Mitochondrial electron transport chain in macrophage reprogramming: Potential role in antibacterial immune response.

Macrophages restrain microbial infection and reinstate tissue homeostasis. The mitochondria govern macrophage metabolism and serve as pivot in innate immunity, thus acting as immunometabolic regulon. Metabolic pathways produce electron flows that end up in mitochondrial electron transport chain (mtETC), made of super-complexes regulating multitude of molecular and biochemical processes. Cell-intrinsic and extrinsic factors influence mtETC structure and function, impacting several aspects of macrophage immunity. These factors provide the macrophages with alternate fuel sources and metabolites, critical to gain functional competence and overcoming pathogenic stress. Mitochondrial reactive oxygen species (mtROS) and oxidative phosphorylation (OXPHOS) generated through the mtETC are important innate immune attributes, which help macrophages in mounting antibacterial responses. Recent studies have demonstrated the role of mtETC in governing mitochondrial dynamics and macrophage polarization (M1/M2). M1 macrophages are important for containing bacterial pathogens and M2 macrophages promote tissue repair and wound healing. Thus, mitochondrial bioenergetics and metabolism are intimately coupled with innate immunity. In this review, we have addressed mtETC function as innate rheostats that regulate macrophage reprogramming and innate immune responses. Advancement in this field encourages further exploration and provides potential novel macrophage-based therapeutic targets to control unsolicited inflammation.

Gut microbially produced tryptophan metabolite melatonin ameliorates osteoporosis via modulating SCFA and TMAO metabolism.

Osteoporosis (OP) is a severe global health issue that has significant implications for productivity and human lifespan. Gut microbiota dysbiosis has been demonstrated to be closely associated with OP progression. Melatonin (MLT) is an important endogenous hormone that modulates bone metabolism, maintains bone homeostasis, and improves OP progression. Multiple studies indicated that MLT participates in the regulation of intestinal microbiota and gut barrier function. However, the promising effects of gut microbiota-derived MLT in OP remain unclear. Here, we found that OP resulted in intestinal tryptophan disorder and decreased the production of gut microbiota-derived MLT, while administration with MLT could mitigate OP-related clinical symptoms and reverse gut microbiota dysbiosis, including the diversity of intestinal microbiota, the relative abundance of many probiotics such as Allobaculum and Parasutterella, and metabolic function of intestinal flora such as amino acid metabolism, nucleotide metabolism, and energy metabolism. Notably, MLT significantly increased the production of short-chain fatty acids and decreased trimethylamine N-oxide-related metabolites. Importantly, MLT could modulate the dynamic balance of M1/M2 macrophages, reduce the serum levels of pro-inflammatory cytokines, and restore gut-barrier function. Taken together, our results highlighted the important roles of gut microbially derived MLT in OP progression via the "gut-bone" axis associated with SCFA metabolism, which may provide novel insight into the development of MLT as a promising drug for treating OP.

Favipiravir ameliorates bleomycin-induced pulmonary fibrosis by reprogramming M1/M2 macrophage polarization.

Corona Virus Disease 2019 (COVID-19) is an infectious disease that seriously endangers human life and health. The pathological anatomy results of patients who died of the COVID-19 showed that there was an excessive inflammatory response in the lungs. It is also known that most of the COVID-19 infected patients will cause different degrees of lung damage after infection, and may have pulmonary fibrosis remaining after cure. Macrophages are a type of immune cell population with pluripotency and plasticity. In the early and late stages of infection, the dynamic changes of the balance and function of M1/M2 alveolar macrophages have a significant impact on the inflammatory response of the lungs. In the early stage of pulmonary fibrosis inflammation, the increase in the proportion of M1 type is beneficial to clear pathogenic microorganisms and promote the progress of inflammation; in the later stage of fibrosis, the increase in the number of M2 type macrophages can inhibit the inflammatory response and promote the degradation of fibrosis. As a potential treatment drug for new coronavirus pneumonia, favipiravir is in the process of continuously carried out relevant clinical trials. This study aims to discuss whether the antiviral drug favipiravir can suppress inflammation and immune response by regulating the M1/M2 type of macrophages, thereby alleviating fibrosis. We established a bleomycin-induced pulmonary fibrosis model, using IL-4/13 and LPS/IFN-γ cell stimulating factor to induce macrophage M1 and M2 polarization models, respectively. Our study shows that favipiravir exerts anti-fibrotic effects mainly by reprogramming M1/M2 macrophages polarization, that is, enhancing the expression of anti-fibrotic M1 type, reducing the expression of M2 type pro-fibrotic factors and reprogramming it to anti-fibrotic phenotype. Aspects of pharmacological mechanisms, favipiravir inhibits the activation of JAK2-STAT6 and JAK2-PI3K-AKT signaling by targeting JAK2 protein, thereby inhibiting pro-fibrotic M2 macrophages polarization and M2-induced myofibroblast activation. In summary, favipiravir can reduce the progression of pulmonary fibrosis, we hope to provide a certain reference for the treatment of pulmonary fibrosis.

A hidden dilemma; post COVID-19 first detection of Varicella zoster M4 genotype from Pakistan.

OBJECTIVES: During the COVID-19 pandemic, the risk of childhood infectious diseases was increased. Post-COVID-19 escalation of chickenpox cases, becoming an emerging public health concern. Thus, the study was designed to compare chickenpox prevalence and Varicella zoster virus (VZV) genotypes circulating before, during, and post-COVID-19 in Pakistan. METHODS: A total of 267 lesion specimens collected from tertiary care hospitals, and chickenpox outbreaks from Pakistan were analysed by a two-amplicon approach with phylogenetic analysis. RESULTS: Among suspected cases, overall 178/267 were VZV positive. Majority (84.2 %; 150/178) cases were of post-COVID-19 pandemic time. Small outbreaks occurred soon after COVID-19 in Rawalpindi and Islamabad (Pakistan), 40 positive cases out of 178 cases were outbreak cases. There was first time detection of the M4 genotype, which was significantly associated with disease severity (p = 0.0006) and post-COVID-19 chickenpox outbreaks in 2021 (77.9 %; 46/59; p < 0.00001). However, in pre-COVID-19 only M2 genotype was detected. The M2 prevalence varied from 2019 (100 %; 19/19) to 2022 (3.2 %; 3/91). However, the most prevalent strain of 2022 belonged to the M1 genotype (64.8 %; 59/91). CONCLUSION: A significant rise in chickenpox cases detected soon after COVID-19 in Pakistan, and oscillation of different VZV genotypes with first time detection of M4 genotype is an alarming situation. This demands further detailed genotypic studies on transmission dynamics of a rare M4 with other genotypes to protect the local population and restrict spread in other regions.

A comprehensive review of phytochemicals targeting macrophages for the regulation of colorectal cancer progression.

BACKGROUND: Phytochemicals are natural compounds derived from plants, and are now at the forefront of anti-cancer research. Macrophage immunotherapy plays a crucial role in the treatment of colorectal cancer (CRC). In the context of colorectal cancer, which remains highly prevalent and difficult to treat, it is of research value to explore the potential mechanisms and efficacy of phytochemicals targeting macrophages for CRC treatment. PURPOSE: The aim of this study was to gain insight into the role of phytochemical-macrophage interactions in regulating CRC and to provide a theoretical basis for the development of new therapeutic strategies in the future. STUDY DESIGN: This review discusses the potential immune mechanisms of phytochemicals for the treatment of CRC by summarizing research of phytochemicals targeting macrophages. METHODS: We reviewed the PubMed, EMBASE, Web of Science and CNKI databases from their initial establishment to July 2023 to classify and summaries phytochemicals according to their mechanism of action in targeting macrophages. RESULTS: The results of the literature review suggest that phytochemicals interfere with CRC development by affecting macrophages through four main mechanisms. Firstly, they modulate the production of cytotoxic substances, such as NO and ROS, by macrophages to exert anticancer effects. Secondly, phytochemicals polarize macrophages towards the M1 phenotype, inhibit M2 polarisation and enhance the anti-tumour immune responses. Thirdly, they enhance the secretion of macrophage-derived cytokines and alter the tumour microenvironment, thereby inhibiting tumor growth. Finally, they activate the immune response by targeting macrophages, triggering the recruitment of other immune cells, thereby enhancing the immune killing effect and exerting anti-tumor effects. These findings highlight phytochemicals as potential therapeutic strategies to intervene in colorectal cancer development by modulating macrophage activity, providing a strong theoretical basis for future clinical applications. CONCLUSION: Phytochemicals exhibit potential anti-tumour effects by modulating macrophage activity and intervening in the colorectal cancer microenvironment by multiple mechanisms.

Nrdp1-mediated Macrophage Phenotypic Regulation Promotes Functional Recovery in Mice with Mild Neurological Impairment after Intracerebral Hemorrhage.

Neuregulin receptor degradation protein 1 (Nrdp1) is a ring finger E3 ubiquitin ligase involved in some inflammation through ubiquitination, including macrophage polarization following cerebral hemorrhage. However, there is limited understanding regarding the mechanisms through which Nrdp1 modulates macrophage polarization and the potential impact of this modulation on neurological function. Using stereotactic injection and adenoviral transfection techniques, the corresponding animal models were constructed through injecting adenovirus, saline, or blood into the mouse striatum at different periods of time in this research. The alteration in the ratio of various M1/M2 phenotype-associated markers (e.g., CD86, CD206, IL-6, IL-10, etc.) was evaluated through immunohistochemistry, immunofluorescence, western blotting, and elisa assays. Additionally, neurological function scores and behavioral tests were utilized to evaluate changes in neurological function in mice after cerebral hemorrhage. Our results show that overexpression of Nrdp1 promotes the expression of a variety of M2 macrophage-associated markers and enhance transcriptional activity of arginase-1 (Arg1) protein through ubiquitination for early regulation M2 macrophage polarization. Additionally, Nrdp1 promotes hematoma absorption, increases IL-10 expression, inhibits inducible nitric oxide synthase (iNOS), IL-6, and TNF-α production, alleviates neurological impairment and brain edema, and accelerates functional recovery. These findings suggest that modulating macrophage polarization through Nrdp1 could be a therapeutic strategy for neurofunctional impairment in cerebral hemorrhage.

Tolerogenic probiotics Lactobacillus delbrueckii and Lactobacillus rhamnosus promote anti-inflammatory profile of macrophages-derived monocytes of newly diagnosed patients with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is known as an autoimmune disorder that is characterized by the breakdown of self-tolerance, resulting in disease onset and progression. Macrophages have been implicated as a factor in the development of SLE through faulty phagocytosis of dead cells or an imbalanced M1/M2 ratio. The study aimed to investigate the immunomodulatory effects of Lactobacillus delbrueckii and Lactobacillus rhamnosus on M1 and M2 macrophages in new case lupus patients. For this purpose, blood monocytes were collected from lupus patients and healthy people and were cultured for 5 days to produce macrophages. For 48 h, the macrophages were then cocultured with either probiotics or lipopolysaccharides (LPS). Flow cytometry and real-time polymerase chain reaction were then used to analyze the expression of cluster of differentiation (CD) 14, CD80, and human leukocyte antigen - DR (HLADR) markers, as well as cytokine expression (interleukin [IL]1-ß, IL-12, tumor necrosis factor α [TNF-α], IL-10, and transforming growth factor beta [TGF-ß]). The results indicated three distinct macrophage populations, M0, M1, and M2. In both control and patient-derived macrophage-derived monocytes (MDMs), the probiotic groups showed a decrease in CD14, CD80, and HLADR expression compared to the LPS group. This decrease was particularly evident in M0 and M2 macrophages from lupus patients and M1 macrophages from healthy subjects. In addition, the probiotic groups showed increased levels of IL-10 and TGF-ß and decreased levels of IL-12, IL1-ß, and TNF-α in MDMs from both healthy and lupus subjects compared to the LPS groups. Although there was a higher expression of pro-inflammatory cytokines in lupus patients, there was a higher expression of anti-inflammatory cytokines in healthy subjects. In general, L. delbrueckii and L. rhamnosus could induce anti-inflammatory effects on MDMs from both healthy and lupus subjects.

Type I/II Immune Balance Contributes to the Protective Effect of AIF-1 on Hepatic Immunopathology Induced by Schistosoma japonicum in a Transgenic Mouse Model.

Schistosomiasis is the second most debilitating neglected tropical disease in the world. Liver egg granuloma and fibrosis are the main damage of schistosomiasis. In this study, the role of allograft inflammatory factor-1 (AIF-1) in liver pathology and its regulation in immune responses were investigated in a transgenic mouse infected with Schistosoma japonicum. We found that AIF-1 overexpression reduced worm burden and decreased egg granuloma sizes and serum alanine aminotransferase levels, along with inhibited hepatic collagen deposition and serum hydroxyproline levels during S. japonicum infection. Moreover, AIF-1 overexpression resulted in an increased ratio of Th1/Th2, increased levels of IFN-γ and T-bet, and lower levels of GATA-3 in the spleen, accompanied by increased M1 percentages, decreased M2 percentages, and thus a higher ratio of M1/M2 in the peritoneal cavity and liver. AIF-1 induced CD68 and iNOS mRNA expression and protein levels of cytoplasmic p-P38 and nuclear NF-κB, along with enhanced levels of TNF-α and TGF-ß in macrophages in vitro. Moreover, the hepatic pathology had a negative correlation with Th1/Th2 and M1/M2 ratios in the infected mice. The findings reveal that the beneficial role of AIF-1 in alleviating hepatic damage is related to restoring type I/II immune balance in S. japonicum infection.

Application of Nanomedicine in Tumor Targeting Inflammatory Pathway.

Given the threat of ever-growing cancer morbidity, it is a cutting-edge frontier for multiple disciplines to apply nanotechnology in cancer therapy. Nanomedicine is now perpetually influencing the diagnosis and treatment of cancer. Meanwhile, tumorigenesis and cancer progression are intimately associated with inflammation. Inflammation can implicate in various tumor progression via the same or different pathways. Therefore, current nanomedicines exhibit tumor-suppressing function through inflammatory pathways. At present, the comprehensive understanding and research on the mechanism of various nanoparticles in cancer treatment are still in progress. In this review, we summarized the applications of nanomedicine in tumor-targeting inflammatory pathways, suggesting that nanoparticles could be a budding star for cancer therapy.

Calcitriol restrains microglial M1 polarization and alleviates dopaminergic degeneration in hemiparkinsonian mice by boosting regulatory T-cell expansion.

OBJECTIVE: Vitamin D deficiency is a risk factor for Parkinson's disease (PD) and vitamin D supplementation robustly alleviates neurodegeneration in PD models. However, the mechanisms underlying this effect require further clarification. Current evidence suggests that harnessing regulatory T cells (Treg) may mitigate neuronal degeneration. In this study, we investigated the therapeutic effects of vitamin D receptor activation by calcitriol on PD, specifically focusing on its role in Treg. METHODS: Hemiparkinsonian mice model was established through the injection of 6-OHDA into the striatum. Mice were pretreated with calcitriol before 6-OHDA injection. The motor performance, dopaminergic neuronal survival, contents of dopamine, and dopamine metabolites were evaluated. The pro-inflammatory cytokines levels, T-cell infiltration, mRNA expression of indicated microglial M1/M2 phenotypic markers, and microglial marker in the midbrain were detected. Populations of Treg in the splenic tissues were assessed using a flow cytometry assay. PC61 monoclonal antibody was applied to deplete Treg in vivo. RESULTS: We show that calcitriol supplementation notably improved motor performance and reduced dopaminergic degeneration in the 6-OHDA-induced PD model. Mechanistically, calcitriol promoted anti-inflammatory/neuroprotective Treg and inhibited pro-inflammatory/neurodestructive effector T-cell generation in this model. This process significantly inhibited T-cell infiltration in the midbrain, restrained microglial activation, microglial M1 polarization, and decreased pro-inflammatory cytokines release. This more favorable inflammatory microenvironment rescued dopaminergic degeneration. To further verify that the anti-inflammatory effects of calcitriol are associated with Treg expansion, we applied an antibody-mediated Treg depletion assay. As predicted, the anti-inflammatory effects of calcitriol in the PD model were diminished following Treg depletion. CONCLUSION: These findings suggest that calcitriol's anti-inflammatory and neuroprotective effects in PD are associated with its potential to boost Treg expansion.

The effect of Jian Gan powder on the proliferation, migration and polarization of macrophages and relative mechanism.

CONTEXT: Jian Gan powder (JGP) is a Chinese medicine compound comprised ginseng, Radix Paeoniae Alba, Radix Astragali, Salvia miltiorrhiza, Yujin, Rhizoma Cyperi, Fructus aurantii, Sophora flavescens, Yinchen, Bupleurum and licorice. OBJECTIVE: This study explored the inhibitory effects, polarization and potential mechanisms associated with JGP in macrophages. MATERIALS AND METHODS: RAW264.7 cells were randomly divided into six groups for 24 h: control, lipopolysaccharide (LPS), overexpression, 1% JGP, 2% JGP, 4% JGP, 8% JGP and 16% JGP. The effects of JGP on RAW264.7 cell proliferation were assessed using colony formation assays and cell counting kit-8 (CCK-8) assays. The Transwell assay was used to evaluate its impact on RAW264.7 cell migration. Moreover, we analysed the interleukin-6 (IL-6)/signal transducer and activator of the transcription 3 (IL-6/STAT3) signaling pathway using quantitative real-time PCR and Western blotting. Furthermore, we examined the M1/M2 polarization levels. RESULTS: Unlike LPS stimulation, JGP serum treatment markedly suppressed macrophage proliferation and migration capacity, while STAT3 overexpression enhanced RAW264.7 cell proliferation and migration. JGP inhibited the proliferation and migration of RAW264.7 cells by attenuating the IL-6/STAT3 signaling pathway. Furthermore, it inhibited macrophage M1 polarization, promoting M2 polarization. DISCUSSION AND CONCLUSIONS: JGP effectively suppressed the cellular function of RAW264.7 cells by down-regulating the IL-6/STAT3 signaling pathway and modulating macrophage M1/M2 polarization. These findings provide valuable theoretical and experimental basis for considering the potential clinical application of JGP in the treatment of immune-mediated liver injury in clinical practice.

Metabotropic Glutamate Receptor 8 Suppresses M1 Polarization in Microglia by Alleviating Endoplasmic Reticulum Stress and Mitochondrial Dysfunction.

BACKGROUND: Microglia-mediated neuroinflammation is a hallmark of neurodegeneration. Metabotropic glutamate receptor 8 (GRM8) has been reported to promote neuronal survival in neurodegenerative diseases, yet the effect of GRM8 on neuroinflammation is still unclear. Calcium overload-induced endoplasmic reticulum (ER)-mitochondrial miscommunication has been reported to trigger neuroinflammation in the brain. The aim of this study was to investigate putative anti-inflammatory effects of GRM8 in microglia, specifically focusing on its role in calcium overload-induced ER stress and mitochondrial dysfunction. METHODS: BV2 microglial cells were pretreated with GRM8 agonist prior to lipopolysaccharide administration. Pro-inflammatory cytokine levels and the microglial polarization state in BV2 cells were then quantified. Cellular apoptosis and the viability of neuron-like PC12 cells co-cultured with BV2 cells were examined using flow cytometry and a Cell Counting Kit-8, respectively. The concentration of cAMP, inositol-1,4,5-triphosphate receptor (IP3R)-dependent calcium release, ER Ca2+ concentration, mitochondrial function as reflected by reactive oxygen species levels, ATP production, mitochondrial membrane potential, expression of ER stress-sensing protein, and phosphorylation of the nuclear factor kappa B (NF-κB) p65 subunit were also quantified in BV2 cells. RESULTS: GRM8 activation inhibited pro-inflammatory cytokine release and shifted microglia polarization towards an anti-inflammatory-like phenotype in BV2 cells, as well as promoting neuron-like PC12 cell survival when co-cultured with BV2 cells. Mechanistically, microglial GRM8 activation significantly inhibited cAMP production, thereby desensitizing the IP3R located within the ER. This process markedly limited IP3R-dependent calcium release, thus restoring mitochondrial function while inhibiting ER stress and subsequently deactivating NF-κB signaling. CONCLUSIONS: Our results indicate that GRM8 activation can protect against microglia-mediated neuroinflammation by attenuating ER stress and mitochondrial dysfunction, and that IP3R-mediated calcium signaling may play a vital role in this process. GRM8 may thus be a potential target for limiting neuroinflammation.

METTL3 Mediates Microglial Activation and Blood-Brain Barrier Permeability in Cerebral Ischemic Stroke by Regulating NLRP3 Inflammasomes Through m6A Methylation Modification.

Cerebral ischemic stroke (CIS) is the main cause of disability. METTL3 is implicated in CIS, and we explored its specific mechanism. Middle cerebral artery occlusion (MCAO) rat model and oxygen-glucose deprivation/reperfusion (OGD/R) HAPI cell model were established and treated with LV-METTL3 or DAA, oe-METTL3, miR-335-3p mimics, or DAA, to assess their effects on MCAO rat neurological and motor function, cerebral infarction area, brain water content, microglial activation, blood-brain barrier (BBB) permeability, and NLRP3 inflammasome activation. METTL3, pri-miR-335-3p, mature miR-335-3p, and miR-335-3p mRNA levels were assessed by RT-qPCR; M1/M2 microglial phenotype proportion and M1/M2 microglia ratio, inflammatory factor levels, and m6A modification were assessed. MCAO rats manifested cerebral ischemia injury. METTL3 was under-expressed in CIS. METTL3 overexpression inhibited microglial activation and M1 polarization and BBB permeability in MCAO rats and inhibited OGD/R-induced microglial activation and reduced M1 polarization. METTL3 regulated miR-335-3p expression and inhibited NLRP3 inflammasome activation. m6A methylation inhibition averted METTL3's effects on NLRP3 activation, thus promoting microglial activation in OGD/R-induced cells and METTL3's effects on BBB permeability in MCAO rats. Briefly, METTL3 regulated miR-335-3p expression through RNA m6A methylation and inhibited NLRP3 inflammasome activation, thus repressing microglial activation, BBB permeability, and protecting against CIS.

Macrophage Polarization and Osteoclast Differentiation.

Macrophages are a key player to regulate rheumatoid arthritis pathogenesis from onset to remission. They can alter innate functions under microenvironmental conditions. To understand heterogeneous functions of macrophages in rheumatoid arthritis, several activated statuses of macrophages should be mimicked in vitro. Here, we describe basic protocols for macrophage polarization and osteoclast differentiation.

PRMT2 silencing regulates macrophage polarization through activation of STAT1 or inhibition of STAT6.

BACKGROUND: Macrophages play significant roles in innate immune responses and are heterogeneous cells that can be polarized into M1 or M2 phenotypes. PRMT2 is one of the type I protein arginine methyltransferases involved in inflammation. However, the role of PRMT2 in M1/M2 macrophage polarization remains unclear. Our study revealed the effect and mechanism of PRMT2 in macrophage polarization. METHODS: Bone marrow-derived macrophages (BMDMs) were polarized to M1 or M2 state by LPS plus murine recombinant interferon-γ (IFN-γ) or interleukin-4 (IL-4). Quantitative polymerase chain reaction (qPCR), western blot and flow cytometry (FCM) assay were performed and analyzed markers and signaling pathways of macrophage polarization. RESULTS: We found that PRMT2 was obviously upregulated in LPS/IFN-γ-induced M1 macrophages, but it was little changed in IL-4-induced M2 macrophages. Furthermore, PRMT2 konckdown increased the expression of M1 macrophages markers through activation of STAT1 and decreased the expression of M2 macrophages markers through inhibition of STAT6. CONCLUSIONS: PRMT2 silencing modulates macrophage polarization by activating STAT1 to promote M1 and inhibiting STAT6 to attenuate the M2 state.

Interleukin-37 ameliorates periodontitis development by inhibiting NLRP3 inflammasome activation and modulating M1/M2 macrophage polarization.

OBJECTIVE: Our study was designed to explore the role of IL-37 in M1/M2 macrophage polarization imbalance in the pathogenesis of periodontitis. BACKGROUND: Periodontitis is a chronic progressive inflammatory disease featured by gingival inflammation and alveolar bone resorption. Recent research has revealed that regulating macrophage polarization is a viable method to ameliorate periodontal inflammation. IL-37 is an anti-inflammatory cytokine, which has been reported to inhibit innate and adaptive immunity. METHODS: For in vitro experiment, mouse macrophage RAW264.7 cells were pretreated with 0.1 ng/mL recombinant human IL-37. M1 and M2 polarizations of RAW264.7 cells were induced by 100 ng/mL LPS and 20 ng/mL IL-4, respectively. The expression of M1 (iNOS, TNF-α, and IL-6) and M2 (CD206, Arg1, and IL-10) phenotype markers in RAW264.7 cells was detected by RT-qPCR, western blotting, and immunofluorescence staining. For in vivo experiment, experimental periodontitis mouse models were established by sterile silk ligation (5-0) around the bilateral maxillary second molar of mice for 1 week. H&E staining of the maxillary alveolar bone was used to show the resorption of root cementum and dentin. Alveolar bone loss in mouse models was evaluated through micro-CT analysis. The expression of iNOS and CD206 in gingival tissues was assessed by immunohistochemistry staining. NLRP3 inflammasome activation was confirmed by western blotting. RESULTS: IL-37 pretreatment reduced iNOS, TNF-α, and IL-6 expression in LPS-treated RAW264.7 cells but increased CD206, Arg1, and IL-10 in IL-4-treated RAW264.7 cells. LPS-induced upregulation in NLRP3, GSDMD, cleaved-IL-1ß, and cleaved-caspase-1 expression was antagonized by IL-37 treatment. In addition, IL-37 administration ameliorated the resorption of root cementum and dentin in periodontitis mouse models. IL-37 prominently decreased iNOS+ cell population but increased CD206+ cell population in gingival tissues of periodontitis mice. The enhancement in NLRP3, GSDMD, cleaved-IL-1ß, and cleaved-caspase-1 expression in the gingival tissues of periodontitis mice was offset by IL-37 administration. CONCLUSION: IL-37 prevents the progression of periodontitis by suppressing NLRP3 inflammasome activation and mediating M1/M2 macrophage polarization.

Knockdown of BCL-3 Attenuates Inflammatory Response in Intracerebral Hemorrhage Through an rBMECs/MGs Microenvironment.

Intracerebral hemorrhage (ICH) is a severe disease with high mortality. Recently, the role of BCL-3 in ICH has started to gain attention, but its mechanism remains unclear. A collagenase injection method was used to establish an ICH model in rats, and the expression of BCL-3 were detected. Rat brain microvascular endothelial cells (rBMECs) were isolated and induced with Hemin to establish an in vitro ICH model. The expression of BCL-3 was assessed, followed by detection of cell apoptosis. In the cell model, the recruitment, polarization, and pro-inflammatory features of the microglia (MGs) were assessed after co-cultured with rBMECs. Finally, in the ICH animal model, after knockdown of BCL-3, comprehensive evaluations of inflammatory responses in brain tissue, polarization and recruitment of microglia, and apoptosis were conducted. Results revealed an upregulated expression of BCL-3 in brain tissue of the ICH animal model. In Hemin-treated rBMECs, an upward trend in BCL-3 expression was observed, accompanied by an increase of cell apoptosis. After co-culturing with the in vitro model, microglia exhibited enhanced M1 polarization and intensified inflammatory responses. However, when BCL-3 expression was inhibited in the in vitro model, a reversal occurred in the polarization tendency and inflammatory responses of microglia. Additionally, after knockdown of BCL-3 in the animal model, notable improvements occurred in M1 polarization, infiltration of macrophages, and inflammatory reactions in the brain tissue. Therefore, BCL-3 modulates the inflammatory response after ICH occurrence through the BMECs/MGs microenvironment. Additionally, BCL-3 might be a potential therapeutic target for ICH management.

Modulating the polarization phenotype of microglia - A valuable strategy for central nervous system diseases.

Central nervous system (CNS) diseases have become one of the leading causes of death in the global population. The pathogenesis of CNS diseases is complicated, so it is important to find the patterns of the disease to improve the treatment strategy. Microglia are considered to be a double-edged sword, playing both harmful and beneficial roles in CNS diseases. Therefore, it is crucial to understand the progression of the disease and the changes in the polar phenotype of microglia to provide guidance in the treatment of CNS diseases. Microglia activation may evolve into different phenotypes: M1 and M2 types. We focused on the roles that M1 and M2 microglia play in regulating intercellular dialogues, pathological reactions and specific diseases in CNS diseases. Importantly, we summarized the strategies used to modulate the polarization phenotype of microglia, including traditional pharmacological modulation, biological therapies, and physical strategies. This review will contribute to the development of potential strategies to modulate microglia polarization phenotypes and provide new alternative therapies for CNS diseases.

Inhibition of focal adhesion kinase 2 results in a macrophage polarization shift to M2 which attenuates local and systemic inflammation and reduces heterotopic ossification after polysystem extremity trauma.

Introduction: Heterotopic ossification (HO) is a complex pathology often observed in combat injured casualties who have sustained severe, high energy polytraumatic extremity injuries. Once HO has developed, prophylactic therapies are limited outside of surgical excision. Tourniquet-induced ischemia injury (IR) exacerbates trauma-mediated musculoskeletal tissue injury, inflammation, osteogenic progenitor cell development and HO formation. Others have shown that focal adhesion kinase-2 (FAK2) plays a key role in regulating early inflammatory signaling events. Therefore, we hypothesized that targeting FAK2 prophylactically would mitigate extremity trauma induced IR inflammation and HO formation. Methods: We tested whether the continuous infusion of a FAK2 inhibitor (Defactinib, PF-573228; 6.94 µg/kg/min for 14 days) can mitigate ectopic bone formation (HO) using an established blast-related extremity injury model involving femoral fracture, quadriceps crush injury, three hours of tourniquet-induced limb ischemia, and hindlimb amputation through the fracture site. Tissue inflammation, infiltrating cells, osteogenic progenitor cell content were assessed at POD-7. Micro-computed tomography imaging was used to quantify mature HO at POD-56. Results: In comparison to vehicle control-treated rats, FAK2 administration resulted in no marked wound healing complications or weight loss. FAK2 treatment decreased HO by 43%. At POD-7, marked reductions in tissue proinflammatory gene expression and assayable osteogenic progenitor cells were measured, albeit no significant changes in expression patterns of angiogenic, chondrogenic and osteogenic genes. At the same timepoint, injured tissue from FAK-treated rats had fewer infiltrating cells. Additionally, gene expression analyses of tissue infiltrating cells resulted in a more measurable shift from an M1 inflammatory to an M2 anti-inflammatory macrophage phenotype in the FAK2 inhibitor-treated group. Discussion: Our findings suggest that FAK2 inhibition may be a novel strategy to dampen trauma-induced inflammation and attenuate HO in patients at high risk as a consequence of severe musculoskeletal polytrauma.

Azithromycin with scaling and root planing versus scaling and root planing alone in the treatment of periodontitis: A randomized controlled trial.

Background: The growing interest in the possibilities of macrophages modulation with therapeutic purposes promotes new approaches for periodontitis treatment. Aim: The aim of this randomized controlled open clinical study was to evaluate the early clinical and immunological effects of the long-course azithromycin as an adjunct to scaling and root planing in periodontitis. Methods: 50 patients (with stage I-III, grade A/B periodontitis) and 22 periodontally healthy volunteers as the reference group were recruited. Following scaling and root planing (SRP), the patients were randomly assigned to one of two treatment modalities: SRP only (n = 25) and adjunct azithromycin (Az) treatment (n = 25). The patients were monitored at baseline, and 30 ± 5 days after therapy. Clinical attachment loss (CAL), periodontal probing depth (PPD) and bleeding on probing (BoP) were evaluated. Secondary outcome measures included mean changes in single-positive CD68 + and CD163 + macrophages (Mφs) density and ratio, evaluated by immunohistochemistry, and IL1-ß, IL-6, IL-10, TGF-ß levels, detected by ELISA. Results: At 1 month both groups showed significant improvements of CAL, PPD and BoP, without significant added benefit in terms of CAL, PPD and BoP of Az. But Az increased the density of CD68 + and CD163 + Mφs (P < 0.0001), decreased the CD68+/CD163 + ratio (P = 0.043), decreased IL-1ß (P < 0.01), IL-6 (P < 0.001) levels, and increased IL-10 (P < 0.0001) and TGF-ß (P < 0.001) levels compared to SRP and periodontitis at baseline. Conclusion: The long course of Az demonstrated modulation of CD68 + and CD163 + Mφs towards M2 polarization, which may play a significant role in achieving favorable long-term treatment outcomes. ClinicalTrials.gov.