Monocyte Inflammatory Responses Research Articles

Characterization of platelet signature on monocytes isolated from HIV infected individuals

Abstract Background Higher levels of platelet-monocyte complexes (PMCs) are detected in human immunodeficiency virus (HIV)-infected individuals. Such complexes are implicated in expansion of monocytes exhibiting inflammatory phenotype, and their translocation into tissues, thus promoting development of cerebrovascular and cardiovascular disorders. Here we have recruited small sub-set of HIV-infected individuals to investigate how platelets cause epigenetic changes in monocytes of HIV-infected individuals. We posit that the formation of PMCs facilitates monocyte differentiation via exchange of biomaterial between activated platelets and monocytes during HIV-infection. Methods We performed ATAC-seq to measure changes in chromatin accessibility from two types of monocytes, PMC-derived or non-PMC-derived, isolated from HIV-infected persons. Results Using ATAC-Seq data, we were able to detect distinct changes in chromatin accessibility patterns within the genomic regions of proinflammatory mediators in PMC-derived monocytes. Chromatin accessibility of inflammatory genes was dramatically increased in PMC-derived monocytes. This suggested to us a possibility of active exchange of molecules that causes such alterations in monocytes. Conclusions Increases in chromatin accessibility of pro-inflammatory genes occur in the PMC-derived monocytes in persons with HIV. This change is likely due to the transfer of platelet antigens to monocytes via cell-cell interaction, suggesting a novel mechanism through which platelets trigger inflammatory response in monocytes. Thus, our initial findings pave a way that has a strong diagnostic as well as therapeutic value.

Autologous intraoperative cell salvage ameliorates suppression of transfusion-related monocyte and dendritic cell inflammatory responses

Abstract ABO compatible allogeneic blood transfusion (ABT) is associated with transfusion-related immune modulation (TRIM) and poor patient outcomes including perioperative infection and myocardial infarction. Intraoperative cell salvage (ICS) enables collection, processing and reinfusion of autologous blood lost during surgery. We investigated whether immune suppression associated with ABT could be reduced by using ICS. Suitable orthopaedic patients were consented and recruited to the study (n=20, HREC/17/QRBW/685). 10mL anticoagulated blood (EDTA) was collected from the patient (pre-operatively) and from the ICS blood product. An established whole blood culture model was used to assess changes to monocyte and myeloid dendritic cell (mDC) inflammatory responses (intracellular cytokine staining for IL-6, IL-8, IL-10, IL-12, IL-1α, TNF-α, MIP-1α, MIP-1β, MCP-1, IP-10) following exposure of the patient’s pre-operative blood to ABO compatible allogenic blood (Blood Service, Kelvin Grove) or their ICS blood (P<0.05 ANOVA). Exposure to ABT significantly suppressed the inflammatory response of both mDC (IL-10, IL-12, IL-1α, IL-8, TNF-a, MIP-α, MIP-1β) and monocytes (IL-10, IL-6, IL-12, IL-1α, IL-8, IL-10, IL-12, TNF-α and MIP-1α). Compared to ABT, exposure to the patients’ own (ICS) blood improved mDC IL-8, IL-10, IL-12, TNF-α and MIP-1α production and monocyte IL-10 and MIP-1β production. We provide in vitro evidence that ICS may reduce ABT associated adverse outcomes associated with improved inflammatory response and immune competence post-transfusion.

Hippocampal damage and seizure severity during acute viral encephalitis are determined by the intensity of the infiltrating inflammatory monocyte response

Abstract The immunological response to CNS viral infection must balance the need for effective viral clearance with the need to preserve irreplaceable neurons. Failure to achieve this balance may result in death or severe cognitive impairment. We have observed hippocampal injury, compromised cognitive function, and seizures in C57BL/6 mice following acute infection with TMEV. We established that an initial innate immune response controlled by inflammatory monocyte infiltration into the brain is responsible for this neural injury. To better understand the pathogenic mechanisms involved in monocyte recruitment to the CNS we asked whether reducing the initial viral inoculum impacted the evolution of neural injury. We found that mice infected with standard (2×105 PFU) or low inoculum (1.25×104 PFU) TMEV exhibited a graded inflammatory response. Notably, a 16-fold reduction in viral inoculum resulted in 80% attenuation of the inflammatory monocyte response, concomitant with a 90% attenuation in acute production of CCL2 and complete abrogation of acute increases in TNFα and IL-6 in the hippocampus. Cognitive performance was preserved in low inoculum mice and seizure burden was highly attenuated. Despite the introduction of 16-times less virus, viral load in the brain was equivalent at 3 dpi between groups, indicating that the amount of replicating virus was not associated with reduced neuropathology. Our findings support a model in which the earliest host response to pathogen in the CNS shapes the size of the inflammatory response and constrains the downstream pathological sequelae.

Transition Metal Containing Particulate Matter Promotes Th1 and Th17 Inflammatory Response by Monocyte Activation in Organic and Inorganic Compounds Dependent Manner.

In recent years, a significant increase in the frequency of disorders caused by air pollutants has been observed. Here we asked whether transition metal-containing particulate matter (TMCPM), a component of air pollution, has an effect on the activity of human CD4+ T cell subsets (Th1, Th2, Th17, and Treg). Peripheral blood mononuclear cells (PBMC) from healthy donors were cultured with or without NIST (SRM 1648a—standard urban particulate matter purchased from the National Institute for Standards and Technology) and LAP (SRM 1648a particulate matter treated within 120 min with cold oxygen plasma) preparations of TMCPM, differing in organic compounds content. Data show that TMCPM treatment increased the level of CD4+ cells positive for IFN-γ and IL-17A, specific for Th1 and Th17 cells, respectively. Moreover, a substantial decrease in frequency of Foxp3 positive CD4+ cells was observed in parallel. This effect was more pronounced for NIST particles, containing more organic components, including endotoxin (LPS - lipopolysaccharide) and required the presence of monocytes. Inactivation of LPS by treatment of TMCPM with polymyxin B reduced the inflammatory response of monocytes and Th subsets but did not abolish this activity, suggesting a role of their inorganic components. In conclusion, treatment of human PBMC with TMCPM skews the balance of Th1/Th2 and Treg/Th17 cells, promoting polarization of CD4+ T cells into Th1 and Th17 subsets. This phenomenon requires activation of monocytes and depends on the organic and inorganic fractions, including endotoxin content in TMCPM, as significantly higher inflammatory response was observed for the NIST comparing to LAP. This observation may shed a new light on the role of TMCPM in development and exacerbation of allergies, inflammatory, and autoimmune disorders.

25-vitamin D reduces inflammation in uremic environment

Chronic kidney disease (CKD) is characterized by loss of renal function and a consequent increase of serum uremic toxins, which contribute to inflammation status. Deficiency of 25-vitamin D, often found in patients with CKD, has been included as an inflammatory factor since it might modulate the immune system. The aim of this study was to investigate the role of 25-vitamin D on inflammatory pathways in healthy and uremic environment. Toll-like receptor 4 (TLR4), oxidative stress (ROS), vitamin D receptor (VDR), 1-α hydroxylase (CYP27), 24 hydroxylase, cathelicidin, and MCP-1 were evaluated in monocytes exposed to a uremic serum pool compared with healthy pool. The human monocytes lineage (U937) was incubated with or without 25-vitamin D (50 ng/ml for 24 hours). TRL4, VDR, CYP27, CYP24, and ROS were evaluated by flow cytometry. We used ELISA to measure IL-6, TNF-α, IL-10, cathelicidin, and MCP-1 in the cell culture supernatant. We observed a higher expression of TRL-4, IL-6, TNF-α, IL-10, cathelicidin and MCP-1 in monocytes incubated with uremic serum when compared with serum from healthy individuals. Supplementation of 25-vitamin D was able to reduce the expression of TRL4, cathelicidin, and MCP-1 in the uremic environment. There was no difference in the expression of VDR, CYP27 and CYP24 intracellular enzymes. This in vitro study showed that the uremic pool activates inflammatory response in monocytes, which was reversed by 25-vitamin D supplementation; this finding suggests that 25-vitamin D has an anti-inflammatory role in the uremic environment.

The RNA binding protein Quaking represses host interferon response by downregulating MAVS

ABSTRACTQuaking (QKI) is an RNA-binding protein (RBP) involved in multiple aspects of RNA metabolism and many biological processes. Despite a known immune function in regulating monocyte differentiation and inflammatory responses, the degree to which QKI regulates the host interferon (IFN) response remains poorly characterized. Here we show that QKI ablation enhances poly(I:C) and viral infection-induced IFNβ transcription. Characterization of IFN-related signalling cascades reveals that QKI knockout results in higher levels of IRF3 phosphorylation. Interestingly, complementation with QKI-5 isoform alone is sufficient to rescue this phenotype and reduce IRF3 phosphorylation. Further analysis shows that MAVS, but not RIG-I or MDA5, is robustly upregulated in the absence of QKI, suggesting that QKI downregulates MAVS and thus represses the host IFN response. As expected, MAVS depletion reduces IFNβ activation and knockout of MAVS in the QKI knockout cells completely abolishes IFNβ induction. Consistently, ectopic expression of RIG-I activates stronger IFNβ induction via MAVS-IRF3 pathway in the absence of QKI. Collectively, these findings demonstrate a novel role for QKI in negatively regulating host IFN response by reducing MAVS levels.

Expression of AXL receptor tyrosine kinase relates to monocyte dysfunction and severity of cirrhosis.

Infectious complications in patients with cirrhosis frequently initiate episodes of decompensation and substantially contribute to the high mortality. Mechanisms of the underlying immuneparesis remain underexplored. TAM receptors (TYRO3/AXL/MERTK) are important inhibitors of innate immune responses. To understand the pathophysiology of immuneparesis in cirrhosis, we detailed TAM receptor expression in relation to monocyte function and disease severity prior to the onset of acute decompensation. TNF-α/IL-6 responses to lipopolysaccharide were attenuated in monocytes from patients with cirrhosis (n = 96) compared with controls (n = 27) and decreased in parallel with disease severity. Concurrently, an AXL-expressing (AXL+) monocyte population expanded. AXL+ cells (CD14+CD16highHLA-DRhigh) were characterised by attenuated TNF-α/IL-6 responses and T cell activation but enhanced efferocytosis and preserved phagocytosis of Escherichia coli Their expansion correlated with disease severity, complications, infection, and 1-yr mortality. AXL+ monocytes were generated in response to microbial products and efferocytosis in vitro. AXL kinase inhibition and down-regulation reversed attenuated monocyte inflammatory responses in cirrhosis ex vivo. AXL may thus serve as prognostic marker and deserves evaluation as immunotherapeutic target in cirrhosis.

E-cigarette flavored pods induce inflammation, epithelial barrier dysfunction, and DNA damage in lung epithelial cells and monocytes

E-cigarette flavored pods are increasing in use among young adults. Although marketed as a safer alternative to conventional cigarettes, the health effects of e-cigarette flavored pods are unknown. We hypothesized that e-cigarette flavored pods would cause oxidative stress, barrier dysfunction, and an inflammatory response in monocytes and lung epithelial cells. JUUL pod flavors (Fruit Medley, Virginia Tobacco, Cool Mint, Crème Brulee, Cool Cucumber, Mango, and Classic Menthol) and similar pod flavors (Just Mango-Strawberry Coconut and Caffé Latte) were tested. These pod flavors generated significant amounts of acellular ROS and induced significant mitochondrial superoxide production in bronchial epithelial cells (16-HBE). Lung epithelial cells (16-HBE, BEAS-2B) and monocytes (U937) exposed to various pod aerosols resulted in increased inflammatory mediators, such as IL-8 or PGE2. JUUL pod flavors, Crème Brulee and Cool Cucumber, caused epithelial barrier dysfunction in 16-HBE cells. Moreover, tested flavors also showed DNA damage upon exposure in monocytes. We determined the chemical constituents present in various flavors. Our data suggest that these constituents in flavored pods induce oxidative stress, inflammation, epithelial barrier dysfunction, and DNA damage in lung cells. These data provide insights into the regulation of e-cigarette flavored pods, as well as constituents in these flavors.

Potent reduction of plasma lipoprotein (a) with an antisense oligonucleotide in human subjects does not affect ex vivo fibrinolysis

It is postulated that lipoprotein (a) [Lp(a)] inhibits fibrinolysis, but this hypothesis has not been tested in humans due to the lack of specific Lp(a) lowering agents. Patients with elevated Lp(a) were randomized to antisense oligonucleotide [IONIS-APO(a)Rx] directed to apo(a) (n = 7) or placebo (n = 10). Ex vivo plasma lysis times and antigen concentrations of plasminogen, factor XI, plasminogen activator inhibitor 1, thrombin activatable fibrinolysis inhibitor, and fibrinogen at baseline, day 85/92/99 (peak drug effect), and day 190 (3 months off drug) were measured. The mean ± SD baseline Lp(a) levels were 477.3 ± 55.9 nmol/l in IONIS-APO(a)Rx and 362.1 ± 89.9 nmol/l in placebo. The mean± SD percentage change in Lp(a) for IONIS-APO(a)Rx was -69.3 ± 12.2% versus -5.4 ± 6.9% placebo (P < 0.0010) at day 85/92/99 and -15.6 ± 8.9% versus 3.2 ± 12.2% (P = 0.003) at day 190. Clot lysis times and coagulation/fibrinolysis-related biomarkers showed no significant differences between IONIS-APO(a)Rx and placebo at all time points. Clot lysis times were not affected by exogenously added Lp(a) at concentrations up to 200 nmol/l to plasma with very low (12.5 nmol/l) Lp(a) levels, whereas recombinant apo(a) had a potent antifibrinolytic effect. In conclusion, potent reductions of Lp(a) in patients with highly elevated Lp(a) levels do not affect ex vivo measures of fibrinolysis; the relevance of any putative antifibrinolytic effects of Lp(a) in vivo needs further study.

Pseudomonas aeruginosa PA5oct Jumbo Phage Impacts Planktonic and Biofilm Population and Reduces Its Host Virulence.

The emergence of phage-resistant mutants is a key aspect of lytic phages-bacteria interaction and the main driver for the co-evolution between both organisms. Here, we analyze the impact of PA5oct jumbo phage treatment on planktonic/cell line associated and sessile P. aeruginosa population. Besides its broad-spectrum activity and efficient bacteria reduction in both airway surface liquid (ASL) model, and biofilm matrix degradation, PA5oct appears to persist in most of phage-resistant clones. Indeed, a high percentage of resistance (20/30 clones) to PA5oct is accompanied by the presence of phage DNA within bacterial culture. Moreover, the maintenance of this phage in the bacterial population correlates with reduced P. aeruginosa virulence, coupled with a sensitization to innate immune mechanisms, and a significantly reduced growth rate. We observed rather unusual consequences of PA5oct infection causing an increased inflammatory response of monocytes to P. aeruginosa. This phenomenon, combined with the loss or modification of the phage receptor, makes most of the phage-resistant clones significantly less pathogenic in in vivo model. These findings provide new insights into the general knowledge of giant phages biology and the impact of their application in phage therapy.

GROWTH DIFFERENTIATION FACTOR 15 IS CORRELATED TO MARKERS OF IMMUNOSENESCENCE IN MONOCYTES

Immunosenescence is an age-associated decrease in function of immune cells precipitated by a variety of mechanisms and affecting nearly every immune cell subset. In myeloid cell subsets, aging reduces numbers of phagocytes and impairs their functional abilities, including antigen presentation, phagocytosis, and bacterial clearance. Recently, we have described an aging effect on several functions indicating immunosenescence in monocytes, including impaired mitochondrial function and reduced inflammatory cytokine gene expression during stimulation with lipopolysaccharide (LPS). We hypothesized that circulating factors altered by the aging process underly these changes. Growth/differentiation factor-15 (GDF-15) is a distant member of the transforming growth factor-beta superfamily that has known anti-inflammatory effects in macrophages and has recently been shown to be highly differentially expressed during aging. We used biobanked serum and plasma samples to assay circulating GDF-15 levels in subjects from our previous studies and examined correlations between GDF-15 levels and monocyte mitochondrial function and inflammatory responses. Monocyte interleukin-6 production due to LPS stimulation was negatively correlated to plasma GDF-15 levels (p = 0.046). Additionally, serum GDF-15 was positively correlated to circulating CD16+ monocyte proportions (p = 0.021) and negatively correlated to monocyte mitochondrial respiratory capacity (p < 0.001). Therefore, our data suggest that GDF-15 is a potential circulating factor affecting a variety of monocyte functions and promoting monocyte immunosenescence, and thus is an attractive candidate for therapeutic intervention to ameliorate this.

Salt increases monocyte CCR2 expression and inflammatory responses in humans.

Inflammation may play a role in the link between high salt intake and its deleterious consequences. However, it is unknown whether salt can induce proinflammatory priming of monocytes and macrophages in humans. We investigated the effects of salt on monocytes and macrophages in vitro and in vivo by performing a randomized crossover trial in which 11 healthy human subjects adhered to a 2-week low-salt and high-salt diet. We demonstrate that salt increases monocyte expression of CCR2, a chemokine receptor that mediates monocyte infiltration in inflammatory diseases. In line with this, we show a salt-induced increase of plasma MCP-1, transendothelial migration of monocytes, and skin macrophage density after high-salt diet. Macrophages demonstrate signs of an increased proinflammatory phenotype after salt exposure, as represented by boosted LPS-induced cytokine secretion of IL-6, TNF, and IL-10 in vitro, and by increased HLA-DR expression and decreased CD206 expression on skin macrophages after high-salt diet. Taken together, our data open up the possibility for inflammatory monocyte and macrophage responses as potential contributors to the deleterious effects of high salt intake.

T cell-derived soluble glycoprotein GPIbα mediates PGE2 production in human monocytes activated with the vaccine adjuvant MDP.

Vaccine adjuvants containing analogs of microbial products activate pattern recognition receptors (PRRs) on antigen-presenting cells, including monocytes and macrophages, which can cause prostaglandin E2 (PGE2) release and consequently undesired inflammatory responses and fever in vaccine recipients. Here, we studied the mechanism of PGE2 production by human monocytes activated with muramyl dipeptide (MDP) adjuvant, which activates cytosolic nucleotide-binding oligomerization domain 2 (NOD2). In rabbits, administration of MDP elicited an early increase in PGE2 followed by fever. In human monocytes, MDP alone did not induce PGE2 production. However, high amounts of PGE2 and the proinflammatory cytokines IL-1β and IL-6 were secreted by monocytes activated with MDP in the presence of conditioned medium obtained from CD3 bead-isolated T cells (Tc CM) but not from those isolated without CD3 beads. Mass spectrometry and immunoblotting revealed that the costimulatory factor in Tc CM was glycoprotein Ib α (GPIbα). Antibody-mediated blockade of GPIbα or of its receptor, Mac-1 integrin, inhibited the secretion of PGE2, IL-1β, and IL-6 in MDP + Tc CM-activated monocytes, whereas recombinant GPIbα protein increased PGE2 production by MDP-treated monocytes. In vivo, COX2 mRNA abundance was reduced in the liver and spleen of Mac-1 KO mice after administration of MDP compared with that of treated wild-type mice. Our findings suggest that the production of PGE2 and proinflammatory cytokines by MDP-activated monocytes is mediated by cooperation between two signaling pathways: one delivered by MDP through NOD2 and a second through activation of Mac-1 by T cell-derived GPIbα.

The Estrogen-Induced miR-19 Downregulates Secretory Leucoprotease Inhibitor Expression in Monocytes

Compared to females, males are more susceptible to acute viral and other respiratory tract infections that display greater severity and higher mortality. In contrast, females tend to fare worse with chronic inflammatory diseases. Circulating 17β-estradiol (E2) is a female-specific factor that may influence the progression of human lung diseases. Here we hypothesize that E2 modulates the inflammatory response of monocytes through microRNA (miRNA)-based modulation of secretory leucoprotease inhibitor (SLPI), an antiprotease with immunomodulatory effects. Monocytic cells were treated ± E2, and differentially expressed miRNAs were identified using PCR profiling. Cells were transfected with miRNA mimics or antimiRs and SLPI mRNA and protein levels were quantified. Luciferase activity assay using wildtype and ΔmiR-19a/b-SLPI3′UTR reporter constructs and chromatin immunoprecipitation on E2-treated monocytes were performed. E2 downregulated SLPI and upregulated miR-19 expression in monocytes. Transfection with premiR-19b reduced SLPI mRNA and protein levels and this effect was abrogated using antimiRs against miR-19b. miR-19b directly binds the SLPI 3′UTR. The mechanism responsible for E2-mediated upregulation of miR-19 occurs via increased MIR17HG promoter activity mediated by c-MYC. Overall E2 decreases SLPI expression in human monocytic cells, via changes in miRNA expression and highlights the potential for estrogen to modulate the innate immune system.

Effects of EPA and DHA Supplementation on Plasma Specialized Pro-resolving Lipid Mediators and Blood Monocyte Inflammatory Response in Subjects with Chronic Inflammation (OR29-01-19)

ObjectivesThe role of n-3 fatty acid-derived specialized pro-resolving mediators (SPMs), including the novel docosapentaenoic acid (DPA) products, in reducing inflammation in humans has not been determined. We evaluated the differential effects of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) supplementation on plasma SPMs and the resulting impact on the inflammatory response of peripheral blood monocytes. MethodsIn a randomized, controlled, crossover trial, 21 subjects (9 men and 12 women, 50–75 y) with chronic inflammation (C-reactive protein > 2 μg/mL) entered a 4-week lead-in control phase (high oleic sunflower oil, 3 g/d) and then two sequential 10-week supplementation phases with pure EPA or DHA (3 g/d each), separated by a 10-week washout phase. Plasma phospholipid (PL) fatty acid composition and SPMs, including their precursors, were measured at the end of each phase. Following lipopolysaccharides (LPS) stimulation, the inflammatory response of blood monocytes was assessed by inflammatory gene expression. ResultsEPA increased PL EPA (P < 0.001) and plasma concentrations of 18-HEPE, the precursor of the E-series resolvins (RvEs) (P < 0.001). The increase in plasma 18-HEPE concentrations, was associated with the increase in PL EPA (β = 14.9 pg/ml, P < 0.01). However, RvEs were undetectable. EPA increased PL DPA (P < 0.001) but not DPA-derived SPMs. DHA increased PL DHA and plasma concentrations of 17-HDHA and 14-HDHA, the precursors of DHA-derived SPMs (P < 0.001). DHA also significantly increased PL EPA and 18-HEPE (P < 0.001), suggesting some DHA retroconversion to EPA. Interestingly, DHA lowered PL DPA (P < 0.001) but increased the DPA-derived SPMs RvD5n-3 DPA and MaR1n-3 DPA (P < 0.001). In monocytes, while both EPA and DHA lowered the LPS-induced expression of TNFA(P < 0.03 and P < 0.001, respectively), TNFA expression was inversely correlated with plasma concentrations of MaR1n-3 DPA (ρ = –0.32, P < 0.04). ConclusionsRelative to EPA, DHA supplementation increases a broader range of SPMs, with EPA and DHA differentially affecting PL DPA and DPA-derived SPMs. Plasma concentrations of MaR1n-3 DPA following EPA and DHA supplementation are associated with an attenuated inflammatory response in blood monocytes, suggesting a potential role of this SPM in reducing inflammation in humans. Funding SourcesFunded by USDA/NIFA and Cohn Student Award. Supporting Tables, Images and/or Graphs▪

Docosahexaenoic Acid and Eicosapentaenoic Acid Supplementation Differentially Modulate Pro- and Anti-inflammatory Cytokines in Subjects with Chronic Inflammation (OR29-02-19)

ObjectivesDespite extensive works on the cardioprotective effects of fish oil containing docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), the distinct mechanisms by which DHA and EPA modulate inflammation and plasma lipids are not well characterized. We compared the effects of DHA and EPA supplementation on serum cytokines and blood monocyte inflammatory response and on blood lipids in subjects with chronic inflammation. MethodsTwenty-one subjects (9 men and 12 women, 50–75 y) with chronic inflammation (CRP > 2 μg/mL) were enrolled in a randomized, controlled crossover trial consisting of a 4-week lead-in control phase (high oleic sunflower oil, 3 g/d) followed by two sequential 10-week supplementation phases with pure DHA or EPA (3 g/d each) with a 10-week washout in between. Serum concentrations of cytokines were determined by electrochemiluminescence (ECL) assay. Following lipopolysaccharides (LPS) stimulation of blood monocytes, gene expression and secretion of cytokines were assessed by qPCR and ECL. Plasma lipid concentrations were measured by enzymatic assays. ResultsRelative to the control phase, DHA reduced the LPS-induced gene expression of pro-inflammatory TNFA (median % change: –45%, P < 0.001), IL6 (–51%, P < 0.05), MCP1 (–28%, P < 0.04) as well as anti-inflammatory IL10 (–33%, P < 0.02) and the secretion of TNF-α (–41%, P < 0.02), MCP-1 (–29%, P < 0.01), and IL-10 (–47%, P < 0.05) in monocytes. On the other hand, EPA increased serum concentrations of IL-10 (+14%, P < 0.05) and lowered only TNFAexpression (–20%, P < 0.03) in monocytes. When compared to EPA supplementation, DHA decreased serum concentrations of MCP-1 (P < 0.03), and monocyte MCP-1 secretion (P < 0.05) and IL10 expression (P < 0.04). Regarding plasma concentrations of lipids, relative to the control phase, both DHA (–16%, P < 0.001) and EPA decreased triglycerides (–22%, P < 0.001) while only DHA increased LDL-cholesterol (+7%, P < 0.02). ConclusionsDHA and EPA differently modulate the balance between pro- and anti-inflammatory cytokines in serum and blood monocytes in subjects with chronic inflammation. While DHA inhibits a broad range of pro- and anti-inflammatory cytokines, EPA has a relatively minor role in lowering pro-inflammatory cytokines but preserves the anti-inflammatory IL-10. DHA, but not EPA, increases LDL-cholesterol. Funding SourcesFunded by USDA/NIFA.

Resveratrol attenuates the pathogenic and inflammatory properties of Porphyromonas gingivalis

Porphyromonas gingivalis has been strongly associated with chronic periodontitis, which affects tooth-supporting tissues. This Gram-negative anaerobic bacterium produces a repertoire of virulence factors that modulate tissue destruction directly or indirectly by the induction of inflammatory processes. The aim of this study was to investigate the effects of resveratrol, a major polyphenol found in grapes and wine, on the growth and virulence properties of P.gingivalis as well as on gingival keratinocyte tight junction integrity and the host inflammatory response. Resveratrol exhibited antibacterial activity that may result from damage to the bacterial cell membrane. Resveratrol also killed a pre-formed P.gingivalis biofilm and reduced bacterial adherence to matrix proteins. In addition, resveratrol had a protective effect on the integrity of the keratinocyte tight junctions by inhibiting its breakdown by P.gingivalis. This may be related to the ability of resveratrol to inhibit the protease activities of P.gingivalis. Lastly, resveratrol reduced P.gingivalis-mediated activation of the NF-κB signaling pathway and attenuated TREM-1 gene expression as well as soluble TREM-1 secretion in monocytes. The effect on NF-κB activation likely results from the ability of resveratrol to act as a PPAR-γ agonist. In summary, the antibacterial, anti-adherence, and antiprotease properties of resveratrol, as well as its ability to protect the gingival keratinocyte barrier and attenuate the inflammatory response in monocytes suggest that it may be a promising novel therapeutic agent for treating periodontal disease.

Hepatitis B Virus-Induced Imbalance of Inflammatory and Antiviral Signaling by Differential Phosphorylation of STAT1 in Human Monocytes.

It is not clear how hepatitis B virus (HBV) modulates host immunity during chronic infection. In addition to the key mediators of inflammatory response in viral infection, monocytes also express a high-level IFN-stimulated gene, CH25H, upon response to IFN-α exerting an antiviral effect. In this study, the mechanism by which HBV manipulates IFN signaling in human monocytes was investigated. We observed that monocytes from chronic hepatitis B patients express lower levels of IFN signaling/stimulated genes and higher levels of inflammatory cytokines compared with healthy donors. HBV induces monocyte production of inflammatory cytokines via TLR2/MyD88/NF-κB signaling and STAT1-Ser727 phosphorylation and inhibits IFN-α-induced stat1, stat2, and ch25h expression through the inhibition of STAT1-Tyr701 phosphorylation and in an IL-10-dependent, partially autocrine manner. Further, we found that enhancement of STAT1 activity with a small molecule (2-NP) rescued HBV-mediated inhibition of IFN signaling and counteracted the induction of inflammatory cytokines. In conclusion, HBV contributes to the monocyte inflammatory response but inhibits their IFN-α/β responsiveness to impair antiviral innate immunity. These effects are mediated via differential phosphorylation of Tyr701 and Ser727 of STAT1.

Platelet-derived β2M regulates monocyte inflammatory responses.

β-2 Microglobulin (β2M) is a molecular chaperone for the major histocompatibility class I (MHC I) complex, hemochromatosis factor protein (HFE), and the neonatal Fc receptor (FcRn), but β2M may also have less understood chaperone-independent functions. Elevated plasma β2M has a direct role in neurocognitive decline and is a risk factor for adverse cardiovascular events. β2M mRNA is present in platelets at very high levels, and β2M is part of the activated platelet releasate. In addition to their more well-studied thrombotic functions, platelets are important immune regulatory cells that release inflammatory molecules and contribute to leukocyte trafficking, activation, and differentiation. We have now found that platelet-derived β2M is a mediator of monocyte proinflammatory differentiation through noncanonical TGFβ receptor signaling. Circulating monocytes from mice lacking β2M only in platelets (Plt-β2M-/-) had a more proreparative monocyte phenotype, in part dependent on increased platelet-derived TGFβ signaling in the absence of β2M. Using a mouse myocardial infarction (MI) model, Plt-β2M-/- mice had limited post-MI proinflammatory monocyte responses and, instead, demonstrated early proreparative monocyte differentiation, profibrotic myofibroblast responses, and a rapid decline in heart function compared with WT mice. These data demonstrate a potentially novel chaperone-independent, monocyte phenotype-regulatory function for platelet β2M and that platelet-derived 2M and TGFβ have opposing roles in monocyte differentiation that may be important in tissue injury responses.

Inflammatory monocyte response due to altered wall shear stress in an isolated femoral artery model.

Arteriogenesis (collateral formation) is accompanied by a pro-inflammatory state that may be related to the wall shear stress (WSS) within the neo-collateral vessels. Examining the pro-inflammatory component in situ or in vivo is complex. In an ex vivo mouse femoral artery perfusion model, we examined the effect of wall shear stress on pro-arteriogenic inflammatory markers and monocyte adhesion. In a femoral artery model with defined pulsatile flow, WSS was controlled (at physiological stress, 1.4×, and 2× physiological stress) during a 24 h perfusion before gene expression levels and monocyte adhesion were assessed. Significant upregulation of expression was found for the cytokine TNFα, adhesion molecule ICAM-1, growth factor TGFβ, and the transcription factor Egr-1 at varying levels of increased WSS compared to physiological control. Further, trends toward upregulation were found for FGF-2, the cytokine MCP-1 and adhesion molecules VCAM-1 and P-selectin with increased WSS. Finally, monocytes adhesion increased in response to increased WSS. We have developed a murine femoral artery model for studying changes in WSS ex vivo and show that the artery responds by upregulating inflammatory cytokines, adhesion molecules and growth factors consistent with previous in vivo findings.