Inflammatory Macrophage Function Research Articles

Acute Hypoxia Following Disuse Atrophy in Aged Mice Enhances Cellular Remodeling and Whole-body Strength During Early Recovery

Age-related impairments in muscle recovery following disuse atrophy are associated with altered macrophage metabolism and blunted inflammatory function. HIF-1α is a key regulator of macrophage metabolism and inflammatory function. Therefore, we investigated the effects of acute hypoxia on muscle recovery following disuse in aging. We hypothesized that transient hypoxic exposure following disuse in aged mice would enhance macrophage metabolism and inflammatory status, resulting in improved muscle cellular remodeling and recovery. Accordingly, old (~20 months) and young adult male mice (~4 months) were exposed to acute (24 hours) normobaric hypoxia (8% O2) immediately following 14-days hindlimb unloading. We characterized muscle phenotype and function during early recovery (4- and 7-days) with and without hypoxia exposure. We found that acute hypoxia stimulated the expression of inflammatory (TNF-α, VEGF p<0.01) and glycolytic transcripts (PFK-1 p<0.05), LDH, PDH p=0.08) downstream of HIF-1α in aged skeletal muscle under basal conditions. Following disuse atrophy, transient hypoxic exposure enhanced macrophage inflammatory function, indicated by increased phagocytosis capacity (p<0.01), and promoted early skeletal muscle cellular remodeling events, including enhanced muscle satellite cell content (p<0.05). Furthermore, these effects facilitated the recovery of whole-body strength in aged mice indicated by a return to baseline values (p>0.05). The results of this investigation suggest that hypoxic exposure following disuse atrophy promoted inflammatory macrophage function, muscle cellular remodeling, and enhanced early recovery in aged mice. These findings elucidate the potential benefits of hypoxia in manipulating macrophage function to ameliorate age-related deficits in muscle recovery following disuse atrophy. This research was supported by R01AG076075 (MJD) and the National Institutes of Health Ruth L. Kirschstein National Research Service Award 5T32DK091317 from the National Institute of Diabetes and Digestive and Kidney Diseases. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Macrophage Polarization, Metabolic Reprogramming, and Inflammatory Effects in Ischemic Heart Disease.

Macrophages are highly plastic cells, and the polarization-activating actions that represent their functional focus are closely related to metabolic reprogramming. The metabolic reprogramming of macrophages manifests itself as a bias toward energy utilization, transforming their inflammatory phenotype by changing how they use energy. Metabolic reprogramming effects crosstalk with the biological processes of inflammatory action and are key to the inflammatory function of macrophages. In ischemic heart disease, phenotypic polarization and metabolic shifts in circulating recruitment and tissue-resident macrophages can influence the balance of inflammatory effects in the heart and determine disease regression and prognosis. In this review, we present the intrinsic link between macrophage polarization and metabolic reprogramming, discussing the factors that regulate macrophages in the inflammatory effects of ischemic heart disease. Our aim is to estabilsh reliable regulatory pathways that will allow us to better target the macrophage metabolic reprogramming process and improve the symptoms of ischemic heart disease.

HBeAg mediates inflammatory functions of macrophages by TLR2 contributing to hepatic fibrosis

BackgroundWe and others have confirmed activation of macrophages plays a critical role in liver injury and fibrogenesis during HBV infection. And we have also proved HBeAg can obviously induce the production of macrophage inflammatory cytokines compared with HBsAg and HBcAg. However, the receptor and functional domain of HBeAg in macrophage activation and its effects and mechanisms on hepatic fibrosis remain elusive.MethodsThe potentially direct binding receptors of HBeAg were screened and verified by Co-IP assay. Meanwhile, the function domain and accessible peptides of HBeAg for macrophage activation were analyzed by prediction of surface accessible peptide, construction, and synthesis of truncated fragments. Furthermore, effects and mechanisms of the activation of hepatic stellate cells induced by HBeAg-treated macrophages were investigated by Transwell, CCK-8, Gel contraction assay, Phospho Explorer antibody microarray, and Luminex assay. Finally, the effect of HBeAg in hepatic inflammation and fibrosis was evaluated in both human and murine tissues by immunohistochemistry, immunofluorescence, ELISA, and detection of liver enzymes.ResultsHerein, we verified TLR-2 was the direct binding receptor of HBeAg. Meanwhile, C-terminal peptide (122-143 aa.) of core domain in HBeAg was critical for macrophage activation. But arginine-rich domain of HBcAg hided this function, although HBcAg and HBeAg shared the same core domain. Furthermore, HBeAg promoted the proliferation, motility, and contraction of hepatic stellate cells (HSCs) in a macrophage-dependent manner, but not alone. PI3K-AKT-mTOR and p38 MAPK signaling pathway were responsible for motility phenotype of HSCs, while the Smad-dependent TGF-β signaling pathway for proliferation and contraction of them. Additionally, multiple chemokines and cytokines, such as CCL2, CCL5, CXCL10, and TNF-α, might be key mediators of HSC activation. Consistently, HBeAg induced transient inflammation response and promoted early fibrogenesis via TLR-2 in mice. Finally, clinical investigations suggested that the level of HBeAg is associated with inflammation and fibrosis degrees in patients infected with HBV.ConclusionsHBeAg activated macrophages via the TLR-2/NF-κB signal pathway and further exacerbated hepatic fibrosis by facilitating motility, proliferation, and contraction of HSCs with the help of macrophages.

804-P: Empagliflozin Reduces Inflammation and Bioenergetics in Proinflammatory Human Macrophages: Clues to Mechanisms of Blood Vessel Protection?

SGLT-2 inhibitors (SGLT2i) reduce cardiovascular (CV) risk in people with type 2 diabetes and atherosclerotic CV diseases. The inflammatory function of macrophages (Mφ) - which play a pivotal role in atherosclerosis - is strictly dependent on their metabolism. Aim: To determine whether empagliflozin (EMPA) reduces inflammation and modifies bioenergetic metabolism in proinflammatory human Mφ (M1). Methods: M1 were differentiated from healthy donors’ monocytes and incubated with/without EMPA 100 µM for 16h. Biomarkers of inflammation and oxidative stress were quantified by qPCR. Steady-state energetic metabolism (fluxes: pmol/min for 5x104 cells) was measured by indirect microcalorimetry [oxidations of lipids (LipOX,) glucose and amino acids; anaerobic glycolysis (AnaerGlyc); tricarboxylic acid cycle (TCA); energy expenditure (EPR); maximum estimate of ATP production (ATPflux)] which is based on the integration of measured O2 and H+ (Agilent Seahorse), lactate and NH4 (enzymatic method) fluxes with the stoichiometric equations of metabolic pathways. Results: In M1, EMPA reduces (≈50%) inflammation (IL1β, IL8, TNFα and MCP1; p<0.05-0.001) and oxidative stress (GPX and HO-1; p <0.05). EMPA lowers OCR (133±9.7 vs. 153±10.3, p<0.001), LipOX (1.15±0.1 vs. 1.33±0.1; p<0.005), TCA (45±3 vs. 52±4; p<0.001), AnaerGlyc (210±23 vs. 268±24; p<0.01), ATPflux (1097±94 vs. 1313±94; p<0.005) and EPR (83±7 vs. 98±7 µJ/min; p<0.001). After dissipating mitochondrial membrane potential and forcing maximal OCR with FCCP, TCA (77±11 vs. 97±12, p=0.001), LipOX (1.7±0.3 vs. 2.2±0.4, p<0.005) and EPR (125±17 vs. 153±17; p<0.005), but not AnaerGlyc, remain inhibited by EMPA. Conclusions: EMPA alters M1 inflammation along with cytosolic (AnaerGlyc) and - to a greater extent - mitochondrial (TCA) bioenergetics. EMPA-induced metabolic dysfunction of M1 in vivo might result into reduced metaflammation and contribute to SGLT2i-dependent CV protection. Disclosure V. Spigoni: None. G. Cinquegrani: None. F. Fantuzzi: None. S. Lorusso: None. A. Dei cas: Other Relationship; Self; Novo Nordisk. R. C. Bonadonna: Advisory Panel; Self; Sanofi, Speaker’s Bureau; Self; AstraZeneca, Boehringer Ingelheim Pharmaceuticals, Inc., Eli Lilly and Company. Funding Italian Diabete Ricerca Foundation; Eli Lilly Italy

Crosstalk Between LXR and Caveolin-1 Signaling Supports Cholesterol Efflux and Anti-InflammatoryPathwaysin Macrophages.

Macrophages are immune cells that play crucial roles in host defense against pathogens by triggering their exceptional phagocytic and inflammatory functions. Macrophages that reside in healthy tissues also accomplish important tasks to preserve organ homeostasis, including lipid uptake/efflux or apoptotic-cell clearance. Both homeostatic and inflammatory functions of macrophages require the precise stability of lipid-rich microdomains located at the cell membrane for the initiation of downstream signaling cascades. Caveolin-1 (Cav-1) is the main protein responsible for the biogenesis of caveolae and plays an important role in vascular inflammation and atherosclerosis. The Liver X receptors (LXRs) are key transcription factors for cholesterol efflux and inflammatory gene responses in macrophages. Although the role of Cav-1 in cellular cholesterol homeostasis and vascular inflammation has been reported, the connection between LXR transcriptional activity and Cav-1 expression and function in macrophages has not been investigated. Here, using gain and loss of function approaches, we demonstrate that LXR-dependent transcriptional pathways modulate Cav-1 expression and compartmentation within the membrane during macrophage activation. As a result, Cav-1 participates in LXR-dependent cholesterol efflux and the control of inflammatory responses. Together, our data show modulation of the LXR-Cav-1 axis could be exploited to control exacerbated inflammation and cholesterol overload in the macrophage during the pathogenesis of lipid and immune disorders, such as atherosclerosis.

Acute Hemolysis and Heme Suppress Anti-CD40 Antibody-Induced Necro-Inflammatory Liver Disease.

Clearance of red blood cells and hemoproteins is a key metabolic function of macrophages during hemolytic disorders and following tissue injury. Through this archetypical phagocytic function, heme is detoxified and iron is recycled to support erythropoiesis. Reciprocal interaction of heme metabolism and inflammatory macrophage functions may modify disease outcomes in a broad range of clinical conditions. We hypothesized that acute hemolysis and heme induce acute anti-inflammatory signals in liver macrophages. Using a macrophage-driven model of sterile liver inflammation, we showed that phenylhydrazine (PHZ)-mediated acute erythrophagocytosis blocked the anti-CD40 antibody-induced pathway of macrophage activation. This process attenuated the inflammatory cytokine release syndrome and necrotizing hepatitis induced by anti-CD40 antibody treatment of mice. We further established that administration of heme-albumin complexes specifically delivered heme to liver macrophages and replicated the anti-inflammatory effect of hemolysis. The anti-inflammatory heme-signal was induced in macrophages by an increased intracellular concentration of the porphyrin independently of iron. Overall, our work suggests that induction of heme-signaling strongly suppresses inflammatory macrophage function, providing protection against sterile liver inflammation.

β3-integrin Leu33Pro gain of function variant does not modulate inflammatory activity in human derived macrophages in diabetes.

Objective: We aimed to investigate the association between the Leu33Pro (rs5918) polymorphism in β3-integrin with diabetic complications and inflammatory function of macrophages depending on the genotype in subjects with diabetes mellitus.Material and methods: We determined the Leu33Pro polymorphism in 186 diabetic subjects and collected laboratory data. Monocytes from 24 patients were collected for macrophage differentiation to determine the inflammatory activity by treating with different stimulants.Results: We could demonstrate that human derived differentiated macrophages expressed β3‑integrin. Their secretory capacity upon inflammatory stimulation did not reveal any differences depending on the Leu33Pro variant. We found trends for an association of the polymorphism with the presence of diabetic nephropathy (p = 0.071), as well as with creatinine [1.32 mg/dL (1) vs. 0.98 mg/dL (0)] (p = 0.029 in recessive model) and glomerular filtration rate [75.6 ml/min ± 22 vs. 62.3 ml/min ± 25] (p = 0.076 in recessive model) as quantitative markers of kidney function.Conclusion: Despite the expression of β3‑integrin in human macrophages, the Leu33Pro polymorphism in β3‑integrin does not modify the inflammatory response upon stimulation but might play a role in the progression of diabetic nephropathy. Further studies are necessary to substantiate such a hypothesis.

Turning a pathogen protein into a therapeutic tool for sepsis.

Sepsis causes unacceptably high amounts of deaths worldwide. It is a huge unmet medical need, and new therapeutic interventions for sepsis and septic shock are urgently needed. By studying the mechanism by which a bacterial protein undermines the inflammatory function of macrophages, Kim et al, in the last issue of EMBO Molecular Medicine, have developed a new therapeutic protein drug, which appears to have very promising protective activities in a well-validated and aggressive polymicrobial sepsis model in mice. The chimeric protein is thought to limit macrophage inflammation while activating phagocytosis, and so, it hits two macrophage pathways at once.

Abstract 792: Core Cell Survival Requirements of Hypoxia Inducible Factors in Macrophages Dominate Isoform-Specific Function during Cardiac Repair

Objective: Hypoxia inducible factors (HIF) regulate the adaptive response to ischemic injury and enhancement of HIF levels has been proposed as a therapeutic target to improve tissue repair after acute myocardial infarction (MI). HIFs also regulate the inflammatory function of macrophages, the main protagonists of tissue repair after MI, but it is unknown whether changes in macrophage HIF levels will affect outcomes after MI. Using a murine model of acute MI and conditional knockouts, we investigated a role for macrophage HIFs in tissue repair after MI. Methods and Results: In mice subjected to permanent occlusion MI, we observed an accumulation of hypoxic cardiac macrophages and sequential stabilization of HIF-2α followed by HIF-1α, which persisted into the development of heart failure. In patients with ischemic cardiomyopathy, flow cytometry and single-cell transcriptomics revealed a parallel stabilization of HIFs and hypoxia signaling in cardiac macrophages. Since HIFs were stabilized early after MI in cardiac macrophages, we selectively targeted macrophage HIFs using conditional knockouts. Selective deletion of macrophage HIF-2α promoted cardiac macrophage production of IL-10, activating fibroblasts and stimulating collagen deposition, culminating in improved ventricular remodeling and preservation of systolic function. Similarly, selective deletion of macrophage HIF-1α improved cardiac repair; however, this was mechanistically distinct from HIF-2α, inhibiting HIF-1α-dependent proteolytic destruction of MerTK and leading to improved efferocytosis by cardiac macrophages. Contrary to our expectations, loss of both HIF-1α and HIF-2α in hypoxic macrophages enhanced mitochondrial reactive oxygen species and activated necroptosis, leading to increased cell death and cardiac rupture after acute MI. Inhibition of necroptosis with necrostatin-1 attenuated hypoxic macrophage cell death and significantly improved survival after acute MI. Conclusions: These data imply strategies that broadly enhance or inhibit HIFs will lead to catastrophic outcomes after MI, while selective inhibition of macrophage HIF-1α or HIF-2α may enhance tissue repair, preserve systolic function, and limit progression to heart failure.

Regulation of Inflammatory Functions of Macrophages and T Lymphocytes by NFAT5.

The transcription factor NFAT5, also known as TonEBP, belongs to the family of Rel homology domain-containing factors, which comprises the NF-κB proteins and the calcineurin-dependent NFAT1 to NFAT4. NFAT5 shares several structural and functional features with other Rel-family factors, for instance it recognizes DNA elements with the same core sequence as those bound by NFAT1 to 4, and like NF-κB it responds to Toll-like receptors (TLR) and activates macrophage responses to microbial products. On the other hand, NFAT5 is quite unique among Rel-family factors as it can be activated by hyperosmotic stress caused by elevated concentrations of extracellular sodium ions. NFAT5 regulates specific genes but also others that are inducible by NF-κB and NFAT1 to 4. The ability of NFAT5 to do so in response to hypertonicity, microbial products, and inflammatory stimuli may extend the capabilities of immune cells to mount effective anti-pathogen responses in diverse microenvironment and signaling conditions. Recent studies identifying osmostress-dependent and -independent functions of NFAT5 have broadened our understanding of how NFAT5 may modulate immune function. In this review we focus on the role of NFAT5 in macrophages and T cells in different contexts, discussing findings from in vivo mouse models of NFAT5 deficiency and reviewing current knowledge on its mechanisms of regulation. Finally, we propose several questions for future research.

Aluminum doped carbon nanodots as potent adjuvants on the mammalian macrophages

In this manuscript, we aimed to report the synthesis of aluminum (Al) incorporated carbon nanodots (CD) and their activities on the immune cells. A green synthesis method involving the in situ doping of the nanodot was conducted. Synthesized nanodots immunomodulatory and immunostimulatory activities were tested in vitro on the macrophages. The produced carbon dots were water-soluble, fluorescent and monodispersed, with an average diameter of around 10-20nm. After Al-doping, their surface properties, stability, crystallinity, as well as their fluorescent and optical properties were evaluated. These Al-CDs displayed no cytotoxicity and enhanced the pro-inflammatory activities of the mammalian macrophages with much lower aluminum concentrations (‰ 20) compared to that of conventional aluminum salt, by virtue of which they have the potential to serve as safe and effective adjuvant carrier. The stability of the nanocarriers was found to be persistent for over 3 months at room temperature with no significant formation of the aggregates. These results support the promise of such nanodots as the new generation non-toxic adjuvant candidates. Al incorporation changed the activity of carbon nanodot (CD). Plain CD did not have major affect on the inflammatory function of macrophages. Al incorporated CD was able to stimulate the macrophages in the absence of danger stimulus which supports its adjuvant potential. Compared to the Al salt as a control Al-CD was more potent even with ‰ 20 Al concentration on the inflammatory activity of the macropahges in vitro.

Polarization of Rheumatoid Macrophages by TNF Targeting Through an IL-10/STAT3 Mechanism.

Macrophages contribute to the pathogenesis of rheumatoid arthritis (RA). They can display different states of activation or “polarization,” notably the so-called inflammatory “M1” and the various alternative “M2” polarizations, characterized by distinct functions. Data regarding the effects of RA anti-cytokine biological disease-modifying anti-rheumatic drugs (bDMARDs) on macrophage polarization are scarce. We aimed to assess in vitro modulation of macrophage polarization by bDMARDs targeting pro-inflammatory cytokines in RA. We generated monocyte derived macrophages using blood samples from 20 RA patients with active RA and 30 healthy controls. We evaluated in vitro the impact on M1 inflammatory macrophages of: etanercept (ETA), adalimumab (ADA), certolizumab (CZP), tocilizumab (TCZ), and rituximab (RTX). We assessed the impact on macrophage polarization using flow cytometry and RTqPCR to study the expression of surface markers and perform functional studies of cytokine production, phagocytosis, and negative feedback control of inflammation. Among evaluated bDMARDs, anti-TNF agents modulated the polarization of inflammatory macrophages by decreasing inflammatory surface markers (CD40, CD80) and favoring alternative markers (CD16, CD163, MerTK). Anti-TNF agents also induced alternative functions in macrophages activated in inflammatory condition with (i) the inhibition of inflammatory cytokines (TNF, IL-6, IL-12), (ii) an increase in phagocytosis. These findings were mechanistically related to an increase in early IL-10 production, responsible for higher negative feedback control of inflammation involving SOCS3 and Gas6. This IL-10 effect was STAT3-dependent. Anti-TNF agents not only inhibit in vitro inflammatory functions of macrophages, but also favor resolution of inflammation through polarization toward alternative features specifically involving the IL-10/STAT3 axis.

Protein Disulfide Isomerase Silence Inhibits Inflammatory Functions of Macrophages by Suppressing Reactive Oxygen Species and NF-κB Pathway.

Macrophages play an essential role in inflammation. Protein disulfide isomerase (PDI) is central to the redox system, which is closely linked with the inflammatory function of macrophages. However, the relationship between PDI and inflammation is still unknown. In this study, we tested the effects of PDI on inflammatory responses in RAW 264.7 macrophages stimulated with lipopolysaccharide (LPS). Using CRISPR/Cas9 system, we found that PDI knockout suppressed migration, M1 polarization, and secretion of tumor necrosis factor-α (TNF-α) and interluekin-6 (IL-6). The repression of these inflammatory processes was accompanied by decreased production of reactive oxygen species (ROS). PDI ablation also inactivated the phosphorylation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) and activated the phosphorylation of NF-κB inhibitor alpha (IκBα). These findings demonstrate that PDI knockout inhibits the inflammatory function of macrophages by decreasing ROS production and inactivating NF-κB pathway.

Role of Bone Marrow Mononuclear Cell Seeding for Nanofiber Vascular Grafts.

Electrospinning is a promising technology that provides biodegradable nanofiber scaffolds for cardiovascular tissue engineering. However, success with these materials has been limited, and the optimal combination of scaffold parameters for a tissue-engineered vascular graft (TEVG) remains elusive. The purpose of the present study is to evaluate the effect of bone marrow mononuclear cell (BM-MNC) seeding in electrospun scaffolds to support the rational design of optimized TEVGs. Nanofiber scaffolds were fabricated from co-electrospinning a solution of polyglycolic acid and a solution of poly(ι-lactide-co-ɛ-caprolactone) and characterized with scanning electron microscopy. Platelet activation and cell seeding efficiency were assessed by ATP secretion and DNA assays, respectively. Cell-free and BM-MNC seeded scaffolds were implanted in C57BL/6 mice (n = 15/group) as infrarenal inferior vena cava (IVC) interposition conduits. Animals were followed with serial ultrasonography for 6 months, after which grafts were harvested for evaluation of patency and neotissue formation by histology and immunohistochemistry (n = 10/group) and PCR (n = 5/group) analyses. BM-MNC seeding of electrospun scaffolds prevented stenosis compared with unseeded scaffolds (seeded: 9/10 patent vs. unseeded: 1/10 patent, p = 0.0003). Seeded vascular grafts demonstrated concentric laminated smooth muscle cells, a confluent endothelial monolayer, and a collagen-rich extracellular matrix. Platelet-derived ATP, a marker of platelet activation, was significantly reduced after incubating thrombin-activated platelets in the presence of seeded scaffolds compared with unseeded scaffolds (p < 0.0001). In addition, reduced macrophage infiltration and a higher M2 macrophage percentage were observed in seeded grafts. The beneficial effects of BM-MNC seeding apply to electrospun TEVG scaffolds by attenuating stenosis through the regulation of platelet activation and inflammatory macrophage function, leading to well-organized neotissue formation. BM-MNC seeding is a valuable technique that can be used in the rational design of optimal TEVG scaffolds.

An interaction between Scribble and the NADPH oxidase complex controls M1 macrophage polarization and function

The polarity protein Scribble (SCRIB) regulates apical-basal polarity, directional migration and tumour suppression in Drosophila and mammals. Here we report that SCRIB is an important regulator of myeloid cell functions including bacterial infection and inflammation. SCRIB interacts directly with the NADPH oxidase (NOX) complex in a PSD95/Dlg/ZO-1 (PDZ)-domain-dependent manner and is required for NOX-induced reactive oxygen species (ROS) generation in culture and invivo. On bacterial infection, SCRIB localized to phagosomes in a leucine-rich repeat-dependent manner and promoted ROS production within phagosomes to kill bacteria. Unexpectedly, SCRIB loss promoted M1 macrophage polarization and inflammation. Thus, SCRIB uncouples ROS-dependent bacterial killing activity from M1 polarization and inflammatory functions of macrophages. Modulating the SCRIB-NOX pathway can therefore identify ways to manage infection and inflammation with implications for chronic inflammatory diseases, sepsis and cancer.

The omega-3 fatty acid docosahexaenoic acid favorably modulates the inflammatory pathways and macrophage polarization within aorta of LDLR(-/-) mice.

The omega-3 fatty acid docosahexaenoic acid (DHA) has potent anti-atherogenic properties but its mechanisms of action at the vascular level remain poorly explored. Knowing the broad range of molecular targets of omega-3 fatty acids, microarray analysis was used to open-mindedly evaluate the effects of DHA on aorta gene expression in LDLR(-/-) mice and better understand its local anti-atherogenic action. Mice were fed an atherogenic diet and received daily oral gavages with oils rich in oleic acid or DHA. Bioinformatics analysis of microarray data first identified inflammation and innate immunity as processes the most affected by DHA supplementation within aorta. More precisely, several down-regulated genes were associated with the inflammatory functions of macrophages (e.g., CCL5 and CCR7), cell movement (e.g., ICAM-2, SELP, and PECAM-1), and the major histocompatibility complex (e.g., HLA-DQA1 and HLA-DRB1). Interestingly, several genes were identified as specific biomarkers of macrophage polarization, and their changes suggested a preferential orientation toward a M2 reparative phenotype. This observation was supported by the upstream regulator analysis highlighting the involvement of three main regulators of macrophage polarization, namely PPARγ (z-score=2.367, p=1.50×10(-13)), INFγ (z-score=-2.797, p=2.81×10(-14)), and NFκB (z-score=2.360, p=6.32×10(-9)). Moreover, immunohistological analysis of aortic root revealed an increased abundance of Arg1 (+111%, p=0.01), a specific biomarker of M2 macrophage. The present study showed for the first time that DHA supplementation during atherogenesis is associated with protective modulation of inflammation and innate immunity pathways within aorta putatively through the orientation of plaque macrophages toward a M2 reparative phenotype.

A Circadian Clock Gene, Rev-erbα, Modulates the Inflammatory Function of Macrophages through the Negative Regulation of Ccl2 Expression

Disruption of the circadian rhythm is a contributory factor to clinical and pathophysiological conditions, including cancer, the metabolic syndrome, and inflammation. Chronic and systemic inflammation are a potential trigger of type 2 diabetes and cardiovascular disease and are caused by the infiltration of large numbers of inflammatory macrophages into tissue. Although recent studies identified the circadian clock gene Rev-erbα, a member of the orphan nuclear receptors, as a key mediator between clockwork and inflammation, the molecular mechanism remains unknown. In this study, we demonstrate that Rev-erbα modulates the inflammatory function of macrophages through the direct regulation of Ccl2 expression. Clinical conditions associated with chronic and systemic inflammation, such as aging or obesity, dampened Rev-erbα gene expression in peritoneal macrophages from C57BL/6J mice. Rev-erbα agonists or overexpression of Rev-erbα in the murine macrophage cell line RAW264 suppressed the induction of Ccl2 following an LPS endotoxin challenge. We discovered that Rev-erbα represses Ccl2 expression directly through a Rev-erbα-binding motif in the Ccl2 promoter region. Rev-erbα also suppressed CCL2-activated signals, ERK and p38, which was recovered by the addition of exogenous CCL2. Further, Rev-erbα impaired cell adhesion and migration, which are inflammatory responses activated through the ERK- and p38-signaling pathways, respectively. Peritoneal macrophages from mice lacking Rev-erbα display increases in Ccl2 expression. These data suggest that Rev-erbα regulates the inflammatory infiltration of macrophages through the suppression of Ccl2 expression. Therefore, Rev-erbα may be a key link between aging- or obesity-associated impairment of clockwork and inflammation.

Lesional Accumulation of CD163-Expressing Cells in the Gut of Patients with Inflammatory Bowel Disease

Monocytes/macrophages displaying different markers of activation/differentiation infiltrate the inflamed gut of patients with inflammatory bowel diseases (IBD), but the role that each monocyte/macrophage subpopulation plays in the pathogenesis of IBD is not fully understood. The hemoglobin scavenger receptor CD163, a specific marker of monocytes/macrophages, has been associated with either anti-inflammatory or inflammatory functions of macrophages in several pathologies. In this study we examined the tissue distribution and function of CD163-expressing monocytes/macrophages in IBD. CD163 RNA and protein expression was more pronounced in IBD in comparison to normal controls, with no significant difference between Crohn's disease and Ulcerative colitis. In IBD, over-expression of CD163 was restricted to areas with active inflammation and not influenced by current therapy. Immunohistochemical analysis confirmed the accumulation of CD163-expressing cells in IBD, mostly around and inside blood vessels, thus suggesting that these cells are partly recruited from the systemic circulation. Indeed, FACS analysis of circulating mononuclear cells showed that the fractions of CD163-positive monocytes were increased in IBD patients as compared to controls. Functionally, interleukin-6 up-regulated CD163 expression in lamina propria mononuclear cells and mucosal explants of normal subjects. In IBD blood and mucosal cell cultures, cross-linking of CD163 with a specific monoclonal anti-CD163 antibody enhanced tumor necrosis factor-α synthesis. These findings indicate that IBD mucosa is abundantly infiltrated with CD163-positive cells, which could contribute to amplify the inflammatory cytokine response.

Intravenous immunoglobulin treatment on anti-GM1 antibodies associated neuropathies inhibits cholera toxin and galectin-1 binding to ganglioside GM1

Intravenous immunoglobulin (IVIg) therapy is efficacious in some peripheral nervous autoimmune diseases associated with anti-GM1 antibodies. Numerous mechanisms of action have been proposed to account for the immunomodulatory effects of IVIg in immune-mediated diseases. Up to now, the mechanisms of action of IVIg in pathology associated with anti-GM1 antibodies have not been well documented. In the present study, we discovered that IVIg did not inhibit the binding of anti-GM1 antibodies to its antigen and IVIg perfusions did not reduce anti-GM1 antibodies titers. In this observation, we have the result different from the hypothesis of presence of anti-idiotypic antibodies in different IVIg preparations, and show that IVIg inhibits the binding of cholera toxin and galectin-1 to GM1-expressing cells using flow cytometry. Our results suggest that the correct ratio galactosyl/agalactosyl IgG in IVIg interact with macrophages receptors to down-regulate inflammatory function of macrophages and autoimmune diseases in peripheral nerve system.

Invasive fungal infection in an elderly patient with defective inflammatory macrophage function

Macrophages are known to be involved in pathogen recognition and mediate host immune responses, but, in the clinical setting, their purported central role in opportunistic fungal infections has not been demonstrated to date. Herein, we describe a patient with invasive testicular aspergillosis in whom we found, for the first time, a defect in macrophage function.