Primary Murine Macrophages Research Articles

Cell-free hemoglobin triggers macrophage cytokine production via TLR4 and MyD88.

Cell-free hemoglobin (CFH) is elevated in the airspace of patients with acute respiratory distress syndrome (ARDS) and is sufficient to cause acute lung injury in a murine model. However, the pathways through which CFH causes lung injury are not well understood. Toll-like receptor 4 (TLR4) is a mediator of inflammation after detection of damage- and pathogen-associated molecular patterns. We hypothesized that TLR4 signaling mediates the proinflammatory effects of CFH in the airspace. After intratracheal CFH, BALBc mice deficient in TLR4 had reduced inflammatory cell influx into the airspace [bronchoalveolar lavage (BAL) cell counts, median TLR4 knockout (KO): 0.8 × 104/mL [IQR 0.4-1.2 × 104/mL], wild-type (WT): 3.0 × 104/mL [2.2-4.0 × 104/mL], P < 0.001] and attenuated lung permeability (BAL protein, TLR4KO: 289 µg/mL [236-320], WT: 488 µg/mL [422-536], P < 0.001). These mice also had attenuated production of interleukin (IL)-1β, IL-6, and tumor necrosis factor (TNF)-α in the airspace. C57Bl/6 mice lacking TLR4 on myeloid cells only (LysM.Cre+/-TLR4fl/fl) had reduced cytokine production in the airspace after CFH, without attenuation of lung permeability. In vitro studies confirm that WT primary murine alveolar macrophages exposed to CFH (0.01-1 mg/mL) had dose-dependent increases in IL-6, IL-1 β, CXC motif chemokine ligand 1 (CXCL-1), TNF-α, and IL-10 (P < 0.001). Murine MH-S alveolar-like macrophages show TLR4-dependent expression of IL-1β, IL-6, and CXCL-1 in response to CFH. Primary alveolar macrophages from mice lacking TLR4 adaptor proteins myeloid differentiation primary response 88 (MyD88) or TIR-domain-containing adapter-inducing interferon-β (TRIF) revealed that MyD88KO macrophages had 71-96% reduction in CFH-dependent proinflammatory cytokine production (P < 0.001), whereas macrophages from TRIFKO mice had variable changes in cytokine responses. These data demonstrate that myeloid TLR4 signaling through MyD88 is a key regulator of airspace inflammation in response to CFH.NEW & NOTEWORTHY Cell-free hemoglobin (CFH) is elevated in the airspace of most patients with acute respiratory distress syndrome and causes severe inflammation. Here, we identify that CFH contributes to macrophage-induced cytokine production via Toll-like receptor 4 (TLR4) and myeloid differentiation primary response 88 (MyD88) signaling. These data increase our knowledge of the mechanisms through which CFH contributes to lung injury and may inform development of targeted therapeutics to attenuate inflammation.

CXCL10 deficiency limits macrophage infiltration, preserves lung matrix, and enables lung growth in bronchopulmonary dysplasia

Preterm infants with oxygen supplementation are at high risk for bronchopulmonary dysplasia (BPD), a neonatal chronic lung disease. Inflammation with macrophage activation is central to the pathogenesis of BPD. CXCL10, a chemotactic and pro-inflammatory chemokine, is elevated in the lungs of infants evolving BPD and in hyperoxia-based BPD in mice. Here, we tested if CXCL10 deficiency preserves lung growth after neonatal hyperoxia by preventing macrophage activation. To this end, we exposed Cxcl10 knockout (Cxcl10−/−) and wild-type mice to an experimental model of hyperoxia (85% O2)-induced neonatal lung injury and subsequent regeneration. In addition, cultured primary human macrophages and murine macrophages (J744A.1) were treated with CXCL10 and/or CXCR3 antagonist. Our transcriptomic analysis identified CXCL10 as a central hub in the inflammatory network of neonatal mouse lungs after hyperoxia. Quantitative histomorphometric analysis revealed that Cxcl10−/− mice are in part protected from reduced alveolar. These findings were related to the preserved spatial distribution of elastic fibers, reduced collagen deposition, and protection from macrophage recruitment/infiltration to the lungs in Cxcl10−/− mice during acute injury and regeneration. Complimentary, studies with cultured human and murine macrophages showed that hyperoxia induces Cxcl10 expression that in turn triggers M1-like activation and migration of macrophages through CXCR3. Finally, we demonstrated a temporal increase of macrophage-related CXCL10 in the lungs of infants with BPD. In conclusion, our data demonstrate macrophage-derived CXCL10 in experimental and clinical BPD that drives macrophage chemotaxis through CXCR3, causing pro-fibrotic lung remodeling and arrest of alveolarization. Thus, targeting the CXCL10-CXCR3 axis could offer a new therapeutic avenue for BPD.

Cyasterone ameliorates sepsis-related acute lung injury via AKT (Ser473)/GSK3β (Ser9)/Nrf2 pathway

BackgroundAcute lung injury (ALI) is a severe disease that can lead to acute respiratory distress syndrome (ARDS), characterized by intractable hypoxemia, poor lung compliance, and respiratory failure, severely affecting patients' quality of life. The pathogenesis of ALI has not been fully elucidated yet, and sepsis is an important cause of ALI. Among the organ injuries caused by sepsis, the lungs are the earliest damaged ones. Radix cyathulae is reported to have analgesic, anti-inflammatory, and anti-aging effects. Cyasterone is extracted from Radix cyathulae. However, it is not known whether cyasterone has protective effects for ALI. This study aims to investigate the effect of cyasterone on sepsis-related ALI and its mechanism.MethodsWe used the cecal ligation peferation (CLP) method to establish a mouse sepsis model, and cyasterone was given intraperitoneally on days 1–3 to observe its preventive effect on sepsis-related acute lung injury. Primary murine peritoneal macrophages were used to investigate the molecular mechanism of cyasterone in vitro.ResultsCyasterone pretreatment inhibits pro-inflammatory cytokine production, NLRP3 inflammasome activation, and oxidative stress in vivo and in vitro. In addition, cyasterone attenuates sepsis-induced ALI by activating nuclear factor erythroid2-related factor (Nrf2), which may be associated with AKT(Ser473)/GSK3β(Ser9) pathway activation.ConclusionsCyasterone defends against sepsis-induced ALI by inhibiting inflammatory responses and oxidative stress, which depends heavily on the upregulation of the Nrf2 pathway through phosphorylation of AKT(Ser473)/GSK3β(Ser9). These results suggest cyasterone may be a valuable drug candidate for preventing sepsis-related ALI.

CD4+LAG3+T cells are decreased in SSc-ILD and affect fibroblast mesenchymal transition by TGF-β3

Pulmonary fibrosis frequently occurs in rheumatic conditions, particularly systemic sclerosis-associated interstitial lung disease (SSc-ILD). The pathology involves cell transformation into interstitial structures and collagen accumulation. CD4+LAG3+T cells, known for immune inhibition, are relevant in autoimmunity. This study investigates CD4+LAG3+T cells in SSc-ILD. Clinical analysis revealed a correlation between CD4+LAG3+T cells and interleukin-6 (IL-6) and erythrocyte sedimentation rate (ESR). Using primary human lung fibroblasts (pHLFs) and murine bone marrow-derived macrophages (BMDMs), we showed that CD4+LAG3+T cells secreted TGF-β3 inhibits TGF-β1-induced mesenchymal transformation, modulates cellular function, and reduces collagen release. In mouse models, CD4+LAG3+T cells exhibited potential in alleviating bleomycin-induced pulmonary fibrosis. This study emphasizes CD4+LAG3+T cells' therapeutic promise against fibrosis and proposes their role as biomarkers.

Effects of lysine deacetylase inhibitor treatment on LPS responses of alveolar-like macrophages.

Macrophages are key immune cells that can adapt their metabolic phenotype in response to different stimuli. Lysine deacetylases are important enzymes regulating inflammatory gene expression and lysine deacetylase inhibitors have been shown to exert anti-inflammatory effects in models of chronic obstructive pulmonary disease. We hypothesized that these anti-inflammatory effects may be associated with metabolic changes in macrophages. To validate this hypothesis, we used an unbiased and a targeted proteomic approach to investigate metabolic enzymes, as well as liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry, to quantify metabolites in combination with the measurement of functional parameters in primary murine alveolar-like macrophages after lipopolysaccharide-induced activation in the presence or absence of lysine deacetylase inhibition. We found that lysine deacetylase inhibition resulted in reduced production of inflammatory mediators such as tumor necrosis factor α and interleukin 1β. However, only minor changes in macrophage metabolism were observed, as only one of the lysine deacetylase inhibitors slightly increased mitochondrial respiration while no changes in metabolite levels were seen. However, lysine deacetylase inhibition specifically enhanced expression of proteins involved in ubiquitination, which may be a driver of the anti-inflammatory effects of lysine deacetylase inhibitors. Our data illustrate that a multiomics approach provides novel insights into how macrophages interact with cues from their environment. More detailed studies investigating ubiquitination as a potential driver of lysine deacetylase inhibition will help developing novel anti-inflammatory drugs for difficult-to-treat diseases such as chronic obstructive pulmonary disease.

Multi-Faceted Bioactivity Assessment of an Exopolysaccharide from Limosilactobacillus fermentum NCDC400: Antioxidant, Antibacterial, and Immunomodulatory Proficiencies.

Exopolysaccharides (EPS) are acknowledged for their diverse functional and technological properties. This study presents the characterization of EPS400, an acidic exopolysaccharide sourced from the native probiotic Limosilactobacillus fermentum NCDC400. Notably, this strain has demonstrated previous capabilities in enhancing dairy food texture and displaying in vivo hypocholesterolemic activity. Our investigation aimed to unveil EPS400's potential biological roles, encompassing antioxidant, antibacterial, and immunomodulatory activities. The results underscore EPS400's prowess in scavenging radicals, including the 2,2-diphenyl-1-picrylhydrazyl radical, 2,2'-azino-di-(3-ethylbenzthiazoline sulfonic acid) radical, superoxide radical, hydroxyl radical, and chelating activity targeting the ferrous ion. Furthermore, EPS400 displayed substantial antibacterial effectiveness against prevalent food spoilage bacteria such as Pseudomonas aeruginosa NCDC105 and Micrococcus luteus. Remarkably, EPS400 exhibited the ability to modulate cytokine production, downregulating pro-inflammatory cytokines TNF-α, IL-1β, IL-6, and nitric oxide, while concurrently promoting the release of anti-inflammatory cytokine IL-10 within lipopolysaccharide-activated murine primary macrophages. Additionally, EPS400 significantly (p ≤ 0.05) enhanced the phagocytic potential of macrophages. Collectively, our findings spotlight EPS400 as a promising contender endowed with significant antioxidant, antibacterial, and immunomodulatory attributes. These characteristics propose EPS400 as a potential pharmaceutical or bioactive component, with potential applications in the realm of functional food development.

A suspension of inactivated bacteria used for vaccination against recurrent urinary tract infections increases the phagocytic activity of murine macrophages.

Urinary tract infections are a major cause of the consumption of antibiotics in humans. We studied the effect of a vaccine (StroVac®, containing inactivated bacteria and used to prevent recurrent urinary tract infections) licensed in Germany on the release of pro-inflammatory cytokines and the phagocytosis of Escherichia (E.) coli in primary murine macrophages and the macrophage cell line J774A.1. StroVac® increased the release of the cytokines TNF-α, IL-6, IL-12/23 p40, and IL-1β and stimulated the phagocytosis of E. coli in a dose-dependent manner. This effect was independent of LPS as shown by the use of macrophages isolated from LPS-resistant C3H/HeJ mice. At concentrations up to 30 mg/l it was not toxic to bacteria or eukaryotic cells. StroVac® does not only act via the adaptive but also by stimulating the innate immune system. This stimulation may help to build trained innate immunity against bacterial pathogens involved in recurrent urinary tract infections.

Immune regulator IRF1 contributes to ZBP1-, AIM2-, RIPK1-, and NLRP12-PANoptosome activation and inflammatory cell death (PANoptosis)

The innate immune system provides the first line of defense against pathogens and cellular insults and is activated by pattern recognition receptors sensing pathogen- or damage-associated molecular patterns. This activation can result in inflammation via cytokine release as well as the induction of lytic regulated cell death (RCD). Innate immune signaling can also induce the expression of interferon regulatory factor 1 (IRF1), an important molecule in regulating downstream inflammation and cell death. While IRF1 has been shown to modulate some RCD pathways, a comprehensive evaluation of its role in inflammatory cell death pathways is lacking. Here, we examined the role of IRF1 in cell death during inflammasome and PANoptosome activation using live cell imaging, Western blotting, and ELISA in primary murine macrophages. IRF1 contributed to the induction of ZBP1- (Z-DNA binding protein 1), AIM2- (absent in melanoma-2), RIPK1- (receptor interacting protein kinase 1), and NLRP12 (NOD-like receptor family, pyrin domain-containing 12)-PANoptosome activation and PANoptosis. Furthermore, IRF1 regulated the cell death under conditions where inflammasomes, along with caspase-8 and RIPK3, act as integral components of PANoptosomes to drive PANoptosis. However, it was dispensable for other inflammasomes that form independent of the PANoptosome to drive pyroptosis. Overall, these findings define IRF1 as an upstream regulator of PANoptosis and suggest that modulating the activation of molecules in the IRF1 pathway could be used as a strategy to treat inflammatory and infectious diseases associated with aberrant inflammatory cell death.

Termination of STING responses is mediated via ESCRT‐dependent degradation

cGAS‐STING signalling is induced by detection of foreign or mislocalised host double‐stranded (ds)DNA within the cytosol. STING acts as the major signalling hub, where it controls production of type I interferons and inflammatory cytokines. Basally, STING resides on the ER membrane. Following activation STING traffics to the Golgi to initiate downstream signalling and subsequently to endolysosomal compartments for degradation and termination of signalling. While STING is known to be degraded within lysosomes, the mechanisms controlling its delivery remain poorly defined. Here we utilised a proteomics‐based approach to assess phosphorylation changes in primary murine macrophages following STING activation. This identified numerous phosphorylation events in proteins involved in intracellular and vesicular transport. We utilised high‐temporal microscopy to track STING vesicular transport in live macrophages. We subsequently identified that the endosomal complexes required for transport (ESCRT) pathway detects ubiquitinated STING on vesicles, which facilitates the degradation of STING in murine macrophages. Disruption of ESCRT functionality greatly enhanced STING signalling and cytokine production, thus characterising a mechanism controlling effective termination of STING signalling.

Adjuvant effects of peptidoglycan on CD4 +T cell activation by MHC-II +fibroblast-like synoviocytes

Abstract Lyme arthritis (LA) is the predominant late-stage manifestation of Lyme disease, caused by tick-borne spirochete Borrelia burgdorferi. LA can resolve with antibiotic therapy or persist after treatment in a subset of patients, known as post-antibiotic LA. Post-antibiotic LA is characterized by proliferative synovitis, dysregulated Th1/ IFNɣ responses and MHC-II+ fibroblast-like synoviocytes (FLS), a common cell type in inflamed joints. High levels of B. burgdorferi peptidoglycan (PG) have been found in LA patient synovia, yet the effects of PG on host immune responses are not well characterized. We hypothesize that PG acts as an adjuvant to enhance antigen presentation and CD4 +T cell activation in the joint. To test this, primary murine macrophages and FLS, both abundant in LA synovia, were treated in vitro with IFNɣ, PG, or both. Stimulation of macrophages led to upregulation of MHC-II in an IFNɣ-dependent manner, as expected. FLS stimulated with IFNɣ led to upregulation of MHC-II and production of proinflammatory cytokines, which was enhanced by PG as well as the muramyl-dipeptide subunit of PG, a known NOD2 ligand. To examine T cell responses, IFNɣ-primed MHC-II +FLS were co-cultured with OT-II mouse T cells (all with identical antigen-specific T cell receptors) and supplemented with the cognate OVA 323–339peptide. MHC-II +FLS activated naïve CD4 +T cell proliferation, which was enhanced by PG stimulation. Co-culture supernatants showed upregulated IFNɣ and IL-12 production, indicating a Th1 response. Negative controls using an alternative OVA 257–264peptide or NOD2-deficient FLS failed to induce T cell responses. These data show that PG acts as an immune adjuvant enhancing peptide-specific CD4 +T cell activation by MHC-II +FLS.

Syk-Dependent Responses and Innate Cytosolic Defenses in Orientia tsutsugamushi-infected Macrophages

Abstract Orientia tsutsugamushi is an obligately intracellular bacterium and the etiological agent of scrub typhus. Human studies and animal models of scrub typhus have shown robust type 1-skewed proinflammatory responses during severe infection. Macrophages play a critical role in initiating such responses, yet mechanisms of innate recognition for O. tsutsugamushi remain unclear. In this study, we investigated whether Syk-dependent C-type lectin receptors (CLRs) contribute to innate immune recognition and the generation of proinflammatory responses. To validate a role of CLRs in scrub typhus, we infected murine primary macrophages with O. tsutsugamushi in the presence of selective Syk inhibitors and analyzed a panel of CLRs and proinflammatory markers via qRT-PCR. We found that Mincle/Clec4a and Clec5a transcription was significantly abrogated upon Syk inhibition at 6 hours of infection. The effect of Syk inhibition on Mincle protein expression was validated via western blot. Syk-inhibited MF had diminished expression of type 1 cytokines and chemokines (Il12p40, Tnf, Il27p28, Cxcl1) during infection. Additionally, expression of innate immune cytosolic sensors (Mx1 and Oas 1–3) was highly induced in the brain of lethally infected mice. We established that Mx1 and Oas1 expression was reduced in Syk-inhibited MF, while Oas2, Oas3, and MerTK were not sensitive to Syk inhibition. This study reveals that Syk-dependent CLRs contribute to inflammatory responses to O. tsutsugamushi. It also provides the first evidence for Syk-dependent activation of intracellular defenses during infection, suggesting a role of pattern recognition receptor crosstalk in orchestrating macrophage-mediated responses to this poorly studied bacterium. Supported by the NIAID grants (R21 AI156536, R01 AI132674, and T32 AI007526). JF was the recipient of a NIAID Emerging and Tropical Infectious Diseases T32 fellowship.

Hypercapnia alters mitochondrial gene expression and acylcarnitine production in monocytes.

CO2 is produced during aerobic respiration. Normally, levels of CO2 in the blood are tightly regulated but pCO2 can rise (hypercapnia, pCO2 > 45 mmHg) in patients with lung diseases, for example, chronic obstructive pulmonary disease (COPD). Hypercapnia is a risk factor in COPD but may be of benefit in the context of destructive inflammation. The effects of CO2 per se, on transcription, independent of pH change are poorly understood and warrant further investigation. Here we elucidate the influence of hypercapnia on monocytes and macrophages through integration of state-of-the-art RNA-sequencing, metabolic and metabolomic approaches. THP-1 monocytes and interleukin 4-polarized primary murine macrophages were exposed to 5% CO2 versus 10% CO2 for up to 24 h in pH-buffered conditions. In hypercapnia, we identified around 370 differentially expressed genes (DEGs) under basal and about 1889 DEGs under lipopolysaccharide-stimulated conditions in monocytes. Transcripts relating to both mitochondrial and nuclear-encoded gene expression were enhanced in hypercapnia in basal and lipopolysaccharide-stimulated cells. Mitochondrial DNA content was not enhanced, but acylcarnitine species and genes associated with fatty acid metabolism were increased in hypercapnia. Primary macrophages exposed to hypercapnia also increased activation of genes associated with fatty acid metabolism and reduced activation of genes associated with glycolysis. Thus, hypercapnia elicits metabolic shifts in lipid metabolism in monocytes and macrophages under pH-buffered conditions. These data indicate that CO2 is an important modulator of monocyte transcription that can influence immunometabolic signaling in immune cells in hypercapnia. These immunometabolic insights may be of benefit in the treatment of patients experiencing hypercapnia.

Abstract 1350: Kupffer cells secrete CXCL5 to promote liver cancer

Abstract Liver carcinoma is the 6th most prevalent cancer worldwide in 2020. Moreover, it is the 3rd leading cause of cancer related deaths. In addition to the genomic and transcriptomic heterogeneity of liver tumor cells which is recognized as a major driver in liver cancer progression, the liver immune system is also fundamental to liver carcinogenesis and presents a promising target for therapy. The liver immune response is orchestrated by cytokines and chemokines. Recent studies suggest that chemokines not only recruit immune cells but also regulate various liver functions. In partial hepatectomy, CXCL2 has been shown to promote hepatocyte proliferation. CXCL1, 2, 5 and 8 can induce endothelial cells chemotaxis to promote angiogenesis through binding to CXCR2. These diverse functions suggest that chemokines could play multifaceted roles in liver cancer development. However, chemokines that are commonly associated with liver cancer is still unknown.We analyzed HCC patient data from the GEO database, and we categorized the datasets based on HCC etiologies including HBV, HCV, alcoholic and NASH. We identified CXCL5 as the only chemokine consistently upregulated in HCC with different etiologies compared to healthy or cirrhotic livers. Immunohistochemistry (IHC) analysis reveals that CXCL5 was produced by immune cells but not tumor cells in human HCC tissues. To further study HCC associated CXCL5 expression, the liver-specific Pten deletion mouse model (PM mice) that recapitulates NAFLD-NASH-HCC progression was used. A gradual increase of hepatic CXCL5 expression is observed during HCC development, reaching nearly 100-fold upregulation of CXCL5 mRNA expression in 12-month-old PM mice livers carrying tumors. Examination of liver immune cell populations showed that macrophages were significantly enriched in Pten deleted livers bearing tumors than wild type livers without tumors. Flow cytometry and IHC analysis further identified Kupffer cells (KCs), the liver resident macrophages as the source of CXCL5 in tumor bearing livers using these mice. Since increased LPS is a prominent feature in most chronic liver diseases, we isolated and treated mouse KCs with LPS and found that LPS treatment robustly increased CXCL5 expression by nearly 20-fold. Interestingly, neither murine macrophage cell lines nor primary peritoneal macrophages displayed induced CXCL5 expression in response to LPS. These data suggest that induction of CXCL5 in KCs is likely a unique function of the KCs but not of other macrophages. To explore the function of CXCL5 in HCC development, we treated mouse hepatocytes and HCC cells with CXCL5 and showed that CXCL5 induces the proliferation of these cells. This effect is further blocked by the inhibition of CXCR2, the receptor of CXCL5, demonstrating the specificity for CXCL5 mediated effects. Together we show here for the first time that CXCL5 expression is a unique property of Kupffer cells and the induction of CXCL5 promotes HCC progression. Citation Format: Taojian Tu, Handan Hong, Lina He, Mario Alba, Curtis T. Okamoto, Bangyan L. Stiles. Kupffer cells secrete CXCL5 to promote liver cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 1350.

Abstract 576: ACTM-838, a novel immunotherapy that enriches in solid tumors after IV dosing and comprehensively reverses the immunosuppressive TME to promote durable anti-tumor immunity

Abstract ACTM-838 is an avirulent bacterial immunotherapy that encodes an engineered IL-15 (IL-15plex) and a constitutively active STING variant (eSTING). The ACTM-838 strain is a highly modified, attenuated S. Typhimurium that lacks several major inflammatory and immunogenic components on the surface of the microbe and is designed to naturally and specifically enrich in the tumor microenvironment (TME) via auxotrophic dependency on metabolites of the adenosine pathway and purines, to achieve tumor-specific payload delivery. ACTM-838 was selectively internalized by phagocytic, primary human antigen presenting cells (APCs) but not endothelial cells. ACTM-838 was stable in human whole blood and is not inactivated by complement. Human macrophage uptake of labeled ACTM-838 led to acidic lysosomes and nuclear delivery with a concomitant increase in expression of encoded IL-15plex and eSTING payloads such as IL-15, IRF3 reporter activity and IFN ⍺/β secretion, respectively. Primary human and murine macrophages polarized towards a dual co-stimulatory and phagocytic M1/M2 dual phenotype in response to ACTM-838. ACTM-838 delivered eSTING payload in STING knockout macrophages and induced significantly higher Type I IFN production over a negative control strain. IV delivered ACTM-838 showed dose and payload dependent tumor enrichment and potent single-agent efficacy in two independent syngeneic tumor models, EMT6 (orthotopic) and MC38. Sustained memory anti-tumor immunity upon tumor rechallenge in cured animals was demonstrated. ACTM-838 treated tumors exhibited a significant increase in human IL-15plex protein payload. ACTM-838 as a single agent induced profound immune reprogramming and remodeling of the TME over time through increased infiltration and activation of myeloid, NK, B and cytolytic CD8 T cells, MHC class I and II, antigen presentation as well as decreased Treg, PD1+Lag3+ exhausted T cells, and a remodeled stromal signature, as assessed by bulk RNAseq, and confirmed by flow cytometry. Synergistic anti-tumor activity was observed in multiple tumor models when ACTM-838 was dosed in combination with anti-PD1, safely inducing complete responses. No significant body weight loss or death was observed in any treatment regimens of ACTM-838 alone (single or multiple doses) or in combination with anti-PD1. Analyses of public RNAseq datasets from patients with primary or metastatic disease revealed cancer types with high levels of myeloid infiltration and adenosine enrichment, suggesting that ACTM-838 efficacy could provide benefit in these indications. ACTM-838 is a novel immunotherapy delivering IL-15plex + eSTING payloads to phagocytic APCs, inducing a durable anti-tumor immune response, after IV dosing. It possesses a compelling safety profile, and is currently in IND-enabling, preclinical development. Citation Format: Ping Fang, Kyle R. Cron, Oanh Pham, Julie R. Janes, John Brandenburg, Fauna Yarza, Bret Peterson, Christopher Thanos, Chan Whiting, Akshata R. Udyavar. ACTM-838, a novel immunotherapy that enriches in solid tumors after IV dosing and comprehensively reverses the immunosuppressive TME to promote durable anti-tumor immunity [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 576.

HuR modulation with tanshinone mimics impairs LPS response in murine macrophages.

Lipopolysaccharide exposure to macrophages induces an inflammatory response that is heavily regulated at the transcriptional and post-transcriptional levels. HuR (ELAVL1) is an RNA binding protein that binds and regulates the maturation and half-life of AU/U rich elements (ARE) containing cytokines and chemokines transcripts, mediating the LPS-induced response. Here we investigated how and to what extent small molecule tanshinone mimics (TMs) inhibiting HuR-RNA interaction counteract LPS stimulus in macrophages. We show TMs exist in solution in keto-enolic tautomerism and that, by molecular dynamic calculations, the orto quinone form is the bioactive species interacting with HuR and inhibiting its binding mode vs mRNA targets. A chemical blockage of the diphenolic, reduced form as a diacetate caused the loss of activity of TMs in vitro but resulted to prodrug-like activity in vivo. The murine macrophage cell line RAW264.7 was treated with LPS and TMs, and the modulation of cellular LPS-induced response was monitored by RNA and Ribonucleoprotein immunoprecipitation sequencing. Correlation analyses indicated that LPS induced a strong coupling between differentially expressed genes and HuR-bound genes, and that TMs reduced such interactions. Functional annotation addressed a specific set of genes involved in chemotaxis and immune response, such as Cxcl10, Il1b, Cd40, and Fas, with a decreased association with HuR, a reduction of their expression and protein secretion. The same effect was observed in primary murine bone marrow-derived macrophages, and in vivo in an LPS induced peritonitis model, in which the serum level of Cxcl10 and Il1b was strongly reduced, endowing TMs such as TM7nox with remarkable anti-inflammatory properties in vivo.

RAW 264.7 Macrophage Cell Line: In Vitro Model for the Evaluation of the Immunomodulatory Activity of Zingiberaceae

The immune response plays an essential role in the body's defense against infection. Macrophages are promising targets against which to screen agents that modulate immune responses. In vitro analysis, primarily using cell lines, is preferred to screen bioactivity initially. RAW 264.7 cells comprise a model macrophage cell line close to primary murine macrophages. Indonesian people often use the Zingiberaceae family or “empon-empon" in the favorable treatment of several diseases, including immune disorders. This review highlights several studies of Zingiberaceae using RAW 264.7 cells, focusing on the observed immunomodulatory activity and assay methods. The research on RAW 264.7 macrophage cell line in Zingiberaceae was gathered using Scopus, PubMed, ScienceDirect, and Google Scholar from 2012-2021. Based on the reviews, the Zingiberaceae family has immunomodulatory effects by increasing or decreasing inflammatory mediators such as NO, IL-6, TNF-α, IL-1β, IL-10, and phagocytosis activity in RAW 264.7 cells. Several methods can assess the activation of RAW 264.7 cells, including cell viability assays using 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT); measuring nitric oxide production (Griess reaction), cytokine production (enzyme-linked immunosorbent assay [ELISA]), and phagocytosis (neutral red uptake assay); and detecting DNA (real-time quantitative polymerase chain reaction [qPCR]). The information provided in this review presents avenues for future investigations of the immunomodulatory activity of Zingiberaceae.

Evaluation of the Anti-Inflammatory Properties of Mastic Oil Extracted from Pistacia lentiscus var. chia

Mastic oil (MO) is extracted from the resin of the bark of Pistacia lentiscus var. chia, a tree abundantly grown in the Greek island of Chios. Various biological activities, such as antimicrobial, anticancer and antioxidant, have been associated with the dietary intake of MO. However, little is known about MO’s potential anti-inflammatory effects, while some of its main chemical constituents were reported to exert significant anti-inflammatory activity. This study aims to assay the bioactivity of MO on in vitro and in vivo experimental inflammation models, in particular on LPS-stimulated RAW264.7 macrophages, murine primary peritoneal macrophages and a model of zymosan-induced peritonitis in BALB/c mice. The per os administration of MO inhibited the recruitment of macrophages into the peritoneal cavity of zymosan-treated mice, but did not affect neutrophil mobilisation or the levels of IL-6 or TNF-α in the peritoneal fluid. Similarly, IL-6 and TNF-α secretion in primary LPS-stimulated macrophages was not affected by MO, but the levels of phosphoproteins that activate inflammation in macrophages were differentially regulated. Finally, MO and some of its individual constituents reduced nitric oxide (NO), prostaglandin E2 and TNF-α levels in supernatants of LPS-stimulated RAW264.7 cells and inhibited their phagocytosis rate. Our data imply that MO may promote an anti-inflammatory transition in macrophages due to the combined bioactivities of its individual constituents. Thus, as a mixture of various compounds, MO seems to affect multiple molecular mechanisms that are involved in the development of inflammation. Therefore, more research, focusing on MO’s individual constituents and employing various pre-clinical inflammation models that activate different mechanisms, is required for a detailed investigation of the oil’s potential anti-inflammatory activity.

Influence of PEG Chain Length of Functionalized Magnetic Nanoparticles on the Cytocompatibility and Immune Competence of Primary Murine Macrophages and Dendritic Cells.

A major drawback of nanoparticles (NPs) for biomedical applications is their preferential phagocytosis in immune cells, which can be avoided by surface modifications like PEGylation. Nevertheless, examinations of different polyethylene glycol (PEG) chain lengths on the competence of immune cells as well as possible immunotoxic effects are still sparse. Therefore, primary murine macrophages and dendritic cells were generated and incubated with magnetic nanoporous silica nanoparticles (MNPSNPs) modified with different mPEG chains (2 kDa, 5 kDa, and 10 kDa). Cytotoxicity, cytokine release, and the formation of reactive oxygen species (ROS) were determined. Immune competence of both cell types was examined and uptake of MNPSNPs into macrophages was visualized. Concentrations up to 150 µg/mL MNPSNPs showed no effects on the metabolic activity or immune competence of both cell types. However, ROS significantly increased in macrophages incubated with larger PEG chains, while the concentration of cytokines (TNF-α and IL-6) did not indicate a proinflammatory process. Investigations on the uptake of MNPSNPs revealed no differences in the onset of internalization and the intensity of intracellular fluorescence. The study gives no indication for an immunotoxic effect of PEGylated MNPSNPs. Nevertheless, there is still a need for optimization regarding their internalization to ensure an efficient drug delivery.

Amino Derivatives of Diaryl Pyrimidines and Azolopyrimidines as Protective Agents against LPS-Induced Acute Lung Injury.

The problem of lung damage originating from excessive inflammation and cytokine release during various types of infections remains relevant and stimulates the search for highly effective and safe drugs. The biological activity of the latter may be associated with the regulation of hyperactivation of certain immune cells and enzymes. Here, we propose the design and synthesis of amino derivatives of 4,6- and 5,7-diaryl substituted pyrimidines and [1,2,4]triazolo[1,5-a]pyrimidines as promising double-acting pharmacophores inhibiting IL-6 and NO. The anti-inflammatory activity of 14 target compounds was studied on isolated primary murine macrophages after LPS stimulation. Seven compounds were identified to inhibit the synthesis of nitric oxide and interleukin 6 at a concentration of 100 µM. The most active compounds are micromolar inhibitors of IL-6 secretion and NO synthesis, showing a minimal impact on innate immunity, unlike the reference drug dexamethasone, along with acceptable cytotoxicity. Evaluation in an animal model of acute lung injury proved the protective activity of compound 6e, which was supported by biochemical, cytological and morphological markers.

Live Imaging of Pyroptosis in Primary Murine Macrophages.

Inflammasomes are the ultimate weapon of the macrophage immune arsenal. Inflammasome signalling in macrophages triggers pyroptosis, a lytic cell death pathway that facilitates inflammation-driven pathogen clearance. Imaging-based approaches to investigating cell death have proven useful, revealing cellular remodelling events such as the generation of extracellular vesicles, and continuing to uncover important structural changes in cells involved in inflammatory signalling. Pyroptosis has proved extremely challenging to image, because its lytic nature is incompatible with many well-established imaging approaches employed for other, non-lytic pathways. The complexities of ectopically expressing fluorescent constructs in primary macrophages and the sensitivity of such proteins to drug-based probes compound this difficulty. We and others have demonstrated key differences in pyroptosis induced by canonical versus noncanonical inflammasomes that delineate functional differences between these signalling pathways. Here, we describe a live imaging approach to study and compare canonical versus noncanonical inflammasome signalling and pyroptotic architecture in primary murine macrophages.