Effects of IRF1 and IFN-β interaction on the M1 polarization of macrophages and its antitumor function

Artesunate alleviates sepsis-induced liver injury by regulating macrophage polarization via the lncRNA MALAT1/PTBP1/IFIH1 axis

BACKGROUND

The present study aimed to explore the regulatory effects of artesunate on macrophage polarization in sepsis.

METHODS

Cell models and mice models were established using lipopolysaccharide (LPS), followed by treatment with various concentrations of artesunate. The phenotype of the macrophages was determined by flow cytometry. RNA immunoprecipitation was used to confirm the binding between MALAT1 and polypyrimidine tract-binding protein 1 (PTBP1), as well as between PTBP1 and interferon-induced helicase C domain-containing protein 1 (IFIH1).

RESULTS

Treatment with artesunate inhibited M1 macrophage polarization in Kupffer cells subjected to LPS stimulation by downregulating MALAT1. Furthermore, MALAT1 abolished the inhibitory effect of artesunate on M1 macrophage polarization by recruiting PTBP1 to promote IFIH. In vivo experiments confirmed that artesunate alleviated septic liver injury by affecting macrophage polarization via MALAT1.

CONCLUSION

The present study showed that artesunate alleviates LPS-induced sepsis in Kupffer cells by regulating macrophage polarization via the lncRNA MALAT1/PTBP1/IFIH1 axis.

Tumoral Interferon Beta Induces an Immune-Stimulatory Phenotype in Tumor-Associated Macrophages in Melanoma Brain Metastases

Type I interferons (IFN) are immune-stimulatory cytokines involved in antiviral and antitumor immune responses. They enhance the efficacy of immunogenic anticancer therapies such as radiotherapy by activating both innate and adaptive immune cells. Macrophages are one of the most abundant innate immune cells in the immune microenvironment of melanoma brain metastases (MBM) and can exert potent immune-suppressive functions. Here, we investigate the potential of tumoral type I IFNs to repolarize tumor-associated macrophages (TAM) in two murine MBM models and assess the effects of radiotherapy-induced type I IFN on TAMs in a transcriptomic MBM patient dataset. In mice, we describe a proinflammatory M1-like TAM phenotype induced by tumoral IFNβ and identify a myeloid type I IFN-response signature associated with a high M1/M2-like TAM ratio. Following irradiation, patients with MBM displaying a myeloid type I IFN-response signature showed increased overall survival, providing evidence that tumoral IFNβ supports an effective antitumor immune response by re-educating immune-regulatory TAM. These findings uncover type I IFN-inducing therapies as a potential macrophage-targeting therapeutic approach and provide a rationale for combining radiotherapy with concomitant immunotherapy to improve treatment response in patients with MBM.

SIGNIFICANCE

Our study shows that re-education of tumor-associated macrophages by tumoral IFNβ translates into improved clinical outcome in patients with melanoma brain metastases, providing pathomechanistic insights into synergistic type I interferon-inducing therapies with immunotherapies and warranting investigation of IFNβ as a predictive biomarker for combined radioimmunotherapy.

TLR3 agonism augments CD47 inhibition in acute myeloid leukemia

CD47-SIRPa is a myeloid check point pathway that promotes phagocytosis of cells lacking markers for self-recognition. Tumor cells can overexpress CD47 and bind to SIRPa on macrophages, preventing phagocytosis. CD47 expression is enhanced and correlated with a negative prognosis in acute myeloid leukemia (AML), with its blockade leading to cell clearance. ALX90 is an engineered fusion protein with high affinity for CD47. Composed of the N-terminal D1 domain of SIRPα genetically linked to an inactive Fc domain from human immunoglobulin (Ig) G, ALX90 is designed to avoid potential toxicity of CD47-expressing red blood cells. Venetoclax (VEN) is a specific B-cell lymphoma-2 (BCL-2) inhibitor that can restore apoptosis in malignant cells. In AML, VEN is combined with azanucleosides to induce superior remission rates, however treatment for refractory/relapse is an unmet need. We questioned whether the anti-tumor activity of a VENbased regimen can be augmented through CD47 inhibition (CD47i) in AML and how this triplet may be enhanced. Human AML cell lines were sensitive to ALX90 and its addition increased efficacy of a VEN plus azacitidin (VEN+AZA) regimen in vivo. However, CD47i failed to clear bone marrow tumor burden in PDX models. We hypothesized that the loss of resident macrophages in the bone marrow in AML reduced efficiency of CD47i. Therefore, we attempted to enhance this medullary macrophage population with agonism of TLR3 via polyinosinic:polycytidylic acid (poly(I:C)), which led to expansion and activation of medullary macrophages in in vivo AML PDX models and potentiated CD47i. In summary, the addition of poly(I:C) can enhance medullary macrophage populations to potentiate the phagocytosis merited by therapeutic inhibition of CD47.

Macrophage polarisation and inflammatory mechanisms in atherosclerosis: Implications for prevention and treatment

Atherosclerosis is a chronic inflammatory disease characterised by plaque accumulation in the arteries. Macrophages are immune cells that are crucial in the development of atherosclerosis. Macrophages can adopt different phenotypes, with the M1 phenotype promoting inflammation while the M2 phenotype counteracting it. This review focuses on the factors that drive the polarisation of M1 macrophages towards a pro-inflammatory phenotype during AS. Additionally, we explored metabolic reprogramming mechanisms and cytokines secretion by M1 macrophages. Hyperlipidaemia is widely recognised as a major risk factor for atherosclerosis. Modified lipoproteins released in the presence of hyperlipidaemia can trigger the release of cytokines and recruit circulating monocytes, which adhere to the damaged endothelium and differentiate into macrophages. Macrophages engulf lipids, leading to the formation of foam cells. As atherosclerosis progresses, foam cells become the necrotic core within the atherosclerotic plaques, destabilising them and triggering ischaemic disease. Furthermore, we discuss recent research focusing on targeting macrophages or inflammatory pathways for preventive or therapeutic purposes. These include statins, PCSK9 inhibitors, and promising nanotargeted drugs. These new developments hold the potential for the prevention and treatment of atherosclerosis and its related complications.

C5aR1 inhibition reprograms tumor associated macrophages and reverses PARP inhibitor resistance in breast cancer

Although Poly (ADP-ribose) polymerase (PARP) inhibitors (PARPi) have been approved in multiple diseases, including BRCA1/2 mutant breast cancer, responses are usually transient requiring the deployment of combination therapies for optimal efficacy. Here we thus explore mechanisms underlying sensitivity and resistance to PARPi using two intrinsically PARPi sensitive (T22) and resistant (T127) syngeneic murine breast cancer models in female mice. We demonstrate that tumor associated macrophages (TAM) potentially contribute to the differential sensitivity to PARPi. By single-cell RNA-sequencing, we identify a TAM_C3 cluster, expressing genes implicated in anti-inflammatory activity, that is enriched in PARPi resistant T127 tumors and markedly decreased by PARPi in T22 tumors. Rps19/C5aR1 signaling is selectively elevated in TAM_C3. C5aR1 inhibition or transferring C5aR1hi cells increases and decreases PARPi sensitivity, respectively. High C5aR1 levels in human breast cancers are associated with poor responses to immune checkpoint blockade. Thus, targeting C5aR1 may selectively deplete pro-tumoral macrophages and engender sensitivity to PARPi and potentially other therapies.

Effect of 2-methoxyestradiol on mammary tumor initiation and progression

BACKGROUND

The anti-cancer agent 2-methoxyestradiol (2-ME) has been shown to have anti-proliferative and anti-angiogenic properties. Previously, the effect of 2-ME on early- and late-stage breast cancer (BC) was investigated in vivo using a transgenic mouse model (FVB/N-Tg(MMTV-PyVT)) of spontaneous mammary carcinoma. Anti-tumor effects were observed in late-stage BC with no effect on early-stage BC. Given the contrasting results obtained from the different BC stages, we have now investigated the effect of 2-ME when administered before the appearance of palpable tumors.

METHODS

Each mouse received 100 mg/kg 2-ME on day 30 after birth, twice per week for 28 days, while control mice received vehicle only. Animals were terminated on day 59. Lung and mammary tissue were obtained for immunohistochemical analysis of CD163 and CD3 expression, and histological examination was performed to analyze tumor necrosis. Additionally, blood samples were collected to measure plasma cytokine levels.

RESULTS

2-ME increased tumor mass when compared to the untreated animals (p = .0139). The pro-tumorigenic activity of 2-ME was accompanied by lower CD3+ T-cell numbers in the tumor microenvironment (TME) and high levels of the pro-inflammatory cytokine interleukin (IL)-1β. Conversely, 2-ME-treatment resulted in fewer CD163+ cells detectable in the TME, increased levels of tumor necrosis, increased IL-10 plasma levels, and low IL-6 and IL-27 plasma levels.

CONCLUSION

Taken together, these findings suggest that 2-ME promotes early-stage BC development.

Anti-Interferon-γ Therapy for Cytokine Storm Syndromes

A vast body of evidence provides support to a central role of exaggerated production of interferon-γ (IFN-γ) in causing hypercytokinemia and signs and symptoms of hemophagocytic lymphohistiocytosis (HLH). In this chapter, we will describe briefly the roles of IFN-γ in innate and adaptive immunity and in host defense, summarize results from animal models of primary HLH and secondary HLH with particular emphasis on targeted therapeutic approaches, review data on biomarkers associated with activation of the IFN-γ pathway, and discuss initial efficacy and safety results of IFN-γ neutralization in humans.

KLF17 is an important regulatory component of the transcriptomic response of Atlantic salmon macrophages to Piscirickettsia salmonis infection

Piscirickettsia salmonis is the most important health problem facing Chilean Aquaculture. Previous reports suggest that P. salmonis can survive in salmonid macrophages by interfering with the host immune response. However, the relevant aspects of the molecular pathogenesis of P. salmonis have been poorly characterized. In this work, we evaluated the transcriptomic changes in macrophage-like cell line SHK-1 infected with P. salmonis at 24- and 48-hours post-infection (hpi) and generated network models of the macrophage response to the infection using co-expression analysis and regulatory transcription factor-target gene information. Transcriptomic analysis showed that 635 genes were differentially expressed after 24- and/or 48-hpi. The pattern of expression of these genes was analyzed by weighted co-expression network analysis (WGCNA), which classified genes into 4 modules of expression, comprising early responses to the bacterium. Induced genes included genes involved in metabolism and cell differentiation, intracellular transportation, and cytoskeleton reorganization, while repressed genes included genes involved in extracellular matrix organization and RNA metabolism. To understand how these expression changes are orchestrated and to pinpoint relevant transcription factors (TFs) controlling the response, we established a curated database of TF-target gene regulatory interactions in Salmo salar, SalSaDB. Using this resource, together with co-expression module data, we generated infection context-specific networks that were analyzed to determine highly connected TF nodes. We found that the most connected TF of the 24- and 48-hpi response networks is KLF17, an ortholog of the KLF4 TF involved in the polarization of macrophages to an M2-phenotype in mammals. Interestingly, while KLF17 is induced by P. salmonis infection, other TFs, such as NOTCH3 and NFATC1, whose orthologs in mammals are related to M1-like macrophages, are repressed. In sum, our results suggest the induction of early regulatory events associated with an M2-like phenotype of macrophages that drives effectors related to the lysosome, RNA metabolism, cytoskeleton organization, and extracellular matrix remodeling. Moreover, the M1-like response seems delayed in generating an effective response, suggesting a polarization towards M2-like macrophages that allows the survival of P. salmonis. This work also contributes to SalSaDB, a curated database of TF-target gene interactions that is freely available for the Atlantic salmon community.

Synergistic Effects of Azithromycin and STING Agonist Promote IFN-I Production by Enhancing the Activation of STING-TBK1 Signaling

Background

Azithromycin (AZM) is a macrolide antibiotic that exhibits anti-inflammatory and anti-viral infection properties by enhancing type-I interferon (IFN-I) responses. The stimulator of interferon genes (STING) can directly induce IFN-I production. However, elevated IFN-I induces auto-immune phenotypes such as systemic lupus erythematosus (SLE). The effects of AZM and STING on the production of IFN-I are unclear.

Objective

Therefore, this study aims to evaluate the role of AZM and STING on IFN-I responses in macrophages.

Methods

RAW 264.7 macrophages were treated with AZM with and without a STING-agonist (DMXAA), and the maturation of macrophages was determined using flow cytometry. Gene expression and pro-inflammatory cytokines were analyzed using qPCR and ELISA, respectively. Moreover, protein expression was investigated using Western blot assays and immunofluorescence.

Results

Our results show that AZM significantly induced M1 phenotypes, promoting surface molecule expansion of CD80 and MHC-II and production of IL-6 and TNF-α cytokines on DMXAA-stimulated macrophages. Furthermore, we found that AZM-increased mRNA levels of interferon-stimulated genes (ISGs) could be due to the high expression of STNG-TBK1 signaling in the presence of DMXAA.

Conclusion

Our data suggest that AZM enhancement of IFN-I responses was STING dependent in DMXAA-stimulated macrophages. These data underline a novel approach to AZM action-mediated STING-TBK1 signaling for regulating IFN-I responses and may further augment the scientific basis and potential use of AZM in clinical applications.

Harnessing strategies for enhancing diabetic wound healing from the perspective of spatial inflammation patterns

Diabetic wound is a great threat to patient's health and lives. The refractory diabetic wound shows spatial inflammation patterns, in which the early-wound pattern depicts a deprived acute inflammatory response, and the long-term non-healing wound pattern delineates an excessive and persistent inflammation due to the delayed immune cell infiltration in a positive feedback loop. In this work, we give points to some strategies to normalize the dysregulated immune process based on the spatial inflammation pattern differences in diabetic wound healing. First of all, inhibiting inflammatory response to avoid subsequent persistent and excessive immune infiltration for the early diabetic wound is proposed. However, diabetic wounds are unperceptive trauma that makes patients miss the best treatment time. Therefore, we also introduce two strategies for the long-term non-healing diabetic wound. One strategy is about changing chronic wounds to acute ones, which aims to rejuvenate M1 macrophages in diabetic wounds and make spontaneous M2 polarization possible. To activate the controllable proinflammatory response, western medicine delivers proinflammatory molecules while traditional Chinese medicine develops "wound-pus promoting granulation tissue growth theory". Another strategy to solve long-term non-healing wounds is seeking switches that target M1/M2 transition directly. These investigations draw a map that delineates strategies for enhancing diabetic wound healing from the perspective of spatial inflammation patterns systematically.

Transcriptomic and proteomic profiling reveals distinct pathogenic features of peripheral non-classical monocytes in systemic lupus erythematosus

Peripheral blood monocytes propagate inflammation in systemic lupus erythematosus (SLE). Three major populations of monocytes have been recognized namely classical (CM), intermediate (IM) and non-classical monocytes (NCM). Herein, we performed a comprehensive transcriptomic, proteomic and functional characterization of the three peripheral monocytic subsets from active SLE patients and healthy individuals. Our data demonstrate extensive molecular disruptions in circulating SLE NCM, characterized by enhanced inflammatory features such as deregulated DNA repair, cell cycle and heightened IFN signaling combined with differentiation and developmental cues. Enhanced DNA damage, elevated expression of p53, G0 arrest of cell cycle and increased autophagy stress the differentiation potential of NCM in SLE. This immunogenic profile is associated with an activated macrophage phenotype of NCM exhibiting M1 characteristics in the circulation, fueling the inflammatory response. Together, these findings identify circulating SLE NCM as a pathogenic cell type in the disease that could represent an additional therapeutic target.

Agmatine-IRF2BP2 interaction induces M2 phenotype of microglia by increasing IRF2-KLF4 signaling

BACKGROUND

Following central nervous system (CNS) injury, the investigation for neuroinflammation is vital because of its pleiotropic role in both acute injury and long-term recovery. Agmatine (Agm) is well known for its neuroprotective effects and anti-neuroinflammatory properties. However, Agm's mechanism for neuroprotection is still unclear. We screened target proteins that bind to Agm using a protein microarray; the results showed that Agm strongly binds to interferon regulatory factor 2 binding protein (IRF2BP2), which partakes in the inflammatory response. Based on these prior data, we attempted to elucidate the mechanism by which the combination of Agm and IRF2BP2 induces a neuroprotective phenotype of microglia.

METHODS

To confirm the relationship between Agm and IRF2BP2 in neuroinflammation, we used microglia cell-line (BV2) and treated with lipopolysaccharide from Escherichia coli 0111:B4 (LPS; 20 ng/mL, 24 h) and interleukin (IL)-4 (20 ng/mL, 24 h). Although Agm bound to IRF2BP2, it failed to enhance IRF2BP2 expression in BV2. Therefore, we shifted our focus onto interferon regulatory factor 2 (IRF2), which is a transcription factor and interacts with IRF2BP2.

RESULTS

IRF2 was highly expressed in BV2 after LPS treatment but not after IL-4 treatment. When Agm bound to IRF2BP2 following Agm treatment, the free IRF2 translocated to the nucleus of BV2. The translocated IRF2 activated the transcription of Kruppel-like factor 4 (KLF4), causing KLF4 to be induced in BV2. The expression of KLF4 increased the CD206-positive cells in BV2.

CONCLUSIONS

Taken together, unbound IRF2, resulting from the competitive binding of Agm to IRF2BP2, may provide neuroprotection against neuroinflammation via an anti-inflammatory mechanism of microglia involving the expression of KLF4.

Transcriptional regulation on effector T cells in the pathogenesis of psoriasis

Psoriasis is one of the most common inflammatory diseases, characterized by scaly erythematous plaques on the skin. The accumulated evidence on immunopathology of psoriasis suggests that inflammatory reaction is primarily mediated by T helper (Th) cells. The differentiation of Th cells plays important roles in psoriatic progression and it is regulated by transcription factors such as T-bet, GATA3, RORγt, and FOXP3, which can convert naïve CD4+ T cells, respectively, into Th1, Th2, Th17 and Treg subsets. Through the activation of the JAK/STAT and Notch signaling pathways, together with their downstream effector molecules including TNF-α, IFN-γ, IL-17, TGF-β, these subsets of Th cells are then deeply involved in the pathogenesis of psoriasis. As a result, keratinocytes are abnormally proliferated and abundant inflammatory immune cells are infiltrated in psoriatic lesions. We hypothesize that modulation of the expression of transcription factors for each Th subset could be a new therapeutic target for psoriasis. In this review, we will focus on the recent literature concerning the transcriptional regulation of Th cells in psoriasis.

Intravesical BCG in patients with non-muscle invasive bladder cancer induces trained immunity and decreases respiratory infections

BACKGROUND

BCG is recommended as intravesical immunotherapy to reduce the risk of tumor recurrence in patients with non-muscle invasive bladder cancer (NMIBC). Currently, it is unknown whether intravesical BCG application induces trained immunity.

METHODS

The aim of this research was to determine whether BCG immunotherapy induces trained immunity in NMIBC patients. We conducted a prospective observational cohort study in 17 NMIBC patients scheduled for BCG therapy and measured trained immunity parameters at 9 time points before and during a 1-year BCG maintenance regimen. Ex vivo cytokine production by peripheral blood mononuclear cells, epigenetic modifications, and changes in the monocyte transcriptome were measured. The frequency of respiratory infections was investigated in two larger cohorts of BCG-treated and non-BCG treated NMIBC patients as a surrogate measurement of trained immunity. Gene-based association analysis of genetic variants in candidate trained immunity genes and their association with recurrence-free survival and progression-free survival after BCG therapy was performed to investigate the hypothesized link between trained immunity and clinical response.

RESULTS

We found that intravesical BCG does induce trained immunity based on an increased production of TNF and IL-1β after heterologous ex vivo stimulation of circulating monocytes 6-12 weeks after intravesical BCG treatment; and a 37% decreased risk (OR 0.63 (95% CI 0.40 to 1.01)) for respiratory infections in BCG-treated versus non-BCG-treated NMIBC patients. An epigenomics approach combining chromatin immuno precipitation-sequencing and RNA-sequencing with in vitro trained immunity experiments identified enhanced inflammasome activity in BCG-treated individuals. Finally, germline variation in genes that affect trained immunity was associated with recurrence and progression after BCG therapy in NMIBC.

CONCLUSION

We conclude that BCG immunotherapy induces trained immunity in NMIBC patients and this may account for the protective effects against respiratory infections. The data of our gene-based association analysis suggest that a link between trained immunity and oncological outcome may exist. Future studies should further investigate how trained immunity affects the antitumor immune responses in BCG-treated NMIBC patients.

Macrophages: From Simple Phagocyte to an Integrative Regulatory Cell for Inflammation and Tissue Regeneration-A Review of the Literature

The understanding of macrophages and their pathophysiological role has dramatically changed within the last decades. Macrophages represent a very interesting cell type with regard to biomaterial-based tissue engineering and regeneration. In this context, macrophages play a crucial role in the biocompatibility and degradation of implanted biomaterials. Furthermore, a better understanding of the functionality of macrophages opens perspectives for potential guidance and modulation to turn inflammation into regeneration. Such knowledge may help to improve not only the biocompatibility of scaffold materials but also the integration, maturation, and preservation of scaffold-cell constructs or induce regeneration. Nowadays, macrophages are classified into two subpopulations, the classically activated macrophages (M1 macrophages) with pro-inflammatory properties and the alternatively activated macrophages (M2 macrophages) with anti-inflammatory properties. The present narrative review gives an overview of the different functions of macrophages and summarizes the recent state of knowledge regarding different types of macrophages and their functions, with special emphasis on tissue engineering and tissue regeneration.

FOXP1 inhibits pancreatic cancer growth by transcriptionally regulating IRF1 expression

FOXP1, known as a Forkhead-box (FOX) family protein, plays an important role in human tumorigenesis. However, the function and molecular mechanism of FOXP1 in pancreatic cancer (PC) remain unclear. Here, we report that PC patients with FOXP1 overexpression had a higher survival rate compared to patients with low- FOXP1 expression. Additionally, high expression of FOXP1 can markedly inhibit the growth of pancreatic cancer in vivo and in vitro, whereas low expression of FOXP1 effectively promoted the tumorigenesis. Mechanistically, FOXP1 could directly bind the IRF1 promoter, which triggered the transcriptional activity of IRF1. Taken together, FOXP1 suppressed PC growth via IRF1-dependent manner, serving as a potential prognostic biomarker for patients with PC.

Tumor-Homing and Immune-Reprogramming Cellular Nanovesicles for Photoacoustic Imaging-Guided Phototriggered Precise Chemoimmunotherapy

Many studies have focused on developing effective therapeutic strategies to selectively destroy primary tumors, eliminate metastatic lesions, and prevent tumor recurrence with minimal side effects on normal tissues. In this work, we synthesized engineered cellular nanovesicles (ECNVs) with tumor-homing and immune-reprogramming functions for photoacoustic (PA) imaging-guided precision chemoimmunotherapy. M1-macrophage-derived cellular nanovesicles (CNVs) were loaded with gold nanorods (GNRs), gemcitabine (GEM), CpG ODN, and PD-L1 aptamer. The good histocompatibility and tumor-homing effect of CNVs improved drug retention in the bloodstream and led to their enrichment in tumor tissues. Furthermore, the photothermal ability of GNRs enabled PA imaging-guided drug release. GEM induced tumor immunogenic cell death (ICD), and CpG ODN promoted an immune response to the antigens released by ICD, leading to long-term specific antitumor immunity. In addition, the PD-L1 aptamer relieved the inhibitory effect of the PD1/PD-L1 checkpoint on CD8⁺ T-cells and augmented the immunotherapeutic effect. The synergistic innate and adaptive immune responses enhanced the antitumor effect of ECNVs. In summary, this nanoplatform integrates local targeted photothermal therapy with extensive progressive chemotherapy and uses ICD to reshape the immune microenvironment for tumor ablation.

The SUMOylation inhibitor subasumstat potentiates rituximab activity by IFN1-dependent macrophage and NK cell stimulation

Small ubiquitin-like modifier (SUMO) is a member of a ubiquitin-like protein superfamily. SUMOylation is a reversible posttranslational modification that has been implicated in the regulation of various cellular processes including inflammatory responses and expression of type 1 interferons (IFN1). In this report, we have explored the activity of the selective small molecule SUMOylation inhibitor subasumstat (TAK-981) in promoting antitumor innate immune responses. We demonstrate that treatment with TAK-981 results in IFN1-dependent macrophage and natural killer (NK) cell activation, promoting macrophage phagocytosis and NK cell cytotoxicity in ex vivo assays. Furthermore, pretreatment with TAK-981 enhanced macrophage phagocytosis or NK cell cytotoxicity against CD20+ target cells in combination with the anti-CD20 antibody rituximab. In vivo studies demonstrated enhanced antitumor activity of TAK-981 and rituximab in CD20+ lymphoma xenograft models. Combination of TAK-981 with anti-CD38 antibody daratumumab also resulted in enhanced antitumor activity. TAK-981 is currently being studied in phase 1 clinical trials (#NCT03648372, #NCT04074330, #NCT04776018, and #NCT04381650; www.clinicaltrials.gov) for the treatment of patients with lymphomas and solid tumors.

Iron Activates cGAS-STING Signaling and Promotes Hepatic Inflammation

Iron deposition and chronic inflammation are associated with chronic liver diseases, such as alcoholic liver disease, nonalcoholic fatty liver disease, and chronic hepatitis B and C. However, the relationship between iron deposition and chronic inflammation in these diseases is still unclear. In the current study, we aimed to investigate the effect of iron on chronic inflammation in HepG2 cells and mice liver. We demonstrated that iron treatment enhanced the expression of cGAS, STING, and their downstream targets, including TBK1, IRF-3, and NF-κB in HepG2 cells and mice liver. We also found that treatment of HepG2 cells and mice with ferric ammonium citrate increased the expression of inflammatory cytokines, such as IFN-β. Finally, we found that genes involved in iron metabolism and the STING signaling pathway were up-regulated in liver cancer tissues, and the survival time of patients with high expression of these genes in tumor tissues was significantly shortened. These results suggest that iron overload may promote the progress of the chronic liver disease by activating cGAS-STING-mediated chronic inflammation, which provides a new idea for the development of drugs for the treatment of the chronic liver disease.

Polarized Macrophages in Periodontitis: Characteristics, Function, and Molecular Signaling

Periodontitis (PD) is a common chronic infectious disease. The local inflammatory response in the host may cause the destruction of supporting periodontal tissue. Macrophages play a variety of roles in PD, including regulatory and phagocytosis. Moreover, under the induction of different factors, macrophages polarize and form different functional phenotypes. Among them, M1-type macrophages with proinflammatory functions and M2-type macrophages with anti-inflammatory functions are the most representative, and both of them can regulate the tendency of the immune system to exert proinflammatory or anti-inflammatory functions. M1 and M2 macrophages are involved in the destructive and reparative stages of PD. Due to the complex microenvironment of PD, the dynamic development of PD, and various local mediators, increasing attention has been given to the study of macrophage polarization in PD. This review summarizes the role of macrophage polarization in the development of PD and its research progress.

Therapeutic Effects of Azithromycin on Spinal Cord Injury in Male Wistar Rats: A Role for Inflammatory Pathways

BACKGROUND

 Inflammatory responses, including macrophages/microglia imbalance, are associated with spinal cord injury (SCI) complications. Accumulating evidence also suggests an anti-inflammatory property of azithromycin (AZM).

MATERIAL AND METHODS

 Male Wistar rats were subjected to T9 vertebra laminectomy. SCI was induced by spinal cord compression at this level with an aneurysmal clip for 60 seconds. They were divided into three groups: the sham-operated group and two SCI treatment (normal saline as a vehicle control vs. AZM at 180 mg/kg/d intraperitoneally for 3 days postsurgery; first dose: 30 minutes after surgery) groups. Locomotor scaling and behavioral tests for neuropathic pain were evaluated and compared through a 28-day period. At the end of the study, tissue samples were taken to assess neuroinflammatory changes and neural demyelination using ELISA and histopathologic examinations, respectively. In addition, the proportion of M1/M2 macrophage polarization was assessed by using flow cytometry.

RESULTS

 Post-SCI AZM treatment (180 mg/kg/d for 3 days) significantly improved locomotion (p < 0.01) and decreased sensitivity to mechanical (p < 0.01) and thermal allodynia (p < 0.001). Moreover, there was a significant tumor necrosis factor-α (TNF-α) decline (p < 0.01) and interleukin-10 (IL-10) elevation (p < 0.01) in the spinal cord tissue of the AZM-treated group compared with the control groups 28 days post-SCI. AZM significantly improved neuroinflammation as evidenced by reduction of the M1 expression, elevation of M2 macrophages, and reduction of the M1/M2 ratio in both the dorsal root ganglion and the spinal cord tissue after SCI compared with controls (p < 0.01).

CONCLUSION

 AZM treatment can be considered a therapeutic agent for SCI, as it could reduce neuroinflammation and SCI sensory/locomotor complications.

Selective Induction of Cell Death in Human M1 Macrophages by Smac Mimetics Is Mediated by cIAP-2 and RIPK-1/3 through the Activation of mTORC

Inflammatory macrophages have been implicated in many diseases, including rheumatoid arthritis and inflammatory bowel disease. Therefore, targeting macrophage function and activation may represent a potential strategy to treat macrophage-associated diseases. We have previously shown that IFN-γ-induced differentiation of human M0 macrophages toward proinflammatory M1 state rendered them highly susceptible to the cytocidal effects of second mitochondria-derived activator of caspases mimetics (SMs), antagonist of the inhibitors of apoptosis proteins (IAPs), whereas M0 and anti-inflammatory M2c macrophages were resistant. In this study, we investigated the mechanism governing SM-induced cell death during differentiation into M1 macrophages and in polarized M1 macrophages. IFN-γ stimulation conferred on M0 macrophages the sensitivity to SM-induced cell death through the Jak/STAT, IFN regulatory factor-1, and mammalian target of rapamycin complex-1 (mTORC-1)/ribosomal protein S6 kinase pathways. Interestingly, mTORC-1 regulated SM-induced cell death independent of M1 differentiation. In contrast, SM-induced cell death in polarized M1 macrophages is regulated by the mTORC-2 pathway. Moreover, SM-induced cell death is regulated by cellular IAP (cIAP)-2, receptor-interacting protein kinase (RIPK)-1, and RIPK-3 degradation through mTORC activation during differentiation into M1 macrophages and in polarized M1 macrophages. In contrast to cancer cell lines, SM-induced cell death in M1 macrophages is independent of endogenously produced TNF-α, as well as the NF-κB pathway. Collectively, selective induction of cell death in human M1 macrophages by SMs may be mediated by cIAP-2, RIPK-1, and RIPK-3 degradation through mTORC activation. Moreover, blocking cIAP-1/2, mTORC, or IFN regulatory factor-1 may represent a promising therapeutic strategy to control M1-associated diseases.

Infiltration by CXCL10 Secreting Macrophages Is Associated With Antitumor Immunity and Response to Therapy in Ovarian Cancer Subtypes

Ovarian carcinomas (OCs) are poorly immunogenic and immune checkpoint inhibitors (ICIs) have offered a modest benefit. In this study, high CD3⁺ T-cells and CD163⁺ tumor-associated macrophages (TAMs) densities identify a subgroup of immune infiltrated high-grade serous carcinomas (HGSCs) with better outcomes and superior response to platinum-based therapies. On the contrary, in most clear cell carcinomas (CCCs) showing poor prognosis and refractory to platinum, a high TAM density is associated with low T cell frequency. Immune infiltrated HGSC are characterized by the 30-genes signature (OC-IS³⁰) covering immune activation and IFNγ polarization and predicting good prognosis (n = 312, TCGA). Immune infiltrated HGSC contain CXCL10 producing M1-type TAM (IRF1⁺pSTAT1Y701⁺) in close proximity to T-cells. A fraction of these M1-type TAM also co-expresses TREM2. M1-polarized TAM were barely detectable in T-cell poor CCC, but identifiable across various immunogenic human cancers. Single cell RNA sequencing data confirm the existence of a tumor-infiltrating CXCL10⁺IRF1⁺STAT1⁺ M1-type TAM overexpressing antigen processing and presentation gene programs. Overall, this study highlights the clinical relevance of the CXCL10⁺IRF1⁺STAT1⁺ macrophage subset as biomarker for intratumoral T-cell activation and therefore offers a new tool to select patients more likely to respond to T-cell or macrophage-targeted immunotherapies.

Ivermectin-functionalized multiwall carbon nanotube enhanced the locomotor activity and neuropathic pain by modulating M1/M2 macrophage and decrease oxidative stress in rat model of spinal cord injury

Since the inflammation and oxidative stress is the main pathophysiological pathway of neural damage in spinal cord injury (SCI), we tried to evaluate the role of ivermectin (IVM) combined with multi-walled carbon nanotube (MWCNT) in the treatment settings of SCI and its underlying mechanism. Wistar rats with T9 vertebra laminectomy in five groups of: sham-operated, vehicle, IVM (0.1 mg/kg), IVM-MWCNT (0.1 mg/kg), and minocycline (90 mg/kg) were used. We evaluated the locomotor scaling and other behavioral tests for neuropathic pain. Also, tissue samples were obtained to evaluate the expression of M1 and M2 macrophage marker, concentration of TNF-α, IL-1β, and IL-1, and oxidative stress level to assess neuroinflammatory changes. Both IVM and IVM-MWCNT after induction of SCI significantly enhanced the experimental tasks' outcomes, including locomotion and neuropathic tests. Also, decreasing in pro-inflammatory cytokines including TNF-α, IL-1β, and IL-1 in the spinal cord and dorsal root ganglion tissues was also notable in both IVM and IVM-MWCNT-treated groups 28 days after induction of SCI in compared to the vehicle-treated SCI group. Both IVM and IVM-MWCNT significantly decreased oxidative stress, induced by SCI, based on the results of ROS and NADPH activity. IVM-MWCNT-treated animals indicated better outcome in every previous experiment in comparison to IVM-treated animals. The effectiveness of IVM-MWCNT was similar to minocycline treatment in all experimental task (as positive control group). IVM-MWCNT might be a novel treatment in spinal cord injury, which could act through decreasing the oxidative stress and increase the polarization of M1 in comparison to M2 macrophages.

How Macrophages Become Transcriptionally Dysregulated: A Hidden Impact of Antitumor Therapy

Tumor-associated macrophages (TAMs) are the essential components of the tumor microenvironment. TAMs originate from blood monocytes and undergo pro- or anti-inflammatory polarization during their life span within the tumor. The balance between macrophage functional populations and the efficacy of their antitumor activities rely on the transcription factors such as STAT1, NF-κB, IRF, and others. These molecular tools are of primary importance, as they contribute to the tumor adaptations and resistance to radio- and chemotherapy and can become important biomarkers for theranostics. Herein, we describe the major transcriptional mechanisms specific for TAM, as well as how radio- and chemotherapy can impact gene transcription and functionality of macrophages, and what are the consequences of the TAM-tumor cooperation.

Super enhancer-mediated transcription of miR146a-5p drives M2 polarization during Leishmania donovani infection

The outcome of Leishmania donovani infection depends upon the dynamic interchanges between M1 and M2 macrophages. Information of the involvement of microRNAs (miRNAs) and epigenetic modifiers in regulating macrophage plasticity during L. donovani infection is still elusive. Differential expression analysis of polarization-regulating miRNAs, revealed significant enrichment of miR146a-5p during Leishmania donovani infection. A sustained enrichment of miR146a-5p was observed in both infected bone marrow derived macrophages (BMDMs) and BALB/c mice organs. We found involvement of miR146a-5p in phagocytosis and survivability of parasites. Moreover, miR146a-5pgot enriched in interleukin 4- stimulated BMDMs, indicating its possible involvement in M2 polarization. Upon transfecting BMDMs with miRVANA anti-146a oligos, M2 markers (CCR7, YM-1, FIZZ-1, arginase-1, IL10 and IL4) and transcription factors (p-STAT6 and c/EBPβ) got depleted with concomitant augmentation of M1-polarizing transcription factors (p-STAT1, AP1 and IRF-1), miR146a target genes (TRAF6 and IRAK1), M1 cytokines (IL12 and TNFα), iNOS, nitric oxide, and nuclear translocation of phospho p-65 subunit. Neutralization of intracellular mature miR146a-5p pool in infected BALB/c mice lower organ parasite burden and expressions of M2 markers and IL10 with enrichment of M1 markers like iNOS and IL12. Additionally, we explored the novel role of super enhancer (SE), a cis-acting regulatory component, to enrich miR146a-5p expression during infection. Enhanced expression and nuclear retention of SE components like BET bromodomain 4 (BRD4) and p300 were found in infected BMDMs. Upon silencing BRD4, expressions of miR146a-5p and M2 markers were down regulated and TRAF6, IRAK1 and iNOS levels increased. STRING V.11 based predication and immune precipitation confirmed the strong interaction amongst BRD4, p300 and RNA pol II (RpbI). Chromatin immune precipitation studies suggested the recruitment of BRD4 at the enhancer loci of miR146a-5p gene during infection. Altogether, our findings revealed a novel role of BRD4/p300-depdendent super-enhancer in regulating miR146a expression during L. donovani infection which in turn mediates M2 polarization and immune-suppression.

Visceral leishmaniasis (VL), caused by protozoan parasites Leishmania donovani, is the most severe form of leishmaniasis and is highly lethal if left untreated. Major obstacle for successful therapy of VL originates from the life-long immune-suppression triggered in the post kala-azar dermal leishmaniasis (PKDL) patients during infection. Identification of molecular principles behind such immune-suppression will add success in VL therapeutics. L. donovani hijacks the host macrophages and converts them from pro-inflammatory M1 to immune-suppressive M2 type, which allows successful infection establishment. Herein, we explored the indispensable role of miRNA-146a-5p in conversion of M1 to M2 type during infection. Both in vitro and in vivo miRNA silencing established miR146a-5p as an imperative negative regulator ofM1 polarization. Computational analysis as well as immune precipitation based experiments authenticated that L. donovani induces super enhancer complex mediated transcriptional upregulation of miR146a-5p. BET bromodomain protein 4 (BRD4) forms this SE complex along with p300 histone acetyl transferase and RNA pol II. Silencing of BRD4 significantly abrogated miR146a-5p mediated M2 polarization. In short, our current findings established a previously unrecognized role of BRD4-depdendent super enhancers in orchestrating persistent transcription of macrophage miR146a-5p which in turn promotes M2 polarization during L. donovani infection.

P21 activated kinase-1 (PAK1) in macrophages is required for promotion of Th17 cell response during helminth infection

CD4⁺T cells differentiate into distinct functional effector and inhibitory subsets are facilitated by distinct cytokine cues present at the time of antigen recognition. Maintaining a balance between T helper 17 (Th17) and regulatory T (Treg) cells are critical for the control of the immunopathogenesis of liver diseases. Here, by using the mouse model of helminth Schistosoma japonicum (Sjaponicum) infection, we show that the hepatic mRNA levels of P21‐activated kinase 1 (PAK1), a key regulator of the actin cytoskeleton, adhesion and cell motility, are significantly increased and associated with the development of liver pathology during Sjaponicum infection. In addition, PAK1‐deficient mice are prone to suppression of Th17 cell responses but increased Treg cells. Furthermore, PAK1 enhances macrophage activation through promoting IRF1 nuclear translocation in an NF‐κB‐dependent pathway, resulting in promoting Th17 cell differentiation through inducing IL‐6 production. These findings highlight the importance of PAK1 in macrophages fate determination and suggest that PAK1/IRF1 axis‐dependent immunomodulation can ameliorate certain T cell–based immune pathologies.

Reactive Oxygen Species and Inflammatory Responses of Macrophages to Substrates with Physiological Stiffness

Macrophages play essential roles in innate immunity and their functions can be activated by different signals at pathological sites. Concerning changes in the rigidity of the microenvironment as a disease progresses, the influence of stiffened substrates on macrophage physiology remains elusive. In this study, to evaluate the effect of stiffened substrates on macrophages, we used J774A.1 cells as the macrophage model to investigate its mechanoinflammation responses using engineered polymeric substrates with various physiological rigidities (approximately 0.6 to 100 kPa). Under lipopolysaccharide (LPS) and adenosine triphosphate (ATP) stress, approximately 4-fold higher cytoplasmic reactive oxygen species (ROS) were triggered in cells on the softer substrate, compared with cells on the stiff substrates. The enhanced ROS response was found to be regulated mainly by NADPH oxidase. Moreover, mitochondrial ROS (mtROS), a crucial intracellular ROS source, are produced in response to substrate rigidity. The results showed higher mtROS production when cells were grown on a soft substrate with LPS/ATP stimuli, and the mechano-mtROS alteration was eliminated by Rho kinase inhibitor Y-27632. We suggest that substrate rigidity can coincide with LPS/ATP in regulating the ROS generation of macrophages. As a result of the pivotal role of ROS in regulating inflammation, increased NLRP-3 inflammasome formation and higher NO secretion (an approximately 300% increase) were observed with macrophages grown on soft substrates. Although no substantial genomic distinction was identified in our experiments, based on the phenotypic and functional results, softer substrates prime macrophages toward the proinflammatory (M1)-like phenotype. In summary, this study demonstrated the mechanosensitive inflammatory response of macrophages and the alteration of ROS, as secondary inflammation signals, may contribute to the functional status of macrophages. These findings not only provide an alternative interpretation of the functional transitions of macrophages influenced by substrate rigidity but may also support the manipulation of the inflammatory responses of macrophages via physical microenvironment modifications.

miR-130b-3p regulates M1 macrophage polarization via targeting IRF1

Polarized macrophages can be broadly classified into classically activated macrophages (M1) and alternatively activated macrophages (M2) in response to the microenvironment signals. Interferon regulatory factor 1 (IRF1) has been demonstrated to play a critical role in macrophage polarization. However, the mechanisms underlying the regulation of IRF1 expression in macrophage polarization still remain unclear. In this study, IRF1 expression was significantly increased in interferon-γ (IFN-γ) and lipopolysaccharide (LPS)-treated RAW264.7 cells. Moreover, miR-130b-3p was decreased and negatively associated with Irf1 in M1 macrophages. miR-130b-3p repressed M1 polarization by inhibiting IRF1 and subsequently reducing the levels of the targets of IRF1, C-C motif chemokine ligand 5 (CCL5), C-X-C motif chemokine ligand 10 (CXCL10), inducible NO synthase (iNOS), and tumor necrosis factor (TNF). Consistent with these data, overexpressed miR-130b-3p in LPS-treated mice suppressed M1 macrophage polarization in lung macrophages and peritoneal macrophages by inhibiting Irf1 expression and alleviated the inflammation in mouse lung tissues. Furthermore, the predicted binding site between the Irf1 messenger RNA 3'-untranslated region (3'-UTR) and miR-130b-3p was confirmed by the dual-luciferase reporter assay. In conclusion, our research gave the first evidence that miR-130b-3p affected the polarization of M1 macrophages by directly inhibiting Irf1. The miR-130b-3p/IRF1 pathway may be a potential target for regulating macrophage polarization.

miR-106b-5p Inhibits IRF1/IFN-β Signaling to Promote M2 Macrophage Polarization of Glioblastoma

Purpose

The microRNA (miRNA) profile changes in the tumor-associated macrophages. However, the role of miR-106b-5p in the glioblastoma-associated macrophages is poorly understood.

Materials and Methods

In our study, miR-106b-5p and M2 macrophage markers were detected by qRT-PCR and Western blotting in THP1 cells, with the conditioned medium from U251 cells or M2 macrophages in response to IL-4 stimulation and M1 macrophages stimulated by LPS and IFN-γ. IFN regulatory factor (IRF1) was identified as a target of miR-106b-5p in the glioma infiltrating macrophages by luciferase reporter assay. The molecular mechanisms involved in the miR-106b-5p-mediated regulation of M2 polarization were clarified by shRNA knockdown assay.

Results

Our results showed miR-106b-5p expression was upregulated in glioma-infiltrating macrophages. miR-106b-5p regulated M2 polarization of glioma infiltrating macrophages and enhanced the growth of glioma-infiltrating macrophages. IRF1 was identified as a target of miR-106b-5p. Furthermore, miR-106b-5p inhibited IRF1 expression by targeting IRF1/IFN-β pathway to promote M2 polarization of macrophages.

Conclusion

miR-106b-5p may inhibit IRF1/IFN-β signaling to promote M2 macrophage polarization of glioblastoma, and it may become a novel target for the treatment of glioblastoma.

The emerging landscape of circular RNAs in immunity: breakthroughs and challenges

Circular RNAs (circRNAs) are covalently linked RNAs that exhibit individual strand with a closed-loop framework compared with a conserving, steady and abundant linear counterpart. In recent years, as high-throughput sequencing advancement has been developing, functional circRNAs have been increasingly recognized, and more extensive analyses expounded their effect on different diseases. However, the study on the function of circRNAs in the immune system remains insufficient. This study discusses the basic principles of circRNAs regulation and the systems involved in physiology-related and pathology-related processes. The effect of circRNAs on immune regulation is elucidated. The ongoing development of circRNAs and basic immunology has multiplied their potential in treating diseases. Such perspective will summarize the status and effect of circRNAs on various immune cells in cancer, autoimmune diseases and infections. Moreover, this study will primarily expound the system of circRNAs in T lymphocytes, macrophages and other immune cells, which creates a novel perspective and lay a theoretical basis for treating diseases.

SHP-2 and PD-L1 Inhibition Combined with Radiotherapy Enhances Systemic Antitumor Effects in an Anti-PD-1-Resistant Model of Non-Small Cell Lung Cancer

Immune checkpoint inhibitors, such as anti-PD-1/PD-L1, have emerged as promising therapies for advanced non-small cell lung cancer (NSCLC). However, approximately 80% of patients do not respond to immunotherapy given alone because of intrinsic or acquired resistance. Radiotherapy (XRT) can overcome PD-1 resistance and improve treatment outcomes, but its efficacy remains suboptimal. The tyrosine phosphatase SHP-2, expressed in some cancers and in immune cells, has been shown to negatively affect antitumor immunity. Our hypothesis was that SHP-2 inhibition in combination with anti-PD-L1 would enhance immune-mediated responses to XRT and synergistically boost antitumor effects in an anti-PD-1-resistant mouse model. We treated 129Sv/Ev mice with anti-PD-1-resistant 344SQ NSCLC adenocarcinoma with oral SHP099 (a SHP-2 inhibitor) combined with XRT and intraperitoneal anti-PD-L1. Primary tumors were treated with XRT (three fractions of 12 Gy each), whereas abscopal (out-of-field) tumors were observed but not treated. XRT in combination with SHP099 and anti-PD-L1 promoted local and abscopal responses, reduced lung metastases, and improved mouse survival. XRT also increased SHP-2⁺ M1 tumor-associated macrophages in abscopal tumors (P = 0.019). The addition of SHP099 also associated with a higher M1/M2 ratio, greater numbers of CD8⁺ T cells, and fewer regulatory T cells. This triple-combination therapy had strong antitumor effects in a mouse model of anti-PD-1-resistant NSCLC and may be a novel therapeutic approach for anti-PD-1-resistant NSCLC in patients.

Modulation of Wnt/β-catenin signaling in IL-17A-mediated macrophage polarization of RAW264.7 cells

Macrophages play pivotal roles in host defense and immune homeostasis, which have two major functional polarization states, the classically activated M1 and the alternatively activated M2. Interleukin (IL)-17A is an immune modulator able to shape macrophage phenotypes. Wnt/β-catenin is a developmental signaling pathway that plays crucial roles in morphogenesis and tissue homeostasis, which has also been recently demonstrated playing roles in immune regulation. A growing amount of evidence suggests that both Wnt and IL-17A signaling are involved in macrophage polarization. However, their interaction in macrophage polarization remains elusive. The aim of present study was to explore impacts of Wnt/β-catenin on IL-17A-mediated macrophage M1/M2 polarization in murine monocyte/macrophage-like cell line RAW264.7. Results revealed that IL-17A activated Wnt/β-catenin signaling and induced macrophage M1 polarization, but inhibited M2 polarization. In contrast, the activation of Wnt/β-catenin signaling led to the inhibition of M1 macrophage polarization but the promotion of M2 polarization. Importantly, the activation of Wnt/β-catenin also showed abilities to inhibit the IL-17A-induced M1 macrophage polarization while diminishing the IL-17A-inhibited M2 polarization. Molecular analysis further uncovered that the JAK/STAT signaling pathway was involved in the interaction of Wnt/β-catenin and IL-17A in the modulation of macrophage polarization. These results suggested that the Wnt/β-catenin signaling modulated IL-17A-altered macrophage polarization in part by regulating the JAK/STAT signaling pathway. This study thus revealed a novel function of Wnt/β-catenin signaling in regulating IL-17A-altered macrophage polarization.

MiR-103 protects from recurrent spontaneous abortion via inhibiting STAT1 mediated M1 macrophage polarization

Recurrent spontaneous abortion (RSA) is a common complication of early pregnancy. Excessive M1 macrophage was found to be involved in RSA, but the underlying mechanisms remains unclear. MicroRNAs play critical roles in RSA as well as the polarization of macrophages; however, the regulatory effect of miRNAs on M1 differentiation in RSA has not been fully investigated. In this study, miRNA microarray assay revealed that miR-103 was significantly decreased in RAW264.7-derived M1 macrophages upon IFNγ and LPS stimulation. Quantitative real-time polymerase chain reaction (qRT-PCR) analysis showed that in RSA patients, miR-103 expression was decreased substantially, and negatively correlated with that of STAT1. Moreover, down-regulation of miR-103 could sensitively discriminate RSA patients from normal pregnancies (NP) subjects. Experiments in vitro showed that overexpression of miR-103 suppressed M1 polarization by inhibiting STAT1/IRF1 signaling pathway and vice versa. miR-103 regulated STAT1 expression by direct binding to its 3'-UTR. Moreover, our in vivo study demonstrated that overexpressed miR-103 could reduce mice embryo resorption and M1 polarization effectively. Overall, the results suggested that decreased miR-103 was involved in RSA by increasing M1 macrophage polarization via promoting STAT1/IRF1 signaling pathway. miR-103 may be explored as a promising diagnostic marker and therapeutic target for RSA.

IRF1 association with tumor immune microenvironment and use as a diagnostic biomarker for colorectal cancer recurrence

Colorectal cancer (CRC) is considered to be one of the most lethal cancer types globally, and its recurrence is a major treatment challenge. Identifying the factors involved when determining the risk of CRC recurrence is required to improve personalized therapy for patients with CRC. Based on the GSE39582 dataset, the present study demonstrated that a higher ratio of M1 macrophages and activated memory CD4+ T cells indicated a better recurrence-free survival (RFS) time for CRC, using CIBERSORT and Pearson's correlation analysis. Through weighted correlation network analysis (WGCNA), an immune-associated module was identified that was significantly positively correlated with the ratio of M1 macrophages and activated memory CD4+ T cells. In this module, using WGCNA and a protein-protein interaction network, interferon regulatory factor 1 (IRF1), chemokine ligand 5, ubiquitin/ISG15-conjugating enzyme E2 L6, guanylate binding protein 1 and interleukin 2 receptor subunit beta were identified as hub genes. Among these genes, univariate Cox and multivariate Cox analysis revealed that IRF1 may be a potential diagnostic biomarker for RFS in patients with CRC. This was further validated using The Cancer Genome Atlas data. Gene set enrichment analysis demonstrated that IRF1 influenced the genes and pathways that are associated with immune cell recruitment and activation. Additionally, the DNA methylation of cg27587780 and cg15375424 CpG sites in the IRF1 gene region was indicated to be negatively correlated with IRF1 mRNA expression and positively correlated with the recurrence of CRC. Collectively, the results of the present study demonstrated that IRF1 may be a potential diagnostic biomarker for RFS in patients with CRC.

Interferon-β Plays a Detrimental Role in Experimental Traumatic Brain Injury by Enhancing Neuroinflammation That Drives Chronic Neurodegeneration

DNA damage and type I interferons (IFNs) contribute to inflammatory responses after traumatic brain injury (TBI). TBI-induced activation of microglia and peripherally-derived inflammatory macrophages may lead to tissue damage and neurological deficits. Here, we investigated the role of IFN-β in secondary injury after TBI using a controlled cortical impact model in adult male IFN-β-deficient (IFN-β^-/-) mice and assessed post-traumatic neuroinflammatory responses, neuropathology, and long-term functional recovery. TBI increased expression of DNA sensors cyclic GMP-AMP synthase and stimulator of interferon genes in wild-type (WT) mice. IFN-β and other IFN-related and neuroinflammatory genes were also upregulated early and persistently after TBI. TBI increased expression of proinflammatory mediators in the cortex and hippocampus of WT mice, whereas levels were mitigated in IFN-β^-/- mice. Moreover, long-term microglia activation, motor, and cognitive function impairments were decreased in IFN-β^-/- TBI mice compared with their injured WT counterparts; improved neurological recovery was associated with reduced lesion volume and hippocampal neurodegeneration in IFN-β^-/- mice. Continuous central administration of a neutralizing antibody to the IFN-α/β receptor (IFNAR) for 3 d, beginning 30 min post-injury, reversed early cognitive impairments in TBI mice and led to transient improvements in motor function. However, anti-IFNAR treatment did not improve long-term functional recovery or decrease TBI neuropathology at 28 d post-injury. In summary, TBI induces a robust neuroinflammatory response that is associated with increased expression of IFN-β and other IFN-related genes. Inhibition of IFN-β reduces post-traumatic neuroinflammation and neurodegeneration, resulting in improved neurological recovery. Thus, IFN-β may be a potential therapeutic target for TBI.SIGNIFICANCE STATEMENT TBI frequently causes long-term neurological and psychiatric changes in head injury patients. TBI-induced secondary injury processes including persistent neuroinflammation evolve over time and can contribute to chronic neurological impairments. The present study demonstrates that TBI is followed by robust activation of type I IFN pathways, which have been implicated in microglial-associated neuroinflammation and chronic neurodegeneration. We examined the effects of genetic or pharmacological inhibition of IFN-β, a key component of type I IFN mechanisms to address its role in TBI pathophysiology. Inhibition of IFN-β signaling resulted in reduced neuroinflammation, attenuated neurobehavioral deficits, and limited tissue loss long after TBI. These preclinical findings suggest that IFN-β may be a potential therapeutic target for TBI.

IFN Regulatory Factor 1 Mediates Macrophage Pyroptosis Induced by Oxidized Low-Density Lipoprotein in Patients with Acute Coronary Syndrome

Background

Atherosclerosis (AS) is recognized as a chronic inflammatory disease. It is caused by the interaction between inflammatory cells such as macrophages, dendritic cells, and lipoproteins. Evidence has revealed that macrophage pyroptosis in lesion contributes to the formation of the necrotic core and thinning of the fibrous cap, which plays crucial roles in the onset of acute coronary syndrome (ACS). IFN regulatory factor 1 (IRF-1) is a pleiotropic transcription factor involved in various immune processes and cell death. We propose that IRF-1 may be implicated in macrophage pyroptosis in the pathogenesis of AS and ACS.

Methods

Patients with stable angina, unstable angina, acute myocardial infarction, and clinical presentation of chest pain were enrolled. The expression of IRF-1 in human PBMC-derived macrophages was analyzed. Then, overexpression and inhibition of IRF-1 was performed in macrophages from patients with ACS to explore the possible role and mechanism of IRF-1 involvement in macrophage pyroptosis.

Results

The expression of IRF-1 in macrophages was upregulated in ACS patients. The overexpression or inhibition of IRF-1 effectively modulated caspase-1 activation, as well as macrophage lysis, expression of gasdermin D-N (GSDMD-N), production of IL-1β and IL-18, and activation of NLRP3-ASC inflammasome, which were all inhibited by caspase-1 inhibitor. Further experiments revealed that pyroptosis and the downstream inflammatory response in AS induced by IRF-1 is a process that is dependent on reactive oxygen species (ROS) generation.

Conclusion

Our observations suggest that IRF-1 potently activates ox-LDL-induced macrophage pyroptosis and may play an important role in AS and ACS.

Balancing STAT Activity as a Therapeutic Strategy

Driven by dysregulated IL-6 family member cytokine signaling in the tumor microenvironment (TME), aberrant signal transducer and activator of transcription (STAT3) and (STAT5) activation have been identified as key contributors to tumorigenesis. Following transformation, persistent STAT3 activation drives the emergence of mesenchymal/cancer-stem cell (CSC) properties, important determinants of metastatic potential and therapy failure. Moreover, STAT3 signaling within tumor-associated macrophages and neutrophils drives secretion of factors that facilitate metastasis and suppress immune cell function. Persistent STAT5 activation is responsible for cancer cell maintenance through suppression of apoptosis and tumor suppressor signaling. Furthermore, STAT5-mediated CD4+/CD25+ regulatory T cells (T_regs) have been implicated in suppression of immunosurveillance. We discuss these roles for STAT3 and STAT5, and weigh the attractiveness of different modes of targeting each cancer therapy. Moreover, we discuss how anti-tumorigenic STATs, including STAT1 and STAT2, may be leveraged to suppress the pro-tumorigenic functions of STAT3/STAT5 signaling.

The Role of Metabolic Remodeling in Macrophage Polarization and Its Effect on Skeletal Muscle Regeneration

Significance: Macrophages are crucial for tissue homeostasis. Based on their activation, they might display classical/M1 or alternative/M2 phenotypes. M1 macrophages produce pro-inflammatory cytokines, reactive oxygen species (ROS), and nitric oxide (NO). M2 macrophages upregulate arginase-1 and reduce NO and ROS levels; they also release anti-inflammatory cytokines, growth factors, and polyamines, thus promoting angiogenesis and tissue healing. Moreover, M1 and M2 display key metabolic differences; M1 polarization is characterized by an enhancement in glycolysis and in the pentose phosphate pathway (PPP) along with a decreased oxidative phosphorylation (OxPhos), whereas M2 are characterized by an efficient OxPhos and reduced PPP. Recent Advances: The glutamine-related metabolism has been discovered as crucial for M2 polarization. Vice versa, flux discontinuities in the Krebs cycle are considered additional M1 features; they lead to increased levels of immunoresponsive gene 1 and itaconic acid, to isocitrate dehydrogenase 1-downregulation and to succinate, citrate, and isocitrate over-expression. Critical Issues: A macrophage classification problem, particularly in vivo, originating from a gap in the knowledge of the several intermediate polarization statuses between the M1 and M2 extremes, characterizes this field. Moreover, the detailed features of metabolic reprogramming crucial for macrophage polarization are largely unknown; in particular, the role of β-oxidation is highly controversial. Future Directions: Manipulating the metabolism to redirect macrophage polarization might be useful in various pathologies, including an efficient skeletal muscle regeneration. Unraveling the complexity pertaining to metabolic signatures that are specific for the different macrophage subsets is crucial for identifying new compounds that are able to trigger macrophage polarization and that might be used for therapeutical purposes.

Myosin 1F Regulates M1-Polarization by Stimulating Intercellular Adhesion in Macrophages

Intestinal macrophages are highly mobile cells with extraordinary plasticity and actively contribute to cytokine-mediated epithelial cell damage. The mechanisms triggering macrophage polarization into a proinflammatory phenotype are unknown. Here, we report that during inflammation macrophages enhance its intercellular adhesion properties in order to acquire a M1-phenotype. Using in vitro and in vivo models we demonstrate that intercellular adhesion is mediated by integrin-αVβ3 and relies in the presence of the unconventional class I myosin 1F (Myo1F). Intercellular adhesion mediated by αVβ3 stimulates M1-like phenotype in macrophages through hyperactivation of STAT1 and STAT3 downstream of ILK/Akt/mTOR signaling. Inhibition of integrin-αVβ3, Akt/mTOR, or lack of Myo1F attenuated the commitment of macrophages into a pro-inflammatory phenotype. In a model of colitis, Myo1F deficiency strongly reduces the secretion of proinflammatory cytokines, decreases epithelial damage, ameliorates disease activity, and enhances tissue repair. Together our findings uncover an unknown role for Myo1F as part of the machinery that regulates intercellular adhesion and polarization in macrophages.

Macrophage Polarization: Different Gene Signatures in M1(LPS+) vs. Classically and M2(LPS-) vs. Alternatively Activated Macrophages

Macrophages are found in tissues, body cavities, and mucosal surfaces. Most tissue macrophages are seeded in the early embryo before definitive hematopoiesis is established. Others are derived from blood monocytes. The macrophage lineage diversification and plasticity are key aspects of their functionality. Macrophages can also be generated from monocytes in vitro and undergo classical (LPS+IFN-γ) or alternative (IL-4) activation. In vivo, macrophages with different polarization and different activation markers coexist in tissues. Certain mouse strains preferentially promote T-helper-1 (Th1) responses and others Th2 responses. Their macrophages preferentially induce iNOS or arginase and have been called M1 and M2, respectively. In many publications, M1 and classically activated and M2 and alternatively activated are used interchangeably. We tested whether this is justified by comparing the gene lists positively [M1(=LPS+)] or negatively [M2(=LPS-)] correlated with the ratio of IL-12 and arginase 1 in transcriptomes of LPS-treated peritoneal macrophages with in vitro classically (LPS, IFN-γ) vs. alternatively activated (IL-4) bone marrow derived macrophages, both from published datasets. Although there is some overlap between in vivo M1(=LPS+) and in vitro classically activated (LPS+IFN-γ) and in vivo M2(=LPS-) and in vitro alternatively activated macrophages, many more genes are regulated in opposite or unrelated ways. Thus, M1(=LPS+) macrophages are not equivalent to classically activated, and M2(=LPS-) macrophages are not equivalent to alternatively activated macrophages. This fundamental discrepancy explains why most surface markers identified on in vitro generated macrophages do not translate to the in vivo situation. Valid in vivo M1/M2 surface markers remain to be discovered.

IRF1 inhibits the proliferation and metastasis of colorectal cancer by suppressing the RAS-RAC1 pathway

Background

Interferon regulatory factor 1 (IRF1) plays a role in the immune response, cellular necrosis, DNA damage, and DNA repair, offering an attractive target for anticancer treatment. However, little is known about the role of IRF1 in the regulation of CRC progression.

Methods

Quantitative reverse transcription-PCR, Western blot, and immunohistochemistry were used to examine the expression level of IRF1; Cell Counting Kit-8, migration assay, and xenograft mouse models were used to examine the function of IRF1 in CRC cell lines; a ChIP assay was used to examine the binding between IRF1 and Ras association domain-containing protein 5 (RASSF5).

Results

IRF1 expression was lower in colorectal cancer (CRC) than in normal mucosa and the IRF1 expression level was inversely associated with CRC metastasis. In addition, IRF1 could inhibit CRC cell proliferation, migration, and metastasis in vivo and in vitro; IRF1 also induced cell cycle arrest but had no effect on cell apoptosis. IRF1 enhanced the expression of RASSF5 by increasing its promoter activity. Moreover, this study revealed a novel mechanism for inhibiting the RAS-RAC1 pathway by overexpression of RASSF5.

Conclusion

Altogether, the results indicate that IRF1, which promotes RASSF5 expression, suppresses CRC metastasis and proliferation possibly through downregulation of the RAS-RAC1 pathway.

Polysaccharides from Citrus grandis associate with luteolin relieves chronic pharyngitis by anti-inflammatory via suppressing NF-κB pathway and the polarization of M1 macrophages

Chronic pharyngitis is characterized as a common inflammation of the pharyngeal mucosa, and anti-inflammatory medications are the common treatment to relieve it. Polysacharides of Citrus grandis L. Osbeck (PCG) and luteolin have been reported to have anti-inflammatory activities. In this study, the protective effects of PCG and luteolin on chronic pharyngitis are evaluated and the underlying mechanisms are explored. PCG and luteolin are administrated to animal models with granuloma, ear edema and chronic pharyngitis and the effects of PCG and luteolin on disease severity are evaluated. We also evaluate the effects of PCG and luteolin on inflammatory cytokine production in macrophages stimulated with lipopolysaccharides (LPS)/interferon-gamma (IFN-γ) and detect the effects of PCG and luteolin on macrophage polarization. Finally, we evaluate the effects of PCG and luteolin on activations of LPS-induced downstream signaling pathways. PCG and luteolin alleviate the disease severity of granuloma, ear edema and chronic pharyngitis. PCG and luteolin suppress the productions of pro-inflammatory cytokines interlukin-6 (IL-6), interlukin-12 (IL-12) and tumor necrosis factor alpha (TNF-α) in macrophages. Luteolin promotes macrophage M2 polarization by enhancing expressions of arginase (Arg1) and mannose receptor C type 1 (Mrc1). PCG and luteolin suppress nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) activation and interferon regulatory factor 1 (IRF1), interferon regulatory factor 5 (IRF5) expression. PCG together with luteolin relieves chronic pharyngitis by anti-inflammatory via suppressing NF-κB pathway and the polarization of M1 macrophage.

The effects of CD14 and IL-27 on induction of endotoxin tolerance in human monocytes and macrophages

Upon repeated exposure to endotoxin or lipopolysaccharide (LPS), myeloid cells enter a refractory state called endotoxin tolerance as a homeostatic mechanism. In innate immune cells, LPS is recognized by co-receptors Toll-like receptor 4 (TLR4) and CD-14 to initiate an inflammatory response for subsequent cytokine production. One such cytokine, interleukin (IL)-27, is produced by myeloid cells in response to bacterial infection. In monocytes, IL-27 has proinflammatory functions such as up-regulating TLR4 expression for enhanced LPS-mediated cytokine production; alternatively, IL-27 induces inhibitory functions in activated macrophages. This study investigated the effects of IL-27 on the induction of endotoxin tolerance in models of human monocytes compared with macrophages. Our data demonstrate that IL-27 inhibits endotoxin tolerance by up-regulating cell surface TLR4 expression and soluble CD14 production to mediate stability of the surface LPS-TLR4-CD14 complex in THP-1 cells. In contrast, elevated basal expression of membrane-bound CD14 in phorbol 12-myristate 13-acetate (PMA)-THP-1 cells, primary monocytes, and primary macrophages may promote CD14-mediated endocytosis and be responsible for the preservation of an endotoxin-tolerized state in the presence of IL-27. Overall, the efficacy of IL-27 in inhibiting endotoxin tolerance in human THP-1 monocytes and PMA-THP-1 macrophages is affected by membrane-bound and soluble CD14 expression.

Pivotal role of innate myeloid cells in cerebral post-ischemic sterile inflammation

Inflammatory responses play a multifaceted role in regulating both disability and recovery after ischemic brain injury. In the acute phase of ischemic stroke, resident microglia elicit rapid inflammatory responses by the ischemic milieu. After disruption of the blood-brain barrier, peripheral-derived neutrophils and mononuclear phagocytes infiltrate into the ischemic brain. These infiltrating myeloid cells are activated by the endogenous alarming molecules released from dying brain cells. Inflammation after ischemic stroke thus typically consists of sterile inflammation triggered by innate immunity, which exacerbates the pathologies of ischemic stroke and worsens neurological prognosis. Infiltrating immune cells sustain the post-ischemic inflammation for several days; after this period, however, these cells take on a repairing function, phagocytosing inflammatory mediators and cellular debris. This time-specific polarization of immune cells in the ischemic brain is a potential novel therapeutic target. In this review, we summarize the current understanding of the phase-dependent role of innate myeloid cells in ischemic stroke and discuss the cellular and molecular mechanisms of their inflammatory or repairing polarization from a therapeutic perspective.

IRF5-mediated immune responses and its implications in immunological disorders

Transcription factors are gene regulators that activate or repress target genes. One family of the transcription factors that have been extensively studied for their crucial role in regulating gene network in the immune system is the interferon regulatory factors (IRFs). IRFs possess a novel turn-helix turn motif that recognizes a specific DNA consensus found in the promoters of many genes that are involved in immune responses. IRF5, a member of IRFs has recently gained much attention for its role in regulating inflammatory responses and autoimmune diseases. Here, we discuss the role of IRF5 in regulating immune cells functions and how the dysregulation of IRF5 contributes to the pathogenesis of immune disorders. We also review the latest findings of potential IRF5 inhibitors that modulate IRF5 activity in the effort of developing therapeutic approaches for treating inflammatory disorders.