TNF-α Secretion In Macrophages Research Articles

Serum amyloid A proteins reduce bone mass during mycobacterial infections.

Osteopenia has been associated to several inflammatory conditions, including mycobacterial infections. How mycobacteria cause bone loss remains elusive, but direct bone infection may not be required. Genetically engineered mice and morphometric, transcriptomic, and functional analyses were used. Additionally, inflammatory mediators and bone turnover markers were measured in the serum of healthy controls, individuals with latent tuberculosis and patients with active tuberculosis. We found that infection with Mycobacterium avium impacts bone turnover by decreasing bone formation and increasing bone resorption, in an IFNγ- and TNFα-dependent manner. IFNγ produced during infection enhanced macrophage TNFα secretion, which in turn increased the production of serum amyloid A (SAA) 3. Saa3 expression was upregulated in the bone of both M. avium- and M. tuberculosis-infected mice and SAA1 and 2 proteins (that share a high homology with murine SAA3 protein) were increased in the serum of patients with active tuberculosis. Furthermore, the increased SAA levels seen in active tuberculosis patients correlated with altered serum bone turnover markers. Additionally, human SAA proteins impaired bone matrix deposition and increased osteoclastogenesis in vitro. Overall, we report a novel crosstalk between the cytokine-SAA network operating in macrophages and bone homeostasis. These findings contribute to a better understanding of the mechanisms of bone loss during infection and open the way to pharmacological intervention. Additionally, our data and disclose SAA proteins as potential biomarkers of bone loss during infection by mycobacteria.

The Role of the Innate Immune System in Wear Debris-Induced Inflammatory Peri-Implant Osteolysis in Total Joint Arthroplasty.

Periprosthetic osteolysis remains a leading complication of total hip and knee arthroplasty, often resulting in aseptic loosening of the implant and necessitating revision surgery. Wear-induced particulate debris is the main cause initiating this destructive process. The purpose of this article is to review recent advances in understanding of how wear debris causes osteolysis, and emergent strategies for the avoidance and treatment of this disease. A strong activator of the peri-implant innate immune this debris-induced inflammatory cascade is dictated by macrophage secretion of TNF-α, IL-1, IL-6, and IL-8, and PGE2, leading to peri-implant bone resorption through activation of osteoclasts and inhibition of osteoblasts through several mechanisms, including the RANK/RANKL/OPG pathway. Therapeutic agents against proinflammatory mediators, such as those targeting tumor necrosis factor (TNF), osteoclasts, and sclerostin, have shown promise in reducing peri-implant osteolysis in vitro and in vivo; however, radiographic changes and clinical diagnosis often lag considerably behind the initiation of osteolysis, making timely treatment difficult. Considerable efforts are underway to develop such diagnostic tools, therapies, and identify novel targets for therapeutic intervention.

Increased angiopoietin-like 4 expression ameliorates inflammatory bowel diseases via suppressing CD8+ T cell activities

Angiopoietin-like 4 (ANGPTL4) is involved in inflammation-associated diseases, such as rheumatoid arthritis, type 2 diabetes, atherosclerosis, and chronic obstructive pulmonary disease. The role of ANGPTL4 in the pathogenesis of inflammatory bowel disease (IBD) remains unknown. Here, the plasma ANGPTL4 levels peaked on days 3 and 5, and expression of ANGPTL4 of inflamed colons peaked on days 5 and 7 in mice with dextran sulfate sodium (DSS)-induced colitis. Simultaneously, CD8+T cells in the inflamed colons peaked at day 5 but declined at day 7. However, the ANGPTL4−/− mice treated with DSS exhibited exacerbated colitis with more CD8+T cells and macrophages infiltrating the colons. The exogenous ANGPTL4 protein protected the mice against DSS-induced colitis with less CD8+T cell and macrophage recruitment in the colons. In addition, recombinant ANGPTL4 directly downregulated the IFN-γ and NKG2D expression of CD8+T cells but had no effects on the CD86 expression and TNF-α secretion of macrophages ex vivo. Adding ANGPTL4 protein into ANGPTL4−/− mice almost blocked the onset of DSS-induced colitis. In parallel, the plasma ANGPTL4 levels were elevated in patients with Crohn's disease and ulcerative colitis at mild/moderate stage and restored to normal levels in IBD patients at a severe stage. The higher ANGPTL4 expression in the inflamed colons of patients with IBD was correlated with lower CD8+ cell infiltration, whereas no associations with macrophages. Our results demonstrated the compensatory protective effect of ANGPTL4 on IBD development at least via the downregulation of CD8+T cell activities. Adding the ANGPTL4 protein would have beneficial effects to retard the progression of IBD.

Brain-Derived Neurotrophic Factor Suppressed Proinflammatory Cytokines Secretion and Enhanced MicroRNA(miR)-3168 Expression in Macrophages

We investigated the role of brain-derived neurotrophic factor (BDNF) and its signaling pathway in the proinflammatory cytokines production of macrophages. The effects of different concentrations of BDNF on proinflammatory cytokines expression and secretion in U937 cell-differentiated macrophages, and human monocyte-derived macrophages were analyzed using enzyme-linked immunosorbent assay and real-time polymerase chain reaction. The CRISPR-Cas9 system was used to knockout p75 neurotrophin receptor (p75NTR), one of the BDNF receptors. Next-generation sequencing (NGS) was conducted to search for BDNF-regulated microRNA. A very low concentration of BDNF (1 ng/mL) could suppress the secretion of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and IL-6 in lipopolysaccharide (LPS)-stimulated macrophages but did not change their mRNA expression. BDNF suppressed IL-1β and IL-6 secretion in human monocyte-derived macrophages. In U937 cells, BDNF suppressed the phosphorylation of JNK and c-Jun. The p75NTR knockout strongly suppressed IL-1β, IL-6, and TNF-α secretion in macrophages and LPS-stimulated macrophages. BDNF regulated the expression of miR-3168 with Ras-related protein Rab-11A as its target. In conclusion, BDNF suppressed proinflammatory cytokines secretion in macrophages and inhibited the phosphorylation of JNK. Knockout of p75NTR suppressed proinflammatory cytokines expression and secretion. BDNF upregulated the expression of miR-3168. The inhibition of p75NTR could be a potential strategy to control inflammation.

Anti-Inflammatory Properties, Bioaccessibility and Intestinal Absorption of Sea Fennel (Crithmum maritimum) Extract Encapsulated in Soy Phosphatidylcholine Liposomes.

A sea fennel (Crithmum maritimum) aqueous extract was prepared and loaded into soybean phosphatidylcholine liposomes. Both the free extract (FE), and the empty (L) and loaded (L-FE) liposomes were shown to be non-cytotoxic to THP-1 and Caco-2 cells. The anti-inflammatory effect was tested on THP-1 cells differentiated into macrophages. FE showed anti-inflammatory activity, revealed by the induced secretion of IL-10 cytokines in macrophages that were subsequently stimulated with LPS. Also, a decrease in TNF-α production by L was observed, evidencing that liposomes reduced the pro-inflammatory mediators’ secretion. The liposomes (L) showed protective anti-inflammatory activity and also were able to downregulate the inflammation. Furthermore, L-FE were also found to downregulate the inflammation response, as they were able to decrease TNF-α secretion in macrophages previously exposed to LPS. The simulated in vitro gastrointestinal digestion (GID) of FE diminished the chlorogenic acid content (the main polyphenolic compound of the extract) by 40%, while in L-FE, the amount of this phenolic compound increased with respect to the undigested liposomes. The amount of bioaccessible chlorogenic, however, was similar for FE and L-FE. The percentage of chlorogenic acid absorbed through a Caco-2 cell monolayer after 3 h of incubation, was significantly similar for the extract and the liposomes (~1.5%), without finding significant differences once the extract and liposomes were digested.

Single-cell RNA-seq of out-of-thaw mesenchymal stromal cells shows tissue-of-origin differences and inter-donor cell-cycle variations

BackgroundHuman Mesenchymal stromal cells (hMSCs) from various tissue sources are widely investigated in clinical trials. These MSCs are often administered to patients immediately after thawing the cryopreserved product (out-of-thaw), yet little is known about the single-cell transcriptomic landscape and tissue-specific differences of out-of-thaw human MSCs.Methods13 hMSC samples derived from 10 “healthy” donors were used to assess donor variability and tissue-of-origin differences in single-cell gene expression profiles. hMSCs derived and expanded from the bone marrow (BM) or cord tissue (CT) underwent controlled-rate freezing for 24 h. Cells were then transferred to the vapor phase of liquid nitrogen for cryopreservation. hMSCs cryopreserved for at least one week, were characterized immediately after thawing using a droplet-based single-cell RNA sequencing method. Data analysis was performed with SC3 and SEURAT pipelines followed by gene ontology analysis.ResultsscRNA-seq analysis of the hMSCs revealed two major clusters of donor profiles, which differ in immune-signaling, cell surface properties, abundance of cell-cycle related transcripts, and metabolic pathways of interest. Within-sample transcriptomic heterogeneity is low. We identified numerous differentially expressed genes (DEGs) that are associated with various cellular functions, such as cytokine signaling, cell proliferation, cell adhesion, cholesterol/steroid biosynthesis, and regulation of apoptosis. Gene-set enrichment analyses indicated different functional pathways in BM vs. CT hMSCs. In addition, MSC-batches showed significant variations in cell cycle status, suggesting different proliferative vs. immunomodulatory potential. Several potential transcript-markers for tissue source differences were identified for further investigation in future studies. In functional assays, both BM and CT MSCs suppressed macrophage TNFα secretion upon interferon stimulation. However, differences between donors, tissue-of-origin, and cell cycle are evident in both TNF suppression and cytokine secretion.ConclusionsThis study shows that donor differences in hMSC transcriptome are minor relative to the intrinsic differences in tissue-of-origin. hMSCs with different transcriptomic profiles showed potential differences in functional characteristics. These findings contribute to our understanding of tissue origin-based differences in out-of-thaw therapeutic hMSC products and assist in the identification of cells with immune-regulatory or survival potential from a heterogeneous MSC population. Our results form the basis of future studies in correlating single-cell transcriptomic markers with immunomodulatory functions.

Antimicrobial Peptide against Mycobacterium Tuberculosis That Activates Autophagy Is an Effective Treatment for Tuberculosis.

Mycobacterium tuberculosis (MTB) is the principal cause of human tuberculosis (TB), which is a serious health problem worldwide. The development of innovative therapeutic modalities to treat TB is mainly due to the emergence of multi drug resistant (MDR) TB. Autophagy is a cell-host defense process. Previous studies have reported that autophagy-activating agents eliminate intracellular MDR MTB. Thus, combining a direct antibiotic activity against circulating bacteria with autophagy activation to eliminate bacteria residing inside cells could treat MDR TB. We show that the synthetic peptide, IP-1 (KFLNRFWHWLQLKPGQPMY), induced autophagy in HEK293T cells and macrophages at a low dose (10 μM), while increasing the dose (50 μM) induced cell death; IP-1 induced the secretion of TNFα in macrophages and killed Mtb at a dose where macrophages are not killed by IP-1. Moreover, IP-1 showed significant therapeutic activity in a mice model of progressive pulmonary TB. In terms of the mechanism of action, IP-1 sequesters ATP in vitro and inside living cells. Thus, IP-1 is the first antimicrobial peptide that eliminates MDR MTB infection by combining four activities: reducing ATP levels, bactericidal activity, autophagy activation, and TNFα secretion.

S100A8/A9 promotes MMP-9 expression in the fibroblasts from cardiac rupture after myocardial infarction by inducing macrophages secreting TNFα.

Inflammation and extracellular matrix degradation play a role in cardiac rupture (CR) after myocardial infarction (MI). It has been found that the expression of inflammatory cytokine S100A8/A9 was elevated in acute MI patients, whereas its impact in CR after infarction remains unclear. Samples from cardiac tissue and peripheral blood of patients with CR after MI, MI, patients without CR, and healthy control (cardiotrauma) were collected to test the expressions of S100A8/A9, p-p65, and MMP-9. Co-culture system for HCF cells and macrophages were established to identify the impact of hypoxia-ischemia on the expressions of S100A8/A9 and TNFα. S100A9 and/or TNFα blocking agent were applied to examine the effect on macrophages migration, expressions of S100A8, S100A9, and TNFα. Western blot was adopted to determine levels of p-p65 and MMP-9 protein after the inhibition of S100A9 and/or TNFα. Compared with healthy control and non-CR patients, serum S100A8/A9 and MMP-9 levels were elevated in cardiac tissues of CR patients, while S100A8/A9, p-p65, and MMP-9 were also overexpressed. Hypoxia-ischemia significantly caused the increasing levels of S100A8/A9 and TNFα in macrophages (p < 0.05). The blockade of S100A9 and/or TNFα suppressed the activation and migration of macrophages. The inhibition of S100A9 expression also decreased the secretion of TNFα in macrophages, while the suppression of TNFα showed no significant impact on S100A8 and S100A9 levels. Downregulation of TNFα or NF-κB markedly declined p-p65 and MMP-9 protein levels in HCF cells from co-culture system or single culture, whereas the blockade of S100A9 only reduced their expressions in co-cultured HCF cells. The level of S100A8/A9 was upregulated in MI patients with CR. S100A8/A9 induced the activation of NF-κB and expression of MMP-9 protein in HCF cells through facilitating secretion of TNFα from macrophages, which may play a role in triggering extracellular matrix degradation and CR.

Donor variability among anti-inflammatory pre-activated mesenchymal stromal cells.

Therapeutic mesenchymal stromal cells (MSCs) are attractive in part due to their immunomodulatory properties, achieved by their paracrine secretion of factors including prostaglandin E2 (PGE2). Despite promising pre-clinical data, demonstrating clinical efficacy has proven difficult. The current studies were designed to develop approaches to pre-induce desired functions from naïve MSCs and examine MSC donor variability, two factors contributing to this disconnect. MSCs from six human donors were pre-activated with interleukin 1 beta (IL-1β) at a concentration and duration identified as optimal or interferon gamma (IFN-γ) as a comparator. Their secretion of PGE2 after pre-activation and secondary exposure to pro-inflammatory molecules was measured. Modulation of tumor necrosis factor alpha (TNF-α) secretion from M1 pro-inflammatory macrophages by co-cultured pre-activated MSCs was also measured. Our results indicated that pre-activation of MSCs with IL-1β resulted in upregulated PGE2 secretion post exposure. Pre-activation with IL-1β or IFN-γ resulted in higher sensitivity to induction by secondary stimuli compared to no pre-activation. While IL-1β pre-activation led to enhanced MSC-mediated attenuation of macrophage TNF-α secretion, IFN-γ pre-activation resulted in enhanced TNF-α secretion. Donor variability was noted in PGE2 secretion and upregulation and the level of improved or impaired macrophage modulation.

The effect of local anesthetic on pro-inflammatory macrophage modulation by mesenchymal stromal cells

Administering local anesthetics (LAs) peri- and post-operatively aims to prevent or mitigate pain in surgical procedures and after tissue injury in cases of osteoarthritis (OA) and other degenerative diseases. Innovative tissue protective and reparative therapeutic interventions such as mesenchymal stromal cells (MSCs) are likely to be exposed to co-administered drugs such as LAs. Therefore, it is important to determine how this exposure affects the therapeutic functions of MSCs and other cells in their target microenvironment. In these studies, we measured the effect of LAs, lidocaine and bupivacaine, on macrophage viability and pro-inflammatory secretion. We also examined their effect on modulation of the macrophage pro-inflammatory phenotype in an in vitro co-culture system with MSCs, by quantifying macrophage tumor necrosis factor (TNF)-α secretion and MSC prostaglandin E2 (PGE2) production. Our studies indicate that both LAs directly attenuated macrophage TNF-α secretion, without significantly affecting viability, in a concentration- and potency-dependent manner. LA-mediated attenuation of macrophage TNF-α was sustained in co-culture with MSCs, but MSCs did not further enhance this anti-inflammatory effect. Concentration- and potency-dependent reductions in macrophage TNF-α were concurrent with decreased PGE2 levels in the co-cultures further indicating MSC-independent macrophage attenuation. MSC functional recovery from LA exposure was assessed by pre-treating MSCs with LAs prior to co-culture with macrophages. Both MSC attenuation of TNF-α and PGE2 secretion were impaired by pre-exposure to the more potent bupivacaine and high dose of lidocaine in a concentration-dependent manner. Therefore, LAs can affect anti-inflammatory function by both directly attenuating macrophage inflammation and MSC secretion and possibly by altering the local microenvironment which can secondarily reduce MSC function. Furthermore, the LA effect on MSC function may persist even after LA removal.

Garlic (Allium sativum) stimulates lipopolysaccharide-induced tumor necrosis factor-alpha production from J774A.1 murine macrophages.

Garlic (Allium sativum) is known to have many beneficial attributes such as antimicrobial, antiatherosclerotic, antitumorigenetic, and immunomodulatory properties. In the present study, we investigated the effects of an aqueous garlic extract on macrophage cytokine production by challenging the macrophage J774A.1 cell line with the garlic extract in the absence or presence of lipopolysaccharide (LPS) under different conditions. The effect of allicin, the major component of crushed garlic, was also investigated. Using enzyme-linked immunosorbent assay and reverse transcriptase-quantitative polymerase chain reaction, it was found that garlic and synthetic allicin greatly stimulated tumor necrosis factor-alpha (TNF-α) production in macrophages treated with LPS. The TNF-α secretion levels peaked earlier and were sustained for a longer time in cells treated with garlic and LPS compared with cells treated with LPS alone. Garlic acted in a time-dependent manner. We suggest that garlic, at least partially via its allicin component, acts downstream from LPS to stimulate macrophage TNF-α secretion.

Integrin-linked Kinase Modulates Lipopolysaccharide- and Helicobacter pylori-induced Nuclear Factor κB-activated Tumor Necrosis Factor-α Production via Regulation of p65 Serine 536 Phosphorylation

Integrin-linked kinase (ILK) is a ubiquitously expressed and highly conserved serine-threonine protein kinase that regulates cellular responses to a wide variety of extracellular stimuli. ILK is involved in cell-matrix interactions, cytoskeletal organization, and cell signaling. ILK signaling has also been implicated in oncogenesis and progression of cancers. However, its role in the innate immune system remains unknown. Here, we show that ILK mediates pro-inflammatory signaling in response to lipopolysaccharide (LPS). Pharmacological or genetic inhibition of ILK in mouse embryonic fibroblasts and macrophages selectively blocks LPS-induced production of the pro-inflammatory cytokine tumor necrosis factor α (TNF-α). ILK is required for LPS-induced activation of nuclear factor κB (NF-κB) and transcriptional induction of TNF-α. The modulation of LPS-induced TNF-α synthesis by ILK does not involve the classical NF-κB pathway, because IκB-α degradation and p65 nuclear translocation are both unaffected by ILK inhibition. Instead, ILK is involved in an alternative activation of NF-κB signaling by modulating the phosphorylation of p65 at Ser-536. Furthermore, ILK-mediated alternative NF-κB activation through p65 Ser-536 phosphorylation also occurs during Helicobacter pylori infection in macrophages and gastric cancer cells. Moreover, ILK is required for H. pylori-induced TNF-α secretion in macrophages. Although ILK-mediated phosphorylation of p65 at Ser-536 is independent of the phosphatidylinositol 3-kinase (PI3K)/Akt pathway during LPS stimulation, upon H. pylori infection this event is dependent on the PI3K/Akt pathway. Our findings implicate ILK as a critical regulatory molecule for the NF-κB-mediated pro-inflammatory signaling pathway, which is essential for innate immune responses against pathogenic microorganisms.

An α-glucan isolated from root of Isatis Indigotica, its structure and adjuvant activity.

The root of Isatis indigotica is a traditional Chinese herbal medicine. An α-glucan (IIP-A-1) was firstly isolated from the roots. In this study we elucidated the chemical structure of IIP-A-1 and determined its adjuvant activity by co-immunizing mice with H1N1 influenza virus split and recombinant hepatitis B surface antigen (HBsAg), respectively. The polysaccharide was pretreated with periodate oxidation, Smith degradation and methylation in order to analyze its structure using GC, HPGPC, FT-IR, NMR and GC-MS. The adjuvant effect was evaluated by determining the antibody titers of serum against H1N1 influenza and HBsAg using ELISA. The proliferation and TNF-α secretion of macrophages administrated with different dose of IIP-A-1 were measured in vitro. The results of this study revealed that IIP-A-1 was an α-glucan with the molecular weight of 3,600 Da. The backbone was α-(1 → 4)-D-glucan with (1 → 6) branch chain. The α-glucan could significantly enhance the immune response of mice immunized with H1N1 influenza or HBsAg in vivo and exert good dose-dependent effects on the proliferation and the TNF-α secretion of macrophages in vitro. These results supported that IIP-A-1 was expected to be an efficacious adjuvant candidate for prophylactic and therapeutic vaccines.

Anti-inflammatory properties of a novel peptide interleukin 1 receptor antagonist

BackgroundInterleukin 1 (IL-1) is implicated in neuroinflammation, an essential component of neurodegeneration. We evaluated the potential anti-inflammatory effect of a novel peptide antagonist of IL-1 signaling, Ilantide.MethodsWe investigated the binding of Ilantide to IL-1 receptor type I (IL-1RI) using surface plasmon resonance, the inhibition of Il-1β-induced activation of nuclear factor κB (NF-κB) in HEK-Blue cells that contained an IL-1β-sensitive reporter, the secretion of TNF-α in macrophages, protection against IL-1-induced apoptosis in neonatal pancreatic islets, and the penetration of Ilantide through the blood–brain barrier using competitive enzyme-linked immunosorbent assay (ELISA). We studied the effects of the peptide on social behavior and memory in rat models of lipopolysaccharide (LPS)- and amyloid-induced neuroinflammation, respectively, and its effect in a rat model of experimental autoimmune enchephalomyelitis.ResultsIlantide bound IL-1RI, inhibited the IL-1β-induced activation of NF-κB, and inhibited the secretion of TNF-α in vitro. Ilantide protected pancreatic islets from apoptosis in vitro and reduced inflammation in an animal model of arthritis. The peptide penetrated the blood–brain barrier. It reduced the deficits in social activity and memory in LPS- and amyloid-treated animals and delayed the development of experimental autoimmune enchephalomyelitis.ConclusionsThese findings indicate that Ilantide is a novel and potent IL-1RI antagonist that is able to reduce inflammatory damage in the central nervous system and pancreatic islets.

The anti-inflammatory effect of a pomegranate husk extract on inflamed adipocytes and macrophages cultivated independently, but not on the inflammatory vicious cycle between adipocytes and macrophages

Obese adipose tissues contain a higher proportion of inflamed macrophages than the normal adipose tissue. Adipocytes and macrophages are known to secrete pro-inflammatory markers that establish the systemic inflammation leading to metabolic complications. CCL-2 secreted by hypertrophied adipocytes attracts and activates macrophages in the adipose tissue. These cells, in turn, secrete TNFα and other pro-inflammatory molecules. The pomegranate husk extract and its phenolic constituents, punicalagin and ellagic acid, have exhibited an anti-inflammatory effect. In this study, we used an in vitro coculture system of 3T3-L1 murine adipocytes and RAW 264.7 macrophages to investigate the potential anti-inflammatory effects of these compounds on the vicious cycle between both cell types. The pomegranate husk extract presented an anti-inflammatory effect on the inflamed cells cultivated independently, as suggested by a decrease of (i) CCL-2 secretion by both cell types, (ii) adipocyte IL-6 expression and secretion, and (iii) macrophage TNFα secretion. Nevertheless and surprisingly, no anti-inflammatory effect was observed in coculture. Punicalagin, at the same concentration as that found in the pomegranate extract, had a more potent effect than the extract and in coculture; it reduced significantly the IL-6 secretion. Ellagic acid decreased TNFα and CCL-2 macrophage secretion, CCL-2 adipocyte secretion and, in coculture, it reduced IL-6 secretion and expression by adipocytes. These results indicate that the pomegranate husk extract has an anti-inflammatory action on adipocytes and macrophages but seems to be not able to reduce the inflammatory vicious cycle between both cells. Ellagitannin and punicalagin showed a better effect on inflammation suggesting that PHE will be a good candidate for more investigations.

Carbon monoxide–based therapy ameliorates acute pancreatitis via TLR4 inhibition

The protective role of hemeoxygenase-1 (HO-1) in various inflammatory conditions is mediated in part by its products, carbon monoxide (CO) and biliverdin. Here we investigated a therapeutic role for CO and CO-primed cells in acute pancreatitis (AP). In a mouse model of AP, treatment with CO-releasing molecule-2 (CORM-2) decreased mortality, pancreatic damage, and lung injury. CORM-2 decreased systemic inflammatory cytokines, suppressed systemic and pancreatic macrophage TNF-α secretion, and inhibited macrophage TLR4 receptor complex expression. In both human and mouse cells, CORM-2 inhibited endogenous and exogenous ligand-dependent TLR4 activation, which indicates that CORM-2 could be therapeutic for both early and late stages of AP, which involve sterile- and endotoxin-mediated inflammation, respectively. Mice engrafted with TLR4-deficient hematopoietic cells were protected against caerulein-induced AP. In the absence of leukocyte TLR4 expression, CORM-2 did not confer additional protection, which indicates that CORM-2-dependent effects are mediated via suppression of macrophage TLR4 activation. We determined that CO was directly responsible for the protective effects of CORM-2 in AP, as inactive forms of CORM-2 were ineffective. Importantly, adoptive transfer of CORM-2-primed cells reduced AP. Such a therapeutic approach would translate the beneficial effects of CO-based therapies, avoiding CO- or CO-RM-mediated toxicities in AP and a wide range of diseases.

Abstract 1552: Cigarette smoke induces TNF-α secretion from macrophages through a pathway consisting of PPARγ, MUC1, ERK and JNK.

Abstract The glycoprotein Mucin 1 (MUC1 in human and Muc1 in animals) is expressed in the lung and has been shown to be associated with lung carcinogenesis. Recently we have found that cigarette smoke (CS) significantly increased MUC1 expression in mouse lung macrophages and that MUC1 is required for CS-induced tumor necrosis factor-alpha (TNF-α) secretion from macrophages. Because CS potently elicits chronic pulmonary inflammation that is important for the development of lung cancer, we investigated the cell signaling pathways for CS-induced MUC1 expression and MUC1-mediated TNF-α secretion in macrophages using an in vitro model. The results showed that: CS extract (CSE) strongly induced MUC1 expression at both the mRNA and protein levels; Suppression of PPARγ effectively blocked CSE-induced MUC1 expression in THP1 cells, suggesting CSE induces MUC1 expression through PPARγ-mediated transcription; The induction of TNF-α expression was effectively blocked when ERK and JNK were blocked, suggesting these pathways are involved in CSE-induced TNF-α expression in macrophages; Knockdown of MUC1 significantly suppressed CSE-induced ERK and JNK activation; and Suppression of PPARγ that effectively blocked CSE-induced MUC1 expression also inhibited CSE-induced TNF-α secretion from macrophages. Thus, our results suggest a possible involvement of a signaling pathway consisting of PPARγ, MUC1 and ERK/JNK for CSE-induced TNF-α secretion from macrophages that may contribute to inflammation-associated lung cancer development. Note: This work is supported by the NIH/NIEHS grant 1R01ES017328. Citation Format: Xiuling Xu, Mabel T. Padilla, Alexandria Wells, Kwang Chul Kim, yong Lin. Cigarette smoke induces TNF-α secretion from macrophages through a pathway consisting of PPARγ, MUC1, ERK and JNK. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1552. doi:10.1158/1538-7445.AM2013-1552

Inulin stimulates phagocytosis of PMA‐treated THP‐1 macrophages by involvement of PI3‐kinases and MAP kinases

Inulin is a polysaccharide that enhances various immune responses, mainly to T and B cells, natural killer cells, and macrophages in vivo and in vitro. Previous reports describe that inulin activates macrophages indirectly by affecting the alternative complement pathway. In this study, we examined the direct effect of inulin on PMA-treated THP-1 macrophages. Inulin treatment did not stimulate the proliferation of THP-1 macrophages at all. However, inulin treatment significantly increased phagocytosis of the polystyrene beads without the influence of serum. Doses of around 1 mg/mL had the maximal effect, and significant progression of phagocytosis occurred at times treated over 6 h. Inulin augmented phagocytosis not only with polystyrene beads but also with apoptotic cancer cells. The inulin-induced phagocytosis uptake was suppressed in Toll-like receptor (TLR) 4 mutated C3H/HeJ mice peritoneal macrophages. Moreover, inulin-induced THP-1 macrophage TNF-α secretion was inhibited using a blocking antibody specific to TLR4, suggesting that TLR4 is involved in the binding of inulin to macrophages. Furthermore, we used specific kinase inhibitors to assess the involvement of inulin-induced phagocytosis and revealed that phosphoinositide 3-kinase and mitogen-activated protein kinase, especially p38, participated in phagocytosis. These results suggest that inulin affects macrophages directly by involving the TLR4 signaling pathway and stimulating phagocytosis for enhancing immunomodulation.

Immunostimulatory properties of glycated chitosan

Glycated chitosan (GC) is a new compound derived from chitosan by attaching galactose molecules to the chitosan molecules. GC was designed for immune stimulations in combination with phototherapies in the cancer treatment. The future clinical applications require a thorough understanding of the properties of GC. Murine macrophage cells (RAW264.7) were used to investigate NO formation and TNFα secretion stimulated by GC. Murine mammary tumor cells (EMT6) were treated in vitro and in vivo by laser irradiation with 980 nm in combination with GC stimulation. Here is the first in a series of studies designed to understand the immunological mechanisms of GC. Our in vitro results show that GC could enter into macrophages to stimulate NO generation and TNFα secretion. GC could further enhance the TNFα secretion of macrophages stimulated by laser treated tumor cells. Our in vivo results also show immunological effects of GC, particularly in inducing tumor-specific immune responses. Our results indicated that GC was a strong immunological stimulant for cancer treatment, particularly when combined with laser phototherapies.

The promotion of type 1 T helper cell responses to cationic polymers in vivo via toll-like receptor-4 mediated IL-12 secretion

Cationic polymers with nucleic acid drug delivery ability are widely used in experimental and clinical studies. However, their interactions with the immune systems are rarely studied. In the present study, cationic polymers including PEI, polylysine, cationic dextran and cationic gelatin exhibited strong stimulation on Th1 response which was characterized by the induction of the proliferation of CD4 + T cells and the secretion of Th1 related cytokines. Experiments performed on macrophages demonstrated that cationic polymers specifically stimulated the macrophage to secrete IL-12 which is one of the main Th1-inducing cytokines. The result that MyD88 inhibitor remarkably reduced the IL-12 expression induced by cationic polymers suggested that this stimulation was mainly mediated by toll-like receptor (TLR) pathway. Additionally, cationic polymers could strongly inhibit LPS-induced TNF-α secretion in macrophages. This result implied that cationic polymers may interact with macrophages through TLR-4 which is the receptor of LPS. The following test of inhibiting IL-12 expression stimulated by cationic polymers using TLR-4 antibody proved that the stimulation was mainly mediated by TLR-4. Data in the present study demonstrated that the stimulation ability of cationic polymer was related with its cationic degree and neutralizing cationic polymer with anionic polymer completely abrogated the stimulation effect. The molecular weight of the polymers also influenced their stimulation ability, larger molecular means stronger stimulation ability. In conclusion, the present study revealed that cationic polymers could promote Th1 responses in vivo via TLR-4 mediated IL-12 secretion and the molecular weight and cationic degree of the polymers determined the stimulation ability.