augmented CD36 Stimulation by Fatty Acids Promotes Macrophage Activation and Endothelial Injury in ANCA-Associated Vasculitis

CircUBXN7 promotes macrophage infiltration and renal fibrosis associated with the IGF2BP2-dependent SP1 mRNA stability in diabetic kidney disease.

Inflammatory cell infiltration is a novel hallmark of diabetic kidney disease (DKD), in part, by activated macrophages. Macrophage-to-tubular epithelial cell communication may play an important role in renal fibrosis. Circular RNAs (circRNAs) have been reported in the pathogenesis of various human diseases involving macrophages activation, including DKD. However, the exact mechanism of circRNAs in macrophage infiltration and renal fibrosis of DKD remains obscure. In our study, a novel circRNA circUBXN7 was identified in DKD patients using microarray. The function of circUBXN7 in vitro and in vivo was investigated by qRT-PCR, western blot, and immunofluorescence. Finally, a dual-luciferase reporter assay, ChIP, RNA pull-down, RNA immunoprecipitation and rescue experiments were performed to investigate the mechanism of circUBXN7. We demonstrated that the expression of circUBXN7 was significantly upregulated in the plasma of DKD patients and correlated with renal function, which might serve as an independent biomarker for DKD patients. According to investigations, ectopic expression of circUBXN7 promoted macrophage activation, EMT and fibrosis in vitro, and increased macrophage infiltration, EMT, fibrosis and proteinuria in vivo. Mechanistically, circUBXN7 was transcriptionally upregulated by transcription factor SP1 and could reciprocally promote SP1 mRNA stability and activation via directly binding to the m6A-reader IGF2BP2 in DKD. CircUBXN7 is highly expressed in DKD patients may provide the potential biomarker and therapeutic target for DKD.

Lipotoxicity-polarised macrophage-derived exosomes regulate mitochondrial fitness through Miro1-mediated mitophagy inhibition and contribute to type 2 diabetes development in mice.

Insulin resistance is a major pathophysiological defect in type 2 diabetes and obesity. Numerous experimental and clinical studies have provided evidence that sustained lipotoxicity-induced mitophagy deficiency can exacerbate insulin resistance, leading to a vicious cycle between mitophagy dysfunction and insulin resistance, and thereby the onset of type 2 diabetes. Emerging evidence suggests that exosomes (Exos) from M2 macrophages play an essential role in modulating metabolic homeostasis. However, how macrophages are affected by lipotoxicity and the role of lipotoxicity in promoting macrophage activation to the M1 state have not been determined. The objective of this study was to determine whether M1 macrophage-derived Exos polarised by lipopolysaccharide (LPS) + palmitic acid (PA)-induced lipotoxicity contribute to metabolic homeostasis and impact the development of insulin resistance in type 2 diabetes. Lipotoxicity-polarised macrophage-derived M1 Exos were isolated from bone marrow (C57BL/6J mouse)-derived macrophages treated with LPS+PA. Exos were characterised by transmission electron microscopy, nanoparticle tracking analysis and western blotting. Flow cytometry, H&E staining, quantitative real-time PCR, immunofluorescence, glucose uptake and output assays, confocal microscopy imaging, western blotting, GTTs and ITTs were conducted to investigate tissue inflammation, mitochondrial function and insulin resistance in vitro and in vivo. The roles of miR-27-3p and its target gene Miro1 (also known as Rhot1, encoding mitochondrial rho GTPase 1) and relevant pathways were predicted and assessed in vitro and in vivo using specific miRNA mimic, miRNA inhibitor, miRNA antagomir and siRNA. miR-27-3p was highly expressed in M1 Exos and functioned as a Miro1-inactivating miRNA through the miR-27-3p-Miro1 axis, leading to mitochondria fission rather than fusion as well as mitophagy impairment, resulting in NOD-like receptor 3 inflammatory activation and development of insulin resistance both in vivo and in vitro. Inactivation of miR-27-3p induced by M1 Exos prevented type 2 diabetes development in high-fat-diet-fed mice. These findings suggest that the miR-27-3p-Miro1 axis, as a novel regulatory mechanism for mitophagy, could be considered as a new therapeutic target for lipotoxicity-related type 2 diabetes disease development.

Targeting sphingosine 1-phosphate receptor 3 inhibits T-cell exhaustion and regulates recruitment of proinflammatory macrophages to improve antitumor efficacy of CAR-T cells against solid tumor

BackgroundsChimeric antigen receptor (CAR)-modified T cells (CAR-T) are limited in solid tumors due to the hostile tumor microenvironment (TME). Combination therapy could be a promising approach to overcome this obstacle....

LPS inhibits TRIM65 expression in macrophages and C57BL/6J mouse by activating the ERK1/2 signaling pathway.

Activated macrophages serve a key role in various inflammatory diseases, such as atherosclerosis and septic shock. Tripartite motif-containing protein 65 (TRIM65) has been previously reported to participate in tumor progression and lung inflammation. However, the molecular mechanisms that controls its expression under inflammatory conditions and its consequences in activated macrophages remain poorly understood. The present study first collected the tissues of C57BL/6J mice, smooth muscle cells, macrophages and endothelial cells to determine the expression and distribution of TRIM65 by reverse transcription-quantitative (RT-q) PCR and western blotting. Mouse and human macrophages were treated with LPS and C57BL/6J mice were intraperitoneally injected with LPS followed by isolation of spleen, lung, aorta and bone marrow. Following treatment, TRIM65 mRNA and protein level was examined by RT-qPCR and western blotting. The results showed that TRIM65 was highly expressed in organs of the immune system, such as the spleen, lymph node and thymus, but lowly expressed in heart, liver, brain and kidneys. TRIM65 was also highly expressed in macrophages and endothelial cells. TRIM65 mRNA and protein expression levels were found to be decreased in LPS-treated macrophages in vitro and in tissues isolated from C57BL/6J mice intraperitoneally injected with LPS in vivo. In addition, to identify the signaling pathways by which LPS regulates TRIM65 expression, inhibitors of MAPK and Akt signaling pathways were used to treat macrophages followed by examination the expression of TRIM65 by western blotting. The results demonstrated that LPS-inhibited TRIM65 expression was blocked by treatment with the ERK1/2 inhibitor U0126. Moreover, the RT-qPCR results showed that TRIM65 knockout potentiated LPS-induced expression of inflammatory cytokines in macrophages. Taken together, data from the present study suggest that LPS decreased TRIM65 expression in macrophages and C57BL/6J mouse by activating the ERK1/2 signaling pathway, whilst TRIM65 knockout promoted macrophage activation. This information may facilitate the development of potential therapeutic strategies for the prevention and treatment of inflammatory diseases, such as atherosclerosis.

ADAR1 promotes systemic sclerosis via modulating classic macrophage activation.

As a multisystem autoimmune disorder disease, systemic sclerosis (SSc) is characterized by inflammation and fibrosis in the skin and other internal organs. However, mechanisms underlying the inflammatory response that drives the development of SSc remain largely unknown. ADAR1 heterozygous knockout (AD1+/-) mice and myeloid-specific ADAR1 knockout mice were used to determine the function of ADAR1 in SSc. Histopathological analyses and western blot confirmed the role of ADAR1 in bleomycin-induced increased skin and lung fibrosis. In this study, we discover that adenosine deaminase acting on RNA (ADAR1), a deaminase converting adenosine to inosine (i.e., RNA editing) in RNA, is abundantly expressed in macrophages in the early stage of bleomycin-induced SSc. Importantly, ADAR1 is essential for SSc formation and indispensable for classical macrophage activation because ADAR1 deficiency in macrophages significantly ameliorates skin and lung sclerosis and inhibits the expression of inflammation mediator inducible NO synthase (iNOS) and IL-1β in macrophages. Mechanistically, deletion of ADAR1 blocks macrophage activation through diminishing NF-κB signaling. Our studies reveal that ADAR1 promotes macrophage activation in the onset of SSc. Thus, targeting ADAR1 could be a potential novel therapeutic strategy for treating sclerosis formation.

Meet the First Authors.

Meet the First Authors.