Search Results (165)

The transcription factor IRF5 maintains macrophages in the pro-inflammatory M1 state. We assessed the effects of siRNA-mediated knockdown of Irf5 on murine bone marrow-derived macrophages (BMDM) in M0, M1 and M2 states. Knockdown of Irf5 in M1 macrophages made them phenotypically similar to M2 macrophages, which was reflected in the decreased expression of the M1 marker iNOS, increased expression of the M2 marker CD206, increased mitochondrial content and respective morphological changes. Interestingly, the M2 phenotype was also affected by the reduction in Irf5. Using atomic force microscopy (AFM), we showed that Irf5 knockdown increases plasma membrane roughness, particularly in M2 macrophages. AFM-based stiffness measurements indicated that Irf5 knockdown altered macrophage elasticity, potentially influencing their functional behavior. Our data suggest a complex role of IRF5 in macrophage polarization, supporting its dual role as a transcriptional activator and repressor both in M1 and M2 states, and highlight the importance of IRF5 in the maintenance of metabolic and functional properties of macrophages. Full article

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a continuum of hepatic pathological manifestations of the metabolic syndrome. Pathogenesis is not clearly understood despite recent progress, but Kupffer cells and bone marrow-derived macrophages (BMDMs) have a fundamental role. In this review, the multiple pathophysiological aspects of MASLD are presented, including genetics, insulin resistance, lipotoxicity, and inflammation. The participation of innate and adaptive immunity, as well as the implications of the recently described trained immunity, is presented. The interplay of the liver with the gut microbiota is also analyzed. A recent adipocentric theory and the various mechanisms of hepatocyte death are also described. The fundamental role of Kupffer cells and other liver macrophages is discussed in detail, including their extreme phenotypic plasticity in both the normal and the MASLD liver. The functional differentiation between pro-inflammatory and anti-inflammatory subpopulations and their protective or detrimental involvement is further described, including the participation of Kupffer cells and BMDMs in all aspects of MASLD pathogenesis. The role of macrophages in the development of advanced MASLD, including fibrosis and hepatocellular carcinoma, is analyzed and the lack of explanation for the transition from MASLD to MASH is recognized. Finally, current modalities of drug treatment are briefly presented and the effects of different drugs on macrophage polarization and functions are discussed. Full article

Tumor-associated macrophages (TAMs) are abundant in the tumor microenvironment (TME) and often adopt an M2-like immunosuppressive phenotype that promotes tumor growth. Reprogramming TAMs toward an M1-like pro-inflammatory state is an attractive therapeutic strategy. Tumor Treating Fields (TTFields), an FDA-approved, electric-field–based therapy, has recently been suggested to modulate immune responses in addition to its established anti-mitotic activity. Here, we investigated the direct effects of TTFields on macrophage activation and function. Murine bone marrow–derived macrophages (BMDMs) were polarized toward a pro-inflammatory M1-like phenotype or an anti-inflammatory M2-like phenotype and exposed to TTFields. TTFields rapidly activated guanine nucleotide exchange factor-H1 (GEF-H1), and downstream nuclear factor kappa B (NF-κB) and activator protein-1 (AP-1, via c-Jun N-terminal kinase [JNK]) signaling. Functionally, TTFields reprogrammed M2-like macrophages by increasing major histocompatibility complex class II (MHC-II) and cluster of differentiation 80 (CD80); reducing arginase-1 (Arg1); and elevating secretion of chemokine (C-X-C motif) ligand 1 (CXCL1), interleukin-6 (IL-6), IL-1β, and IL-12 subunit p70 (IL-12p70). In interferon gamma (IFN-γ)-primed macrophages, TTFields provided a secondary signal, driving myeloid differentiation primary response 88 (MyD88)-dependent expression of inducible nitric oxide synthase (iNOS). In vivo, TTFields reduced tumor burden in an orthotopic murine lung cancer model and increased iNOS expression in both M1-like and a subset of M2-like TAMs. These findings demonstrate that TTFields directly reprogram macrophages toward a pro-inflammatory phenotype, suggesting a novel immunomodulatory mechanism that may enhance anti-tumor immunity in the TME. Full article

Objectives: As a novel member of the interleukin(IL)-1 family, IL-38 has shown therapeutic effects in various chronic inflammatory diseases. However, its role and underlying mechanisms in cardiovascular diseases, particularly atherosclerosis, remain unclear. This study aimed to explore the effects of IL-38 on atherosclerosis progression and its mechanisms in regulating macrophage function during the atherosclerotic process. Methods: To evaluate the therapeutic potential of IL-38 in atherosclerosis, we performed histopathological examinations and biochemical analyses in vivo. In vitro, we used primary bone marrow-derived macrophages (BMDMs) stimulated with oxidized low-density lipoprotein (ox-LDL) to assess the anti-inflammatory effects of IL-38 and quantified its impact on ox-LDL-induced macrophage polarization. To further elucidate the specific mechanisms by which IL-38 regulates macrophage function, we conducted mRNA sequencing and validated downstream regulatory signaling pathways. Results: IL-38 exhibited therapeutic potential in atherosclerosis by reducing atherosclerotic plaque formation, modulating plaque composition, suppressing the production of proinflammatory cytokines within plaques, and potentially regulating macrophage cholesterol metabolism. Moreover, IL-38 exerted significant anti-inflammatory effects on macrophages both in vivo and in vitro. Notably, it inhibited the polarization of macrophages toward the proinflammatory M1-like phenotype in both settings. Additionally, IL-38 impeded the phosphorylation and nuclear translocation of p65 in BMDMs and reduced ox-LDL-induced macrophage apoptosis. Conclusion: IL-38 holds therapeutic potential for atherosclerosis, as it alleviates disease progression, inhibits macrophage polarization toward the M1-like phenotype, suppresses nuclear factor-κB (NF-κB) signaling activation, and reduces macrophage apoptosis. This study provides new insights into the anti-inflammatory mechanisms by which IL-38 mitigates atherosclerosis. Full article

KEAP1 negatively regulates the cytoprotective factor NRF2 and is commonly inactivated in lung cancer cells. Loss-of-function KEAP1 mutations in cancer cells contribute to NRF2 activation and tumor immune evasion through immunosuppression and drug resistance. Counterintuitively, treatment with synthetic oleanane triterpenoids, potent NRF2 activators, reduces the pre-clinical tumor burden. This suggests the functional target of these drugs in cancer models is not the cancer cells but another tumor immune microenvironment (TIME) cell population. The anti-tumor potential of cells within the TIME, particularly macrophages, is potentiated by triterpenoid treatment in cancers with wild-type KEAP1 status. As KEAP1-mutant cancers show reduced tumor immune responses, triterpenoid-mediated immune stimulation may particularly benefit these cases, but this has not been investigated. To characterize the immunomodulatory effects of triterpenoids in KEAP1-mutant lung cancer, we studied tumor-educated bone marrow-derived macrophages (TE-BMDMs) and lung cancer models treated with the triterpenoids CDDO-Me or omaveloxolone. RNA-sequencing of TE-BMDMs cultured in KEAP1 KO compared to WT cancer-conditioned media had enhanced tumor-promoting phenotypes, which reversed with CDDO-Me treatment. Similarly, subcutaneous KEAP1 KO tumors were larger and more immune-suppressed compared to WT tumors. Both CDDO-Me and omaveloxolone reduced the tumor burden and improved immune cell phenotypes within the TIME independent of KEAP1 mutational status. Full article

Sodium butyrate has been documented to support gut function and help control pathogens in the gastrointestinal tract. However, the precise mechanisms of dietary sodium butyrate’s control over enteric pathogens in chickens remain unclear. Our study demonstrated that priming chicken bone marrow-derived macrophages (BMDMs) or the HD11 cell line with 1 mM sodium butyrate significantly enhanced their antimicrobial capacity against key bacterial pathogens (Escherichia coli, Salmonella Typhimurium, Pseudomonas aeruginosa, and Staphylococcus aureus) in gentamicin protection assays (p < 0.05; ≥1 log reduction in CFU/mL). This in vitro enhancement was associated with increased production of reactive oxygen species (ROS), as detected by DCFH-DA assays, showing approximately a 30% increase in HD11 cells and a 12% increase in BMDMs. Butyrate priming was observed to result in autophagy activation, potentially through mTOR pathway inhibition, evidenced by changes in related gene expression using RT-qPCR assay and a 2.5-fold increase in GFP-LC3B accumulation. Supporting this, pharmacological inhibition of ROS using the ROS scavenger N-acetyl-L-cystine (NAC) or autophagy with chloroquine reduced the butyrate-enhanced bacterial clearance. Furthermore, the mTOR inhibitor rapamycin synergized with butyrate priming, whereas the mTOR activator L-leucine counteracted enhanced antimicrobial activity. These findings offer crucial insights for improving host defence against bacterial infections and developing novel therapeutic strategies in chickens. Full article

In the environment, the coexistence of microplastics (MPs) with other pollutants may either enhance or reduce the toxicity of MPs themselves or the co-occurring pollutants toward microalgae. This phenomenon is particularly notable when MPs interact with emerging pollutants, such as ultraviolet absorbers. This study investigates the single and combined exposure effects of ultraviolet absorber (Butyl methoxydibenzoylmethane, BMDM, 50 μg/L) and MPs (Polystyrene, PS, 10 mg/L, d = 1 μm) on Chlorella sp. with a stress duration of 7 days. The results showed that cell density, chlorophyll a (Chla) concentration, and physical properties of cell surface integrity were higher in the combined stress group compared to the BMDM single stress group. Furthermore, transcriptome sequencing analysis revealed that the number of differentially expressed genes (DEGs) in the combined exposure group (885 DEGs) was lower than in the single exposure groups (BMDM: 1870 DEGs and PS: 9109 DEGs). Transcriptomic profiling indicated that individual stressors of BMDM and PS disrupted 113 and 123 pathways, respectively, predominantly associated with protein synthesis and energy metabolism. Conversely, combined exposure significantly enriched 86 pathways, including ribosome function and oxidative phosphorylation, thereby manifesting an antagonistic effect. This study provides new insights into the effects of BMDM and PS on Chlorella sp. and offers valuable information for the risk assessment of multiple pollutants. Full article

The Salmonella enterica serovar Typhimurium (ST) mutant lacking the msbB gene (ΔmsbB) has been widely studied as a candidate for attenuated bacterial vectors in therapeutic applications. Deletion of msbB results in LPS with under-acylated lipid A, which lowers endotoxicity while maintaining structural integrity. This attenuation has traditionally been attributed to reduced TLR4 activation due to weaker interaction between the modified lipid A and TLR4. In our study, we confirmed that ΔmsbB ST was less lethal than wild-type (WT) ST in a mouse sepsis model. However, this difference persisted even in TLR4- and caspase-11-deficient mice, suggesting that LPS signaling is not the primary determinant of virulence. In vitro, bone marrow–derived macrophages (BMDMs) from TLR4- or caspase-11-deficient mice showed only modest reductions in ST-induced cell death and cytokine production. Importantly, ΔmsbB ST behaved similarly to WT ST in these assays, further indicating that LPS-mediated signaling is not central to the observed attenuation. Our previous studies showed that ST-induced mortality in mice is primarily mediated through NLRC4 activation. Using qPCR and immunoblotting, we found that expression of NLRC4 activators was diminished in the ΔmsbB strain. Additionally, the mutant exhibited increased outer membrane permeability—likely contributing to its heightened antibiotic sensitivity—and reduced motility due to lower flagellin protein levels. In summary, the attenuation of virulence observed in the ΔmsbB strain is not directly due to altered LPS–TLR4 interactions, but rather an indirect effect of diminished expression of virulence factors that activate the NLRC4 inflammasome. Full article

Toxoplasma gondii (T. gondii) infection during pregnancy can cause severe placental damage and fetal impairment. Although triggering the receptor expressed on myeloid cells 2 (Trem2) confers protection against T. gondii infection, the precise molecular mechanisms underlying this immunoregulatory role remain incompletely understood. Using a mouse model, this study identifies a novel Trem2-MICAL1-P-ERK axis in macrophages that protects against T. gondii-induced adverse pregnancy outcomes (APO). RNA-seq of Trem2-overexpressing macrophages revealed significant upregulation of 1857 genes, with MICAL1 among the most markedly altered, highlighting its potential role in Trem2-mediated signaling. Mechanistically, correlation analysis, molecular docking, fluorescence co-localization, and immunoprecipitation assays demonstrate that Trem2 directly interacts with MICAL1, which modulates downstream phosphorylated ERK (P-ERK) signaling. In a T. gondii-infected murine pregnancy model, genetic ablation of Trem2 exacerbated pathogen-induced suppression of MICAL1 and P-ERK, whereas macrophage-specific overexpression of Trem2-DAP12 restored this signaling axis. Conversely, MICAL1 overexpression rescued P-ERK activation but failed to regulate Trem2 expression. Further studies in bone marrow-derived macrophages (BMDMs) revealed that Trem2 deficiency potentiated the inhibitory effects of soluble T. gondii antigens (TgAg) on MICAL1 and P-ERK. These findings elucidate how T. gondii disrupts placental immunity through targeted suppression of Trem2-mediated signaling and establish the Trem2-MICAL1-P-ERK cascade as a core regulatory pathway in immune homeostasis during pregnancy. Full article

Acute lung injury (ALI) is a severe pulmonary disorder characterized by the disruption of the alveolar–capillary barrier, leading to impaired oxygenation and pulmonary edema. Current pharmacological interventions primarily involve the use of steroid drugs, oxygen radical scavengers, and bronchodilators. However, the therapeutic efficacy of these interventions remains inconsistent. Canthin-6-ones, a class of tryptophan-derived alkaloids, exhibit anti-inflammatory, antioxidant, and immunomodulatory properties. In this study, we synthesized a novel Canthin-6-one derivative, namely HCX3, and evaluated its potential beneficial effects and underlying mechanisms on ALI. Prior to the experimental study, network pharmacology analysis revealed that HCX3 may exert anti-inflammatory effects in the context of ALI through the regulation of multiple signaling pathways, including the NF-κB pathways. To validate these findings, Lipopolysaccharide (LPS) was employed to stimulate RAW 264.7 macrophages and bone marrow-derived macrophages (BMDMs) to construct cellular models of inflammatory response associated with ALI. Our data demonstrated that exposure to HCX3 significantly inhibited the transcription and the secretion of multiple pro-inflammatory mediators, including IL-1β, IL-6, and TNF-α, in a dose-dependent manner. Additionally, HCX3 reduced LPS-induced phosphorylation levels of p65 and IκB-α in macrophages, indicating an inhibitory effect of the compound on the activation of NF-κB signaling pathway. Collectively, our data suggest that HCX3 exhibits significant anti-inflammatory effects by inhibiting NF-κB-related signaling pathways, providing new insights for ALI treatment. Full article

Toll-like receptor 3 (TLR3) initiates antiviral and inflammatory responses exclusively through the adaptor protein TRIF (TIR-domain-containing adapter-inducing interferon-β). In contrast, MyD88 (myeloid differentiation primary response 88), a central adaptor for most other TLRs, is traditionally considered dispensable for TLR3 signaling. Here, we demonstrate that MyD88 directly contributes to TLR3-mediated NF-κB activation and cytokine production in macrophages. Bone marrow-derived macrophages (BMDMs) from MyD88 deficient mice exhibited significantly attenuated NF-κB activation in response to the TLR3 agonist polyinosinic–polycytidylic acid (poly(I:C)) compared to wild-type cells, as evidenced by the reduced phosphorylation of NF-κB p65 and IκBα, as well as IκBα degradation. Consistently, pro-inflammatory cytokine production, including IL-6, TNF-α, and IFN-β, was attenuated in MyD88-deficient BMDMs in vitro following stimulation by poly(I:C) or poly(A:U), another TLR3 agonist. Blood concentrations of IL-6, TNF-α, and IFN-β were significantly reduced in both TRIF-deficient mice and MyD88-deficient mice challenged by the i.p. injection of poly(I:C). Mechanistic analyses revealed that MyD88 physically associates with activated TLR3 upon poly(I:C) stimulation, and that TLR3 engagement triggered MyD88 oligomerization, which was absent in TLR3 or TRIF deficient macrophages. Our findings highlight a previously unrecognized dual-adaptor mechanism for TLR3, wherein MyD88 recruitment amplifies NF-κB signaling dynamics by bridging TLR3 to the canonical NF-κB activation cascade and robust cytokine induction. This study expands the paradigm of TLR3 signaling by establishing MyD88 as a direct contributor to TLR3-driven innate immune responses, offering new insight into cross-talk between MyD88-dependent and -independent pathways. Full article

Genetic engineering of macrophages, particularly for chimeric antigen receptor macrophage (CAR-M) therapy, holds great promise for immunotherapy, yet is constrained by the challenge of efficient gene delivery into primary macrophages, which are notoriously resistant to transfection. While conventional strategies focus on optimizing the physicochemical properties of lipid nanoparticles (LNP), they often fail to overcome the intrinsic biological barriers of these cells. Here, we introduced a “bioactive nanocarrier” paradigm, hypothesizing that incorporating a cellular modulator directly into LNP structure can synergistically overcome these barriers. We designed and synthesized a novel LNP by integrating the pro-inflammatory fatty acid, arachidonic acid (ARA), as a functional structural component (ARA-LNP). Systematic optimization of the ARA content and mRNA payload revealed a formulation that achieves high transfection efficiency (83.76%) in primary M2-polarized bone marrow-derived macrophages (BMDMs), a cell type that recapitulates pro-tumoral phenotype in the tumor microenvironment. Leveraging this advanced delivery platform, we successfully generated HER2-targeting CAR-M that demonstrated potent and specific phagocytic activity against HER2-expressing tumor cells in vitro. This work presents a powerful strategy where the nanocarrier itself transiently modulates the target cell state to enhance gene delivery, providing a new design principle for engineering macrophages and other hard-to-transfect immune cells for therapeutic applications. Full article

Chronic obstructive pulmonary disease (COPD) involves persistent inflammation and dysregulated lipid metabolism, with foamy macrophages playing a central role in disease progression. Exosomes—vesicles transporting microRNAs (miRNAs)—mediate intercellular communication, but their contribution to foamy macrophage-driven COPD remains unclear. This study investigates the role of exosomal miRNAs, particularly let-7, in modulating lipid metabolism and inflammation in foamy macrophages. Bone marrow-derived macrophages (BMDMs) were treated with oxidized low-density lipoprotein (oxLDL) and lipopolysaccharide (LPS) to induce foamy macrophage formation. Exosomal miRNA profiles were analyzed, and the function of let-7c-3p was assessed via transfection. Foamy macrophages released significantly more exosomes (392.7 × 10⁷ particles) than controls (284.9–302.5 × 10⁷), without differences in exosome size or molecular content. The miRNA sequencing and qRT-PCR confirmed downregulation of exosomal let-7c-3p in foamy macrophages, correlating with increased RNF8 and decreased RXR expression—markers of disrupted PPAR/RXR signaling. Pathway analysis implicated let-7c-3p in regulating PPAR/RXR, WNT/β-catenin, and pulmonary fibrosis pathways. Transfection with let-7 mimics reduced lipid accumulation (52% to 19%), suppressed RNF8, restored RXR, and lowered IL-6 and TNF-α levels, indicating strong anti-inflammatory and lipid-modulating effects. Loss of exosomal let-7c-3p aggravates lipid dysregulation and inflammation in COPD by impairing PPAR/RXR signaling. Restoring let-7 expression reverses these effects, highlighting its potential as a diagnostic biomarker and therapeutic target. Full article

Macrophages are critical to the formation of infection- and non-infection-associated immune structures such as cancer spheroids, pathogen-, and non-pathogen-associated granulomas, contributing to the spatiotemporal and chemical immune response and eventual outcome of disease. While well established in cancer immunology, the prevalence of using three-dimensional (3D) cultures to characterize later-stage structural immune response in pathogen-associated granulomas continues to increase, generating valuable insights for empirical and computational analysis. To enable integration of data from 3D in vitro studies with the vast bibliome of standard two-dimensional (2D) tissue culture data, methods that determine concordance between 2D and 3D immune response need to be established. Focusing on macrophage migration and oxidative species production, we develop experimental and computational methods to enable concurrent spatiotemporal and biochemical characterization of 2D versus 3D macrophage–mycobacterium interaction. We integrate standard biological sampling methods, time-lapse confocal imaging, and 4D quantitative image analysis to develop a 3D ex vivo model of Mycobacterium smegmatis infection using bone-marrow-derived macrophages (BMDMs) embedded in reconstituted basement membrane (RBM). Comparing features of 2D to 3D macrophage response that contribute to control and resolution of bacteria infection, we determined that macrophages in 3D environments increased production of reactive species, motility, and differed in cellular volume. Results demonstrate a viable and extensible approach for comparison of 2D and 3D datasets and concurrent biochemical plus spatiotemporal characterization of initial macrophage structural response during infection. Full article

Crohn’s disease is a chronic, idiopathic inflammatory bowel disease characterized by patchy, transmural inflammation that is influenced by genetic, environmental, and microbial factors. The NOD2 pathway mediates NFκB activation and pro-inflammatory cytokine production. In the SHIP–/– murine model of Crohn’s disease-like ileitis, macrophage-derived IL-1β production drives intestinal inflammation. SHIP reduces NOD2 signaling by preventing downstream interaction between RIPK2 and XIAP, leading us to hypothesize that blocking RIPK2 in SHIP–/– mice would ameliorate intestinal inflammation. We examined the effects of RIPK2 inhibition on pro-inflammatory cytokine production in SHIP+/+ and SHIP–/– macrophages and in mice, using the RIPK2 inhibitor, GSK2983559. We found that GSK2983559 blocked RIPK2 activation in SHIP+/+ and SHIP–/– bone marrow-derived macrophages (BMDMs), and reduced Il1b transcription and IL-1β production in (MDP+LPS)-stimulated SHIP–/– BMDMs. Despite the reduction of IL-1β production in BMDMs, in vivo treatment with GSK2983559 worsened intestinal inflammation and increased IL-1β concentrations in the ileal tissues of SHIP–/– mice. GSK2983559 only modestly reduced IL-1β in (MDP+LPS)-stimulated SHIP–/– peritoneal macrophages, and did not suppress pro-inflammatory cytokine production in response to TLR ligands in peritoneal macrophages from either SHIP+/+ or SHIP–/– mice. Taken together, our data suggest that although RIPK2 inhibition can block IL-1β production by (MDP+LPS)-stimulated macrophages in vitro, it is not an effective anti-inflammatory strategy in vivo, highlighting the limitations of targeting RIPK2 to treat intestinal inflammation in the context of SHIP deficiency. Full article